Metformin Affects Paclitaxel Sensitivity of Ovarian Cancer Cells Through Autophagy Mediated by Long Noncoding RNASNHG7/miR-3127-5p Axis

Background: Ovarian cancer is the public health issue worldwide. Paclitaxel is a first-line chemotherapy drug for ovarian cancer, but paclitaxel resistance weakens the therapeutic effect. Metformin (Met) improved the paclitaxel sensitivity in a mouse model of ovarian cancer. However, the mechanism of Met on paclitaxel sensitivity is still unclear in ovarian cancer. Materials and Methods: Cell viability, apoptosis, migration, and invasion were measured by Cell Counting Kit-8 (CCK8), flow cytometry, and transwell assays severally. The expression of long noncoding RNA (lncRNA) small nucleolar RNA host gene 7 (SNHG7) and microRNA-3127-5p (miR-3127-5p) were detected by real-time quantitative polymerase chain reaction. The protein levels of poly (ADP-ribose) polymerase, microtubule-associated protein 1 light chain 3 (LC3)-I, LC3-II, and Beclin 1 were examined by Western blot assay. RNA immunoprecipitation assay detected the relationship between SNHG7 and miR-3127-5p. Then, the binding correlation between SNHG7 and miR-3127-5p was predicted by starBase and verified by the dual-luciferase reporter. The effects of Met and SNHG7 on tumor growth were tested in ovarian cancer mice model. Results: Met inhibited cell viability, migration, invasion, SNHG7 level, and autophagy and promoted apoptosis in paclitaxel-resistant ovarian cancer cells. Moreover, Met partly reversed SNHG7-mediated paclitaxel sensitivity and autophagy in ovarian cancer cells. SNHG7 directly bound to miR-3127-5p. Met abolished the promoting effect of SNHG7 overexpression on tumor growth and autophagy in vivo. Conclusion: The authors' findings indicated that Met expedited paclitaxel sensitivity by regulating SNHG7/miR-3127-5p-mediated autophagy in ovarian cancer cells.