Mechanisms of suppression of cell growth by dual inhibition of ALK and MEK in ALK-positive non-small cell lung cancer

N Shrestha,P Dass,M Nimick,R J Rosengren,J C Ashton

doi:10.1038/s41598-019-55376-4

N Shrestha, P Dass + Show 3 more

Open Access

https://doi.org/10.1038/s41598-019-55376-4

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Journal: Scientific Reports	Publication Date: Dec 1, 2019
Citations: 19	License type: open-access

Affiliation: University of Otago

Abstract

Anaplastic lymphoma kinase (ALK) rearrangement, a key oncogenic driver in a small subset of non-small cell lung cancers, confers sensitivity to ALK tyrosine kinase inhibitors (TKIs). Crizotinib, a first generation ALK-TKI, has superiority to standard chemotherapy with longer progression-free survival and higher objective response rate. However, clinical benefit is limited by development of resistance, typically within a year of therapy. In this study the combined effect of crizotinib and the MEK inhibitor selumetinib was investigated in both crizotinib naïve (H3122) and crizotinib resistant (CR-H3122) ALK-positive lung cancer cells. Results showed that combination treatment potently inhibited the growth of both H3122 and CR-H3122 cells, resulting from increased apoptosis and decreased cell proliferation as a consequence of suppressed downstream RAS/MAPK signalling. The drug combination also elicited a greater than 3-fold increase in Bim, a mediator of apoptosis, and p27, a cyclin dependent kinase inhibitor compared to crizotinib alone. The results support the hypothesis that combining MEK inhibitors with ALK inhibitor can overcome ALK inhibitor resistance, and identifies Bim, PARP and CDK1 as druggable targets for possible triple drug therapy.

Highlights

Lung cancer is the leading cause of cancer mortality worldwide, accounting for approximately 1.59 million deaths annually[1]
The relative potency of crizotinib and selumetinib was initially examined in Anaplastic lymphoma kinase (ALK)-positive (H3122) and ALK-negative (A549) non-small cell lung cancer cells
In H3122 cells, 3 of the 6 drug combinations examined significantly reduced cell viability compared to both single drug treatments (p < 0.05) (Fig. 1B) and all drug combinations showed greater than Loewe additivity (Chou-Talalay Combination index < 1) (Fig. 1C)

Summary

Introduction

Lung cancer is the leading cause of cancer mortality worldwide, accounting for approximately 1.59 million deaths annually[1]. Mechanisms of resistance to crizotinib involve the alteration of the target gene itself either by mutation or amplification, and activation of bypass signalling pathways Some mediators in these signalling pathways are druggable targets and have been under investigation for combination drug treatment. ALK overexpression and constitutive activation is www.nature.com/scientificreports unique to ALK-positive NSCLC cells; with a highly specific first target established, the search for secondary targets is facilitated One strategy to this search is to investigate mediators of bypass signalling pathways as co-targets for combination with ALK inhibitors. These include receptor tyrosine kinases (RTKs) such as epidermal growth factor receptor (EGFR), insulin like growth factor receptor (IGFR), human epidermal growth factor receptor 2 (HER2) and cKIT, or mutation in EGFR or kirsten rat sarcoma (KRAS). We interrogated the pathways by which ALK/MEK inhibition suppressed cancer cell growth so as to identify more druggable targets, as the approach of Bozic et al requires a combination of three drugs or more to maximise suppression of cancer cell growth and prevention of drug resistance

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