Colon cancer and the immune system: The role of tumor invading T cells

Abstract

Colon cancer is still one of the leading causes of cancer death worldwide. Although the host immune system has been shown to react against tumor cells, mainly through tumor infiltrating lymphocytes and NK cells, tumor cells may utilize different ways to escape anti-tumor immune response. Tumor infiltration of CD8+ and CD4+ (T-bet+) effector T cells has been attributed to a beneficial outcome, and the enhancement of T cell activation through T cell receptor stimulation and co-stimulatory signals provides promising strategies for immunotherapy of colon cancer. Growing evidence supports a role for the Fas/FasL system in tumor immunology, although the mechanisms and consequences of FasL activation in colon cancer are not completely understood. In animal models, depletion of regulatory T cells (CD4+ CD25+ T cells) can enhance the anti-tumor immune response under certain conditions. Taken together, recent insights in the immune reaction against colon carcinoma have provided new approaches to immunotherapy, although much remains to be learned about the exact mechanisms.

Pretreatment Neutrophil/Lymphocyte Ratio as a Prognostic Aid in Colorectal Cancer

“…It is now becoming clear that the tumor microenvironment, which is largely orchestrated by inflammatory cells, is an essential participant in the neoplastic process, promoting proliferation, survival, and migration. For this reason many studies have been focused on the evidence of the role of inflammation in carcinogenesis recently (Waldner et al, 2006, Roxburgh et al, 2010Unal et al, 2013). Generally, studies described that lymphopenia means an impaired cell-mediated immunity, while neutrophilia is linked response to systemic inflammation (Zahorec et al, 2001).…”

Inflammatory bowel disease and intestinal cancer: a paradigm of the Yin–Yang interplay between inflammation and cancer

“…Colitis-associated cancer is characterized by a dense infiltrate of immune cells, including macrophages, dendritic cells and T cells, which include the subset of CD8 þ and CD4 þ (T-bet þ ) effector T cells and CD4 þ CD25 þ T cells (Waldner et al, 2006). However, the functional role of these immune cells is only recently beginning to be unveiled.…”

Tumor development in murine ulcerative colitis depends on MyD88 signaling of colonic F4/80+CD11bhighGr1low macrophages

“…The reasons for this increased cancer occurrence are not fully understood, but there is ample evidence from murine models that the presence of chronic inflammation provides an environment that favors the growth of neoplastic cells (9)(10)(11)(12)(13). Thus, in recent studies of a murine model of colitis, dextran sodium sulfate-induced colitis (DSS-colitis), it was shown that the inflammation is a necessary antecedent for the induction of colon tumors by a carcinogenic agent, azoxymethane (AOM) (13)(14)(15)(16)(17).…”