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Cyclin E, a regulatory subunit of cyclin-dependent kinase 2 (CDK2), is central to the initiation of DNA replication at the G1/S checkpoint. Tight temporal control of cyclin E is essential to the coordination of cell-cycle processes and the maintenance of genome integrity. Overexpression of cyclin E in human tumors was first observed in the 1990s and led to the identification of oncogenic roles for deregulated cyclin E in experimental models. A decade later, low-molecular-weight cyclin E (LMW-E) isoforms were observed in aggressive tumor subtypes. Compared with full-length cyclin E, LMW-E hyperactivates CDK2 through increased complex stability and resistance to the endogenous inhibitors p21CIP1 and p27KIP1 LMW-E is predominantly generated by neutrophil elastase-mediated proteolytic cleavage, which eliminates the N-terminal cyclin E nuclear localization signal and promotes cyclin E's accumulation in the cytoplasm. Compared with full-length cyclin E, the aberrant localization and unique stereochemistry of LMW-E dramatically alters the substrate specificity and selectivity of CDK2, increasing tumorigenicity in experimental models. Cytoplasmic LMW-E, which can be assessed by IHC, is prognostic of poor survival and predicts resistance to standard therapies in patients with cancer. These patients may benefit from therapeutic modalities targeting the altered biochemistry of LMW-E or its associated vulnerabilities. Cancer Res; 78(19); 5481-91. ©2018 AACR.

Investigating sex differences in cancer will improve therapy for both sexes and discover sex-specific protective mechanisms. Two recent analyses by Lopes-Ramos and colleagues and Li and colleagues point to specific gene regulatory networks and genomic alterations associated with sex differences in tumor incidence and progression. Integrating this information with emerging concepts about sex biases in the genome may help focus attention on factors that shift the odds for tumor growth. Cancer Res; 78(19); 5504-5. ©2018 AACR See related articles by Li et al., p. 5527, and Lopes-Ramos et al., p. 5538.

Chronic inflammation is a serious risk factor for cancer; however, the routes from inflammation to cancer are poorly understood. On the basis of the processes implicated by frequently mutated genes associated with inflammation and cancer in three organs (stomach, colon, and liver) extracted from the Gene Expression Omnibus, The Cancer Genome Atlas, and Gene Ontology databases, we present a multiscale model of the long-term evolutionary dynamics leading from inflammation to tumorigenesis. The model incorporates cross-talk among interactions on several scales, including responses to DNA damage, gene mutation, cell-cycle behavior, population dynamics, inflammation, and metabolism-immune balance. Model simulations revealed two stages of inflammation-induced tumorigenesis: a precancerous state and tumorigenesis. The precancerous state was mainly caused by mutations in the cell proliferation pathway; the transition from the precancerous to tumorigenic states was induced by mutations in pathways associated with apoptosis, differentiation, and metabolism-immune balance. We identified opposing effects of inflammation on tumorigenesis. Mild inflammation removed cells with DNA damage through DNA damage-induced cell death, whereas severe inflammation accelerated accumulation of mutations and hence promoted tumorigenesis. These results provide insight into the evolutionary dynamics of inflammation-induced tumorigenesis and highlight the combinatorial effects of inflammation and metabolism-immune balance. This approach establishes methods for quantifying cancer risk, for the discovery of driver pathways in inflammation-induced tumorigenesis, and has direct relevance for early detection and prevention and development of new treatment regimes. Cancer Res; 77(22); 6429-41. ©2017 AACR.

Chronic inflammation is a serious risk factor for cancer; however, the routes from inflammation to cancer are poorly understood. On the basis of the processes implicated by frequently mutated genes associated with inflammation and cancer in three organs (stomach, colon, and liver) extracted from the Gene Expression Omnibus, The Cancer Genome Atlas, and Gene Ontology databases, we present a multiscale model of the long-term evolutionary dynamics leading from inflammation to tumorigenesis. The model incorporates cross-talk among interactions on several scales, including responses to DNA damage, gene mutation, cell-cycle behavior, population dynamics, inflammation, and metabolism-immune balance. Model simulations revealed two stages of inflammation-induced tumorigenesis: a precancerous state and tumorigenesis. The precancerous state was mainly caused by mutations in the cell proliferation pathway; the transition from the precancerous to tumorigenic states was induced by mutations in pathways associated with apoptosis, differentiation, and metabolism-immune balance. We identified opposing effects of inflammation on tumorigenesis. Mild inflammation removed cells with DNA damage through DNA damage-induced cell death, whereas severe inflammation accelerated accumulation of mutations and hence promoted tumorigenesis. These results provide insight into the evolutionary dynamics of inflammation-induced tumorigenesis and highlight the combinatorial effects of inflammation and metabolism-immune balance. This approach establishes methods for quantifying cancer risk, for the discovery of driver pathways in inflammation-induced tumorigenesis, and has direct relevance for early detection and prevention and development of new treatment regimes. Cancer Res; 77(22); 6429-41. ©2017 AACR.

