Hepatocellular carcinoma (HCC) is a major worldwide health problem and a cancer with increasing incidence in the United States mainly due to hepatitis C viral (HCV) infections. Approximately 10-30% of HCV carriers develop cirrhosis; patients with cirrhosis have an annual risk of 1-2% for developing HCC and their prognosis is generally poor. The slow development and late detection of HCC suggest that the identification of biomarkers of disease progression and early detection are needed. Glycosylation is the most common post-translational modification of secreted proteins. Alterations in protein glycosylation are associated with different cancers, including HCC. We hypothesized that the site-specific glycosylation of proteins in HCC patients would differ from that of patients with liver cirrhosis and healthy people. Haptoglobin is a liver secreted glycoprotein with four N-glycosylation sites. Its main function is to bind free hemoglobin released by intravascular hemolysis; haptoglobin prevents the loss of iron and subsequent kidney damage. We used mass spectrometry to define site specific glycoforms of haptoglobin in the serum of 15 patients with HCC, 20 patients with liver cirrhosis due to HCV etiology and 15 disease free controls. We used selected reaction monitoring (SRM) quantification to quantify the changes in N-glycosylation. Quantification of 7-10 glycoforms per glycosylation site (approximately 30 glycoforms in total), revealed that site specific glycosylation of haptoglobin is altered in the diseased liver and is associated with liver damage and the presence of HCC. Results also indicated an increase of fucosylated glycans among patients with liver disease. In this pilot case-control study we demonstrated the development of site specific haptoglobin glycoform in the progression of liver disease. If confirmed by larger and prospective studies, site specific glycosylation of haptoglobin and other proteins, in general, could be used as a marker of HCC risk.

Citation Information: Cancer Prev Res 2010;3(12 Suppl):B19.