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PDF file - 239KB, Western blot showed inhibition of autophagy in Atg5 and Atg7 knockdown cell lines.

Supplementary Tables 1 and 2 PDF file 91K, Table 1 contains clinical and genotypic data from the patient cohort referred to in Fig. 6. Table 2 contains shRNA target sequences

Supplementary Figure S3 PDF file 66K,Additional data related to the proliferative and apoptotic phenotypes of CRC cells expressing mutant Ras

PDF file - 162KB, PCR and western blot confirmed the genotype of mouse cell lines with different p53 status.

PDF file - 181KB, Deletion of Atg5 in pancreata disrupts beta-islets over time.

Supplementary Figure Legends PDF file 72K, Legends for Supplementary Figures 1-6

PDF file - 283KB, Western blot on tumor lines derived from primary tumors confirmed Atg5 status and also showed loss of p53.

PDF file - 18KB, Summary of genetic mutations in different human pancreatic tumor xenografts.

PDF file - 337KB, IHC staining shows absence of Atg5 expression and diminished autophagosomes in tumors with Atg5 deletion.

Supplementary Tables 1-2, Figures 1-8 from PTEN Is a Major Tumor Suppressor in Pancreatic Ductal Adenocarcinoma and Regulates an NF-κB–Cytokine Network

PDF file - 7894K, Supplementary Figure 7. Xenograft models of aggressive prostate cancer.

PDF file - 3402K, Supplementary Figure 6. Additional PTEN/AKT Pathway models.

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PDF file - 9226K, Supplementary Figure 1. Differentiating primary and metastatic lung lesions in GEM mouse models.

PDF file - 17933K, Supplementary Figure 4. Neuroendocrine carcinoma.

PDF file - 2509K, Supplementary Figure 3. Heterologous differentiation in prostate.

PDF file - 2674K, Supplementary Figure 2. Lung metastasis versus tumor embolism.

PDF file - 4441K, Supplementary Figure 5. PTEN/AKT Pathway models.

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Animal models, particularly mouse models, play a central role in the study of the etiology, prevention, and treatment of human prostate cancer. While tissue culture models are extremely useful in understanding the biology of prostate cancer, they cannot recapitulate the complex cellular interactions within the tumor microenvironment that play a key role in cancer initiation and progression. The National Cancer Institute (NCI) Mouse Models of Human Cancers Consortium convened a group of human and veterinary pathologists to review the current animal models of prostate cancer and make recommendations about the pathologic analysis of these models. More than 40 different models with 439 samples were reviewed, including genetically engineered mouse models, xenograft, rat, and canine models. Numerous relevant models have been developed over the past 15 years, and each approach has strengths and weaknesses. Analysis of multiple genetically engineered models has shown that reactive stroma formation is present in all the models developing invasive carcinomas. In addition, numerous models with multiple genetic alterations display aggressive phenotypes characterized by sarcomatoid carcinomas and metastases, which is presumably a histologic manifestation of epithelial–mesenchymal transition. The significant progress in development of improved models of prostate cancer has already accelerated our understanding of the complex biology of prostate cancer and promises to enhance development of new approaches to prevention, detection, and treatment of this common malignancy. Cancer Res; 73(9); 2718–36. ©2013 AACR.

Human colorectal cancer (CRC) is a major cause of cancer mortality and frequently harbors activating mutations in the KRAS gene. To understand the role of oncogenic KRAS in CRC, we engineered a mouse model of metastatic CRC that harbors an inducible oncogenic Kras allele (Krasmut) and conditional null alleles of Apc and Trp53 (iKAP). The iKAP model recapitulates tumor progression from adenoma through metastases. Whole-exome sequencing revealed that the Krasmut allele was heterogenous in primary tumors yet homogenous in metastases, a pattern consistent with activated Krasmut signaling being a driver of progression to metastasis. System-level and functional analyses revealed the TGF-β pathway as a key mediator of Krasmut-driven invasiveness. Genetic extinction of Krasmut resulted in specific elimination of the Krasmut subpopulation in primary and metastatic tumors, leading to apoptotic elimination of advanced invasive and metastatic disease. This faithful CRC model provides genetic evidence that Krasmut drives CRC invasion and maintenance of metastases.

