Diagnostic, prognostic and therapeutic potential]

Galectins in prostate and bladder cancer: tumorigenic roles and clinical opportunities

Advanced prostate and bladder cancer are two outstanding unmet medical needs for urological oncologists. The high prevalence of these tumours, lack of effective biomarkers and limited effective treatment options highlight the importance of basic research in these diseases. Galectins are a family of β-galactoside-binding proteins that are frequently altered (upregulated or downregulated) in a wide range of tumours and have roles in different stages of tumour development and progression, including immune evasion. In particular, altered expression levels of different members of the galectin family have been reported in prostate and bladder cancers, which, together with the aberrant glycosylation patterns found in tumour cells and the constituent cell types of the tumour microenvironment, can result in malignant transformation and tumour progression. Understanding the roles of galectin family proteins in the development and progression of prostate and bladder cancer could yield key insights to inform the clinical management of these diseases.

Diagnostic and Prognostic Significance of Serum and Tissue Galectin 3 Expression in Patients with Carcinoma of the Bladder

BACKGROUND

Galectins are group of proteins found in the cytoplasm, nucleus, cell surface and extracellular matrix. Galectin 3 (Gal-3) displays pathological expression in a variety of processes such as tumorigenesis.

PATIENTS AND METHOD

70 patients classified into the control group, cystitis group, transitional cell carcinoma group, and squamous cell carcinoma group were enrolled in this study which aimed to detect the serum level and the intensity of tissue expression of Gal-3.

RESULTS

Both serum level and tissue expression of Gal-3 were statistically higher in bladder cancer patients compared to the other groups. Gal-3 level expression increased from low to high grade urothelial tumors, with a statistically significant increase of its level and expression between muscle invasive and non-muscle invasive Ta urothelial tumors.

CONCLUSION

The serum Gal-3 level is sensitive and specific for the diagnosis of bladder cancer. The prognostic significance of tissue expression is to be confirmed.

Galectin 3 for the diagnosis of bladder cancer

OBJECTIVE

To evaluate serum levels of galectin-3 (G-3) in patients with bladder cancer and a control group, as a potential diagnostic and prognostic serum tumour marker.

PATIENTS AND METHODS

Between November 2012 and January 2013, 55 patients (median age 58 years) were enrolled into three groups, i.e., a control, those with transitional cell carcinoma (TCC) or those with squamous cell carcinoma (SCC). The serum G-3 level was measured the night before cystoscopy. The levels of G-3 levels were correlated with tumour type, stage and grade, and in relation to levels in normal urothelium. The results were analysed statistically using the Mann-Whitney U-test, the Kruskal-Wallis test and the receiver operating characteristic curve, as appropriate.

RESULTS

The median serum G-3 level was 100, 720 and 920 pg/mL in the control, TCC and SCC groups, respectively, with very significantly greater G-3 levels in both the TCC and SCC groups than in the control group. Patients with high-grade TCC had a statistically significantly greater serum G-3 level than those with low-grade tumours, as did those with muscle-invasive TCC than those with Ta tumours.

CONCLUSIONS

The level of G-3 can aid as a diagnostic marker in patients with either TCC or SCC of the bladder, but the prognostic significance of G-3 remains to be confirmed.

Galectin-3 expression in prostate cancer and benign prostate tissues: correlation with biochemical recurrence

BACKGROUND

Galactin-3 is a cell adhesion molecule involved in tumor progression. Our aim was to examine Gal-3 expression in tumor, benign tissue adjacent to the tumor (adjacent-benign) and benign prostate specimens and correlated it with biochemical recurrence.

MATERIALS AND METHODS

Tissue microarrays were prepared from 83 tumor, 78 adjacent-benign and 75 benign tissues obtained from 83 patients undergoing prostatectomy for clinically localized prostate cancer. Tissues were stained using a Gal-3 antibody and immunohistochemistry. The staining was graded between 0 and 300 depending upon staining intensity and the area of staining. In 37 patients on whom there was follow-up (Mean: 57.8 months; Median: 68 months), staining intensity was correlated with biochemical recurrence.

RESULTS

Gal-3 showed both nuclear and cytoplasmic localization in benign, adjacent-benign and tumor tissues. Median Gal-3 staining scores significantly decreased from benign (192.5) to adjacent-benign (148.8 p = 0.007) and to tumor (108.8; p < 0.0001) tissues. In univariate analysis, age (p = 0.028), Gleason sum (p = 0.007), T stage (p = 0.011), seminal vesicle invasion (p = 0.009), pre-operative prostate-specific antigen (p = 0.045) and Gal-3 staining in tumor tissues (0.018) significantly correlated with biochemical recurrence. In multivariate analysis, Gal-3 expression in tumor (p = 0.04), adjacent-benign (p = 0.037) and benign (p = 0.005) tissues significantly correlated with biochemical recurrence. Gal-3 staining in tumor tissues had 91.7 % sensitivity, 64 % specificity and 73 % accuracy in predicting biochemical recurrence.

CONCLUSIONS

This is the first study that showed a decreasing gradient of Gal-3 expression in benign, adjacent-benign and tumor tissues. Gal-3 expression may be useful in predicting biochemical recurrence.

Changes in the expression and subcellular distribution of galectin-3 in clear cell renal cell carcinoma

Background

Clear cell renal cell carcinoma, a solid growing tumor, is the most common tumor in human kidney. Evaluating the usefulness of β-galactoside binding galectin-3 as a diagnostic marker for this type of cancer could open avenues for preventive and therapeutic strategies by employing specific inhibitors of the lectin. To study a putative correlation between the extent of galectin-3 and the development of clear cell renal cell carcinoma, we monitored the quantity and distribution of this lectin in tissue samples from 39 patients.

Methods

Galectin-3 concentrations in normal, intermediate and tumor tissues were examined by immunofluorescence microscopy and on immunoblots with antibodies directed against galectin-3 and renal control proteins. The cell nuclei were isolated to determine quantities of galectin-3 that were transferred into this compartment in normal or tumor samples.

Results

Immunofluorescence data revealed a mosaic pattern of galectin-3 expression in collecting ducts and distal tubules of normal kidney. Galectin-3 expression was significantly increased in 79% of tumor samples as compared to normal tissues. Furthermore, we observed an increase in nuclear translocation of the lectin in tumor tissues.

Conclusions

Our data indicate that changes in the cellular level of galectin-3 correlate with the development of clear cell renal cell carcinoma, which is in line with previously published data on this specific type of tumor. In most of these studies the lectin tends to be highly expressed in tumor tissues. Furthermore, this study suggests that the increase in the proportion of galectin-3 affects the balance from a cytosolic distribution towards translocation into the nucleus.