Expression of Apoptosis Related Genes from HaCaT Cell after UVB Irradiation

Kang, Min Chul; Lee, Kyu Suk

Abstract

BACKGROUND: Ultraviolet B (UVB) radiation is a major harmful environmental factor causing cutaneous changes such as sunburn, skin aging and skin cancer. Excessive UVB irradiation induces apoptosis of keratinocytes through several molecular pathways. However, the precise molecular mechanisms have been underinvestigated.
OBJECTIVE
The purpose of this study was to investigate expression levels of apoptosis-related genes in UVB- irradiated HaCaT ketratinocyte cell lines.
METHODS
Cells were irradiated by UVB at various doses (0, 100, 200 and 400 mJ/cm2). Expression levels of caspases, Bax, Bcl2, and Bcl-XL were confirmed by RT-PCR analysis and western blotting.
RESULTS
Expression of cytochrome C was increased followed by activation of caspase-3, 8 and 9 in UVB-irradiated HaCaT cells. Furthermore, the expression of Bcl-XL was decreased from UVB 200 mJ/cm2 and Bcl2 was decreased weakly from UVB 400 mJ/cm2, implying that the expression of Bcl-XL is more sensitive to UVB. Interestingly, the down-regulation of Bcl-XL may be mediated by proteasome dependent pathways.
CONCLUSION
Excessive UVB-irradiated HaCaT cells undergo apoptotic cell death following activation of caspases; degradation of Bcl-XL is particularly sensitive to UVB.