Aberrantly Elevated Galectin-3 and Carbohydrate Antigen Tn Expression in Fine Needle Aspiration Specimens of Pancreatic Ductal Adenocarcinoma but Not Neuroendocrine Tumors
Momin T Siddiqui, Kun Jiang, Sean R Stowell, Richard D Cummings, Cynthia Cohen. Emory University School of Medicine, Atlanta, GA
Background: Galectin-3, a beta-galactoside-binding protein, has been implicated in tumorigenesis and tumor progression. However, its impact on pancreatic ductal adenocarcinoma (PDAC) remains controversial, ranging from tumor-suppressive to tumor-promotion properties and negative prognostic effects. Although Galectin-3 was shown to promote metastasis in PDAC cell lines, clinical evidence is still lacking. In addition, its applicability in pancreatic fine needle aspiration specimens has never been tested. Tn, a mucin-like protein glycan, is aberrantly expressed in malignant neoplasms, while minimally expressed in normal tissues. The functional role of Tn and the mechanism by which Tn promotes tumorigenesis remains unclear. We investigated the expression of Galectin-3 and Tn in PDAC, pancreatic neuroendocrine tumors, and non-tumor pancreatic tissues, to evaluate their potential diagnostic values.
Design: Galectin-3 and Tn levels were evaluated in 46 PDAC, 5 neuroendocrine tumors, and 8 non-neoplastic pancreatic fine needle aspiration (FNA) cell blocks (CB) by immunohistochemistry. Membranous and granular cytoplasmic staining of Galectin-3 or Tn (3+ and >10% cells) were considered positive. The data were analyzed by statistical analysis.
Results: Forty-four and 43 of 46 PDAC CB demonstrated tumor-specific Galectin-3 positivity (sensitivity 95.7%; specificity 87.5%; p<0.001) and Tn staining (sensitivity 93.5%; specificity 87.5%; p<0.001), respectively. In contrast, only 12.5% (1/8 and 1/8) non-neoplastic cases showed focal moderate Galectin-3 or Tn staining (2+, p<0.001). Furthermore, no positivity for Galectin-3 or Tn was detected in neuroendocrine tumors.
|Pancreatic FNAs (number)||Galectin-3 +++||Tn +++|
|PDAC (46)||44 (95.7%)||43 (93.5%)|
|Neuroendocrine tumors (5)||0 (0%)||0 (0%)|
|Non-tumor (8)||1 (12.5%)||1 (12.5%)|