Gadd45a gene silencing by RNAi promotes cell proliferation and inhibits apoptosis and senescence in skin squamous cell carcinoma through the p53 signaling pathway.

Skin squamous cell carcinoma (SCC) is generally considered as nonaggressive lesions and mainly caused by ultraviolet (UV) radiation. Gadd45a is a key component protecting skin against UV-induced tumors. For that, the study aims to investigate the mechanism of Gadd45a gene silencing on cell proliferation, apoptosis, and senescence in nude mice with skin SCC through the p53 signaling pathway. Healthy nude mice was collected as the normal group and 40 nude mouse models of skin SCC were successfully established as the model group, which were sub-divided into five groups. The incidence, size, and weight of SCC tumor of nude mice were observed. The mRNA expression of Gadd45a, Cyclin B1, MMP-2, Bcl-2, and Bax were determined by RT-qPCR. Cell viability, cell cycle and apoptosis, cell senescence were detected by MTT assay, flow cytometry, and β-galactosidase staining, respectively. The levels of inflammatory factors and vascular endothelial growth factor (VEGF) were detected by using ELISA. The protein expression rate of mutant p53 was detected by immunohistochemistry. Mice transfected with siGadd45a showed increased tumor incidence, size, and weight. Cells transfected with siGadd45a showed decrease in expression of Gadd45a and Bax; and increase in expression of Cyclin B1, MMP-2, and Bcl-2, expression of mutant p53, IL-1α, IL-1β, IL-6, TNF-α, and VEGF. Cell apoptosis and senescence were inhibited, while cell viability and proliferation were promoted after siGadd45a treatment. The results reveal that Gadd45a silencing increases tumor cell proliferation and reduces apoptosis and senescence through the p53 signaling pathway in skin SCC.