bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B01: A portable imaging system for fluorescence-guided surgery on a human colon cancer patient-derived orthotopic xenograft (PDOX™) nude mouse model
Authors: Hiroshima Yukihiko , Maawy Ali , Kaushal Sharmeela , Zhang Yong , Uehara Fuminari , Miwa Shinji , Yano Shuya , Sato Sho , Murakami Takashi , Momiyama Masashi , Chishima Takashi , Tanaka Kuniya , Bouvet Michael , Endo Itaru , Hoffman Robert M.
Published: May 2015

In this study, we determined the effectiveness of fluorescence-guided surgery (FGS) using a fluorophore-conjugated anti-carcinoembryonic antigen (CEA) antibody on a colon-cancer patient-derived orthotopic xenografts (PDOX™) nude mouse model. The patient tumor was established in NOD/SCID mice and passed orthotopically in nude mice to make PDOX™ models. Eight weeks after orthotopic implantation in nude mice, a monoclonal anti-CEA antibody conjugated with Alexa 488 was delivered to the PDOX™ models as a single intravenous dose 24 hours before laparotomy. The tumor was completely resected under fluorescence guidance using a hand-held portable fluorescence imaging system. Frozen section microscopy of the resected specimen demonstrated that the anti-CEA antibody selectively labeled cancer cells in the colon cancer PDOX™. Histologic evaluation of the resected specimen demonstrated that cancer cells were not present in the margins. The results of the present report predict that FGS using a fluorophore-conjugated anti-CEA antibody and hand-held portable imaging system should improve intraoperative staging and efficacy of resection for colorectal cancer in the clinic.

Citation Format: Yukihiko Hiroshima, Ali Maawy, Sharmeela Kaushal, Yong Zhang, Fuminari Uehara, Shinji Miwa, Shuya Yano, Sho Sato, Takashi Murakami, Masashi Momiyama, Takashi Chishima, Kuniya Tanaka, Michael Bouvet, Itaru Endo, Robert M. Hoffman. A portable imaging system for fluorescence-guided surgery on a human colon cancer patient-derived orthotopic xenograft (PDOX™) nude mouse model. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B01.
Abstract B02: Modeling of early to invasive stages of pancreatic cancer progression with an iPSC-like line from human pancreatic ductal adenocarcinoma
Authors: Kim Jungsun , Hoffman John P. , Reichert Maximilian , Rhim Andrew , Stanger Ben Z. , Gumbs Andrew , Zaret Kenneth S.
Published: May 2015

Pancreatic ductal adenocarcinoma (PDAC) has one of the worst prognoses of any human malignancy. When human PDAC cells are injected into immunodeficient animals, they create tumors of the late stage from which they were derived. We hypothesized that if human PDAC cells were converted to pluripotency and then allowed to differentiate back into pancreatic tissue, they might undergo early stages of cancer. Although most induced pluripotent stem cell (iPSC) lines were not of the expected cancer genotype, one PDAC line, 10–22 cells, when injected into immunodeficient mice, generates pancreatic intraepithelial neoplasia (PanIN) precursors to PDAC that progress to the invasive stage. The PanIN-like cells secrete or release proteins from many genes that are known to be expressed in human pancreatic cancer progression and that predicted an HNF4a network in intermediate-stage lesions. Recent studies show that the PanIN cells progress to metastases at longer time. The cells are being engineered so that tumor progression, and regression in response to drugs, can be monitored in vivo. Thus, rare events allow iPSC technology to provide a live human cell model of early pancreatic cancer and insights into disease progression.

Citation Format: Jungsun Kim, John P. Hoffman, Maximilian Reichert, Andrew Rhim, Ben Z. Stanger, Andrew Gumbs, Kenneth S. Zaret. Modeling of early to invasive stages of pancreatic cancer progression with an iPSC-like line from human pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B02.
Abstract B09: Aspirin inhibits cyclooxygenase 2-mediated prostaglandin production and tumorigenesisin a preclinical model of tuberous sclerosis complex
Authors: Li Chenggang , Lee Po-Shun , Sun Yang , Gu Xiaoxiao , Zhang Erik , Wu Chin-Lee , Parkhitko Andrey , Aurrichio Neil , Morrison Tasha , Blenis John , Xu Kai-Feng , Henske Elizabeth Petri , Levy Bruce , Kwiatkowski David , Yu Jane
Published: May 2015

Lymphangioleiomyomatosis (LAM) is a female predominant progressive and neoplastic disorder that leads to lung destruction and respiratory failure primarily in women. LAM is typically due to TSC2 mutations resulting in mTORC1 activation in proliferative smooth muscle-like cells in the lung. The female predominance of LAM suggests that estradiol contributes to disease development.

Metabolomic profiling identified estradiol-enhanced prostaglandin biosynthesis signature in Tsc2-deficient cells, both in vitro and in vivo. Estradiol increased the expression of cyclooxygenase-2 (COX-2), a rate-limiting enzyme in prostaglandin biosynthesis, which was increased at baseline in TSC2-deficient cells, and was not affected by rapamycin treatment, but decreased by Torin 1 treatment and Rictor knockdown, associated with reduction of levels phospho-Akt (S473). Prostaglandin production was also increased in TSC2-deficient cells. In preclinical models, Celecoxib or aspirin treatment suppressed tumor progression. LAM patients had significantly higher serum prostaglandin levels than healthy women. 15-epi-lipoxin-A4 was identified in exhaled breath condensate from LAM subjects and was increased by aspirin treatment, indicative of functional COX-2 expression in the LAM airway. Targeting COX-2 and prostaglandin pathways may have therapeutic value in LAM and TSC-related diseases, and possibly in other conditions associated with mTOR-hyperactivation.

