Chloroform extract of Citrus unshiu Markovich peel induces apoptosis and inhibits stemness in HeLa human cervical cancer cells

Cervical cancer is the second most common cancer among women worldwide. However, chemotherapies for this cancer often cause many side effects and chemoresistance. Citrus unshiu Markovich peel (CECU) has been used as a traditional medicine for the treatment of various diseases in East Asia. Recently, the anticancer activities and mechanisms of action of CECU extract have been reported in a number of different cancer cell types, but no study has evaluated the therapeutic effect of this natural product on cervical cancer cells. In the current study, the anticancer activity and the underlying molecular mechanism of the chloroform extract of CECU was investigated on HeLa human cervical cancer cells. The results showed that CECU effectively inhibited the proliferation and migration of HeLa cells. Treatment of cells with CECU led to cell cycle arrest at the G2/M phase and activation of extrinsic and intrinsic apoptotic pathways. Furthermore, the proliferation inhibitory effect of CECU was due to the inactivation of AKT and ERK signaling, upregulation of p53 and p21, and downregulation of cyclin B1 and cyclin D1, but not reactive oxygen species (ROS) generation. Furthermore, CECU inhibited the stem-like features of HeLa cells by downregulating key cancer stemness biomarkers. Therefore, CECU may be an effective complementary and alternative medicine for the prevention and treatment of cervical cancer.