The Influence of Tumor Microenvironment on Tumor Progression; and Anticancer Therapies

: All tumors are surrounded by complex environmental components including blood and lymph vessels; cellular components like fibroblasts, endothelial cells, immune cells; and non-cellular stromal cytokines, extracellular vesicles, and extracellular matrix. All of these along with the tumor cells constitute the tumor microenvironment (TME). Also the physical and chemical factors within this tumor microenvironment including extracellular pH, hypoxia, elevated interstitial fluid pressure, and fibrosis closely associate with the tumor progression at local site, its metastasis to remote areas of the body, immunosuppression, and drug resistance exhibited by the tumor. These cellular and extracellular components of TME primarily contribute to the process of carcinogenesis. This review focuses on multiple factors that alter the microenvironment to make it favorable for tumor growth at primary site and its metastasis to secondary sites. Also some of the natural products that may help to treat the tumor conditions via alteration of this microenvironment are mentioned which may provide new venues for development of newer drugs halting the progression of the tumors.