Inhibition of growth and induction of differentiation of metastatic melanoma cells in vitro by genistein: chemosensitivity is regulated by cellular p53.

S Rauth,A Green,J Kichina

doi:10.1038/bjc.1997.268

Abstract

We have investigated the effect of the soybean isoflavone genistein on the growth and differentiation of human melanoma cells. Four human melanoma cell lines, either completely lacking or containing different levels of wild-type p53, were treated with genistein in vitro in culture. It has been found that genistein significantly inhibited cell growth and that the chemosensitivity might depend on cellular p53 content. Specifically, the data suggest that high levels of wild-type p53 expression make cells resistant to genistein's growth-inhibitory action. Further support for this observation came from the stable transfection studies in which p53 transfectants expressing high levels of wild-type p53 became resistant to genistein. With respect to cell differentiation, our study showed that genistein increased melanin content and tyrosinase activity and caused the cells to form dendrite-like structures. Cells lacking p53 responded more than cells with p53 to dendrite-like structure formation. We also observed that genistein-induced differentiation involved an increase in tyrosinase mRNA level; the mechanisms by which genistein increases tyrosinase transcripts remain to be elucidated. Genistein treatment of the melanoma cell lines resulted in cell cycle arrest at G2/M check point and no significant apoptosis was observed.

Highlights

We examined the effect of genistein on the growth and differentiation of melanoma that arises from normal melanocytes commonly located in skin
Cells either lacking or containing low p53 protein levels were more sensitive to genistein-induced growth arrest than cells with high p53. Further support for these observations came from gene transfer studies, in which stable transfectants expressing high levels of wild-type p53 became resistant to genistein's growth-inhibitory action
The data presented in this report demonstrate that genistein can arrest growth and enhance differentiation of metastatic melanoma cells; more importantly, the chemosensitivity of these cells may be regulated by cellular p53

Summary

Methods

The human melanoma cell lines, UISO-MEL-6, UISO-MEL-4, UISO MEL-7 and UISO-MEL-8, established and characterized in our laboratory (Rauth et al, 1994a, b), have been used in the present study. All cells were maintained in MEM-H [minimum essential medium with Hanks' balanced salt solution (Gibco, Grand Island, NY, USA)] containing fetal calf serum (2%), L-glutamine (1%), non-essential amino acids and penicillin-streptomycin (0.2%). The human wild-type p53 expression plasmid, pC53-SN3, and the expression vector without p53 cDNA, pCMVNeo, originally constructed by Bert Vogelstein (Baker et al, 1990), were obtained from Professor Kiranur Subramanian. Genistein was obtained from Sigma Chemical Co

Results

Discussion

Conclusion