Canthaxanthin and tumor growth in mice

Abstract

Canthaxanthin (CX), a non-provitamin A carotenoid, has been shown to exert a variety of effects on cells of the immune system and to have tumor-specific cytopathic effects in vivo and in vitro. In the present study, CX was shown to inhibit the in vitro growth of three murine tumor cell lines, JB/MS melanoma, B16F10 melanoma, and PYB6 fibrosarcoma. This effect was dose-dependent up to a concentration of CX of 10⁻⁴M. In contrast, the growth of NIH-3T3 fibroblasts was enhanced following a 96 hr incubation with 10⁻⁴M CX. A dietary supplement of 1% CX retarded tumor growth in LP-BM5 retrovirus-infected female C57BL/6 mice after tumor challenge, but had no effect on tumor growth in normal, uninfected animals. Although, NK activity and T and B subpopulations were not modified by dietary CX after tumor challenge, irrespective of whether mice had been virus-infected, there was a slight enhancement of mitogen-stimulated IFN-τ production by virus-infected murine spleen cells when compared with non-infected cells. We suggest that CX has potential as a modifier of cancer cell growth, especially in situation where impairment of the immune system has occurred as a result of viral infection.