Citation Format: Chenggang Li, Po-Shun Lee, Yang Sun, Xiaoxiao Gu, Erik Zhang, Chin-Lee Wu, Andrey Parkhitko, Neil Aurrichio, Tasha Morrison, John Blenis, Kai-Feng Xu, Elizabeth Petri Henske, Bruce Levy, David Kwiatkowski, Jane Yu. Aspirin inhibits cyclooxygenase 2-mediated prostaglandin production and tumorigenesisin a preclinical model of tuberous sclerosis complex. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B09.
Abstract B27: Characterization of tumor-host interactions that promote liver metastasis of colorectal cancer
Authors: Pena Maria Marjorette O. , Zhang Yu , Davis Celestia
Published: May 2015

The leading cause of death from colorectal cancer is metastasis. The five year survival rate drops from 95% when the disease is at the localized stage to approximately 12% when metastasis has occurred. Because of its asymptomatic progression, metastasis is often detected at the final stage when little can be done, and little is now regarding the mechanisms that direct the early steps when intervention can potentially have an impact on its progression. In order to elucidate the mechanisms, we developed a mouse model of CRC metastasis to the liver, the frequent target organ of metastasis by cecum implantation of CT26 mouse colon adenocarcinoma cells into immunocompetent host Balb/cByJ mice. This model can recapitulate disease progression from the growth of the primary tumor to establishment of metastatic lesions within a defined time frame. Using this model, we isolated isogenic cell lines that gave rise to a high frequency of spontaneous metastasis to the liver. Implantation of the most highly metastatic CT26-FL3 cell line gave rise to liver metastasis in 90% of host mice, ten-fold higher than the parental CT26 cell line, in as early as 10 days. Initial characterization revealed that these cells expressed elevated levels of genes whose products promoted invasion, migration, and mobilization of bone marrow derived cells (BMDCs) to the pre-metastatic liver. We determined the genetic signatures of the CT26 and CT26-FL3 cells and that of the pre-metastatic and metastatic liver environment by microarray analyses to identify genes that might mediate the crosstalk between the primary tumor and target organ to promote progression of liver metastasis. The results identified genes encoding proteins that might act as potent effectors of the immune response that are induced in the early stage of metastasis. We characterize these proteins and assess their potential as viable biomarkers for early diagnosis of metastatic disease or as targets to deter metastatic progression. Our mouse model, therefore, can be an important platform to characterize metastatic cells and to elucidate tumor-host interactions and mechanisms that drive liver metastasis of CRC. In addition, it can be a valuable tool for pre-clinical evaluation of therapies targeted against metastatic CRC.

Citation Format: Maria Marjorette O. Pena, Yu Zhang, Celestia Davis. Characterization of tumor-host interactions that promote liver metastasis of colorectal cancer. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B27.
Abstract B32: The Survivin-deltaEx3 isoform drives microvascular proliferation and malignant progression in proneural gliomas
Authors: Rao Ganesh , Doucette Tiffany , Yang Yuhui , Fuller Greg , Rao Arvind
Published: May 2015

Introduction: Survivin expression correlates with poor prognosis in high-grade glioma. The influence of Survivin isoforms on outcome is poorly understood. We analyzed the dominant anti-apoptotic transcript variants of Survivin using expression data and modeled them in vivo.

Methods: TCGA mRNA expression data was used to study Survivin in low- and high-grade gliomas including proneural(PN) and mesenchymal(Mes) subtypes. We expressed the anti-apoptotic isoforms of Survivin (transcript variants 1 and 2) in vivo using the RCAS/Ntv-a system.

Results: In low-grade glioma, increased expression of Survivin occurred in 22/167(13.2%) cases, and was associated with shortened survival (log rank test, p=0.005). In high-grade gliomas, increased expression occurred in 258/547(47%) cases. Variant 1 was expressed in 215/258(83%) cases, and variant 2 was expressed in 26/258(10%) cases. Median survival was 451 days and 382 days for variant 1 and 2 expressors respectively. Survivin was preferentially expressed in PN relative to Mes gliomas(chi squared, p<0.0001). In PN gliomas, Survivin was expressed in 94/141(67%) cases which had shorter progression free survival(log rank test, p=0.04). Median survival in PN gliomas was 447 days for Variant 1 expressors and 394 days for Variant 2 expressors. In mice, ectopic expression of variant 1 yielded tumors in 28/30(93%) of mice and only 7/28(25%) were high-grade. Ectopic expression of Variant 2 yielded tumors in 27/28(96%) of mice and the majority (22/27,(81%)) were high grade(chi squared, p<0.0001). CD31 expression (to quantify angiogenesis) was significantly higher in Variant 2-derived tumors than Variant 1(t test, p<0.0001). Tumor free survival was shorter in mice with variant-2 derived tumors(log rank test, p=0.01)

Conclusions: Survivin expression in low-grade gliomas is associated with poor survival and is more common in PN gliomas. Poorer survival correlates with Survivin Variant 2, relative to the common isoform. In a PN murine glioma model, variant 2 promotes malignant progression, angiogenesis and shortens tumor-free survival.

