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Induction of ferroptosis, a recently defined form of nonapoptotic cell death caused by iron-dependent lipid peroxidation, has emerged as an anticancer strategy. Erastin is a ferroptosis activator that promotes cell death that not only depends on the depletion of cellular cysteine but also relies on mitochondrial oxidative metabolism of glutamine. Here, we demonstrate that ASS1, a key enzyme involved in the urea cycle, plays a crucial role in ferroptosis resistance. Loss of ASS1 increased the sensitivity of non–small cell lung cancer (NSCLC) cells to erastin in vitro and decreased tumor growth in vivo. Metabolomics analysis with stable isotope-labeled glutamine showed that ASS1 promotes reductive carboxylation of cytosolic glutamine and compromises the oxidative tricarboxylic acid cycle from glutamine anaplerosis, reducing mitochondrial-derived lipid reactive oxygen species. Moreover, transcriptome sequencing showed that ASS1 activates the mTORC1–SREBP1–SCD5 axis to promote de novo monounsaturated fatty acid synthesis by using acetyl-CoA derived from the glutamine reductive pathway. Treating ASS1-deficient NSCLC cells with erastin combined with arginine deprivation significantly enhanced cell death compared with either treatment alone. Collectively, these results reveal a previously unknown regulatory role of ASS1 in ferroptosis resistance and provide a potential therapeutic target for ASS1-deficient NSCLC. Significance: ASS1 promotes reductive carboxylation of glutamine and confers ferroptosis resistance, providing multiple treatment options for ASS1-deficient non–small cell lung cancer.

Supplementary Figures and Figure Legends

Supplementary Table 1 Primer sequences

Induction of ferroptosis, a recently defined form of nonapoptotic cell death caused by iron-dependent lipid peroxidation, has emerged as an anticancer strategy. Erastin is a ferroptosis activator that promotes cell death that not only depends on the depletion of cellular cysteine but also relies on mitochondrial oxidative metabolism of glutamine. Here, we demonstrate that ASS1, a key enzyme involved in the urea cycle, plays a crucial role in ferroptosis resistance. Loss of ASS1 increased the sensitivity of non–small cell lung cancer (NSCLC) cells to erastin in vitro and decreased tumor growth in vivo. Metabolomics analysis with stable isotope-labeled glutamine showed that ASS1 promotes reductive carboxylation of cytosolic glutamine and compromises the oxidative tricarboxylic acid cycle from glutamine anaplerosis, reducing mitochondrial-derived lipid reactive oxygen species. Moreover, transcriptome sequencing showed that ASS1 activates the mTORC1–SREBP1–SCD5 axis to promote de novo monounsaturated fatty acid synthesis by using acetyl-CoA derived from the glutamine reductive pathway. Treating ASS1-deficient NSCLC cells with erastin combined with arginine deprivation significantly enhanced cell death compared with either treatment alone. Collectively, these results reveal a previously unknown regulatory role of ASS1 in ferroptosis resistance and provide a potential therapeutic target for ASS1-deficient NSCLC.Significance:ASS1 promotes reductive carboxylation of glutamine and confers ferroptosis resistance, providing multiple treatment options for ASS1-deficient non–small cell lung cancer.

c-Myc overexpression increased the expression and shedding of CA125

c-Myc overexpression increased the expression and shedding of CA125

ERK was involved in c-Myc expression in pancreatic cancer cells

Supplementary Table S1. Primers sequences used in the real-time PCR. Supplementary Table S2. siRNA oligoes used in the study. Supplementary Table S3. Primers sequences used in the quantitative ChIP. Supplementary Table S4. Clinicopathological features and correlation of MUC16 expression in PDAC in the TCGA cohorts. Supplementary Table S5. Univariate and multivariate Cox regression of Overall survival for patients with PDAC in the TCGA cohorts. Supplementary Table S6. Clinicopathological features and correlation of MUC16 expression in PDAC in the FUSCC cohorts. Supplementary Table S7. Univariate and multivariate Cox regression of Overall survival for patients with PDAC in the FUSCC cohorts.

