Poster Presentation 35th Lorne Cancer Conference 2023

Characterising the role of a p53 regulated Huwe1 enhancer in Eμ-Myc lymphomagenesis (#171)

Wei Jin 1 2 , Yexuan Deng 1 2 , Andrew Kueh 1 2 , Lin Tai 1 2 , Marco Herold 1 2
  1. Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
  2. WEHI, Carlton, VIC, Australia

The deregulation of c-Myc accounts for the development of 70% of human cancers including malignant B cell lymphomas. The Eμ-Myc transgenic mouse model is designed to mimic Burkitt’s lymphoma (an aggressive B cell lymphoma subtype) by translocating the c-Myc gene so that it is under the control of the immunoglobulin heavy (IgH) chain enhancer Eμ, which causes c-Myc overexpression in early B lymphoid cells and eventually tumour formation. It has been shown that the loss of p53 can accelerate c-Myc-driven tumorigenesis in mice. To further investigate the mechanism of p53-dependent tumour suppression in Eμ-Myc driven lymphomagenesis, a p53-bound enhancer/promoter sgRNA library screen using CRISPR/Cas9 was conducted in vivo. This screen led to the discovery of a p53-bound enhancer potentially regulating the Huwe1 gene. Huwe1 is a HECT-domain containing E3 ubiquitin ligase that also possesses a UBA domain, a WWE domain, and a BH3 domain, which enables Huwe1 to ubiquitinate numerous proteins such as MCL-1 or c-MYC. The role of Huwe1 enhancer in Eμ-Myc lymphomagenesis will be characterised using CRISPR technologies. We will use traditional CRISPR/Cas9 technology, but will extend our genome editing effort to Cas12a, as this will allow us to simultaneously edit multiple genes. Initial experiments suggest that knockout of the HUWE1 enhancer accelerates Eμ-Myc lymphomagenesis. In vitro results indicate that p53 does indeed bind and regulate HUWE1 by this newly identified enhancer element. In summary, we have potentially identified a novel tumour suppressive function of p53, which we will interrogate in further in vivo studies in the future.