We exploited the fact that leukemic cells utilize significantly higher levels of S-adenosylmethionine (SAMe) than normal lymphocytes and developed tools that selectively diminished their survival under physiologic conditions. Using RNA interference gene silencing technology, we modulated the kinetics of methionine adenosyltransferase-II (MAT-II), which catalyzes SAMe synthesis from ATP and L-Met. Specifically, we silenced the expression of the regulatory MAT-IIβ subunit in Jurkat cells and accordingly shifted the K m L-Met of the enzyme 10-15-fold above the physiologic levels of L-Met, thereby reducing enzyme activity and SAMe pools, inducing excessive apoptosis and diminishing leukemic cell growth in vitro and in vivo. These effects were reversed at unphysiologically high L-Met (>50 μM), indicating that diminished leukemic cell growth at physiologic L-Met levels was a direct result of the increase in MAT-II Km L-Met due to MAT-IIβ ablation and the consequent reduction in SAMe synthesis. In our NOD/Scid IL-2Rγnull humanized mouse model of leukemia, control shRNA-transduced Jurkat cells exhibited heightened engraftment, whereas cells lacking MAT-IIβ failed to engraft for up to 5 weeks post-transplant. These stark differences in malignant cell survival, effected by MAT-IIβ ablation, suggest that it may be possible to use this approach to disadvantage leukemic cell survival in vivo with little to no harm to normal cells.
CITATION STYLE
Attia, R. R., Gardner, L. A., Mahrous, E., Taxman, D. J., LeGros, L., Rowe, S., … Kotb, M. (2008). Selective targeting of leukemic cell growth in vivo and in vitro using a gene silencing approach to diminish S-adenosylmethionine synthesis. Journal of Biological Chemistry, 283(45), 30788–30795. https://doi.org/10.1074/jbc.M804159200
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