[1842] Galectin-3, STn and Tn: Expression Profile in Pancreatic Neoplasms and Gastrointestinal Stromal Tumors

Kun Jiang, Cynthia Cohen, Sean R Stowell, Richard D Cummings, Momin T Siddiqui. Emory University School of Medicine, Atlanta, GA

Background: Dysregulated levels of glycan-binding proteins, especially Galectin-3, have been identified in a spectrum of malignancies. However, its contribution to the pathogenesis and progression of cancers awaits characterization. Aberrant expression of glycan antigens Tn and sialylated STn have also been implicated in tumors. However, the potential diagnostic utility of these molecules in pancreatic neoplasms and gastrointestinal stromal tumors (GIST) has not been characterized. This study aims to assess their expression and to determine their diagnostic utility in these neoplasms.
Design: Galectin-3, Tn and STn were evaluated immunohistochemically in fine needle aspiration (FNA) cell blocks (CB) from: 1) 46 pancreatic ductal adenocarcinoma (PDAC), 2) 8 non-neoplastic pancreas, 3) 5 pancreatic neuroendocrine neoplasms (PNEN), and 4) 13 GIST. Membranous and granular cytoplasmic labeling (3+ and >10% cells) was considered positive. The data were analyzed by statistical analysis.
Results: Forty-four, 43, and 41 of 46 PDAC CB demonstrated tumor-specific Galectin-3 (sensitivity 95.7%; specificity 87.5%), Tn (sensitivity 93.5%; specificity 87.5%), and STn positivity (sensitivity 89.1%; specificity 87.5%), respectively. Adjacent non-neoplastic tissue showed either negativity or minimal levels of Tn and STn. In contrast, only 12.5% (1/8) non-neoplastic pancreas showed focal 2+ Galectin-3, Tn, or STn signal (p<0.001). Importantly, no positivity for Galectin-3, Tn or STn was detected in PNEN and GIST studied.

 Gal-3 +++Gal-3 -Tn +++Tn -STn +++STn -
PDAC (46)44 (95.7%)2 (4.3%)43 (93.5%)3 (6.5%)41 (89.1%)5 (10.9%)
Non-neoplastic pancreas (8)1 (12.5%)7 (87.5%)1 (12.5%)7 (87.5%)1 (12.5%)7 (87.5%)
Total (54)45944104212
P<0.001 for all 3 markers; Gal-3: Galectin-3

TypeGal-3 +++Gal-3 -Tn +Tn -STn +STn -
PNEN (5)0 (0%)5(100%)0 (0%)5(100%)0 (0%)5(100%)
GIST (13)0 (0%)13(100%)0 (0%)13(100%)0 (0%)13(100%)
Negativities in PNEN and GIST

Conclusions: Unique and significant expression of Galectin-3, Tn and STn is demonstrated in PDAC, with minimal to negative levels in adjacent non-tumor tissue and normal pancreas. This is in sharp contrast to their lack of immunoreactivity in PNEN and GIST. These data strongly suggest their crucial roles in the pathogenesis and diagnosis of PDAC, but not in PNEN and GIST. They can potentially be utilized in challenging cases to aid in diagnosis of PDAC.
Category: Pathobiology

Monday, March 4, 2013 1:00 PM

Poster Session II # 274, Monday Afternoon


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