Circular extrachromosomal DNA (ecDNA), a common mechanism of oncogene amplification, has been identified as a major contributor to intratumoral heterogeneity and patient outcomes. In a recent publication in Nature Genetics, Chapman and colleagues further explored the role of ecDNA in the context of medulloblastoma. Using whole-genome sequencing, they found that 18% of the patients carry ecDNA amplification across a 468 medulloblastoma patient cohort. The presence of ecDNA was associated with worse survival. Single-cell FISH imaging and multiomic sequencing revealed that ecDNA copy number displayed a cell-to-cell variability within the sample, contributing to tumor heterogeneity. Furthermore, through sequencing and CRISPRi experiments, the authors uncovered frequent enhancer rewiring events on ecDNA that drive proliferation., (©2024 American Association for Cancer Research.)

Metastasis is a major cause of morbidity and mortality in patients with cancer, highlighting the need to identify improved treatment and prevention strategies. Previous observations in preclinical models and tumors from patients with small cell lung cancer (SCLC), a fatal form of lung cancer with high metastatic potential, identified the transcription factor NFIB as a driver of tumor growth and metastasis. However, investigation into the requirement for NFIB activity for tumor growth and metastasis in relevant in vivo models is needed to establish NFIB as a therapeutic target. Here, using conditional gene knockout strategies in genetically engineered mouse models of SCLC, we found that upregulation of NFIB contributes to tumor progression, but NFIB is not required for metastasis. Molecular studies in NFIB wild-type and knockout tumors identified the pioneer transcription factors FOXA1/2 as candidate drivers of metastatic progression. Thus, while NFIB upregulation is a frequent event in SCLC during tumor progression, SCLC tumors can employ NFIB-independent mechanisms for metastasis, further highlighting the plasticity of these tumors., Significance: Small cell lung cancer cells overcome deficiency of the prometastatic oncogene NFIB to gain metastatic potential through various molecular mechanisms, which may represent targets to block progression of this fatal cancer type., (©2023 American Association for Cancer Research.)

Genomic rearrangements that give rise to oncogenic gene fusions can offer actionable targets for cancer therapy. Here we present a systematic analysis of oncogenic gene fusions among a clinically well-characterized, prospectively collected set of 278 primary colon cancers spanning diverse tumor stages and clinical outcomes. Gene fusions and somatic genetic variations were identified in fresh frozen clinical specimens by Illumina RNA-sequencing, the STAR fusion gene detection pipeline, and GATK RNA-seq variant calling. We considered gene fusions to be pathogenically relevant when recurrent, producing divergent gene expression (outlier analysis), or as functionally important (e.g., kinase fusions). Overall, 2.5% of all specimens were defined as harboring a relevant gene fusion (kinase fusions 1.8%). Novel configurations of BRAF, NTRK3, and RET gene fusions resulting from chromosomal translocations were identified. An R-spondin fusion was found in only one tumor (0.35%), much less than an earlier reported frequency of 10% in colorectal cancers. We also found a novel fusion involving USP9X-ERAS formed by chromothripsis and leading to high expression of ERAS, a constitutively active RAS protein normally expressed only in embryonic stem cells. This USP9X-ERAS fusion appeared highly oncogenic on the basis of its ability to activate AKT signaling. Oncogenic fusions were identified only in lymph node-negative tumors that lacked BRAF or KRAS mutations. In summary, we identified several novel oncogenic gene fusions in colorectal cancer that may drive malignant development and offer new targets for personalized therapy. [ABSTRACT FROM AUTHOR]

Cancer treatments composed of immune checkpoint inhibitors and oncogene-targeted drugs might improve cancer management, but there has been little investigation of their combined potential as yet. To estimate the fraction of cancer cases that might benefit from such combination therapy, we conducted an exploratory study of cancer genomic datasets to determine the proportion with somatic mutation profiles amenable to either immunotherapy or targeted therapy. We surveyed 13,349 genomic profiles from public databases for cases with specific mutations targeted by current agents or a burden of exome-wide nonsynonymous mutations (NsM) that exceed a proposed threshold for response to checkpoint inhibitors. Overall, 8.9% of cases displayed profiles that could benefit from combination therapy, which corresponded to approximately 11.2% of U.S. annual incident cancer cases. Frequently targetable mutations were in PIK3CA, BRAF, NF1, NRAS, and PTEN. We also noted a high burden of NsM in cases with targetable mutations in SMO, DDR2, FGFR1, PTCH1, FGFR2, and MET. Our results indicate that a significant proportion of solid tumor patients are eligible for immuno-targeted combination therapy, and they suggest prioritizing specific cancers for trials of certain targeted and checkpoint inhibitor drugs. [ABSTRACT FROM AUTHOR]

