Neuro-neoplastic interrelationships in colorectal level - immunohistochemical aspect in three cases and review of the literature.

Colorectal cancer represents a severe public health issue. Recent studies have shown the essential role played by nerves and their neurotransmitters in tumor initiation and progression. The aim of this study is to asses the expression of beta 2-adrenergic receptors (β2A) for adrenaline and noradrenaline, and the expression of M3 muscarinic receptors (M3R) for acetylcholine (neurotransmitters produced and released by sympathetic and parasympathetic afferents of the digestive tract and also by the enteric nervous system) in different tumor gradings of colorectal adenocarcinoma, and also the tropomyosin receptor kinase A (TrkA) for the nerve growth factor produced by the cells of colorectal adenocarcinoma. Beta 2-adrenergic receptors were expressed both in normal colic tissue and in the tumor tissues, from the three patients included in the study. It was observed that both area and integrated optical density (IOD) are more elevated for this type of receptor in tumor tissues than in normal colic tissue. For the M3 muscarinic receptors, similarly to beta 2-adrenergic receptors, it was observed a growth both of the area and of the IOD with the tumor grading. The presence of TrkA receptors was also observed both in the normal colic mucosa and in the tumor tissues examined, but with a significant reduction of the signal in the poorly differentiated tumor tissue. Understanding the neurobiology of cancer in this context becomes necessary for establishing much more complex and targeted molecular targeted therapies.