Note: This abstract was not presented at the conference.

Citation Format: Ganesh Rao, Tiffany Doucette, Yuhui Yang, Greg Fuller, Arvind Rao. The Survivin-deltaEx3 isoform drives microvascular proliferation and malignant progression in proneural gliomas. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B32.
Abstract B34: High-throughput synthetic lethal interaction screening in model organisms as a strategy for the identification of novel therapeutic targets in cancer
Authors: Srivas Rohith , Shen John Paul , Li Jian Feng , Licon Katherine , Wang Ze Zhong , Bojoquez-Gomez Ana , Xu Lucy , Gross Andrew , Bean Gordon , Sobol Robert , Ideker Trey
Published: May 2015

Loss of tumor suppressor activity is a near universal feature of cancer. Synthetic lethality, in which combined perturbation of two genes results in cell death, has been proposed as a strategy to identify drug targets that specifically attack cancers deficient in a tumor suppressor (TS) gene. To develop a catalog of such combinations, we screened for synthetic-lethal interactions among all yeast orthologs of known TS and druggable genes, resulting in quantitative growth rates for 130,000 pairwise genetic mutants. Similar interaction profiles were highly predictive of TS genes in the same pathway, identifying a novel role for NDNL2/NSE3 in the G1/S checkpoint. TS/drug combinations likely to induce cancer cell death were prioritized using multiple criteria, including conservation across divergent species. Among the top hits were putative interactions involving either BRCA1 or XRCC3 with histone deacetylases, as well as Rad17 with CHK1/2. These were confirmed using small molecule inhibitors and short-pin RNA silencing in human cancer cell lines. This work provides a resource of >300 deeply conserved interactions among tumor suppressors and matched drug targets.

Citation Format: Rohith Srivas, John Paul Shen, Jian Feng Li, Katherine Licon, Ze Zhong Wang, Ana Bojoquez-Gomez, Lucy Xu, Andrew Gross, Gordon Bean, Robert Sobol, Trey Ideker. High-throughput synthetic lethal interaction screening in model organisms as a strategy for the identification of novel therapeutic targets in cancer. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B34.
Abstract B46: Adult stem cell quiescence as a tumor suppressor mechanism in squamous tumors
Authors: White Andrew C. , Khuu Joan , Dang Christine , Tran Kathy , Liu Anqi , Lowry Bill
Published: May 2015

Adult stem cells cycle between periods of quiescence and activation with varied periodicities. In many organs, adult stem cells are also uniquely poised to serve as cancer cells of origin. It is unclear, however, whether tumorigenesis is influenced by the activation state of the adult stem cell. Since hair follicle stem cells (HFSCs) act as cancer cells of origin for cutaneous squamous cell carcinoma (SCC) and undergo defined cycles of quiescence and activation, we sought to determine if SCC initiation was dependent on stem cell activity. These data show that HFSCs are unable to initiate tumors during the quiescent phase of the hair cycle, indicating that the mechanisms that keep HFSCs dormant are dominant to gain of oncogenes (Ras) or loss of tumor suppressors (p53). Instead, prolonged oncogenic stimuli only exert their effects when HFSC quiescence mechanisms are removed by normal HFSC activation. Thus, stem cell quiescence is a novel form of tumor suppression in hair follicle stem cells. Furthermore, Pten activity is necessary for quiescence based tumor suppression, since Pten deletion alleviates this stem cell specific ability. The loss of Pten in this context differentially regulates a number of signaling pathways, all of which led to phenotype progression without induction of a typical anagen cycle. This model suggests a mechanism with potentially broad implications, in which adult stem cells that contain mutations sufficient to initiate cancer could lay dormant for long periods of time without presentation of disease.

Citation Format: Andrew C. White, Joan Khuu, Christine Dang, Kathy Tran, Anqi Liu, Bill Lowry. Adult stem cell quiescence as a tumor suppressor mechanism in squamous tumors. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr B46.
Abstract IA1: Modeling pancreatic cancer biology and medicine
Authors: Tuveson David A.
Published: May 2015

Pancreatic ductal adenocarcinoma (PDA) tumors characteristically contain an abundant desmoplastic stroma that impedes drug delivery and promotes drug resistance. We have found through genetic, cellular and pharmacological approaches that a variety of cell intrinsic and extrinsic pathways promote pancreatic cancer progression and drug resistance, and methods to modulate such processes will be discussed here. These observations were made first in genetically engineered mouse models of PDA, and have prompted multiple translational efforts to seek patient benefit. Finally, methods to accelerate the discovery to translation process using primary tissue organoids will be introduced.

