Coagulation disorders and tumor markers in the diagnosis of pancreatic cancer

Peptide and protein assays using customizable bio-affinity arrays combined with ambient ionization mass spectrometry

High-throughput identification and quantification of protein/peptide biomarkers from biofluids in a label-free manner is achieved by interfacing bio-affinity arrays (BAAs) with nano-electrospray desorption electrospray ionization mass spectrometry (nano-DESI-MS). A wide spectrum of proteins and peptides ranging from phosphopeptides to cis-diol biomolecules as well as thrombin can be rapidly extracted via arbitrarily predefined affinity interactions including coordination chemistry, covalent bonding, and biological recognition. An integrated MS platform allows continuous interrogation. Profiling and quantitation of dysregulated phosphopeptides from small-volume (∼5 μL) serum samples has been successfully demonstrated. As a front-end device adapted to any mass spectrometer, this MS platform might hold much promise in protein/peptide analysis in point-of-care (POC) diagnostics and clinical applications.

Customizable bio-affinity arrays were interfaced with ambient ionization mass spectrometry for high-throughput assays of protein/peptide biomarkers in biofluids.

Advances in biomarker research for pancreatic cancer

Pancreatic cancer (PC) is a leading cause of cancer related deaths in United States. The lack of early symptoms results in latestage detection and a high mortality rate. Currently, the only potentially curative approach for PC is surgical resection, which is often unsuccessful because the invasive and metastatic nature of the tumor masses makes their complete removal difficult. Consequently, patients suffer relapses from remaining cancer stem cells or drug resistance that eventually lead to death. To improve the survival rate, the early detection of PC is critical. Current biomarker research in PC indicates that a serum carbohydrate antigen, CA 19-9, is the only available biomarker with approximately 90% specificity to PC. However, the efficacy of CA 19-9 for assessing prognosis and monitoring patients with PC remains contentious. Thus, advances in technology and the detection of new biomarkers with high specificity to PC are needed to reduce the mortality rate of pancreatic cancer.

Proliferation tissue polypeptide antigen distinguishes malignant mucinous cystadenocarcinomas from benign cystic tumors and pseudocysts

BACKGROUND

Cystic lesions of the pancreas include inflammatory pseudocysts, serous cystadenomas, and mucinous cystic tumors, some of which are malignant. Previous studies have shown that malignant mucinous tumors differ from benign pancreatic cysts in proliferative activity, secretion of tumor markers, and expression of growth factor receptors. Analysis of aspirated cyst fluid for tumor markers, viscosity, and cytologic examination has been proposed as an aid to preoperative differential diagnosis. Tissue polypeptide antigen (TPA) is a soluble proliferation antigen produced by rapidly dividing tissues, including conventional ductal pancreatic carcinoma. TPA levels in pancreatic cyst fluids have not been reported.

METHODS

Tissue polypeptide antigen levels were determined in 46 pancreatic cyst fluids using a commercial immunoassay technique.

RESULTS

Mucinous cystadenocarcinomas exhibited significantly higher levels of cyst fluid TPA than benign cystic lesions, including pseudocysts, serous cystadenomas, and benign mucinous cystadenomas (mean 910,672 U/mL, median 300,900 U/mL, range 16,600 to 4,210,000 U/mL for malignant mucinous cystadenocarcinomas; versus mean 16,082 U/mL, median 2,455 U/mL, range 0 to 155,000 U/mL for benign cystic lesions considered as a group; P < 0.0002). In 75% of the malignant cysts, the TPA values were in excess of 100,000 U/mL. Pseudocysts exhibited the lowest TPA levels (mean 2,108 U/mL, median 604 U/mL, range 0 to 20,240 U/mL) and were significantly lower than the values observed in cystic tumors (P < 0.0005). Serous and benign mucinous tumors had intermediate levels of TPA.

CONCLUSIONS

Elevated levels of the proliferation antigen TPA in malignant pancreatic cysts correlate with earlier observations of increased proliferative activity and overexpression of growth factor receptors in these tumors. The TPA measurement may be a useful addition to previously reported cyst fluid markers to aid in preoperative differential diagnosis. Markedly elevated or very low values indicate a malignant or benign cyst, respectively.