Abstract |
Pim kinases are found to be highly expressed in leukemia, lymphoma, prostate and pancreatic cancer. Bitransgenic mice overexpressing either Pim-1 or Pim-2 and c-Myc succumb to pre-B-cell lymphoma at a strikingly accelerated speed. Despite that Pim-1/Pim-2 has long been recognized as a strong synergistic partner with c-Myc in tumorigenesis, the mechanism underlying the synergism is still not well understood. Overexpression of Pim-1/Pim-2 kinase dramatically stabilizes c-Myc in vivo, and the stabilization is partially mediated by phosphorylation of c-Myc by Pim kinase on a novel site, Ser329. We provide evidence that Pim-2 is more efficient in directly phosphorylating c-Myc Ser329 to stabilize c-Myc. In contrast, we find that Pim-1 is more effective in mediating a decrease in c-Myc Thr58 phosphorylation and an increase in c-Myc Ser62 phosphorylation than in phosphorylating Ser329. In either case, through stabilizing c-Myc, Pim-1/Pim-2 kinases enhance the transcriptional activity of c-Myc. Also knocking down either Pim-1 or Pim-2 dramatically decreases the endogenous levels of c-Myc and thus, its transcriptional activity. Finally, coexpression of the Pim kinases and c-Myc enhances the transforming activity of c-Myc as does the phosphomimic mutant of c-Myc on Ser329. We conclude that these findings appear to explain at least in part the mechanism underlying the synergism between the Pim kinases and c-Myc in tumorigenesis.
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Authors | Y Zhang, Z Wang, X Li, N S Magnuson |
Journal | Oncogene
(Oncogene)
Vol. 27
Issue 35
Pg. 4809-19
(Aug 14 2008)
ISSN: 1476-5594 [Electronic] England |
PMID | 18438430
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
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Chemical References |
- Proto-Oncogene Proteins c-pim-1
- proto-oncogene proteins pim
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Topics |
- Animals
- Genes, myc
- Hydrolysis
- Mice
- Mice, Transgenic
- Phosphorylation
- Proto-Oncogene Proteins c-pim-1
(metabolism)
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