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.
ABSTRACT
Objective To study the effect of PM2.5 combined with UVB treatment on human keratinocytes HaCaT. Methods The PM2.5 in the air was collected in Guangzhou and the metal ingredients were analyzed. The cells were divided into four groups:negative control group(NC group),simple PM2.5 treatment group with the concentration of IC50(PM2.5 group),simple UVB irradiation group with the dose of 30 mJ/cm2(UVB group)and PM2.5 combined with UVB treatment group(combined treatment group). The effects of different treatments on cell viability were measured by MTT assay and those of different treatments on apoptosis were detected by flow cytometry. The expressions of PARP and LC3 protein were detected by Western blot. Results The metal components in PM2.5 samples included Ca ,Zn ,Ba ,Al ,Cu ,Pb ,etc. After the treatment of PM2.5 on HaCaT cells ,we concluded that the IC50 was about 300 μg/mL. The inhibitory effect on cell viability after 24 h in different groups showed significant difference (P < 0.001) and the viability of the combined treatment group was the lowest (P < 0.001). Flow cytometry analysis showed that compared with that of NC group,the apoptosis rate of PM2.5 group(P < 0.01),UVB group(P < 0.01)and the combined treatment group(P < 0.01)increased,but the apoptosis rate in the combined treatment group was higher than that of PM2.5 group(P < 0.05),but lower than that in UVB group(P < 0.01). Western blot showed that the level of LC3-Ⅱ and PARP in another three groups was higher than that of NC group;PARP in the combined treatment group was lower than that in UVB group and LC3-Ⅱ increased compared with that in PM2.5 and UVB group. Conclusion PM2.5 can increase the harm of UVB on HaCaT cells and the main mechanism may be through increasing autophagy rather than apop-tosis.
ABSTRACT
Objective To investigate the autophagy effect and the crosstalk with apoptosis by UV in A375 cells.Methods GFP-RFP-LC3 lentivirus were used to evaluate the effect of autophagy after being irradiated with UV of different doses (0、10、30、50 mJ/cm2).After being treated with 30 mJ/cm2 irradiation,the apoptosis rate of A375 with or without autophagy inducer was evaluated by annexin V-FITC/PI with flow cytometry.Western blot was used to distinguish the biomarker of autophagy (BECN,LC3) and apoptosis (Caspase 3,9).Results After being irradiated with 10 mJ/cm2 or 30 rnJ/cm2 UV,the autophagosome was observed at 6 h and rich at 9 h.However,the dots of autophagy had been abundant continually from 3 h with 50 mJ/cm2.The ability of inducing autophagy of UVB is stronger than UVA.UVA and UVB showed synergistic effect in autophagy with the dose of 30 mJ/cm2.The Caspase 3 and Caspase 9 proteins were downregulated after 30 mJ/cm2 UV irradiation with autophagy biomarkers increasing,whereas the apoptosis biomarkers were enriched with the inhibition of autophagy.Conclusions UV can induce autophagy with more significant effect of UVB.Autophagy paly protective role by delaying apoptosis after 30 mJ/cm2 UV irradiation in A375.