Mechanisms of Post-Transplant Hepatocellular Carcinoma Recurrence Under Tacrolimus-Induced Immunosuppression
Purpose:Liver transplantation (LT) enhances survival in hepatocellular carcinoma (HCC), but iatrogenic immunosuppression leads to graft recurrence in about 15% of recipients. We aimed to elucidate mechanisms of post-transplant HCC recurrence under immunosuppression and to develop strategies for its control and prevention.Experimental Design:Paired formalin-fixed paraffin-embedded samples were collected from five patients, including the primary tumor site (LT) and the recurrence site (re-hepatectomy). After evaluating the hematoxylin and eosin-stained sections, single-cell spatial multi-omics analysis was performed on one case. The findings were validated by immunohistochemistry and immunofluorescence in the same case cohort, along with in vitro and in vivo experiments.Results:Intrasinusoidal tumor progression was observed in non-tumor regions adjacent to the tumor margin at recurrent sites. Spatial analysis, focusing on this feature, identified CXCL12-CXCR4 signaling as the most significant contributor at the recurrent site, with its cell types originating from liver sinusoidal endothelial cells (LSECs) and cancer-associated fibroblasts (CAFs). These factors were not present in the primary tumor, indicating they are specific to recurrence. Using immunohistochemistry and immunofluorescence, the expression and colocalization of both signals at the recurrent site were confirmed. In vitro, FK506 treatment enhanced the migration of CXCR4+CAFs toward LSECs, an effect inhibited by co-treatment with plerixafor. Additionally, in a syngeneic mouse model of liver metastasis, The FK506-induced metastatic increase was attenuated when plerixafor was administered concurrently.Conclusions:The CXCL12+LSEC-CXCR4+CAF interaction is vital in promoting post-transplant HCC recurrence. Blocking this axis could be a promising strategy for treating and preventing recurrence while preserving graft-protective immunosuppression.