O-PTM Biomarkers

 

Discovery of novel cancer serum biomarkers based on aberrant post-translational modifications of O-glycoproteins, O-PTM-Biomarkers, and their application to early detection of cancer

Cancer is a leading cause of death in developed countries, including Europe with one in three people being affected.

Early detection accomplished through an efficient screening program remains the most promising approach to improve the long-term survival of cancer patients.

Therefore there is a pressing need for the development of biomarkers, which detect the early changes that lead to overt malignancy, particularly for cancers where clinical symptoms only appear when the cancer has progressed, and patients have poor survival (eg. ovarian, pancreatic, and lung cancer). This project addresses this problem.

Our proposal combines two unique features:

i) large serum collections having the potential for evaluation of diagnostic serum biomarkers, with high statistical power, and

ii) a unique approach involving both highly specific immuno-detection of cancer-associated Post-Translationally Modified (PTM) glycoproteins in serum and detection of immunity to these. Our approach to identifying diagnostic biomarkers, useful for early detection of cancer, is based on distinct cancer-associated changes in one of the most abundant post-translational modification of proteins namely O-glycosylation (O-PTM). Carcinomas characteristically express poorly O-glycosylated glycoproteins, including membrane mucins such as MUC1 and MUC16. These glycoproteins are released into serum and are the targets of the current biomarker assays CA15-3 and CA125. The composition and density of attached O-glycans on glycoproteins are changed in carcinomas, and we have developed strategies to screen and selectively immuno-probe these changes in a protein and O-glycan specific manner. We have demonstrated that composite cancer-associated glycopeptide epitopes (often repeated) appear which are specific for both the core protein and the novel glycan.

 

These novel epitopes distinguish the cancer glycoprotein from the normal counterpart and induce auto-antibodies which represent potential biomarkers as well as the actual cancer glycoprotein which can be shed into serum.

The main objectives of this project are therefore:-

 

  • To identify evaluate and validate an O-PTM auto-antibody signature as an early diagnostic biomarker for breast ovarian, pancreatic and lung cancers using two unique serum banks and novel microarray technology.

 

  • To develop and validate ELISA-type assays for cancer specific glycoforms of    MUC1 and MUC16 for A. patient management B. screening for the above cancers

 

These objectives relate directly to the call in that they:

  • Translate the data on the molecular genetics and molecular pathology of O-PTM in cancer, which Participants in this Consortium have accumulated, into developing an evidence-based strategy to identify early diagnostic biomarkers for cancer.

 

  • Use exclusively patients’ serum from unique banks with predictive power.

 

  • Utilize a unique glycopeptide micro-array technology where the synthesis of the glycopeptides is accomplished in vitro using recombinant glycosyl-transferases (oncogenomics)

 

  • Validate the biomarkers in the Clinical Laboratory

We have established milestones described in B1.3 that will allow the progress of the project and achievement of the objectives to be efficiently monitored.