Oncogene addiction and radiation oncology: effect of radiotherapy with photons and carbon ions in ALK-EML4 translocated NSCLC

Ying Dai,Amir Abdollahi,Stefan Rieken,Janina Hanne,Quanxiang Wei,Cheng Zhou,Kenneth E Lipson,Jürgen Debus,Klaus Herfarth,Christian Schwager

doi:10.1186/s13014-017-0947-0

Abstract

BackgroundPatients with Echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) positive lung cancer are sensitive to ALK-kinase inhibitors. TAE684 is a potent second generation ALK inhibitor that overcomes Crizotinib resistance. Radiotherapy is an integral therapeutic component of locally advanced lung cancer. Therefore, we sought to investigate the effects of combined radiotherapy and ALK-inhibition via TAE684 in ALK-positive vs. wild type lung cancer cells.MethodsHuman non-small cell lung cancer (NSCLC) cell lines harboring wild-type ALK (A549), EML4-ALK translocation (H3122) and murine Lewis Lung Cancer (LLC) cells were investigated. Cells were irradiated with 1–4 Gy X-Rays (320 keV) and carbon ions (Spread-out Bragg Peak, SOBP (245.4–257.0 MeV/u)) at Heidelberg Ion Therapy center. TAE684 was administered at the dose range 0–100 nM. Clonogenic survival, proliferation and apoptosis via caspase 3/7 expression level were assessed in all three cell lines using time-lapse live microscopy.ResultsTAE684 inhibited the proliferation of H3122 cells in a dose-dependent manner with a half maximal inhibitory concentration (IC50) of ~ 8.2 nM. However, A549 and LLC cells were relatively resistant to TAE684 and IC50 was not reached at concentrations tested (up to 100 nM) in proliferation assay. The antiproliferative effect of TAE684 was augmented by radiotherapy in H3122 cells. TAE684 significantly sensitized H3122 cells to particle therapy with carbon ions (sensitizer enhancement ratio ~1.61, p < 0.05). Caspase 3/7 activity was evidently enhanced after combination therapy in H3122 cells.ConclusionsThis is the first report demonstrating synergistic effects of combined TAE684 and radiotherapy in EML4-ALK positive lung cancer cells. In addition to conventional photon radiotherapy, ALK-inhibition also enhanced the effects of particle irradiation using carbon ions. Our data indicate beneficial effects of combined ALK-inhibition and radiotherapy in treatment of this distinct subpopulation of NSCLC that warrant further evaluation.

Highlights

Patients with Echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) positive lung cancer are sensitive to ALK-kinase inhibitors
Cells and cell culture Lewis Lung Cancer (LLC) cells were purchased from ATCC, Manassas, USA; adenocarcinomic human alveolar basal epithelial (A549) cells were obtained from Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ) and the human non-small cell lung cancer (NSCLC) cell line H3122 was provided by Frederick National Laboratory for Cancer Research, Maryland, USA
Antiproliferative effects of TAE684 in NSCLC To assess the effects of TAE684 on cell proliferation, EML4-ALK fusion positive H3122 cells as well as A549 and LLC were treated with TAE684 (0–100 nM) and relative proliferation was determined 72 h post treatment using the Cyquant assay

Summary

Introduction

Patients with Echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) positive lung cancer are sensitive to ALK-kinase inhibitors. The EML4-ALK fusion protein leads to an aberrant activation of the ALK tyrosine kinase and its related downstream signaling [13]. Soda et al have shown that cells overexpressing EML4-ALK are able to generate subcutaneous or lung orthotopic tumors in a nude mouse model [9, 17]. Another chromosomal translocation between the nucleophosmin (NPM) gene on chromosome 5q35 and ALK gene on 2p23 is expressed in 60%–70% of anaplastic large cell lymphoma (ALCLs) [13, 18, 19]

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