Cell line specific abnormalities in expression of PNA, SBA and L-PHA binding sites by carcinogen induced rat...

Bladder tumor cell lines derived from male F344 rats treated with N-buthyl N-(4-hydroxybuthyl) nitrosamine (BBN) or N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) have been established in vitro and characterized with respect to histology, karyotype, myc and c-Ha-ras oncogene expression or mutation, anchorage-independent growth and tumorigenicity in nude mice. This unique model system comprising 13 cell populations was employed to study common events during development of carcinogen-induced urothelial neoplasia. Differential expression of malignant phenotypes by these cell lines prompted us to examine their expression of carbohydrate structures binding peanut agglutinin (PNA), soy bean agglutinin (SBA) or leukoagglutinin (L-PHA), which are known indicators of tumor progression in rodents and humans. In the present study we analyzed the patterns of glycoproteins reactive with PNA and L-PHA by Western blotting. We also estimated quantitative differences in lectin binding to surfaces of normal rat urothelium and tumor cell lines by flow cytometry. The patterns of PNA or L-PHA reactive glycoproteins expressed by tumor cells were different from that of normal urothelium in culture. They were also different amongst the tumor cells. A unique non-sialylated, PNA binding glycoprotein (117 kD) was seen in the case of the highly tumorigenic F5 cell line and absent in normal urothelium as well as in other tumor cell lines. Normal cells did not express glycoprotein 60 kD binding PNA (only after desialylation), which was found in lysates of some but not all transformed cell lines. A very high molecular weight (much greater than 200), perhaps mucin-like sialoglycoprotein was found in normal urothelium but not in most of the tumor cell lines. Four major L-PHA reactive bands (greater than 200, 190, 100, 80 kD approximately) were found in normal urothelium. Some of those bands were overexpressed or missing in materials isolated from different tumor cell populations. Total cell surface binding of SBA and PNA by different tumor cell lines was very heterogenous (167-2% that of normal urothelium). No simple correlation between expression of the lectin binding glycoconjugates by urothelial carcinoma cells and other known functional, phenotypic or genetic alterations was found. We were also unable to demonstrate carcinogen-specific changes in expression of lectin binding to these tumor cell lines. Thus we conclude that lectin binding patterns are cell line specific. This may reflect distinct pathways of progression of individual cell lines. The potential sources of phenotypic variability between the cell lines were discussed.