Oncogenic kinase fusions of ALK, ROS1, RET, and NTRK1 act as drivers in human lung and other cancers. Residual tumor burden following treatment of ALK or ROS1+ lung cancer patients with oncogene-targeted therapy ultimately enables the emergence of drug-resistant clones, limiting the long-term effectiveness of these therapies. To determine the signaling mechanisms underlying incomplete tumor cell killing in oncogene-addicted cancer cells, we investigated the role of EGFR signaling in drug-naïve cancer cells harboring these oncogene fusions. We defined three distinct roles for EGFR in the response to oncogene-specific therapies. First, EGF-mediated activation of EGFR blunted fusion kinase inhibitor binding and restored fusion kinase signaling complexes. Second, fusion kinase inhibition shifted adaptor protein binding from the fusion oncoprotein to EGFR. Third, EGFR enabled bypass signaling to critical downstream pathways such as MAPK. While evidence of EGFR-mediated bypass signaling has been reported after ALK and ROS1 blockade, our results extended this effect to RET and NTRK1 blockade and uncovered the other additional mechanisms in gene fusion-positive lung cancer cells, mouse models, and human clinical specimens before the onset of acquired drug resistance. Collectively, our findings show how EGFR signaling can provide a critical adaptive survival mechanism that allows cancer cells to evade oncogene-specific inhibitors, providing a rationale to cotarget EGFR to reduce the risks of developing drug resistance. [ABSTRACT FROM AUTHOR]

Oncogenic gene fusions drive many human cancers, but tools to more quickly unravel their functional contributions are needed. Here we describe methodology permitting fusion gene construction for functional evaluation. Using this strategy, we engineered the known fusion oncogenes, BCR-ABL1, EML4-ALK, and ETV6-NTRK3, as well as 20 previously uncharacterized fusion genes identified in The Cancer Genome Atlas datasets. In addition to confirming oncogenic activity of the known fusion oncogenes engineered by our construction strategy, we validated five novel fusion genes involving MET, NTRK2, and BRAF kinases that exhibited potent transforming activity and conferred sensitivity to FDA-approved kinase inhibitors. Our fusion construction strategy also enabled domain-function studies of BRAF fusion genes. Our results confirmed other reports that the transforming activity of BRAF fusions results from truncation-mediated loss of inhibitory domains within the N-terminus of the BRAF protein. BRAF mutations residing within this inhibitory region may provide a means for BRAF activation in cancer, therefore we leveraged the modular design of our fusion gene construction methodology to screen N-terminal domain mutations discovered in tumors that are wild-type at the BRAF mutation hotspot, V600. We identified an oncogenic mutation, F247L, whose expression robustly activated the MAPK pathway and sensitized cells to BRAF and MEK inhibitors. When applied broadly, these tools will facilitate rapid fusion gene construction for subsequent functional characterization and translation into personalized treatment strategies. [ABSTRACT FROM AUTHOR]

Autophagy activated after DNA damage or other stresses mitigates cellular damage by removing damaged proteins, lipids, and organelles. Activation of the master metabolic kinase AMPK enhances autophagy. Here we report that cyclin D1 restrains autophagy by modulating the activation of AMPK. In cell models of human breast cancer or in a cyclin D1-deficient model, we observed a cyclin D1-mediated reduction in AMPK activation. Mechanistic investigations showed that cyclin D1 inhibited mitochondrial function, promoted glycolysis, and reduced activation of AMPK (pT172), possibly through a mechanism that involves cyclin D1-Cdk4/Cdk6 phosphorylation of LKB1. Our findings suggest how AMPK activation by cyclin D1 may couple cell proliferation to energy homeostasis. [ABSTRACT FROM AUTHOR]

Significance: Comprehensive profiling of the enhancer landscape and 3D genome structure in liposarcoma identifies extensive enhancer-oncogene coamplification and enhancer hijacking events, deepening the understanding of how oncogenes are regulated in cancer., (©2023 The Authors; Published by the American Association for Cancer Research.)

Somatic mutations drive cancer development and are relevant to patient responses to treatment. Emerging evidence shows that variations in the somatic genome can be influenced by the germline genetic background. However, the mechanisms underlying these germline-somatic associations remain largely obscure. We hypothesized that germline variants can influence somatic mutations in a nearby cancer gene ("local impact") or a set of recurrently mutated cancer genes across the genome ("global impact") through their regulatory effect on gene expression. To test this hypothesis, tumor targeted sequencing data from 12,413 patients across 11 cancer types in the Dana-Farber Profile cohort were integrated with germline cancer gene expression quantitative trait loci (eQTL) from the Genotype-Tissue Expression Project. Variants that upregulate ATM expression were associated with a decreased risk of somatic ATM mutations across 8 cancer types. GLI2, WRN, and CBFB eQTL were associated with global tumor mutational burden of cancer genes in ovarian cancer, glioma, and esophagogastric carcinoma, respectively. An EPHA5 eQTL was associated with mutations in cancer genes specific to colorectal cancer, and eQTL related to expression of APC, WRN, GLI1, FANCA, and TP53 were associated with mutations in genes specific to endometrial cancer. These findings provide evidence that germline-somatic associations are mediated through expression of specific cancer genes, opening new avenues for research on the underlying biological processes., Significance: Analysis of associations between the germline genetic background and somatic mutations in patients with cancer suggests that germline variants can influence local and global tumor mutations by altering expression of cancer-related genes. See related commentary by Kar, p. 1165., (©2023 American Association for Cancer Research.)

