Proteomic analysis of pancreatic secretory trypsin inhibitor/tumor-associated trypsin inhibitor from urine of patients with pancreatitis or prostate cancer.

The development of proteomic methods, especially mass spectrometry, has brought new possibilities to tumor marker research. Pancreatic secretory trypsin inhibitor (PSTI), a common known biomarker for various malignancies, occurs on genetic variants that we are able to detect at the protein level with proteomic techniques using immunoaffinity capture prior to liquid chromatography-mass spectrometry (LC-MS). We also show that PSTI can be detected in urine from cancer patients using a two-step peptide enrichment technique and LC-MS. These results show that tumor-associated peptides can be detected in urine by proteomic techniques.