FBW7 was involved in the expression and shedding of CA125

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with the 5-year survival rate less than 6%. Previous results indicated that serum levels of CA125 (encoded by MUC16) could be used to predict which groups of pancreatic cancer patients may benefit from surgery. However, the underlying mechanism remains elusive. Herein, using the Cancer Genome Atlas and clinicopathologic data obtained from our center, we demonstrate that high CA125 serum levels and expression levels of MUC16 are predictive of poor prognosis. MUC16 is also validated as a downstream target of KRAS, and their expression strongly correlated with each other in vitro and in vivo. Mechanistically, the KRAS/ERK axis induced upregulation of MUC16 and shedding of CA125 via its effector c-Myc in SW1990 and PANC-1 pancreatic cancer cells. Notably, proto-oncogene c-Myc could bind to the promoter of MUC16 and transcriptionally activate its expression. Taken together, these data establish CA125 as a prognostic marker for pancreatic cancer, and mechanistic studies uncovered the KRAS/c-Myc axis as a driving factor for upregulation of MUC16.Implications: The current study uncovers the contribution of oncogenic KRAS to serum marker CA125 production through a mechanism that involves the ERK/c-Myc axis. Mol Cancer Res; 15(2); 201–12. ©2016 AACR.

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Methylthioadenosine phosphorylase (MTAP) is a key enzyme associated with the salvage of methionine and adenine that is deficient in 20% to 30% of pancreatic cancer. Our previous study revealed that MTAP deficiency indicates a poor prognosis for patients with pancreatic ductal adenocarcinoma (PDAC). In this study, bioinformatics analysis of The Cancer Genome Atlas (TCGA) data indicated that PDACs with MTAP deficiency display a signature of elevated glycolysis. Metabolomics studies showed that that MTAP deletion–mediated metabolic reprogramming enhanced glycolysis and de novo purine synthesis in pancreatic cancer cells. Western blot analysis revealed that MTAP knockout stabilized hypoxia-inducible factor 1α (HIF1α) protein via posttranslational phosphorylation. RIO kinase 1 (RIOK1), a downstream kinase upregulated in MTAP-deficient cells, interacted with and phosphorylated HIF1α to regulate its stability. In vitro experiments demonstrated that the glycolysis inhibitor 2-deoxy-d-glucose (2-DG) and the de novo purine synthesis inhibitor l-alanosine synergized to kill MTAP-deficient pancreatic cancer cells. Collectively, these results reveal that MTAP deficiency drives pancreatic cancer progression by inducing metabolic reprogramming, providing a novel target and therapeutic strategy for treating MTAP-deficient disease.Significance:This study demonstrates that MTAP status impacts glucose and purine metabolism, thus identifying multiple novel treatment options against MTAP-deficient pancreatic cancer.

Pancreatic cancer (PC) is one of the most deadly diseases, and its incidence is increasing year by year. The methyltransferase SETD8 has been demonstrated to play an important role in tumor cell proliferation and metastasis. However, little is known about whether SETD8 could affect the invasion and metastasis of PC and the mechanism underlying the regulation. Based on our previous report, here, we further found that SETD8 could promote the invasion and migration of PC cells by inducing the expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1). ROR1 was predominantly upregulated in PC tissues and was correlated with lymph node metastasis and worse prognosis. Mechanistically, SETD8 mediated ROR1 activity and regulated PC cells invasion and migration, although promoting the expression of stemness and epithelial-mesenchymal transition-related molecules. This promotion effect disappeared when the catalytically inactive mutant SETD8 was overexpressed, which could be counteracted by the SETD8-specific methyltransferase inhibitor UNC0379. Collectively, our results demonstrate that SETD8 may be a novel prognostic factor and a therapeutic target of PC.

Methylthioadenosine phosphorylase (MTAP) is a key enzyme associated with the salvage of methionine and adenine that is deficient in 20% to 30% of pancreatic cancer. Our previous study revealed that MTAP deficiency indicates a poor prognosis for patients with pancreatic ductal adenocarcinoma (PDAC). In this study, bioinformatics analysis of The Cancer Genome Atlas (TCGA) data indicated that PDACs with MTAP deficiency display a signature of elevated glycolysis. Metabolomics studies showed that that MTAP deletion–mediated metabolic reprogramming enhanced glycolysis and de novo purine synthesis in pancreatic cancer cells. Western blot analysis revealed that MTAP knockout stabilized hypoxia-inducible factor 1α (HIF1α) protein via posttranslational phosphorylation. RIO kinase 1 (RIOK1), a downstream kinase upregulated in MTAP-deficient cells, interacted with and phosphorylated HIF1α to regulate its stability. In vitro experiments demonstrated that the glycolysis inhibitor 2-deoxy-d-glucose (2-DG) and the de novo purine synthesis inhibitor l-alanosine synergized to kill MTAP-deficient pancreatic cancer cells. Collectively, these results reveal that MTAP deficiency drives pancreatic cancer progression by inducing metabolic reprogramming, providing a novel target and therapeutic strategy for treating MTAP-deficient disease. Significance: This study demonstrates that MTAP status impacts glucose and purine metabolism, thus identifying multiple novel treatment options against MTAP-deficient pancreatic cancer.

