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The CRL7FBXW8 Complex Controls the Mammary Stem Cell Compartment Through Regulation of NUMB Levels

Sabbioni, S.; Filippone, M. G.; Amadori, L.; Confalonieri, S.; Bonfanti, R.; Capoano, S.; Colaluca, I. N.; Freddi, S.; Bertalot, G.; Faga, G.; Zagarri, E.; Varasi, M.; Gunby, R. H.; Mercurio, C.; Pece, S.; Di Fiore, P. P.; Tosoni, D.

2025-03-03 cancer biology
10.1101/2025.02.27.640530 bioRxiv
Show abstract

NUMB is a tumor suppressor gene that functions by inhibiting the action of the NOTCH proto-oncogene and enhancing the levels and activity of the tumor suppressor protein p53. In breast cancer (BC), NUMB loss-of-function (LOF), mediated by various molecular mechanisms, is a frequent and causal event. Herein, we establish that loss of NUMB protein, resulting from protein hyper-degradation, is the prevalent mechanism of NUMB LOF in BC. Through a RNAi-based screening, we identified the CRL7FBXW8 complex as the E3 ligase complex responsible for NUMB hyper-degradation in BC. Genetic and pharmacological inhibition of CRL7FBXW8 rescued the transformation-related phenotypes induced by NUMB LOF in BC cell lines and in patient-derived xenografts. These effects were directly dependent on the restoration of NUMB protein levels. Thus, enhanced CRL7FBXW8 activity, through its interference with the tumor suppressor activity of NUMB, is a causal alteration in BC, suggesting it as a potential therapeutic target for precision medicine.

Published in Advanced Science (predicted rank #18) · training set

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