Context Dependent Roles of MDMX (MDM4) and MDM2 in Breast Cancer Proliferation and Circulating Tumor Cells

Introduction Many human breast cancersoverexpress the E3 ubiquitin ligase MDM2and its homolog MDMX. Expression of MDM2and MDMXoccurs in estrogen receptorα-positive (ERα+) breast cancerand triple-negative breast cancer(TNBC). There are p53-independent influences of MDM2and MDMX, and 80% of TNBC express mutant p53 (mtp53). MDM2drives TNBC circulating tumor cells(CTCs) in mice, but the context-dependent influences of MDM2and MDMXon different subtypes of breast cancersexpressing mtp53 have not been determined.