Polyphenols from green tea inhibit the growth of melanoma cells through inhibition of class I histone deacetylases and induction of DNA damage
Ram Prasad1 and Santosh K. Katiyar1,2,3,4,5
1 Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL, USA
2 Environmental Health Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
3 Nutrition Obesity Research Center, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA
4 Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL, USA
5 Birmingham Veterans Affairs Medical Center, Birmingham, AL, USA
Correspondence:
Santosh K. Katiyar, email:
Keywords: Cell viability, melanoma cells, green tea polyphenols, histone deacetylase, DNA damage
Received: October 01, 2014 Accepted: February 13, 2015 Published: February 14, 2015
Abstract
Melanoma is the leading cause of skin cancer-related deaths. We have examined the effect of green tea polyphenols (GTPs), a natural mixture of epicatechin monomers, on melanoma cancer cell growth and the molecular mechanism underlying these effects using different human melanoma cell lines as an in vitro model. Treatment of melanoma cell lines (A375, Hs294t, SK-Mel28 and SK-Mel119) with GTPs significantly inhibited the cell viability as well as colony formation ability of melanoma cells in a dose-dependent manner. These effects of GTPs were associated with a significant inhibition of histone deacetylase (HDAC) activity, reduction in the levels of class I HDAC proteins, enhancement of histone acetyltransferase (HAT) activity and induction of DNA damage, as detected by Comet assay, in melanoma cells. GTPs-induced decrease in the levels of class I HDAC proteins is mediated through proteasomal degradation. Valproic acid, an inhibitor of HDACs, exhibited a similar pattern of reduced viability and induction of death of melanoma cells. Treatment of A375 and Hs294t cells with GTPs resulted in a decrease in the levels of cyclins and cyclin dependent kinases of G1 phase of cell cycle whereas upregulated the levels of tumor suppressor proteins (Cip1/WAF1/p21, p16 and p53).
