Le Zhao

The negative feedback between miR‐143 and DNMT3A regulates cisplatin resistance in ovarian cancer

AbstractEmerging 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.

Ginsenoside 20(S)‐Rg3 upregulates HIF‐1α‐targeting miR‐519a‐5p to inhibit the Warburg effect in ovarian cancer cells

Abstract The Warburg effect, one of the metabolic hallmarks of cancer, is responsible for rapid energy production through a high rate of aerobic glycolysis. Ginsenoside 20(S)‐Rg3 antagonizes the Warburg effect in ovarian cancer cells by upregulating some microRNAs, including miR‐519a‐5p, that target key enzymes involved in aerobic glycolysis. How 20(S)‐Rg3‐upregulated miR‐519a‐5p influences the Warburg effect in ovarian cancer cells remains poorly defined, however. Here we report that while overexpression of miR‐519a‐5p in ovarian cancer cells inhibited the Warburg effect, inhibition of miR‐519a‐5p negated the suppressive action of 20(S)‐Rg3 against the Warburg effect as evidenced by a decrease in glucose consumption, lactate production and HK2 expression. We identified HIF‐1α as a direct target of miR‐519a‐5p via luciferase reporter assays and demonstrated the counteraction by overexpressed HIF‐1α of 20(S)‐Rg3‐suppressed Warburg effect. Further, 20(S)‐Rg3 decreased DNMT3A‐mediated DNA methylation in the promoter region of its precursor gene, leading to an increase in the level of miR‐519a‐5p. In conclusion, 20(S)‐Rg3 upregulates miR‐519a‐5p via reducing DNMT3A‐mediated DNA methylation to inhibit HIF‐1α‐stimulated Warburg effect in ovarian cancer.

Tumor-suppressive SQLE reprograms metabolic flux: Convergence of aerobic glycolysis and cholesterol pathways in ovarian cancer

Squalene epoxidase (SQLE) exerts anti-ovarian cancer (OC) role, but its mechanistic basis remains to be defined. Through integrated bioinformatic analysis and immunohistochemistry, SQLE protein expression was found highly expressed in OC tissue compared to normal ovarian tissue, however, using the stable/transient SQLE knockdown and overexpression OC cell models, the cell proliferation and metabolism assays revealed SQLE knockdown enhanced, while SQLE overexpression suppressed cell proliferation, total/free cholesterol level, glycolytic flux and hexokinase Ⅱ (HK2) expression. SQLE positively regulated farnesyl-diphosphate farnesyltransferase 1 (FDFT1) expression. These results showed SQLE reprogramed cellular cholesterol homeostasis and aerobic glycolytic metabolism, and exerted tumor-suppressive effects in OC cells, providing a new insight for OC treatment.