The incidence of cervical cancer (CC) ranks the fourth in female malignant tumors globally. Chemoresistance is one of the main causes of treatment failure in advanced recurrent CC. Prolyl isomerase 1 (PIN1) is overexpressed in a variety of tumors, and is closely associated with the malignant potential of tumor cells, such as transformation, proliferation, invasion and metastasis. In the present study, we demonstrate that cell death induced by suppression of PIN1 could be inhibited by ferrostatin-1 (Fer-1) and ferroptosis biomarkers including lactate dehydrogenase (LDH) release, lipid peroxidation and malondialdehyde (MDA) are upregulated by downregulating PIN1. We then discover that abrogation of PIN1 greatly decreases the level of glutathione peroxidase 4 (GPX4) and the level of PIN1 is positively correlated with the level of GPX4. Furthermore, the knockdown of PIN1 promotes ferroptosis induced by RSL3. The mechanism involves PIN1 silencing which downregulates GPX4 by decreasing the level of nuclear factor E2-related factor 2 (NRF2). Furthermore, overexpression of NRF2 inhibits RSL3-mediated ferroptosis of CC cells when PIN1 is silenced. In addition, our results indicate that cisplatin (DDP) induces ferroptosis, which is restrained by overexpression of PIN1. The PIN1 inhibitor, KPT-6566, promotes the cytotoxic effect of DDP. The present study reveals that PIN1 affects ferroptosis and sensitivity to DDP in CC cells via the NRF2/GPX4 axis, thereby identifying PIN1 as a potential therapeutic target for CC.

Constitutive ERK1/2 activation has been frequently observed in pancreatic adenocarcinoma (PDAC). How ERK1/2 activation status been potentiated and maintained by epigenetic mechanisms has seldom been discussed in PDAC. In this study, we first examined the expression status of p-ERK1/2 in PDAC tissues by immunohistochemical staining and then screened possible epigenetic factors that displayed different expression status between p-ERK1/2 high and low groups by RNA profiling, and found that SETD8 displayed an increased expressional pattern in p-ERK1/2high patient group. Then the impact of SETD8 on the proliferation of PDAC cells were investigated on the basis of gain or loss-of-function assays. RNA sequencing assays were performed to screen potential SETD8 downstream targets that contribute to ERK1/2 activation. Mass spectrometry and transcriptional analysis, including dual-luciferase assay and chromatin immunoprecipitation assay (ChIP), were used to explore the molecular mechanisms that governing SETD8-mediated ERK1/2 activation. In vitro cell line studies and in vivo xenograft mouse model studies indicated that SETD8 promoted cell proliferation and increased tumor formation capacity of PDAC cell lines. Mechanism explorations uncovered that SETD8 suppressed the expression of DUSP10, which was responsible for dephosphorylation of ERK1/2. Mass spectrometry and transcriptional analysis results demonstrated that STAT3 interacted with SETD8 and recruited SETD8 to the promoter region of DUSP10, leading to epigenetic silencing of DUSP10 and the resultant activation of ERK1/2. In conclusion, SETD8 interacts with STAT3 on DUSP10 promoter region and epigenetically silences DUSP10 expression. Decreased DUSP10 expression in PDAC potentiates activation of ERK1/2 phosphorylation, resulting in unfavorable prognosis of PDAC.

