Comparison of the Expression Levels of Anti-proliferative Genes between HaCaT Keratinocytes and Squamous Cancer Cell Lines after UVB Irradiation

Kim, Chang Wook; Cho, Jae We; Lee, Kyu Suk

Abstract

BACKGROUND: Impairment of the DNA repair system after UVB irradiation is the key factor in transformation of normal keratinocytes to squamous cancer cells (SCC). Among anti-proliferative genes (APRO), BTG1, BTG2, and TOB genes are involved in the repairing of DNA damage and, BTG3 and TOB 2 are involved in differentiation and cell cycle arrest in human cells, respectively. However, the expressions of APRO genes in SCC and human keratinocytes after UVB irradiation are largely unknown.
OBJECTIVE
The purpose of this study was to investigate the expression levels of APRO genes in UVB-irradiated HaCaT keratinocyte lines and SCC cell lines.
METHODS
Cells were irradiated with UVB at various doses (0, 100, 200, 300 mJ/cm2), then total RNA was extracted from the cells. The expression of genes were confirmed by RT-PCR analysis using specific primers. The results were obtained from two independent experiments.
RESULTS
The expression of BTG1, BTG2, and TOB2, but not BTG3 and TOB, were markedly increased in UVB-irradiated HaCaT cells, compared to UVB-irradiated SCC. To confirm the expression levels of BTG1, BTG2, and TOB2 genes correlated with extent of DNA damage or susceptibility to cell death by UVB, we carried out staining of surviving UVB-irradiated HaCaT and SCC cell lines. Interestingly, it was found that the number of surviving HaCaT colonies was higher than SCC cell lines.
CONCLUSION
The number of surviving colonies, as well as the expression of BTG1, BTG2, and TOB2 after UVB irradiation were higher in HaCaT cells than the SCC cell lines, suggesting that the gene expression of BTG1, BTG2, and TOB2 in HaCaT cells might be involved in reducing the death of UVB-irradiated cells by repairing DNA damage.