Tumor suppressor TP53 is an important gene in human cancer because it is mutated in the majority of tumors, leading to loss-of-function or gain-of-function phenotypes. Mutated TP53 acts like an oncogene, driving cancer progression and causing poor patient outcomes. The role of mutated p53 in cancer has been known for over three decades, yet there is no FDA-approved drug to address the problem. This brief historical perspective highlights some of the insightful advances as well as challenges in therapeutic targeting of p53, especially the mutated forms. The article focuses on a functional p53 pathway restoration approach to drug discovery that years ago was not mainstream, encouraged by anyone, taught in textbooks, or embraced by medicinal chemists. With some knowledge, a clinician scientist's interest, and motivation, the author pursued a unique line of investigation leading to insights for functional bypass of TP53 mutations in human cancer. Like mutated Ras proteins, mutant p53 is fundamentally important as a therapeutic target in cancer and probably deserves a "p53 initiative" like the NCI's "Ras initiative." There is a link between naivete and enthusiasm for pursuing difficult problems, but important solutions are discovered through hard work and persistence. Hopefully, some benefit comes to patients with cancer from such drug discovery and development efforts., (©2023 The Authors; Published by the American Association for Cancer Research.)

Alternate RNA processing of caspase-9 generates the splice variants caspase 9a (C9a) and caspase 9b (C9b). C9b lacks a domain present in C9a, revealing a tumorigenic function that drives the phenotype of non--small cell lung cancer (NSCLC) cells. In this study, we elucidated the mechanistic underpinnings of the malignant character of this splice isoform. In NSCLC cells, C9b expression correlated with activation of the canonical arm of the NF-κB pathway, a major pathway linked to the NSCLC tumorigenesis. Mechanistic investigations revealed that C9b activates this pathway via direct interaction with cellular inhibitor of apoptosis 1 (cIAP1) and subsequent induction of the E3 ligase activity of this IAP family member. The C9b:cIAP1 interaction occurred via the BIR3 domain of cIAP1 and the IAP-binding motif of C9b, but did not require proteolytic cleavage of C9b. This protein:protein interaction was essential for C9b to promote viability and malignant growth of NSCLC cells in vitro and in vivo, broadly translating to diverse NSCLC oncogenotypes. Overall, our findings identified a novel point for therapeutic invention in NSCLC that may be tractable to small-molecule inhibitors, as a new point to broadly address this widespread deadly disease. [ABSTRACT FROM AUTHOR]

Evidence is accumulating that extracellular microvesicles (MV) facilitate progression and relapse in cancer. Using a model in which MVs derived from K562 chronic myelogenous leukemia (CML) cells transform normal hematopoietic transplants into leukemia-like cells, we defined the underlying mechanisms of this process through gene-expression studies and network analyses of transcription factors (TF) and miRNAs. We found that antitumor miRNAs were increased and several defense pathways were initiated during the early phases of oncogenic transformation. Later, oncomiRs and genes involved in cell cycle, DNA repair, and energy metabolism pathways were upregulated. Regulatory network analyses revealed that a number of TFs and miRNAs were responsible for the pathway dysregulation and the oncogenic transformation. In particular, we found that miR-146b-5p, which was highly expressed in MVs, coordinated the regulation of cancer-related genes to promote cell-transforming processes. Notably, treatment of recipient cells with MV derived from K562 cells expressing mimics of miR-146b-5p revealed that it accelerated the transformation process in large part by silencing the tumor-suppressor NUMB. High levels of miR-146b-5p also enhanced reactive oxygen species levels and genome instability of recipient cells. Taken together, our finding showed how upregulation of oncogenic miRNAs in MVs promote hematopoetic cells to a leukemic state, as well as a demonstration for TF and miRNA coregulatory analysis in exploring the dysregulation of cancers and discovering key factors. [ABSTRACT FROM AUTHOR]

