Bcl-2, bax and p53 expression in rectal adenocarcinoma. Correlation with classic pathologic prognostic factors and patients' outcome.
BACKGROUND
Bcl-2 oncoprotein inhibits apoptosis, whereas bax protein promotes apoptosis by enhancing cell susceptibility to apoptotic stimuli. This study examined the bcl-2, bax and p53 expression in rectal adenocarcinomas and their relationship with tumor prognosis.


METHODS
Paraffin-embedded 4-microm tumor sections obtained from patients with rectal adenocarcinoma who underwent colectomy for therapeutic reasons, were analyzed with a standard streptavidin biotin peroxidase method, using polyclonal and monoclonal antibodies. Patients were followed up for 1.5-83 (mean +/- SD: 47.19 +/- 6.2) months.


RESULTS
Positive immunoreactivity for bcl-2, bax and p53 was detected in 21 (37%), 28 (50%) and 45 (80%) tumors, respectively. Bax was co-expressed in 17 out of 21 bcl-2(+) cases, whereas p53 was co-expressed in 18 out of 21 bcl-2(+) and 17 out of 28 bax(+) cases. Loss of bax expression was associated with advanced stage and high grade tumors (p < 0.01). Local (n = 6) or distant (n = 5) tumor recurrence was established in 11 cases. All these cases were bax(+), bcl-2(-) and p53(+). Bax and p53 expressions were correlated with adverse outcome (p < 0.05) while bcl-2 presence did not influence survival. Bcl-2(-)/bax(+)/p53(+) cases showed lower survival than bax(+)/bcl-2(+)/p53(+) cases (p < 0.001).


CONCLUSIONS
In rectal adenocarcinoma, bax and bcl-2 proteins co-express frequently with p53. Co-expression of bax with p53 protein is associated with poor clinical outcome, especially in cases without concomitant expression of bcl-2.
Tsamandas
Athanassios C
AC
Department of Pathology, University of Patras School of Medicine, Patras, Greece.
Kardamakis
Dimitrios
D
Petsas
Theodore
T
Zolota
V
V
Vassiliou
V
V
Matatsoris
T
T
Kalofonos
Haralabos
H
Vagianos
Constantine E
CE
Scopa
Chrisoula D
CD
D000230:Adenocarcinoma / Q000175:diagnosis / Q000401:mortality / Q000473:pathology*; D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D012004:Rectal Neoplasms / Q000175:diagnosis / Q000401:mortality / Q000473:pathology*; D015996:Survival Rate; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein