Inventors:
Bert Vogelstein - Baltimore MD, US
Qing Wang - Parkville MD, US
Akhilesh Pandey - Ellicott city MD, US
Kenneth W. Kinzler - Baltimore MD, US
Nickolas Papadopoulos - Towson MD, US
Assignee:
THE JOHNS HOPKINS UNIVERSITY - Baltimore MD
International Classification:
G01N 33/68
Abstract:
Altered protein products resulting from somatic mutations are directly identified and quantified by mass spectrometry. The peptides expressed from normal and mutant alleles are detected by Selected Reaction Monitoring (SRM) of their productions using a triple quadrupole mass spectrometer. As a prototypical example of this approach, we quantify the number and fraction of mutant Ras protein present in cancer cell lines. There were an average of 1.3 million molecules of Ras protein per cell and the ratio of mutant to normal Ras proteins ranged from 0.49 to 5.6. Similarly, we detected and quantified mutant Ras proteins in clinical specimens such as colorectal and pancreatic tumor tissues as well as in pre-malignant pancreatic cyst fluids. These methods are useful for diagnostic applications.