Rab coupling protein (FIP1C), an effector of the Rab11 GTPases, including Rab25, is amplified and overexpressed in 10% to 25% of primary breast cancers and correlates with poor clinical outcome. Rab25 is also frequently silenced in triplenegative breast cancer, suggesting its ability to function as either an oncogene or a tumor suppressor, depending on the breast cancer subtype. However, the pathobiologic role of FIP family members, such as FIP1C, in a tumor-specific setting remains elusive. In this study, we used ErbB2 mouse models of human breast cancer to investigate FIP1C function in tumorigenesis. Doxycycline-induced expression of FIP1C in the MMTV-ErbB2 mouse model resulted in delayed mammary tumor progression. Conversely, targeted deletion of FIP1C in the mammary epithelium of an ErbB2 model coexpressing Cre recombinase led to accelerated tumor onset. Genetic and biochemical characterization of these FIP1C-proficient and -deficient tumor models revealed that FIP1C regulated E-cadherin (CDH1) trafficking and ZONAB (YBX3) function in Cdk4-mediated cell-cycle progression. Furthermore, we demonstrate that FIP1C promoted lysosomal degradation of ErbB2. Consistent with our findings in the mouse, the expression of FIP1C was inversely correlated with ErbB2 levels in breast cancer patients. Taken together, our findings indicate that FIP1C acts as a tumor suppressor in the context of ErbB2-positive breast cancer and may be therapeutically exploited as an alternative strategy for targeting aberrant ErbB2 expression. Cancer Res; 76(9); 2662-74. [ABSTRACT FROM AUTHOR]

EZH2 overexpression promotes cancer by increasing histone methylation to silence tumor suppressor genes, but how EZH2 levels become elevated in cancer is not understood. In this study, we investigated the mechanisms by which EZH2 expression is regulated in non-small cell lung carcinoma cells by oncogenic KRAS. In cells harboring KRASG12C and KRASG12D mutations, EZH2 expression was modulated by MEK-ERK and PI3K/AKT signaling, respectively. Accordingly, MEK-ERK depletion decreased EZH2 expression in cells harboring the KRASG12C mutation, whereas PI3K/AKT depletion decreased EZH2 expression, EZH2 phosphorylation, and STAT3 activity in KRASG12D-mutant cell lines. Combined inhibition of EZH2 and MEK-ERK or PI3K/AKT increased the sensitivity of cells with specific KRAS mutations to MEK-ERK and PI3K/AKT-targeted therapies. Our work defines EZH2 as a downstream effector of KRAS signaling and offers a rationale for combining EZH2 inhibitory strategies with MEK-ERK- or PI3K/AKT-targeted therapies to treat lung cancer patients, as stratified into distinct treatment groups based on specific KRAS mutations. [ABSTRACT FROM AUTHOR]

Alterations in EGFR, KRAS, and ALK are oncogenic drivers in lung cancer, but how oncogenic signaling influences immunity in the tumor microenvironment is just beginning to be understood. Immunosuppression likely contributes to lung cancer, because drugs that inhibit immune checkpoints like PD-1 and PD-L1 have clinical benefit. Here, we show that activation of the AKT-mTOR pathway tightly regulates PD-L1 expression in vitro and in vivo. Both oncogenic and IFNγ-mediated induction of PD-L1 was dependent on mTOR. In human lung adenocarcinomas and squamous cell carcinomas, membranous expression of PD-L1 was significantly associated with mTOR activation. These data suggest that oncogenic activation of the AKT-mTOR pathway promotes immune escape by driving expression of PD-L1, which was confirmed in syngeneic and genetically engineered mouse models of lung cancer where anmTOR inhibitor combined with a PD-1 antibody decreased tumor growth, increased tumor-infiltrating T cells, and decreased regulatory T cells. [ABSTRACT FROM AUTHOR]

Bladder cancer is a common and deadly malignancy but its treatment has advanced little due to poor understanding of the factors and pathways that promote disease. ATDC/TRIM29 is a highly expressed gene in several lethal tumor types, including bladder tumors, but its role as a pathogenic driver has not been established. Here we show that overexpression of ATDC in vivo is sufficient to drive both noninvasive and invasive bladder carcinoma development in transgenic mice. ATDC-driven bladder tumors were indistinguishable from human bladder cancers, which displayed similar gene expression signatures. Clinically, ATDC was highly expressed in bladder tumors in a manner associated with invasive growth behaviors. Mechanistically, ATDC exerted its oncogenic effects by suppressing miR- 29 and subsequent upregulation of DNMT3A, leading to DNA methylation and silencing of the tumor suppressor PTEN. Taken together, our findings established a role for ATDC as a robust pathogenic driver of bladder cancer development, identified downstream effector pathways, and implicated ATDC as a candidate biomarker and therapeutic target. [ABSTRACT FROM AUTHOR]

Driver mutations endow tumors with selective advantages and produce an array of pathogenic effects. Determining the function of somatic variants is important for understanding cancer biology and identifying optimal therapies. Here, we compiled a shared dataset from several cancer genomic databases. Two measures were applied to 535 cancer genes based on observed and expected frequencies of driver variants as derived from cancer-specific rates of somatic mutagenesis. The first measure comprised a binary classifier based on a binomial test; the second was tumor variant amplitude (TVA), a continuous measure representing the selective advantage of individual variants. TVA outperformed all other computational tools in terms of its correlation with experimentally derived functional scores of cancer mutations. TVA also highly correlated with drug response, overall survival, and other clinical implications in relevant cancer genes. This study demonstrates how a selective advantage measure based on a large cancer dataset significantly impacts our understanding of the spectral effect of driver variants in cancer. The impact of this information will increase as cancer treatment becomes more precise and personalized to tumor-specific mutations., Significance: A new selective advantage estimation assists in oncogenic driver identification and relative effect measurements, enabling better prognostication, therapy selection, and prioritization., (©2022 American Association for Cancer Research.)

