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Non-small cell lung cancer (NSCLC) is the main histological subtype of lung cancer. For locally advanced and advanced NSCLC, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-targeted therapy has been the first choice for NSCLC patients with EGFR mutations. TKIs, as targeted drugs, inhibit kinase activity and autophosphorylation by competitively binding to the ATP binding site of the EGFR tyrosine kinase domain, which blocks the signal transduction mediated by EGFR and thus inhibits the proliferation of tumor cells. However, drug resistance to TKIs is inevitable. EGFR is also a highly glycosylated receptor tyrosine kinase, and a wide range of crosstalk occurs between phosphorylation and glycosylation. Therefore, can the phosphorylation state be altered by glycosylation to improve drug resistance? In this review, we summarize phosphorylation, glycosylation and the crosstalk between these processes as well as the current research status and methods. We also summarize the autophosphorylation and glycosylation sites of the EGFR protein and their crosstalk. By exploring the relationship between EGFR glycosylation and autophosphorylation in targeted TKI therapy, we find that research on EGFR glycosylation is crucial for targeted NSCLC treatment and will become a research direction for identifying potential targets related to regulating TKI drug sensitivity. [ABSTRACT FROM AUTHOR]

Lung adenocarcinoma (LUAD) is one of the deadliest cancers. Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-targeted therapy is an important approach for treating LUAD. However, the development of acquired resistance poses a serious clinical challenge. Our objective was to explore the differentially expressed genes (DEGs) associated with EGFR and detect biomarkers for diagnosing and treating osimertinib resistance in LUAD patients. LUAD datasets were downloaded from public databases. Differential expression analysis was performed to screen DEGs, and prognostic modules were constructed by Cox regression. Enrichment analysis, gene regulatory network analysis and immune microenvironment analysis were employed to explore the underlying mechanisms in LUAD. Finally, the expression of prognosis module genes (PMGs) was validated in 8 LUAD tissue specimens and 5 cell lines by qRT-PCR. In total, 13 differential module genes (BIRC3, CCT6A, CPLX2, GLCCI1, GSTA1, HLA-DQB2, ID1, KCTD12, MUC15, NOTUM, NT5E, TCIM, and TM4SF4) were screened for the construction of a prognostic module. Notably, CCT6A and KCTD12 demonstrated excellent accuracy in the diagnosis of LUAD. Immune dysregulation and BIRC3, HLA-DQB2, KCTD12, and NT5E expression were significantly associated with invasive immune cells in LUAD patients. The expression level of CCT6A was highest in PC9-OR and H1975-OR cells, while the expression level of KCTD12 was highest in paracancerous tissue and HBE cells. The constructed prognostic model showed promise in predicting the survival of LUAD patients. Notably, KCTD12 and CCT6A might be candidate biomarkers for improving diagnostic performance and guiding individualized therapy for EGFR-TKI-resistant LUAD patients. [ABSTRACT FROM AUTHOR]

Non-small cell lung cancer (NSCLC) is the main histological subtype of lung cancer. For locally advanced and advanced NSCLC, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-targeted therapy has been the first choice for NSCLC patients with EGFR mutations. TKIs, as targeted drugs, inhibit kinase activity and autophosphorylation by competitively binding to the ATP binding site of the EGFR tyrosine kinase domain, which blocks the signal transduction mediated by EGFR and thus inhibits the proliferation of tumor cells. However, drug resistance to TKIs is inevitable. EGFR is also a highly glycosylated receptor tyrosine kinase, and a wide range of crosstalk occurs between phosphorylation and glycosylation. Therefore, can the phosphorylation state be altered by glycosylation to improve drug resistance? In this review, we summarize phosphorylation, glycosylation and the crosstalk between these processes as well as the current research status and methods. We also summarize the autophosphorylation and glycosylation sites of the EGFR protein and their crosstalk. By exploring the relationship between EGFR glycosylation and autophosphorylation in targeted TKI therapy, we find that research on EGFR glycosylation is crucial for targeted NSCLC treatment and will become a research direction for identifying potential targets related to regulating TKI drug sensitivity.

Abstract Background Lung adenocarcinoma (LUAD) patients have a dismal survival rate because of cancer metastasis and drug resistance. The study aims to identify the genes that concurrently modulate EMT, metastasis and EGFR-TKI resistance, and to investigate the underlying regulatory mechanisms. Methods Cox regression and Kaplan–Meier analyses were applied to identify prognostic oncogenes in LUAD. Gene set enrichment analysis (GSEA) was used to indicate the biological functions of the gene. Wound-healing and Transwell assays were used to detect migratory and invasive ability. EGFR-TKI sensitivity was evaluated by assessing the proliferation, clonogenic survival and metastatic capability of cancer cells with treatment with gefitinib. Methylated RNA immunoprecipitation (MeRIP) and RNA immunoprecipitation (RIP) analyses established the level of m6A modification present on the target gene and the protein’s capability to interact with RNA, respectively. Single-sample gene set enrichment (ssGSEA) algorithm used to investigate levels of immune cell infiltration. Results Our study identified dual-specificity phosphatase 5 (DUSP5) as a novel and powerful predictor of adverse outcomes for LUAD by using public datasets. Functional enrichment analysis found that DUSP5 was positively enriched in EMT and transforming growth factor-beta (TGF-β) signaling pathway, a prevailing pathway involved in the induction of EMT. As expected, DUSP5 knockdown suppressed EMT via inhibiting the canonical TGF-β/Smad signaling pathway in in vitro experiments. Consistently, knockdown of DUSP5 was first found to inhibit migratory ability and invasiveness of LUAD cells in in vitro and prevent lung metastasis in in vivo. DUSP5 knockdown re-sensitized gefitinib-resistant LUAD cells to gefitinib, accompanying reversion of EMT progress. In LUAD tissue samples, we found 14 cytosine-phosphate-guanine (CpG) sites of DUSP5 that were negatively associated with DUSP5 gene expression. Importantly, 5′Azacytidine (AZA), an FDA-approved DNA methyltransferase inhibitor, restored DUSP5 expression. Moreover, RIP experiments confirmed that YTH N6-methyladenosine RNA binding protein 1 (YTHDF1), a m6A reader protein, could bind DUSP5 mRNA. YTHDF1 promoted DUSP5 expression and the malignant phenotype of LUAD cells. In addition, the DUSP5-derived genomic model revealed the two clusters with distinguishable immune features and tumor mutational burden (TMB). Conclusions Briefly, our study discovered DUSP5 which was regulated by epigenetic modification, might be a potential therapeutic target, especially in LUAD patients with acquired EGFR-TKI resistance. Graphical Abstract

Background: Effective treatment after EGFR-TKI resistance is of great clinical concern. We aimed to investigate the efficacy and safety of anlotinib in combination with an anti-PD-1/PD-L1 antibody in later-line therapy for EGFR-mutant NSCLC patients after TKI treatment failure and to explore the independent predictive factors of therapeutic efficacy. Methods: A total of 71 patients with confirmed advanced EGFR-mutated NSCLC who progressed after previous standard EGFR-TKI therapy but still failed after multiline treatments were included retrospectively in this study. Most of the patients had previously received at least three lines of treatment. All were treated with anlotinib combined with anti-PD-1 or anti-PD-L1 therapy. The safety of this combined treatment was assessed by the incidence of adverse events. The efficacy of the regimens was evaluated by survival analysis (OS, PFS, ORR, DCR). Results: The median follow-up period was 28.6 months (range: 2.3–54.0 months), and the median number of treatment lines was 4. The overall response rate (ORR) and disease control rate (DCR) were 19.7% and 77.5%, respectively. The median PFS was 5.8 months (95% CI 4.2–7.4 months), and the median OS was 17.1 months (95% CI 12.0–22.3 months). Patients who received immune checkpoint inhibitors plus anlotinib had an encouraging intracranial ORR of 38.5% and a DCR of 80.8%. ECOG performance status < 2 at baseline was independent protective factors of PFS. Metastatic organs and ECOG performance status were independent parameters in predicting OS. Treatment-related adverse events occurred in 66 (93.0%) patients; most of the adverse events were Grade 1–2, and no increase in adverse events was observed compared to monotherapy. Conclusion: Anlotinib combined with an anti-PD-1/PD-L1-based regimen exhibited promising efficacy and tolerance in NSCLC patients with EGFR mutations after previous TKI failure. The efficacy of this combined regimen in patients with EGFR mutations should be further evaluated. [ABSTRACT FROM AUTHOR]