Many common instigators drive the processes of inflammation and carcinogenesis. We have found such a common node in Yap1. In the context of cancer, YAP-TEAD complex is important in modulating the immune microenvironment, such that Yap 1-mediated transcriptional upregulation of CXCL5 by the prostate cancer cells in a PTEN/SMAD4 deficient mouse model leads to the recruitment of MDSCs through the interaction with CXCR2 on them. Depletion of MDSCs or pharmacologic inhibition of CXCR2 leads to impediment of cancer progression. In another well-established pancreatic cancer model (PDAC), Yap1/Tead2 governs escape from mutant Kras (G12D) inhibition through cooperative upregulation of E2F transcription factors to activate a cell cycle and DNA replication program. In the context of inflammation, specifically inflammatory bowel disease, telomere dysfunction is shown to activate pAtm/c-Abl-mediated phosphorylation and stabilization of Yap1 upregulating pro-IL-18, a major proinflammatory factor in IBD. This signaling axis cooperates with the gut microbiome stimulating cytosolic receptors causing activation of caspase-1 cleaving pro-IL-18 into mature IL-18. Epithelial IL-18 leads to recruitment of IFNγ-secreting T cells and other immunocytes provoking classical IBD pathology. Consistent with a role for DNA damage signaling driving IBD, newly diagnosed IBD patient samples exhibited elevated expression of pγH2AX, YAP1, Caspase-1, and IL-18 and significantly reduced telomere lengths. Telomerase reactivation in intestinal epithelium or pharmacologic inhibition of Atm, Yap1, or caspase-1 as well as antibiotic treatment of mice dramatically reduced IL-18 and inflammation. Thus, telomere dysfunction-induced activation of the Atm-Yap1-pro-IL-18 pathway identifies DNA damage signaling as a key instigator and promoter of IBD, illuminating novel therapeutic strategies. Citation Format: Guocan Wang, Xin Lu, Deepavali Chakravarti, Avnish Kapoor, Wantong Yao, Haoqiang Ying, Prasenjit Dey, Chiachin Wu, Denise Spring, Pingping Hou, Pingna Deng, Di Zhao, Baoli Hu, Mao Xizeng, Christopher Logothesis, Michael McArthur, Lynda Chin, Alan Wang, Sujun Hua, Hongai Xia, Gerald C Chu, Carol Lim, Eduardo Vilar, Sarah Blutt, Ronald A. DePinho. YAP in cancer and inflammation [abstract]. In: Proceedings of the AACR Special Conference on the Hippo Pathway: Signaling, Cancer, and Beyond; 2019 May 8-11; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(8_Suppl):Abstract nr IA24.

Pancreatic ductal adenocarcinoma is refractory to available therapies. We have previously shown that these tumors have elevated autophagy and that inhibition of autophagy leads to decreased tumor growth. Using an autochthonous model of pancreatic cancer driven by oncogenic Kras and the stochastic LOH of Trp53, we demonstrate that although genetic ablation of autophagy in the pancreas leads to increased tumor initiation, these premalignant lesions are impaired in their ability to progress to invasive cancer, leading to prolonged survival. In addition, mouse pancreatic cancer cell lines with differing p53 status are all sensitive to pharmacologic and genetic inhibition of autophagy. Finally, a mouse preclinical trial using cohorts of genetically characterized patient-derived xenografts treated with hydroxychloroquine showed responses across the collection of tumors. Together, our data support the critical role of autophagy in pancreatic cancer and show that inhibition of autophagy may have clinical utility in the treatment of these cancers, independent of p53 status. Significance: Recently, a mouse model with embryonic homozygous Trp53 deletion showed paradoxical effects of autophagy inhibition. We used a mouse model with Trp53 LOH (similar to human tumors), tumor cell lines, and patient-derived xenografts to show that p53 status does not affect response to autophagy inhibition. These findings have important implications on ongoing clinical trials. Cancer Discov; 4(8); 905–13. ©2014 AACR. See related commentary by Amaravadi and Debnath, p. 873 This article is highlighted in the In This Issue feature, p. 855

Activating mutations in KRAS are among the most frequent events in diverse human carcinomas and are particularly prominent in human pancreatic ductal adenocarcinoma (PDAC). An inducible Kras(G12D)-driven mouse model of PDAC has established a critical role for sustained Kras(G12D) expression in tumor maintenance, providing a model to determine the potential for and the underlying mechanisms of Kras(G12D)-independent PDAC recurrence. Here, we show that some tumors undergo spontaneous relapse and are devoid of Kras(G12D) expression and downstream canonical MAPK signaling and instead acquire amplification and overexpression of the transcriptional coactivator Yap1. Functional studies established the role of Yap1 and the transcriptional factor Tead2 in driving Kras(G12D)-independent tumor maintenance. The Yap1/Tead2 complex acts cooperatively with E2F transcription factors to activate a cell cycle and DNA replication program. Our studies, along with corroborating evidence from human PDAC models, portend a novel mechanism of escape from oncogenic Kras addiction in PDAC.

Here, Boutin et al. investigated the role of oncogenic KRAS in colorectal cancer (CRC). They generated a mouse model of metastatic CRC that harbors an inducible oncogenic Kras allele (Krasmut) and conditional null alleles of Apc and Trp53 (iKAP), which provides genetic evidence that Krasmut drives CRC invasion and maintenance of metastases.

