DNMT3B7 disrupts embryonic development and accelerates lymphomagenesis. Mus musculus

Cancer cells have an altered distribution of DNA methylation and express aberrant DNA methyltransferase 3B transcripts, which encode truncated proteins. To test if a truncated DNMT3B isoform disrupts DNA methylation in vivo, we constructed transgenic mice expressing DNMT3B7, a common truncated DNMT3B isoform in cancer cells. DNMT3B7 transgenic mice exhibit altered embryonic development, including lymphopenia, craniofacial abnormalities, and cardiac defects, similar to Dnmt3b-deficient animals, but rarely develop cancer. However, DNMT3B7 expression increases the frequency of mediastinal lymphomas in Eμ−myc animals. Eμ-myc/DNMT3B7 lymphomas have more chromosomal rearrangements, increased global methylation levels, and more locus-specific perturbations in DNA methylation patterns compared to Eμ-myc lymphomas. Our results demonstrate that a truncated DNMT3B protein can alter tumorigenesis, suggesting a similar role in human tumors. Overall design: Direct comparison of DNA methylation in lymphoma samples from Eu-Myc vs Eu-Myc/Dnmt3b7 mice.