MiR-7-5p suppresses stemness and enhances temozolomide sensitivity of drug-resistant glioblastoma cells by targeting Yin Yang 1.

Glioblastoma multiforme (GBM) is the most malignant tumor of the central nervous system, and chemoresistance blunts the effect of temozolomide (TMZ) in the treatment of GBM. Clarifying the underlying mechanism of chemoresistance might yield novel strategies to improve the patients' response to chemotherapeutics. Mounting evidence indicates that microRNAs (miRNAs) are involved in chemoresistance and tumorigenesis. At present, miR-7-5p has been recognized as a tumor suppressor involved in multiple cancers. However, the biological effects of miR-7-5p in TMZ resistance have not been illuminated. In this study, we used RNA sequencing and high-throughput screening techniques, which revealed that miR-7-5p is significantly downregulated in TMZ resistant LN229 cells (LN229/TMZ-R) compared to control cells (LN229), and low miR-7-5p expression was correlated with recurrence in GBM patients. Ectopic overexpression of miR-7-5p sensitized LN229/TMZ-R cells to TMZ and suppressed the stemness of glioblastoma stem cells (GSCs). Further experiments demonstrated that miR-7-5p exerts its role by directly targeting the 3'-untranslated region of Yin Yang 1 (YY1). Our findings suggest that combinational use of miR-7-5p and TMZ might be a promising therapeutic strategy to increase the long-term drug response in GBM patients.