Cellular Oncology 27 (2005) 245-253 245 IOS Press p53, Bcl-2 and C-Myc expressions in colorectal carcinoma associated with schistosomiasis in Egypt

Abstract. Background and aims: Oncogenes and tumor suppressor genes expression are well described in bladder cancer associated with schistosomiasis especially in Egypt. Scarce studies were directed to colorectal cancer (CRC) associated with Schistosoma mansoni (S. mansoni). Apoptosis (programmed cell death) and the genes regulating this process (e.g., Bcl-2) have recently become a focus of interest in the study of cancer development and progression. In the present study, we aimed to investigate the expression pattern of p53, Bcl-2 and C-Myc in CRC tissues obtained from Egyptian colorectal cancer patients divided in two different groups, one associated with Schistosoma mansoni (CRC-Sm) and the other without Schistosoma mansoni (CRC-NSm). Methods: Seventy-five CRC tumors containing 36 draining lymph node metastatic tumors were immunohistochemically stained using specific monoclonal antibodies for p53, Bcl-2 and C-Myc, in addition the apoptotic activity of these tumors were analyzed. Results and conclusions: Regardless of the S. mansoni infection, the obtained results showed that the apoptotic activity was more evident in p53 diffuse positive tumors (P = 0.021). There was a significant correlation between p53 diffuse positive staining and Bcl-2 positive immunostaining (P = 0.011). Signet ring cell carcinoma and mucinous adenocarcinoma exhibited both intense C-Myc expression than non-mucinous carcinoma (P = 0.001). When adjusting for S. mansoni infection, 58.3% of CRC-Sm cases were Bcl-2 positive compared to only (33.3%) of CRC-NSm (P = 0.046). Apoptotic activity was more evident in the latter group than of CRC-Sm tumors (P = 0.009). p53 and C-Myc expressions were found insignificantly different in CRC-Sm compared with CRC-NSm (P > 0.05). These observations suggest that the genotoxic agents produced endogenously through the course of schistosomiasis mansoni may play a role in CRC-Sm pathogenesis through the dysregulation of apoptosis by alteration the expression pattern of Bcl-2 protein differently from CRC-NSm suggesting a different biological behavior