Citation Format: David A. Tuveson. Modeling pancreatic cancer biology and medicine. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr IA1.
Abstract IA19: Canine cancer genetics: What dogs can tell us about ourselves
Authors: Ostrander Elaine A.
Published: May 2015

The 165 domestic US dogs breeds display tremendous morphologic variation, making them an appealing model for the identification of genetic regulators of vertebrate shape and development and disease susceptibility. We have genotyped over 1000 dogs representing 85 domestic breeds to generate a reference dataset on over 60,000 informative SNPs per dog. This, combined with morphometric data has allowed us to map and sequence loci that control various features of breed-specific traits related to shape and size. In addition to helping us understand the genetics of morphologic variation, the underlying loci have also helped us understand the genetics of growth regulation. We now have a clearer sense of how variation is created in body size, leg length, head shape and other features that define various breeds of dog because of such studies. The domestic dog is also a robust model for studying the genetics of disease susceptibility as some breeds harbor an elevated risk, particularly for types of cancer, in spite of a relatively simple genetic architecture that is common to all dogs. One example of breed-specific disease propensity is squamous cell carcinoma of the digit (SCCoD), a locally aggressive cancer that frequently causes lytic bone lesions and multiple toe recurrence. SCCoD is uncommon in most dog breeds, but occurs in Schnauzers, Briards, and Standard Poodles, who are at about a 10-fold increased risk. Another cancer of interest to humans and dogs is transitional cell carcinoma of the bladder, which we observe at increased risk in Scottish Terriers (22 fold increased risk), West Highland White Terriers and Shelties. A final example is histiocytic carcinoma, which is common to Flat Coated Retrievers and Bernese Mountain dogs. Advances in genomic technologies, together with valued clinical collaborations, have allowed us to undertake studies aimed at understanding the genetic susceptibility of each. Key to advancing these studies has been the availability of dense SNP chips and the ever-increasing amount of data on a variety of dog breeds. We will report on our progress on each.

Citation Format: Elaine A. Ostrander. Canine cancer genetics: What dogs can tell us about ourselves. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr IA19.
Abstract IA2: Developing therapeutics using the zebrafish
Authors: Zon Leonard I.
Published: May 2015

The zebrafish is a wonderful disease model, and it is now possible to develop new therapies to treat human disease. A screen for blood stem cells in the developing aorta led to the discovery of PGE2 as a regulator of stem cell engraftment. After studies with mouse and human hematopoietic cells, a clinical trial proceeded to test PGE2 in cord blood transplantation. In 12 leukemic patients receiving 2 cord blood units, one treated with dmPGE2, 10 patients engrafted with the treated cord blood. The neutrophils and platelets recovered more quickly than the untreated cord blood. Another chemical, leflunomide, was found in zebrafish to block neural crest development. Leflunomide also suppressed neural crest gene transcription in human melanomas, and reduced the rate of human tumor formation in mouse xenografts. The effect was stronger in combination with a BRAF inhibitor known to block cell proliferation. This has led to a clinical trial in which 43 patients will be treated for metastaic melanoma. To date, three patients have been treated. In another example, a chemical suppressor screen was done on the rps29 mutant that resembles Diamond Blackfan anemia. Calmodulin antagonists rescue the defect in hematopoiesis. These antagonists also rescue the hematopoietic block found in human CD34 cells treated with an shRNA to rps19. This suggests that calmodulin antagonists could be used to treat patient with Diamond Blackfan anemia. The zebrafish offers an excellent opportunity to find new therapeutics.

Citation Format: Leonard I. Zon. Developing therapeutics using the zebrafish. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr IA2.
Abstract IA22: Modeling recurrent metastatic melanoma in the mouse
Authors: Merlino Glenn T. , Day Chi-Ping , Mishra Pravin , Guo Theresa , Zaida Raza , Davis Sean , Meltzer Paul , Noonan Frances , Fabo Edward De , Ohler-Weaver Zoe , Dyke Terry Van
Published: May 2015

Recurrence and metastasis following resection and therapy are the most critical problems in progressive cancers and the main causes of cancer-related death. This problem is magnified in cutaneous malignant melanoma, which is highly metastatic in advanced stages and generally resistant to chemotherapy. Although new drugs such as Vemurafenib successfully target BRAFV600E and typically demonstrate a significant clinical response, progressive melanomas recur resulting in near uniform patient mortality. Dissection of processes underpinning recurrent and metastatic melanoma is certain to identify new therapeutic targets for more efficacious treatment. However, current preclinical studies do not model progressive recurrent disease, but rather rely on the growth response of human melanoma cell lines subcutaneously xenografted into immunocompromised mice as the efficacy endpoint; these studies have shown poor predictive power for clinical activity. Therefore we have designed new and improved genetically engineered mouse (GEM) models of progressive melanoma. These are being used to test targeted and immune-based therapies singly and in combination, and to study mechanisms associated with the resistance of recurrent/metastatic melanoma to promising clinical drugs.

To identify novel targets for advanced disease we hypothesized that metastatic melanomas can exploit hard-wired pathways employed by migratory embryonic melanocytes, but not mature melanocytes, to achieve a more aggressive malignant phenotype. We had previously generated a GEM model (iDCT-GFP) that expresses Green Fluorescent Protein specifically in all melanocytic cells in a doxycycline-regulatable manner. The iDCT-GFP mouse was used in concert with FACS to isolate melanoblasts from key developmental stages, sequence their transcriptomes using RNA-Seq, and identify genes/pathways common to metastatic melanoma cells. We have thus generated a full library of the genes expressed during embryonic development of the melanocyte. A detailed comparative analysis of mouse melanoblast gene expression profiles with human metastatic melanoma cells was then performed, identifying what we believe to be a small number of critical genes common to both. We anticipate that this approach will enhance our understanding of this fatal disease at both mechanistic and prognostic levels, and facilitate the identification of novel therapeutic targets for the treatment of metastatic melanoma.

