Expression of caspase-3 and -7 does not correlate with the extent of apoptosis in primary breast carcinomas

Association between the rate of apoptosis and expression of the several relevant molecules (Bcl-2, pro- and active caspase-3, and caspase-7) was studied in 61 primary breast carcinomas. The rate of apoptosis detected both morphologically and by the TUNEL assay appeared to be high in 18 (30%), moderate in 14 (23%), and low in 29 (48%) carcinomas. High apoptotic index was strongly associated with advanced tumor grade and estrogen receptor positive (ER+) status but not with other investigated clinical or morphological parameters. Among the molecules studied, only the Bcl-2 protein expression demonstrated strong (inverse) correlation with the apoptotic index (p = 0.032). The data of this expected correlation was served as internal control in the study. Interestingly, high levels of the anti-apoptotic protein Bcl-2 was frequently co-incident with increased expression of pro-apoptotic molecules, such as active caspase-3 (p = 0.004) and caspase-7 (p = 0.001). However, expression of caspase-3 or caspase-7 did not show correlation with the extent of apoptosis or any clinico-morphological features, except overrepresentation of ER+ status in tumors expressing caspase-3 (p = 0.009). Thus, these findings indicate a general dysregulation of spontaneous apoptosis in primary breast tumors.