The Impact of the Serotonin on the Cause and Treatment of Cancer

Somayeh Zaminpira,Sorush Niknamian

doi:10.15436/2377-0902.17.1629

Abstract

This review article goes through many researches based on the effectiveness of the neurotransmitter serotonin on cancer cells and also the impact of SSRIs (selective serotonin reuptake inhibitors) drugs on the cause of certain types of cancers. Serotonin has been shown to be a mutagenic factor for a wide range of normal and tumor cells. Serotonin exhibits a growth stimulatory effect in aggressive cancers and carcinoids usually through 5- HT1 and 5-HT2 receptors. In contrast, low doses of serotonin can inhibit tumor growth via the decrease of blood supply to the tumor, suggesting that the role of serotonin on tumor growth is concentration-dependent. Serum serotonin level was found to be suitable for prognosis evaluation of urothelial carcinoma in the urinary bladder, adenocarcinoma of the prostate and renal cell carcinoma.The mechanism that connect serotonin with tumor evolution seem to be related to the serotonin impact on tumor associated macrophages.

Highlights

Carcinoid Syndrome Carcinoid syndrome is a paraneoplastic syndrome comprising the signs and symptoms that occur secondary to carcinoid tumors
Other components of the carcinoid syndrome are diarrhea[5], a pellagra-like syndrome, fibrotic lesions of the endocardium, on the right side of the heart resulting in insufficiency of the tricuspid valve and, less frequently, the pulmonary valve and, uncommonly, bronchocon
Selective Serotonin Reuptake Inhibitors (SSRI) may lead to both tumor progression and tumor inhibition via two different mechanisms and it is a matter of luck and probably tumor type regarding which of the mechanism will dominate

Summary

Introduction

Carcinoid Syndrome Carcinoid syndrome is a paraneoplastic syndrome comprising the signs and symptoms that occur secondary to carcinoid tumors. The syndrome includes flushing and diarrhea, and less frequently, heart failure, emesis and broncho constriction[1]. It is caused by endogenous secretion of mainly serotonin and kallikrein. Carcinoid tumors produce the vasoactive substance, serotonin[4] It is commonly, but incorrectly, thought that serotonin is the cause of the flushing. The flushing results from secretion of kallikrein, the enzyme that catalyzes the conversion of kininogen to lysyl-bradykinin. The latter is further converted to bradykinin, one of the most powerful vasodilators known. Other components of the carcinoid syndrome are diarrhea (probably caused by the increased serotonin, which greatly increases peristalsis, leaving less time for fluid absorption)[5], a pellagra-like syndrome (probably caused by diversion of large amounts of tryptophan from synthesis of the vitamin B3niacin, which is needed for NAD production, to the synthesis of serotonin and other 5-hydroxyindoles), fibrotic lesions of the endocardium, on the right side of the heart resulting in insufficiency of the tricuspid valve and, less frequently, the pulmonary valve and, uncommonly, bronchocon-

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