Oxymatrine inhibits the proliferation of CaSki cells via downregulating HPV16E7 expression

Treatment of recurrent and metastatic cervical cancer remains a challenge, especially in developing countries, which lack efficient screening programs. HPV16E7 has been reported to play an important role in the development of cervical cancer. In recent years, oxymatrine, which was traditionally used as anti-malarial agent, has been shown to inhibit tumor growth with low toxicity to normal cells. In the present study, we investigated the mechanisms underlying the antitumor effect of oxymatrine in cervical cancer. The CCK-8 assay was used to compare the proliferation of untreated and oxymatrine-treated cervical cancer CaSki cells. Flow cytometry was applied to observe the effect of oxymatrine on apoptosis- and the cell cycle distribution of CaSki cells. We used qRT-PCR and western blot analysis to determine the mRNA level and protein level of HPV16E7. The HPV16E7 siRNA inhibition was also performed to confirm the effect of downregulating HPV16E7 on the proliferation in CaSki cells. Our results revealed that oxymatrine-treated cells showed time-dependent and dose-dependent inhibition of proliferation and a significant increase in apoptosis. Oxymatrine arrested CaSki cells in G0/G1 phase and S phase while decreased the cells in G2/M phase. The expression of HPV16E7 was significantly downregulated in oxymatrine-treated cells compared with control cells. Knock-down of HPV16E7 effectively inhibited the proliferation of CaSki cells. In conclusion, our data suggest that oxymatrine inhibits cervical cancer growth via downregulation of HPV16E7. Oxymatrine can be considered to be a potential preventive and therapeutic target for cervical cancer.