Abstract 3385: Identification of tumor endothelium-related genes in colorectal cancer

Abstract

Abstract Background and Aims: Angiogenesis is a hallmark of cancer development that has been considered an attractive therapeutic target. In this study, we aimed to unravel the molecular mechanism of tumor angiogenesis in colorectal cancer (CRC). Materials and Methods: We isolated endothelial and epithelial cells from surgically resected 14 human CRC tissues by using antibodies against endothelial (CD146) and epithelial markers (EpCAM). RNA sequencing was carried out using 3 pairs of normal and tumor endothelial cells. Expression of the genes was validated using quantitative RT-PCR, immunohistochemistry. Functions of a selected gene were carried analyzed by tumor conditioned medium (TCM) experiments, tube formation assay, gene expression microarray and cell cycle analysis. Results: Through RNA-seq analysis, we identified 18 genes, which were upregulated in the endothelial cells isolated from CRC tissues. We further validated the results by performing quantitative RT-PCR and immunohistochemical analysis in a larger series of clinical samples, and identified gene A as a novel candidate of the tumor endothelium-related gene. Expression of gene A was also upregulated in human umbilical vein endothelial cells (HUVECs) treated with TCM obtained from CRC cell lines. Knockdown of gene A in HUVECs suppressed in vitro tube formation and induced G1 cell cycle arrest. Microarray analysis revealed that gene A knockdown induced expression changes of approximately 300 genes in HUVECs, and gene ontology analysis showed that genes related to cell cycle or cell division were significantly enriched in the affected genes. To confirm our findings in vivo, we co-transplanted CRC cells with HUVECs into nude mice. We found that gene A knockdown in HUVECs resulted in reduced micro vessel formations in the xenograft tissues. Conclusion: We identified elevated expression of gene A in tumor endothelial cells of primary colorectal cancer tissues. Our results suggest that gene A may play an important role in the angiogenesis in colorectal cancer, and that it could be a potential therapeutic target. Citation Format: Akira Yorozu, Eiichiro Yamamoto, Reo Maruyama, Masahiro Kai, Toshihiko Nishidate, Tomohisa Furuhata, Tamotsu Sugai, Hiromu Suzuki. Identification of tumor endothelium-related genes in colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3385.