Aurora A kinase inhibition destabilizes PAX3-FOXO1 and MYCN and synergizes with Navitoclax to induce Rhabdomyosarcoma cell death

December 30, 2019

Sigma- Aldrich). Drugs (Supplemental Table 1) were purchased from Selleckchem and added to the cells using the HP D300 Digital Dispenser (Tecan). 24h after seeding cells, medium was changed to 19 Îźl culture medium

The clinically aggressive alveolar rhabdomyosarcoma subtype is characterized by expression of the oncogenic fusion protein PAX3-FOXO1, which is critical for tumorigenesis and cell survival. Here we studied the mechanism of cell death induced by loss of PAX3-FOXO1 expression and identified a novel pharmacological combination therapy that interferes with PAX3-FOXO1 biology at different levels. Depletion of PAX3-FOXO1 in fusion positive (FP)-RMS cells induced intrinsic apoptosis in a NOXA-dependent manner. This was pharmacologically mimicked by the BH3 mimetic navitoclax, identified as a top compound in a screen of 208 targeted compounds. In a parallel approach, and to identify drugs that alter the stability of PAX3-FOXO1 protein, the same drug library was screened and fusion protein levels were directly measured as a read-out. This revealed that inhibition of Aurora kinase A most efficiently negatively affected PAX3-FOXO1 protein levels. Interestingly, this occurred through a novel specific phosphorylation event in and binding to the fusion protein. Aurora kinase A inhibition also destabilized MYCN, which is both a functionally important oncogene and transcriptional target of PAX3-FOXO1. Combined treatment with an Aurora kinase A inhibitor and navitoclax in FP-RMS cell lines and patient-derived xenografts synergistically induced cell death and significantly slowed tumor growth. These studies identify a novel functional interaction of Aurora kinase A with both PAX3-FOXO1 and its effector MYCN, and reveal new opportunities for targeted combination treatment of FP-RMS. Copyright Š2019, American Association for Cancer Research.

Ommer, J; Selfe, JL; Wachtel, M; O'Brien, EM; Laubscher, D; Roemmele, M; Kasper, S; Delattre, O; Surdez, D; Petts, G; Kelsey, A; Shipley, J; Schäfer, BW;

Journal: Cancer Res.

Original article (31888889)