Background: Lung adenocarcinoma (LUAD) patients have a dismal survival rate because of cancer metastasis and drug resistance. The study aims to identify the genes that concurrently modulate EMT, metastasis and EGFR-TKI resistance, and to investigate the underlying regulatory mechanisms. Methods: Cox regression and Kaplan–Meier analyses were applied to identify prognostic oncogenes in LUAD. Gene set enrichment analysis (GSEA) was used to indicate the biological functions of the gene. Wound-healing and Transwell assays were used to detect migratory and invasive ability. EGFR-TKI sensitivity was evaluated by assessing the proliferation, clonogenic survival and metastatic capability of cancer cells with treatment with gefitinib. Methylated RNA immunoprecipitation (MeRIP) and RNA immunoprecipitation (RIP) analyses established the level of m6A modification present on the target gene and the protein's capability to interact with RNA, respectively. Single-sample gene set enrichment (ssGSEA) algorithm used to investigate levels of immune cell infiltration. Results: Our study identified dual-specificity phosphatase 5 (DUSP5) as a novel and powerful predictor of adverse outcomes for LUAD by using public datasets. Functional enrichment analysis found that DUSP5 was positively enriched in EMT and transforming growth factor-beta (TGF-β) signaling pathway, a prevailing pathway involved in the induction of EMT. As expected, DUSP5 knockdown suppressed EMT via inhibiting the canonical TGF-β/Smad signaling pathway in in vitro experiments. Consistently, knockdown of DUSP5 was first found to inhibit migratory ability and invasiveness of LUAD cells in in vitro and prevent lung metastasis in in vivo. DUSP5 knockdown re-sensitized gefitinib-resistant LUAD cells to gefitinib, accompanying reversion of EMT progress. In LUAD tissue samples, we found 14 cytosine-phosphate-guanine (CpG) sites of DUSP5 that were negatively associated with DUSP5 gene expression. Importantly, 5′Azacytidine (AZA), an FDA-approved DNA methyltransferase inhibitor, restored DUSP5 expression. Moreover, RIP experiments confirmed that YTH N6-methyladenosine RNA binding protein 1 (YTHDF1), a m6A reader protein, could bind DUSP5 mRNA. YTHDF1 promoted DUSP5 expression and the malignant phenotype of LUAD cells. In addition, the DUSP5-derived genomic model revealed the two clusters with distinguishable immune features and tumor mutational burden (TMB). Conclusions: Briefly, our study discovered DUSP5 which was regulated by epigenetic modification, might be a potential therapeutic target, especially in LUAD patients with acquired EGFR-TKI resistance. [ABSTRACT FROM AUTHOR]

We investigated mRNA-lncRNA co-expression patterns in a cellular model system of non-small cell lung cancer (NSCLC) sensitive and resistant to the epithelial growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) erlotinib/gefitinib. The aim of this study was to unveil insights into the complex mechanisms of NSCLC targeted therapy resistance and epithelial-to-mesenchymal transition (EMT). Genome-wide RNA expression was quantified for weighted gene co-expression network analysis (WGCNA) to correlate the expression levels of mRNAs and lncRNAs. Functional enrichment analysis and identification of lncRNAs were conducted on modules associated with the EGFR-TKI response and/or intermediate EMT phenotypes. We constructed lncRNA-mRNA co-expression networks and identified key modules and their enriched biological functions. Processes enriched in the selected modules included RHO (A, B, C) GTPase and regulatory signaling pathways, apoptosis, inflammatory and interleukin signaling pathways, cell adhesion, cell migration, cell and extracellular matrix organization, metabolism, and lipid metabolism. Interestingly, several lncRNAs, already shown to be dysregulated in cancer, are connected to a small number of mRNAs, and several lncRNAs are interlinked with each other in the co-expression network. [ABSTRACT FROM AUTHOR]

Non-small cell lung cancer (NSCLC) is the most common lung cancer subtype. Although chemotherapy and targeted therapy are used for the treatment of patients with NSCLC, the survival rate remains very low. Recent findings suggested that aurora kinase A (AKA), a cell cycle regulator, is a potential target for NSCLC therapy. Previously, we reported that a chemical entity of quinazolin-4(3H)-one represents a new template for AKA inhibitors, with antiproliferative activity against cancer cells. A quinazolin-4(3H)-one derivative was further designed and synthesized in order to improve the pharmacokinetic properties and antiproliferation activity against NSCLC cell lines. The derivative, BIQO-19 (Ethyl 6-(4-oxo-3-(pyrimidin-2-ylmethyl)-3,4-dihydroquinazolin-6-yl)imidazo [1,2-a]pyridine-2-carboxylate), exhibited improved solubility and antiproliferative activity in NSCLC cells, including epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-resistant NSCLC cells. BIQO-19 effectively inhibited the growth of the EGFR-TKI-resistant H1975 NSCLC cells, with the suppression of activated AKA (p-AKA) expression in these cells. The inhibition of AKA by BIQO-19 significantly induced G2/M phase arrest and subsequently evoked apoptosis in H1975 cells. In addition, the combination of gefitinib and BIQO-19 exhibited synergistic antiproliferative activity in NSCLC cells. These findings suggest the potential of BIQO-19 as a novel therapeutic agent for restoring the sensitivity of gefitinib in EGFR-TKI-resistant NSCLC cells.

Introduction: According to current International Association for the Study of Lung Cancer guideline, physicians may first use plasma cell-free DNA (cfDNA) methods to identify epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-resistant mechanisms (liquid rebiopsy) for lung cancer. Tissue rebiopsy is recommended if the plasma result is negative. However, this approach has not been evaluated prospectively using next-generation sequencing (NGS). Methods: We prospectively enrolled patients with lung cancer with first-line EGFR-TKI resistance who underwent tissue rebiopsy. The rebiopsied tissues and cfDNA were sequenced using targeted NGS, ACTDrug®+, and ACTMonitor®Lung simultaneously. The clinicopathological characteristics and treatment outcomes were analyzed. Results: Totally, 86 patients were enrolled. Twenty-six (30%) underwent tissue biopsy but the specimens were inadequate for NGS. Among the 60 patients with paired tissue and liquid rebiopsies, two-thirds (40/60) may still be targetable T790M mutations were found in 29, including 14 (48%) only from tissue and 5 (17%) only from cfDNA. Twenty-four of them were treated with osimertinib, and progression-free survival was longer in patients without detectable T790M in cfDNA than in patients with detectable T790M in cfDNA (p=0.02). For the 31 T790M-negative patients, there were six with mesenchymal–epithelial transition factor (MET) amplifications, four with ERBB2 amplifications, and one with CCDC6-RET fusion. One with MET amplification and one with ERBB2 amplification responded to subsequent MET and ERBB2 targeting agents respectively. Conclusions: NGS after EGFR-TKI resistance may detect targetable drivers besides T790M. To do either liquid or tissue NGS only could miss patients with T790M. To do tissue and liquid NGS in parallel after EGFR-TKI resistance may find more patients with targetable cancers. [ABSTRACT FROM AUTHOR]

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) positively affect the initial control of non-small cell lung cancer (NSCLC). Rapidly acquired resistance to EGFR-TKIs is a major hurdle in successful treatment. However, the mechanisms that control the resistance of EGFR-TKIs remain largely unknown. RNA structures have widespread and crucial functions in many biological regulations; however, the functions of RNA structures in regulating cancer drug resistance remain unclear. Here, the psoralen analysis of RNA interactions and structures (PARIS) method is used to establish the higher-order RNA structure maps of EGFR-TKIs-resistant and -sensitive cells of NSCLC. Our results show that RNA structural regions are enriched in untranslated regions (UTRs) and correlate with translation efficiency (TE). Moreover, yrdC N6-threonylcarbamoyltransferase domain containing (YRDC) promotes resistance to EGFR-TKIs. RNA structure formation in YRDC 3′ UTR suppresses embryonic lethal abnormal vision-like 1 (ELAVL1) binding, leading to EGFR-TKI sensitivity by impairing YRDC translation. A potential therapeutic strategy for cancer treatment is provided using antisense oligonucleotide (ASO) to perturb the interaction between RNA and protein. Our study reveals an unprecedented mechanism through which the RNA structure switch modulates EGFR-TKI resistance by controlling YRDC mRNA translation in an ELAVL1-dependent manner.

Abstract Introduction Dysregulated ARID1A expression is frequently detected in lung adenocarcinoma (LUAD) and mediates significant changes in cancer behaviors and a poor prognosis. ARID1A deficiency in LUAD enhances proliferation and metastasis, which could be induced by activation of the Akt signaling pathway. However, no further exploration of the mechanisms has been performed. Methods Lentivirus was used for the establishment of the ARID1A knockdown (ARID1A-KD) cell line. MTS and migration/invasion assays were used to examine changes in cell behaviors. RNA-seq and proteomics methods were applied. ARID1A expression in tissue samples was determined by IHC. R software was used to construct a nomogram. Results ARID1A KD significantly promoted the cell cycle and accelerated cell division. In addition, ARID1A KD increased the phosphorylation level of a series of oncogenic proteins, such as EGFR, ErbB2 and RAF1, activated the corresponding pathways and resulted in disease progression. In addition, the bypass activation of the ErbB pathway, the activation of the VEGF pathway and the expression level changes in epithelial–mesenchymal transformation biomarkers induced by ARID1A KD contributed to the insensitivity to EGFR-TKIs. The relationship between ARID1A and the sensitivity to EGFR-TKIs was also determined using tissue samples from LUAD patients. Conclusion Loss of ARID1A expression influences the cell cycle, accelerates cell division, and promotes metastasis. EGFR-mutant LUAD patients with low ARID1A expression had poor overall survival. In addition, low ARID1A expression was associated with a poor prognosis in EGFR-mutant LUAD patients who received first-generation EGFR-TKI treatment. Video abstract

