An immunohistochemical study of the simultaneous expression of bcl-2 and p53 oncoproteins in epithelial tumors of the colon and rectum.
OBJECTIVE
Bcl-2 and p53 genes may participate in a common pathway for regulation of apoptosis. The aims of this study were (1) to study the immunohistochemical expression of the bcl-2 oncoprotein in colorectal tumors, (2) to correlate it with that of p53 protein overexpression, and (3) to compare it with histopathologic prognostic factors, such as TNM classification and grade.


METHODS
Prospective study of expression of bcl-2 and p53 oncogenes in colorectal tumors. We examined 6 colorectal hyperplastic polyps, 33 adenomas, and 61 carcinomas.


METHODS
Regional academic medical center.


METHODS
An immunohistochemical study with bcl-2 and p53 antibodies was performed on frozen sections of colorectal tumors. The levels of bcl-2 and p53 expression were evaluated using a semiquantitative grading system. Two-color immunohistochemistry was performed to examine the intracellular colocalization of bcl-2 and p53 in all tumors with a strong positivity for both antigens.


RESULTS
Bcl-2 was expressed in 28 (85%) of the 33 adenomas, whereas p53 was expressed in only one adenoma, which had areas of in situ carcinoma. Bcl-2 and p53 were each expressed in 43 (70.4%) of the 61 carcinomas. Thirty-one (50%) of the colorectal carcinomas coexpressed the two oncoproteins. There was no correlation between the number of cells expressing bcl-2 and the number expressing p53 in a given carcinoma. No correlation was observed between the expression of bcl-2 or p53 and the established prognostic factor.


CONCLUSIONS
Abnormal bcl-2 oncoprotein expression appears earlier than p53 accumulation in colorectal carcinogenesis. This study suggests that there is more than one sequence and mechanism of bcl-2 and p53 gene deregulation in colorectal carcinomas.
Mosnier
J F
JF
Service d'Anatomie Pathologique, Hopital de Bellevue, Saint-Etienne, France.
Perret
A G
AG
Vindimian
M
M
Dumollard
J M
JM
Balique
J G
JG
Perpoint
B
B
Boucheron
S
S
D000230:Adenocarcinoma / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D000236:Adenoma / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003106:Colon / Q000737:chemistry / Q000378:metabolism / Q000473:pathology; D015179:Colorectal Neoplasms / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011127:Polyps / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53