Abstract: Objective To investigate the role of long non-coding RNA LINC00319 in the occurrence and developmentof keloids, as well as its underlying molecular mechanisms. 
Methods A total of 18 patients with clinically diagnosed keloids were enrolled from the Affiliated Hospital of Chengde Medical College from February 2024 to February 2025. Keloid tissues and adjacent normal skin tissues were collected, and primary fibroblasts were isolated to obtain keloid fibroblasts (KFs) and normal dermal fibroblasts (NFs). The expression levels of LINC00319 and miR-199a-5p in tissues and cells were determined by quantitative real-time PCR (qRT-PCR). Small interfering RNA was used to silence LINC00319 expression in KFs, and the silencing efficiency was verified using qRT-PCR. The effects of LINC00319 silencing on cell proliferation were evaluated using the CCK-8 assay, while apoptosis was assessed by flow cytometry. The targeted binding relationship between LINC00319 and miR-199a-5p was confirmed by dual-luciferase reporter assay. In addition, qRT-PCR was performed to determine the regulatory effect of LINC00319 knockdown on miR-199a-5p expression. KFs were co-transfected with si-LINC00319 and miR-199a-5p inhibitor to assess the effects on cellular proliferative activity. 
Results Compared with normal tissues (0.76±0.31) and NFs (0.84±0.14), the expression level of LINC00319 was significantly elevated in keloid tissues (6.29±4.07) and KFs (4.90±0.37) (P＜0.001). Its expression was positively correlated with the Vancouver Scar Scale score (r=0.794, P＜0.001). Following LINC00319 knockdown, the optical density values of KFs at 24 h, 48 h, and 72 h (0.34±0.01, 0.50±0.01, and 0.59±0.01) were significantly lower than those in the control group (0.49±0.01, 0.68±0.01, and 0.80±0.01), and significant differences were observed in interaction between groups, time points, and time points between groups (P＜0.05). The apoptosis rate in the si-LINC00319 group was significantly increased compared with the control group ［(30.58±2.48)% vs. (9.69±1.22)%］ (P＜0.001). Dual-luciferase reporter assay confirmed a direct binding interaction between LINC00319 and miR-199a-5p. In KFs, the expression level of miR-199a-5p (0.68±0.02) was significantly lower than that in the control group (1.09±0.07) (P＜0.001), whereas silencing LINC00319 markedly elevated miR-199a-5p expression compared with the si-NC group ［(1.81±0.05) vs. (0.94±0.06)］ (P＜0.001). Rescue experiments demonstrated that silencing LINC00319 significantly inhibited the proliferative activity of KFs. However, under co-transfection with miR-199a-5p inhibitor, the optical density values at 24 h, 48 h, and 72 h (0.43±0.01, 0.68±0.02, 0.79±0.02) were significantly higher than those in the si-LINC00319 group (0.34±0.01, 0.49±0.01, 0.59±0.01)(P＜0.001). Statistical analysis indicated significant differences in interaction between groups, time points, and time points between groups (P＜0.05).
Conclusion LINC00319 facilitates the occurrence and development of keloids by negatively regulating miR-199a-5p. 

Key words: keloid, LINC00319, miR-199a-5p