Abstract 3886: Protein mapping of NSCLC cell lines: Defining mechanisms of acquired erlotinib resistance
Authors: Hayes Sarah A. , Krisp Christoph , Hudson Amanda L. , Harvie Rozelle , Hasovits Csilla , Clarke Stephen , Molloy Mark P. , Howell Viive M. 
Published: July 2016

Lung cancer is one of the most common and lethal malignancies globally, with non-small cell lung cancer (NSCLC) accounting for 85% of all lung cancer cases. Patients generally have a poor prognosis without treatment as most patients are diagnosed with advanced metastatic disease, when curative therapeutic options are limited. However, there has been a recent emphasis on identifying driver mutations responsible for patient tumours, which has paved the way for more effective targeted therapies in the treatment of NSCLC.

One such targeted therapy, erlotinib, is used as standard-of-care treatment in NSCLC patients with sensitising EGFR mutations. Although use of these tyrosine kinase inhibitors (TKIs) often leads to dramatic and prolonged response, acquired resistance eventually ensues. Understanding and overcoming the molecular basis of resistance to erlotinib remains a challenge for successful long-term treatment.

To identify mechanisms of erlotinib resistance, we used latest-generation mass spectrometry to comprehensively map the proteomes of two NSCLC cell lines: a parental NSCLC cell line sensitive to erlotinib (HCC827, contains a deletion in EGFR exon 19) and its matched erlotinib-resistant subline (HCC827_ER). Cell lines were treated with an IC50 dose of erlotinib or mock treatment. Three days after treatment, each cell line was profiled using the Sequential Windowed data independent Acquisition of the Total High-resolution Mass Spectra (SWATH-MS 2.0) algorithm, conducted on the Sciex 6600 TripleTOF. LC-MS/MS data was extracted for 3416 proteins (peptide confidence &gt;99%) following a Sciex ProteinPilot database search.

Overall, 33 proteins were differentially expressed between HCC827 mock and erlotinib treated cells, while expression levels of 59 proteins were significantly different between HCC827er mock and erlotinib treated cells (Fold Change&gt;2, p&lt;0.05). Ingenuity Pathway Analysis listed “Organismal Injury and Abnormalities” and “Cancer” as the leading Diseases and Disorders in both cell lines, with “Cellular Growth and Proliferation” and “Small Molecule Biochemistry” listed as the top Molecular and Cellular Functions in the sensitive and resistant cell line, respectively. In the parental cell line, identified proteins were associated with the regulation of the actin cytoskeleton, as well as the PI3K-Akt signaling pathway, which is commonly altered in human cancers. In the resistant subline, several differentially expressed proteins mapped to various metabolic pathways (including carbon, glycine, serine and threonine metabolism), with some proteins similarly involved in PI3K-Akt signaling.

This is the first time that lung cancer cell lines have been comprehensively profiled by SWATH-MS. Protein mapping will help to increase the understanding of the mechanisms involved in the acquisition of TKI resistance, which is crucial for the development of rational strategies to overcome resistance in the clinic.

Citation Format: Sarah A. Hayes, Christoph Krisp, Amanda L. Hudson, Rozelle Harvie, Csilla Hasovits, Stephen Clarke, Mark P. Molloy, Viive M. Howell. Protein mapping of NSCLC cell lines: Defining mechanisms of acquired erlotinib resistance. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3886.