Human epididymis protein 4 promotes P‑glycoprotein‑mediated chemoresistance in ovarian cancer cells through interactions with Annexin II.

The aim of the present study was to investigate the effects of human epididymis protein 4 (HE4) on drug resistance and its underlying mechanisms. The associations among proteins were detected by immunoprecipitation and immunofluorescence assays. Then, stably transfected cell lines CAOV3‑HE4‑L and CAOV3‑A2‑L expressing HE4 short hairpin (sh)RNAs and ANXA2 shRNAs, respectively, were constructed. MTT assay, immunocytochemistry, western blotting, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and flow cytometry were employed to examine drug sensitivity, as well as the expression and activity of P‑glycoprotein (P‑gp). HE4 and P‑gp in epithelial ovarian cancer tissues were assessed via immunohistochemistry. MicroRNAs that targeted the P‑gp gene, ABCB1, were predicted using bioinformatics methods, and their expression was evaluated by RT‑qPCR. The common signaling pathways shared by HE4, ANXA2 and P‑gp were selected by Gene Set Enrichment Analysis (GSEA). The interaction of HE4, ANXA2 and P‑gp were confirmed. P‑gp expression was positively associated with HE4 and ANXA2 expression, respectively. Moreover, it was observed that there was no significant rescue of P‑gp expression in CAOV3‑A2‑L cells following the administration of active HE4 protein. In addition, the expression of HE4 and P‑gp in ovarian cancer tissues of drug‑resistant patients were higher compared with that of the drug‑sensitive group (P<0.05). Furthermore, the results revealed that hsa‑miR‑129‑5p was significantly increased accompanied by decreased HE4 or ANXA2 expression and P‑gp expression in CAOV3‑HE4‑L and CAOV3‑A2‑L cells. GSEA analyses disclosed that HE4, ANXA2 and P‑gp genes were commonly enriched in the signaling pathway involved in regulating the actin cytoskeleton. These results indicated that HE4 promotes P‑gp‑mediated drug resistance in ovarian cancer cells through the interactions with ANXA2, and the underlying mechanism may be associated with decreased expression of hsa‑miR‑129‑5p and dysregulation of the actin cytoskeleton signaling pathway.