Chloroquine Enhances Mda-7- Induced Apoptosis via miR-7 and HSP70 Modulation in Glioblastoma

Melanoma differentiation-associated gene-7 (Mda-7) selectively suppresses growth and induces apoptosis in various tumor cells without harming normal cells. Inhibition of autophagy has been shown to enhance the efficacy of many cancer therapies. However, its effect on the anticancer activity of Ad/Mda-7 in GBM has remained unclear. This study investigated the combined effect of an autophagy inhibitor (CQ) and Mda-7 in U87 cancer cells.

Cell proliferation was assessed using the MTT assay. Apoptosis rates, autophagy induction, and ROS levels were measured using flow cytometry. Caspase-9 and β-actin protein levels were analyzed by Western blotting. ELISA was employed to quantify HSP70 and TRAIL level in the culture medium. Real-time PCR evaluated the expression levels of cell death-related genes (P38 MAPK, Bax, and TRAIL) and specific miRNAs (miR-7, miR-122, and miR-21) in treated cells.

Combined treatment with Ad/Mda-7 and the autophagy inhibitor CQ significantly reduced cell viability and proliferation. Ad/Mda-7 induced LC3-II protein expression in U87 cancer cells, which was further increased by autophagy inhibition through CQ. The combination treatment also increased apoptosis rates, elevated ROS levels, and decreased HSP70 protein expression, highlighting its synergistic anticancer effects. Increasing the expression of miR-7 and miR-122 indicated that the elevated levels of these endogenous miRNAs may help improve the treatment process.

Our findings indicate that the combination of Ad/Mda-7 and CQ synergistically could inhibit U87 cancer cell growth and could serve as a promising approach for treating human GBM.