Galectin-3: differential expression between small-cell and non-small-cell lung cancer

Aims: To compare the histological expression of galectin-3 in different lung cancers, including small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). Lung cancer is the leading cause of cancer deaths in the UK. Galectin-3 is a beta-galactoside binding protein with a controversial role in malignant transformation. SCLC metastasizes early and is initially chemosensitive; NSCLC metastasizes later, offering the chance of surgical cure, but is much less chemosensitive. Mixed tumours present a diagnostic and therapeutic problem, with a poorer response to therapy. Insight into the cellular mechanisms that govern metastasis and chemoresistance will profoundly influence the future management of this disease. Methods and results: In this study the histological expression of galectin-3 was assessed in a panel of lung tumour specimens, using the indirect streptavidin-biotin method. A striking difference in galectin-3 expression was observed between tumours, with high expression in NSCLC (42/47 samples) and low expression in SCLC (negative in 13/18, weak in 5/18). Conclusion: This differential expression of galectin-3 between histological types of lung carcinoma suggests that galectin-3 may have an important influence on tumour cell adhesion, apoptosis and the response of tumours to chemotherapy.