Citation Format: Glenn T. Merlino, Chi-Ping Day, Pravin Mishra, Theresa Guo, Raza Zaida, Sean Davis, Paul Meltzer, Frances Noonan, Edward De Fabo, Zoe Ohler-Weaver, Terry Van Dyke. Modeling recurrent metastatic melanoma in the mouse. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr IA22.
Abstract IA9: Studying therapy response and resistance in mouse models of human breast cancer
Authors: Jonkers Jos
Published: May 2015

Mouse models of human cancer not only permit us to gain a detailed insight into the specific genetic changes that drive tumor development and metastasis but also provide powerful tools to study the mechanisms underlying drug response and acquired resistance. Once these processes are understood in sufficient detail it may be possible to design combination therapies that not only cause complete remissions but also eliminate remnant cells that might elicit recurrent disease.

We have developed genetically engineered mouse models (GEMMs) of E-cadherin mutated lobular breast cancer. These mice develop mammary tumors that closely resemble the lobular morphology and the metastatic spectrum of the cognate tumors in humans. We have used Sleeping Beauty (SB) based insertional mutagenesis (IM) screens in conditional E-cadherin mutant mice to identify cancer genes that collaborate with E-cadherin loss in mammary tumorigenesis. Approximately 50% of all tumors carry activating SB insertions in Fgfr2. These tumors are highly sensitive to FGFR inhibitors but eventually become resistant. We are currently analyzing SB insertions in FGFRi-resistant tumors to identify genes that are causal to the resistance phenotype.

We have also established GEMMs and patient-derived xenograft (PDX) models for BRCA1-deficient triple-negative breast cancer. These mice develop mammary tumors that are characterized by genomic instability and hypersensitivity to DNA-damaging agents, including platinum drugs and PARP inhibitors. Nevertheless, none of these drugs are curative: tumors grow back after drug treatment and eventually become resistant. We have used DNA methylation analysis and focused or whole-exome sequencing to identify resistance mechanisms in matched pairs of therapy-sensitive and –resistant BRCA1-deficient mammary tumors from our GEMMs and PDX models. We found that resistance of BRCA1-deficient GEMM tumors to the PARP inhibitor olaparib can be induced by several mechanisms, including activation of P-glycoprotein drug efflux transporters, type of BRCA1 founder mutation and 53BP1 loss. Therapy resistance of BRCA1-mutated PDX tumors is caused by additional intragenic deletions that lead to restoration of the open reading frame. Therapy resistance of BRCA1-methylated PDX tumors is driven by loss of BRCA1 promoter methylation or by a novel resistance mechanism involving de novo BRCA1 gene fusions created by intrachromosomal genomic rearrangements.

Citation Format: Jos Jonkers. Studying therapy response and resistance in mouse models of human breast cancer. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr IA9.
Abstract PR08: Man's best friend for cancer driver-passenger discrimination
Authors: Zhao Shaying
Published: May 2015

Spontaneously occurring canine cancer represents one of the best cancer models. Herein we report a novel dog human comparison strategy that utilizes inter-species genomic arrangements occurring during the past >75 million years to tackle a central aim of cancer research, namely cancer driver passenger discrimination. After showing that spontaneous canine colorectal cancers share similar molecular pathogenesis mechanisms as their human counterparts (Tang et al., 2010; Youmans et al., 2012), we compared copy number abnormalities between the two species (Tang et al., 2013). This led to the identification of 73 driver candidate genes (DCGs) and 38 passenger candidate genes (PCGs). Importantly, DCGs differ from PCGs in every analysis conducted to assess their cancer relevance. Moreover, while PCGs' functions appear random, DCGs' are significantly associated with cell proliferation and epithelial cell polarities. We are conducting 3D culture to validate these functions, leading to the discovery of several new tumor suppressors and cell polarity genes.

Besides colorectal cancer, we have also successfully applied this dog-human comparison strategy on triple negative breast cancers, of which copy number abnormalities are extensive. In summary, we have developed a novel approach to efficiently analyze the massive cancer genomic data generated by TCGA and others for cancer driver discovery.

Tang, J., Le, S., Sun, L., Yan, X., Zhang, M., Macleod, J., Leroy, B., Northrup, N., Ellis, A., Yeatman, T. J., et al. (2010). Copy number abnormalities in sporadic canine colorectal cancers. Genome research 20, 341-350.

Tang, J., Li, Y., Lyon, K., Camps, J., Dalton, S., Ried, T., and Zhao, S. (2013). Cancer driver-passenger distinction via sporadic human and dog cancer comparison: a proof-of-principle study with colorectal cancer. Oncogene.

Youmans, L., Taylor, C., Shin, E., Harrell, A., Ellis, A. E., Seguin, B., Ji, X., and Zhao, S. (2012). Frequent alteration of the tumor suppressor gene APC in sporadic canine colorectal tumors. PloS one 7, e50813.

This abstract is also presented as Poster B51.

