Project description:The proto-oncogene KRAS is mutated in a wide array of human cancers, most of which are aggressive and respond poorly to standard therapies. Although the identification of specific oncogenes has led to the development of clinically effective, molecularly targeted therapies in some cases, KRAS has remained refractory to this approach. An alternative strategy for targeting KRAS is to identify gene products that, when suppressed or inhibited, result in cell death only in the presence of an oncogenic allele. Here we have used systematic RNA interference (RNAi) to detect synthetic lethal partners of oncogenic KRAS and found that the non-canonical IkB kinase, TBK1, was selectively essential in cells that harbor mutant KRAS. Suppression of TBK1 induced apoptosis specifically in human cancer cell lines that depend on oncogenic KRAS expression. In these cells, TBK1 activated NF- B anti-apoptotic signals involving cREL and BCL-XL that were essential for survival, providing mechanistic insights into this synthetic lethal interaction. These observations identify TBK1 as a potential therapeutic target in KRAS mutant tumors and establish a general approach for the rational identification of co-dependent pathways in cancer. This SuperSeries is composed of the following subset Series:; GSE17643: Profiling of immortalized human lung epithelial cells following oncogenic KRAS expression and TBK1 suppression; GSE17671: Profiling of immortalized human lung epithelial cells following infection with oncogenic KRAS (G12V) Experiment Overall Design: Refer to individual Series
Project description:Oncogenic KRAS mutations are prevalent in colorectal cancer (CRC) and are associated with poor prognosis and resistance to therapy. There is a substantial diversity of KRAS mutant alleles observed in CRC. Emerging clinical and experimental analysis of common KRAS mutations suggest that each mutation differently influences the clinical properties of a disease and response to therapy. Although there is some evidence to suggest biological differences between mutant KRAS alleles, these are yet to be fully elucidated. One approach to study allelic variation involves the use of isogenic cell lines that express different endogenous Kras mutants. Here, we generated Kras isogenic Apc-/- mouse colon epithelial cell lines using CRISPR-driven genome editing by altering the original G12D Kras allele to G12V, G12R, or G13D. We utilized these cell lines to perform transcriptomic and proteomic analysis to compare different signaling properties between these mutants. Both screens indicate significant differences in pathways relating to cholesterol and lipid regulation that we validated with targeted metabolomic measurements and isotope tracing. We found that these processes are upregulated in G12V lines through increased expression of nuclear SREBP1 and higher activation of mTORC1. G12V cells showed higher expression of ACSS2 and ACSS2 inhibition sensitized G12V cells to MEK inhibition. Finally, we found that ACSS2 plays a crucial role early in the development of G12V mutant tumors, in contrast to G12D mutant tumors. These observations highlight differences between KRAS mutant cell lines in their signaling properties. Further exploration of these pathways may prove to be valuable for understanding how specific KRAS mutants function, and identification of novel therapeutic opportunities in CRC.
Project description:The goal of this study was to determine genes affected by expressing KRAS mutation (G12V) in NCI-H1703 cells This data was used in Meng Wang et. al. Cancer Research 2016 to determine the alterations of gene expression profiling associated with expression of KRAS mutation (G12V). The experiment uses a pBABE-Puro vector encoding KRAS G12V and a corresponding empty vector control.
Project description:Oncogenic KRAS mutations are prevalent in colorectal cancer (CRC) and are associated with poor prognosis and resistance to therapy. There is a substantial diversity of KRAS mutant alleles observed in CRC. Emerging clinical and experimental analysis of common KRAS mutations suggest that each mutation differently influences the clinical properties of a disease and response to therapy. Although there is some evidence to suggest biological differences between mutant KRAS alleles, these are yet to be fully elucidated. One approach to study allelic variation involves the use of isogenic cell lines that express different endogenous Kras mutants. Here, we generated Kras isogenic Apc-/- mouse colon epithelial cell lines using CRISPR-driven genome editing by altering the original G12D Kras allele to G12V, G12R, or G13D. We utilized these cell lines to perform transcriptomic and proteomic analysis to compare different signaling properties between these mutants. Both screens indicate significant differences in pathways relating to cholesterol and lipid regulation that we validated with targeted metabolomic measurements and isotope tracing. We found that these processes are upregulated in G12V lines through increased expression of nuclear SREBP1 and higher activation of mTORC1. G12V cells showed higher expression of ACSS2 and ACSS2 inhibition sensitized G12V cells to MEK inhibition. Finally, we found that ACSS2 plays a crucial role early in the development of G12V mutant tumors, in contrast to G12D mutant tumors. These observations highlight differences between KRAS mutant cell lines in their signaling properties. Further exploration of these pathways may prove to be valuable for understanding how specific KRAS mutants function, and identification of novel therapeutic opportunities in CRC.
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.