The capacity of the immune system to distinguish foreign from self-antigen, and to subsequently eliminate the threat of disease
without injuring the host is crucial for survival. It also serves to defend against tumor formation and progression via a process termed
cancer immunosurveillance. Innate and adaptive immune cell types and effector molecules collectively function as extrinsic tumorsuppressor
mechanisms. However, tumors may escape immunesurveillance through a variety of mechanisms that create a local microenvironment
that is unfavorable for effective tumor immunity. Transforming growth factor β (TGF-β) has pleiotropic effects on the immune
system, and is recognized as one of the most potent immunosuppressive agents in facilitating oncogenesis. The TGF-β pathway promotes
cancer progression by concomitantly enhancing tumor metastases while inhibiting the protective host immunity. In this review, we discuss
mechanisms through which TGF-β interferes with the development of an anti-tumor immunity and potential means through which to
circumvent its activity in order to define more effective cancer immunotherapies.
Keywords: TGF-β, natural killer, dendritic cells, CD8+ T cells, Th1, Th2, Th17, treg cells, cancer, anti-tumor immunity.
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