The goal of the investigation is to establish the relationship of altered tumor marker glycosylation to carcinogenesis and tumor growth. The chronic hepatitis virus infection to hepatocellular carcinoma (HCC) sequence is similar in humans and woodchucks (WC). Human and WC HCC AFP glycosylation is different from both newborn liver cell and hepadnavirus-infected hepatocyte AFP glycosylation, therefore, altered AFP glycosylation by HCC is not simply due to rapid hepatocyte proliferation, high AFP secretion rates or hepadnavirus infection of hepatocytes.
The specific aims are to determine when during viral hepatocarcinogenesis altered AFP glycosylation is first detectable, if there are HCC-specific AFP glycoforms, the HCC AFP glycosylation variability, the number of HCC AFP glycosylation variants and to compare WC HCC AFP glycoforms to human HCC glycoforms. The investigation will increase our knowledge of a minimally-invasive experimental system suitable for serial clinical and basic studies of changes in tumor-secreted protein glycosylation during carcinogenesis and tumor growth. WC AFP glycoforms present during fetal/newborn growth, pregnancy and fall/winter will be compared to those present during pathological states. WC AFP glycoforms in woodchuck hepatitis virus (WHV)-free and WHV-infected newborns will be identified. Serial studies of AFP glycoforms in sera of individual WC at birth, during acute WHV infection, WHV-associated hepatocarcinogenesis and HCC growth will be performed. AFP glycosylation will be related to tumor growth rates (ultrasound) and to histologic changes during hepatocarcinogenesis. The effect of human delta virus-induced hepatitis in WC on AFP glycosylation will be determined. AFP glycoforms will be identified by lectin-affinity chromatography using 8 lectins reactive with oligosaccharides present in serum glycoproteins. Source-related differences in affinity between AFP glycoforms which bind to a lectin matrix will be investigated by monosaccharide hapten concentration gradient elution and sequential elutions with monosaccharide haptens of increasing lectin-binding affinity. Peptide:N-glycosidase-released AFP oligosaccharides will be analyzed by HPLC and their monosaccharide composition determined by GLC. Half-lives of AFP glycoforms present in postpartum maternal serum will be determined.
| Ajdukiewicz, A B; Kelleher, P C; Krawitt, E L et al. (1993) Alpha-fetoprotein glycosylation is abnormal in some hepatocellular carcinoma, including white patients with a normal alpha-fetoprotein concentration. Cancer Lett 74:43-50 |
