Galectin-3 and S100A9: Novel Diabetogenic Factors Mediating Pancreatic Cancer–Associated Diabetes

Abstract

OBJECTIVE Pancreatic cancer–associated diabetes (PCDM) is a paraneoplastic phenomenon accounting for 1% of new-onset diabetes. We aimed to identify the mediators of PCDM and evaluate their usefulness in distinguishing PCDM from type 2 diabetes. RESEARCH DESIGN AND METHODS Secreted proteins of MIA PaCa-2 cells were identified by proteomics, and those with ≥10-fold overexpression in transcriptome analysis were assessed by bioinformatics and glucose uptake assay to identify candidate factors. Expression of factors was compared between tumors with and without PCDM by immunohistochemistry. Serum levels were measured in a training set including PC with and without PCDM, type 2 diabetes, pancreatitis, other pancreatic/peripancreatic tumors, and control subjects (n = 50 each). Cutoff values for differentiation between PCDM and type 2 diabetes from the training set were validated in a test set (n = 41 each). RESULTS Galectin-3 and S100A9 were overexpressed in tumors with PCDM and dose-dependently suppressed insulin-stimulated glucose uptake in C2C12 myotubes. In the training set, serum galectin-3 and S100A9 levels were exclusively increased in patients with PCDM and distinguished PCDM from type 2 diabetes (area under the curve [AUC] galectin-3: 0.73 [95% CI 0.64–0.83]; S100A9: 0.79 [95% CI 0.70–0.87]). Similar results were observed in the test set (AUC galectin-3: 0.83 [95% CI 0.74–0.92]; S100A9: 0.77 [95% CI 0.67–0.87]), with sensitivity and specificity 72.1% and 86.1%, respectively, for galectin-3 and 69.8% and 58.1% for S100A9 in differentiating between PCDM and type 2 diabetes. CONCLUSIONS Galectin-3 and S100A9 are overexpressed in PCDM tumors and mediate insulin resistance. Galectin-3 and S100A9 distinguish PCDM from type 2 diabetes in subjects with new-onset diabetes.