IGFBP7 Deletion Promotes Hepatocellular Carcinoma
Menée à l'aide de modèles murins, cette étude met en évidence des mécanismes de nature immunitaire par lesquels la protéine IGFBP7 exerce une fonction de suppresseurs de tumeurs dans les carcinomes hépatocellulaires
Activation of IGF signaling is a major oncogenic event in diverse cancers, including hepatocellular carcinoma (HCC). In this setting, the insulin-like growth factor binding protein IGFBP7 inhibits IGF signaling by binding the IGF-1 receptor (IGF-1R), functioning as a candidate tumor suppressor. IGFBP7 abrogates tumors by inhibiting angiogenesis and inducing cancer-specific senescence and apoptosis. Here we report that Igfbp7-deficient mice exhibit constitutively active IGF signaling, presenting with pro-inflammatory and immunosuppressive microenvironments and spontaneous liver and lung tumors occurring with increased incidence in carcinogen-treated subjects. Igfbp7 deletion increased proliferation and decreased senescence of hepatocytes and mouse embryonic fibroblasts, effects that were blocked by treatment with IGF-1 receptor inhibitor. Significant inhibition of genes regulating immune surveillance was observed in Igfbp7-/- murine livers, which was associated with a marked inhibition in antigen cross-presentation by Igfbp7-/- dendritic cells. Conversely, IGFBP7 overexpression inhibited growth of HCC cells in syngeneic immunocompetent mice. Depletion of CD4+ or CD8+ T lymphocytes abolished this growth inhibition, identifying it as an immune-mediated response. Our findings define an immune component of the pleiotropic mechanisms through which IGFBP7 suppresses HCC. Furthermore, they offer a genetically based preclinical proof of concept for IGFBP7 as a therapeutic target for immune management of HCC.