The multi-kinase inhibitor pazopanib targets hepatic stellate cell activation and apoptosis alleviating progression of liver fibrosis.

Tyrosine kinase inhibitors have been emerged recently as an effective therapy against liver fibrosis. The current study was designed to test a potential anti-fibrotic effect of the multi-targeted receptor tyrosine kinase inhibitor pazopanib. Carbon tetrachloride (CCl4; 1 mL/kg) was injected intraperitoneally (i.p.) twice/week for 8 weeks. Pazopanib (10 and 30 mg/kg, i.p.) was administered three times/week at the beginning of week 5. Levels of liver function biomarkers (alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin, and total bilirubin), malondialdehyde, transforming growth factor-β1 (TGF-β1), caspase-3, factor-related apoptosis (FAS), vascular endothelial growth factor (VEGF) receptor-1, and pigment endothelial derived factor (PEDF) were measured. The tissue level of the inflammatory cytokines IL-6 and tumor necrosis factor-α (TNF-α) were assigned. Fibrotic area was measured by morphometry and expression of alpha-smooth muscle actin (α-SMA), caspase-3, platelet-derived growth factor (PDGF) receptor-β, and matrix metalloproteinase-2 (MMP-2) was scored immunohistochemically. Hepatic expression of collagen-1-alpha-1 (Col1A1) and tissue inhibitor metalloproteinase-1 (TIMP-1) mRNA were assigned by RT-qPCR. Injection of CCl4 resulted in marked collagen deposition, necroinflammation, and fibrosis (2.67%). Pazopanib in a dose of 30 mg/kg improved liver function, reduced fibrosis (1.48%), and decreased significantly (P < 0.01) liver expression of malondialdehyde, TGF-β1, IL-6, TNF-α, Col1A1, TIMP-1, α-SMA, MMP-2, PDGF receptor-β, and VEGF receptor-1. Additionally, the apoptotic markers (caspase-3, FAS) and the anti-angiogenic factor PEDF were upregulated significantly (P < 0.05). Pazopanib at a certain dose level can halt liver fibrosis progression through modulating inflammatory cytokines, suppressing stellate cell activity, inducing apoptosis, and potentially regulating angiogenesis.