UVB에 의해 손상된 각질세포에 대한 epigallocatechin-3-gallate의 세포 보호 효과

Abstract

Ultraviolet B (UVB) irradiation is an important inducer of several biological changes in skin, including sunburn, premature skin aging, and skin cancer, which are mainly mediated by direct DNA damage or production of reactive oxygen species (ROS). The increased generation of ROS by oxidative stress can cause the disruption of natural defense mechanisms. Green tea is a rich source of polyphenols, and epigallocatechin-3-gallate (EGCG) is a major constituent of green tea polyphenols. Benefical effects of green tea on anticancer and antioxidant properties have been mediated by EGCG. In this study, effects of EGCG on cell proliferation and UVB-induced apoptosis of human keratinocytes (HaCaT) were determined with UVB-induced keratinocytes. We demonstrated that EGCG can stimulate the proliferation of the UVB-induced HaCaT cells with dose-dependent manner. EGCG increased the phosphorylation of ERK and Akt proteins. Futhermore, EGCG increased Bcl-2 protein expression but decreased Bax protein expression after UVB irradiation. EGCG increased translocation of Nrf-2 from cytosol into nuclear. UVB-induced apoptosis is suppressed via decrease of cleaved-caspase-3 followed by reduced cleaved-PARP by EGCG treatmant. Moreover, EGCG decreased phosphorylation of JNK and p38 proteins. In conclusion, high antioxidant activity EGCG promotes the survival of HaCaT cells through the activation of protective cell signaling mechanisms and inhibits UVB-induced apoptosis via suppresion of cell death signaling mechanisms.