Prognostic value of galectin-1 and galectin-3 expression in localized urothelial bladder cancer.

BACKGROUND

Galectin-1 (Gal-1) and Galectin-3 (Gal-3) are carbohydrate binding proteins with a wide range of biological activity, including regulation of cellular adhesion, proliferation, and apoptosis in solid tumors. Prior small studies have reported that Gal-3 expression is associated with progression of disease in urothelial carcinoma (UC), from non-muscle invasive UC progression to muscle invasive UC. We assessed Gal-1 and Gal-3 protein expression H-score utilizing a tissue microarray (TMA) created from 301 cystectomy specimens.

METHODS

Immunohistochemistry for Gal-1 and Gal-3 was performed on TMA generated from tumor blocks from chemotherapy naïve cystectomy specimens. The variable of interest, H-score, was defined as the product of the percentage of cells staining positive (0-100) and intensity score (0-3) scored by a single pathologist. Survival end points were analyzed using Kaplan-Meier and Cox Proportional Hazards methods. Clinical data including Charlson Comorbidity Index (CCI), pathologic tumor (T) stage, tumor size, node stage, and surgical margins, were included in multivariable analysis.

RESULTS

We found that Gal-1 and Gal-3 expression correlated with intratumoral T stage (median Gal-1 H-score was 0 across non-invasive tissue types and 200 in invasive, P<0.01 and median Gal-3 score was 270 across non-invasive tissue types and 70 in invasive, P<0.01). However, the highest intratumoral H-score per cystectomy core did not independently predict for recurrence-free survival (RFS) (Gal-1: HR =1.02, P=0.44, Gal-3: HR =1.01, P=0.65) or OS (Gal-1: HR =1.02, P=0.44, Gal-3: HR =1.01, P=0.72) in this cohort. Significant intratumoral heterogeneity was present for both Gal-1 and Gal-3, with an average difference between the highest and lowest H score was 95 for Gal-1 and 109 for Gal-3 for cystectomy specimens with more than one biopsy.

CONCLUSIONS

Gal-1 and Gal-3 H-score per bladder did not independently predict for RFS or OS. Intra-tumoral Gal-1/Gal-3 heterogeneity complicates the use of Gal-1 and Gal-3 expression as a prognostic biomarker. Future studies should consider the evaluation of serum and urinary galectins as an approach to mitigate tumor heterogeneity.