Emerging evidence suggests that miR‐143 plays an important role in the regulation of tumor sensitivity to chemotherapeutic agents. The study explores the underlying mechanism of miR‐143 in reversing cisplatin resistance in ovarian cancer. The cisplatin‐resistant ovarian cancer cell line A2780/CDDP was induced and established via treating A2780 cells by gradually increasing cisplatin concentrations. The IC₅₀ values of A2780/CDDP and A2780 to cisplatin were 218.10 ± 1.12 and 21.99 ± 1.12 μM, respectively. Quantitative real‐time polymerase chain reaction (qRT‐PCR) results showed that miR‐143 was significantly decreased in A2780/CDDP cells compared with A2780 cells. miR‐143 overexpression decreased cisplatin resistance in A2780/CDDP, and miR‐143 inhibition decreased A2780 sensitivity to cisplatin. Results of qRT‐PCR, Western blot analysis, and luciferase reporter assay indicated that the direct target of miR‐143 was DNMT3A, which, in turn, was upregulated in A2780/CDDP. DNMT3A overexpression antagonized the sensitizing effect of miR‐143 on A2780/CDDP to cisplatin. Knocking down of DNMT3A reduced cisplatin resistance in A2780/CDDP, while overexpression of DNMT3A increased cisplatin resistance in A2780. Methylation‐specific polymerase chain reaction results showed that the methylation level in the promoter region of the miR‐143 precursor gene was higher in A2780/CDDP cells than in A2780 cells. DNMT3A mediated the hypermethylation of the miR‐143 precursor gene, resulting in miR‐143 downregulation in A2780/CDDP. miR‐143 inhibited cell growth of A2780/CDDP cell in nude mice. Our findings indicated the negative feedback between miR‐143 and DNMT3A as a crucial epigenetic modifier of cisplatin resistance in ovarian cancer.

中文翻译：

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miR-143和DNMT3A之间的负反馈调节卵巢癌顺铂耐药


新的证据表明 miR-143 在调节肿瘤对化疗药物的敏感性中发挥着重要作用。该研究探讨了 miR-143 逆转卵巢癌顺铂耐药的潜在机制。通过逐渐增加顺铂浓度处理A2780细胞，诱导建立顺铂耐药卵巢癌细胞系A2780/CDDP。 A2780/CDDP和A2780对顺铂的IC ₅₀值分别为218.10±1.12和21.99±1.12μM。实时定量聚合酶链反应（qRT-PCR）结果显示，与 A2780 细胞相比，A2780/CDDP 细胞中 miR-143 显着降低。 miR-143 过表达降低了 A2780/CDDP 的顺铂耐药性，抑制 miR-143 降低了 A2780 对顺铂的敏感性。 qRT-PCR、Western blot 分析和荧光素酶报告基因检测结果表明，miR-143 的直接靶标是 DNMT3A，而 DNMT3A 在 A2780/CDDP 中表达上调。 DNMT3A 过表达拮抗 miR-143 对 A2780/CDDP 对顺铂的敏化作用。 DNMT3A 的敲低降低了 A2780/CDDP 中的顺铂耐药性，而 DNMT3A 的过表达增加了 A2780 中的顺铂耐药性。甲基化特异性聚合酶链反应结果显示，A2780/CDDP细胞中miR-143前体基因启动子区的甲基化水平高于A2780细胞。 DNMT3A 介导 miR-143 前体基因的高甲基化，导致 A2780/CDDP 中 miR-143 下调。 miR-143抑制裸鼠A2780/CDDP细胞的生长。我们的研究结果表明 miR-143 和 DNMT3A 之间的负反馈是卵巢癌顺铂耐药的重要表观遗传修饰因子。