| Abstract: |
Using β1,4-N-acetylgalactosaminyltransferase (EC 2.4.1.92) complementary DNA, the correlation of gene expression, enzyme activity, and expression of ganglioside antigens was analyzed in 20 human tumor cell lines. In many lines, GM2 and/or GD2 were the most complex structures examined. Northern blot analysis revealed 5.2- and 3.0-kilobase mRNAs in almost all cell lines expressing GD2 and/or GM2 Some melanoma lines, however, showed no bands although they expressed fairly high levels of GD2. These cell lines expressed very high levels of a2,8-sialyltransferase and the resulting product, GD3. Semiquantitative RT-PCR demonstrated that even cell lines with no bands in Northern blot contained 0.4-2.5% of mRNA level in the highest expressing cell line. These results indicate that GD2 expression on individual cell lines is regulated not only by the expression level of the JV-acetylgalactosaminyl transferase but also by the amount of its precursor structure (GD3) and a2,8-sialyltransferase present in the cells. 01,4-JV-acetylgalactosaminyltransferase activities and mRNA levels generally correlated quite closely. A few lines, however, showed lower enzyme activities than expected from their mRNA levels, indicating the possibility that the enzyme is being regulated by translational or post-translational modification such as phosphorylation and glycosylation as well as by transcriptional regulation. Depending on their patterns of ganglioside synthesis and expression, the lines examined were classified into 6 groups which were characteristic of different tumor cell types. © 1993, American Association for Cancer Research. All rights reserved. |
| Keywords: |
human cell; polymerase chain reaction; neoplasms; melanoma; gene expression; cancer cell culture; tumor cells, cultured; enzyme activity; antibodies, monoclonal; enzyme regulation; molecular sequence data; ganglioside gd2; messenger rna; rna, messenger; sialyltransferase; base sequence; ganglioside gd3; ganglioside gm2; complementary dna; northern blotting; gangliosides; ganglioside; glycosyltransferase; n-acetylgalactosaminyltransferases; n acetylgalactosamine; g(m3) ganglioside; blotting, southern; g(m2) ganglioside; human; priority journal; article; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; galactosyltransferases
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