The significance of acute phase small-for-size graft injury on tumor growth and invasiveness after liver transplantation.

OBJECTIVE: To test the hypothesis that acute phase small-for-size graft injury may promote late phase tumor recurrence after liver transplantation. SUMMARY BACKGROUND DATA: Living donor liver transplantation may provide the substantial intention-to-treat survival advantage for liver cancer patients. However, liver grafts from live donors are almost always small for size for adult recipients. Besides, tumor recurrence and metastasis after living donor liver transplantation have been reported. METHOD: An orthotopic Buffalo rat liver transplantation model using whole (100%, group W) and small-for-size grafts (50%, group S) was applied. Hepatoma cells were injected into the grafts after reperfusion. Comparison was made as regards acute phase graft injury and tumor growth together with cell proliferation (Ki67), angiogenesis (vascular endothelial growth factor), stellate cell activation (alpha-smooth muscle actin), and cell signaling pathway related to migration and invasion (Rac, rho-associated, coiled-coil containing protein kinase, and proline-rich tyrosine kinase 2). Invasiveness of the tumors developed was further assessed after their direct implantation into livers of nude mice. RESULTS: Liver tumors developed earlier and faster in group S with significantly greater tumor burden [hepatic replacement area: 61%; range, 47%-72%; vs. 18%; 12%-27%; P = 0.001] and tumor cell proliferation (92% vs. 59%; P = 0.0021) in a more invasive growth pattern with a higher incidence of venous invasion (91.7% vs. 25%; P = 0.003) and more frequent hepatic stellate cell activation. There was upregulation of protein expression of Rac/rho-associated, coiled-coil containing protein kinase/proline-rich tyrosine kinase 2/vascular endothelial growth factor signaling in group S. When implanted into livers of nude mice, tumors from group S had a higher incidence of local (70% vs. 0%; P = 0.003) and lung metastasis (50% vs. 0%; P = 0.033). This phenotype was consistent with their ultrastructural features linking to angiogenesis and invasiveness. CONCLUSION: Significant activation of cell signaling pathways leading to tumor invasion and migration in small-for-size liver grafts promotes tumor growth and metastasis after liver transplantation.

Suppression of liver tumor growth and metastasis by adiponectin in nude mice through inhibition of tumor angiogenesis and downregulation of Rho kinase/IFN-inducible protein 10/matrix metalloproteinase 9 signaling.

PURPOSE: We aimed to investigate the effects of adiponectin on liver cancer growth and metastasis and explore the underlying mechanisms. EXPERIMENTAL DESIGN: An orthotopic liver tumor nude mice model with distant metastatic potential was applied. Either Ad-adiponectin (1 x 10(8); treatment group) or Ad-luciferase (control group) was injected via portal vein after tumor implantation. Tumor growth and metastasis were monitored by Xenogen In vivo Imaging System. Hepatic stellate cell activation by alpha-smooth muscle actin staining, microvessel density by CD34 staining, macrophage infiltration in tumor tissue, and cell signaling leading to invasion, migration [Rho kinase (ROCK), IFN-inducible protein 10 (IP10), and matrix metalloproteinase 9], and angiogenesis [vascular endothelial growth factor (VEGF) and angiopoietin 1] were also compared. Tumor-nontumor margin was examined under electron microscopy. Direct effects of adiponectin on liver cancer cells and endothelial cells were further investigated by a series of functional studies. RESULTS: Tumor growth was significantly inhibited by adiponectin treatment, accompanied by a lower incidence of lung metastasis. Hepatic stellate cell activation and macrophage infiltration in the liver tumors were suppressed by adiponectin treatment, along with decreased microvessel density. The treatment group had less Ki-67-positive tumor cells and downregulated protein expression of ROCK1, proline-rich tyrosine kinase 2, and VEGF. Tumor vascular endothelial cell damage was found in the treatment group under electron microscopy. In vitro functional study showed that adiponectin not only downregulated the ROCK/IP10/VEGF signaling pathway but also inhibited the formation of lamellipodia, which contribute to cell migration. CONCLUSION: Adiponectin treatment significantly inhibited liver tumor growth and metastasis by suppression of tumor angiogenesis and downregulation of the ROCK/IP10/matrix metalloproteinase 9 pathway.

Ischemia-reperfusion of small liver remnant promotes liver tumor growth and metastases--activation of cell invasion and migration pathways.

Elucidating the mechanism of liver tumor growth and metastasis after hepatic ischemia-reperfusion (I/R) injury of a small liver remnant will lay the foundation for the development of therapeutic strategies to target small liver remnant injury, and will reduce the likelihood of tumor recurrence after major hepatectomy or liver transplantation for liver cancer patients. In the current study, we aimed to investigate the effect of hepatic I/R injury of a small liver remnant on liver tumor development and metastases, and to explore the precise molecular mechanisms. A rat liver tumor model that underwent partial hepatic I/R injury with or without major hepatectomy was investigated. Liver tumor growth and metastases were compared among the groups with different surgical stress. An orthotopic liver tumor nude mice model was used to further confirm the invasiveness of the tumor cells from the above rat liver tumor model. Significant tumor growth and intrahepatic metastasis (5 of 6 vs. 0 of 6, P=0.015), and lung metastasis (5 of 6 vs. 0 of 6, P=0.015) were found in rats undergoing I/R and major hepatectomy compared with the control group, and was accompanied by upregulation of mRNA levels for Cdc42, ROCK (Rho kinase), and vascular endothelial growth factor, as well as activation of hepatic stellate cells. Most of the nude mice implanted with liver tumor from rats under I/R injury and major hepatectomy developed intrahepatic and lung metastases. In conclusion, hepatic I/R injury of a small liver remnant exacerbated liver tumor growth and metastasis by marked activation of cell adhesion, invasion, and angiogenesis pathways.

A crucial role for dendritic cell (DC) IL-10 in inhibiting successful DC-based immunotherapy: superior antitumor immunity against hepatocellular carcinoma evoked by DC devoid of IL-10.

The dendritic cell (DC)-based tumor immunotherapy has been a new promise of cure for cancer patients, but animal studies and clinical trials have thus far only shown limited success, especially in treating established tumors. Certain immunosuppressive mechanisms triggered by tumor cells or the derivatives are believed to be a major obstacle. We studied the role of DC-derived IL-10 and its negative impact on vaccine efficacy in mouse models. Liver tumor cells were injected via the portal vein, giving rise to disseminated intrahepatic tumors, or s.c. to form solid but extrahepatic tumors. Bone marrow-derived DCs were generated from normal or IL-10-deficient mice and used as the vector to deliver tumor Ags. We demonstrate here that DCs devoid of IL-10, a potent immunosuppressive cytokine, are superior over conventional DCs in triggering antitumor immunity. The IL-10(-/-)DCs were highly immunogenic, expressed enhanced levels of surface MHC class II molecules, and secreted increased amounts of Th1-related cytokines. By inducing tumor-specific killing and through the establishment of immunological memory, the vaccines delivered by IL-10(-/-)DCs could evoke strong therapeutic and protective immunity against hepatocellular carcinoma in the mouse models. These findings will have great clinical impact once being translated into the treatment of malignant, and potentially infectious, diseases in humans.