DOWN-REGULATION OF BCL-2 BY P53 IN NASOPHARYNGEAL CARCINOMA AND LACK OF DETECTION OF ITS SPECIFIC T(14-18) CHROMOSOMAL TRANSLOCATION IN FIXED TISSUES

High levels of bcl-2 protein have been found in a wide variety of huma n cancers. Since p53 gene inactivation occurs in over half of human ca ncers, it is possible that loss of p53-mediated repression of bcl-2 ge ne expression accounts, at least in part, for the frequent abnormaliti es in bcl-2 protein production seen in tumours. By using immunohistoch emical methods, we have analysed thirty-three nasopharyngeal carcinoma s for p53 and bcl-2 expression. We found an inverse correlation betwee n the expression of these two proteins (P < 0.001). Moreover, tire uti lized universal oligonucelotide primers of a region 5' to the bcl-2 MB R and at the 3' end of J(H) segments to initiate a DNA polymerase chai n reaction that amplified these bcl-2-J(H) junctures. Of the twelve na sopharyngeal carcinomas expressing bcl-2, none showed a t(14;18) chrom osome translocation. These findings may indicate potential mechanisms by which bcl-2 regulates apoptosis.