Pancreatic ductal adenocarcinoma is a notoriously difficult-to-treat cancer and patients are in need of novel therapies. We have shown previously that these tumours have altered metabolic requirements, making them highly reliant on a number of adaptations including a non-canonical glutamine (Gln) metabolic pathway and that inhibition of downstream components of Gln metabolism leads to a decrease in tumour growth. Here we test whether recently developed inhibitors of glutaminase (GLS), which mediates an early step in Gln metabolism, represent a viable therapeutic strategy. We show that despite marked early effects on in vitro proliferation caused by GLS inhibition, pancreatic cancer cells have adaptive metabolic networks that sustain proliferation in vitro and in vivo. We use an integrated metabolomic and proteomic platform to understand this adaptive response and thereby design rational combinatorial approaches. We demonstrate that pancreatic cancer metabolism is adaptive and that targeting Gln metabolism in combination with these adaptive responses may yield clinical benefits for patients., Glutaminase inhibition (GLSi) has promising activity against certain cancers. Here, the authors show that GLSi has no effect on multiple mouse models of pancreatic cancer and characterize the metabolic pathways activated in response to GLSi whose concomitant inhibition may have therapeutic utility.

Initiation of pancreatic ductal adenocarcinoma (PDAC) is driven by oncogenic KRAS mutation, and disease progression is associated with frequent loss of tumor suppressors. In this study, human PDAC genome analyses revealed frequent deletion of the PTEN gene as well as loss of expression in primary tumor specimens. A potential role for PTEN as a haploinsufficient tumor suppressor is further supported by mouse genetic studies. The mouse PDAC driven by oncogenic Kras mutation and Pten deficiency also sustains spontaneous extinction of Ink4a expression and shows prometastatic capacity. Unbiased transcriptomic analyses established that combined oncogenic Kras and Pten loss promotes marked NF-κB activation and its cytokine network, with accompanying robust stromal activation and immune cell infiltration with known tumor-promoting properties. Thus, PTEN/phosphoinositide 3-kinase (PI3K) pathway alteration is a common event in PDAC development and functions in part to strongly activate the NF-κB network, which may serve to shape the PDAC tumor microenvironment. Significance: Detailed molecular genetics studies established that PTEN operates as a haploinsufficient tumor suppressor to promote metastatic PDAC development. The strong activation of the NF-κB–cytokine program in Pten-deficient tumors provides additional avenues for targeted therapies in tumors with altered PI3K regulation. Cancer Discovery; 1(2); 158–69. ©2011 AACR. Read the Commentary on this article by Chiao and Ling, p. 103 This article is highlighted in the In This Issue feature, p. 91

Effective clinical management of prostate cancer (PCA) has been challenged by significant intratumoural heterogeneity on the genomic and pathological levels and limited understanding of the genetic elements governing disease progression. Here, we exploited the experimental merits of the mouse to test the hypothesis that pathways constraining progression might be activated in indolent Pten-null mouse prostate tumours and that inactivation of such progression barriers in mice would engender a metastasis-prone condition. Comparative transcriptomic and canonical pathway analyses, followed by biochemical confirmation, of normal prostate epithelium versus poorly progressive Pten-null prostate cancers revealed robust activation of the TGFβ/BMP-SMAD4 signalling axis. The functional relevance of SMAD4 was further supported by emergence of invasive, metastatic and lethal prostate cancers with 100% penetrance upon genetic deletion of Smad4 in the Pten-null mouse prostate. Pathological and molecular analysis as well as transcriptomic knowledge-based pathway profiling of emerging tumours identified cell proliferation and invasion as two cardinal tumour biological features in the metastatic Smad4/Pten-null PCA model. Follow-on pathological and functional assessment confirmed cyclin D1 and SPP1 as key mediators of these biological processes, which together with PTEN and SMAD4, form a four-gene signature that is prognostic of prostate-specific antigen (PSA) biochemical recurrence and lethal metastasis in human PCA. This model-informed progression analysis, together with genetic, functional and translational studies, establishes SMAD4 as a key regulator of PCA progression in mice and humans.

The infant leukemia-associated gene Ott1 (Rbm15) has broad regulatory effects within murine hematopoiesis. However, germ line Ott1 deletion results in fetal demise prior to embryonic day 10.5, indicating additional developmental requirements for Ott1. The spen gene family, to which Ott1 belongs, has a transcriptional activation/repression domain and RNA recognition motifs and has a significant role in the development of the head and thorax in Drosophila melanogaster. Early Ott1-deficient embryos show growth retardation and incomplete closure of the notochord. Further analysis demonstrated placental defects in the spongiotrophoblast and syncytiotrophoblast layers, resulting in an arrest of vascular branching morphogenesis. The rescue of the placental defect using a conditional allele with a trophoblast-sparing cre transgene allowed embryos to form a normal placenta and survive gestation. This outcome showed that the process of vascular branching morphogenesis in Ott1-deficient animals was regulated by the trophoblast compartment rather than the fetal vasculature. Mice surviving to term manifested hyposplenia and abnormal cardiac development. Analysis of global gene expression of Ott1-deficient embryonic hearts showed an enrichment of hypoxia-related genes and a significant alteration of several candidate genes critical for cardiac development. Thus, Ott1-dependent pathways, in addition to being implicated in leukemogenesis, may also be important for the pathogenesis of placental insufficiency and cardiac malformations.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by the deregulation of the hedgehog signaling pathway. The Sonic Hedgehog ligand (Shh), absent in the normal pancreas, is highly expressed in pancreatic tumors and is sufficient to induce neoplastic precursor lesions in mouse models. We investigated the mechanism of Shh signaling in PDAC carcinogenesis by genetically ablating the canonical bottleneck of hedgehog signaling, the transmembrane protein Smoothened (Smo), in the pancreatic epithelium of PDAC-susceptible mice. We report that multistage development of PDAC tumors is not affected by the deletion of Smo in the pancreas, demonstrating that autocrine Shh–Ptch–Smo signaling is not required in pancreatic ductal cells for PDAC progression. However, the expression of Gli target genes is maintained in Smo-negative ducts, implicating alternative means of regulating Gli transcription in the neoplastic ductal epithelium. In PDAC tumor cells, we find that Gli transcription is decoupled from upstream Shh–Ptch–Smo signaling and is regulated by TGF-β and KRAS, and we show that Gli1 is required both for survival and for the KRAS-mediated transformed phenotype of cultured PDAC cancer cells.

