Significance of S-adenosylmethionine pools in the hypomethylation of ribosomal RNA during the propagation of tissue culture cells and oncogenesis

The 5.8S rRNA of normal tissues contains a partially 2'-O-methylated uridylic acid residue which is methylated in the cytoplasm and undermethylated in rapidly growing neoplastic tissues (R. N. Nazar, T. O. Sitz, and K. D. Somers, J. Mol. Biol., 142: 117-121, 1980). This difference in methylatio...

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Published inCancer research (Chicago, Ill.) Vol. 43; no. 12; pp. 5681 - 5686
Main Authors SITZ, T. O, GODBURN, K. E, SOMERS, K. D, NAZAR, R. N
Format Journal Article
LanguageEnglish
Published Philadelphia, PA American Association for Cancer Research 01.12.1983
Subjects
Animals
Biological and medical sciences
Carcinogenesis, carcinogens and anticarcinogens
Cell Cycle
Cell Line
Cell Transformation, Neoplastic
Child
Fibroblasts - physiology
General aspects
HeLa Cells - physiology
Humans
Kidney - physiology
Kinetics
Liver - physiology
Liver Regeneration
Male
Medical sciences
Methylation
Osteosarcoma - physiopathology
Rats
Rats, Inbred Strains
RNA, Ribosomal - genetics
S-Adenosylhomocysteine - metabolism
S-Adenosylmethionine - metabolism
Tumors
Metabolism
Carcinogenesis
Aminoacid
Tumoral tissue
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Summary:The 5.8S rRNA of normal tissues contains a partially 2'-O-methylated uridylic acid residue which is methylated in the cytoplasm and undermethylated in rapidly growing neoplastic tissues (R. N. Nazar, T. O. Sitz, and K. D. Somers, J. Mol. Biol., 142: 117-121, 1980). This difference in methylation was further characterized by examining the effect of cell age or cell culture passage number on the level of methylation of 5.8S RNAs from normal and malignant cell lines and simultaneous changes in intracellular pools of S-adenosylmethionine and S-adenosylhomocysteine. The results indicate that the level of methylation decreases continuously with cell culture passage number as the cells become aneuploid, transformed, or tumorigenic, but there is no direct correlation with the intracellular pools of S-adenosylmethionine or S-adenosylhomocysteine. In contrast, there is a dramatic but inverse increase in the S-adenosylmethionine:S-adenosylhomocysteine ratio which correlates with the decreasing levels of 2'-O-methylation. The significance of these changes in substrate levels to the hypomethylation of 5.8S and other RNAs during oncogenesis is discussed.
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ISSN:0008-5472
1538-7445