Melatonin inhibits AP-2β/hTERT, NF-κB/COX-2 and Akt/ERK and activates caspase/Cyto C signaling to enhance the antitumor activity of berberine in lung cancer cells

// Jian-Jun Lu 1, * , Lingyi Fu 2, 3, * , Zhipeng Tang 4, * , Changlin Zhang 2 , Lijun Qin 5 , Jingshu Wang 2 , Zhenlong Yu 4 , Dingbo Shi 2 , Xiangsheng Xiao 2 , Fangyun Xie 2 , Wenlin Huang 2, 6 , Wuguo Deng 2, 6 1 Department of Thoracic Surgery, The First Affiliated Hospital, Yat-sen University, Guangzhou, China 2 Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China 3 Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China 4 Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China 5 Department of Pediatrics, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China 6 State Key Laboratory of Targeted Drug for Tumors of Guangdong Province, Guangzhou Double Bioproduct Inc., Guangzhou, China * These authors have contributed equally to this article Correspondence to: Jian-Jun Lu, e-mail: ljj508@21cn.com Wuguo Deng, e-mail: dengwg@sysucc.org.cn Keywords: melantonin, berberine, lung cancer, hTERT, COX-2 Received: August 04, 2015      Accepted: November 16, 2015      Published: November 27, 2015 ABSTRACT Melatonin, a molecule produced throughout the animal and plant kingdoms, and berberine, a plant derived agent, both exhibit antitumor and multiple biological and pharmacological effects, but they have never been combined altogether for the inhibition of human lung cancers. In this study, we investigated the role and underlying mechanisms of melatonin in the regulation of antitumor activity of berberine in lung cancer cells. Treatment with melatonin effectively increased the berberine-mediated inhibitions of cell proliferation, colony formation and cell migration, thereby enhancing the sensitivities of lung cancer cells to berberine. Melatonin also markedly increased apoptosis induced by berberine. Further mechanism study showed that melatonin promoted the cleavage of caspse-9 and PARP, enhanced the inhibition of Bcl2, and triggered the releasing of cytochrome C (Cyto C), thereby increasing the berberine-induced apoptosis. Melatonin also enhanced the berberine-mediated inhibition of telomerase reverses transcriptase (hTERT) by down-regulating the expression of AP-2β and its binding on hTERT promoter. Moreover, melatonin enhanced the berberine-mediated inhibition of cyclooxygenase 2 (COX-2) by inhibiting the nuclear translocation of NF-κB and its binding on COX-2 promoter. Melatonin also increased the berberine-mediated inhibition of the phosphorylated Akt and ERK. Collectively, our results demonstrated that melatonin enhanced the antitumor activity of berberine by activating caspase/Cyto C and inhibiting AP-2β/hTERT, NF-κB/COX-2 and Akt/ERK signaling pathways. Our findings provide new insights in exploring the potential therapeutic strategies and novel targets for lung cancer treatment.