Expression and significance of autonomic nerves and α9 nicotinic acetylcholine receptor in colorectal cancer

The present study evaluated the distribution of sympathetic and parasympathetic nerves and the expression of the α9 nicotinic acetylcholine receptor (α9nAChR) and investigated their potential association with colorectal cancer (CRC) development. The distribution of autonomic nerves and α9nAChR in CRC was detected by immunohistochemistry, which was then used to analyze their association with clinicopathological parameters and prognosis. Sympathetic fibers were primarily observed in the stroma adjacent to cancer cells, whereas parasympathetic fibers were primarily observed in the stroma away from cancer cells. Patients with samples positive for sympathetic nerve fibers had less lymph node invasion and a better prognosis compared with patients with samples negative for sympathetic nerve fibers. The expression of parasympathetic nerves in patients >60 years old was increased compared with patients ≤60 years old. The expression of parasympathetic nerves in patients with lymph node invasion was increased compared with patients without lymph node invasion. The detection of parasympathetic nerves gradually increased as CRC (T stage) advanced. Patients with parasympathetic negative samples had better prognoses compared with patients with parasympathetic positive samples. The expression of α9nAChR was principally localized in cellular membranes and the cytoplasm of CRC tissues and it was revealed to have a positive association with the number of parasympathetic nerves. Increased α9nAChR expression was observed in patients >60 years old compared with patients <60 years old. The detection rate of α9nAChR in tissues from patients with lymph node invasion was increased compared with patients without lymph node invasion. The detection of α9nAChR gradually increased as the CRC stage advanced. The prognoses for patients with α9nAChR negative tissue were improved compared with the prognoses for patients with α9nAChR positive tissue. Sympathetic nerves were primarily detected in the early phases of CRC and indicated a good prognosis. Parasympathetic nerves and α9nAChR were principally observed in the late phases of cancer and indicated a poor prognosis. The present study revealed that parasympathetic nerves may promote the progression of CRC through α9nAChR.