Dual role of inflammatory mediators in cancer.

Inflammation is the body's response to noxious stimuli such as infectious, physiological or chemical agents, it releases various inflammatory mediators via immune cells such as neutrophils, macrophages, and lymphocytes. These inflammatory mediators are growth factors, chemokines, and cytokines. Reactive oxygen species (ROS) and nitrogen species (RNS) activate transcriptional factors (NF-KB, STAT-3) and bring about cellular proliferation, genomic instability, angiogenesis, resistance to apoptosis, invasion, and metastasis. The presence of inflammatory mediators in the tumour microenvironment inhibits or promotes inflammation-induced cancer, depending on various stages of immune surveillance of the tumor i.e. by immunoediting, immunoprocessing, and immunoevasion. Myeloid derived suppressor cells are immature myeloid progenitor cells. They are the major immune-suppressor cells in the tumour inflammatory microenvironment that activate transcriptional factor NF-KB, STAT-3 to bring about tumour progression. Another gene which the micro RNA's are noncoding RNA molecules is found to have a link with inflammation and cancer. This article discusses the roles of inflammatory mediators involved in antitumour or protumour activity within the context of the tumour microenvironment.