OBJECTIVETo screen out related microRNAs in keloid tissue, and identify their effect on the proliferation of keloid fibroblasts.

METHODS8 cases of keloid tissue and 8 cases of normal skin tissue were collected as specimens. The differently expressed miRNA in keloid tissue from normal skin tissue were screened out with gene chip( Exiqon company), which was validated with quantitative real-time PCR. Then miRNA mimics was transfected into keloid fibroblasts line to stimulate high expression of mature miRNA in cells. The effect on the proliferation of fibroblasts in keloid was tested by Edu.

RESULTS(1) A total of 17 differently expressed microRNAs were found, including miR-199a-5p. (2) The expression of miR-199a-5p had been verified by qRT-PCR to be down-regulated in keloid, which was consistent with the result of array. (3) The positive rate of EdU in miR-199a-5p mimics transfected group and negative control group was (20.72 +/- 2.50)% and (27.68 +/- 4.92)%, respectively. The proliferative rate of keloid fibroblasts turned down in miR-199a-5p-transfected group (t = 2.183, P = 0.047). Besides that, the cell cycle changed after transfection. The percentage of S and G2/M phase in miR-199a-5p mimics transfected group was 33.93 +/- 1.30 and 10.87 +/- 0.80, respectively, while it was 31.39 +/- 0.79 and 9.27 +/- 0.46 in negative control group, and the difference was statistically significant.

CONCLUSIONS(1) The miRNA expression profile is different between keloid and normal skin; (2) The expression of miR-199a-5p is down-regulated in keloid and miR-199a-5p can affect the cell cycle and suppress proliferation of keloid fibroblasts. It indicateds that miR-199a-5p may be involved in regulating fibroblastic proliferation.