GLUT1 and Bcl-xL in relation to erythropoietin in human colorectal adenocarcinomas.

Background/Aims: GLUT1 and EPO belong to so called hypoxia-associated markers, which exert cytoprotective actions in the hypoxia suffering cells. In oxygen deficiency Bcl-xL can also be up-regulated. Methodology: Therefore, we detected with immunohistochemistry and compared EPO with expressions of GLUT-1 and antiapoptotic protein Bcl-xL in 125 colorectal cancers. EPO correlated with GLUT-1 in all colorectal cancers (p<0.001, r=0.369). EPO expressions also associated with Bcl-xL (p<0.001, r=0.591) in all colorectal cancers. Results: EPO correlated with GLUT-1 and Bcl-xL in subgroups of different nodal status, grading, staging, histopathological type, tumor site, patients' age and gender. However, the statistically significant relationship between EPO and GLUT-1 or Bcl-xL was lost in case of shallower neoplastic extent (pT1+pT2), but it was sustained in subgroup of deeper invading cancers (pT3+pT4) (p<0.001, r=0.355 and p<0.001, r=0.585, respectively). Conclusions: High expression of hypoxia dependent proteins (EPO, GLUT-1) indicates hypoxia of examined tissues of colorectal cancers. Cooperation may be reflected among the studied proteins by correlations between hypoxia dependent proteins (EPO vs. GLUT-1). Concerning functional significance of these investigated factors, subsequent promotion of cell survival could be maintained thanks to mutual impact of EPO and Bcl-xL on cellular viability in hypoxic environment of colorectal cancer.