Breast cancer is associated with alterations in a number of growth factor andhormone-regulated signalingpathways.Mousemodelsof metastatic breast cancer typically featuremutated oncoproteins that activate PI3K, Stat3, and Ras signaling, but the individual and combined roles of these pathways in breast cancer progression are poorly understood. In this study, we examined the relationship between oncogenic pathway activation and breast cancer subtype by analyzing mouse mammary tumor formation in which each pathway was activated singly or pairwise. All three oncogenes showed cooperation during primary tumor formation, but efficient dissemination was only dependent on Ras. In addition, transcriptional profiling demonstrated that Ras induced adenocarcinomas with molecular characteristics related to human basal-like and HER2+ tumors. Incontrast, Ras combinedwith PIK3CAH1047R, anoncogenic mutant linked to ER α+/luminal breast cancer in humans, induced metastatic luminal B-like tumors. Consistent with these data, elevated Ras signaling was associated with basal-like and HER 2+ subtype tumors in humans and showed a statistically significant negative association with estrogen receptor (ER) signaling across all breast cancer. Despite this, there are luminal tumors with elevated Ras signaling. Importantly, when considered as a continuous variable, Ras pathway activationwas strongly linked to reduced survival of patients with ERα+ disease independent of PI3K or Stat3 activation. Therefore, our studies suggest that Ras activation is a key determinant for dissemination and poor prognosis of ERα+/luminal breast cancer in humans, and hormone therapy supplemented with Ras-targeting agents may be beneficial for treating this aggressive subtype. [ABSTRACT FROM AUTHOR]

Recent advances in genome and transcriptome analysis have contributed to the identification of many potential cancer- related genes. Furthermore, biological and clinical investigations of the candidate genes provide us with a better understanding of carcinogenesis and development of cancer treatment. Here, we report a novel role of KIAA1324 as a tumor suppressor in gastric cancer. We observed that KIAA1324 was downregulated in most gastric cancers from transcriptome sequencing data and found that histone deacetylase was involved in the suppression of KIAA1324. Low KIAA1324 levels were associated with poor prognosis in gastric cancer patients. In the xenograft model, KIAA1324 significantly reduced tumor formation of gastric cancer cells and decreased development of preformed tumors. KIAA1324 also suppressed proliferation, invasion, and drug resistance and induced apoptosis in gastric cancer cells. Through protein interaction analysis, we identified GRP78 (glucose-regulated protein 78 kDa) as a KIAA1324- binding partner. KIAA1324 blocked oncogenic activities of GRP78 by inhibiting GRP78-caspase-7 interaction and suppressing GRP78-mediated AKT activation, thereby inducing apoptosis. In conclusion, our study reveals a tumor suppressive role of KIAA1324 via inhibition of GRP78 oncoprotein activities and provides new insight into the diagnosis and treatment of gastric cancer. [ABSTRACT FROM AUTHOR]

The Pim-1 kinase regulates cell survival, proliferation, and differentiation and is overexpressed frequently in many malignancies, including leukemia and skin cancer. In this study, we used kinase profiling analysis to demonstrate that 2'-hydroxycin-namicaldehyde (2'-HCA), a compound found in cinnamon, specifically inhibits Pim-1 activity. Cocrystallography studies determined the hydrogen bonding pattern between 2'-HCA and Pim-1. Notably, 2'-HCA binding altered the apo kinase structure in a manner that shielded the ligand from solvent, thereby acting as a gatekeeper loop. Biologically, 2'-HCA inhibited the growth of human erythroleukemia or squamous epidermoid carcinoma cells by inducing apoptosis. The compound was also effective as a chemopreventive agent against EGF-mediated neoplastic transformation. Finally, 2'-HCA potently suppressed the growth of mouse xenografts representing human leukemia or skin cancer. Overall, our results offered preclini cal proof of concept for 2'-HCA as a potent anticancer principle arising from direct targeting of the Pim-1 kinase. [ABSTRACT FROM AUTHOR]

