Label-Free Dynamic Mass Redistribution Reveals Low-Density, Prosurvival α1B-Adrenergic Receptors in Human SW480 Colon Carcinoma Cells

Small molecules that target the adrenergic family of G protein–coupled receptors (GPCRs) show promising therapeutic efficacy for the treatment of various cancers. In this study, we report that human colon cancer cell line SW480 expresses low-density functional α 1B -adrenergic receptors (ARs) as revealed by label-free dynamic mass redistribution (DMR) signaling technology and confirmed by quantitative reverse-transcriptase polymerase chain reaction analysis. Remarkably, although endogenous α 1B -ARs are not detectable via either [ 3 H]-prazosin–binding analysis or phosphoinositol hydrolysis assays, their activation leads to robust DMR and enhanced cell viability. We provide pharmacological evidence that stimulation of α 1B -ARs enhances SW480 cell viability without affecting proliferation, whereas stimulating β -ARs diminishes both viability and proliferation of SW480 cells. Our study illustrates the power of label-free DMR technology for identifying and characterizing low-density GPCRs in cells and suggests that drugs targeting both α 1B - and β -ARs may represent valuable small-molecule therapeutics for the treatment of colon cancer.