Abstract: BACKGROUND: At present, numerous studies have shown that miRNA is involved in the occurrence and development of hypertrophic scars and STAT1 is involved in the proliferation of scar fibroblasts. It is speculated that miR-382-3p may also be related to the occurrence and development of hypertrophic scars.
OBJECTIVE: To investigate the mechanism of miR-382-3p on the proliferation of human hypertrophic scar fibroblasts.
METHODS: Hypertrophic scar and normal skin of the same individual were collected from the Department of Burn Plastic Surgery, General Hospital of Ningxia Medical University, and human hypertrophic scar fibroblasts and human normal skin fibroblasts were then extracted. Cell transfection was conducted as follows: (1) the cells were divided into control group (no treatment), miR-382-3p negative control group, and miR-382-3p overexpression group; (2) the cells were divided into control group (no treatment), STAT1 interference control group (si-NC) and STAT1 interference groups (si-STAT1-1, si-STAT1-2, si-STAT1-3). Hematoxylin-eosin staining was used to identify normal skin and hypertrophic scar, and immunofluorescence was used to identify fibroblasts. Quantitative real-time PCR was applied to detect the mRNA expression of miR-382-3p, STAT1, proliferating cell nuclear antigen (PCNA) and cyclin-dependent kinase inhibitor (p27). Western blot assay was performed to detect the protein expressions of STAT1, PCNA and p27. Cell counting kit-8 and EdU were used to detect cell proliferation activity and proliferation level. Targetscan was used to predict the downstream target genes of miR-382-3p and dual luciferase was used to verify the binding of miR-382-3p to STAT1.
RESULTS AND CONCLUSION: Compared with normal skin and normal skin fibroblasts, miR-382-3p was lowly expressed in hypertrophic scar and hypertrophic scar fibroblasts (tissue: P < 0.01, cell: P < 0.01), and STAT1 was highly expressed in hypertrophic scar and hypertrophic scar fibroblasts (mRNA level in tissue: P < 0.01, protein level in tissue: P < 0.01; mRNA level in cells: P < 0.01, protein level in tissue: P < 0.01). After overexpression of miR-382-3p, the cell proliferation ability was weakened (P < 0.05), the number of EdU positive cells was decreased (P < 0.01), the expression of PCNA was decreased (mRNA: P < 0.01, protein: P < 0.05), and the expression of p27 was increased (mRNA: P < 0.05, protein: P < 0.05). miR-382-3p could target and regulate the expression of STAT1 (P < 0.01), and overexpression of miR-382-3p could reduce the expression of STAT1 (mRNA: P < 0.01, protein: P < 0.01). Interference with STAT1 reduced the expression of PCNA (P < 0.05), increased the expression of p27 (P < 0.05), and reduced the number of EdU positive cells (P < 0.01). To conclude, miR-382-3p could inhibit the proliferation of hypertrophic scar fibroblasts by inhibiting the expression of STAT1, which provides a certain theoretical basis for identifying effective targets for the treatment of hypertrophic scars.

Key words: miR-382-3p, STAT1, PCNA, p27, hypertrophic scar, normal skin, fibroblast, proliferation