Abstract 3599: Molecular characterization of mouse colorectal cancer cell lines with high potential of peritoneal metastasis
Authors: Mori Haruki , Isomura Hisanori , Zhou Shuang , Kajino Taisuke , Abe Yuichi , Kinoshita Takashi , Natsume Seiji , Sato Yusuke , Ouchi Akira , Miyake Toru , Hosoda Waki , Komori Koji , Shimizu Yasuhiro , Tani Masaji , Taguchi Ayumu 
Published: April 2023

Abstract
Background: Peritoneal metastasis occurs in approximately 7% of colorectal cancer (CRC) patients and is associated with worse prognosis compared to non-peritoneal metastasis. In CRC patients with peritoneal metastasis, administration of systemic chemotherapy only slightly improves overall survival. Therefore, a better understanding of the biology of peritoneal metastasis and the development of new molecular therapeutics for CRC patients with peritoneal metastasis are urgently needed.
Materials and Methods: CT26 mouse CRC cell lines with low metastatic potentials (CT26-N5) and high metastatic potentials to peritoneum (CT26-P6) were established after several rounds of in vivo selection by orthotopic transplantation of CT26 cells into the syngeneic BALB/c mice. Transcriptomic and proteomic analyses were conducted on CT26-N5 and CT26-P6 cells.
Results: Orthotopic transplantation of CT26-P6 cells exhibited significantly increased peritoneal metastasis compared to CT26-N5 cells, while growth of primary tumors was not different between these CT26 sublines. In addition, CT26-P6 cells had higher cell migration and invasion potential in vitro than CT26-N5 cells. Integrated analyses of transcriptome and proteome resulted in identification of molecular signatures associated with peritoneal metastasis. An actin-binding protein Advillin, encoded by the Avil gene, was markedly increased at both mRNA and protein levels in CT26-P6 cells compared to CT26-N5 cells. Knockdown of Avil using siRNA or shRNA in CT26-P6 cells significantly reduced cell migration and invasion in vitro and occurrence of peritoneal metastasis in vivo. Gene Set Enrichment Analysis on transcriptome datasets from CT26-P6 cells and CT26-N5 cells identified interferon gamma response as the most significantly enriched pathway in CT26-cells. In addition, Immunoprecipitation coupled with LC-MS/MS identified potential interaction between Avil and a molecule X that regulates epithelial-mesenchymal transition in CRC. Consistent with the findings in mouse CT26 cells, AVIL knockdown in CRC patient-derived cells (PDCs) suppressed cell migration and invasion in vitro. While AVIL expression was induced by interferon gamma in CRC PDCs, JAK inhibitors, Momelotinib and Ruxolitinib, significantly reduced interferon gamma-induced AVIL expression, suggesting regulation of AVIL by interferon gamma.
Conclusion: Molecular characterization of mouse colorectal cancer cell lines with different metastatic potential identified AVIL as a potential therapeutic target in CRC patients with peritoneal metastasis. Regulation of AVIL expression by interferon gamma may suggest functional relevance of tumor immune microenvironment in the development of peritoneal metastasis in CRC.
Citation Format: Haruki Mori, Hisanori Isomura, Shuang Zhou, Taisuke Kajino, Yuichi Abe, Takashi Kinoshita, Seiji Natsume, Yusuke Sato, Akira Ouchi, Toru Miyake, Waki Hosoda, Koji Komori, Yasuhiro Shimizu, Masaji Tani, Ayumu Taguchi. Molecular characterization of mouse colorectal cancer cell lines with high potential of peritoneal metastasis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3599.