Consistent with prior studies, the pattern of GLUT-1 clearly indicated that a large part of its expression is presumably unrelated to hypoxia.
The expression pattern of GLUT-1, as described in the present study, may neither be related to hypoxia nor to "aerobic glycolysis", i.e., the Warburg effect.
These findings underscore our interpretation of an "inverse" expression pattern of GLUT-1 and a "typical", hypoxia-related pattern of CA IX.
Consistent with these latter data, the present study describes a largely inverse, i.e., hypoxia-independent expression pattern of GLUT-1 and a diminished expression of CA IX in invasive tumors compared to dysplasias and non-malignant vulvar squamous epithelium.
The hypothesis is that the expression pattern of avian GLUTs differs from mammals to maintain the high plasma glucose levels of birds and insulin insensitivity.
In this study, we report for the first time the level and pattern of expression of Glut-1, as a potential endogenous marker of hypoxia, in rectal carcinoma and relate the level of expression to outcome.
Results of this analysis showed that most of the (antigen-positive) tumours exhibited the expected pattern of expression of GLUT and CA IX beyond a mean distance of approx. 80 μm (76 μm for GLUT-1 and 83 μm for CA IX) from the nearest microvessels in subregions of the biopsies.
The pattern of HIF-1α, Glut-1 and CAIX was noted as purely diffuse (throughout the tumour without emphasis on areas with necrosis, thought to be due to non-hypoxic stimuli), perinecrotic (only positive staining around a necrotic area, thought to be hypoxia induced) or a combination of these two ("mixed").
This could account for the immunostaining patterns for Glut-1 and CAIX.
All members of GLUT family isolated from humans possess 12 transmembrane (TM) α-helices [ 9], structural patterns that are also present in some glucose transporters from Insecta [ 29].
Inhibition of Glut function reduces glucose uptake.
