Association of galectin-3 expression with melanoma progression and prognosis.

Aims: Galectin-3 plays an important role in adhesion, proliferation, differentiation, angiogenesis and metastasis in multiple tumours. To investigate the role of galectin-3 in melanoma pathogenesis we examined the expression of galectin-3 in melanocytic lesions and analysed the correlation between galectin-3 expression and clinicopathologic factors including patient survival and BRAF mutation status.

Methods: We evaluated the expression of galectin-3 in 53 cases of benign naevi, 31 cases of dysplastic naevi, 59 in-situ melanomas, 314 cases of primary melanoma and 69 metastatic melanomas using tissue microarray and immunohistochemistry.

Results: Marked differences in expression of galectin-3 were seen between different categories of melanocytic lesions (ANOVA p<0.0001). An increase in expression of galectin-3 between benign naevi and thin primary melanomas and a progressive decrease in expression between thin primary melanomas and thicker melanomas or metastatic melanomas was seen. Strong galectin-3 expression was associated with improved overall survival (p=0.002 and p=0.0002 for cytoplasmic and nuclear expression, respectively) and melanoma-specific survival (p=0.017 and p=0.003 for cytoplasmic and nuclear expression, respectively). A multifactorial Cox regression analysis suggested that galectin-3 expression was an independent prognostic marker for overall survival in melanoma (risk ratio 0.73, 95% CI 0.547-0.970, p=0.031 for cytoplasmic expression and risk ratio 0.76, 95% CI 0.587-0.985, p=0.036 for nuclear expression). No association between galectin-3 expression and BRAF mutation status was observed.

Conclusion: This study suggests that galectin-3 is a marker of progression in melanocytic lesions and a novel prognostic marker in primary melanoma.