Objectives: The prognosis of pancreatic cancer is still very poor, and the ability to detect pancreatic cancer in high-risk groups at an early stage is therefore essential for improving its long-term survival. The purpose of this study was to explore specific biomarkers that can differentiate pancreatic cancer-associated diabetes from type 2 diabetes, for the early detection of pancreatic cancer.
Methods: From January 2006 to July 2008, 102 peripheral blood samples were collected from 25 patients diagnosed with pancreatic cancer and diabetes, 27 patients with pancreatic cancer without diabetes, 25 patients with diabetes mellitus >5 years, and 25 healthy controls. Thirty-two samples were used in microarray experiments to find differentially expressed genes specific for pancreatic cancer-associated diabetes. The results were further validated by quantitative real-time PCR for 101 blood samples. Protein expression of selected genes in serum and tissues was also detected.
Results: Using microarray analysis, we found 58 genes to be unique in patients with pancreatic cancer-associated diabetes, including 23 upregulated genes and 35 downregulated genes. Eleven upregulated genes were further validated by RT-PCR, and two of these genes-vanin-1 (VNN1) and matrix metalloproteinase 9 (MMP9)-were selected for logistic regression analysis. The combination of VNN1 and MMP9 showed the best discrimination of pancreatic cancer-associated diabetes from type 2 diabetes. The protein expression of MMP9 and VNN1 was in accordance with the gene expression.
Conclusions: Our results indicate that the combination of VNN1 and MMP9 may be used as a novel blood biomarker panel for the discrimination of pancreatic cancer-associated diabetes from type 2 diabetes.