Abstract 4738: Dysregulated miR-371b-5p/CSDE1/RAC1 axis is involved in pathogenesis of triple-negative breast cancer

Abstract

Abstract Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer; however, pathogenesis of TNBC has not yet been fully understood. Here, we identified dysregulated microRNAs (miRNAs) by analyzing miRNA microarray of TNBC patients. MiR-371b-5p expression was reduced, and ectopic expression of miR-371b-5p significantly inhibited TNBC progression in vitro and in vivo. In addition, we found that expression of cold shock domain-containing protein E1 (CSDE1), a direct target gene of miR-371b-5p, was upregulated in TNBC cells, and inhibition of CSDE1 alleviated TNBC cell growth by decreasing RAC1 known as pro-metastatic gene. Mechanistically, CSDE1, phosphorylated C-terminal domain (p-CTD) of RNA polymerase II (RNAPII), and CDK7 form a complex, and downregulation of CSDE1 results in weak interaction between RNAPII p-CTD and CDK7, which leads to a decrease in RNAPII p-CTD expression to reduce RAC1 transcript levels in CSDE1-deficient TNBC cells. Our data revealed the oncogenic function of miR-371b/CSDE1 involved in Rac1 transcription regulation, thus providing a basis for the pathological mechanism of TNBC along with potential biomarkers for TNBC. Citation Format: Yesol Kim, Je Yeong Ko, Soo-Been Lee, Jaehee Jun, Yejin Ahn, Jinui Min, Chaewon Oh, Jong Hoon Park. Dysregulated miR-371b-5p/CSDE1/RAC1 axis is involved in pathogenesis of triple-negative breast cancer. [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 4738.