X-ray-induced lymphomagenesis in Eμ-pim-1 transgenic mice: An investigation of the co-operating molecular events

C. W. Van Der Houven Van Oordt, T. G. Schouten, J. H.J.M. Van Krieken, J. H.J. Van Dierendonck, A. J. Van Der Eb, M. L. Breuer

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22 Citations (Scopus)


Transgenic mice overexpressing the pim-1 oncogene in their lymphoid compartment display a low incidence of spontaneous T-cell lymphomas, but are highly susceptible to point mutation-inducing genotoxic carcinogens. We show here that total body X-irradiation, which causes mainly chromosomal deletions, rearrangements and amplifications, significantly enhances lymphoma development in Eμ-pim-1 transgenic mice. The X-ray-induced Eμ-pim-1 and nontransgenic lymphomas have a comparable high cell turnover as shown by a relatively high S-phase fraction and a high apoptotic activity. Consistent with previous observations, in 75% of all lymphomas c-myc mRNA levels are 5- to 20-fold higher than in control, non-lymphomatous spleen/thymus. The expression of other oncogenes, which have previously found to be activated in combination with pim-1 in lymphomagenesis, such as gfi-1/pal-1, frat-1 and tiam-1, and also of the mdm-2 and mdm-x oncogenes, appeared not to be affected. Deletions and/or rearrangements of the pl6(INK4A) and p15(INK4B) tumor suppressor genes were seldom observed (in three out of 92 X-ray-induced lymphomas). Strikingly, in addition to the high mRNA levels of the pim-1 transgene, the levels of the endogenous pim-1 transcripts were elevated significantly in 16% of the X-ray-induced Eμ-Pim-1 lymphomas compared with control spleen, even surpassing the level of the pim-1 transgene mRNA by 3- to 5-fold. In combination with previous results, which showed that the lymphoma incidence increased concordantly with higher levels of pim-1, this supports the notion that pim-1 can contribute to lymphomagenesis in a dose-dependent manner.

Original languageEnglish
Pages (from-to)847-853
Number of pages7
Issue number5
Publication statusPublished - May 1998
Externally publishedYes

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