Galectin-3 and proliferating cell nuclear antigen (PCNA) expression in papillary thyroid carcinoma.

To examine the relationship between galectin-3 and cell proliferation in thyroid tumor tissue. Galectin-3, a beta-galactoside binding protein, has recently been recognized as a promising molecular marker of thyroid malignancy, due to its high expression in thyroid carcinomas and absence from normal or benign thyroid tissue. However, its exact role in thyroid tumor biology is still unknown.We examined the relationship between galectin-3 and cell proliferation by comparative immunostaining for galectin-3 and proliferating cell nuclear antigen (PCNA) in paraffin-embedded tissues from 126 cases of papillary thyroid carcinoma.Positive cytoplasmic immunostaining for galectin-3 was found in 115 (91.3%) cases. Nuclear staining for PCNA was detectable in 93 (74.4%) cases. A low level of PCNA staining (less than 10% positive cells) was found in 36 (28.6%) cases, moderate staining for PCNA (more than 10% but less than 30% positive cells) in 35 cases (27.8%), while highly increased PCNA expression (more than 30% positive cells) was found in 32 (25.4%) cases. Moderate or strong galectin-3 expression, found in 99 cases, was associated with highly increased PCNA staining in 28.3% of them but with no detectable PCNA expression in 24.3% of them.These results suggest that overexpression of galectin-3 is not clearly related to proliferative activity of papillary thyroid carcinoma cells as assessed by PCNA immunostaining.