Evidence suggests that tripartite motif-containing 2 (TRIM2) is associated with carcinogenic effects in several malignancies. However, the expression patterns and roles of TRIM2 in pancreatic cancer are rarely studied. Our study demonstrated that TRIM2 was expressed in a high percentage of pancreatic tumors. High TRIM2 expression was negatively correlated with the outcome of pancreatic cancer. TRIM2 silencing significantly inhibited the proliferation, migration, invasion, and in vivo tumorigenicity of pancreatic cancer cells. Regarding the mechanism involved, TRIM2 activated ROS-related E2-related factor 2 (NRF2)/antioxidant response element (ARE) signaling and the integrin/focal adhesion kinase (FAK) pathway. Treatment of pancreatic cancer cells with the antioxidant N-acetyl-L-cysteine decreased ROS activity and expression level of NRF2 and ITGB7. Increased translocation of NRF2 protein into nucleus further rescued the inhibited ITGB7 transcription. Moreover, NRF2 bound to the potential ARE on the promoter region and enhanced the transcriptional activity of ITGB7, indicating the bridging effect of NRF2 between the two signaling pathways. In summary, our study provides evidence that upregulated TRIM2 in pancreatic cancer predicts short survival for pancreatic cancer patients. TRIM2 accelerates pancreatic cancer progression via the ROS-related NRF2/ITGB7/FAK axis.

The ubiquitin-proteasome system is an important post-translational modification system involved in numerous biological processes, such as cell cycle regulation, gene transcription, signal transduction, apoptosis, differentiation and development. F-box/WD repeat-containing protein 7 (FBXW7) is one of the most studied F-box (FBX) proteins, serving as substrate recognition component of S phase kinase-associated protein 1-Cullin 1-FBX protein complexes. As a tumor suppressor, FBXW7 recognizes numerous proto-oncoproteins and promotes their ubiquitination and subsequent proteasomal degradation. FBXW7 is regulated at different levels, leading to tunable and specific control of the activity and abundance of its substrates. Therefore, genetic mutations or decreases in its expression serve an important biological role in tumor development. In-depth studies and identification of additional substrates targeted by FBXW7 have suggested a signaling network regulated by FBXW7, including its tumor-inhibitory role. The present review focused on the role of FBXW7 in tumor suppression and its application in cancer therapy.

Background The introduction of laparoscopic technology has greatly promoted the development of surgery, and the trend of minimally invasive surgery is becoming more and more obvious. However, there is no consensus as to whether laparoscopic pancreaticoduodenectomy (LPD) should be performed routinely. Main body We summarized the development of laparoscopic pancreaticoduodenectomy (LPD) in recent years by comparing with open pancreaticoduodenectomy (OPD) and robotic pancreaticoduodenectomy (RPD) and evaluated its feasibility, perioperative, and long-term outcomes including operation time, length of hospital stay, estimated blood loss, and overall survival. Then, several relevant issues and challenges were discussed in depth. Conclusion The perioperative and long-term outcomes of LPD are no worse and even better in length of hospital stay and estimated blood loss than OPD and RPD except for a few reports. Though with strict control of indications, standardized training, and learning, ensuring safety and reducing cost are still and will always the keys to the healthy development of LPD; the best times for it are coming.

Pancreatic cancer remains a challenging disease with an overall cumulative 5-year survival rate around 6%. Though significant progress has been made in the availability of diagnostic techniques and treatment strategies, pancreatic cancer remains a disease of high mortality rate. Therefore, there is an urgent need for a better understanding of the molecular mechanisms that governs the oncogenesis and metastasis process of pancreatic cancer. In the present study, by using the Cancer Genome Atlas (TCGA) dataset analysis, we demonstrated that sorting nexin 6 (SNX6) serves as a biomarker for predicting prognosis of pancreatic cancer. In vitro studies demonstrated that silencing of SNX6 expression reduced cell proliferation, colony formation, invasion, and metastasis. Higher level of SNX6 helps maintain the mesenchymal properties, which renders migration and invasive capacities to pancreatic cancer cells. Moreover, in the process of TGF-β-induced epithelial to mesenchymal transition (EMT), the expression level of SNX6 was increased, and silencing of SNX6 expression could inhibit the TGF-β-induced EMT program. These results collectively uncovered a novel predictive marker for pancreatic cancer and provided the possible underlying molecular mechanism.

