Abstract 4466: Integrative study of dysregulated genes in translocated ALK-positive non-small cell lung cancer and personalized targeted therapy resistance.
Authors: Shi Ivy , Yin Lihong , Ma Patrick C. 
Published: August 2014

Abstract
Background: Recent studies revealed that ALK (anaplastic lymphoma kinase) 2p23 translocation, most commonly fused with echinoderm microtubule-associated protein-like 4 (EML4), is a novel driver oncogene in about 5% of non-small cell lung cancer (NSCLC). ALK 2p23 fusion (ALK+) can be diagnosed by dual color break-part ALK FISH assay to inform personalized targeted therapy using the ALK inhibitor crizotinib. However, the underlying mechanisms of ALK oncogenic signaling and more importantly ALK inhibitor crizotinib resistance are not well understood.
Materials and Methods: To understand the mechanism of oncogenic ALK signaling, an ALK+ NSCLC microarray dataset was retrieved from NCBI-GEO data repository (GSE31210) and analyzed using data-mining bioinformatics approaches. This dataset includes the gene expression profiles of 11 ALK+ NSCLC and 20 normal lung tissue samples. Statistical analysis was carried out to identify altered genes in ALK+ NSCLC and Ingenuity Pathway Analysis (IPA) software was deployed to uncover their network interactions. To study the resistance mechanism of the ALK+ H3122 human NSCLC cell line against the specific ALK inhibitor TAE684, real-time polymerase chain reaction (qRT-PCR), cell viability assay and immunoblotting were performed using standard techniques.
Results: We identified a set of 1,656 genes that were significantly altered in ALK+ NSCLC, consisting of 662 upregulated and 994 downregulated. The principal component analysis (PCA) based on the top 51 of these dysregulated genes evidently separated ALK+ and normal lung tissue samples, implicating that these genes could represent potential genomic signature of ALK+ NSCLC. The IPA analysis revealed 35 canonical pathways linked to ALK signaling, including beta-adrenergic and angiopoietin signaling pathways. The results of qRT-PCR, cell viability assay and immunoblotting showed that in translocated ALK+ H3122 human NSCLC cell line, HGF (hepatocyte growth factor) overexpression could activate ALK downstream signaling via activation of MET receptor kinase pathway, thus potentially bypassing the oncogenic ALK signaling under ALK inhibitor TAE684 treatment. Hence, alternative direct activation of ALK downstream signaling molecules via MET/HGF axis activation may potentially contribute to ALK inhibitor drug resistance.
Conclusion: Using bioinformatics data-mining, we have identified dysregulated genes and pathways in ALK+ NSCLC, many of which are novel biomarkers not previously reported. We also verified the relevance and potential key role of MET/HGF signaling axis in ALK inhibitor resistance. Taken together, our results highlighted the cross-talk between ALK and MET signaling in NSCLC and shed new insights into possible pitfalls of potential specific ALK targeting inhibitor drugs.
Citation Format: Ivy Shi, Lihong Yin, Patrick C. Ma. Integrative study of dysregulated genes in translocated ALK-positive non-small cell lung cancer and personalized targeted therapy resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4466. doi:10.1158/1538-7445.AM2013-4466