Glioblastoma (GBM) is a highly lethal primary brain cancer with hallmark features of diffuse invasion, intense apoptosis resistance and florid necrosis, robust angiogenesis, and an immature profile with developmental plasticity. In the course of assessing the developmental consequences of central nervous system (CNS)-specific deletion of p53 and Pten, we observed a penetrant acute-onset malignant glioma phenotype with striking clinical, pathological, and molecular resemblance to primary GBM in humans. This primary, as opposed to secondary, GBM presentation in the mouse prompted genetic analysis of human primary GBM samples that revealed combined p53 and Pten mutations as the most common tumor suppressor defects in primary GBM. On the mechanistic level, the "multiforme" histopathological presentation and immature differentiation marker profile of the murine tumors motivated transcriptomic promoter-binding element and functional studies of neural stem cells (NSCs), which revealed that dual, but not singular, inactivation of p53 and Pten promotes cellular c-Myc activation. This increased c-Myc activity is associated not only with impaired differentiation, enhanced self-renewal capacity of NSCs, and tumor-initiating cells (TICs), but also with maintenance of TIC tumorigenic potential. Together, these murine studies have provided a highly faithful model of primary GBM, revealed a common tumor suppressor mutational pattern in human disease, and established c-Myc as a key component of p53 and Pten cooperative actions in the regulation of normal and malignant stem/progenitor cell differentiation, self-renewal, and tumorigenic potential.

SummaryActivated phosphoinositide 3-kinase (PI3K)-AKT signaling appears to be an obligate event in the development of cancer. The highly related members of the mammalian FoxO transcription factor family, FoxO1, FoxO3, and FoxO4, represent one of several effector arms of PI3K-AKT signaling, prompting genetic analysis of the role of FoxOs in the neoplastic phenotypes linked to PI3K-AKT activation. While germline or somatic deletion of up to five FoxO alleles produced remarkably modest neoplastic phenotypes, broad somatic deletion of all FoxOs engendered a progressive cancer-prone condition characterized by thymic lymphomas and hemangiomas, demonstrating that the mammalian FoxOs are indeed bona fide tumor suppressors. Transcriptome and promoter analyses of differentially affected endothelium identified direct FoxO targets and revealed that FoxO regulation of these targets in vivo is highly context-specific, even in the same cell type. Functional studies validated Sprouty2 and PBX1, among others, as FoxO-regulated mediators of endothelial cell morphogenesis and vascular homeostasis.

The genetic paradigm of cancer, focused largely on sequential molecular aberrations and associated biological impact in the neoplastic cell compartment of malignant tumors, has dominated our view of cancer pathogenesis. For the most part, this conceptualization has overlooked the dynamic and complex contributions of the surrounding microenvironment comprised of non-tumor cells (stroma) that may resist, react to, and/or foster tumor development. Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease in which a prominent tumor stroma compartment is a defining characteristic. Indeed, the bulk of PDAC tumor volume consists of non-neoplastic fibroblastic, vascular, and inflammatory cells surrounded by immense quantities of extracellular matrix, far exceeding that found in most other tumor types. Remarkably, little is known about the composition and physiology of the PDAC tumor microenvironment, in particular, the role of stroma in tumor initiation and progression. This review attempts to define key challenges, opportunities and state-of-knowledge relating to the PDAC microenvironment research with an emphasis on how inflammatory processes and key cancer pathways may shape the ontogeny of the tumor stroma. Such knowledge may be used to understand the evolution and biology of this lethal cancer and may convert these insights into new points of therapeutic intervention.

