ABSTRACT
Objective To observe the expression difference of lncRNA FAL1 in ovarian cancer cells and their drug-resistant cell lines, and to explore the effect and mechanism of lncRNA FAL1 down-regulation on cell chemotherapy resistance. Methods The expression levels of fal1 gene in SKOV3 and COC1 cells and their drug-resistant cell lines were detected by qRT-PCR. fal1 siRNA was transfected to downregulate fal1 gene expression. MTT was used to detect cell proliferation. Transwell method was used to detect cell invasion ability. Plate clone formation test was used to detect cell clone ability, and Western blot was used to detect MDR-1, mpr-1, ABCG2 and phosphorylation levels of p38 MAPK, ERK1/2 and JNK. SKOV3/DDP and COC1/DDP cells transfected with FAL1-siRNA were injected subcutaneously into BALB/c nude mice. The volume and mass of subcutaneous transplanted tumors were measured. Results Compared with SKOV3 and COC1 cells, SKOV3/DDP and COC1/DDP cells were less sensitive to DDP, and the expression levels of FAL1 gene increased (P < 0.01). After transfection with FAL1-siRNA, the sensitivity of SKOV3/DDP and COC1/DDP cells to DDP increased (P < 0.01), and the invasion (P < 0.05) and cloning ability (P < 0.01) decreased. The expression levels of MDR-1, MPR-1, ABCG2 (P < 0.01) and the phosphorylation levels of p38 MAPK, ERK1/2 and JNK (P < 0.05) decreased. The volume and mass of subcutaneous transplanted tumors were significantly reduced (P < 0.01). Conclusion Down-regulation of lncRNA FAL1 could significantly reduce the chemotherapy resistance of cisplatin-resistant ovarian cancer cell lines and inhibit the proliferation of drug-resistant cells in vivo. Its mechanism is related to inhibiting the activation of MAPK signaling pathway.
ABSTRACT
BACKGROUND: Ovarian cancer is the most frequent cause of death resulting from malignant gynecological tumors. After surgical intervention, cisplatin (DDP) is a major chemotherapy drug for ovarian cancer, but the ovarian cancer cells tend to develop DDP resistance in the clinical setting. Tumor cells are sensitive to low-dose radiation (LDR). However, how the LDR therapy improves the effects of chemotherapy drugs on ovarian cancer is not well understood. This study aimed to explore this issue. METHODS: The SKOV3/DDP cells were divided into 3 groups, including low-dose group, conventional-dose group, and control group (no radiation). Cell counting kit-8 assay was performed to measure cell proliferation. Flow cytometric analysis was then utilized to quantify the apoptosis with classical Annexin V/propidium iodide co-staining. And Real-time quantitative PCR and western blot were eventually used to analyze the mRNA and protein levels of excision repair cross complementing-group 1 (ERCC1), B-cell lymphoma 2 (Bcl-2), Survivin and Caspase-3, respectively. RESULTS: The IC50 value of DDP in the low-dose group was significantly lower compared with the other two groups. Compared with the conventional-dose group and control group, LDR treatment resulted in significantly more apoptosis. Besides, LDR treatment significantly decreased the mRNA and protein expression of ERCC1, Bcl-2, and Survivin, and enhanced the mRNA and protein expression of Caspase-3 compared with the other two groups. CONCLUSIONS: LDR reversed DDP resistance in SKOV3/DDP cells possibly by suppressing ERCC1, Bcl-2, and Survivin expressions, and increasing Caspase-3 expression.