Tetramethoxychalcone Inhibits Human Oral Cancer Cell Proliferation and Migration via p 53-mediated Mitochondrial-dependent Apoptosis

Background/Aim: The current study aimed to identify an attractive target against human oral squamous cell carcinoma (OSCC). Materials and Methods: The effect of 3,3’,4’,5’-tetramethoxychalcone (TMC) on OSCC cell proliferation, cell-cycle phase distribution, expression of markers of cell apoptosis, and cell migration were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, western blot, and transwell migration assay, respectively. Results: Experimental results revealed that TMC inhibited the OSCC cell proliferation (fifty percent inhibitory concentrations range=1.0-4.5 μM) by inducing G2/M phase arrest of the cell cycle. TMC caused DNA double-strand breaks, and enhanced expression of caspase-3 and -9, poly (ADP-ribose) polymerase, cytochrome c, calpain-1 and -2, phosphorylation of histone H2AX, phosphorylation of checkpoint kinases 2, p53, BCL2-antagonist/killer and BCL2associated × protein, while reducing the mitochondrial membrane potential, and expression of B-cell lymphoma-2. In addition, TMC reduced the migration potential of OSCC cells by attenuating the C-C chemokine ligand 5/C-C chemokine receptor type 5 axis. Conclusion: These data indicate that TMC may be considered an interesting target for further development of chemotherapeutic agents against oral cancer. Oral squamous cell carcinoma (OSCC) is one of the most common malignant neoplasms in Asian populations (1, 2). It is known that OSCC development is partly facilitated by chronic epithelial irritation and that this tumor occurs more frequently in smokers or individuals who consume excessive amounts of alcohol. Despite advances in diagnostic and therapeutic modalities, the prognosis of OSCC still remains poor, with 5-year survival rates of less than 50%. OSCC exhibits the highest levels of local invasiveness and metastasis to cervical lymph nodes (3). Molecular analyses have shown that the pathogenesis of OSCC is a multi-factorial and multi-step process reflecting the alterations derived from chromosomal instability (4). These events occur via de-regulation of tumorsuppressor genes and the overexpression of numerous oncogenes (5). The outcome of OSCC is mainly dependent on chemotherapeutic drug, radiation, and the feasibility of surgical treatment (5). Non-specific and toxic side-effects in normal cells are commonly observed with the currently available drugs, such as 5-fluorouracil (5-FU), cisplatin and teniposide (6). Currently, there is no effective chemotherapy available for the treatment of unresectable OSCC. Therefore, there is a need to identify potential therapeutic agents that are effective against OSCC and minimize toxicity to surrounding normal cells. In OSCC, the migration of cancer cells into maxillary and mandibular bones is a common clinical problem (3). Clinical evidence showed high levels of tissue or plasma C-C chemokine ligand 5 (CCL5) [also known as regulated upon activation normal T cell expressed and secreted (RANTES)], 1811 *These Authors contributed equally to this work. Correspondence to: Yew-Min Tzeng, Institute of Biochemical Sciences and Technology, Chaoyang University of Technology, Taichung, Taiwan, R.O. C. Tel: +886 423323000 ext. 4471, Fax: +886 423395870, e-mail: ymtzeng@cyut.edu.tw and Chih-Ho Lai, Department of Microbiology, Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan, R.O. C. Tel: +886 422052121 ext. 7729, Fax: +886 42333641, e-mail: chl@mail.cmu. edu.tw