Fibroblast growth factor-binding protein 1 (FGFBP1) promotes fibroblast growth factor (FGF) activity by releasing FGFs from extracellular matrix storage. We previously reported that the tumor suppressor F-box and WD repeat domain-containing 7 suppresses FGFBP1 by reducing expression of c-Myc, which inhibits the proliferation and migration of pancreatic cancer cells. However, the potential mechanism by which FGFBP1 facilitates pancreatic ductal adenocarcinoma (PDAC) remains unexplored. In this study, we focused on the function of FGFBP1 in the interplay between cancer-associated fibroblasts (CAFs) and pancreatic cancer cells (PCCs). Decreased FGF22 expression was detected in CAFs co-cultured with PCCs with FGFBP1 abrogation, which was verified in the cell culture medium by enzyme-linked immunosorbent assay. Active cytokine FGF22 significantly facilitated the migration and invasion of PANC-1 and Mia PaCa-2 cells. The number of penetrating PCCs cocultured with CAFs with FGF22 abrogation was significantly less than that of the control group. Interestingly, higher expressions of FGF22 and fibroblast growth factor receptor 2 (FGFR2) were associated with worse prognosis of patients with PDAC and FGFR2, an independent prognostic marker of PDAC. The PANC-1 and Mia PaCa-2 cells with silenced FGFR2 showed weaker invasion and metastasis, even if these cells were simultaneously treated with cytokine FGF22. These results revealed that FGFBP1-mediated interaction between CAFs and PCCs via FGF22/FGFR2 facilitates the migration and invasion of PCCs. FGFR2 could act as a prognostic marker for patients with PDAC.

Objectives Accumulated evidence suggests that Pin1 contributes to oncogenesis of diverse cancers. However, the underlying mechanism of oncogenic function of Pin1 in PDAC requires further exploration. Materials and Methods IHC was performed using PDAC tissues. Western blot, PCR, immunofluorescence and transwell were performed using cell lines. GSEA were applied for possible downstream pathways. ChIP assay and dual luciferase were used for assessment of transcriptional activity. Results Both Pin1 and IL‐18 levels are increased in primary PDAC tissues and that their levels are positively correlated. High expression of IL‐18 is a predictor of poor prognoses. Pin1 promoted pancreatic cancer cell proliferation and motility by increasing IL‐18 expression, while Pin1 knockdown also inhibited the tumour‐promoting effect of IL‐18. Both Pin1 and IL‐18 could enhance the NFκB activity in pancreatic cancer cells. When bound to the p65 protein, Pin1 promoted p65 phosphorylation and its nuclear translocation. In the nucleus, Pin1 and p65 simultaneously bound to the IL‐18 promoter and enhanced IL‐18 transcription. In addition, recruitment of p65 to the IL‐18 promoter was decreased in Pin1‐silenced cells. Conclusions Our study improves the understanding of Pin1 in tumour‐promoting inflammation in PDAC, which is a hallmark of cancer; Pin1 interacted with p65 in PDAC and enhanced NF‐κB signalling and downstream transcriptional activation of IL‐18, with increased IL‐18 continuously activating NF‐κB signalling, which then forms a positive feedback loop.

Methylthioadenosine phosphorylase (MTAP) is a key enzyme associated with the salvage of methionine and adenine that is deficient in 20% to 30% of pancreatic cancer. Our previous study revealed that MTAP deficiency indicates a poor prognosis for patients with pancreatic ductal adenocarcinoma (PDAC). In this study, bioinformatics analysis of The Cancer Genome Atlas (TCGA) data indicated that PDACs with MTAP deficiency display a signature of elevated glycolysis. Metabolomics studies showed that that MTAP deletion-mediated metabolic reprogramming enhanced glycolysis and

OBJECTIVES To investigate the correlation between lymph node metastasis (LNM) and various clinicopathological features of pancreatic neuroendocrine tumors (pNETs) and its impact on prognosis. METHODS We searched the Surveillance Epidemiology and End Results database (2004-2015) for patients with surgically treated pNETs. Factors correlated with LNMs were analyzed by logistic regression and by Cox analysis. RESULTS For tumors of 1 to 4 cm, age (P < 0.001, P = 0.014), grade (P < 0.001, P < 0.001), LNMs (P = 0.008, P < 0.001), and size (P = 0.038, P = 0.002) predicted overall survival (OS) and disease-specific survival (DSS). For tumor greater than 4 cm, age (P < 0.001, P = 0.001) and grade (P = 0.011, P = 0.048) were independent prognostic factors of OS and DSS. Lymph node metastasis modestly predicted DSS (P = 0.028) but not OS (P = 0.218). CONCLUSIONS In pNETs greater than 4 cm, LNM is not a predictor of OS and modestly predicts DSS, and lymphadenectomy may be unhelpful in these patients. For pNETs 1 to 4 cm, LNM predicts poor OS and DSS, which supports lymphadenectomy in these patients. Pancreas-sparing resection with only limited peripancreatic node sampling needs to be questioned.

