Expression of caspases-3,-6 and-8 and their relation to apoptosis in non-small cell lung carcinoma

We analyzed a set of 103 non-small cell lung carcinomas (NSCLCs) for caspas e-3, -6 and -8 expression and apoptosis, Additionally, the expression of bc l-2, bax and p53 were studied. Caspase-3 positivity appeared as diffuse, cy toplasmic staining and was restricted to the tumor area. In contrast, the i mmunoreactivity for caspase-6 was intense, granular and mostly located in s ingle cells or groups of tumor cells showing apoptotic morphology. The casp ase-8 expression pattern was a combination of the two other caspases studie d, featuring both diffuse and single-cell patterns restricted to the tumor area. No significant differences were seen in caspase -3, -6 and -8 express ion between tumors of different histological types or grades. The number of apoptotic cells and bodies was significantly higher in NSCLCs, in which ca spase-8 immunostaining was mainly seen in single cells (p = 0.017), whereas caspase -3 and -6 expression had no association with apoptosis. It is appa rent that, in lung tissue, up-regulation of caspase expression is a phenome non associated solely with neoplasia and reflects the readiness of the tumo r cells to undergo apoptosis. Interestingly, caspases -3, -6 and -8 each ha ve an individual staining pattern in NSCLC, perhaps reflecting their differ ent position in the caspase hierarchy. (C) 2001 Wiley-Liss, Inc.