Coexpression of Bcl-2, c-Myc, and p53 oncoproteins as prognostic discriminants in patients with colorectal carcinoma

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Abstract
PURPOSE: This study was undertaken to evaluate the clinical use of Bcl-2, c-Myc, and p53 oncoproteins, either singly or in combination, as prognostic discriminants relative to recurrence and overall survival in patients with Dukes B or C colorectal carcinoma. METHODS: Analyses were made on archival pathology tissues of 48 patients with colorectal cancer. The oncoproteins were localized using commercially available monoclonal antibodies: clone 124 for Bcl-2, 9E11 for c-Myc, and DO-7 for p53. The avidin-biotin peroxidase complex method was used. Patients were followed up for a period of 2 to 36 months. RESULTS: Expression of Bcl-2 and c-Myc was cytoplasmic, whereas nuclear p53 immunoreactivity was localized in the tumor cells. Sixty percent (29/48), 65 percent (31/48), and 37 percent (18/ 48) of the tumors showed overexpression of Bcl-2, c-Myc, and p53 oncoproteins, respectively. Fifty-four percent (18/ 33) and 100 percent (9/9) of moderately and poorly differentiated tumors, respectively, were positive for Bcl-2 (P<0.01). No such correlation was noted for c-Myc and p53 oncoproteins. Univariate analysis showed that patients with Bcl-2 and c-Myc overexpression were associated with poorer overall survival than patients with Bcl-2-negative (P<0.0124) and c-Myc-negative (P<0.036) tumors. In addition, when patients were subgrouped according to Dukes stage, a statistically significant poorer overall survival was observed in Dukes C patients with Bcl-2-positive tumors (P<0.017). Furthermore, multivariate analysis revealed that coexpression of three oncoproteins was predictive of a worse prognosis than for those individuals expressing none of the oncoproteins (P<0.031) and only one positive oncoprotein (P<0.014). CONCLUSION: These findings suggest that oncoprotein coexpression possesses significant prognostic and potential therapeutic value; incorporation of molecular markers into future prospective randomized trials is advisable.