The ROCK inhibitor, thiazovivin, inhibits human corneal endothelial-to-mesenchymal transition/epithelial-to-mesenchymal transition and increases ionic transporter expression

Corneal diseases exhibit a high prevalence and are prone to cause blindness; furthermore, maintaining the morphology and ionic transporter expression in corneal endothelial cells (CECs) is crucial for treatment of these diseases. This study aimed to investigate the effects of the novel Rho associated coiled-coil containing protein kinase (ROCK) inhibitor, thiazovivin (2,4-disubstituted thiazole, TZV), on human corneal endothelial-to-mesenchymal transition/epithelial-to-mesenchymal transition (EndMT/EMT), cell morphology, junction proteins and ionic transporter expression in human CECs (HCECs) in vitro and then to clarify the mechanisms of action of TZV. In the present study, primary HCECs were cultured in vitro and passaged. The expression levels of adhesion proteins (E-cadherin and N-cadherin), the EndMT/EMT marker, α smooth muscle actin (α-SMA), the tight junction protein, Zonula occludens-1 (ZO-1), and the ionic transporter, Na(+)/K(+)-ATPase, were detected by immunofluorescence. The proliferative ability of the HCECs was determined by CCK-8 assay. The mRNA expression of the EndMT/EMT-inducing gene, Snail, was examined by RT-PCR. The protein expression levels of ROCK1/2 were evaluated by western blot analysis. The HCECs were cultured with TZV at various concentrations (2, 4, or 6 µM) for different periods of time (24 or 48 h). We found that the the cell states of the HCECs co-cultured with 4 µM TZV for 48 h reached the optimum, and corneal EndMT/EMT was inhibited, as evidenced by the significantly upregulated expression of ZO-1 and E-cadherin, and the markedly downregulated expression of N-cadherin and α-SMA. Furthermore, the cells exhibited a normal, tightly connected hexagonal or pentagonal morphology. Additionally, the protein expression of ROCK1/2 and the mRNA expression of Snail were significantly decreased. However, there was no significant difference between the TZV-treated and the control groups as regards HCEC proliferative ability. These findings suggested that the ROCK inhibitor, TZV (4 µM), was effective in improving the morphology, cell junctions and ionic transporter expression of HCECs by inhibiting EndMT/EMT, but had no effect on HCEC proliferation.