C-Myb and Bcl-x overexpression predicts poor prognosis in colorectal cancer: Clinical and experimental findings

The aim of this study was twofold: to assess the rela-tionship between c-Myb and Bcl-x expression and toevaluate the prognostic significance of their expres-sion in colorectal carcinoma (CRC) patients. Analysisof tumors from 91 CRC patients for expression ofc-Myb and Bcl-x revealed a significant relationshipbetween these two proteins. Kaplan-Meier’s analysisshowed an increased risk of relapse and death inpatients whose tumor specimens displayed highc-Myb levels and Bcl-x positivity. Similar results werealso observed excluding Dukes’ D patients. Molecularanalysis using three c-Myb-overexpressing LoVoclones indicated that c-Myb overexpression was ac-companied by up-regulation of Bcl-xL protein andmRNA. Tumors originating from these clones injectedin nude mice were significantly larger than thoseformed in mice injected with parental or vector-trans-fected LoVo cells. Moreover , tumors derived from pa-rental and control vector-transfected but not fromc-Myb-overexpressing LoVo cells showed high fre-quency of apoptotic cells. These results provide directevidence of an association between c-Myb and Bcl-xexpression and suggest that expression of both mol-ecules might be a useful prognostic marker in CRC.