Assay for caspase activity
To further understand the details in 2-MCA-induced
apoptosis, the changes in activities of crucial caspases
involved in apoptosis were analyzed. The test is based
on the measure of the chromophore 7-amino-4-trifluoromethyl coumarin (AFC) after cleavage from the labeled
substrate DEVD- and LEHD-AFC by caspase-3 and -9,
respectively. The released AFC gives off a yellowgreen
fluorescence. COLO 205 cells were incubated with different concentrations of 2-MCA for 48 h and caspase-3
and -9 activities were determined using Fluorometric
Assay Kit from BioVision (Milpitas, CA, USA) following
the manufacturer’s instructions. The AFC light emission
was evaluated using the Tecan infinite M200 spectrophotometer (Tecan, Ma ¨nnedorf, Switzerland). Results are
expressed as the percentage of change in activity compared
to the untreated control.