Evidence forreciprocity ofbcl-2 andp53expression inhumancolorectal adenomas andcarcinomas

in47samples ofhistologically normal colonic mucosa,19adenomas and53adenocarcinomas. Expression ofbcl-2 incolonic crypts > 5cm fromthe tumourswas confined tocryptbasesbutwas more extensive andintense innormalcrypts < 5 mm from cancers.A higher proportion ofadenomas(63.2%) thancarcinomas (36.5%) expressed bcl-2 (P<0.05). A lower proportion ofadenomas (31.6%) thancarcinomas (62.3%) expressed p53(P<0.02). A total of26.3%of adenomasand22% ofcarcinomas expressed bothbcl-2 andp53.To determine whether thesesamples contained cells whichexpressed bothproteins, a dualstaining technique forbcl-2 andp53was used.Only1/19 adenomas and2/53carcinomas contained cells immunopositive forbothbcl-2 andp53.Moreover there was evidence ofreciprocity ofexpression ofbcl-2 andp53inthese three double staining neoplasms. We suggest that bcl-2provides a survival advantage intheproliferative compartment ofnormalcrypts andcolorectal neoplasms. However, itsexpression islostduring theevolution fromadenomatocarcinoma, whereasp53 expression isincreased, an eventgenerally coincident withtheexpression ofstabilised p53,whichwe presume torepresent themutantform.