ABSTRACT
Objective To assess the effect of silent mating type information regulation 2 homolog 6 (SIRT6) on migratory and proliferative activity of skin fibroblasts in the elderly,and to explore their mechanisms.Methods Circumcised foreskins were obtained from patients of different ages in Department of Urologic Surgery,Second Hospital of Shanxi Medical University,including 8 elderly patients and 8 young patients.Human skin fibroblasts were isolated from the foreskin tissues by using a collagenase digestion method.Western blot analysis was performed to determine the expression of SIRT6 and phosphorylated p65 (p-p65) in human skin fibroblasts in different age groups,scratch assay to evaluate cell migratory activity,and cell counting kit-8 (CCK8) assay to assess cellular proliferative activity.Skin fibroblasts in the elderly group were divided into 2 groups:SIRT6 group transfected with a lentiviral vector overexpressing SIRT6,and control group transfected with an empty lentiviral vector.Then,the cell migratory and proliferative activity as well as p-p65 expression were measured by the above methods,and the mRNA expression of type Ⅰ and Ⅲ collagens,and integrin subunits α3,α5 and β1 was determined by real-time PCR in the SIRT6 group and control group.Statistical analysis was carried out with GraphPad Prism 5 software by using t test for comparison between 2 groups.Results Compared with the young group,the elderly group showed significantly decreased SIRT6 expression in skin fibroblasts (0.434 ±0.179 vs.1.000 ± 0.067,t =3.040,P =0.012),migration rate (43.81％ ± 18.84％ vs.94.63％ ± 12.32％,t =5.903,P =0.003)and cellular proliferative activity at 24 and 48 hours (both P ＜ 0.05),but significantly increased p-p65 expression (1.694 ± 0.148 vs.1.000 ± 0.093,t =2.949,P =0.015).Compared with the control group,the SIRT6 group showed significantly decreased p-p65 expression (P ＜ 0.05),but significantly increased migratory and proliferative activity (both P ＜ 0.05),and elevated mRNA expression of type Ⅲ collagen and integrin subunits oα3,α5 and β1 (all P ＜ 0.05).Conclusion SIRT6 can improve the migratory and proliferative activity of human fibroblasts in the elderly,possibly by inhibiting the nuclear factor-κB pathway.