APOPTOSIS AND EXPRESSION OF THE PROTOONCOGENES BCL-2 AND P53 AND THE PROLIFERATION FACTOR KI-67 IN HUMAN MEDULLARY-THYROID CARCINOMA

Apoptosis and immunoreactivity for bcl-2, p53, and Ki-67 were studied in 21 patients with medullary thyroid carcinoma (MTC). The DNA nick en d labeling method was used to assess apoptosis. The relationships betw een the different factors were analyzed, as were their relations to cl inicopathological data, including survival. More than 80% of the tumor s harbored apoptotic cells. Tumors in individuals who had died of the MTC disease had a higher percentage of apoptosis. All cases demonstrat ed immunoreactivity to bcl-2; disease-free individuals had a higher ra te than those with recurrent disease. No obvious pattern could be disc erned in the relation of p53 or Ki-67 to the outcome of the MTC diseas e. An inverse correlation between bcl-2 and apoptosis (r = -0.81; p < 0.01) was demonstrated. bcl-2 was significantly (p = 0.014) associated with apoptosis even after taking both p53 and Ki-67 into consideratio n, but these two factors were unrelated to apoptosis. None of the fact ors studied were correlated to crude survival, either in univariate or in multivariate analyses. This study established that bcl-2 immunorea ctivity is closely associated with apoptosis in MIG, suggesting that a downregulation of the bcl-2 protein is related to a more aggressive g rowth rate and might be a useful marker for the evaluation of MTC.