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B16 cells were seeded in 96-well plates and incubated with various concentrations of fasudil for 24h. The cell inhibitory rate was measured using an MTT assay. Fasudil inhibited B16 cell proliferation in a dose-dependent manner, and the IC50 for 24h of fasudil in B16 cells was 71 {plus minus} 5.8μM.

(A) HE staining of tissue section. A vessel formed with elongated endothelial cells was showed by a red arrow, moreover, the vessel lack of endothelial cells nearby was pointed out by a yellow arrow. Original magnification, ×400. (B) Plenty of blood sinusoids were observed in the CD31/PAS dual-stained sections. Original magnification, ×100. (C) Endothelial cell lined-blood vessels containing CD31-positive immunoreactivity (dark brown) . (D) A VM structure were strictly defined as PAS-positive (purple magenta) CD31-negative. Detached tumor cells (black arrows) reached the blood stream, and it is suggested that VM networks facilitate tumor metastasis. Original magnification, ×400.

ObjectivesDysregulated chondrocyte metabolism is closely associated with the pathogenesis of osteoarthritis (OA). Suppressing chondrocyte catabolism to restore cartilage homeostasis has been extensively explored, whereas far less effort has been invested toward enhancing chondrocyte anabolism. This study aimed to repurpose clinically approved drugs as potential stimulators of chondrocyte anabolism in treating OA.MethodsScreening of a Food and Drug Administration-approved drug library; Assays for examining the chondroprotective effects of digoxin in vitro; Assays for defining the therapeutic effects of digoxin using a surgically-induced OA model; A propensity-score matched cohort study using The Health Improvement Network to examine the relationship between digoxin use and the risk of joint OA-associated replacement among patients with atrial fibrillation; identification and characterisation of the binding of digoxin to low-density lipoprotein receptor-related protein 4 (LRP4); various assays, including use of CRISPR-Cas9 genome editing to delete LRP4 in human chondrocytes, for examining the dependence on LRP4 of digoxin regulation of chondrocytes.ResultsSerial screenings led to the identification of ouabain and digoxin as stimulators of chondrocyte differentiation and anabolism. Ouabain and digoxin protected against OA and relieved OA-associated pain. The cohort study of 56 794 patients revealed that digoxin use was associated with reduced risk of OA-associated joint replacement. LRP4 was isolated as a novel target of digoxin, and deletion of LRP4 abolished digoxin’s regulations of chondrocytes.ConclusionsThese findings not only provide new insights into the understanding of digoxin’s chondroprotective action and underlying mechanisms, but also present new evidence for repurposing digoxin for OA.

The aim of this study was to investigate the biologic role of the Rho kinase inhibitor fasudil in the vasculogenic mimicry (VM) of B16 mouse melanoma cells. It was previously reported that RhoA plays a critical role in angiogenesis by coordinating endothelial cell cytoskeleton remodeling and promoting endothelial cell motility. Although RhoA has been implicated in the regulation of angiogenesis, little has been described regarding its control of these tumor cell–lined channels. In this study, we established an in vitro model of VM using 3-dimensional cell culturing of mouse B16 melanoma cells and studied VM in vivo by transplanting B16 cells into C57/BL mice. Next, we explored the effect of RhoA and Rho-associated, coiled-coil containing protein kinase (ROCK) on VM formation using the Rho kinase inhibitor fasudil. We provide direct evidence that fasudil leads to reduced vascular-like channels in Matrigel. Additional experiments suggested that fasudil prevents both initial cellular architecture changes and cell migration in vitro. Finally, we provide in-depth evidence for the underlying mechanisms of fasudil-induced VM destruction using the Rho-GTPase agonist lysophosphatidic acid. In vivo studies revealed that fasudil reduced B16 melanoma cell xenograft tumor growth without causing significant toxicity in mice. Fasudil-treated tumors also displayed fewer VM channels. These results suggest that fasudil may be an emerging therapeutic option for targeting cancer VM. Mol Cancer Ther; 14(7); 1582–90. ©2015 AACR.