Abstract 1535: Identification of novel epithelial-mesenchymal transition inducers and their clinical significance in colorectal cancer

Abstract

Abstract Purpose. Cancer tissues contain a substantial amount of stromal tissues, and transcriptome derived from bulk samples originates from a mixture of the cancer epithelium and stroma. Gene signature of epithelial-mesenchymal transition (EMT) cells is similar to that of stromal cells; therefore, gene signature that we considered to be related EMT might be only contamination of stroma. Here, we identify novel EMT inducers by analysis of independent gene expression profiles in the colorectal cancer epithelium and stroma. Materials and Methods. Gene expression data of pure epithelial tissue was obtained using laser microdissection technique from 13 colorectal cancer tissues. Next, the ratio of each gene expression in the stroma to in the epithelium and correlation of each gene expression with a target gene derived from The Cancer Genome Atlas (TCGA) is plotted in two dimensions, and correlation coefficients are calculated. We regard genes with high correlation coefficients but highly expressed in the epithelium as candidates of EMT inducers. We manipulate the expression of some candidate genes in colorectal cancer cell lines to investigate the alterations of EMT markers and migration ability in vitro. Results. We extract 91 new putative EMT-related genes in silico. They are highly expressed in similar cell lines to known EMT markers in a public database. Furthermore, some candidates have reported having a relation to EMT, and that indicates the validity of this procedure. The knockdown of three candidate genes upregulates epithelial gene expression and downregulates mesenchymal gene expression. The knockdown of one of the three genes reduces cell migration. In contrast, overexpression of the gene downregulates epithelial gene expression and leads to cell migration. Conclusion. We identify novel EMT inducers successfully using purified gene expression data. They could be new prognostic markers and therapeutic targets of colorectal cancer. Citation Format: Satoshi Ishikawa, Naohiro Nishida, Shiki Fujino, Takayuki Ogino, Hidekazu Takahashi, Norikatsu Miyoshi, Mamoru Uemura, Chu Matsuda, Tsunekazu Mizusima, Hirofumi Yamamoto, Koshi Mimori, Masaki Mori, Yuichiro Doki, Hidedoshi Eguchi. Identification of novel epithelial-mesenchymal transition inducers and their clinical significance in colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1535.