Activating KRAS mutations and p16 Ink4a inactivation are near universal events in human pancreatic ductal adenocarcinoma (PDAC). In mouse models, Kras G12D initiates formation of premalignant pancreatic ductal lesions, and loss of either Ink4a / Arf ( p16 Ink4a / p19 Arf ) or p53 enables their malignant progression. As recent mouse modeling studies have suggested a less prominent role for p16 Ink4a in constraining malignant progression, we sought to assess the pathological and genomic impact of inactivation of p16 Ink4a , p19 Arf , and/or p53 in the Kras G12D model. Rapidly progressive PDAC was observed in the setting of homozygous deletion of either p53 or p16 Ink4a , the latter with intact germ-line p53 and p19 Arf sequences. Additionally, Kras G12D in the context of heterozygosity either for p53 plus p16 Ink4a or for p16 Ink4a / p19 Arf produced PDAC with longer latency and greater propensity for distant metastases relative to mice with homozygous deletion of p53 or p16 Ink4a / p19 Arf . Tumors from the double-heterozygous cohorts showed frequent p16 Ink4a inactivation and loss of either p53 or p19 Arf . Different genotypes were associated with specific histopathologic characteristics, most notably a trend toward less differentiated features in the homozygous p16 Ink4a / p19 Arf mutant model. High-resolution genomic analysis revealed that the tumor suppressor genotype influenced the specific genomic patterns of these tumors and showed overlap in regional chromosomal alterations between murine and human PDAC. Collectively, our results establish that disruptions of p16 Ink4a and the p19 ARF -p53 circuit play critical and cooperative roles in PDAC progression, with specific tumor suppressor genotypes provocatively influencing the tumor biological phenotypes and genomic profiles of the resultant tumors.

Genetic and biochemical data have identified Smad4 as a key intracellular effector of the transforming growth factor beta (TGFbeta superfamily of secreted ligands. In mouse, Smad4-null embryos do not gastrulate, a phenotype consistent with loss of other TGFbeta-related signaling components. Chimeric analysis reveals a primary requirement for Smad4 in the extra-embryonic lineages; however, within the embryo proper, characterization of the specific roles of Smad4 during gastrulation and lineage specification remains limited. We have employed a Smad4 conditional allele to specifically inactivate the Smad4 gene in the early mouse epiblast. Loss of Smad4 in this tissue results in a profound failure to pattern derivatives of the anterior primitive streak, such as prechordal plate, node, notochord and definitive endoderm. In contrast to these focal defects, many well-characterized TGFbeta- and Bmp-regulated processes involved in mesoderm formation and patterning are surprisingly unaffected. Mutant embryos form abundant extra-embryonic mesoderm, including allantois, a rudimentary heart and middle primitive streak derivatives such as somites and lateral plate mesoderm. Thus, loss of Smad4 in the epiblast results not in global developmental abnormalities but instead in restricted patterning defects. These results suggest that Smad4 potentiates a subset of TGFbeta-related signals during early embryonic development, but is dispensable for others.

Uniquely amongst the major tumor types, the premalignant state in colorectal cancer (CRC) is readily detectable and diagnosed. Indeed, a multi-step process of CRC genesis was defined by the seminal work of Vogelstein et al, who described the mutational events leading from adenoma to adenocarcinoma. In addition to genetic aberrations, recent evidence has highlighted the importance of the gut microbiome and associated inflammation in predicting CRC progression. To date however, these insights have not led to significant changes in the treatment paradigm because efforts continue to be focused on the later stages of disease. We believe CRC presents an exceptional opportunity for disease interception but to design effective interventional strategies, the exact sequence of molecular events underlying progression needs to be better defined and understood. To address these needs, we have assembled a clinically annotated sample database encompassing all stages of CRC (healthy colon, adjacent mucosa, adenomas, high-grade dysplasia, primary CRC and liver metastases), including samples from the conventional, microsatellite stable subtype, as well as from the serrated, microsatellite instable pathway. The progression status of each sample was characterized using standard pathology criteria. In addition, molecular progression was determined by targeted mutation profiling and targeted copy number profiling, as well as genome-wide expression profiling. This analysis confirms previous observations of early mutational events at the adenoma stage, including known tumor suppressor and oncogene driver mutations, e.g. KRAS G12 and G13 are mutated in 15% of the conventional adenomas but not in sessile serrated adenomas, as well as in 23% of the colorectal tumors. Copy number aberrations were observed at the adenoma and carcinoma stage, but with a lower prevalence then somatic mutations. Furthermore, genome wide expression analysis indicates that several pathways known to be affected in colorectal cancer are already disregulated at the adenoma stage. These pathways include Wnt signaling, mucosal barrier defects, bile acid metabolism, and several immune respons genes, again fingerpointing at the interplay between local inflammation, the microbiome, and epithelial events. In addition, we observed that while genetic events are very dissimilar between the serrated/MSI and conventional/MSS pathway, the transcriptional regulation has many similarities, indicating at a possibility at targeting these disease subtypes using the same therapeutics. These initial findings provide rational avenues to intercept CRC at the adenoma stage and efforts are now focused on exploring the added role of the colonic microbiota and immune system modulation. A more comprehensive and integrated view of the changes associated with disease initiation will lead to the identification of new paths for prevention, interception and cure. Citation Format: Joke Reumers, Liesbeth Van Wesenbeeck, Eric Ciamporcero, Gerald Chu, Stan Gaj, Emanuele Palescandolo, Carl Van Hove, Karin Verstraeten, Gary Borzillo, Dianna Wu, Pieter Peeters, Janine Arts. Characterisation of molecular events across the colorectal cancer progression axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4388. doi:10.1158/1538-7445.AM2017-4388

