Promotive role of recombinant HE4 protein in proliferation and carboplatin resistance in ovarian cancer cells

Available evidence on the proliferation-promoting effect of HE4 remains controversial, and few studies have been carried out on the molecular mechanism of chemoresistance mediated by HE4. The aim of the present study was to investigate the influence of exogenous recombinant HE4 protein on proliferation and resistance to carboplatin in ovarian cancer cells. The human ovarian cancer cell line (SKOV-3) was exposed to recombinant HE4 protein (0-1 g/ml) for different durations based on the schemes. Cell viability was evaluated by Cell Counting Kit-8 and colony formation assays. Cell cycle distribution and apoptosis were analyzed by flow cytometry. Markers of apoptosis (Bax and Bcl-2) were assessed by western blotting. Furthermore, Affymetrix microarray analysis was performed to investigate transcriptome profiling. The differential expression of four genes was verified by quantitative real-time PCR. The HE4 protein enhanced cell viability, promoted accumulation of cells in the G2/M phase and attenuated carboplatin-induced apoptosis. HE4 markedly decreased the Bax/Bcl-2 ratio. Candidate genes (387) (236 upregulated and 151 downregulated) were obtained by microarray analysis. Among those upregulated, several Gene Ontology (GO) terms related to cell cycle regulation and proliferation were significantly overrepresented and those within the downregulated dataset included genes involved in several aspects of the DNA damage response such as positive regulation of apoptosis. No information concerning the EGFR-MAPK pathways in a recent report on HE4 was acquired. The mRNA expression of the candidate genes determined by quantitative real-time PCR was significantly correlated with the microarray data. The present study indicates that the HE4 protein plays a promotive role in the proliferation and resistance to carboplatin in ovarian cancer cells, implicating the value of HE4 to predict tumor growth potential and resistance to platinum-based chemotherapy in epithelial ovarian cancer (EOC).