Interplay Between Oncoproteins and Antioxidant Enzymes in Esophageal Carcinoma Treated Without and With Chemoradiotherapy: A Prospective Study

Purpose To analyze p53, bcl-2, c-myc, and cyclooxygenase-2 protein expression changes and examine their relationship with various antioxidant enzymes in esophageal carcinoma patients. Methods and Materials Patients in Group 1 underwent transhiatal esophagectomy and those in Group 2 were administered chemoradiotherapy followed by surgery after 4 weeks of neoadjuvant therapy. Results The relationship analysis among the various protein markers and antioxidant enzymes showed an inverse correlation between bcl-2 and superoxide dismutase/catalase in tumor tissues, irrespective of the treatment arm followed. An important positive association was observed between bcl-2 and reduced glutathione levels in the tumor tissue of patients receiving neoadjuvant therapy. Another apoptosis-modulating marker, c-myc, in the tumor tissue of Group 2 patients showed similar pattern levels (high and low) as that of superoxide dismutase/catalase. The association of cyclooxygenase-2 and p53 with various antioxidant enzymes showed a significant positive correlation between cyclooxygenase-2 expression and catalase activity and an inverse trend between p53 expression and superoxide dismutase and catalase activity in the tumor tissue of patients given neoadjuvant therapy. In addition, patients with overexpressed p53 protein levels had lower glutathione peroxidase enzyme levels and vice versa in the tumor tissue of patients who had undergone surgery as their main mode of treatment. Conclusion The results of this study broaden the insight into the relationships shared among oncoproteins and the antioxidant defense system, and this could be helpful in the clinical management of esophageal carcinoma.