Hepatocellular Carcinoma (HCC) is the fourth most common cancer in the world. The incidence and mortality rates for HCC are virtually identical, indicating that novel methods for the early detection of HCC are of utmost importance. Liver cirrhosis is the most important factor in the development of HCC. Since the incidence of HCC is expected to double over the next decade, a highly specific noninvasive test that can differentiate early HCC from cirrhosis could have major impact on survival of patients at high risk of developing this disease. We have developed a unique lectin array/mass spectrometry isotopic tag method for identifying potential glycoprotein markers of early stage hepatocellular cancer (HCC) versus cirrhosis in serum. Several markers have been identified in our previous work, some of which have now passed a first stage of EDRN blinded validation based on ELISA assays. In the work proposed herein, we plan to develop a MALDI QIT mass spec based assay of glycans from early HCC and cirrhosis and compare them to results from the ELISA based methods to improve the overall performance for detection of HCC. In this method, immunoaffinity precipitation is used to extract a target glycoprotein from serum, the glycans removed and then the glycans are profiled using MALDI QIT MS. This platform utilizes monoclonal antibodies to capture and isolate target serum glycoproteins on which alterations in glycan structure can be probed using a mass spec based technique. The captured glycoproteins are deglycosylated and the glycan groups rapidly analyzed using tandem mass spectrometry. The use of the antibody affinity selects a limited number of candidates thus simplifying the search for glycans that are specific to the disease state using mass spectrometry. In addition, it associates the glycan change to a specific protein in serum providing a high degree of selectivity for detection of the glycan change in each disease state. It will be shown that this mass spec based method is highly specific and can detect changes in glycan structure between early HCC and cirrhosis. The method can detect changes in glycan structure while the current standard ELISAs only detect quantitative changes in glycoprotein expression. The mass spec method can also use an MS/MS technique for multiplexed samples so that glycan patterns from several proteins can be discriminated and several assays can be run simultaneously. The mass spec and ELISA methods will be applied to blinded sets of samples provided by the EDRN to demonstrate the potential for identifying markers of early HCC based on a combination of changes in fucosylation levels and glycoprotein level of target proteins where novel glycoproteins will undergo validation in a phase 1 biomarker study followed by validation in a larger phase 2 study.
If this project is successful then it will result in identification of specific glycan structures from glycosylated proteins in patient serum that can distinguish early stage HCC from cirrhosis in phase 1 and phase 2 studies. This will be a major advance in the field if these potential markers pass the initial 2 phases based upon either a novel antibody/glycoprotein/MALDI QIT tandem mass spectrometry assay or by ELISA.
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