Objective: Epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI) is a first-line treatment for lung adenocarcinoma with EGFR-sensitive mutations, but acquired resistance to EGFR-TKIs remains a problem in clinical practice. The development of epithelial–mesenchymal transition (EMT) is a critical mechanism that induces acquired resistance to TKIs. Reversing acquired resistance to EGFR-TKIs through targeting the key molecules driving EMT provides an alternative choice for patients. We, therefore, aimed to explore the role of doublecortin-like kinase 1 (DCLK1) as an EMT driver gene in the acquired resistance of lung adenocarcinoma to EGFR-TKIs. Methods: The IC50 of Gefitinib or Osimertinib in PC9/HCC827 cells was measured using a cell counting kit-8 (CCK8) assay. The expression levels of EMT-related genes in PC9 and HCC827 cells were detected using RT-PCR and Western blot. Cell migration and invasion abilities were assessed via a transwell assay. For the in vivo experiments, PC9 cells were subcutaneously injected into BALB/c nude mice to form tumors. Upon harvesting, tumor tissues were retained for RT-PCR, Western blot, and polychromatic fluorescence staining to detect biomarker changes in the EMT process. Results: Gefitinib-resistant PC9 (PC9/GR) and Osimertinib-resistant HCC827 (HCC827/OR) cells showed remarkable activation of EMT and enhanced migration and invasion abilities compared to TKI-sensitive cells. In addition, DCLK1 expression was markedly increased in EGFR-TKI-resistant lung adenocarcinoma cells. The targeted knockout of DCLK1 effectively reversed the EMT phenotype in TKI-resistant cells and improved EGFR-TKI sensitivity, which was further validated by the in vivo experiments. Conclusions: DCLK1 facilitates acquired resistance to EGFR-TKI in lung adenocarcinoma by inducting EMT and accelerating the migration and invasion abilities of TKI-resistant cells. [ABSTRACT FROM AUTHOR]

Introduction: Dysregulated ARID1A expression is frequently detected in lung adenocarcinoma (LUAD) and mediates significant changes in cancer behaviors and a poor prognosis. ARID1A deficiency in LUAD enhances proliferation and metastasis, which could be induced by activation of the Akt signaling pathway. However, no further exploration of the mechanisms has been performed. Methods: Lentivirus was used for the establishment of the ARID1A knockdown (ARID1A-KD) cell line. MTS and migration/invasion assays were used to examine changes in cell behaviors. RNA-seq and proteomics methods were applied. ARID1A expression in tissue samples was determined by IHC. R software was used to construct a nomogram. Results: ARID1A KD significantly promoted the cell cycle and accelerated cell division. In addition, ARID1A KD increased the phosphorylation level of a series of oncogenic proteins, such as EGFR, ErbB2 and RAF1, activated the corresponding pathways and resulted in disease progression. In addition, the bypass activation of the ErbB pathway, the activation of the VEGF pathway and the expression level changes in epithelial–mesenchymal transformation biomarkers induced by ARID1A KD contributed to the insensitivity to EGFR-TKIs. The relationship between ARID1A and the sensitivity to EGFR-TKIs was also determined using tissue samples from LUAD patients. Conclusion: Loss of ARID1A expression influences the cell cycle, accelerates cell division, and promotes metastasis. EGFR-mutant LUAD patients with low ARID1A expression had poor overall survival. In addition, low ARID1A expression was associated with a poor prognosis in EGFR-mutant LUAD patients who received first-generation EGFR-TKI treatment. 7Ri7oJWPiw-vggUB99u973 Video abstract [ABSTRACT FROM AUTHOR]

Background: The therapeutic value of targeted therapies in patients with lung cancer is reduced when tumours acquire secondary resistance after an initial period of successful treatment. However, the molecular events behind the resistance to targeted therapies in lung cancer remain largely unknown. Aims: To discover the important role and mechanism of lncRNA BC in promoting tumor metastasis and influencing clinical prognosis of LUAD. Materials & Methods: Microarrays were used to screen a comprehensive set of lncRNAs with differential expression profiles in lung cancer cells. The functional role and mechanism of lncRNA were further investigated by gain‐ and loss‐of‐function assays. RNA pull‐down, protein assays, and mass spectrometry were used to identify proteins that interacted with lncRNA. TaqMan PCR was used to measure lncRNA in lung adenocarcinoma and adjacent nontumor tissues from 428 patients. The clinical significance of lncRNA identified was statistically confirmed in this cohort of patients. Results: In this study, we show that the long non‐coding RNA BC009639 (BC) is involved in acquired resistance to EGFR‐targeted therapies. Among the 235 long non‐coding RNAs that were differentially expressed in lung cancer cell lines, with different metastatic potentials, BC promoted growth, invasion, metastasis, and resistance to EGFR‐tyrosine kinase inhibitors (EGFR‐TKIs), both in vitro and in vivo. BC was highly expressed in 428 patients with lung adenocarcinoma (LUAD) and high BC expression correlated with reduced efficacy of EGFR‐TKI therapy. To uncover the molecular mechanism of BC‐mediated EGFR‐TKI resistance in lung cancer, we screened and identified nucleolin and hnRNPK that interact with BC. BC formed the splicing complex with nucleolin and hnRNPK to facilitate the production of a non‐protein‐coding inositol monophosphatase domain containing 1 (IMPAD1) splice variant, instead of the protein‐coding variant. The BC‐mediated alternative splicing (AS) of IMPAD1 resulted in the induction of the epithelial–mesenchymal transition and resistance to EGFR‐TKI in lung cancer. High BC expression correlated with clinical progress and poor survival among 402 patients with LUAD. Disscussion: Through alternative splicing, BC boosted the non‐coding IMPAD1‐203 transcript variant while suppressing the IMPAD1‐201 variant. In order to control the processing of pre‐mRNA, BC not only attracted RNA binding proteins (NCL, IGF2BP1) or splicing factors (hnRNPK), but also controlled the formation of the splicing‐regulator complex by creating RNA‐RNA‐duplexes. Conclusion: Our results reveal an important role for BC in mediating resistance to EGFR‐targeted therapy in LUAD through IMPAD1 AS and in implication for the targeted therapy resistance. [ABSTRACT FROM AUTHOR]

Ferroptosis has been characterised by disruption of the cell membrane through iron-related lipid peroxidation. However, regulation of iron homeostasis in lung cancer cells that are resistant to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) remains unclear. Transcriptome analysis identified a significant downregulation of apoptosis-associated tyrosine kinase (AATK) mRNA expression in gefitinib-resistant PC9 (PC9-GR) cells, which were found to be more susceptible to ferroptosis inducers. An in-depth analysis of publicly available datasets revealed that downregulation of AATK mRNA was associated with lymph node metastasis and poor prognosis in patients with lung adenocarcinoma. Knockdown of AATK-sensitised PC9, HCC827, and H441 cells to the ferroptosis inducer RSL3, whereas ectopic expression of AATK reduced RSL3-induced cell death in PC9-GR and HCC827-GR cells. Compared to PC9 cells, PC9-GR cells exhibited higher transferrin uptake, endosome recycling rate, and increased intracellular iron levels. Blocking iron transport reduced RSL3-induced ferroptosis in PC9-GR cells. Mechanistic studies showed that AATK localised to both early and recycling endosomes. Knockdown of AATK facilitated endosome recycling and elevated intracellular ferrous iron (Fe 2+ ) levels in PC9 cells. Conversely, ectopic expression of AATK delayed endosome recycling and reduced intracellular Fe 2+ levels in PC9-GR cells. Inhibition of AATK downregulation-induced iron accumulation decreased RSL3-induced ferroptosis. Taken together, our study indicates that the downregulation of AATK contributes to endosome recycling and iron accumulation, leading to an increased susceptibility to ferroptosis in EGFR-TKI-resistant lung cancer cells. © 2025 The Pathological Society of Great Britain and Ireland., (© 2025 The Pathological Society of Great Britain and Ireland.)

Background: Lung cancer remains a global health challenge, with an incidence of 23% and an overall 5-year survival of only 19%, as nearly half newly diagnosed cases are at the advanced stages. Among Asian patients, over 50% of lung cancer cases carry epidermal growth factor receptor ( EGFR ) mutations, highlighting the significance of targeted therapy, mainly EGFR tyrosine kinase inhibitors (TKIs). However, acquired resistance to EGFR -TKIs inevitably occurs, representing a persisting challenge in cancer therapy. Malignant pleural effusion, characterized by lack of blood circulation in the pleural cavity, is commonly found in patients who develop resistance to EGFR -TKIs. Therefore, with traditional drug administration methods, primarily oral or intravenous, drug concentration within the pleural cavity is often insufficient. Hence, traditional therapy, which consists of oral and intravenous medication, along with pleural cavity drainage, often fails to yield a satisfactory outcome., Case Description: We report a case in which hyperthermic intrathoracic chemotherapy (HITHOC) was administered in a 50-year-old male patient with malignant pleural effusion and resistance to third-generation TKIs. HITHOC significantly reduced the tumor burden of the patient and helped restore sensitivity to third-generation TKIs., Conclusions: We believe that HITHOC can efficiently improve the drug concentration within the pleural cavity, thereby reducing the tumor burden and eliminating potential TKI-resistant tumor subclones in the patient. This mode of therapy may prove valuable in overcoming TKI resistance., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tlcr.amegroups.com/article/view/10.21037/tlcr-2024-1252/coif). Y.Z.Z. reports funding from the Guangzhou Basic Research Project (No. 202201011326). The other authors have no conflicts of interest to declare., (Copyright © 2025 AME Publishing Company. All rights reserved.)

Background: Manoalide (MA), a proven natural inhibitor of PLA2 has anticancer effects, but its potential application and mechanism as an anticancer drug to promote EGFR-TKI sensitivity in lung cancer cells have not been studied.Methods: KRAS-mutated lung cancer cells and organoids, acquired osimertinib-resistant lung cancer cell lines HCC827OR, were used as EGFR-TKI-resistant models. CCK-8, clone formation, apoptosis assays, and calcein-AM staining were performed to investigate the inhibitory effects of MA in lung cancer cells and organoids. The flow cytometry or confocal microscope was used to detect lipid droplets, ROS, lipid peroxidation, mitochondria Ca2+, and iron content. The oxygen consumption rate (OCR) and fatty acid oxidation (FAO) were used to estimate the effect of MA on mitochondrial function.Results: MA inhibits the proliferation of KRAS-mutated lung cancer cells and organoids. In addition, MA induces ER stress in a ROS-dependent mechanism. The ROS induced by MA is mainly in mitochondrial and causes lipid peroxidation, thereby inhibiting mitochondrial FAO metabolism and promoting the accumulation of lipid droplets. MA also suppresses the KRAS-ERK pathway through ROS and promotes the sensitivity of KRAS-mutated lung cancer cells and organoids to osimertinib. Furthermore, MA induces ferroptosis by suppressing the NRF2-SLC7A11 axis and mitochondrial Ca2+ overload induced-FTH1 pathways to promote the sensitivity of osimertinib-resistant lung cancer cells to osimertinib.Conclusions: MA is a candidate EGFR-TKI sensitizer in KRAS-mutated and osimertinib-resistant lung cancer cells.

