Abstract LB-309: EML4-ALK signaling is required for the maintenance of neoplastic phenotype of non-small cell lung cancer cells: Novel strategy for lung cancer-tailored therapies
Authors: Voena Claudia , Panizza Elena , D'Amico Lucia , Ambrogio Chiara , Cinzia Martinengo , Boccalatte Francesco , Riera Ludovica , Bonello Lisa , Pulito Roberta , Hamm Jorg , Cheng Mangeng , Ruggeri Bruce , Gu Ting-Lei , Polakiewicz Roberto D. , Medico Enzo , Chiarle Roberto , Inghirami Giorgio 
Published: February 2011

Abstract
Lung cancer is the most common cancer in the world, and is lethal in 90% of the cases. In non-small cell lung cancer (NSCLC), deregulated receptor tyrosine kinases (RTKs) stand out among the causal dominant oncogenes. Consequently, the genomic and/or pharmacological ablation of RTK signaling has emerged as a novel tailored therapeutic strategy. Nevertheless, this approach has serious constrains, probably due to the frequent co-activation of multiple RTKs in a considerable subsets of solid tumors. It has become also evident that during TK inhibitor-based regimens, RTK switching and/or the selection of resistant clones can frequently occur representing a serious and problematic drawback. In a subset of NSCLC, the Anaplastic Lymphoma Kinase (ALK) gene has been described to be translocated and fused to EML4. This determines the ALK constitutive dimerization and autophosphorylation leading to cellular transformation. Here, we investigated the ALK oncogenic addiction of human NSCLC and studied the putative co-operative role of other kinases. We first demonstrated that the ectopic expression of EML4-ALK in ALK positive NSCLC cell lines (H2228 and H3122) resulted in the activation of multiple signaling pathways, in manner similar to that described for other known ALK fusions. Although EML4-ALK can induce transformation in lung in vitro and in vivo, ALK inhibition via shRNA or small molecule inhibitors (CEPs, Cephalon) induced only the apoptosis of H3122 cells, whereas in H2228 it caused cell growth arrest. Moreover, the treatment with ALK inhibitors led to tumor regression, but not tumor eradication, in vivo. Based on Phosphoproteomic analyses we demonstrated that the phosphorylation status of several tyrosine kinases (such as, EGFR, Met, FGFR, Jak1 or IGFR) was affected by the ALK inhibition only in H2228 cell line, but not in H3122. Notably, the combined treatment with anti-ALK (CEP14083, CEP2550, CEP28122) and -EGFR inhibitors resulted in an increased cell death of H2228 cells to values similar to those observed for ALK treated H3122 cells. Finally, gene expression analyses showed that known EGFR substrates were specifically down regulated upon the combined treatment in ALK positive H2228 cells.
Our findings suggest that ALK signaling is required for the maintenance of the neoplastic phenotype of some ALK positive NSCLC cells and that its abrogation could represent a novel strategy for the treatment of a well-defined subset of human lung cancer (complete ALK addiction). More importantly, we showed that the tumor survival and maintenance of ALK positive neoplastic cells might relay on the concomitant activation of multiple RTKs. These findings further support the notion that molecular and functional signatures are required for designing molecular-based “patient specific” therapeutic protocols in lung cancer patients.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-309.