ADP Ribosylation Factor 6 (ARF6) is a part of the RAS superfamily and regulates vesicular trafficking, remodeling of membrane lipids, and signaling pathways. Our previous study has found that ARF6, functioned as a downstream of Kras/ERK signaling pathway, could promote proliferation and Warburg effect in pancreatic cancer cells. Moreover, ARF6 is promising to be a biomarker for predicting prognosis of pancreatic cancer. Ferroptosis is a new defined iron-dependent form of nonapoptotic cell death, which is closely related to Kras mutation. Therefore, it is urgent to further explore the relationship between ARF6 and ferroptosis. Our study demonstrated that ARF6 did not directly regulate lipid peroxidation, but endowed pancreatic cancer cells to a status that is sensitive to oxidative stress, especially RSL3-induced lipid peroxidation. Further study revealed that ARF6 could also regulate gemcitabine resistance via multiple pathways. In conclusion, ARF6 has a profound effect on pancreatic cancer development.

Ferroptosis is a recently defined, non‐apoptotic, regulated cell death (RCD) process that comprises abnormal metabolism of cellular lipid oxides catalysed by iron ions or iron‐containing enzymes. In this process, a variety of inducers destroy the cell redox balance and produce a large number of lipid peroxidation products, eventually triggering cell death. However, in terms of morphology, biochemistry and genetics, ferroptosis is quite different from apoptosis, necrosis, autophagy‐dependent cell death and other RCD processes. A growing number of studies suggest that the relationship between ferroptosis and cancer is extremely complicated and that ferroptosis promises to be a novel approach for the cancer treatment. This article primarily focuses on the mechanism of ferroptosis and discusses the potential application of ferroptosis in cancer therapy.

The secreted fibroblast growth factor (FGF) binding protein (FGF-BP), which is an extracellular chaperone molecule for FGFs, has been demonstrated to enhance the biological and biochemical activities of FGFs and to be closely related to the growth of several cancers. However, the role of FGFBP1 in pancreatic adenocarcinoma (PDAC) has not been studied extensively. We previously reported that decreased FBW7 could induce pancreatic cancer proliferation and progression. In the present study, we investigated whether FBW7 inhibited cell proliferation and metastasis by decreasing the expression of FGFBP1 in pancreatic cancer. We initially confirmed that pancreatic cancer patients with higher FGFBP1 expression had a worse prognosis. Next, we demonstrated that FGFBP1 silencing inhibited the proliferation and metastasis of PANC-1 and Mia PaCa-2 cells. Mechanistically, FGFBP1 was negatively correlated with FBW7 but positively correlated with c-Myc in PDAC tissue samples, and FBW7 regulated FGFBP1 in a c-Myc-dependent manner. We also found that FBW7 silencing could partly reverse the effect of FGFBP1 silencing on proliferation and metastasis. In summary, FGFBP1 is a prognostic marker for overall survival and is required for pancreatic cancer cell proliferation and metastasis, which is mediated by FBW7 in a c-Myc-dependent manner. Thus, targeting the FBW7/c-Myc/FGFBP1 axis might suppress recurrence and metastasis and provide novel treatment strategies for PDAC.

Pancreatic ductal adenocarcinoma (PDAC) constitutes one of the most challenging lethal tumors and has a very poor prognosis. In addition to cancer cells, the tumor microenvironment created by a repertoire of resident and recruited cells and the extracellular matrix also contribute to the acquisition of hallmarks of cancer. Among these factors, cancer-associated fibroblasts (CAFs) are critical components of the tumor microenvironment. CAFs originate from the activation of resident fibroblasts and pancreatic stellate cells, the differentiation of bone marrow-derived mesenchymal stem cells and epithelial-to-mesenchymal transition. CAFs acquire an activated phenotype via various cytokines and promote tumor proliferation and growth, accelerate invasion and metastasis, induce angiogenesis, promote inflammation and immune destruction, regulate tumor metabolism, and induce chemoresistance; these factors contribute to the acquisition of major hallmarks of PDAC. Therefore, an improved understanding of the impact of CAFs on the major hallmarks of PDAC will highlight the diagnostic and therapeutic values of these targeted cells.

