Bcl-2 expression in colorectal tumours. Correlation with p53, mdm-2, Rb proteins and proliferation indices.
Immunostaining for bcl-2 protein was performed in 27 colorectal adenomas and 108 colorectal adenocarcinomas. The aim of the study was to determine bcl-2 expression in correlation with p53, mdm-2 and Rb expression, with proliferation indices (Ki-67-LI, PCNA-LI) as well as with conventional clinicopathological variables. A higher proportion of adenomas (30.8%) than carcinomas (16.7%) expressed bcl-2 and conversely, a lower proportion of adenomas (7.4%) than carcinomas expressed p53 (57.1%), the difference being statistically significant (p<0.0001). No correlation of bcl-2 expression with p53 expression (parallel or inverse) as well as with the other parameters studied was observed in any tumour. The bcl-2+/p53- subgroup of cancers showed a trend for correlation with negative lymph node status. Our data suggest, that bcl-2 expression may be involved in the early phase of colorectal carcinogenesis regardless of p53 status, while p53 function may be involved in a late stage of the adenoma-carcinoma sequence. P53 is apparently not involved in the regulation of apoptosis in the colorectal neoplasias or perhaps bcl-2 expression, as an early event in colorectal tumours, may occur before changes of p53 take place. Tumours with bcl-2+/p53- immunophenotype are frequently associated with negative lymph node status and seem to have a less aggressive behavior.
Goussia
A C
AC
Department of Pathology, University of Ioaninna, Medical School, Greece.
Ioachim
E
E
Agnantis
N J
NJ
Mahera
M
M
Tsianos
E V
EV
D000230:Adenocarcinoma / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D000236:Adenoma / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D002455:Cell Division; D015179:Colorectal Neoplasms / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000096:biosynthesis*; D008297:Male; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D051736:Proto-Oncogene Proteins c-mdm2; D016160:Retinoblastoma Protein / Q000096:biosynthesis*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2