For patients exhibiting non-small-cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutations, epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are a first-line treatment. However, most patients who initially responded to EGFR-TKIs eventually developed acquired resistance, limiting the effectiveness of therapy. It has long been known that epithelial–mesenchymal transition (EMT) leads to acquired resistance to EGFR-TKIs in NSCLC. However, the mechanisms underlying the resistance dependent on EMT are unknown. This research aimed to reveal the effects of LMNA in the regulation of acquired resistance to erlotinib by EMT in NSCLC. The acquired erlotinib-resistant cells (HCC827/ER) were induced by gradual increase of concentrations of erlotinib in erlotinib-sensitive HCC827 cells. RNA sequencing and bioinformatics analysis were performed to uncover the involvement of LMNA in the EMT process that induced acquired resistance to erlotinib. The effect of LMNA on cell proliferation and migration was measured by clone-formation, wound-healing, and transwell assays, respectively. The EMT-related protein, nuclear shape and volume, and cytoskeleton changes were examined by immunofluorescence. Western blot was used to identify the underlying molecular mechanism of LMNA regulation of EMT. HCC827/ER cells with acquired resistance to erlotinib underwent EMT and exhibited lower LMNA expression compared to parental sensitive cells. LMNA negatively regulated the expression of EMT markers; HCC827/ER cells showed a significant up-regulation of mesenchymal markers, such as CDH2, SNAI2, VIM, ZEB1, and TWIST1. The overexpression of LMNA in HCC827/ER cells significantly inhibited EMT and cell proliferation, and this inhibitory effect of LMNA was enhanced in the presence of 2.5 μM erlotinib. Furthermore, a decrease in LMNA expression resulted in a higher nuclear deformability and cytoskeletal changes. In HCC827/ER cells, AKT, FGFR, ERK1/2, and c-fos phosphorylation levels were higher than those in HCC827 cells; Furthermore, overexpression of LMNA in HCC827/ER cells reduced the phosphorylation of AKT, ERK1/2, c-fos, and FGFR. In conclusion, our findings first demonstrated that downregulation of LMNA promotes acquired EGFR-TKI resistance in NSCLC with EGFR mutations by EMT. LMNA inhibits cell proliferation and migration of erlotinib-resistant cells via inhibition of the FGFR/MAPK/c-fos signaling pathway. These findings indicated LMNA as a driver of acquired resistance to erlotinib and provided important information about the development of resistance to erlotinib treatment in NSCLC patients with EGFR mutations. [ABSTRACT FROM AUTHOR]

Purpose: Although epidermal growth factor receptor (EGFR)-activating mutations in non-small cell lung cancer (NSCLC) usually show sensitivity to first-generation EGFR-tyrosine kinase inhibitors (TKIs), most patients relapse because of drug resistance. Heat shock protein 27 (HSP27) has been reported to be involved in the resistance of EGFR-TKIs, although the underlying mechanism is unclear. Here, we explore the mechanisms of HSP27-mediated EGFR TKI resistance and propose novel therapeutic strategies. Methods: To determine the mechanism of HSP27 associated gefitinib resistance, differences were assessed using gefitinib-sensitive and -resistant NSCLC cell lines. In vivo xenograft experiments were conducted to elucidate the combinatorial effects of J2, a small molecule HSP27 inhibitor, and gefitinib. Analyses of human NSCLC tissues and PDX tissues were also used for comparison of HSP27 and phosphorylated AKT expression. Results: Large-scale cohort analysis of NSCLC cases revealed that HSP27 expression correlated well with the incidence of EGFR mutations and affected patient survival. Increased pAKT and HSP27 was observed in gefitinib-resistant cells compared with gefitinib-sensitive cells. Moreover, increased phosphorylation of HSP27 by gefitinib augmented its protein stability and potentiated its binding activity with pAKT, which resulted in increased gefitinib resistance. However, in gefitinib-sensitive cells, stronger binding activity between EGFR and HSP27 was observed. Moreover, these phenomena occurred regardless of EGFR mutation including secondary mutations, such as T790M. AKT knockdown switched HSP27-pAKT binding to HSP27-EGFR, which promoted gefitinib sensitivity in gefitinib-resistant cells. Functional inhibition of HSP27 yielded sensitization to gefitinib in gefitinib-resistant cells by inhibiting the interaction between HSP27 and pAKT. Conclusions: Our results indicate that combination of EGFR-TKIs with HSP27 inhibitors may represent a good strategy to overcome resistance to EGFR-TKIs, especially in cancers exhibiting AKT pathway activation. [ABSTRACT FROM AUTHOR]

We report a case with a novel ALK-R3HDM1 and EML4-ALK dual fusion that might be a delicate mechanism for the acquired resistance of epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitor (TKI). A patient with EGFR L858R lung adenocarcinoma developed disease progression after 72.7 months of gefitinib therapy; rebiopsy was done, and next-generation sequencing showed the disappearance of the previous EGFR mutations. In addition, two new ALK fusions emerged, indicating that the emergence of dual ALK rearrangement may be the underlying mechanism of gefitinib resistance. The patient exhibits an excellent response to second-line alectinib treatment with a significant clinical benefit and a high quality of life. Finally, we summarized previous studies in which ALK fusion is a required resistance mechanism to EGFR-TKI.

Purpose: To evaluate the outcomes of immune checkpoint inhibitor (ICI)-based treatments versus classical chemotherapy for metastatic non-small cell lung cancer (NSCLC) patients who develop epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) resistance and to explore the population that may benefit from ICI-based therapy. Materials and methods: All patients who had previously received EGFR-TKI therapy at two cancer centers in China and developed resistance to targeted therapies were included. Progression-free survival (PFS) and overall survival (OS) were utilized to evaluate the outcomes of the study cohort. Results: A total of 132 patients were included. The median follow-up time for this cohort was 21.7 months (IQR, 14.8-28.8 months), calculated from the date of EGFR-TKI resistance. The median PFS and OS were 4.9 months (IQR, 2.8-9.2) and 13.5 months (IQR, 6.6-26.5 months), respectively. Multivariate analysis showed that ICI-based therapy could significantly improve OS when compared to the classic chemotherapy (hazard ratio [HR], 0.55; 95% CI, 0.34-0.88; P = 0.01) after adjusting for variables such as gender, age, mutation status, and brain or liver metastasis status. The combined modality of ICI plus chemotherapy could offer a long-term OS benefit in most subgroups, such as young (<65 years) patients, and those without secondary T790M mutations or absence of liver and brain metastases, and the populations with good Eastern Cooperative Oncology Group (ECOG) scores. Conclusion: For patients presenting with EGFR-TKI resistance, ICI-based therapy could offer a more favorable survival than classical chemotherapy. The combination of ICI with chemotherapy may be the optimal modality for those with good ECOG PS scores. [ABSTRACT FROM AUTHOR]

Non-small cell lung cancer (NSCLC) is the most common lung cancer subtype. Although chemotherapy and targeted therapy are used for the treatment of patients with NSCLC, the survival rate remains very low. Recent findings suggested that aurora kinase A (AKA), a cell cycle regulator, is a potential target for NSCLC therapy. Previously, we reported that a chemical entity of quinazolin-4(3H)-one represents a new template for AKA inhibitors, with antiproliferative activity against cancer cells. A quinazolin-4(3H)-one derivative was further designed and synthesized in order to improve the pharmacokinetic properties and antiproliferation activity against NSCLC cell lines. The derivative, BIQO-19 (Ethyl 6-(4-oxo-3-(pyrimidin-2-ylmethyl)-3,4-dihydroquinazolin-6-yl)imidazo [1,2-a]pyridine-2-carboxylate), exhibited improved solubility and antiproliferative activity in NSCLC cells, including epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI)-resistant NSCLC cells. BIQO-19 effectively inhibited the growth of the EGFR-TKI-resistant H1975 NSCLC cells, with the suppression of activated AKA (p-AKA) expression in these cells. The inhibition of AKA by BIQO-19 significantly induced G2/M phase arrest and subsequently evoked apoptosis in H1975 cells. In addition, the combination of gefitinib and BIQO-19 exhibited synergistic antiproliferative activity in NSCLC cells. These findings suggest the potential of BIQO-19 as a novel therapeutic agent for restoring the sensitivity of gefitinib in EGFR-TKI-resistant NSCLC cells. [ABSTRACT FROM AUTHOR]

