Objective  To investigate the effect of microRNA-214-3p (miR-214-3p) expression in cancer-associated fibroblasts (CAFs) on the cisplatin sensitivity of ovarian cancer cells and its mechanism.

Methods  Sixty-four ovarian cancer patients were selected as study subjects and divided into platinum-partially sensitive group and platinum-sensitive group based on progression-free survival after chemotherapy. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to detect the relative expression of miR-214-3p in ovarian cancer tissues from the two groups, and the 2-year survival rates of patients with different clinical characteristics were compared. CAFs and normal ovarian fibroblasts (NFs) were primarily cultured, and qRT-PCR and immunofluorescence experiments were used to detect the expression of miR-214-3p and p62 protein in CAFs and NFs. The expression levels of SQSTM1 gene in different types of ovarian cells were searched through the CSIOVDB database. CAFs were transiently transfected with miR-214-3p mimic (mimic group) and miR-214-3p mimic NC (NC group), and untransfected CAFs were selected as control group. Cell culture supernatants from each group were collected, and an indirect co-culture model of ovarian cancer cell line SKOV3 with CAFs from each group was established. The CCK-8 method, DCFH-DA method, qRT-PCR, and immunoblotting were used to detect the proliferation rate, half-maximal inhibitory concentration of cisplatin (IC50), reactive oxygen species (ROS) content, and relative expression levels of miR-214-3p, cisplatin resistance gene CCND1, and autophagy protein p62 in SKOV3 cells under different culture conditions.

Results  The relative expression of miR-214-3p was lower in the platinum-partially sensitive group than in the platinum-sensitive group (P < 0.01). There were statistically significant differences in the 2-year survival rates among patients with different International Federation of Gynecology and Obstetrics (FIGO) stages, platinum partial sensitivity, and low miR-214-3p expression (P < 0.01). The relative expression of miR-214-3p was lower in ovarian CAFs than in NFs, while the expression level of p62 protein was higher in CAFs than in NFs (P < 0.01). Online analysis of the CSIOVDB database showed that the expression level of SQSTM1 gene in ovarian CAFs was higher than that in ovarian cancer epithelial cells and NFs (P < 0.01). Compared with SKOV3 cells indirectly co-cultured with CAFs in the control group and CAFs in NC group, SKOV3 cells indirectly co-cultured with mimic CAFs showed reduced proliferation rate, cisplatin IC50, and ROS content, increased relative expression of miR-214-3p, and decreased relative expression of CCND1 mRNA and p62 protein (P < 0.01).

Conclusion  The expression of miR-214-3p in CAFs is correlated with the sensitivity of ovarian cancer cells to cisplatin. Low expression of miR-214-3p in CAFs can promote the proliferation of ovarian cancer cells and ROS-mediated autophagy, thereby reducing the sensitivity of ovarian cancer cells to cisplatin.