Abstract:

Objective To investigate the effect of Yaoshu Zhuyu Fang on the regulation of the microRNA-17-5P (miR-17-5P)/murine double minute 2 (MDM2)/p53 axis in the proliferation and apoptosis of rat intervertebral disc annulus fibrosus cells, and its potential molecular mechanism. Methods Intervertebral disc annulus fibrosus tissues were obtained from 8-week-old SPF-grade male SD rats, and annulus fibrosus cells were isolated and obtained by enzyme digestion and mechanical dispersion. Annulus fibrosus cells were divided into 6 groups: Group C was the blank control group, in which annulus fibrosus cells were not treated with interleukin-1β (IL-1β) but were cultured in RPMI 1640 complete medium. Group β was the degeneration model group constructed by treating annulus fibrosus cells with 10 ng/mL IL-1β for 24 h. Group β+B was the IL-1β + blank serum group, in which annulus fibrosus cells were first treated with IL-1β to construct the degeneration model, then treated with RPMI 1640 medium containing 5% blank serum for 24 h. Group β+W was the IL-1β + Yaoshu Zhuyu Fang-containing serum group, in which annulus fibrosus cells were first treated with IL-1β to construct the degeneration model, then treated with RPMI 1640 medium containing 5% Yaoshu Zhuyu Fang-containing serum for 24 h. Group β+I was the IL-1β + miR-17-5P inhibitor group, in which annulus fibrosus cells were first treated with IL-1β to construct the degeneration model, then transfected with miR-17-5P inhibitor. Group β+I+W was the IL-1β + miR-17-5P inhibitor + Yaoshu Zhuyu Fang-containing serum group, in which annulus fibrosus cells were first treated with IL-1β to construct the degeneration model, then transfected with miR-17-5P inhibitor, and finally treated with RPMI 1640 medium containing 5% Yaoshu Zhuyu Fang-containing serum for 24 h. CCK-8 assay was used to detect cell survival rate. Flow cytometry was used to detect cell apoptosis. Real-time quantitative PCR was used to detect the expression levels of miR-17-5P, MDM2 mRNA, and p53 mRNA in cells. Western blotting was used to detect the protein expression levels of MDM2 and p53 in cells. Dual-luciferase reporter system was used to analyze the targeting relationship between miR-17-5P and MDM2. Results Compared with Group C, Group β showed a significant decrease in cell survival rate (P<0.001), a significant increase in cell apoptosis rate (P<0.001), significantly increased expression of miR-17-5P, p53 mRNA, and p53 protein (P<0.001), and significantly decreased expression of MDM2 mRNA and protein (P<0.001). Compared with Group β, Group β+W, Group β+I, and Group β+I+W showed significantly increased cell survival rate, significantly decreased apoptosis rate, significantly decreased expression of miR-17-5P, p53 mRNA, and p53 protein, and significantly increased expression of MDM2 mRNA and protein (P<0.001). Moreover, changes in the above indicators were greater in Group β+I+W (P<0.001). Circular RNA Interactome predicted that miR-17-5P had specific binding sites with the 3' untranslated region (3'UTR) of MDM2. Transfection of miR-17-5P mimic significantly reduced the luciferase expression level of co-transfected luciferase reporter plasmid containing wild-type MDM2 3'UTR (P<0.05), but had no significant effect on luciferase expression in cells co-transfected with luciferase reporter plasmid containing mutant MDM2 3'UTR (P>0.05). Conclusion Yaoshu Zhuyu Fang down-regulates the expression of miR-17-5P, promotes the synthesis of MDM2 protein, thereby down-regulates p53, promotes proliferation, and inhibits the apoptosis of rat intervertebral disc annulus fibrosus cells.

Key words: Intervertebral disc degeneration, Yaoshu Zhuyu Fang, microRNA-17-5P, Cell proliferation, Cell apoptosis, Rats