PurposeTo evaluate the outcomes of immune checkpoint inhibitor (ICI)-based treatments versus classical chemotherapy for metastatic non-small cell lung cancer (NSCLC) patients who develop epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) resistance and to explore the population that may benefit from ICI-based therapy.Materials and methodsAll patients who had previously received EGFR-TKI therapy at two cancer centers in China and developed resistance to targeted therapies were included. Progression-free survival (PFS) and overall survival (OS) were utilized to evaluate the outcomes of the study cohort.ResultsA total of 132 patients were included. The median follow-up time for this cohort was 21.7 months (IQR, 14.8–28.8 months), calculated from the date of EGFR-TKI resistance. The median PFS and OS were 4.9 months (IQR, 2.8–9.2) and 13.5 months (IQR, 6.6–26.5 months), respectively. Multivariate analysis showed that ICI-based therapy could significantly improve OS when compared to the classic chemotherapy (hazard ratio [HR], 0.55; 95% CI, 0.34–0.88; P = 0.01) after adjusting for variables such as gender, age, mutation status, and brain or liver metastasis status. The combined modality of ICI plus chemotherapy could offer a long-term OS benefit in most subgroups, such as young (

Abstract Immunotherapy is considered one of the most important therapeutic strategies for patients with lung adenocarcinoma after the development of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR‐TKI) resistance. However, useful predictors of immunotherapy for these patients has not been examined well, although the status of the tumor immune microenvironment (TIME), including programmed death‐ligand 1 expression and lymphocyte infiltration, has been generally known to provide predictive markers for the efficacy of immunotherapy. This study aimed to clarify novel predictors of immunotherapy following EGFR‐TKI resistance in lung adenocarcinoma, especially regarding micro RNA (miRNA). We evaluated the correlation between EGFR‐TKI resistance and lymphocyte infiltration, before and after acquiring EGFR‐TKI resistance, in 21 cases of lung adenocarcinoma, and further explored this by in vitro studies, using miRNA PCR arrays. Subsequently, we transfected miRNA‐1 (miR‐1), the most variable miRNA in this array, into three kinds of lung cancer cells, and examined the effects of miR‐1 on EGFR‐TKI sensitivity, cytokine expression and lymphocyte migration. Histopathological examination demonstrated that infiltration levels of CD8‐positive T cells were significantly decreased after development of EGFR‐TKI resistance. In vitro studies revealed that miR‐1 significantly inhibited EGFR‐TKI effect and induction of cytokines, such as C‐C motif chemokine ligand 5 and C‐X‐C motif chemokine ligand 10, causing inhibition of monocyte migration. These results indicate that the upregulated miR‐1 might suppress the TIME, following development of EGFR‐TKI resistance. Therefore, miR‐1 could be a clinically useful marker to predict therapeutic efficacy of immunotherapy in lung adenocarcinoma patients with EGFR‐TKI resistance.

Introduction: Leptomeningeal metastasis (LM) commonly occurs in non-small cell lung cancer (NSCLC) patients and has a poor prognosis. Due to limited access to leptomeningeal lesions, the genetic characteristics of LM have not been explored to date. Cerebrospinal fluid (CSF) may be the most representative liquid biopsy medium to obtain genomic information from LM in NSCLC. Methods: CSF biopsies and matched peripheral blood biopsies were collected from 33 NSCLC patients with LM. We profiled genetic alterations from LM by comparing CSF cell-free DNA (cfDNA) with plasma cfDNA. Somatic mutations were examined using targeted sequencing. Genomic instability was analyzed by low-coverage whole-genome sequencing (WGS). Results: Driver mutations were detected in 100% of CSF cfDNA with much higher variant allele frequency than that in matched plasma cfDNA (57.5%). Furthermore, we found that the proportions of CSF cfDNA fragments below 150 bp were significantly higher than those in plasma cfDNA. These findings indicate enrichment of circulating tumor DNA (ctDNA) in CSF and explain the high sensitivity of mutation detection in the CSF. The absence of some mutations in CSF cfDNA—especially the first-/second-generation mutation T790M, which confers resistance to epidermal growth factor receptor (EGFR)-Tyrosine kinase inhibitors (TKIs)—that were present in plasma cfDNA samples indicates different mechanisms of cancer evolution between LM and extracranial lesions. In addition, 86.6% of CSF ctDNA samples revealed high levels of genomic instability compared with 2.5% in plasma cfDNA samples. A higher number of large-scale state transitions (LSTs) in CSF cfDNA were associated with a shorter overall survival (OS). Conclusion: Our results suggest that LM and extracranial lesions develop independently. Both CSF cfDNA genetic profiling and plasma cfDNA genetic profiling are necessary for clinical decision-making for NSCLC patients with LM. Through CSF-based low-coverage WGS, a high level of LSTs was identified as a potential biomarker of poor prognosis. [ABSTRACT FROM AUTHOR]

IntroductionLeptomeningeal metastasis (LM) commonly occurs in non-small cell lung cancer (NSCLC) patients and has a poor prognosis. Due to limited access to leptomeningeal lesions, the genetic characteristics of LM have not been explored to date. Cerebrospinal fluid (CSF) may be the most representative liquid biopsy medium to obtain genomic information from LM in NSCLC.MethodsCSF biopsies and matched peripheral blood biopsies were collected from 33 NSCLC patients with LM. We profiled genetic alterations from LM by comparing CSF cell-free DNA (cfDNA) with plasma cfDNA. Somatic mutations were examined using targeted sequencing. Genomic instability was analyzed by low-coverage whole-genome sequencing (WGS).ResultsDriver mutations were detected in 100% of CSF cfDNA with much higher variant allele frequency than that in matched plasma cfDNA (57.5%). Furthermore, we found that the proportions of CSF cfDNA fragments below 150 bp were significantly higher than those in plasma cfDNA. These findings indicate enrichment of circulating tumor DNA (ctDNA) in CSF and explain the high sensitivity of mutation detection in the CSF. The absence of some mutations in CSF cfDNA—especially the first-/second-generation mutation T790M, which confers resistance to epidermal growth factor receptor (EGFR)-Tyrosine kinase inhibitors (TKIs)—that were present in plasma cfDNA samples indicates different mechanisms of cancer evolution between LM and extracranial lesions. In addition, 86.6% of CSF ctDNA samples revealed high levels of genomic instability compared with 2.5% in plasma cfDNA samples. A higher number of large-scale state transitions (LSTs) in CSF cfDNA were associated with a shorter overall survival (OS).ConclusionOur results suggest that LM and extracranial lesions develop independently. Both CSF cfDNA genetic profiling and plasma cfDNA genetic profiling are necessary for clinical decision-making for NSCLC patients with LM. Through CSF-based low-coverage WGS, a high level of LSTs was identified as a potential biomarker of poor prognosis.

Objective: Epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI) is a first-line treatment for lung adenocarcinoma with EGFR-sensitive mutations, but acquired resistance to EGFR-TKIs remains a problem in clinical practice. The development of epithelial–mesenchymal transition (EMT) is a critical mechanism that induces acquired resistance to TKIs. Reversing acquired resistance to EGFR-TKIs through targeting the key molecules driving EMT provides an alternative choice for patients. We, therefore, aimed to explore the role of doublecortin-like kinase 1 (DCLK1) as an EMT driver gene in the acquired resistance of lung adenocarcinoma to EGFR-TKIs. Methods: The IC50 of Gefitinib or Osimertinib in PC9/HCC827 cells was measured using a cell counting kit-8 (CCK8) assay. The expression levels of EMT-related genes in PC9 and HCC827 cells were detected using RT-PCR and Western blot. Cell migration and invasion abilities were assessed via a transwell assay. For the in vivo experiments, PC9 cells were subcutaneously injected into BALB/c nude mice to form tumors. Upon harvesting, tumor tissues were retained for RT-PCR, Western blot, and polychromatic fluorescence staining to detect biomarker changes in the EMT process. Results: Gefitinib-resistant PC9 (PC9/GR) and Osimertinib-resistant HCC827 (HCC827/OR) cells showed remarkable activation of EMT and enhanced migration and invasion abilities compared to TKI-sensitive cells. In addition, DCLK1 expression was markedly increased in EGFR-TKI-resistant lung adenocarcinoma cells. The targeted knockout of DCLK1 effectively reversed the EMT phenotype in TKI-resistant cells and improved EGFR-TKI sensitivity, which was further validated by the in vivo experiments. Conclusions: DCLK1 facilitates acquired resistance to EGFR-TKI in lung adenocarcinoma by inducting EMT and accelerating the migration and invasion abilities of TKI-resistant cells.

