A molecular signature for Epithelial to Mesenchymal transition in a human colon cancer cell system is revealed by large-scale microarray analysis

Abstract

Sporadic colorectal cancer is a major cause of death worldwide. Development takes place in a sequential manner from benign adenomas leading to carcinomas. In 90% of tumours bearing a Ras mutation it is Ki-Ras that is mutated. We have developed a model cell system to study oncogenic Ras mutations in colorectal cancer cell lines. In this analysis two Caco-2 derived cell lines expressing Ha-RasV12 (Caco-H) and Ki-RasV12 (Caco-K), respectively, have been used in large-scale microarray profiling against a Caco-2 control. This was carried out using an Illumina microarray containing 24,000 genes. Genes have been identified as differentially expressed in each isoform as well as commonly regulated. In addition the Caco-H cell line has a strong epithelial-mesenchymal phenotype that is reflected in many of its differentially expressed genes. These include the known EMT markers Vimentin, E-cadherin and Slug. Other genes of interest include several members of the Claudin family, Forkhead transcription factors and GATA-factors. The Caco-K cell line shows strong downregulation of the Dickkopf transcriptional repressor implicating it in WNT signalling. Pathway and functional analysis has also been carried out for the differentially expressed genes for both cell lines using Ingenuity software. This genome wide microarray analysis has provided a molecular signature for EMT in a Caco-H colon cancer cell line. It has also revealed a number of key genes for Caco-K expression and identified novel markers for Ras expression that have been verified by PCR analysis.

Critical role for transcriptional repressor Snail2 in transformation by oncogenic RAS in colorectal carcinoma cells

“…In HKe-3 ER:HRAS V12 cells, RAS pathway activation by adding OHT resulted in a marked reduction in E-cadherin and a scattered cellular phenotype (Figures 3c and d). These results were Snail2 in RAS induced EMT Y Wang et al consistent with a recent microarray analysis in a human colon cancer cell system (Joyce et al, 2009), showing that human colon cancer cells with mutant RAS have a molecular signature for EMT that is reflected in many markers such as E-cadherin and Snail2.…”

Hypoxic and Ras-transformed cells support growth by scavenging unsaturated fatty acids from lysophospholipids

“…A major source of the imported fatty acids are serum lipids with one fatty acid tail, lysolipids. The ability to catabolize lipids with a single fatty acid tail was previously shown to be enhanced in aggressive and Ras-driven cancers (26)(27)(28). The present results show that related scavenging of lysolipids can be a major route of fatty acid acquisition in both hypoxia and Ras-driven cancer cells.…”

“…Intriguingly, the enzyme MG lipase (MAGL), which generates free fatty acids from monoacylglycerols, is highly expressed in aggressive cancer cells and its over-expression enhances tumorigenicity (26). Its expression is also increased by the H-Ras and the K-Ras-HIF pathways (27,28). Although it has been previously hypothesized that the relevance of MAGL to cancer is via enhancing the levels of protumorigenic lipid messengers such as lysophosphatidic acid and PGE 2 , it may also contribute to lysolipid scavenging.…”

L1-Mediated Colon Cancer Cell Metastasis Does Not Require Changes in EMT and Cancer Stem Cell Markers

“…Although L1 expression in CRC cells did not confer an EMT signature, overexpression of Ras in CRC cells was shown to result (by gene expression profiling) in the induction of an EMT-like signature (33,34). Because L1-mediated metastasis in CRC cells requires NF-kB signaling in cells expressing different E-cadherin levels (this study and ref.…”