TGF-β-miR-34a-CCL22 Signaling-Induced Treg Cell Recruitment Promotes Venous Metastases of HBV-Positive Hepatocellular Carcinoma

SummaryPortal vein tumor thrombus (PVTT) is strongly correlated to a poor prognosis for patients with hepatocellular carcinoma (HCC). In this study, we uncovered a causative link between hepatitis B virus (HBV) infection and development of PVTT. Mechanistically, elevated TGF-β activity, associated with the persistent presence of HBV in the liver tissue, suppresses the expression of microRNA-34a, leading to enhanced production of chemokine CCL22, which recruits regulatory T (Treg) cells to facilitate immune escape. These findings strongly suggest that HBV infection and activity of the TGF-β-miR-34a-CCL22 axis serve as potent etiological factors to predispose HCC patients for the development of PVTT, possibly through the creation of an immune-subversive microenvironment to favor colonization of disseminated HCC cells in the portal venous system.

► HBV positive status predisposes HCC patients to develop PVTT
► MiR-34a expression inversely correlates with TGF-β activity and PVTT
► HBV-induced TGF-β recruits Treg cells via suppression of miR-34a and induction of CCL22
► TGF-β-miR-34a-CCL22 promotes tumor growth and metastasis via changing microenvironment