Sildenafil Induces Cell Cycle Arrest and Apoptosis in Human Colorectal Cancer HT-29 Cells

Phosphodiesterase is an enzyme that degrades the phosphodiester bond in the second messenger molecules cAMP and cGMP, and regulates the localization, duration, and amplitude of cyclic nucleotide signaling within subcellular domains. Sildenafil is a potent and selective inhibitor of the type 5 cGMP-specific phosphodiesterase used clinically to treat erectile dysfunction and pulmonary arterial hypertension. In this study, we examined the effect of sildenafil on human colorectal cancer HT-29 cells. Our data showed that sildenafil induced cell cycle arrest and apoptosis, and cotreatment with a ROS scavenger N-acetyl-L-cysteine partially reversed cell apoptosis caused by sildenafil in human colorectal cancer HT-29 cells. Overall, our study suggests that sildenafil appears to be a promising new treatment option for colorectal cancer.