Relationships of P53 and Bak with EPO and EPOR in human colorectal cancer.

Background: EPO (erythropoietin) counteracts p53-dependent apoptosis. EPO, which acts via its receptor EPOR, protects cells and inhibits apoptosis in normal cells and some cancer tissues by severe down-regulation of Bak. We aimed to investigate the relationship between p53 and Bak expression and EPO and EPOR in human colorectal carcinomas.

Materials And Methods: The expression of p53 was compared with Bak, EPO and EPOR in 96 colorectal carcinomas by means of immunohistochemistry.

Results: Purely nuclear p53 was significantly higher expressed in the moderately differentiated cancers in comparison with the poorly differentiated ones (p=0.007). P53 expression did not correlate with cytoplasmic markers: Bak, EPO and EPOR, but EPO and EPOR were significantly associated with Bak expression (p<0.001, r=0.524 and p<0.001, r=0.455, respectively). p53 expression was not associated with disease-free survival during the 3 years and 9 months long follow-up.

Conclusion: A complete disruption of association between p53 and Bak could impair of p53-dependent apoptotic pathway that involves Bak. The relationship of Bak with EPO and EPOR is evidence of their co-expression suggesting competition between EPO mediated cell survival and Bak associated apoptosis in colorectal carcinomas.