Tumor Microenvironment—A Short Review of Cellular and Interaction Diversity

SIMPLE SUMMARY: Scientists around the world have long been interested in understanding the biology of cancer. Numerous studies that have been carried out so far clearly show that the development of cancer stems not only from a genetic mutation, but also from a network of interconnections between chemical molecules and cells of various body systems. The complexity of the processes taking place in the tumor environment makes it extremely difficult to select a targeted treatment in patients with various types of cancer. Numerous scientific reports have revealed some of the interactions and processes responsible for tumor progression. In the era of molecularly targeted therapies and immunotherapy, this knowledge plays a key role in overcoming the mechanisms of cancer escape from immune system surveillance and in developing appropriate anti-cancer treatment. ABSTRACT: The tumor microenvironment is a complex network of various interactions between immune cells and non-cellular components such as the extracellular matrix, exosomes and interleukins. Moreover, tumor heterogeneity and its constant modification may alter the immunophenotype and become responsible for its resistance regarding the therapies applied However, it should be remembered that in a strongly immunosuppressive neoplastic microenvironment, the immune system cells undergo reprogramming and most often cease to fulfill their original function. Therefore, understanding what happens within the tumor microenvironment, and which mechanisms are responsible for tumor development and progression should let us know how cancer could protect itself against the immune system. The presented review summarizes the latest information on the interactions between the tumor microenvironment and the cellular and non-cellular components, as well as their impact on cancer development, progression and immune system exhaustion.