The inhibitory effect of Wnt antagonist Dickkopf-1 (Dkk-1) on transdifferentiation of renal tubular epithelial cells / 解放军医学杂志

ABSTRACT

Objective To investigate the effects of the Wnt antagonist Dickkopf-1(Dkk-1) on epithelial mesenchymal transdifferentiation in human proximal tubular epithelial cells induced by transforming growth factor-β1 (TGF-β1). Methods Human proximal tubular epithelial cells (HKC) were cultured in vitro and divided into three groups as follows control group, TGF-β1 group, and TGF-β1+Dkk-1 group. The cells in the control group underwent routine culture with medium containing 10% fetal calf serum. For the TGF-β1 group, TGF-β1 (final concentration 20ng/ml) was added into the routine culture medium. For TGF- β1+Dkk-1 group, TGF-β1 (final concentration 20ng/ml) and Dkk-1(final concentration 100ng/ml) were added at the same time. After cultured for 48h, we performed morphologic observation using an inverted contrast microscope. RT-PCR and Western blotting were adopted to detect the expressions of Wnt4, β-catenin, E-cadherin, and α-SMA mRNA. E-cadherin and α-SMA expressions were detected by cell immunofluorescence. Results Compared with control group, the mRNA expression of Wnt4 and the protein expression of Wnt4 were significantly increased in TGF-β1 and TGF-β1+Dkk-1 groups (P0.05). There was no obvious difference between each group in mRNA expression of β-catenin (P>0.05). The β-catenin protein exhibited low expression in control group, whereas the expression significantly increased in TGF-β1 group. The expression of β-catenin in TGF-β1+Dkk-1 group was lower than that in TGF-β1 group (P0.05). The mRNA and protein expression of E-cadherin were high in control group, but were significantly decreased in TGF-β1 group. Their expressions in the TGF-β1+Dkk-1 group were increased compared with that in TGF-β1 group (P0.05). The mRNA and protein expression of α-SMA were decreased in control and TGF-β1+Dkk-1 groups, compared with TGF-β1 group (P<0.05). Immune fluorescent staining showed that the expression of E-cadherin and α-SMA were consistent with the results of RT-PCR and Western blotting. Conclusion Wnt antagonist Dickkopf-1(Dkk-1) can inhibit epithelial mesenchymal transdifferentiation induced by TGF-β1.