Loss of Fbxw7 triggers mammary tumorigenesis associated with E2F/c-Myc activation and Trp53 mutation.

Loss of Fbxw7 triggers mammary tumorigenesis associated with E2F/c-Myc activation and Trp53 mutation. Neoplasia. 2020 Nov;22(11):644-658 Authors: Meyer AE, Furumo Q, Stelloh C, Minella AC, Rao S Abstract Fbw7 is a tumor suppressor that regulates the degradation of oncogenic substrates such as c-Jun, c-Myc, Notch1 intracellular domain (ICD), and cyclin E by functioning as the substrate recognition protein in the Skp1-Cullin-F-box (SCF) ubiquitin ligase complex. Consequently, low expression or loss of FBXW7 in breast cancer has been hypothesized to result in the accumulation of oncogenic transcription factors that are master regulators of proliferation, apoptosis, and ultimately transformation. Despite this, the direct effect of Fbw7 loss on mammary gland morphology and tumorigenesis has not been examined. Here, we demonstrate that conditional deletion of Fbxw7 in murine mammary tissue initiates breast tumor development and also results in lactation and involution defects. Further, while Fbxw7 loss results in the overexpression of Notch1-ICD, c-Jun, cyclin E, and c-Myc, the downstream transcription factor pathways associated with c-Myc and cyclin E are the most dysregulated, including at the single-cell level. These pathways are dysregulated early after Fbxw7 loss, and their sustained loss results in tumorigenesis and reinforced c-Myc and cyclin E-E2F pathway disruption. We also find that loss of Fbxw7 is linked to the acquisition of T...
Source: Neoplasia - Category: Cancer & Oncology Authors: Tags: Neoplasia Source Type: research