Selective ß2-AR Blockage Suppresses Colorectal Cancer Growth Through Regulation of EGFR-Akt/ERK1/2 Signaling, G1-Phase Arrest, and Apoptosis.

ABSTRACT

The stress-upregulated catecholamines-activated ß1- and ß2-adrenergic receptors (ß1/2-ARs) have been shown to accelerate the progression of cancers such as colorectal cancer (CRC). We investigated the underlying mechanism of the inhibition of ß1/2-ARs signaling for the treatment of CRC and elucidated the significance of ß2-AR expression in CRC in vitro and in clinical samples. The impacts of ß1/2-AR antagonists in CRC in vitro and CRC-xenograft in vivo were examined. We found that repression of ß2-AR but not ß1-AR signaling selectively suppressed cell viability, induced G1-phase cell cycle arrest, caused both intrinsic and extrinsic pathways-mediated apoptosis of specific CRC cells and inhibited CRC-xenograft growth in vivo. Moreover, the expression of ß2-AR was not consistent with the progression of CRC in vitro or in clinical samples. Our data evidence that the expression profiles, signaling, and blockage of ß2-AR have a unique pattern in CRC comparing to other cancers. ß2-AR antagonism selectively suppresses the growth of CRC accompanying active ß2-AR signaling, which potentially carries wild-type KRAS, in vitro and in vivo via the inhibition of ß2-AR transactivated EFGR-Akt/ERK1/2 signaling pathway. Thus, ß2-AR blockage might be a potential therapeutic strategy for combating the progressions of ß2-AR-dependent CRC.