Objective  To investigate the effect of microRNA-146a-5p (miR-146a-5p) on high glucose-induced injury of renal tubular epithelial cells by regulating high mobility group A2 (HMGA2).

Methods  Human renal tubular epithelial cells (HK-2) were cultured in vitro and divided into different groups according to various treatment methods: normal control group (Con group), high glucose group (HG group), HG+miR-146a-5p group, HG+si-HMGA2 group, HG+miR-146a-5p+pcDNA-HMGA2 group, miR-NC group, miR-146a-5p group, anti-miR-NC group, and anti-miR-146a-5p group. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression levels of miR-146a-5p and HMGA2 mRNA in each group. A dual-luciferase reporter assay was employed to verify the targeting relationship between miR-146a-5p and HMGA2. Western blot was utilized to detect the expression levels of cleaved-caspase3, cleaved-caspase9, and HMGA2 protein in each group. Flow cytometry was applied to determine the apoptosis rate of cells in each group. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory factorsinterleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8)in each group. The levels of oxidative stress indicatorscatalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA)in each group were also measured.

Results  A nucleotide sequence complementary to miR-146a-5p was found in the 3′-untranslated region (3′-UTR) of HMGA2 . The expression level of HMGA2 protein in the miR-146a-5p group was lower than that in the miR-NC group, while was higher in the anti-miR-146a-5p group than that in the anti-miR-NC group (P < 0.05). The total apoptosis rate, early apoptosis rate, late apoptosis rate, and the levels of cleaved-caspase3 protein, cleaved-caspase9 protein, HMGA2 mRNA, HMGA2 protein, TNF-α, IL-6, IL-8, and MDA in the HG group were higher than those in the Con group, whereas the levels of miR-146a-5p, CAT, and SOD were lower (P < 0.05). In the HG+miR-146a-5p group, these indicators showed opposite trends compared to the HG group (P < 0.05). Similarly, in the HG+si-HMGA2 group, the total apoptosis rate, early apoptosis rate, late apoptosis rate, and the levels of cleaved-caspase3 protein, cleaved-caspase9 protein, HMGA2 mRNA, HMGA2 protein, TNF-α, IL-6, IL-8, and MDA were lower than those in the HG group, while the levels of CAT and SOD were higher (P < 0.05). In the HG+miR-146a-5p+pcDNA-HMGA2 group, the trends of these indicators were consistent with those between the HG group and the HG+miR-146a-5p group, showing statistically significant differences when compared to the HG+miR-146a-5p group(P < 0.05).

Conclusion  MiR-146a-5p may play a regulatory role in high glucose-induced injury of renal tubular epithelial cells by targeting HMGA2.