Fusion of RET with different partner genes has been detected in papillary thyroid, lung, colorectal, pancreatic, and breast cancer. Approval of selpercatinib for treatment of lung and thyroid cancer with RET gene mutations or fusions calls for studies to explore RET fusion partners and their eligibility for RET‐based targeted therapy. In this study, RET fusion patterns in a large group of Chinese cancer patients covering several cancer types were identified using next‑generation sequencing. A total of 44 fusion patterns were identified in the study cohort with KIF5B, CCDC6, and ERC1 being the most common RET fusion partners. Notably, 17 novel fusions were first reported in this study. Prevalence of functional RET fusions was 1.05% in lung cancer, 6.03% in thyroid cancer, 0.39% in colorectal cancer, and less than 0.1% in gastric cancer and hepatocellular carcinoma. Analysis showed a preference for fusion partners in different tumor types, with KIF5B being the common type in lung cancer, CCDC6 in thyroid cancer, and NCOA4 in colorectal cancer. Co‐occurrence of EGFR mutations and RET fusions with rare partner genes (rather than KIF5B) in lung cancer patients was correlated with epidermal growth factor receptor‐tyrosine kinase inhibitor resistance and could predict response to targeted therapies. Findings from this study provide a guide to clinicians in determining tumors with specific fusion patterns as candidates for RET targeted therapies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Few trials have evaluated the utility of liquid biopsies to detect epidermal growth factor receptor mutations (EGFRm) at the time of response evaluation and its association with the clinical characteristics and outcomes of non-small-cell lung cancer (NSCLC) patients. OBJECTIVE: This study aimed to evaluate, in a real-world clinical setting, the prevalence of plasma EGFRm and its association with the clinical characteristics, response and survival outcomes of NSCLC patients under treatment with EGFR-tyrosine kinase inhibitors (EGFR-TKIs). METHODS: This observational study enrolled advanced or metastatic NSCLC patients, with confirmed tumor EGFRm, receiving treatment with first- or second-generation EGFR-TKIs. Blood samples for the detection of plasma EGFRm were collected at the time of response evaluation and processed using the Target Selector™ assay. The main outcomes were the detection rate of plasma EGFRm, median Progression-Free Survival (PFS) and Overall Survival (OS) according to plasma EGFR mutational status. RESULTS: Of 84 patients, 50 (59.5%) had an EGFRm detected in plasma. After a median follow-up of 21.1 months, 63 patients (75%) had disease progression. The detection rate of plasma EGFRm was significantly higher in patients with disease progression than in patients with partial response or stable disease (68.3% versus 33.3%; P < 0.01). PFS and OS were significantly longer in patients without plasma EGFRm than among patients with plasma EGFRm (14.3 months [95% CI, 9.25–19.39] vs 11.0 months [95% CI, 8.61–13.46]; P = 0.034) and (67.8 months [95% CI, 39.80–95.94] vs 32.0 months [95% CI, 17.12–46.93]; P = 0.006), respectively. A positive finding in LB was associated with the presence of ⩾ 3 more metastatic sites (P = 0.028), elevated serum carcinoembryonic (CEA) at disease progression (P = 0.015), and an increase in CEA with respect to baseline levels (P = 0.038). CONCLUSIONS: In NSCLC patients receiving EGFR-TKIs, the detection of plasma EGFRm at the time of tumor response evaluation is associated with poor clinical outcomes. [ABSTRACT FROM AUTHOR]

Histone deacetylase 6 (HDAC6) is a promising target for cancer treatment because it regulates cell mobility, protein trafficking, cell growth, apoptosis, and metastasis. However, the mechanism of HDAC6-induced anticancer drug resistance is unclear. In this study, we evaluated the anticancer effect of ACY-241, an HDAC6-selective inhibitor, on erlotinib-resistant pancreatic cancer cells that overexpress HDAC6. Our data revealed that ACY-241 hyperacetylated the HDAC6 substrate, α-tubulin, leading to a significant reduction in cell viability of erlotinib-resistant pancreatic cells, BxPC3-ER and HPAC-ER. Notably, a synergistic anticancer effect was observed in cells that received combined treatment with ACY-241 and erlotinib. Combined treatment effectively induced autophagy and inhibited autophagy through siLC3B, and siATG5 alleviated ACY-241-mediated cell death, as reflected by the recovery of PARP cleavage and apoptosis rates. In addition, combined ACY-241 and erlotinib treatment induced autophagy and subsequently, cell death by reducing AKT–mTOR activity and increasing phospho-AMPK signaling. Therefore, HDAC6 may be involved in the suppression of autophagy and acquisition of resistance to erlotinib in ER pancreatic cancer cells. ACY-241 to overcome erlotinib resistance could be an effective therapeutic strategy against pancreatic cancer. [ABSTRACT FROM AUTHOR]

BackgroundMET proto-oncogene amplification (amp) is an important mechanism underlying acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, the optimal treatment strategy after acquiring MET-amp-mediated EGFR-TKI resistance remains controversial. Our study compared three treatment strategies for patients with EGFR-mutant non-small-cell lung cancer (NSCLC) who were detected with MET-amp at EGFR-TKI progression using next-generation sequencing.MethodsOf the 70 patients included in the study, 38 received EGFR-TKI + crizotinib, 10 received crizotinib monotherapy, and 22 received chemotherapy. Clinical outcomes and molecular profiles were analyzed.ResultsThe objective response rate was 48.6% for EGFR-TKI + crizotinib group, 40.0% for crizotinib monotherapy group, and 18.2% for chemotherapy group. Patients who received EGFR-TKI + crizotinib had significantly longer progression-free survival than those who received crizotinib or chemotherapy (5.0 vs. 2.3 vs. 2.9 months, p = 0.010), but overall survival was comparable (10.0 vs. 4.1 vs. 8.5 months, p = 0.088). TP53 mutation (58.5%) and EGFR-amp (42.9%) were frequent concurrent mutations of the cohort. Progression-free survival was significantly longer for patients with either concurrent TP53 mutation (n = 17) (6.0 vs. 2.3 vs. 2.9 months, p = 0.009) or EGFR-amp (n = 13) (5.0 vs. 1.2 vs. 2.4 months, p = 0.016) in the EGFR-TKI + crizotinib group than the other two regimen. Potential acquired resistance mechanisms to EGFR-TKI + crizotinib included EGFR-T790M (n = 2), EGFR-L718Q (n = 1), EGFR-S645C (n = 1), MET-D1228H (n = 1), BRAF-V600E (n = 1), NRAS-Q61H (n = 1), KRAS-amp (n = 1), ERBB2-amp (n = 1), CDK4-amp (n = 1), and MYC-amp (n = 1).ConclusionOur study provides real-world clinical evidence from a large cohort that simultaneous inhibition of EGFR and MET could be a more effective therapeutic strategy for patients with MET-amp acquired from EGFR-TKI therapy.

Background: MET proto-oncogene amplification (amp) is an important mechanism underlying acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, the optimal treatment strategy after acquiring MET- amp-mediated EGFR-TKI resistance remains controversial. Our study compared three treatment strategies for patients with EGFR -mutant non-small-cell lung cancer (NSCLC) who were detected with MET- amp at EGFR-TKI progression using next-generation sequencing. Methods: Of the 70 patients included in the study, 38 received EGFR-TKI + crizotinib, 10 received crizotinib monotherapy, and 22 received chemotherapy. Clinical outcomes and molecular profiles were analyzed. Results: The objective response rate was 48.6% for EGFR-TKI + crizotinib group, 40.0% for crizotinib monotherapy group, and 18.2% for chemotherapy group. Patients who received EGFR-TKI + crizotinib had significantly longer progression-free survival than those who received crizotinib or chemotherapy (5.0 vs. 2.3 vs. 2.9 months, p = 0.010), but overall survival was comparable (10.0 vs. 4.1 vs. 8.5 months, p = 0.088). TP53 mutation (58.5%) and EGFR- amp (42.9%) were frequent concurrent mutations of the cohort. Progression-free survival was significantly longer for patients with either concurrent TP53 mutation (n = 17) (6.0 vs. 2.3 vs. 2.9 months, p = 0.009) or EGFR- amp (n = 13) (5.0 vs. 1.2 vs. 2.4 months, p = 0.016) in the EGFR-TKI + crizotinib group than the other two regimen. Potential acquired resistance mechanisms to EGFR-TKI + crizotinib included EGFR -T790M (n = 2), EGFR- L718Q (n = 1), EGFR -S645C (n = 1), MET -D1228H (n = 1), BRAF -V600E (n = 1), NRAS -Q61H (n = 1), KRAS- amp (n = 1), ERBB2- amp (n = 1), CDK4- amp (n = 1), and MYC- amp (n = 1). Conclusion: Our study provides real-world clinical evidence from a large cohort that simultaneous inhibition of EGFR and MET could be a more effective therapeutic strategy for patients with MET- amp acquired from EGFR-TKI therapy. [ABSTRACT FROM AUTHOR]

While significant upregulation of GRP78 has been documented in lung cancer patients, its association with resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) remains underexamined. Our study aimed to elucidate the functional importance of GRP78 in acquired resistance to EGFR-TKIs in non-small cell lung cancer (NSCLC) and to evaluate its potential as a therapeutic target. Immunoblot analysis or flow cytometry was employed to assess several markers for endoplasmic reticulum (ER) stress and apoptosis. Ru(II) complex I and HA15, two known GRP78 inhibitors, were used to evaluate the functional role of GRP78. A Xenograft assay was performed to evaluate the in vivo anti-cancer effects of the GRP78 inhibitors. We validated a significant increase in GRP78 protein levels in HCC827-GR, H1993-GR, and H1993-ER cells. The EGFR-TKI-resistant cells overexpressing GRP78 exhibited significantly higher cell proliferation rates than did their parental counterparts. Notably, GRP78 inhibition resulted in a more profound anti-proliferative and apoptotic response via heightened ER stress and subsequent reactive oxygen species (ROS) production in EGFR-TKI-resistant cell lines compared with their parental cells. In xenograft models implanted with HCC827-GR, both Ru(II) complex I and HA15 significantly suppressed tumor growth and reduced tumor weight. Additionally, we confirmed that GRP78 plays a critical role in the proliferation of H1975, an EGFR-TKI-resistant T790M-mutant cell line, relative to other NSCLC cell lines. Our findings strongly support targeting of GRP78 as a promising therapeutic strategy for NSCLC patients with acquired resistance to EGFR-TKIs. [Display omitted] • GRP78 protein expression was significantly elevated in acquired EGFR-TKI resistant lung cancer cells compared to parental cells. • Acquired EGFR-TKI resistant cells showed a substantial dependency on GRP78 for cell proliferation. • In EGFR-TKI resistant cells, GRP78 inhibition resulted in apoptosis through ROS generation and elevation of ER stress. • GRP78 inhibition suppressed tumor growth in HCC827-GR engrafting mouse model. [ABSTRACT FROM AUTHOR]

