Aurora A Kinase Inhibition Destabilizes PAX3-FOXO1 and MYCN and Synergizes with Navitoclax to Induce Rhabdomyosarcoma Cell Death

Abstract

◥The clinically aggressive alveolar rhabdomyosarcoma (RMS) 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 pharmacologic 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 top compound in a screen from 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.Significance: These findings show that Aurora kinase A and Bcl-2 family proteins are potential targets for FP-RMS.

Selective Inhibition of Aurora Kinase A by AK-01/LY3295668 Attenuates MCC Tumor Growth by Inducing MCC Cell Cycle Arrest and Apoptosis

“…AURKA has been shown to phosphorylate AKT and mTOR in promoting chemotherapy resistance [40]. This is unlikely the underlying mechanism leading to increased apoptosis in MCC cells as p-AKT and p-mTOR levels were unchanged upon AK-01 treatment.…”

“…Most Aurora kinase inhibitors developed are pan-Aurora or Aurora B/C inhibitors [33][34][35][36][37][38]. The most advanced Aurora inhibitor alisertib (MLN8237) has narrow Aurora A selectivity and has demonstrated anti-tumor activities when combined with various drugs in several human cancers [39][40][41]. Recently, a highly Aurora A-selective inhibitor, AK-01/LY3295668, developed by Eli Lilly (Eli Lilly, Indianapolis, IN, USA), has demonstrated over 1000-fold selectivity versus AURKB and has anti-tumor activities in a broad panel of cancer cell lines as well as in animal models [42].…”

Combination Therapy of Navitoclax with Chemotherapeutic Agents in Solid Tumors and Blood Cancer: A Review of Current Evidence

“…It was found that the application of a single-drug treatment against RMS increased the tendency of the rhabdomyosarcoma cells to be more drug resistant. Based on a study conducted by Ommer et al (2020), the activity of caspase 3/7 in fusion-positive (F.P.) RMS cell lines and patient-derived xenograft (PDX) increased significantly following the loss of the PAX3-FOXO1 protein induced by alisertib, an aurora kinase A (AURKA) inhibitor.…”

A combinatorial drug screen in PDX-derived primary rhabdomyosarcoma cells identifies the NOXA - BCL-XL/MCL-1 balance as target for re-sensitization to first-line therapy in recurrent tumors

“…While NOXA knock-outs did not completely rescue from apoptosis, suggesting that to some extent also other pro-apoptotic players are involved, we did not find any cell death alteration in BIM knock-out cells treated with either ABT-263 alone or with chemotherapy (data not shown), albeit BIM has been proposed as a key determinant of the sensitivity to ABT-263 in a large collection of cancer cell lines [28] . NOXA has already been recognized as a major stress sensor in both FP-RMS and FN-RMS, initiating mitochondrial apoptosis downstream of several types of treatments [ [12] , [13] , [14] , [15] , [16] , 29 ]. This suggests that NOXA is the main BH3-only stress sensor in most RMS cells.…”