The high mortality rate of ovarian cancer is connected with the development of acquired resistance to multiple cancer drugs, especially cisplatin. Activation of cytoprotective autophagy has been implicated as a contributing mechanism for acquired cisplatin resistance in ovarian cancer cells. Hexokinase 2 (HK2) phosphorylates glucose to generate glucose-6-phosphate, the rate-limiting step in glycolysis. Higher HK2 expression has been associated with chemoresistance in ovarian cancer. However, whether HK2 functionally contributes to cisplatin resistance in ovarian cancer is unclear. In this study, we investigated the role of HK2 in regulating ovarian cancer cisplatin resistance. Increased HK2 levels were detected in drug-resistant human ovarian cancer cells and tissues. Cisplatin downregulated HK2 in cisplatin-sensitive but not in resistant ovarian cancer cells. HK2 knockdown sensitized resistant ovarian cancer cells to cisplatin-induced cell death and apoptosis. Conversely, HK2 overexpression in cisplatin-sensitive cells induced cisplatin resistance. Mechanistically, cisplatin increased ERK1/2 phosphorylation as well as autophagic activity. Blocking autophagy with the autophagy inhibitor 3-MA sensitized resistant ovarian cancer cells to cisplatin. HK2 overexpression enhanced cisplatin-induced ERK1/2 phosphorylation and autophagy while HK2 knockdown showed the opposite effects. Blocking the MEK/ERK pathway using the MEK inhibitor U0126 prevented cisplatin-induced autophagy enhanced by HK2 overexpression. Furthermore, HK2 knockdown sensitized resistance ovarian tumor xenografts to cisplatin in vivo. In conclusion, our data supported that HK2 promotes cisplatin resistance in ovarian cancer by enhancing drug-induced, ERK-mediated autophagy. Therefore, targeting HK2 may be a new therapeutic strategy to combat chemoresistance in ovarian cancer.
Keywords: Autophagy; Cisplatin resistance; Hexokinase 2; Ovarian cancer.
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