| Continuous exposure to UV radiation cause progressive damage to skin,primarily due to excess production of reactive oxygen species(ROS).Metformin(N,Ndimethylbiguanide,MET)is a biguanide drug.Currently,metformin is the most common drug used to treat type 2 diabetes.Several studies have reported its therapeutic potential in novel applications such as anticancer,antiaging,and regenerative effects in skin wound healing in young and old mice.However,no studies have reported the antiaging effect and mechanism of metformin on human foreskin fibroblasts under UVAinduced injury.Purpose:In this experiment,human foreskin fibroblasts and guinea pigs were used for in vitro and in vivo experiments to investigate the protective effect and mechanism of metformin on UVA-induced skin photoaging,and evaluate its potential as a skin antioxidant.Methods:1.Primary human foreskin fibroblasts were identified by immunohistochemistry.2.Cell senescence: β-galactosidase staining,and the expressions of the senescence-related genes p53,p21 and p16 detected by q PCR.3.The expression of cell cycle-related proteins CDK2 and cyclin E,and p53,p21,and p16 were detected by q PCR,and the cell apoptosis was detected by flow cytometry.4.Mito tracker was used to detect the level of mitochondrial ROS in HFFs.Western Blot was used to detect the expression of oxidative stress-related signaling pathway P62-Keap1-Nrf2 protein..The expression and distribution of P62 protein were detected by immunofluorescence.The m RNA expression of PGC-1α and Sirt1 was detected by q PCR.5.Guinea pig skin photoaging model was used to observe the general condition of the back skin of guinea pigs.HE staining was used for histopathological examination.ELISA was adopted to detect the expression of oxidation related factor SOD,GSH and MDA in the skin of guinea pigs.Results:1.UVA irradiation can induce the senescence of human foreskin fibroblasts.The results showed that the number of β-galactosidase staining HFFs cells in the UVA irradiation group was more than that in the control group,and the levels of p53,p21,and p16 m RNA were up-regulated in the UVA irradiation group.2.Metformin can improve the aging of HFFs induced by UVA irradiation.The results showed that the m RNA levels of CDK2 and cyclin E in HFFs cells in UVA irradiation group were down-regulated,and the levels of p53,p21 and p16 m RNA were up-regulated,and the apoptosis rate had no significant change,decreased,and the apoptosis rate increased.3.Metformin can alleviate the oxidative stress of HFFs induced by UVA irradiation and restore mitochondrial function.Mito tracker detected the mitochondrial ROS level of HFFs and found that UVA irradiation increased the mitochondrial ROS level of HFFs,and the mitochondrial ROS level of HFFs decreased after metformin treatment.UVA irradiation induced activation of oxidative stress-related pathway P62-Keap1-Nrf2 signaling pathway,and the expression of P62-Keap1-Nrf2 signaling pathway-related proteins decreased after metformin treatment.The levels of PGC-1αand Sirt1 m RNA in UVA group decreased,and the levels of PGC-1α and Sirt1 increased after metformin treatment.4.Metformin can ameliorate skin photoaging induced by UVA irradiation in guinea pigs.HE staining showed that metformin treatment improved skin aging.The expression level of oxidation related factors decreased.Conclusion:1.Metformin can effectively alleviate the senescence of human foreskin fibroblasts induced by UVA irradiation by inhibiting the expression of cell cycle inhibitors and reducing the level of mitochondrial ROS.2.Metformin alleviated the oxidative stress level of UVA-irradiated human foreskin fibroblasts possibly through the P62-Keap1-Nrf2 signaling pathway.3.Metformin can effectively reverse the photoaging of guinea pig skin caused by UVA irradiation. |