Abstract Background Although EGFR tyrosine kinase inhibitors (EGFR-TKIs) are beneficial to lung adenocarcinoma patients with sensitive EGFR mutations, resistance to these inhibitors induces a cancer stem cell (CSC) phenotype. Here, we clarify the function and molecular mechanism of shisa3 as a suppressor that can reverse EGFR-TKI resistance and inhibit CSC properties. Methods The suppresser genes involved in EGFR-TKI resistance were identified and validated by transcriptome sequencing, quantitative real-time PCR (qRT-PCR) and immunohistochemistry. Biological function analyses, cell half maximal inhibitory concentration (IC50), self-renewal, and migration and invasion capacities, were detected by CCK8, sphere formation and Transwell assays. Tumorigenesis and therapeutic effects were investigated in nonobese diabetic/severe combined immunodeficiency (nod-scid) mice. The underlying mechanisms were explored by Western blot and immunoprecipitation analyses. Results We found that low expression of shisa3 was related to EGFR-TKI resistance in lung adenocarcinoma patients. Ectopic overexpression of shisa3 inhibited CSC properties and the cell cycle in the lung adenocarcinoma cells resistant to gefitinib/osimertinib. In contrast, suppression of shisa3 promoted CSC phenotypes and the cell cycle in the cells sensitive to EGFR-TKIs. For TKI-resistant PC9/ER tumors in nod-scid mice, overexpressed shisa3 had a significant inhibitory effect. In addition, we verified that shisa3 inhibited EGFR-TKI resistance by interacting with FGFR1/3 to regulate AKT/mTOR signaling. Furthermore, combinational administration of inhibitors of FGFR/AKT/mTOR and cell cycle signaling could overcome EGFR-TKI resistance associated with shisa3-mediated CSC capacities in vivo. Conclusion Taken together, shisa3 was identified as a brake to EGFR-TKI resistance and CSC characteristics, probably through the FGFR/AKT/mTOR and cell cycle pathways, indicating that shisa3 and concomitant inhibition of its regulated signaling may be a promising therapeutic strategy for reversing EGFR-TKI resistance.

Abstract Background The development of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) has dramatically improved the prognosis of patients with EGFR-mutant non-small-cell lung cancer (NSCLC). The purpose of this study is to investigate the clinical outcome with or without EGFR-TKI resistance before WBRT and the sequence between EGFT-TKIs and whole brain radiotherapy (WBRT) of EGFR-mutant NSCLC patients who developed multiple brain metastases (BMs). Patients and methods Three hundred forty-four EGFR-mutant NSCLC patients with multiple BMs were reviewed. Enrolled patients were divided into TKI-naïve group and TKI-resistant group. The intracranial progression-free survival (PFS) and overall survival (OS) were analyzed via the Kaplan-Meier method. Results For patients with multiple BMs treated by WBRT, the median intracranial PFS and OS were longer in the TKI-naïve group than those in the TKI-resistant group, but there were no statistically significant between two groups (Intracranial PFS: 7.7 vs. 5.4 months, p = 0.052; OS: 11.2 vs. 9.2 months, p = 0.106). For patients with Lung-molGPA 0–2, no significant differences in median intracranial PFS (6.2 vs. 5.2 months, p = 0.123) and OS (7.8 vs. 6.7 months, p = 0.514) between TKI-naïve and TKI-resistant groups. For patients with Lung-molGPA 2.5–4, intracranial PFS: 12.8 vs. 10.1 months; OS: 23.3 vs. 15.3 months. Conclusions Our study found that there were no difference in intracranial PFS and OS in all patients between the two groups of TKI-naïve and TKI-resistant. But for patients in subgroup of Lung-molGPA 2.5–4, there were a better intracranial PFS and OS in TKI-naïve group.

Background Re‐biopsy is important for exploring resistance mechanisms, especially for non‐small cell lung cancer (NSCLC) patients who develop resistance to EGFR‐tyrosine kinase inhibitors (TKIs). Liquid biopsy using circulating tumor DNA has come into use for this purpose. This retrospective study investigated the status of re‐biopsy and liquid biopsy in NSCLC patients with EGFR mutations and evaluated their effect on clinical strategies and prognosis. Methods Five hundred fifty‐five NSCLC patients with resistance to EGFR‐TKIs were included and divided into three groups: re‐biopsy, liquid biopsy, and no re‐biopsy. Amplification refractory mutation system (ARMS) PCR or super ARMS PCR was used to detect EGFR mutations. Results Three hundred eight (55.5%) patients underwent re‐biopsy; 45.5% (140/308) were positive for T790M. The most common re‐biopsy procedure was computed tomography‐guided percutaneous core needle biopsy (60.1%), followed by effusion drainage (29.5%) and superficial lymph node biopsy (6.5%). One hundred eighteen (21.3%) patients underwent liquid biopsy; the T790M detection rate was 41.5% (49/118.) Of the 308 patients who underwent re‐biopsy, 69 were examined for EGFR mutations with plasma. The concordance rate of T790M detection between tissue and plasma was 66.7%. A statistical difference in further treatment after EGFR‐TKI failure was observed among all groups (P = 0.014). Patients in the biopsy groups were more likely to receive third‐generation EGFR‐TKIs. Multivariate analysis showed that re‐biopsy had a significant impact on overall survival (P

Abstract Background Non-small cell lung cancer (NSCLC) patients with sensitive epidermal growth factor receptor (EGFR) mutations are successfully treated with EGFR tyrosine kinase inhibitors (EGFR-TKIs); however, resistance to treatment inevitably occurs. Given lipid metabolic reprogramming is widely known as a hallmark of cancer and intimately linked with EGFR-stimulated cancer growth. Activation of EGFR signal pathway increased monounsaturated fatty acids (MUFA) and lipid metabolism key enzyme Stearoyl-CoA Desaturase 1 (SCD1) expression. However the correlation between EGFR-TKI resistance and lipid metabolism remains to be determined. Methods In this study the differences in lipid synthesis between paired TKI-sensitive and TKI-resistant patient tissues and NSCLC cell lines were explored. Oleic acid (OA, a kind of MUFA, the SCD1 enzymatic product) was used to simulate a high lipid metabolic environment and detected the affection on the cytotoxic effect of TKIs (Gefitinib and osimertinib) in cell lines with EGFR-activating mutations. (20S)-Protopanaxatriol (g-PPT), an aglycone of ginsenosides, has been reported to be an effective lipid metabolism inhibitor, was used to inhibit lipid metabolism. Additionally, synergism in cytotoxic effects and signal pathway activation were evaluated using CCK-8 assays, Western blotting, flow cytometry, Edu assays, plate clone formation assays and immunofluorescence. Furthermore, two xenograft mouse models were used to verify the in vitro results. Results Gefitinib-resistant cells have higher lipid droplet content and SCD1 expression than Gefitinib-sensitive cells in both NSCLC cell lines and patient tissues. Additionally oleic acid (OA, a kind of MUFA, the SCD1 enzymatic product) abrogates the cytotoxic effect of both Gefitinib and osimertinib in cell lines with EGFR-activating mutations. As a reported effective lipid metabolism inhibitor, g-PPT significantly inhibited the expression of SCD1 in lung adenocarcinoma cells, and then down-regulated the content of intracellular lipid droplets. Combined treatment with Gefitinib and g-PPT reverses the resistance to Gefitinib and inhibits the activation of p-EGFR and the downstream signaling pathways. Conclusions Our findings uncover a link between lipid metabolic reprogramming and EGFR-TKI resistance, confirmed that combination target both EGFR and abnormal lipid metabolism maybe a promising therapy for EGFR-TKI resistance and highlighting the possibility of monitoring lipid accumulation in tumors for predicting drug resistance.

BackgroundEpidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are effective in advanced EGFR-mutation non-small cell lung cancer (NSCLC) but the magnitude of tumor regression varies, and drug resistance is unavoidable. The pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) levels are reduced or lost and acts as a tumor suppressor in many cancers. Here, we hypothesized that PHLPP is a key regulator of EGFR-TKI sensitivity and a potential treatment target for overcoming resistance to EGFR-TKI in lung cancer.MethodsCell proliferation and growth inhibition were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assay. PHLPP- knockdown stable cell lines were generated by lentivirus-mediated delivery of PHLPP shRNAs. The expression of PHLPP mRNA and protein levels was detected by real-time quantitative polymerase chain reaction (qPCR) and Western blotting. Immunohistochemical (IHC) staining was performed to detect the PHLPP expression in clinical patient tissue samples. A transcriptomic assay of genome-wide RNA expressions of PHLPP in NSCLC cell lines according to gefitinib sensitivity was obtained from Gene Expression Omnibus (GEO) database. Murine xenograft model was established to verify the function of PHLPP in gefitinib resistance in vivo.ResultsPHLPP highly expressed in gefitinib-sensitive NSCLC cell lines than gefitinib-resistant NSCLC cell lines. In gefitinib-acquired resistance cell line HCC827-GR, PHLPP expression even dramatically reduced. Knockdown of PHLPP in NSCLC cells decreased cell death induced by the EGFR-TKI, while overexpression PHLPP in gefitinib-resistance NSCLC cells can enhance or restore EGFR-TKIs sensitivity. Mechanism study indicated that PHLPP downregulation attenuates the effect of EGFR-TKI on the both AKT and ERK pathway, thereby decreasing the cell death sensitivity to EGFR inhibitors. In xenograft mice, knockdown of PHLPP decreased tumor response to gefitinib and advanced tumor cells re-growth after gefitinib treatment. In clinical, PHLPP expression were reduced in the post-relapse tumor compared to that of pre-treatment, and lower pre-treatment PHLPP levels were significantly correlated with shorter progression-free survival (PFS) in patients with EGFR-mutant lung adenocarcinoma whom treated with EGFR-TKI.ConclusionsOur data strongly demonstrated that loss of PHLPP function was a key factor of EGFR-TKI resistance in NSCLC. Downregulated PHLPP expression activated PI3K-AKT and MAPK-ERK pathway which strengthened cell survival to EGFR-TKI. Therefore, PHLPP expression level was not only a potential biomarker to predict EGFR-TKIs sensitivity but also as a therapeutic target in EGFR-TKIs therapy, enhancing PHLPP expression may be a valuable strategy for delaying or overcoming EGFR-TKIs drug resistance.

