Andrographolide impedes cancer stemness and enhances radio-sensitivity in oral carcinomas via miR-218 activation

// Po-Yu Yang 1, 2, 4, * , Pei-Ling Hsieh 3, * , Tong Hong Wang 5, 6, 7, * , Cheng-Chia Yu 1, 2, 3, 4, * , Ming-Yi Lu 1, 2, 3, 4 , Yi-Wen Liao 1 , Tzu-Hsin Lee 1, 2 , Chih-Yu Peng 1, 2, 3, 4 1 School of Dentistry, Chung Shan Medical University, Taichung, Taiwan 2 Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan 3 Institute of Oral Sciences, Chung Shan Medical University, Taichung, Taiwan 4 Oral Medicine Center, Chung Shan Medical University, Taichung, Taiwan 5 Tissue Bank, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan 6 Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Tao-Yuan, Taiwan 7 Graduate Institute of Health Industry Technology, Chang Gung University of Science and Technology, Tao-Yuan, Taiwan * These authors contributed equally to this work Correspondence to: Chih-Yu Peng, email: cyp@csmu.edu.tw Keywords: oral squamous cell carcinomas, andrographolide, miR-218, cancer stemness Received: October 31, 2016 Accepted: November 23, 2016 Published: December 01, 2016 ABSTRACT Current evidence suggests that oral cancer stem cells (OCSCs) possess high tumorigenic and metastatic properties as well as chemo- and radioresistance. In this study, we demonstrated that andrographolide, the main bioactive component in the medicinal plant Andrographis, significantly reduced oncogenicity and restored radio-sensitivity of ALDH1 + CD44 + OCSCs. Mechanistic studies showed that andrographolide treatment increased the expression of microRNA-218 (miR-218), leading to the downregulation of Bmi1. We showed that knockdown of miR-218 in ALDH1 − CD44 − non-OCSCs enhanced cancer stemness, while silencing of Bmi1 significantly counteracted it. Furthermore, we found tumor growth was reduced in mice bearing xenograft tumors after andrographolide treatment via activation of miR-218/Bmi1 axis. Together, these data demonstrated that the inhibition of tumor aggressiveness in OCSCs by andrographolide was mediated through the upregulation of miR-218, thereby reducing Bmi1 expression. These findings suggest that andrographolide may be a valuable natural compound for anti-CSCs treatment of OSCC.