Deregulation of the endogenous C/EBPM-NM-2 LIP isoform predisposes to tumorigenesis
Ontology highlight
ABSTRACT: Two long and one truncated isoforms (termed LAP*, LAP, and LIP, respectively) of the transcription factor CCAAT enhancer binding protein beta (C/EBPM-NM-2) are expressed from a single intronless Cebpb gene by alternative translation initiation. Isoform expression is sensitive to mammalian target of rapamycin (mTOR)-mediated activation of the translation initiation machinery and relayed through an upstream open reading frame (uORF) on the C/EBPM-NM-2 mRNA. The truncated C/EBPM-NM-2 LIP, initiated by high mTOR activity, has been implied in neoplasia, but it was never shown whether endogenous C/EBPM-NM-2 LIP may function as an oncogene. In this study, we examined spontaneous tumor formation in C/EBPM-NM-2 knockin mice that constitutively express only the C/EBPM-NM-2 LIP isoform from its own locus. Our data show that deregulated C/EBPM-NM-2 LIP predisposes to oncogenesis in many tissues. Gene expression profiling suggests that C/EBPM-NM-2 LIP supports a protumorigenic microenvironment, resistance to apoptosis, and alteration of cytokine/chemokine expression. The results imply that enhanced translation reinitiation of C/ EBPM-NM-2 LIP promotes tumorigenesis. Accordingly, pharmacological restriction of mTOR function might be a therapeutic option in tumorigenesis that involves enhanced expression of the truncated C/EBPM-NM-2 LIP isoform. A cohort of C/EBPb LIP heterozygous (+/L) and wild type (+/+) mice were kept over 25 months and animals showing palpable lymphoma were sacrificed. The lymphoma developed spontaneously. For each genotype, 5 lymphoma were used for RNA preparation and gene expression profiling analysis.
ORGANISM(S): Mus musculus
SUBMITTER: Valerie Begay
PROVIDER: E-GEOD-53770 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
ACCESS DATA