Background: Chronic inflammation and an inflammatory cytokine, interleukin(IL)-6, play important roles in gastrointestinal tumorigenesis and metastasis. Recently, autocrine IL-6 has been reported to promote cancer development and progression in gastrointestinal cancer. However, it is still unknown how IL-6 level is regulated in gastrointestinal cancer cells. RNA-binding proteins (RBPs) are known to be one of the regulatory mechanisms of cytokine production, including IL-6, especially in immune cells. AT rich interaction domain 5a (Arid5a), one of the RBPs, has been reported to bind to IL6 3’UTR and regulates its stability and expression. Therefore, we aimed to elucidate the role of Arid5a in gastrointestinal cancer, especially gastric and colon cancer.

Methods: Human gastric and colon cancer cell lines were used in this study. Arid5a knocked-down gastric and colon cancer cells were generated with lentiviral transduction of shRNAs targeting Arid5a and their phenotypes were investigated by several assays including MTT, apoptosis and sphere formation assays. Bulk RNA-seq analysis was performed using Arid5a knocked-down gastric and colon cancer cells.

Results: In both human gastric and colon cancer cell lines, Arid5a knockdown suppressed cancer cell proliferation and spheroid formation, and increased apoptosis. Unexpectedly, IL6 mRNA expression was not correlated with Arid5a expression level. We found that Arid5a knockdown suppresses the activation of YAP and STAT3 by western blot analysis. We identified several new Arid5a target genes by bulk RNA-seq analysis.

Conclusion: Arid5a plays an important role in the regulation of cancer cell proliferation, apoptosis and stemness in human gastric and colon cancer cells, perhaps independently of IL-6. Arid5a regulates YAP and STAT3 pathways by unknown mechanisms. We are now investigating how Arid5a regulates YAP and STAT3 pathways by focusing new Arid5a target genes.

Citation Format: Koji Taniguchi, Kazuya Hamada, Shugo Tanaka, Hiroyuki Kurosu, Issei Kawakita, Kentaro Kumagai, Kentaro Nakazono, Sari Iwasaki, Satoshi Tanaka. AT rich interaction domain 5a promotes gastrointestinal tumorigenesis by regulating YAP and STAT3 pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4377.