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Transfer RNA Methylases of Normal Cells, Virus-transformed Cells, and Tumors Derived from Transformed Cells¹

Section on Cellular Control Mechanisms, Human Tumor Cell Biology Branch, National Cancer Institute, NIH [s. F., R. C. G.], and Special Cancer Material Laboratory, Bionetics Research Laboratories [R. C. T.], Bethesda, Maryland 20014

Transfer RNA methylases (rate and capacity) were studied in normal cells and tissues, in RNA and DNA oncogenic virus-transformed cells, and in tumors derived from the transformed cells. The DNA oncogenic virus-transformed cells (SV40 and polyoma) contained greater tRNA methylase capacities than their nontransformed normal cells. In contrast, no difference was observed (capacity or rate) between normal cells and the same cells transformed by RNA oncogenic virus (murine sarcoma virus). However, tumors derived from these murine sarcoma virus-transformed cells, as well as normal fetal tissues, show 2- to 3-fold greater activities compared to various normal adult tissues. The results are discussed in terms of a correlation of tRNA methylase derepression with the state of differentiation of the cell.

¹ This work was undertaken during the tenure of a Research Training Fellowship awarded by the International Agency for Research on Cancer, WHO, and of a fellowship from the Alexander and Margaret Stewart Trust (S. F.). This investigation was partly supported by NIH chemotherapy Contract NIH-70-2050 and NIH Contract 71-2025 from the Special Virus Cancer Program of the National Cancer Institute.

² To whom requests for reprints should be addressed, at National Cancer Institute, NIH, Bethesda, Md. 20014.

Received 9/15/70. Accepted 12/ 3/70.