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive disease with poor prognosis. Therefore, novel treatment options are essential to combat this highly refractory disease. Oncogenic Kras can promote a metabolic rewiring of pancreatic cancers, including the non-canonical use of glutamine to support growth and proliferation through redox homeostasis. Indeed, inhibition of downstream components of glutamine metabolism leads to a decrease in tumor growth. The first step in glutamine metabolism is mediated by the enzyme glutaminase (GLS) which catalyzes the conversion of glutamine to glutamate in the mitochondria where, in PDAC, glutamine-derived glutamate is metabolized ultimately resulting in increased reducing potential in the form of increased NADPH and GSH. An outstanding question in pancreatic cancer is whether GLS inhibition is a viable therapeutic strategy given it is the most proximal enzyme in the PDAC-specific glutamine metabolism pathway, and how this may differ from targeting distal parts of the pathway. Using a combination of in vitro and in vivo models of pancreatic cancer, we tested whether recently developed highly potent inhibitors of GLS are an effective therapy for PDAC. We demonstrate that despite dramatic early effects on in vitro proliferation caused by GLS inhibition, pancreatic cancer cells have adaptive metabolic networks that allow them to sustain proliferation in vitro and in vivo. Through an integrated proteomic and metabolomic analysis, we identify multiple compensatory pathways that may explain the resistance to GLS inhibition and show as proof of concept that combining inhibitors to these pathways with GLS inhibitors may have therapeutic utility. Citation Format: Joseph D. Mancias, Douglas E. Biancur, Joao A. Paulo, Maria Quiles Del Rey, Cristovão M. Sousa, Xiaoxu Wang, Gerald C. Chu, Steven P. Gygi, J. Wade Harper, Alec C. Kimmelman. Pancreatic cancers develop metabolic resistance pathways to glutaminase inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4986. doi:10.1158/1538-7445.AM2017-4986

OFD syndrome is a group of at least nine disorders that overlap substantially in their physical abnormalities. Although many different malformations are seen in this syndrome, consistent findings include oral anomalies, particularly cleft lip or palate or both, facial anomalies, such as hypertelorism, micrognathia, frontal bossing, or facial asymmetry, and digital anomalies. Other frequent anomalies include central nervous system and genitourinary tract abnormalities. 1,2 Mental retardation is also commonly found in OFD syndrome, type I. 3 We present a case of OFD syndrome, type I, diagnosed in a second trimester fetus.

Animal models, particularly mouse models, play a central role in the study of the etiology, prevention, and treatment of human prostate cancer. While tissue culture models are extremely useful in understanding the biology of prostate cancer, they cannot recapitulate the complex cellular interactions within the tumor microenvironment that play a key role in cancer initiation and progression. The National Cancer Institute (NCI) Mouse Models of Human Cancers Consortium convened a group of human and veterinary pathologists to review the current animal models of prostate cancer and make recommendations about the pathologic analysis of these models. More than 40 different models with 439 samples were reviewed, including genetically engineered mouse models, xenograft, rat, and canine models. Numerous relevant models have been developed over the past 15 years, and each approach has strengths and weaknesses. Analysis of multiple genetically engineered models has shown that reactive stroma formation is present in all the models developing invasive carcinomas. In addition, numerous models with multiple genetic alterations display aggressive phenotypes characterized by sarcomatoid carcinomas and metastases, which is presumably a histologic manifestation of epithelial–mesenchymal transition. The significant progress in development of improved models of prostate cancer has already accelerated our understanding of the complex biology of prostate cancer and promises to enhance development of new approaches to prevention, detection, and treatment of this common malignancy. Cancer Res; 73(9); 2718–36. ©2013 AACR.

N-RAS is one member of a family of oncoproteins that are commonly mutated in cancer. Activating mutations in NRAS occur in a subset of colorectal cancers, but little is known about how the mutant protein contributes to the onset and progression of the disease. Using genetically engineered mice, we find that mutant N-RAS strongly promotes tumorigenesis in the context of inflammation. The protumorigenic nature of mutant N-RAS is related to its antiapoptotic function, which is mediated by activation of a noncanonical mitogen-activated protein kinase pathway that signals through STAT3. As a result, inhibition of MAP–ERK kinase selectively induces apoptosis in autochthonous colonic tumors expressing mutant N-RAS. The translational significance of this finding is highlighted by our observation that NRAS mutation correlates with a less favorable clinical outcome for patients with colorectal cancer. These data show for the first time the important role that N-RAS plays in colorectal cancer. Significance: Little is known about N-RAS function in normal biology or in cancer. Our study links the antiapoptotic function of mutant N-RAS to its ability to promote colorectal cancer in an inflammatory context. In addition, our study pinpoints a therapeutic strategy for this distinct colorectal cancer subtype. Cancer Discov; 3(3); 294–307. ©2013 AACR. This article is highlighted in the In This Issue feature, p. 239

