Project description:Type I low-grade gliomas (LGGs), characterized by 1p/19q co-deletions and IDH1/2 mutations, show superior overall survival compared to other gliomas. Approximately 70% of cases harbour mutations in the Capicua (CIC) gene, whose product is a transcriptional repressor whose transcriptional network has yet to be extensively studied in human cells. To address this, we developed CIC knockout cell lines and used transcriptome analyses to study the consequences of CIC loss. Results were further compared to data for Type I LGGs and stomach adenocarcinomas from The Cancer Genome Atlas (TCGA). We find that CIC appears to regulate the expression of genes involved in cell-cell adhesion and nervous system development. CIC deficiency is also found to be associated with a MEK activation transcriptional signature and to act as an effector of MEK signalling. Loss of CIC may thus present a novel mechanism for the dysregulation of this and other oncogenic pathways.
Project description:CIC encodes a transcriptional repressor inactivated by loss-of-function mutations in several cancer types, indicating that it may function as a tumor suppressor. Recent data indicate that CIC may regulate cell cycle genes in humans; however, a thorough investigation of this proposed role has not yet been reported. Here, we used single-cell RNA sequencing technology to provide evidence that inactivation of CIC in human cell lines resulted in transcriptional dysregulation of genes involved in cell cycle control. We also mapped CIC’s protein-protein and genetic interaction networks, identifying interactions between CIC and members of the Switch/Sucrose Non-Fermenting (SWI/SNF) complex, as well as novel candidate interactions between CIC and cell cycle regulators. We further showed that CIC loss was associated with an increased frequency of mitotic defects in human cell lines and a mouse model. Overall, our study positions CIC as a cell cycle regulator and indicates that CIC loss can lead to mitotic errors, consistent with CIC’s emerging role as a tumor suppressor of relevance in several cancer contexts.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:We identified genome-wide binding patterns of CIC in several different cell types and find that CIC target genes are enriched for MAPK effector genes involved in cell cycle regulation and proliferation. CIC binding to its target genes is abolished by high MAPK activity, which leads to hyperacetylation and their transcriptional activation. Inhibition of MAPK signaling via MEK inhibition leads to recruitment of CIC to its target genes. Expression data of G144 cells after MEK inhibition and CIC knockout is available under accession E-MTAB-6681
Project description: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.