PARP-1 promotes tumor recurrence after warm ischemic liver graft transplantation via neutrophil recruitment and polarization

Poly (ADP-ribose) polymerase 1 (PARP-1) is a crucial contributor to exacerbate ischemia and reperfusion (IR) injury and cancer process. However, there is little research into whether PARP-1 affects the hepatocellular carcinoma (HCC) recurrence after liver transplantation. In this study, we investigated the influence of PARP-1 on hepatic neutrophil mobilizing and phenotype shifting which may lead to HCC recurrence after liver transplantation. We found that rats received the grafts with warm ischemic injury had higher risk of HCC recurrence, which was markedly prevented by pharmacological inhibition of PARP-1 after liver transplantation. In mouse models, the up-regulation of PARP-1 was closely related to the greater tumor burden and increased hepatic susceptibility to recurrence after IR injury. The reason was that high hepatic PARP-1 led to increased liver CXCL1 levels, which in turn promoted recruitment of neutrophils. Both blocking CXCL1/CXCR2 signaling pathway and depleting neutrophils decreased tumor burden. Moreover, these infiltrating neutrophils were programmed to a proangiogenic phenotype under the influence of PARP-1 in vivo after hepatic IR injury. In conclusion, IR-induced PARP-1 up-regulation increased the hepatic recruitment of neutrophils through regulation of CXCL1/CXCR2 signaling and polarized hepatic neutrophils to proangiogenic phenotype, which further promoted HCC recurrence after transplantation.