PTPRO-associated hepatic stellate cell activation plays a critical role in liver fibrosis.

BACKGROUND/AIMS: PTPRO (protein tyrosine phosphatase, receptor type O) is implicated in diverse physiological and pathological processes in cancer and hepatic ischemia/reperfusion injury, although little is known about its role in hepatic fibrosis.

METHODS: Here, by using genetically deficient mice, we reported that PTPRO knockout (PTPRO(-/-)) significantly attenuated liver injury, release of inflammatory factors, tissue remodeling, and liver fibrosis in two experimental mouse models of fibrogenesis induced by bile-duct ligation or carbon tetrachloride administration.

RESULTS: However, we proved that PTPRO expression was strongly downregulated in clinical and experimental liver fibrosis specimens. Further investigations revealed that stimulation of primary hepatic stellate cells (HSCs) and hepatocytes with specific activator platelet-derived growth factor (PDGF)-BB increased PTPRO transcription in HSCs but had the opposite effect in primary hepatocytes. More importantly, synthetic short hairpin RNA targeting PTPRO significantly neutralized PDGF-BB-induced HSC proliferation and myofibroblast marker expression through downregulated phosphorylation of extracellular signal-regulated kinase (ERK) and AKT.

CONCLUSION: These observations confirm that PTPRO plays a critical role in liver fibrogenesis by affecting PDGF signaling in HSC activation and might be developed into a feasible therapeutic approach for the treatment of chronic fibrotic liver diseases.