Abstract 1879: Transcriptional regulation of KAI1 by p73 in colorectal cancer metastasis

Abstract

Abstract Background: p73 is a member of the p53 family transcription factors and known tumor suppressor. However, its transcriptional activity is complex owing to its multiple isoforms, and limited information is available regarding the transcriptional and functional regulation of the p73 gene in colorectal cancer. In this study, we examined the role of p73 in colorectal cancer. Methods: We established a TAp73 overexpressing cell line using the Tet-on inducible expression system and analyzed global RNA expression by RNA-sequencing (RNA-seq). We studied the effects of TAp73 expression on the migration, invasiveness, and EMT of colon cancer cells. We conducted experiments in animals with liver metastasis of colorectal cancer. To investigate the roles of p73 in colon cancer, we examined the samples from patients, who had undergone surgical resection for colorectal cancer between 2009 and 2013. mRNA expression of TAp73 and KAI1 was analyzed in 108 colorectal cancer specimen and adjacent non-cancerous tissues by real-time RT-PCR. Results: RNA-seq showed the association between TAp73 and KAI1 expression. Migration and invasiveness of colon cancer cells were reduced by TAp73 expression, but induced by KAI1 knockdown. TAp73 regulates KAI1 expression in colon cancer cell lines. TAp73-induced decrease in invasiveness and epithelial-mesenchymal transition (EMT) was abrogated by KAI1 knockdown in TAp73 overexpressing cells. Migration ability of TAp73 overexpressing cells was recovered by KAI1 knockdown. Hepatic metastases were significantly reduced in mice injected with TAp73 overexpressing cells and increased in those injected with TAp73 overexpressing cells with KAI1 knockdown. mRNA expression of TAp73 and KAI1 was higher in colorectal cancer tissues than in adjacent non-cancerous tissues. Significant correlation between TAp73 and KAI1 mRNA expression was detected in early stage primary colorectal cancer, but not in the advanced stage. Conclusions: This study suggests that p73 (TAp73) acts as a tumor suppressor in the progression of colorectal cancer and regulates the expression of KAI1, which is a key target of p73 in colorectal cancer liver metastases. Note: This abstract was not presented at the meeting. Citation Format: Woo Kyun Bae, Kyung Hyun Yoo, Keunsoo Kang, Lothar Hennighausen, Ik-Joo Chung. Transcriptional regulation of KAI1 by p73 in colorectal cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1879. doi:10.1158/1538-7445.AM2017-1879