Premature senescence and the protein expressions of P53 and P16 in HaCaT cells after UVB exposure

Objective: To explore the effects of ultraviolet B (UVB) on the premature senescence of human immortalized keratinocytes HaCaT cells and the possible underlying molecular mechanism. Methods: HaCaT cells were exposed with UVB of different doses (20, 50, 80 and 100 mJ/cm²). At 72 h after exposure, cellular morphology was observed by Giemsa staining, cell proliferation was detected by clone formation assay, and the proportion of premature senescence cells was detected by β-galactosidase staining. The number change of lysosomes was detected by Lyso-Tracker Red fluorescence probe at 24, 48 and 72 h after exposure. Cell migration was measured by scratch test at 24 h and 48 h after exposure. The protein expressions of p53 and p16 related to premature senescence were detected by Western blot assay at 72 h after exposure. Results: After UVB exposure, HaCaT cells showed a premature senescence phenotype. At 72 h after exposure, the cell volume increased (F = 115.18, P < 0.05), the cell proliferation ability decreased (F = 410.32, P < 0.05), the activity of β-galactosidase increased (F = 16.31, P < 0.05), and the expressions of P53 and P16 increased. In addition, the number of lysosomes increased at 24, 48, and 72 h after exposure (F = 17.65, 38.36, 13.66, P < 0.05), and cell migration capacity was inhibited at 24 and 48 h after exposure (F = 8.21, 11.48, P < 0.05). Conclusions: UVB exposure can induce premature senescence of HaCaT cells by increasing the expression of p53 and p16 proteins. (authors)