F-box and WD repeat domain-containing 7 (FBW7) has been characterized as a tumor suppressor, and its mutation or decreased expression has been observed in many types of human cancers. Our recent studies have uncovered that in pancreatic cancer, the KRAS mutation decreased FBW7 expression through phosphorylation and subsequent ubiquitination. Moreover, FBW7 inhibited aerobic glycolysis in pancreatic cancer via induction of thioredoxin-interacting protein (TXNIP), a mitochondrial localized tumor suppressor. The roles of FBW7 in anti-apoptosis and drug resistance via proteosomal degradation of myeloid cell leukemia-1 (MCL-1), which is an anti-apoptotic factor have been reported. However, the role of FBW7 in the chemotherapeutic resistance of pancreatic cancer to gemcitabine has seldom been reported. In the present study, we demonstrated that overexpression of FBW7 in pancreatic cancer cells rendered increased sensitivity to gemcitabine. Mechanistically, FBW7 promoted gemcitabine sensitivity via upregulation of equilibrative nucleoside transporter 1 (ENT1) at the protein level rather than the transcriptional level. In depth analysis demonstrated that the ENT1 protein level could be increased by lysosome inhibition. Taken together, our results demonstrated that FBW7 could be a target for improving the therapeutic efficacy of gemcitabine by induction of ENT1.

Though significant progress has been made in the availability of diagnostic techniques and treatment strategies, pancreatic cancer remains a disease of high mortality rates. Therefore, there is an urgent need for a better understanding of the molecular mechanisms that governs the oncogenesis and metastasis process of pancreatic cancer. In our study, by using the Cancer Genome Atlas (TCGA) dataset analysis, we demonstrated that the small guanosine triphosphatase (GTPase) ADP-ribosylation factor 6 (ARF6) serves as a biomarker for predicting prognosis of pancreatic cancer. In vitro studies demonstrated that silencing ARF6 expression reduced cell proliferation and attenuated the Warburg effect. Moreover, we observed that ARF6 was a downstream target of Kras/ERK signaling pathway, and the strong correlation of expression between Kras and ARF6 in the TCGA dataset further confirmed this observation. Taken together, our novel findings suggest ARF6, a target of mutant Kras, may promote pancreatic cancer development by enhancing the Warburg effect.

Metabolic reprogramming is one of the emerging hallmarks of cancers. As a highly malignant tumor, pancreatic ductal adenocarcinoma (PDA) is not only a metabolic disease but also a heterogeneous disease. Heterogeneity induces PDA dependence on distinct nutritive substrates, thereby inducing different metabolic phenotypes. We stratified PDA into four phenotypes with distinct types of energy metabolism, including a Warburg phenotype, a reverse Warburg phenotype, a glutaminolysis phenotype, and a lipid-dependent phenotype. The four phenotypes possess distinct metabolic features and reprogram their metabolic pathways to adapt to stress. The metabolic type present in PDA should prompt differential imaging and serologic metabolite detection for diagnosis and prognosis. The targeting of an individual metabolic phenotype with corresponding metabolic inhibitors is considered a promising therapeutic approach and, in combination with chemotherapy, is expected to be a novel strategy for PDA treatment.

Background The epigenetic factor protein arginine methyltransferase 5 (PRMT5) has been reported to play vital roles in a wide range of cellular processes, such as gene transcription, genomic organization, differentiation and cell cycle control. However, its role in pancreatic cancer remains unclear. Our study aimed to investigate the roles of PRMT5 in pancreatic cancer prognosis and progression and to explore the underlying molecular mechanism. Methods Real-time PCR, immunohistochemistry and analysis of a dataset from The Cancer Genome Atlas (TCGA) were performed to study the expression of PRMT5 at the mRNA and protein levels in pancreatic cancer. Cell proliferation assays, including cell viability, colony formation ability and subcutaneous mouse model assays, were utilized to confirm the role of PRMT5 in cell proliferation and tumorigenesis. A Seahorse extracellular flux analyzer, a glucose uptake kit, a lactate level measurement kit and the measurement of 18F-FDG (fluorodeoxyglucose) uptake by PET/CT (positron emission tomography/computed tomography) imaging were used to verify the role of PRMT5 in aerobic glycolysis, which sustains cell proliferation. The regulatory effect of PRMT5 on cMyc, a master regulator of oncogenesis and aerobic glycolysis, was explored by quantitative PCR and protein stability measurements. Results PRMT5 expression was significantly upregulated in pancreatic cancer tissues compared with that in adjacent normal tissues. Clinically, elevated expression of PRMT5 was positively correlated with worse overall survival in pancreatic cancer patients. Silencing PRMT5 expression inhibited the proliferation of pancreatic cancer cells both in vitro and in vivo. Moreover, PRMT5 regulated aerobic glycolysis in vitro in cell lines, in vivo in pancreatic cancer patients and in a xenograft mouse model used to measure 18F-FDG uptake. We found that mechanistically, PRMT5 posttranslationally regulated cMyc stability via F-box/WD repeat-containing protein 7 (FBW7), an E3 ubiquitin ligase that controls cMyc degradation. Moreover, PRMT5 epigenetically regulated the expression of FBW7 in pancreatic cancer cells. Conclusions The present study demonstrated that PRMT5 epigenetically silenced the expression of the tumor suppressor FBW7, leading to increased cMyc levels and the subsequent enhancement of the proliferation of and aerobic glycolysis in pancreatic cancer cells. The PRMT5/FBW7/cMyc axis could be a potential therapeutic target for the treatment of pancreatic cancer. Electronic supplementary material The online version of this article (10.1186/s12964-019-0344-4) contains supplementary material, which is available to authorized users.

