Dr. Shigeru Morikawa deceased after the submission.
Genetic and epigenetic inactivation of tax gene in adult T-cell leukemia cells
Article first published online: 9 JAN 2004
Copyright © 2004 Wiley-Liss, Inc.
International Journal of Cancer
Volume 109, Issue 4, pages 559–567, 20 April 2004
How to Cite
Takeda, S., Maeda, M., Morikawa, S., Taniguchi, Y., Yasunaga, J.-i., Nosaka, K., Tanaka, Y. and Matsuoka, M. (2004), Genetic and epigenetic inactivation of tax gene in adult T-cell leukemia cells. Int. J. Cancer, 109: 559–567. doi: 10.1002/ijc.20007
- Issue published online: 24 FEB 2004
- Article first published online: 9 JAN 2004
- Manuscript Accepted: 24 OCT 2003
- Manuscript Revised: 17 OCT 2003
- Manuscript Received: 24 APR 2003
- Ministry of Education, Science, Sports and Culture of Japan
- Welfide Medicinal Research Foundation
- Public Trust Haraguchi Memorial Cancer Research Fund
- DNA methylation;
To clarify the status of tax gene, we analyzed human T-cell leukemia virus type-I (HTLV-I) associated cell lines and fresh adult T-cell leukemia (ATL) cells. We compared 2 types of HTLV-I associated cell lines: one was derived from leukemic cells (leukemic cell line) and the other from nonleukemic cells (nonleukemic cell line). Although all nonleukemic cell lines expressed Tax, it could not be detected in 3 of 5 leukemic cell lines, in which nonsense mutation or deletion (60 bp) of tax genes, and DNA methylation in 5′-LTR were identified as the responsible changes. We found such genetic changes of the tax gene in 5 of 47 fresh ATL cases (11%). The tax gene transcripts could be detected in 14 of 41 fresh ATL cases (34%) by RT-PCR. In ATL cases with genetic changes that could not produce Tax protein, the tax gene was frequently transcribed, suggesting that such cells do not need the transcriptional silencing. Although DNA methylation of 5′-LTR was detected in the fresh ATL cases (19 of 28 cases; 68%), the complete methylation associated with transcriptional silencing was observed only in 4 cases. Since partial methylation could not silence the transcription, and the tax gene transcription was not detected in 27 of 41 cases (66%), the epigenetic change(s) other than DNA methylation is considered to play an important role in the silencing. © 2004 Wiley-Liss, Inc.