ABSTRACT
Serotonin [5HT] has been shown to be a mitogenic factor in several carcinomas. Its mitogenic effect is elicited through a wide range of 5HT receptor subtypes. In this study, the effects of 5HT, 5HT[3] [1-phenylbiguanide hydrochloride] and 5HT[4] [cisapride] agonists in promoting the growth of the HT29 cell line and the growth-inhibition effect of the 5HT[3] receptor antagonist [Y-25130 hydrochloride] and 5HT4 receptor antagonist [RS 23597-190] were investigated. The expressions of 5HT[3] and 5HT[4] receptors in human colon cancer tissues and the HT29 cell line were studied. The growth-promoting and growth-inhibition effects of 5-HT, 5HT[3] and 5HT[4] agonists and antagonists on the HT29 cell line were studied using MTT assay. Receptor expression has been demonstrated by western blotting. The results showed that 5HT, 5HT[3], and 5HT[4] agonists caused significant proliferation of HT29 cells. 5HT[3] and 5HT[4] receptor antagonists had an inhibitory effect on the growth of these cells. Western blot analysis gave bands from colon tissue extracts and the HT29 cell line. The results indicate which 5HT[3] and 5HT[4] receptors are significantly expressed in both colon cancer tissue and the HT29 cell line. Expression for the 5HT[3] receptor is more potent. Furthermore, 5HT plays a mitogenic role in colon cancer cells and antagonists of 5HT[3], and 5HT[4] receptors can inhibit cancer cell growth