Investigation of possible endogenous hypoxia markers in colorectal cancer.
OBJECTIVE
We evaluated the potential of some recently proposed hypoxia markers, being monocarboxylic acid transporter 1 (MCT1), MCT4 and prolyl hydroxylase 2 (PHD2); and a more established hypoxia marker, glucose transporter-1 (GLUT-1), by testing the association with the exogenous marker pimonidazole.


MATERIALS AND METHODS
Paraffin embedded tumour sections of 20 colorectal cancer patients were stained for blood vessels together with either pimonidazole or carbonic anhydrase-IX (CA-IX) and single stained for MCT1, MCT4, GLUT-1, and PHD2. Expression of all markers was compared with expression of pimonidazole and micro-vessel density (MVD) and with disease-free survival (DFS) and overall survival (OS).


RESULTS
No correlation was found between the different intrinsic hypoxia markers tested and pimonidazole. A trend for high MCT1 expression in biopsies with low CA-IX expression was found (R = -0.45, p = 0.06) and also the expression of MCT1 was higher in tumours with a high MVD (R = 0.49, p = 0.04). The more advanced tumours showed a higher expression of GLUT-1 (p = 0.03). A low CA-IX expression in the tumour correlated with better DFS (p = 0.03) and related to better OS (p = 0.07).


CONCLUSION
Although none of the tested intrinsic hypoxia markers correlated with pimonidazole staining, we confirmed the important role of both GLUT-1 and CA-IX for a more advanced pTNM (pathological tumour-node-metastasis) stage and DFS respectively.