Comparative transcriptome analysis of Ptf1aCre;Kras,Brg1-/- vs. Ptf1a;Kras;p53+/- subcutaneous pancreatic ductal adenocarcinoma
ABSTRACT: In this experiment the RNA of s.c. grown tumors of cancer cell lines of murine Ptf1aCre;Kras,Brg1-/- vs. Ptf1a;Kras;p53+/- PDA was isolated and analyzed for gene expression. Ptf1aCre;Kras,Brg1-/- s.c. PDA grows more benign as compared to Ptf1a;Kras;p53+/- PDA; and the rationale of this study was to identify genes responsible for this different biological behavior. Total RNA of s.c. tumors of Ptf1aCre;Kras,Brg1-/- vs. Ptf1a;Kras;p53+/- cancer cell lines was isolated, purified and analyzed on the deep sequencing platform.
Project description:In this experiment the RNA of s.c. grown tumors of cancer cell lines of murine Ptf1aCre;Kras,Brg1-/- vs. Ptf1a;Kras;p53+/- PDA was isolated and analyzed for gene expression. Ptf1aCre;Kras,Brg1-/- s.c. PDA grows more benign as compared to Ptf1a;Kras;p53+/- PDA; and the rationale of this study was to identify genes responsible for this different biological behavior. Overall design: Total RNA of s.c. tumors of Ptf1aCre;Kras,Brg1-/- vs. Ptf1a;Kras;p53+/- cancer cell lines was isolated, purified and analyzed on the deep sequencing platform.
Project description:Brahma related gene 1 (BRG1), a catalytic ATPase subunit of SWI/SNF chromatin remodeling complexes, is silenced in approximately 10% of human pancreatic ductal adenocarcinomas (PDA). We previously showed that BRG1 inhibits the formation of intraductal pancreatic mucinous neoplasm (IPMN) and IPMN-derived PDA from ductal cells. However, the role of BRG1 in pancreatic intraepithelial neoplasia (PanIN) from acinar cells remains elusive. Here, we investigated the role of BRG1 in PanIN initiation and maintenance and its underlying mechanisms. Exclusive elimination of Brg1 in acinar cells of Ptf1a-CreER; KrasG12D; Brg1f/f (KBC) mice impaired the formation of acinar-to-ductal metaplasia (ADM) and PanIN independent of the presence of p53 mutation. We found that Sox9 expression was down-regulated in both Brg1-depleted acinar cell explants and BRG1-depleted ADMs/PanINs. Sox9 overexpression rescued this PanIN-attenuated phenotype in KBC mice. Furthermore, Brg1-deletion in established PanIN by using an inducible dual recombinase system resulted in regression of the lesions in mice. Finally, expression of BRG1 and SOX9 was also positively correlated in human PanIN-derived PDAs. In summary, BRG1 is critical for both initiation and maintenance of PanIN. Mechanistically, this is mediated through positive regulation of SOX9 expression. Thus, the BRG1/SOX9 axis is a potential target for the prevention of PanIN-derived PDA. Overall design: Total pooled RNA from three individual acinar cell explants 24 h after Cre-expressing adenovirus infection were used. Mouse genotypes used for analysis were KrasG12D and KrasG12D; Brg1f/f.
Project description:Pancreatic Ductal Adenocarcinoma (PDA) develops predominantly through pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN) precursor lesions. Pancreatic acinar cells are reprogrammed to a “ductal like” state during PanIN-PDA formation. Here, we demonstrate a parallel mechanism operative in mature duct cells where they undergo “ductal retrogression” to form IPMN-PDA. Brg1, a catalytic subunit of the SWI/SNF complexes, plays a critical antagonistic role in IPMN-PDA development. In mature duct cells Brg1 inhibits the dedifferentiation that precedes neoplastic transformation, thus attenuating tumor initiation. In contrast, Brg1 promotes tumorigenesis in full-blown PDA by supporting a mesenchymal-like transcriptional landscape. We have exploited this duality of Brg1 functions to develop a novel therapeutic approach using an epigenetic drug JQ1. In summary, this study demonstrates the context-dependent roles of Brg1 and points to potential therapeutic treatment options based on epigenetic regulation in PDA. Duct cells were isolated from mice of 3 different genotypes and duct cells from 3 mice of each genotype were sequenced. For the put back experiments, control retrovirus and that expressing Brg1 were transdcued in Brg1 null IPMN mouse cell line.
