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This study aimed to clarify the oxidative damage in human skin fibroblasts (HSF) treated with trimethylamine oxide (TMAO) and to elucidate its pro-aging effect in skin cells in terms of antioxidant indicators, levels of inflammatory cytokines, levels of collagen and matrix metalloproteinases, and mRNA expression of related genes. The results showed that TMAO treatment significantly increased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and decreased the content of reduced glutathione, superoxide dismutase (SOD) activity, and total antioxidant capacity (TAC) in HSF cells (P < 0.05). TMAO treatment was found to significantly elevate the mRNA levels of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and matrix metalloproteinase-1 (MMP-1), and decrease the mRNA transcript levels of collagen synthesis-related genes and the inducible nitric oxide synthase (iNOS) gene by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). Western blot analysis showed that the protein expression level of phosphorylated p65 (p-p65) significantly increased (P < 0.05). Vitamin C (VC) was able to protect against TMAO-induced oxidative stress in HSF cells, and reduce inflammation and collagen loss. These results indicated that TMAO can produce oxidative stress in HSF cells, which may activate the signaling pathway of nuclear factor kappa-B (NF-κB), promote NF-κB phosphorylation in HSF cells, induce inflammatory responses, reduce collagen synthesis, and accelerate collagen degradation, thus possibly promoting skin cell aging.

Objective To investigate the effect and mechanism of GPRC5A (G protein-coupled receptor family C, member 5, group A) gene on the migration and invasion of osteosarcoma cell line 143B. Methods Differentially expressed genes in metastatic tumors were screened out from the GSE32981 data set, and the survival analysis of the differentially expressed genes was performed in combination with the TCGA database. CCK8 experiment, scratch experiment and Transwell invasion experiment were carried out to detect the effect of GPRC5A knockdown or overexpression on osteosarcoma cell proliferation, migration and invasion. Western blot and RT-qPCR detected the effect of GPRC5A knockdown or over-expression on protein and mRNA levels of EMT related genes. Results The expression of 299 genes was changed in metastatic osteosarcoma, and 37 genes closely related to the survival of osteosarcoma patients were further screened out combined with TCGA database. The results of cell experiments showed that GPRC5A had no effect on the proliferation of osteosarcoma cells, but GPRC5A over-expression could significantly promote osteosarcoma cells migration and invasion(P＜0.05). GPRC5A overexpression promoted the expression of EMT-related proteins N-Cad and Vim, and inhibited the expression of E-Cad(P＜0.05). Conclusions GPRC5A is closely related to the survival of osteosarcoma patients and may promote the migration and invasion of osteosarcoma cells by inducing EMT, so it is believed to be a potential target for anti-osteosarcoma metastasis drugs.