This report delivers a comprehensive genetic alteration profile of lung adenocarcinomas (LADC) driven by ALK, RET, and ROS1 oncogene fusions. These tumors are difficult to study because of their rarity. Each drives only a low percentage of LADCs. Whole-exome sequencing and copy-number variation analyses were performed on a Japanese LADC cohort (n = 200) enriched in patients with fusions (n = 31, 15.5%), followed by deep resequencing for validation. The driver fusion cases showed a distinct profile with smaller numbers of nonsynonymous mutations in cancer-related genes or truncating mutations in SWI/SNF chromatin remodeling complex genes than in other LADCs (P < 0.0001). This lower mutation rate was independent of age, gender, smoking status, pathologic stage, and tumor differentiation (P < 0.0001) and was validated in nine fusion-positive cases from a U.S. LADCs cohort (n = 230). In conclusion, our findings indicate that LADCs with ALK, RET, and ROS1 fusions develop exclusively via their dependence on these oncogene fusions. The presence of such few alterations beyond the fusions supports the use of monotherapy with tyrosine kinase inhibitors targeting the fusion products in fusion-positive LADCs. [ABSTRACT FROM AUTHOR]

Assessing the functional significance of novel putative oncogenes remains a significant challenge given the limitations of current loss-of-function tools. Here, we describe a method that employs TALEN or CRISPR/Cas9-mediated knock-in of inducible degron tags (Degron-KI) that provides a versatile approach for the functional characterization of novel cancer genes and addresses many of the shortcomings of current tools. The Degron-KI system allows for highly specific, inducible, and allele-targeted inhibition of endogenous protein function, and the ability to titrate protein depletion with this system is able to better mimic pharmacologic inhibition compared with RNAi or genetic knockout approaches. The Degron-KI system was able to faithfully recapitulate the effects of pharmacologic EZH2 and PI3Ka inhibitors in cancer cell lines. The application of this system to the study of a poorly understood putative oncogene, SF3B1, provided the first causal link between SF3B1 hotspot mutations and splicing alterations. Surprisingly, we found that SF3B1-mutant cells are not dependent upon the mutated allele for in vitro growth, but instead depend upon the function of the remaining wild-type alleles. Collectively, these results demonstrate the broad utility of the Degron-KI system for the functional characterization of cancer genes. [ABSTRACT FROM AUTHOR]

Gastrointestinal stromal tumors (GIST) are the most common adult sarcomas and the oncogenic driver is usually a KIT or PDGFRA mutation. Although GISTs are often initially sensitive to imatinib or other tyrosine kinase inhibitors, resistance generally develops, necessitating backup strategies for therapy. In this study, we determined that a subset of human GIST specimens that acquired imatinib resistance acquired expression of activated forms of the MET oncogene. MET activation also developed after imatinib therapy in a mouse model of GIST (KitV558del/+ mice), where it was associated with increased tumor hypoxia. MET activation also occurred in imatinib-sensitive human GIST cell lines after imatinib treatment in vitro. MET inhibition by crizotinib or RNA interference was cytotoxic to an imatinib-resistant human GIST cell population. Moreover, combining crizotinib and imatinib was more effective than imatinib alone in imatinib-sensitive GIST models. Finally, cabozantinib, a dual MET and KIT small-molecule inhibitor, was markedly more effective than imatinib in multiple preclinical models of imatinib- sensitive and imatinib-resistant GIST. Collectively, our findings showed that activation of compensatory MET signaling by KIT inhibition may contribute to tumor resistance. Furthermore, our work offered a preclinical proof of concept for MET inhibition by cabozantinib as an effective strategy for GIST treatment. [ABSTRACT FROM AUTHOR]

Genetic alterations in the TGFβ signaling pathway in combination with oncogenic alterations lead to cancer development in the intestines. However, the mechanisms of TGFβ signaling suppression in malignant progression of intestinal tumors have not yet been fully understood. We have examined ApcΔ716 Tgfbr2ΔIEC compound mutant mice that carry mutations in Apc and Tgfbr2 genes in the intestinal epithelial cells. We found inflammatory microenvironment only in the invasive intestinal adenocarcinomas but not in noninvasive benign polyps of the same mice. We thus treated simple Tgfbr2ΔIEC mice with dextran sodium sulfate (DSS) that causes ulcerative colitis. Importantly, these Tgfbr2ΔIEC mice developed invasive colon cancer associated with chronic inflammation. We also found that TGFβ signaling is suppressed in human colitis-associated colon cancer cells. In the mouse invasive tumors, macrophages infiltrated and expressed MT1-MMP, causing MMP2 activation. These results suggest that inflammatory microenvironment contributes to submucosal invasion of TGFβ signaling-repressed epithelial cells through activation of MMP2. We further found that regeneration was impaired in Tgfbr2ΔIEC mice for intestinal mucosa damaged by DSS treatment or X-ray irradiation, resulting in the expansion of undifferentiated epithelial cell population. Moreover, organoids of intestinal epithelial cells cultured from irradiated Tgfbr2ΔIEC mice formed "long crypts" in Matrigel, suggesting acquisition of an invasive phenotype into the extracellular matrix. These results, taken together, indicate that a simple genetic alteration in the TGFβ signaling pathway in the inflamed and regenerating intestinal mucosa can cause invasive intestinal tumors. Such a mechanism may play a role in the colon carcinogenesis associated with inflammatory bowel disease in humans. [ABSTRACT FROM AUTHOR]

