Estrogen-receptor status determines differential regulation of α1- and α2-adrenoceptor-mediated cell survival, angiogenesis, and intracellular signaling responses in breast cancer cell lines

Abstract

Psychosocial stress promotes cancer pathogenesis involving angiogenesis through alterations in neuroendocrine-immune functions that may involve adrenoceptor (AR)-dependent signaling mechanisms in the brain, lymphoid organs, and cancerous cells. Various concentrations of α₁- and α₂- AR-specific agonists and antagonists were incubated in vitro with estrogen receptor-positive (ER +) MCF-7, and ER (-) MDA MB-231 cells to examine the secretions of VEGF-A, VEGF-C, and nitric oxide (NO), and expression of signaling molecules- p-ERK, p-CREB, and p-Akt on the proliferation of breast cancer cell lines. Cellular proliferation, VEGF-A and NO secretion, expression of p-ERK, p-CREB, and p-Akt were enhanced in MCF-7 cells treated with α₁-AR agonist while VEGF-C secretion alone was enhanced in MDA MB-231 cells. Treatment of MCF-7 and MDA MB-231 cells with α₂- AR agonist similarly enhanced proliferation and decreased NO production and p-CREB expression while VEGF-C secretion was decreased in MCF-7 cells and p-Akt expression was decreased in MDA MB-231 cells. α₁-AR inhibition reversed cellular proliferation and VEGF-A secretion by MCF-7 cells while α₂-AR inhibition reversed the proliferation of MCF-7 and MDA MB-231 cells and VEGF-C secretion by MCF-7 cells. Taken together, breast cancer pathogenesis may be influenced by distinct α-AR-mediated signaling mechanisms on angiogenesis and lymphangiogenesis that are dependent on estrogen receptor status.

Keywords: Clonidine; Idazoxan; Phenylephrine; Prazosin; Signaling molecules.