Induction of Mitotic Delay in Pharyngeal and Nasopharyngeal Carcinoma Cells Using an Aqueous Extract of Ajuga bracteosa

Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia, for which radiotherapy and/or chemotherapy are the primary treatment methods. Many herbs are known to have potential uses in chemotherapy; however, the mechanisms underlying the observed antitumor activity of Ajuga bracteosa (AB) against NPC remain unclear. We explored the antitumor effects of AB, which was shown specifically to induce mitotic delay in pharyngeal (Detroit 562) and nasopharyngeal (Hone-1) cancer cells. Proliferation of cancer cells after exposure to aqueous extract of A. bracteosa (AEAB) was assessed using the MTT assay. DNA content and cell cycle arrest induction were analyzed using flow cytometry. The expression of checkpoint kinase 2 (CHK2), cell division control protein 2 (CDC2), and cyclin B1 was investigated using qRT-PCR and Western blot analysis. Results indicated the inhibition of cancer cell growth following exposure to AEAB. In addition, AEAB induced the accumulation of G(2)/M-phase cells in cancer cell through the disassociation of CDC2/cyclin B1 complex. Our findings suggested that, in addition to the known effects of AEAB in NPC prevention, it may have antitumor activities against NPC cells. In conclusion, AEAB inhibits the growth of and induces mitotic delay in cancer cells, supporting its use as an anticancer agent.