Recent findings suggest that co‐expression of NOS2 and COX2 is a strong prognostic indicator in triple‐negative breast cancer patients. These two key inflammation‐associated enzymes are responsible for the biosynthesis of NO and PGE₂, respectively, and can exert their effect in both an autocrine and paracrine manner. Impairment of their physiological regulation leads to critical changes in both intra‐tumoural and intercellular communication with the immune system and their adaptation to the hypoxic tumour micro‐environment. Recent studies have also established a key role of NOS2–COX2 in causing metabolic shift. This review provides an extensive overview of the role of NO and PGE₂ in shaping communication between the tumour micro‐environment composed of tumour and immune cells that in turn favours tumour progression and metastasis.

This article is part of a themed section on Nitric Oxide 20 Years from the 1998 Nobel Prize. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.2/issuetoc