Prof. Peter James

Phospho-shotgun and SRM MS to diagnose cancer in heat stabilized tissue 

Professor Peter James began his career at the University of Oxford. After graduating, he pursued a PhD in Ernesto Carafoli’s lab at ETH in Zurich, where Peter was introduced to protein sequencing, peptide synthesis and mass spectrometry. He continued across the Atlantic, with post doc studies in San Francisco and a few years at Thermo Finnigan before returning to Switzerland and ETH. In 2001, he ended up in Lund, Sweden on Professor Sture Forséns advice and this is still his base. Today Professor James is at the Department of Immunotechnology, Lund University and heads a group of 15.

Cancer research and phosphoanalysis

Professor James´s research focuses on cancer, particularly oesophageal and breast cancer, and aims at using proteomics as a means to rapid and unquestionable diagnosis of tumor origin, characterization and prognosis. As most chemotherapies work as kinase inhibitors, detection of phosphorylation events are fundamental, and since phosphorylation sites change quickly, preservation of the tissue biopsy is critical. DNA repair enzymes and apoptosis factors are also quickly degraded and it is crucial to understand the true state of the protein composition of the sample. In conditions as Barrett’s disease, several biopsies are taken from the patient; hence the time from sampling to preservation for the various samples may vary, which is why the ideal scenario is immediate stabilization in the operating theatre.

Cancer diagnosis within the hour

When Professor James started taking clinical biopsies, he went to the operating room with liquid nitrogen in a thermos. Liquid nitrogen is dangerous and wasn’t appreciated by the research nurses, why it was banned from the operating room and the nurses instead had to exit the room to put each biopsy in a -80 freezer, then scrub in again to re-enter. Of course this was tedious and the research conducted difficult to implement. At this time, Professor James also served as scientific advisor to GE Healthcare and had heard rumors about a new technology. Heat stabilization was immediately accepted and appreciated by the nurses, as the instrument easily can be sterilized and brought into the room. The biopsy is dropped directly into a Maintainor Tissue card container by the surgeon and the nurses can stabilize the samples without risking contamination. Not only does heat stabilization enable direct preservation of biopsies in the theatre, it also does preserve the proteome. Professor James identified four times as many phosphopeptides in heat stabilized samples than in snap frozen in a comparative study. Professor James analyses his samples using phospho-shotgun and SRM mass spectrometry for his research and aims at being able to diagnose a cancer within an hour, i.e. while the patient is still on the operating table.

Stability of the sample

When talking to colleagues, Professor James promotes two key aspects to tumor sampling; you need to take multiple samples from the same tumor and you need to acknowledge degradation. Leena Liljedahl, a PhD student in Professor James´s group, studies N-glycosylated peptides in insulin treated murine kidney. The kidneys are sent to Leena in frozen state, and she then conducts heat stabilization prior to analysis. She uses a mass spectrometric method requiring relatively long cycles in room temperature and hence stability is extra important.  As always in research, low inter-sample variability is key and Leena states “that’s why I use Denator’s Stabilizor system”.

Publications from Prof. Peter James utilizing the Stabilizor technology

Impact of temperature dependent sampling procedures in proteomics and peptidomics - A characterization of the liver and pancreas post mortem degradome, B Scholz et al. Molecular and Cellular Proteomics, M900229-MCP200, January 28, 2010
Keywords: Mouse liver and pancreas, 2D-GE, mass spectrometry