Project description:Mutations of subunit genes of the SWI/SNF chromatin remodeling complexes were found in 12-23% of human Pancreatic Ductal Adenocarcinoma (PDAC). We previously showed that Brg1, a catalytic ATPase subunit of the SWI/SNF chromatin remodeling complexes, inhibits the formation of intraductal pancreatic mucinous neoplasms (IPMN) and IPMN-derived PDAC from ductal cells. On the other hand, ARID1A is the most frequent target of mutations in the SWI/SNF chromatin remodeling complexes in human PDAC. We found that Arid1a loss in the context of mutant Kras resulted in formation of IPMN and PDAC. We also found that the incidence of PDAC formation in Ptf1a-Cre; KrasG12D; Arid1af/f mice was markedly lower than that in Ptf1a-Cre; KrasG12D; Brg1f/f mice despite the similarities between Arid1a-deficient and Brg1-deficient IPMNs. We extracted total RNA from intraductal papillary mucinous neoplasms (IPMNs) in Ptf1a-Cre; KrasG12D; Arid1af/f and Ptf1a-Cre; KrasG12D; Brg1f/f mice and perform microarray analysis. Overall design: Analysis of mRNA from IPMNs in two Ptf1a-Cre; KrasG12D; Arid1af/f mice and three Ptf1a-Cre; KrasG12D; Brg1f/f mice.
Project description:We have carried out transcriptional profile analysis in WT MICE and bitransgenic Pdx1-cre/Kras*A MICE baring Pancreatic Ductal Adenocarcinoma Mouse models faithfully simulating human cancer are valuable for genetic identification of potential drug-targets but, among them, the most advantageous for practical use in subsequent preclinical testing of candidate therapeutic regimes are those exhibiting rapid tumor development. Considering that a KRAS mutation (predominantly in codon 12, such as KRASG12D; KRAS*) occurs with high frequency (~90%) in cases of human pancreatic ductal adenocarcinoma (PDA)1, we sought to develop a mouse PDA model that would exhibit high tumor incidence and short latency by ectopic overexpression of Kras*. Five WT mice and 6 bitransgenic Pdx1-cre/Kras*A MICE baring Pancreatic Ductal Adenocarcinoma were used to identify key genes in the formation of panceatic malignacies
Project description:Oncogenic mutations in tumor cells regulate signaling both within tumor cells and heterotypic stromal cells. However, whether oncogenes regulate tumor cell signaling via stromal cells is poorly understood. Here we show that oncogenic KRAS (KRAS-G12D) uniquely regulates tumor cell signaling via stromal cells. By combining cell-specific proteome labeling with phosphoproteomic multiplexing we conducted a multivariate analysis of heterocellular KRAS-G12D signaling in Pancreatic Ductal Adenocarcinoma (PDA) cells. By engaging heterotypic fibroblasts, KRAS-G12D drives unique reciprocal signaling in tumor cells to employ additional kinases and double the number of regulated signaling nodes from cell-autonomous KRAS-G12D. Heterocellular signaling produces a distinct tumor cell phosphoproteome, total proteome, and increase mitochondria capacity via an IGF1R/AXL-AKT axis. Reciprocal KRAS-G12D phenotypes require a heterocellular context and are unreachable by cell-autonomous KRAS-G12D alone. These results demonstrate oncogene signaling should be viewed as a heterocellular process and our existing homocellular perspective underrepresents the extent of oncogene signaling in cancer.
Project description:Cancer cells that express oncogenic alleles of RAS typically require sustained expression of the mutant allele for survival, but the molecular basis of this oncogene dependency remains incompletely understood. To identify genes that can functionally substitute for oncogenic RAS, we systematically expressed 15,294 open reading frames in a human KRAS-dependent colon cancer cell line engineered to express an inducible KRAS-specific shRNA. We found 147 genes that promoted survival in the setting of KRAS suppression. In this model, the transcriptional co-activator YAP1 rescued cell viability in KRAS-dependent cells upon suppression of KRAS and was required for KRAS-induced cell transformation. Acquired resistance to Kras suppression in a Kras-driven murine lung cancer model also involved increased YAP1 signaling. KRAS and YAP1 converge on the transcription factor FOS and activate a transcriptional program involved in regulating the epithelial-mesenchymal transition (EMT). Together, these findings implicate transcriptional regulation of EMT by YAP1 as a significant component of oncogenic RAS signaling Three biological replicates of primary lung adenocarcinoma cells derived from the Kras Lox-STOP-Lox-G12D;p53flox/flox (KP) mouse lung cancer model into which a doxycycline-inducible shRNA targeting Kras expressed from the 3’UTR of GFP was introduced (KP-KrasA cells) were analyzed at timepoints (days) D0, D4, and D21.
Project description:Primary pneumocytes from KRas;Atg5fl/+ and KRas;Atg5fl/fl littermates were cultured for 48 hours and infected with AdCre-GFP to induce expression of the KrasG12D oncogene and concomitant Atg5 deletion. The transcriptional profile of those cells was determined by mRNA sequencing and uncovered differential expression in cellular movement, inflammatory response and oxidative stress response. Comparison of transcriptomes from KRas;Atg5fl/+ and KRas;Atg5fl/fl pneumocytes
Project description:RNA-seq analysis documented mRNA changes in total pancreatic RNA preparations 14 days after Ptf1a inactivation. pancreas mRNA profiles of Tamoxifen treated adult control mice [Ptf1a(CreER/+)] and Ptf1a conditional knockout mice [Ptf1a(CreER/fl)] were generated by deep sequencing using an Illumina Hiseq 2500.