HaCaT 각질형성세포에서 자외선 B에 대한 세포자멸사 및 자가포식현상 유도

Abstract

Background: UVB irradiation induces apoptosis or/and autophagy through several molecular pathways in keratinocytes. However, the precise molecular mechanism of UVB-induced autophagy is largely unknown in keratinocytes. Objective: The purpose of this study was to investigate the molecular mechanisms of UVB-induced apoptosis and autophagy in HaCaT cell lines. Methods: Cells were irradiated by UVB (Westinghouse FS-40 sunlamps) with various doses (0, 30, 60, 120, 240 mJ/cm2). The expression levels of caspase-3, Bax, Bcl2, Bcl-XL and LC3 were confirmed by Western blot analysis in UVB-irradiated HaCaT cell lines. Apoptotic cells were analyzed by PI staining, and autophagy cells were analyzed by immunofluorescent staining. Results: The expression of Bcl-XL decreased from UVB 60 mJ/cm2 and Bcl2 decreased from UVB 240 mJ/cm2. The expression of caspase-3 was increased from UVB 120 mJ/cm2 . These data showed that UVB-induced apoptosis is mediated by up-regulation of caspase-3 and down-regulation of Bcl2 and Bcl-XL. Furthermore, the expression of LC3 increased from UVB 120 mJ/cm2. In addition, autophagy formation was observed in few fractions of apoptotic HaCaT cells in immunofluorescent staining; most apoptotic cells did not show autophagy formation. Moreover, autophagy formation inhibitor treatment induced a slight increment of apoptotic cell population under UVB irradiation. Conclusion: UVB irradiation induces not only apoptotic cell death but also autophagy formations; these events may create a defense mechanism for the prevention of apoptosis in UVB-treated HaCaT cells.