PMID: Folia Histochem Cytobiol. 2021 Dec 2. Epub 2021 Dec 2. PMID: 34852178 Abstract Title: Tanshinone IIA attenuates high glucose-induced epithelial-to-mesenchymal transition in HK-2 cells through VDR/Wnt/β-catenin signaling pathway. Abstract: INTRODUCTION: The progression of diabetic kidney disease (DKD) is closely related to renal tubular epithelial-to-mesenchymal transition (EMT) and tubulointerstitial fibrosis. Tanshinone IIA (TSIIA), extracted from a traditional Chinese medicine named Salvia miltiorrhiza, has been proved to have anti-fibrosis effects. The aim of this study was to investigate the effect of TSIIA on high glucose-induced EMT in human proximal tubular cells (HK-2 cells) and its possible mechanism.MATERIAL AND METHODS: The proliferation of cells exposed to different concentrations of glucose was measured by light microscopy and CCK-8 test. The cells were stimulated with 30 mM glucose and different concentrations of TSIIA (5μM or 10 μM) for 48 h. Vitamin D receptor (VDR)-siRNA was used to transfect cells, and high glucose and TSIIA treatment were further used to treat cells. The expression of alpha smooth muscle actin (α-SMA) mRNA was detected by qPCR to ensure successful induction of EMT, and the expression of VDRmRNA was detected by qPCR to ensure successful transfection of VDR-siRNA. Protein expression of α-SMA, E-cadherin, VDR, β-catenin and glycogen synthase kinase 3β (GSK-3β) was detected by Western blot analysis.RESULTS: The results showed that high glucose concentration inhibited cell proliferation and promoted EMT in HK-2 cells. TSIIA could reverse high glucose-induced EMT by increasing the level of VDR protein and inhibiting the levels ofβ-catenin and GSK-3β proteins suggestive of a negative correlation between VDR and the Wnt/β-catenin pathway. After VDR-siRNA transfection and incubation of cells at high glucose concentration, the inhibitory effect of VDR on the expression of β-catenin and GSK-3β of Wnt pathway was suppressedand the β-catenin pathway was activated. When VDR level was restored by TSIIA, the inhibitory effect of VDR on the pathway was also restored and the activation of the pathway was suppressed.CONCLUSIONS: TSIIA was able to attenuate high glucose-induced EMT in HK2 cells by up-regulating VDR levels, which might be related to the inhibitory effect of VDR on the Wnt pathway.
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