Citation Format: Shaying Zhao. Man's best friend for cancer driver-passenger discrimination. [abstract]. In: Proceedings of the AACR Special Conference: The Translational Impact of Model Organisms in Cancer; Nov 5-8, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(11 Suppl):Abstract nr PR08.
Abstract A02: Pak1 kinase inhibition sensitizes 11q13 amplified breast cancer cells to platinum based chemotherapy via downregulation of Fanconi anemia genes
Authors: Arias-Romero Luis E. , Villamar-Cruz Olga , Chernoff Jonathan
Published: May 2015

Activating mutations in Ras GTPases frequently occur in many types of human cancers but are rarely detected in breast tumors. However, activation of the Ras/Raf/MEK/ERK pathway is commonly observed in human breast cancers, suggesting that other genetic alterations lead to activation of this signaling pathway. Several studies have shown that signaling through the Ras/Raf/MEK/ERK pathway can be influenced by Pak1 kinase, a downstream effector of the Ras-related C3 botulinum toxin substrate 1 (Rac1) GTPase. In addition, it has been shown that Pak1 is amplified in several human cancer types, including 25-30% of breast tumor samples and cancer cell lines, and that its kinase activity is necessary for Ras mediated transformation.

In this work, we performed a comparative gene profiling study in order to identify differentially regulated genes between wild-type and Pak1 deficient mouse and human breast cancer cells. Several genes involved in the Fanconi Anemia/BRCA pathway - a DNA-damage response signaling pathway that is essential for repairing DNA interstrand cross-links induced by DNA-damaging agents like cisplatin and doxorubicin - were down-regulated in Pak1 deficient cells. The reduced expression of FANCD2 and FANCI was confirmed by qPCR and western blot in Pak1-depleted human breast cancer cells with or without 11q13 amplification. Interestingly, the depletion or chemical inhibition of Pak1 in 11q13 amplified breast cancer cells treated with cisplatin, compromised the ability of these cells to repair DNA by homologous recombination, induced cell cycle arrest, promoted apoptosis and resulted in reduced colony formation. In contrast, the inhibition or depletion of Pak1 had little effect on these cellular processes in Pak1-non-amplified breast cancer cells.

Because reduced Pak1 activity impaired Fanconi Anemia/BRCA signaling and consequently, repair by homologous recombination, inhibition of Pak1 represents a plausible strategy for expanding the utility of DNA-damaging treatments to Fanconi Anemia/BRCA-proficient 11q13 amplified breast cancers.

Citation Format: Luis E. Arias-Romero, Olga Villamar-Cruz, Jonathan Chernoff. Pak1 kinase inhibition sensitizes 11q13 amplified breast cancer cells to platinum based chemotherapy via downregulation of Fanconi anemia genes. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr A02. doi: 10.1158/1557-3125.RASONC14-A02
Abstract A12: Erk2 phosphorylates Drp1 to promote mitochondrial fission and Ras-driven tumor growth.
Authors: Kashatus David
Published: May 2015

Oncogenic Ras mutations lead to activation of several downstream effector pathways that promote a tumorigenic phenotype. As targeting Ras directly has proven difficult, a great deal of effort has been expended trying to understand these downstream effector pathways and the biological processes that underlie their pro-tumorigenic activity. Several of the processes affected by aberrant Ras signaling, including apoptosis, metabolic reprogramming and proliferation, are tightly linked to mitochondrial function. Furthermore, each of these processes can be affected by changes in mitochondrial dynamics. As such, we hypothesized that altering the balance of mitochondrial fusion and fission might be a mechanism through which Ras promotes the phenotypes associated with tumor progression and thus might represent an attractive new target for the treatment of Ras-driven cancers. Here, we show that expression of oncogenic Ras leads to an increase in mitochondrial fragmentation and that blocking this phenotype, through knockdown of the mitochondrial fission-mediating GTPase Drp1, inhibits Ras-driven tumor growth. Mechanistically, this Ras-driven mitochondrial fission occurs through activation of the MAP Kinase pathway, which promotes fission through Erk2-mediated phosphorylation of Drp1 on Serine 616. Furthermore, Drp1 phospho-S616 levels are increased in pancreatic cancer tissues and cell lines and inhibition of this phosphorylation is sufficient to block Ras-mediated mitochondrial fission and Ras-induced tumor growth. Collectively, these data suggest that the mitochondrial fission machinery may be a novel target for treating Ras-driven malignancies.

Citation Format: David Kashatus. Erk2 phosphorylates Drp1 to promote mitochondrial fission and Ras-driven tumor growth.. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr A12. doi: 10.1158/1557-3125.RASONC14-A12
Abstract A13: Constitutively-active HRAS suppresses stochastic Erk activity pulses in Madin-Darby canine kidney cells
Authors: Kawabata Noriyuki , Matsuda Michiyuki
Published: May 2015

The EGFR-Ras-ERK pathway is a major growth signaling cascade in many human cancers. Consequently, constitutive activation of Ras, which is found in 30% of human cancers, is believed to lead to constitutive ERK activation and, thereby, uncontrolled cell growth. Recently, we have reported that the cell growth is controlled not only by the basal ERK activity but also by the frequency of stochastic ERK activity pulses. In the present study, we have evaluated the effect of Ras on the temporal dynamics of Erk activity by using fluorescent resonance energy transfer (FRET) biosensors. We found that, in Madin-Darby Canine kidney (MDCK) cells expressing constitutively active HRAS (HRASV12), ERK activity stimulated by epidermal growth factor (EGF) and 12-O-tetradecanoylphorbol-13-acetate (TPA), was markedly attenuated in comparison with the parent MDCK cells. Furthermore, the stochastic ERK activity pulses observed in the parent MDCK cells were almost completely abolished in the HRASV12-expressing MDCK cells. These observations have revealed that the temporal regulation of ERK activity is significantly different between normal and HRASV12-expressing cells.