GOLPH3 is the first example of an oncogene that functions in secretory trafficking at the Golgi. The discovery of GOLPH30s roles in both cancer and Golgi trafficking raises questions about how GOLPH3 and the Golgi contribute to cancer. Our recent investigation of the regulation of GOLPH3 revealed a surprising response by the Golgi upon DNA damage that is mediated by DNA-PK and GOLPH3. These results provide new insight into the DNA damage response with important implications for understanding the cellular response to standard cancer therapeutic agents. [ABSTRACT FROM AUTHOR]

EGFR is the most common genetically altered oncogene in glioblastoma (GBM), but small-molecule EGFR tyrosine kinase inhibitors (TKI) have failed to yield durable clinical benefit. Here, we show that in two novel model systems of acquired resistance to EGFR TKIs, elevated expression of urokinase plasminogen activator (uPA) drives signaling through the MAPK pathway, which results in suppression of the proapoptotic BCL2-family member protein BIM (BCL2L11). In patient-derived GBM cells and genetic GBM models, uPA is shown to suppress BIM levels through ERK1/2 phosphorylation, which can be reversed by siRNA-mediated knockdown of uPA. TKI-resistant GBMs are resensitized to EGFR TKIs by pharmacologic inhibition of MEK or a BH3 mimetic drug to replace BIM function. A link between the uPA-uPAR-ERK1/2 pathway and BIM has not been previously demonstrated in GBM, and involvement of this signaling axis in resistance provides rationale for a new strategy to target EGFR TKI-resistant GBM. [ABSTRACT FROM AUTHOR]

Increased glucose utilization is a hallmark of human cancer that is used to image tumors clinically. In this widely used application, glucose uptake by tumors is monitored by positron emission tomography of the labeled glucose analogue 2[18F]fluoro-2-deoxy-D-glucose (FDG). Despite its widespread clinical use, the cellular and molecular mechanisms that determine FDG uptake--and that underlie the heterogeneity observed across cancers--remain poorly understood. In this study, we compared FDG uptake in mammary tumors driven by the Akt1, c-MYC, HER2/neu, Wnt1, or H-Ras oncogenes in genetically engineered mice, correlating it to tumor growth, cell proliferation, and expression levels of gene involved in key steps of glycolytic metabolism. We found that FDG uptake by tumors was dictated principally by the driver oncogene and was not independently associated with tumor growth or cellular proliferation. Oncogene downregulation resulted in a rapid decrease in FDG uptake, preceding effects on tumor regression, irrespective of the baseline level of uptake. FDG uptake correlated positively with expression of hexokinase-2 (HK2) and hypoxia-inducible factor-1α (HIF1α) and associated negatively with PFK-2b expression and p-AMPK. The correlation between HK2 and FDG uptake was independent of all variables tested, including the initiating oncogene, suggesting that HK2 is an independent predictor of FDG uptake. In contrast, expression of Glut1 was correlated with FDG uptake only in tumors driven by Akt or HER2/ neu. Together, these results demonstrate that the oncogenic pathway activated within a tumor is a primary determinant of its FDG uptake, mediated by key glycolytic enzymes, and provide a framework to interpret effects on this key parameter in clinical imaging. [ABSTRACT FROM AUTHOR]

BRAFV600E is a major oncogenic mutation found in approximately 50% of human melanoma that confers constitutive activation of the MAPK pathway and increased melanoma growth. Inhibition of BRAFV600E by oncogene targeting therapy increases overall survival of patients with melanoma, but is unable to produce many durable responses. Adaptive drug resistance remains the main limitation to BRAFV600E inhibitor clinical efficacy and immune-based strategies could be useful to overcome disease relapse. Tumor microenvironment greatly differs between visceral metastasis and primary cutaneous melanoma, and the mechanisms involved in the antimetastatic efficacy of BRAFV600E inhibitors remain to be determined. To address this question, we developed a metastatic BRAFV600E-mutant melanoma cell line and demonstrated that the antimetastatic properties of BRAF inhibitor PLX4720 (a research analogue of vemurafenib) require host natural killer (NK) cells and perforin. Indeed, PLX4720 not only directly limited BRAFV600E-induced tumor cell proliferation, but also affected NK cell functions. We showed that PLX4720 increases the phosphorylation of ERK1/2, CD69 expression, and proliferation of mouse NK cells in vitro. NK cell frequencies were significantly enhanced by PLX4720 specifically in the lungs of mice with BRAFV600E lung metastases. Furthermore, PLX4720 also increased human NK cell pERK1/2, CD69 expression, and IFNg release in the context of anti-NKp30 and IL2 stimulation. Overall, this study supports the idea that additional NK cell-based immunotherapy (by checkpoint blockade or agonists or cytokines) may combine well with BRAFV600E inhibitor therapy to promote more durable responses in melanoma. [ABSTRACT FROM AUTHOR]