Project description:MYC is a potent oncogene associated with aggressive disease in many distinct tumor types. Transforming members of the MYC family (MYC, MYCL1, MYCN) encode transcription factors containing six highly conserved regions, termed MYC homology Boxes (MBs). Here, we conduct proteomic profiling of the MB interactomes, demonstrating that half of MYC interactors require one or more MBs for binding. Comprehensive phenotypic analyses revealed that two MBs are universally required for transformation. MBII interaction with acetyltransferase-containing complexes results in histone hyperacetylation and is essential for MYC-dependent tumor initiation. By contrast, MB0 interacts with transcription elongation factors through direct binding to the general transcription factor TFIIF, and deletion of MB0 severely inhibits tumor growth but is dispensable for tumor initiation. Notably, the full transforming activity of MYC can be restored upon co-expression of MB0 and MBII deletion mutants, indicating that these two regions confer unique biological functions, each required for oncogenic MYC activity.
Project description:MYC is a potent oncogene associated with aggressive disease in many distinct tumor types. Transforming members of the MYC family (MYC, MYCL1, MYCN) encode transcription factors containing six highly conserved regions, termed MYC homology Boxes (MBs). Here, we conduct proteomic profiling of the MB interactomes, demonstrating that half of MYC interactors require one or more MBs for binding. Comprehensive phenotypic analyses revealed that two MBs are universally required for transformation. MBII interaction with acetyltransferase-containing complexes results in histone hyperacetylation and is essential for MYC-dependent tumor initiation. By contrast, MB0 interacts with transcription elongation factors through direct binding to the general transcription factor TFIIF, and deletion of MB0 severely inhibits tumor growth but is dispensable for tumor initiation. Notably, the full transforming activity of MYC can be restored upon co-expression of MB0 and MBII deletion mutants, indicating that these two regions confer unique biological functions, each required for oncogenic MYC activity.
Project description:The fibroblast growth factor pathway is known to cooperate with the highly oncogenic Wnt/ï¢-catenin pathway in mouse models of breast cancer. To investigate the mechanisms involved in this cooperativity, we utilized MMTV-driven transgenic mouse lines expressing a drug-inducible model for FGF Receptor signaling (iFGFR) crossed with the previously characterized MMTV-Wnt-1 mouse model. In these bigenic mice, both iFGFR1 and iFGFR2 activation resulted in a dramatic enhancement of mammary tumorigenesis. Tumor microarray analysis identified no transcriptional enhancement of Wnt/ï¢-catenin targets, however, identified a protein translational gene signature that also correlated with elevated FGFR1 and FGFR2 expression in several human breast cancer data sets. Additionally, iFGFR1 activation resulted in enhanced polysome recruitment and a marked increase in protein expression of several different Wnt/ï¢-catenin target oncogenes. Rapid FGFR-induced ERK activation and phosphorylation of key translation regulators was observed both in vivo in the transgenic mouse model, and in human breast cancer cell lines treated with exogenous FGF. These studies suggest that translational regulation is a key rate-limiting step required for oncogenic cooperativity between the Wnt and FGF pathways. reference X sample