Citation Format: Noriyuki Kawabata, Michiyuki Matsuda. Constitutively-active HRAS suppresses stochastic Erk activity pulses in Madin-Darby canine kidney cells. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr A13. doi: 10.1158/1557-3125.RASONC14-A13
Abstract A16: Overexpression and ubiquitination of kinase suppressor of Ras 1 (KSR1) in human colon tumor cells
Authors: McCall Jamie L. , Kono Ken , Fisher Kurt W. , Furukawa Manabu , Lewis Robert E.
Published: May 2015

Kinase Suppressor of Ras 1 (KSR1) is required for oncogenic Ras-induced transformation in mouse embryonic fibroblasts (MEFs) and human colon tumor cells, but is dispensable for normal cellular development. It is also overexpressed in a variety of human tumors, including human colon tumor cells. Seven human colon tumor cell lines with mutated and activated Ras (GEO, CBS, FET, SW480, HCT15, DLD1, and HCT116), one with wild type Ras (CaCo2), and non-transformed human colonic epithelial cells (HCECs) were assessed for KSR1 by western blot. Compared to HCECs, all eight tumor cell lines showed a marked decrease in electrophoretic motility. Seven of eight cell lines had a clear increase in KSR1 expression regardless of Ras mutation status. The purpose of the study is to examine the mechanism by which KSR1 is up-regulated in cancer cells.

Previous studies indicate that KSR proteins interact with multiple E3 ubiquitin ligase complexes including members homologous to the E6AP carboxyl terminus (HECT) domain family and the really interesting new gene (RING) family, including Cullin (Cul) 1, Cul4A, Cul4B, Cul7, damage-specific DNA binding protein 1 (DDB1), and DDB1-Cullin associating factor 1 (DCAF1), and ubiquitin protein ligase E3 component N-recognin 5 (UBR5/EDD1). Using tagged expression vectors and immunoprecipitation techniques, we investigated whether KSR1 is a substrate or a component of E3 ligase complexes. Both FLAG-tagged and endogenous KSR1 are ubiquitinated in the human colon tumor cell line, HCT-116. In HEK 293T cells, truncated KSR1 constructs were used to determine that KSR1 ubiquitination is dependent on the presence of the putative kinase domain in the C-terminal region. Furthermore, the kinase domain is sufficient for KSR1 ubiquitination by Cul4A/4B RING ligases (CRLs); however, silencing of Cul4A/4B by RNAi does not inhibit KSR1 ubiquitination. These data indicate that multiple Cullin family members may function to ubiquitinate KSR1. Additionally, KSR1 does not exclusively bind to Cullins, but also interacts with other components of the multi-subunit CRLs, including DDB1 and DCAF1. Therefore, KSR1 may not only be a direct substrate but also a member of the large complex helping to modulate activity of the CRL. Overall, these data suggest that Cul4A/4B-dependent ubiquitination of the KSR1 putative kinase may function to modulate KSR1-dependent signaling.

Citation Format: Jamie L. McCall, Ken Kono, Kurt W. Fisher, Manabu Furukawa, Robert E. Lewis. Overexpression and ubiquitination of kinase suppressor of Ras 1 (KSR1) in human colon tumor cells. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr A16. doi: 10.1158/1557-3125.RASONC14-A16
Abstract A19: A Ras-Arf-Egr-C/EBPβ axis underlying oncogene-induced senescence and cancer
Authors: Salotti Jacqueline , Sakchaisri Krisada , Johnson Peter F.
Published: May 2015

In normal cells, persistent oncogenic Ras activation triggers senescence, an intrinsic tumor suppression mechanism that protects cells from malignant transformation. Oncogene-induced senescence (OIS) is dependent on tumor suppressors such as p19/p14Arf, and loss of those genes facilitates transformation by oncogenic Ras. We previously reported that C/EBPβ, a transcription factor that has both pro- and anti-oncogenic functions, contributes to OIS in primary fibroblasts. Notably, C/EBPβ is down-regulated in H- or K-RasV12-transformed NIH 3T3 cells in a manner that requires loss of p19Arf. The potential role of C/EBPβ down-regulation in RasV12-induced transformation prompted us to investigate the mechanisms of Cebpb gene transcription. Here we show that Cebpb is an early growth factor-induced gene whose induction is suppressed by H-RasV12 in NIH 3T3 cells and p19Arf-/- MEFs. The early growth response (Egr) transcription factors are also down-regulated by H-RasV12 in these cells. Over-expression of any of Egr proteins (Egr1-4) restored C/EBPβ levels in 3T3Ras cells. Interestingly, Egrs induce growth arrest and senescence in 3T3Ras cells in a manner that is only partially dependent on reactivation of C/EBPβ. Egr1-4 proteins stimulated transcription from a promoter-reporter construct containing ∼3 kb of the Cebpb 5' flanking region. The proximal Cebpb promoter contains several putative Egr binding motifs, and mutating three of these sites disrupted Egr-mediated transactivation of the Cebpb promoter. Chromatin immunoprecipitation assays showed that ectopically expressed and endogenous Egrs bind to the Cebpb proximal promoter. Furthermore, microarray data from Oncomine show a strong correlation between CEBPB and EGR expression in human tumor samples, regardless of whether C/EBPβ levels increase or decrease in tumors compared to normal tissue. Since CEBPB and EGRs are down-regulated in lung adenocarcinomas and their elevated expression is associated with a better prognosis in lung cancer patients (Prognoscan), we over-expressed Egrs in A549 lung adenocarcinoma cells, which carry a KRAS mutation. Ectopic Egr2-4 induced CEBPB mRNA expression and dramatically suppressed cell proliferation. Collectively, our data indicate that decreased Egr levels account for oncogenic Ras-induced down-regulation of C/EBPβ in certain transformed cells, and restoration of Egrs induces growth arrest and C/EBPβ expression. Our findings identify the Egr-C/EBPβ axis as an important pathway in determining the cellular response (transformation or senescence) to oncogenic Ras-Arf signaling.