Background: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are effective in advanced EGFR-mutation non-small cell lung cancer (NSCLC) but the magnitude of tumor regression varies, and drug resistance is unavoidable. The pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) levels are reduced or lost and acts as a tumor suppressor in many cancers. Here, we hypothesized that PHLPP is a key regulator of EGFR-TKI sensitivity and a potential treatment target for overcoming resistance to EGFR-TKI in lung cancer. Methods: Cell proliferation and growth inhibition were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assay. PHLPP- knockdown stable cell lines were generated by lentivirus-mediated delivery of PHLPP shRNAs. The expression of PHLPP mRNA and protein levels was detected by real-time quantitative polymerase chain reaction (qPCR) and Western blotting. Immunohistochemical (IHC) staining was performed to detect the PHLPP expression in clinical patient tissue samples. A transcriptomic assay of genome-wide RNA expressions of PHLPP in NSCLC cell lines according to gefitinib sensitivity was obtained from Gene Expression Omnibus (GEO) database. Murine xenograft model was established to verify the function of PHLPP in gefitinib resistance in vivo. Results: PHLPP highly expressed in gefitinib-sensitive NSCLC cell lines than gefitinib-resistant NSCLC cell lines. In gefitinib-acquired resistance cell line HCC827-GR, PHLPP expression even dramatically reduced. Knockdown of PHLPP in NSCLC cells decreased cell death induced by the EGFR-TKI, while overexpression PHLPP in gefitinib-resistance NSCLC cells can enhance or restore EGFR-TKIs sensitivity. Mechanism study indicated that PHLPP downregulation attenuates the effect of EGFR-TKI on the both AKT and ERK pathway, thereby decreasing the cell death sensitivity to EGFR inhibitors. In xenograft mice, knockdown of PHLPP decreased tumor response to gefitinib and advanced tumor cells re-growth after gefitinib treatment. In clinical, PHLPP expression were reduced in the post-relapse tumor compared to that of pre-treatment, and lower pre-treatment PHLPP levels were significantly correlated with shorter progression-free survival (PFS) in patients with EGFR-mutant lung adenocarcinoma whom treated with EGFR-TKI. Conclusions: Our data strongly demonstrated that loss of PHLPP function was a key factor of EGFR-TKI resistance in NSCLC. Downregulated PHLPP expression activated PI3K-AKT and MAPK-ERK pathway which strengthened cell survival to EGFR-TKI. Therefore, PHLPP expression level was not only a potential biomarker to predict EGFR-TKIs sensitivity but also as a therapeutic target in EGFR-TKIs therapy, enhancing PHLPP expression may be a valuable strategy for delaying or overcoming EGFR-TKIs drug resistance. [ABSTRACT FROM AUTHOR]

Synchronous malignant mesothelioma (MM) and lung carcinoma are extremely rare in patients without a history of asbestos exposure and poses tremendous difficulties in clinical management. We report a patient without asbestos exposure diagnosed with MM during EGFR-TKI treatment of lung adenocarcinoma (LUAD), who responded to first-line chemotherapy with pemetrexed plus carboplatin and failed to subsequent systemic therapy. Clinicians should be careful about the possibility of MM comorbidity in LUAD patients whose lesions respond differently to EGFR-TKI, even in those without a history of asbestos exposure.

Background: The 14-3-3ζ protein, which acts as a putative oncoprotein, has been found to promote the proliferation, metastasis, and chemoresistance of cancer cells in several cancers including lung adenocarcinoma (LUAD); however, its significance in epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI) resistance remains unknown.Methods: The Cancer Genome Atlas (TCGA) database was used to determine 14-3-3ζ expression in pancancer and LUAD. 14-3-3ζ and ID1 expression was then examined in clinical LUAD samples by immunohistochemistry (IHC). Lentiviral transfection with 14-3-3ζ-specific small hairpin RNA (shRNA) was used to establish stable 14-3-3ζ knockdown gefitinib-resistant PC9 (PC9/GR) and H1975 cell lines. The effect of 14-3-3ζ knockdown on reversing EGFR-TKI resistance was determined in vitro by Cell Counting Kit-8 (CCK-8), wound healing, Transwell assays, and flow cytometry. A xenograft tumor model was established to evaluate the role of 14-3-3ζ in EGFR-TKI resistance. Microarray analysis results showed multiple pathways regulated by 14-3-3ζ-shRNA.Results: In the present study, we demonstrated that based on the TCGA, pancancer and LUAD 14-3-3ζ expression was elevated and predicted unfavorable prognosis. In addition, high 14-3-3ζ expression was associated with advanced T stage, TNM stage, presence of lymph node metastasis and, importantly, poor treatment response to EGFR-TKIs in LUAD patients with EGFR-activating mutations. 14-3-3ζ shRNA sensitized EGFR-TKI-resistant human LUAD cells to gefitinib and reversed epithelial-to-mesenchymal transition (EMT). After 14-3-3ζ depletion, bone morphogenetic protein (BMP) signaling activation was decreased in EGFR-TKI-resistant cells in microarray analysis, which was further validated by Western blot analysis. Furthermore, the expression of 14-3-3ζ positively correlates with ID1 expression in human EGFR-mutant LUAD patient samples. In vivo, there was a reduction in the tumor burden in mice treated with 14-3-3ζ shRNA and gefitinib compared to mice treated with gefitinib alone.Conclusion: Our work uncovers a hitherto unappreciated role of 14-3-3ζ in EGFR-TKI resistance. This study might provide a potential therapeutic approach for treating LUAD patients harboring EGFR mutations.

Abstract Background Epithelial‐to‐mesenchymal transition (EMT) plays a pivotal role in resistance to EGFR tyrosine kinase inhibitors (TKIs) in non‐small‐cell lung cancer (NSCLC). Our previous study revealed that in osteosarcoma, human apurinic/apyrimidinic endonuclease 1 (APE1) regulates transforming growth factor‐β (TGF‐β), an important player in EMT. We therefore hypothesized a link between APE1 and EGFR‐TKI responsiveness in NSCLC. Methods The protein levels of APE1 were analyzed in tumors of NSCLC patients receiving EGFR‐TKI treatment. The correlation between APE1 expression and progression‐free survival (PFS), overall survival (OS), or response rate were analyzed. The impact of APE1 on the response to EGFR‐TKIs was measured by exogenous manipulation of APE1 in EGFR‐TKI‐sensitive and EGFR‐TKI‐resistant cells. Results We indicate that low expression of APE1 in tumors is associated with a significantly longer PFS (20.8 months vs 8.4 months, P = 0.008) and a preferential OS (39.0 months vs 17.0 months, P = 0.001), with no difference in initial response rate to EGFR‐TKIs. We observed that APE1 protein level was significantly increased in EGFR‐TKI‐resistant cells and was associated with downregulated E‐cadherin and upregulated vimentin. The EMT phenotype, as well as the levels of TGF‐β, was suppressed in APE1 knockdown HCC827/IR and PC‐9/ER cells, while the EMT phenotype was promoted in APE1‐overexpressed HCC827 and PC‐9 cells. Furthermore, a specific APE1 redox inhibitor (ie, E3330) effectively reversed the EMT phenotype and further sensitized the cells to EGFR‐TKIs. Conclusion This study revealed a significant role of APE1 in EGFR‐TKI resistance via novel regulatory effects on the EMT phenotype in NSCLC.

Immunotherapy is considered one of the most important therapeutic strategies for patients with lung adenocarcinoma after the development of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR‐TKI) resistance. However, useful predictors of immunotherapy for these patients has not been examined well, although the status of the tumor immune microenvironment (TIME), including programmed death‐ligand 1 expression and lymphocyte infiltration, has been generally known to provide predictive markers for the efficacy of immunotherapy. This study aimed to clarify novel predictors of immunotherapy following EGFR‐TKI resistance in lung adenocarcinoma, especially regarding micro RNA (miRNA). We evaluated the correlation between EGFR‐TKI resistance and lymphocyte infiltration, before and after acquiring EGFR‐TKI resistance, in 21 cases of lung adenocarcinoma, and further explored this by in vitro studies, using miRNA PCR arrays. Subsequently, we transfected miRNA‐1 (miR‐1), the most variable miRNA in this array, into three kinds of lung cancer cells, and examined the effects of miR‐1 on EGFR‐TKI sensitivity, cytokine expression and lymphocyte migration. Histopathological examination demonstrated that infiltration levels of CD8‐positive T cells were significantly decreased after development of EGFR‐TKI resistance. In vitro studies revealed that miR‐1 significantly inhibited EGFR‐TKI effect and induction of cytokines, such as C‐C motif chemokine ligand 5 and C‐X‐C motif chemokine ligand 10, causing inhibition of monocyte migration. These results indicate that the upregulated miR‐1 might suppress the TIME, following development of EGFR‐TKI resistance. Therefore, miR‐1 could be a clinically useful marker to predict therapeutic efficacy of immunotherapy in lung adenocarcinoma patients with EGFR‐TKI resistance. [ABSTRACT FROM AUTHOR]