This SuperSeries is composed of the SubSeries listed below.
PI3K-targeted therapy can be evaded by gene amplification along the MYC-eukaryotic translation initiation factor 4E (eIF4E) axis.
Specimen part
View SamplesGene expression signatures were measured after treatment of cells with 50nM BEZ235. Affymetrix HG-U133AV2 expression arrays were performed according to the manufacturer's directions using RNA extracted by Qiagen RNeasy from engineered human cell-lines grown for 72h in the presence of 50nM BEZ235
PI3K-targeted therapy can be evaded by gene amplification along the MYC-eukaryotic translation initiation factor 4E (eIF4E) axis.
Specimen part
View SamplesGene expression (mRNA profiling) of U2OS osteosarcoma cells treated with 1 mM of the CDK4/6-specific inhibitor, PD0332991, versus vehicle (DMSO) for 4 hours
A systematic screen for CDK4/6 substrates links FOXM1 phosphorylation to senescence suppression in cancer cells.
Specimen part, Cell line, Treatment
View SamplesPGC1a is a transcriptional coactivator that regulates energy metabolism. PGC1a is highly expressed in a subset of melanoma tumors and cell lines. We generated gene-expression profile of control and PGC1alpha depleted A375P melanoma cells, a melanoma cell line that expresses very high levels of PGC1a to investigate the role of this gene in melanoma.
PGC1α expression defines a subset of human melanoma tumors with increased mitochondrial capacity and resistance to oxidative stress.
Specimen part
View SamplesMelanoma growth is driven by malignant melanoma initiating cells (MMIC) identified by expression of the ATP-binding cassette (ABC) member, ABCB5. ABCB5+ melanoma subpopulations have been shown to overexpress the vasculogenic differentiation markers CD144 (VE-cadherin) and TIE-1 and are associated with CD31-negative vasculogenic mimicry (VM), an established biomarker associated with increased patient mortality. Here we identify a critical role for VEGFR-1 signaling in ABCB5+ MMIC-dependent VM and tumor growth. Global gene expression analyses, validated by mRNA and protein determinations, revealed preferential expression of VEGFR-1 on ABCB5+ tumor cells purified from clinical melanomas and established melanoma lines. In vitro, VEGF induced in a VEGFR-1-dependent manner expression of CD144 in ABCB5+ subpopulations that constitutively expressed VEGFR-1, but not in ABCB5- bulk populations that were predominantly VEGFR-1-negative. In vivo, melanomaspecific shRNA-mediated knockdown of VEGFR-1 blocked the development of ABCB5+ VM morphology and inhibited ABCB5+ VM-associated production of the secreted melanoma mitogen, laminin. Moreover, melanoma-specific VEGFR-1 knockdown markedly inhibited tumor growth (by >90%). Our results demonstrate that VEGFR-1 function in MMIC regulates VM and associated laminin production, and show that this function represents one mechanism through which MMIC promote tumor growth.
VEGFR-1 expressed by malignant melanoma-initiating cells is required for tumor growth.
Specimen part
View SamplesWe 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 SamplesGene expression signatures were measured in logarithmic growing cultures
Oncogenic BRAF regulates oxidative metabolism via PGC1α and MITF.
Specimen part
View SamplesExtracellular, cancer-specific methylated DNA has been shown to be a prognostic marker when detected in serum or plasma. In this study we investigated the effect of treating cancer cells with differentially methylated CpG DNA. When breast cancer cell lines were treated with methylated CpG DNA, a consistent upregulation of CHAC1 mRNA expression was observed. CHAC1 was recently described to be a novel component of the unfolded protein response pathway. To elucidate the role of CHAC1 mRNA expression in cancer in more detail, we analyzed expression of this gene in breast (n=107) and ovarian cancer (n=107) and found a strong correlation with tumor differentiation. Poorly differentiated tumors exhibited higher CHAC1 expression levels (p=0.004 for breast and p=0.031 for ovarian cancer). Additionally, hormone receptor (HR)-negative breast cancers (p<0.001) and advanced stage disease ovarian cancers (p=0.026) also demonstrated high CHAC1 mRNA levels. mRNA expression analysis of the two known CHAC1 isoforms showed a strong association of expression above the median with poor outcome in breast cancer patients in a multivariate analysis (isoform a: relative risk (RR) of death 3.2 (95% CI 1.6-6.5; p<0.01); RR of relapse 3.9 (95% CI 1.6-9.8; p<0.01); isoform b: relative risk (RR) of death 3.5 (95% CI 1.6-7.3; p<0.01); RR of relapse 6.6 (95% CI 2.4-18.5; p<0.01)). Univariate analysis in ovarian cancer showed that CHAC1 mRNA expression above the median was associated with a poor relapse free survival (p=0.03). In younger ovarian cancer patients (age < median age), a high CHAC1 mRNA expression was associated with overall survival (p=0.007) and relapse free survival (p=0.015). Finally, we show that downregulation of CHAC1 by small interfering RNA suppressed breast cancer cell migration and proliferation, whereas overexpression resulted in an observed increase in these cellular behaviours. This is the first report demonstrating that a gene (CHAC1) whose expression is triggered by methylated, but not unmethylated DNA, is involved in tumour biology.
Elevated mRNA expression of CHAC1 splicing variants is associated with poor outcome for breast and ovarian cancer patients.
Specimen part, Cell line, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
BRAFV600E-Associated Gene Expression Profile: Early Changes in the Transcriptome, Based on a Transgenic Mouse Model of Papillary Thyroid Carcinoma.
Sex, Age
View SamplesBRAFV600E mutation is the most frequent molecular event in papillary thyroid carcinoma. The relation of this genetic alteration with the factors od poor prognosis has been reported as well as its influence on PTC gene signature. However human material disables distinction of cancer causes from its effect.
BRAFV600E-Associated Gene Expression Profile: Early Changes in the Transcriptome, Based on a Transgenic Mouse Model of Papillary Thyroid Carcinoma.
Sex, Age
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