During the development of the mammalian neuromuscular junction, acetylcholine receptors (AChRs) become localized to the postsynaptic muscle membrane. As this process nears completion, the fetal form of the receptor, containing a gamma subunit (composition alpha 2 beta gamma delta) is gradually replaced by an epsilon subunit-containing adult form (alpha 2 beta epsilon delta). To understand how this transition is controlled, we compared the expression and regulation of the AChR gamma and epsilon subunits in developing, adult, and cultured muscles. Immunostaining with subunit-specific antibodies showed that replacement of gamma subunit- by epsilon subunit-containing AChRs occurs largely during the first postnatal week in fast-twitch muscles, and occurs homogeneously throughout individual endplates. In the slow-twitch soleus, however, this transition is delayed, and in the multiply innervated slow fibers of extraocular muscle, gamma subunit expression persists into adulthood. The transcriptional bases of the AChR subunit transition, and of these intermuscular variations, were demonstrated in mice bearing transgenes containing promoter elements from the AChR gamma and epsilon subunit genes, each coupled to a nuclear-localized beta-galactosidase (nlacZ) reporter. We show that transgene expression is stimulated by the nerve-derived inducer of AChR expression, ARIA, in myotubes cultured from gamma-nlacZ as well as epsilon-nlacZ mice. However, the expression of gamma-nlacZ, but not epsilon-nlacZ, is increased by treatment of myotubes with TTX, and the ARIA sensitivity of gamma-nlacZ is dependent on the electrical state of the myotube. Thus, the promoters of the gamma and epsilon subunit genes may integrate ARIA- and activity-dependent signals in different ways to generate their complementary patterns of expression.

Developing motor axons induce synaptic specializations in muscle fibers, including preferential transcription of acetylcholine receptor (AChR) subunit genes by subsynaptic nuclei. One candidate nerve-derived signaling molecule is AChR-inducing activity (ARIA)/heregulin, a ligand of the erbB family of receptor tyrosine kinases. Here, we asked whether ARIA and erbB kinases are expressed in patterns compatible with their proposed signaling roles. In developing muscle, ARIA was present not only at synaptic sites, but also in extrasynaptic regions of the muscle fiber. ARIA was synthesized, rather than merely taken up, by muscle cells, as indicated by the presence of ARIA mRNA in muscle and of ARIA protein in a clonal muscle cell line. ARIA-responsive myotubes expressed both erbB2 and erbB3, but little EGFR/erbB1 or erbB4. In adults, erbB2 and erbB3 were localized to the postsynaptic membrane. ErbB3 was restricted to the postsynaptic membrane perinatally, at a time when ARIA was still broadly distributed. Thus, our data are consistent with a model in which ARIA interacts with erbB kinases on the muscle cell surface to provide a local signal that induces synaptic expression of AChR genes. However, much of the ARIA is produced by muscle, not nerve, and the spatially restricted response may result from the localization of erbB kinases as well as of ARIA. Finally, we show that erbB3 is not concentrated at synaptic sites in mutant mice that lack rapsyn, a cytoskeletal protein required for AChR clustering, suggesting that pathways for synaptic AChR expression and clustering interact.

Inductive interactions between motor neuron and muscle result in the formation of synaptic structures at the neuromuscular junction. The localized appearance of synaptic proteins is due in part to the selective expression of specific genes in the muscle nuclei which lie beneath the motor endplate. For example, synapse-specific expression of the acetylcholine receptor subunit genes contributes to the restricted distribution of the acetylcholine receptor. A transynaptic, motor neuron-derived signal is thought to induce changes in the transcriptional potential of synaptic nuclei. Although the precise mechanisms of gene activation have yet to be elucidated, a neuronally derived factor called ARIA is likely to play a central role in this process.

The discovery of potent inhibitors of the BRAF proto-oncogene has revolutionized therapy for melanoma harboring mutations in BRAF, yet NRAS-mutant melanoma remains without an effective therapy. Because direct pharmacological inhibition of the RAS proto-oncogene has thus far been unsuccessful, we explored systems biology approaches to identify synergistic drug combination(s) that can mimic RAS inhibition. Here, leveraging an inducible mouse model of NRAS-mutant melanoma, we show that pharmacological inhibition of mitogen-activated protein kinase kinase (MEK) activates apoptosis but not cell-cycle arrest, which is in contrast to complete genetic neuroblastoma RAS homolog (NRAS) extinction, which triggers both of these effects. Network modeling pinpointed cyclin-dependent kinase 4 (CDK4) as a key driver of this differential phenotype. Accordingly, combined pharmacological inhibition of MEK and CDK4 in vivo led to substantial synergy in therapeutic efficacy. We suggest a gradient model of oncogenic NRAS signaling in which the output is gated, resulting in the decoupling of discrete downstream biological phenotypes as a result of incomplete inhibition. Such a gated signaling model offers a new framework to identify nonobvious coextinction target(s) for combined pharmacological inhibition in NRAS-mutant melanomas.

