Abstract 817: microRNA-26a-5p is a prognostic factor that regulates cancer stemness

Abstract Background: Cancer stem cells (CSCs) identified in lung cancer exhibit resistance to chemotherapy, radiotherapy, and targeted therapy. Therefore, a technology to control of CSCs is needed to overcome such resistance to cancer therapy. Various evidences about the association between epithelial-mesenchymal transition related transcriptomic alteration and acquisition of CSC phenotype have been proposed recently. In our previous research, down-regulated miR-26a-5p is closely related to mesenchymal-like lung cancer cell lines. These findings suggest that miR-26a-5p might be involved in lung cancer stemness. Methods: RNA polymerase III subunit G (POLR3G) was selected as a candidate target of miR-26a-5p related to cancer stemness. its quantitative relationship was investigated by polymerase chain reaction, western blot after transfection of miR-26a-5p. luciferase assay were done for investigating the direct regulation of miR-26a-5p on POLR3G expression. After transfection of miR-26a-5p, colony formation assay and sphere formation assay were performed to evaluate the effect on cancer stemness. By treating cancer cell by miR-26a-5p and paclitaxel, cell viability was checked by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and Muse cell analyzer. Expression level of each gene and its impact on survival were revealed by the cancer genome atlas pancancer database. Results: miR-26a-5p regulated the expression of POLR3G directly. Overexpression of miR-26a-5p induced down regulation of POLR3G and a marked reduction of colony formation and sphere formation. Co-treatment of miR-26a-5p with paclitaxel decreased cell growth, suggesting that miR-26a-5p might play a role as a chemotherapy sensitizer. In the cancer genome atlas data, down-regulated miR-26a-5p and up-regulated POLR3G were shown compared to adjacent normal tissue. High miR-26a-5p and low POLR3G expression were also related to higher survival rate of patients with lung adenocarcinoma. Conclusions: Overexpression of miR-26a-5p can suppress lung cancer stemness and make cancer cell become sensitive to chemotherapy. This finding provides a novel insight into a potential lung cancer treatment by regulating stemness. Citation Format: Daeun Kang, Chang Ryul Park, Minhyeok Lee, Su Yel Lee, Se Jin Park, Wan Jin Hwang, Gwan Woo Ku, Seong Lan Yu, In Beom Jeong, Sun Jung Kwon, Jaeku Kang, Eung Bae Lee, Ji Woong Son. microRNA-26a-5p is a prognostic factor that regulates cancer stemness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 817.