Objectives: It has previously been shown that glucose uptake and use is more prevalent in carcinomas than in normal cells and tissues. We hypothesized that human erythrocyte glucose transporter (Glut-1) expression is increased in bladder transitional cell carcinoma (TCC) and that the grade of expression might correlate with the degree of malignancy.
Methods: Immunostaining of Glut-1 protein was studied in normal bladder (5 cases), benign papilloma (10 cases), superficial tumor (48 cases), and invasive tumor (31 cases) tissue. The immunoreactivity grading system used was as follows: absence of immunoreactivity in tumor cell = 0; less than 10% of the tumor cells immunoreactive = 1+; 10% to 50% of the tumor cells immunoreactive = 2+; and greater than 50% of the tumor cells immunoreactive = 3+.
Results: Immunostaining of Glut-1 protein was not expressed in the normal bladder or benign papilloma samples, but it was expressed in 63.0% (46 of 73) of the TCC samples. In the pattern of expression of Glut-1 protein, superficial TCC was stained focally, but invasive TCC was stained diffusely in the tumor nests. The grade of Glut-1 protein expression increased more significantly in the invasive TCC than in the superficial TCC samples (P = 0.002) and more significantly in the high nuclear grade than in the low nuclear grade samples (P = 0.007). In the superficial TCC samples, the bladder tumor recurrence rate did not significantly correlate with Glut-1 protein expression (P = 0.40).
Conclusions: Our results suggest that the Glut-1 protein is not expressed in normal bladder mucosa and benign lesions, that Glut-1 protein expression is strongly associated with neoplastic progression in bladder TCC, and that Glut-1 expression does not correlate with the recurrence rate in superficial bladder TCC.