Citation Format: Jacqueline Salotti, Krisada Sakchaisri, Peter F. Johnson. A Ras-Arf-Egr-C/EBPβ axis underlying oncogene-induced senescence and cancer. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr A19. doi: 10.1158/1557-3125.RASONC14-A19
Abstract A43: RUNX3 and pRB form a complex and regulate restriction-point commitment
Authors: Chi Xin-Zi , Lee You-Soub , Lee Jung-Won , Lee You-Mie , Ito Yoshiaki , Bae Suk-Chul
Published: May 2015

Throughout the cell cycle, a cell monitors cumulative exposure to specific signals over time and makes a critical decision to pass through the restriction (R) point. Although the R-point decision is fundamental to normal differentiation and G1-S transition, the mechanism for the decision has been poorly understood. RUNX3 functions as a tumor suppressor and is frequently inactivated by DNA hyper-methylation in the stomach, bladder, colon, and lung. Recently, we have shown that adenovirus-Cre infected LSL-K-RasG12D mice induced lung adenocarcinoma (ADC) in prolonged latency (median survival, 220 days) and Runx3f/f/LSL-K-RasG12D mice rapidly induced ADC (median survival, 79 days), indicating a strong tumor suppressor activity of Runx3 against oncogenic K-Ras (Lee et., 2013. Cancer Cell. 2013 Vol. 24, pp 603-616). In the present study, we found that targeted disruption of Runx3 results in a delay in pRB phosphorylation and cell cycle progression through the R-point in mouse embryonic fibroblast cells. During the R-point interval, RUNX3 transiently formed a complex with pRB and BRD2 and induced Cdkn1a (p21Waf1/Cip1/Sdi1; p21). The complex was dissociated when by Cyclin D1 which was induced 4 hours after serum stimulation and p21 expression was turned off. However, oncogenic K-Ras maintained the complex. These results identify the series of molecular events associated with R-point commitment and provide an insight into the relationship between R-point commitment and oncogene surveillance.

Note: This abstract was not presented at the conference.

Citation Format: Xin-Zi Chi, You-Soub Lee, Jung-Won Lee, You-Mie Lee, Yoshiaki Ito, Suk-Chul Bae. RUNX3 and pRB form a complex and regulate restriction-point commitment. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr A43. doi: 10.1158/1557-3125.RASONC14-A43
Abstract A45: A potential therapeutic strategy for treatment of colorectal cancers through regulating Ras stability via inhibition of Wnt/β-catenin pathway
Authors: Cha Pu-Hyeon , Cho Yong-Hee , Jeong Woo-Jeong , Choi Kang-Yell
Published: May 2015

Ras is a well-characterized proto-oncogene, and its various mutations contribute to transformation and tumorigenesis in a wide variety of human cancers. Although the GTP/GDP loading switch is known as a major regulatory mechanism of Ras, other mechanisms affecting Ras activity are poorly understood. Here, we report a mechanism for controlling Ras activity by regulating its degradation and describe this regulatory mechanism in the suppression of cellular transformation and tumors induced by Ras mutations. We found that negative regulators of Wnt/β-catenin signaling contributed to the polyubiquitin-dependent degradation of Ras following phosphorylation by glycogen synthase kinase 3β (GSK3β) and subsequent recruitment of β-TrCP-E3 ligase. We found a positive association between tumorigenesis and Ras stabilization due to the aberrant activation of Wnt/β-catenin signaling. Our results indicate an essential role for phosphorylation and degradation of Ras and suppression of Ras-induced transformation via the Wnt/β-catenin pathway and provide insight into the role of this novel regulatory mechanism for Ras in tumorigenesis of colorectal cancers (CRCs). Because both Ras and Wnt/β-catenin pathways are frequently activated in CRCs, these results suggest that the regulation of Ras stability through inhibition of the Wnt/β-catenin pathway could be an ideal therapeutic approach for treatment of CRC.

Citation Format: Pu-Hyeon Cha, Yong-Hee Cho, Woo-Jeong Jeong, Kang-Yell Choi. A potential therapeutic strategy for treatment of colorectal cancers through regulating Ras stability via inhibition of Wnt/β-catenin pathway. [abstract]. In: Proceedings of the AACR Special Conference on RAS Oncogenes: From Biology to Therapy; Feb 24-27, 2014; Lake Buena Vista, FL. Philadelphia (PA): AACR; Mol Cancer Res 2014;12(12 Suppl):Abstract nr A45. doi: 10.1158/1557-3125.RASONC14-A45