Cancer immunotherapy: Targeting immunosuppressive tumor microenvironment

Abstract

Tumor microenvironment is an evolving source for targeting drug advancement for cancer. The tumor atmosphere is created and regulated by tumor and governed by tumor induced interactions and its association in cancer initiation, progression and metastasis. Vigorous growth of tumor requires an existence of a local vascular grid, with this dynamic growth of tumor, an environment is created where different factors influences in immune editing and immune surveillance and inflammation also play a vivacious role. Tumor progression requires a housing interaction and reciprocal feedback between extracellular matrix (ECM), host cells and cancer cells. This microenvironment consists of blood cells, fibroblast, immune cells, ECM and other cells. The dynamic combination of different cells and alternative factors induces the survival of tumor. Cellular variant generation are highly equivocal, genetically instable and highly unordered. Recent studies have helped to improve our understanding of the complex tumor microenvironment and its pathways associated with signaling, inflammation and other allied factors in various cancer. Tumor blood vessels, ECM significantly help in disease progression and on the other hand different infiltrating immune cells, cancer associated fibroblasts and angiogenic endothelial cells help tumor in nourishing that promote cell proliferation, dodge growth suppressors, activate invasion and motivate metastasis and reprogram energy metabolism. Host cells of the tumor microenvironment comprise of inflammatory cells including myeloid cells, tumor-associated neutrophils and tumor-associated macrophages. When activated they release mixture of growth factors, proteolytic enzymes, inflammatory mediators and cytokines. These factors are proxies in tumor progression. While tumor environment remains a potential candidate for drug development, it is important to decode the immunosuppressive cells and understand the molecular mechanism of each pathway underlying to strengthen the efficacy of cancer therapeutics.