Anticancer Effects of Astaxanthin and alpha-tocopherol in Esophageal Cancer Cell Lines

ABSTRACT

BACKGROUND/AIMS: Astaxanthin (AX) has been attributed with potential for protecting the organism against different types of cancer due to its anti-oxidant activity. Also several in vivo and in vitro studies suggest certain naturally occurring vitamin E (i.e. alpha-tocopherol) as promising anticancer agents. We assessed the effect of AX and alpha-tocopherol (AT) respectively and their combination on human esophageal cancer cell lines to investigate the mechanism of anticancer effect and their therapeutic potential. MATERIALS AND METHODS: Two human esophageal cancer cell lines (TE-1, TE-4) were exposed to AX (6 to 10 microg/mL) and AT (20 to 100 microM) for 24 hours. Quantification of proliferation was performed by MTT assay. Cell cycle machinery proteins such as p-AKT, p-p38, cyclin D1, p27 and caspase-3 were investigated by Western blot. RESULTS: Significant inhibition of cell proliferation of AX and AT was observed in TE-4 cell line by a dose-dependent manner. Furthermore, AX and AT as single agents increased the protein expression of p27 and cleaved caspase-3 in TE-4 cell line. The combination of the two agents decreased the expression of cyclin D1, however they did not demonstrate pro-apoptotic effect. CONCLUSIONS: AX and AT as single agents are effective at inhibition of cell proliferation and induce apoptosis by the modulation of cell cycle machinery proteins in esophageal cancer cell lines. However, our data could not suggest that their combination has any cooperative apoptotic effect.