KLF5-trancripted miR-125b-5p is involved in enhancing the radio-sensitivity of breast cancer cells by targeting BRCA1

Background A large number of clinical trials have proved that radiotherapy is an effective strategy for treating breast cancer (BC), but radioresistance is an urgent problem to be solved. Objective Herein, radio-tolerant BC cell lines named MDA-MB-231/R and MCF-7/R were successfully constructed, respectively, and it was shown that microRNA-125b-5p (miR-125b-5p) was lowly expressed in radio-tolerant cells, which was associated with poor prognosis of BC patients. Results Furthermore, miR-125b-5p over expression could hinder cell proliferation and strengthen radio-sensitivity. Mechanistically, Breast Cancer 1 (BRCA1) was identified as a downstream protein target of miR-125b-5p in BC cells, and Kruppel-like factor 5 (KLF5) was identified as an upstream transcription factor involved in promoting miR-125b-5p expression. More importantly, over expression of KLF5 suppressed BC cell proliferation and increased its radiation sensitivity, which could be retained by miR-125b-5p downregulation. Conclusion In conclusion, these findings suggested that the KLF5/miR-125b-5p/BRCA1 axis may provide new information on radiation therapy for breast cancer.