The effect of hyperthermia and verapamil on primary and metastatic colon adenocarcinoma cell-lines - inhibition of proliferation, cell-cycle distribution and onset of apoptosis

Administration of the combination of hyperthermia and verapamil significantly decreased proliferation of HT-29 and SW-620 cells while hyperthermia or verapamil alone did not cause such growth inhibition. DNA histograms showed no significant changes in the cell cycle distribution of either cell line after hyperthermia treatment. After the administration of verapamil, a significant increase in both cell lines of the G(2)-M fraction was seen at 6, 20, and 30 hours in comparison to control with a concomitant decrease in G(1) phase population. The combination of hyperthermia and verapamil resulted in an accumulation of cells in G(2)-M phase with subsequent release from the arrest and appearence the cells showing fragmentation of chromatin into nucleosomal oligomers, the hallmark of programmed cell death (apoptosis).