Alpha‐2c Adrenergic Receptor Promotes the Malignant Phenotype of Colon Cancer Cells

Abstract

Cancer remains one of the leading causes of death worldwide, with colorectal cancer (CRC) being the third most common type. Accumulating evidence shows that stress plays a pivotal role in the malignant phenotype of CRC, by promoting hallmarks of CRC including cellular proliferation, migration, invasion, and angiogenesis. During stressful situations, the sympathetic nervous system is activated, causing an elevation in levels of catecholamines, including epinephrine which elicits its effects mainly by activating adrenoceptors. Interestingly, however, the role of alpha2C adrenergic receptor (a2c‐AR) in CRC malignancy remains obscure. Here, we proposed that activation of a2c‐AR potentiates the malignant phenotype of human CRC cells. Treatment of human colon cancer cell lines, SW480 and HT‐29, with increasing concentrations of a2‐AR specific agonist (UK 14,304; 10, 30 or 100 nM) for different time points (24, 48, or 72 hours) did not cause a significant change in proliferation. However, using monolayer scratch assay, a significant increase in migration was observed after treatment with UK 14,304 (100 nM) for 8 and 12 hours in both cell lines. This was further supported by a transwell migration assay where UK 14,304 increased cell migration. Pretreatment with a specific a2c‐AR antagonist (JP 1302; 100 nM) abolished the UK 14,304‐induced cell migration. This increase in migratory capacity was concomitant with increased Rho activation evident by translocation of Rho from cytoplasm to the membrane as well as via a Rhotekin‐binding activation assay. Moreover, treatment with UK 14,304 evoked actin reorganization, an element known to be a prerequisite for cell migration. The induced Rho activation and actin cytoskeletal rearrangement could be mediated by increased oxidative stress since treatment with UK 14,304 increased ROS production. Importantly, ROS is known to induce migration of these cells. Furthermore, adhesion of colon cancer cells to TNF‐alpha‐activated HUVECs was promoted by UK 14,304. This UK14,304‐induced adhesion was followed by a dramatic increase in transendothelial migration of SW480 through HUVECs, clearly indicating that a2c‐AR activation may promote intra‐ or extravasation. Because breaking the endothelial cell barrier requires matrix digestion, we measured the levels of matrix metalloproteinases (MMPs). Importantly, stimulation of a2c‐ARs by UK14,304 increased the production of MMP2 and MMP9, and JP 1302 abolished this UK14,304‐induced production. Taken together, our data suggests that a2c‐AR potentiates the migratory and invasive capacities and hence the malignant phenotype of human colon cancer cells. Therefore, a2c‐AR may represent a novel target in the treatment of CRC.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.