β-blockers having specific affinities to β-adrenergic receptors are routinely used to treat cardiovascular problems. Additionally, it has been demonstrated that these drugs can be effective in treating apoptosis-related diseases. The current study was conducted to investigate the cytotoxic and apoptotic effects of β-1 selective esmolol, β-2 selective ICI-118,551, and non-selective nadolol blockers on the cancerous and healthy lung cells. MTT test was used to evaluate cytotoxicity. Apoptotic actions were examined by using Annexin V-FITC/PI assay, JC-1 staining, ROS test, and the determination of the caspase-4 and -9, Bcl-2, Bax, Bax/Bcl-2, and JNK levels. Although the MRC-5 showed greater resistance than A549 cells, the β-blockers at 150-250 µM exhibited different levels of cytotoxic effect on both lung cell lines. Esmolol was found to be the most ineffective blocker and the increases in Bcl-2 protein levels were appeared to be effective in resistance to this drug. The increases in reactive oxygen species (ROS) together with the increase in caspase-4 and Bax protein levels have been shown to play a role in ICI-118,551 induced lung cell death. Nadolol was the most effective blocker increasing the total apoptotic cell population in both lung cells, which was based on both mitochondrial and endoplasmic reticulum stress. When the selectivities of the β-blockers are considered, it seems that β-2 specific antagonism predominantly mediated the death of lung cells, and the overwhelming factors causing apoptosis mainly varied depending on the selectivity of the blockers.
Keywords: Apoptosis; Cytotoxicity; Esmolol; ICI-118,551; Lung cells; Nadolol.