Tumor maintenance relies on continued activity of driver oncogenes, although their rate-limiting role is highly context-dependent. Oncogenic Kras mutation is the signature event in pancreatic ductal adenocarcinoma (PDAC), serving a critical role in tumor initiation. Here, an inducible KrasG12D-driven PDAC mouse model establishes that advanced PDAC remain strictly dependent on KrasG12D expression. Transcriptome and metabolomic analysis indicate that KrasG12D serves a vital role in controlling tumor metabolism through stimulation of glucose uptake and channeling of glucose intermediates into the hexosamine biosynthesis and pentose phosphate pathways (PPP). These studies also reveal that oncogenic Kras promotes ribose biogenesis. Unlike canonical models, we demonstrate that KrasG12D drives glycolysis intermediates into the non-oxidative PPP, thereby decoupling ribose biogenesis from NADP/NADPH-mediated redox control. Together, this work provides in vivo mechanistic insights into how oncogenic Kras promotes metabolic reprogramming in native tumors and illuminates potential metabolic targets that can be exploited for therapeutic benefit in PDAC. Citation Format: Haoqiang Ying, Hailei Zhang, Jonathan L. Coloff, Haiyan Yan, Wei Wang, Shujuan Chen, Andrea Viale, Hongwu Zheng, Ji-hye Paik, Carol Lim, Alexander R. Guimaraes, Alec C. Kimmelman, Eric S. Martin, Jeffery Chang, Aram Hezel, Samuel R. Perry, Jian Hu, Boyi Gan, Yonghong Xiao, John M. Asara, Ralph Weissleder, Y. Alan Wang, Costas A. Lyssiotis, Lynda Chin, Lewis C. Cantley, Ronald A. DePinho, Sujun Hua, Gerald C. Chu, Eliot Fletcher-Sananikone, Jason W. Locasale, Jaekyoung Son. Oncogenic Kras maintains pancreatic tumors through regulation of anabolic glucose metabolism. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Progress and Challenges; Jun 18-21, 2012; Lake Tahoe, NV. Philadelphia (PA): AACR; Cancer Res 2012;72(12 Suppl):Abstract nr A101.

To characterize somatic alterations in colorectal carcinoma, we conducted a genome-scale analysis of 276 samples, analysing exome sequence, DNA copy number, promoter methylation and messenger RNA and microRNA expression. A subset of these samples (97) underwent low-depth-of-coverage whole-genome sequencing. In total, 16% of colorectal carcinomas were found to be hypermutated: three-quarters of these had the expected high microsatellite instability, usually with hypermethylation and MLH1 silencing, and one-quarter had somatic mismatch-repair gene and polymerase ε (POLE) mutations. Excluding the hypermutated cancers, colon and rectum cancers were found to have considerably similar patterns of genomic alteration. Twenty-four genes were significantly mutated, and in addition to the expected APC, TP53, SMAD4, PIK3CA and KRAS mutations, we found frequent mutations in ARID1A, SOX9 and FAM123B. Recurrent copy-number alterations include potentially drug-targetable amplifications of ERBB2 and newly discovered amplification of IGF2. Recurrent chromosomal translocations include the fusion of NAV2 and WNT pathway member TCF7L1. Integrative analyses suggest new markers for aggressive colorectal carcinoma and an important role for MYC-directed transcriptional activation and repression., National Institutes of Health (U.S.) (Grant U24CA143799), National Institutes of Health (U.S.) (Grant U24CA143835), National Institutes of Health (U.S.) (Grant U24CA143840), National Institutes of Health (U.S.) (Grant U24CA143843), National Institutes of Health (U.S.) (Grant U24CA143845), National Institutes of Health (U.S.) (Grant U24CA143848), National Institutes of Health (U.S.) (Grant U24CA143858), National Institutes of Health (U.S.) (Grant U24CA143866), National Institutes of Health (U.S.) (Grant U24CA143867), National Institutes of Health (U.S.) (Grant U24CA143882), National Institutes of Health (U.S.) (Grant U24CA143883), National Institutes of Health (U.S.) (Grant U24CA144025), National Institutes of Health (U.S.) (Grant U54HG003067), National Institutes of Health (U.S.) (Grant U54HG003079), National Institutes of Health (U.S.) (Grant U54HG003273)

Preclinical trials in mice represent a critical step in the evaluation of experimental therapeutics. Genetically engineered mouse models (GEMMs) represent a promising platform for the evaluation of drugs, particularly those targeting the tumor microenvironment. We evaluated sunitinib, an angiogenesis inhibitor that targets VEGF and PDGF receptor signaling, in two GEMMs of pancreatic cancer. Sunitinib did not reduce tumor burden in pancreatic ductal adenocarcinoma (PDAC), whereas tumor burden was reduced in the pancreatic neuroendocrine tumor (PNET) model, the latter results confirming and extending previous studies. To explore the basis for the lack of pathologic response in PDAC, we used noninvasive microbubble contrast-enhanced ultrasound imaging, which revealed that sunitinib reduced blood flow both in PDAC and in PNET, concomitant with a reduction in vessel density; nevertheless, PDAC tumors continued to grow, whereas PNET were growth impaired. These results parallel the response in humans, where sunitinib recently garnered FDA and European approval in PNET, whereas two antiangiogenic drugs failed to demonstrate efficacy in PDAC clinical trials. The demonstration of on-target activity but with discordant benefit in the PDAC and PNET GEMMs illustrates the potential value of linked preclinical and clinical trials.