Regulatory mechanism of UVB-induced autophagy and apoptosis in A375 cells / 中国职业医学

ABSTRACT

OBJECTIVE: To investigate the effect of ultraviolet B( UVB) on autophagy and apoptosis in human epidermal melanoma A375 cells. METHODS: i) A375 cells at logarithmic growth phase were exposed to UVB at doses of 10. 0 and15. 0 m J/cm~2. Then cells were collected at time point of 3,6,9 and 12 hours after irradiation. The effect of UVB on cell autophagy was observed by monodansylcadaverine staining and the effect of UVB on cell apoptosis was observed by acridine orange/ethidium bromide staining. ii) A375 cells of 10. 0 m J/cm~2 group and 15. 0 m J/cm~2 group were exposed to corresponding dose of UVB irradiation. Then cells were collected at time point of 18,24,36 and 48 hours after irradiation,and cell survival rate was examined using CCK-8 assay. iii) A375 cells were irradiated with UVB at doses of 10. 0 and15. 0 m J/cm~2 and then cells were collected at time point of 3,6,9 and 12 hours after irradiation. After that,A375 cells were irradiated at doses of 2. 5,5. 0,7. 5,10. 0 and 15. 0 m J/cm~2 of UVB,then cells were collected at time point of 9 hours after irradiation. The expressions of B-lymphoblastoma-2( Bcl-2),Bcl-2 related X protein( Bax),Bcl-2 interacting protein( Beclin-1) and microtubule-associated protein 1 light chain 3( LC3) Ⅱ were detected by Western blotting. A375 cells with no UVB irradiation were set as the control( pseudo-irradiation) in each experiment. RESULTS: i) Both autophagy and apoptosis of A375 cells induced by UVB irradiation at doses of 10. 0 and 15. 0 m J/cm~2 increased with time after irradiation. The effect on autophagy decreased at 12 hours time point with 15. 0 m J/cm~2 UVB irradiation. ii) The cell viability increased with time after irradiation in the 10. 0 and 15. 0 m J/cm~2 groups( P < 0. 05). From 18-48 hours after irradiation,the cell viability of the 10. 0 and 15. 0 m J/cm~2 groups was lower than that of the control group( P < 0. 05).From 24-48 hours after irradiation,the cell viability of the 15. 0 m J/cm~2 group was lower than that of the 10. 0 m J/cm~2 group( P < 0. 05). iii) The relative expression of Beclin-1 and LC3 Ⅱ protein at the 10. 0 m J/cm~2 group increased with time after 0-12 hours irradiation( P < 0. 05). The above changes of the 15. 0 m J/cm~2 group were observed within 0 to 9 hours,and the above two autophagy-related proteins were significantly decreased at the 12 hours time point( P < 0. 05).The relative expression of Bcl-2 protein at the 10. 0 and 15. 0 m J/cm~2 groups decreased with increasing time from 3 to 12 hours after irradiation( P < 0. 05). The relative expression of Bax protein increased with time from 0 to 12 hours after irradiation( P < 0. 05). The relative expression of Beclin-1 and LC3 protein in cells at 0. 0-10. 0 m J/cm~2,and the relative expression of Bax protein in cells at 0. 0-15. 0 m J/cm~2 increased with increase of irradiation dose( P < 0. 05). The relative expression of Bcl-2 protein decreased with increase of irradiation dose at 5. 0-15. 0 m J/cm~2( P < 0. 05). CONCLUSION: Autophagy and apoptosis of A375 cells can be induced by UVB irradiation at doses of 10. 0 and 15. 0 m J/cm~2. Autophagy induced by UVB irradiation at 10. 0 m J/cm~2 partially resisted the induction of apoptosis by UVB and enhanced cell viability. 15. 0 m J/cm~2 UVB-induced autophagy was insufficient to exert the above-mentioned effects,and the induction of apoptosis was the dominant effect.