We performed a genome-scale CRISPR screen in a KRAS-mutant pancreatic cancer cell line treated with the MEK inhibitor trametinib, and found that loss of the transcriptional repressor CIC confers resistance to MEK inhibition. We determined that CIC loss also confers resistance to MEK or BRAF inhibition in lung cancer, colorectal cancer, and melanoma cell lines with mutant RAS or BRAF. CIC is a transcriptional repressor that is phosphorylated and inhibited by the MAPK pathway. We hypothesized that inhibition of the MAPK pathway would lead to activation of CIC and repression of CIC target genes. Loss of CIC would therefore restore expression of these genes, conferring drug resistance. To identify the relevant CIC target genes that mediate trametinib resistace, we generated 4 Cas9-expressing cell lines from different lineages and with different RAS or RAF mutations, and generated control (gGFP) or CIC-knockout (gCIC) cell lines. We treated cells with DMSO or trametinib for 24 hours, and performed NRA-seq. We found that trametinib treatment reduces expression of at least one member of the PEA3 family of ETS transcription factors (ETV1, ETV4, and ETV5) in all cell lines assessed, and that loss of CIC results in maintained expression of these genes despite MEK inhibition. We further validated that ETV1, 4, and 5 expression was necessary for resistance mediated by CIC loss; and that ETV1, 4, or 5 expression was sufficient to confer trametinib resistance. Overall design: 4 Cas9-expressing human cancer cell lines (A549, CALU1, HCT116, PATU8902) were used to generate 3 isogenic cell lines with intact CIC (gGFP-1) or knocked out CIC (gCIC-1 or gCIC-2). Each of these 12 cell lines were treated with DMSO or trametinib for 24 hours (duplicates)
ATXN1L, CIC, and ETS Transcription Factors Modulate Sensitivity to MAPK Pathway Inhibition.
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View SamplesCancer 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.
KRAS and YAP1 converge to regulate EMT and tumor survival.
Cell line
View SamplesCancer 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 Overall design: 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.
KRAS and YAP1 converge to regulate EMT and tumor survival.
No sample metadata fields
View SamplesDifferentiation events contribute to cellular heterogeneity within tumors and influence disease progression and response to therapy. Here we dissect the mechanisms controlling intratumoral heterogeneity within basal-like breast cancers. We show that cancer cells can transition between a differentiation state related to that of normal luminal progenitors and a state closer to that of mature luminal cells, and that this occurs through asymmetric cell divisions. The Polycomb factor EZH2 and the Notch pathway act to increase the rates of symmetric divisions that produce progenitor-like cells, while the FOXA1 transcription factor promotes asymmetric divisions that reduce the numbers of such cells. Through functional screening, we identified a group of regulators that control cancer cell differentiation state and the relative proportions of tumor cell subpopulations. Our findings highlight the regulation of asymmetric cell divisions as a mechanism controlling intratumoral heterogeneity, and identify molecular pathways that control breast cancer cellular composition. Overall design: Expression profiles of HCC70 cells expressing shRNAs targeting regulatory factors that influence basal-like cancer cell population composition
Regulation of Cellular Heterogeneity and Rates of Symmetric and Asymmetric Divisions in Triple-Negative Breast Cancer.
Cell line, Subject
View SamplesDifferentiation events contribute to cellular heterogeneity within tumors and influence disease progression and response to therapy. Here we dissect the mechanisms controlling intratumoral heterogeneity within basal-like breast cancers. We show that cancer cells can transition between a differentiation state related to that of normal luminal progenitors and a state closer to that of mature luminal cells, and that this occurs through asymmetric cell divisions. The Polycomb factor EZH2 and the Notch pathway act to increase the rates of symmetric divisions that produce progenitor-like cells, while the FOXA1 transcription factor promotes asymmetric divisions that reduce the numbers of such cells. Through functional screening, we identified a group of regulators that control cancer cell differentiation state and the relative proportions of tumor cell subpopulations. Our findings highlight the regulation of asymmetric cell divisions as a mechanism controlling intratumoral heterogeneity, and identify molecular pathways that control breast cancer cellular composition. Overall design: Expression profiles of three cell subpopulations – K18+, K18+K14+ and K18+Vim+ – sorted from the breast cancer cell lines HCC70 and MDA-MB-468
Regulation of Cellular Heterogeneity and Rates of Symmetric and Asymmetric Divisions in Triple-Negative Breast Cancer.
Cell line, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Integrated approaches to miRNAs target definition: time-series analysis in an osteosarcoma differentiative model.
Specimen part, Cell line, Time
View SamplesWe explored the transcriptional modification induced by CD99 transfection in the osteosarcoma cell lines SaOS-2 after 0, 7 and 14 days in differentiation medium.
Integrated approaches to miRNAs target definition: time-series analysis in an osteosarcoma differentiative model.
Specimen part, Cell line, Time
View SamplesThis SuperSeries is composed of the SubSeries listed below.
An epigenetic mechanism mediates developmental nicotine effects on neuronal structure and behavior.
Age, Specimen part
View SamplesDevelopmental nicotine exposure causes persistent changes in cortical neuron morphology and in behavior.
An epigenetic mechanism mediates developmental nicotine effects on neuronal structure and behavior.
Age, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
An epigenetic mechanism of resistance to targeted therapy in T cell acute lymphoblastic leukemia.
Specimen part, Cell line
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