Small Molecule Kinase Inhibitor Screen Identifies Polo-Like Kinase 1 as a Target for Neuroblastoma Tumor-Initiating Cells

Natalie Grinshtein,Natalie Grinshtein,Natalie Grinshtein,Natalie Grinshtein,Natalie Grinshtein,Rima Al-Awar,David R Kaplan,Alessandro Datti,Alessandro Datti,Alessandro Datti,Alessandro Datti,Alessandro Datti,Rima Al-Awar,Meredith S Irwin,Jeffrey L Wrana,Jeffrey L Wrana,Jeffrey L Wrana,Jeffrey L Wrana,Jeffrey L Wrana,David R Kaplan,Mayumi Fujitani,Mayumi Fujitani,Mayumi Fujitani,Meredith S Irwin,Mayumi Fujitani,David R Kaplan,Meredith S Irwin,Rima Al-Awar,Rima Al-Awar,Meredith S Irwin,David R Kaplan,David Uehling,David Uehling,David Uehling,David Uehling,David Uehling,Michael Prakesch,Meredith S Irwin,Methvin Isaac,Methvin Isaac,Methvin Isaac,Methvin Isaac,Methvin Isaac,Rima Al-Awar,David R Kaplan,Mayumi Fujitani

doi:10.1158/0008-5472.can-10-2484

Abstract

Neuroblastoma (NB) is an often fatal pediatric tumor of neural crest origin. We previously isolated NB tumor-initiating cells (NB TIC) from bone marrow metastases that resemble cancer stem cells and form metastatic NB in immunodeficient animals with as few as ten cells. To identify signaling pathways important for the survival and self-renewal of NB TICs and potential therapeutic targets, we screened a small molecule library of 143 protein kinase inhibitors, including 33 in clinical trials. Cytostatic or cytotoxic drugs were identified that targeted PI3K (phosphoinositide 3-kinase)/Akt, PKC (protein kinase C), Aurora, ErbB2, Trk, and Polo-like kinase 1 (PLK1). Treatment with PLK1 siRNA or low nanomolar concentrations of BI 2536 or BI 6727, PLK1 inhibitors in clinical trials for adult malignancies, were cytotoxic to TICs whereas only micromolar concentrations of the inhibitors were cytotoxic for normal pediatric neural stem cells. Furthermore, BI 2536 significantly inhibited TIC tumor growth in a therapeutic xenograft model, both as a single agent and in combination with irinotecan, an active agent for relapsed NB. Our findings identify candidate kinases that regulate TIC growth and survival and suggest that PLK1 inhibitors are an attractive candidate therapy for metastatic NB.

Highlights

Neuroblastoma (NB) is the most common and deadly extracranial solid tumor in children [1, 2]
To identify signaling pathways required for NB tumorinitiating cells (NB tumor-initiating cells" (TIC)) survival and proliferation, we screened low-passage TIC lines from bone marrow metastases from 3 high-risk NB patients (NB12, NB88R2, and NB122R) with a collection of 143 kinase inhibitors (Fig. 1A)
We screened a kinase inhibitor library to identify candidate protein kinases that play a role in NB TIC survival and self-renewal

Summary

Introduction

Neuroblastoma (NB) is the most common and deadly extracranial solid tumor in children [1, 2]. Despite intensive treatment regimens, comprising surgery, chemotherapy, and irradiation, high-risk NB patients with relapse in the bone marrow have a long-term survival rate of less than 10% [1, 2]. Patients who respond to chemotherapy are at risk for developing long-term complications such as hearing loss, cardiac dysfunction, and infertility. BI 2536 suppresses NB tumor growth in a therapeutic xenograft model as a single agent and in combination with irinotecan. We evaluated the efficacy of BI 2536 treatment on NB tumors in vivo. BI 2536 or vehicle was administered intravenously to NOD/SCID mice that had developed NB88R2 xenograft tumors of 50- to 100-mm volume. Vehicle BI 2536, 12.5 mg/kg Irinotecan, 10 mg/kg BI 2536 (12.5 mg/kg) + Irinotecan (10 mg/kg)

Methods

Results

Conclusion