Leptomycin B enhances CDDP-sensitivity via nuclear accumulation of p53 protein in HPV-positive cells

Cervical cancer, which commonly contains a wild-type p53 gene, is highly correlated with human papilloma virus (HPV) infection. Because the oncoprotein E6, derived from HPV, inhibits the function of p53 protein, the inhibition of apoptosis via the p53 pathway by HPV may be related to cisplatin (CDDP)-sensitivity in cervical cancer. We conducted the present study to determine whether and how HPV is related to CDDP-sensitivity in HPV-positive cervical cancer cells. We used cervical carcinoma cell lines HeLa with integrated HPV 18 and SiHa with integrated HPV 16. An HPV-negative cell line, Yumoto, with wild-type p53 gene was used as a control. Leptomycin B (LMB) enhanced sensitivity to CDDP and CDDP-induced apoptosis in HeLa and SiHa cells, but not in Yumoto cells. After exposure to LMB or CDDP alone, we observed weak p53 staining in HeLa, SiHa and Yumoto cells. Nuclear p53 staining was significantly increased by combined treatment with CDDP and LMB in HeLa and SiHa cells, but not in Yumoto cells. The expression of p53 and Bax protein increased with exposure to CDDP and was enhanced by LMB in HeLa and SiHa cells. The present study demonstrated that LMB enhanced CDDP-sensitivity via nuclear accumulation of p53 protein in HPV-positive cells.