Background Hepatocyte nuclear factor 4α (HNF4α) is a tissue-specific transcription factor that regulates the expression of numerous genes in hepatocytes and pancreatic β cells. HNF4α has been reported to affect cell proliferation and chemoresistance in several cancers. However, the role of HNF4α in pancreatic adenocarcinoma (PDAC) has not been studied extensively and remains unclear. Methods By utilizing immunohistochemical (IHC) staining, we measured the expression of HNF4α in PDAC tissues. By silencing HNF4α in PDAC cell lines, we assessed the impact of HNF4α on pancreatic cancer cell proliferation and gemcitabine sensitivity. We used CCK8 and colony formation assays to examine the effect of HNF4α on cell proliferation. A flow cytometry assay was used to assess cell apoptosis. The expression of gemcitabine-related genes was detected by quantitative real‑time PCR (qRT-PCR) and Western blotting. IHC was utilized to assess the correlation between HNF4α and human equilibrative nucleoside transporter 1 (hENT1) expression in PDAC patients. Chromatin immunoprecipitation (ChIP) and dual‑luciferase reporter assays were used to confirm that hENT1 is a target gene of HNF4α. Results Increased HNF4α expression was detected in PDAC tissues; patients with higher HNF4α expression displayed worse prognosis. To elucidate the function of HNF4α, we examined its role in pancreatic cancer cell proliferation, apoptosis and gemcitabine resistance. In HNF4α-silenced Capan-1 and MiaPaCa-2 cells, we observed decreased cell proliferation and increased sensitivity to gemcitabine compared to those of controls. The mechanism of HNF4α in gemcitabine-related chemosensitivity was then explored. In response to HNF4α silencing, the expression levels of gemcitabine-related proteins, hENT1 and deoxycytidine kinase (dCK) were significantly increased. Additionally, hENT1 was negatively correlated with HNF4α in PDAC tissue samples. Moreover, we identified hENT1 as a downstream target of HNF4α. Conclusion HNF4α is a prognostic marker for overall survival, is required for pancreatic cancer cell proliferation and promotes resistance to gemcitabine by downregulating hENT1. Therefore, targeting HNF4α might reverse gemcitabine resistance and provide novel treatment strategies for PDAC. Electronic supplementary material The online version of this article (10.1186/s12935-019-0767-4) contains supplementary material, which is available to authorized users.

UHRF1 (ubiquitin like with plant homeodomain and ring finger domains 1) is an epigenetic modifier that is overexpressed in some cancers, including pancreatic cancer, and mediates silencing of tumor suppressor genes. However, the role of UHRF1 in regulating pancreatic cancer metabolism and metastasis is not clear. In the present study, we demonstrated that silencing UHRF1 significantly inhibited aerobic glycolysis in pancreatic cancer cells. Furthermore, we demonstrated that UHRF1 knockdown decreased hypoxia inducible factor (HIF)1α levels and HIF1α targeted glycolytic genes. The Cancer Genome Atlas dataset analysis supported this observation. The Sirtuin (SIRT) family members regulate aerobic glycolysis in many cancers. We analyzed the correlation between UHRF1 and SIRT3-5 expression and found a significant negative correlation between UHRF1 and SIRT4. Further transcriptional and functional analysis demonstrates that SIRT4 is a downstream target of UHRF1 and negatively regulated aerobic glycolysis, cell proliferation and tumor growth. Our study identified a novel UHRF1/SIRT4 axis in regulation of pancreatic cancer cell proliferation, metabolism, and metastasis.