Objective : To characterize the antitumorigenic potential of Apamin, one of the major components of bee venom, its effects on cell proliferation and the mitogen-activated protein kinase (MAPK) signal transduction pathway were characterized using the human melanoma cell line SK-MEL-2.
Methods & Results : Cell counting analysis for cell death demonstrated that consistent with a previous results, SK-MEL-2 cells treated with 0.5-2.0㎍/ml of Apamin showed no recognizable cytotoxic effect whereas detectable induction of cell death was identified at concentrations over 5.0㎍/ml. [3H]thymidine incorporation assay for cell proliferation demonstrated that DNA replication of SK-MEL-2 cells is inhibited by Apamin in a dose- and time-dependent manner. To explore whether Apamin-induced growth suppression is associated with the MAPK signaling pathway, phosphorylation of Erk, a function mediator of MAPK growth-stimulating signal, was examined Western blot assay using a phospho-specific Erkl/2 antibody. A significant increase of Erkl/2 phosphorylation level was observed in Apamin-treated cells compared with untreated control cells. Qantitative RT-PCR analysis revealed that Apamin inhibit expression of MAPK downstream genes such as c-Jun, c-Fos, and cyclin Dl but not expression of MAPK pathway component genes including Ha-Ras, c-Raf-1, MEKI, and Erk.
Conclusion : It is strongly suggested that the antitumorigenic activity of Apamin might result in part from its inhibitory effect on the MAPK signaling pathway in human melanoma cells SK-MEL-2.
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