Cross-talk of lysine acetylome and tyrosine phosphoproteome unveils abnormal cell signaling of acquired resistance to EGFR inhibitors in lung adenocarcinoma

Authors

• Y Qi
• T Maity
• X Zhang
• U Guha

Abstract

EGFR mutations in non-small cell lung cancer are associated with sensitivity to EGFR tyrosine kinase inhibitors (TKIs). Unfortunately, patients have developed osimertinib, a 3rd generation EGFR TKI, drug resistance in clinic. However, the potential mechanisms of osimertinib resistance have not been fully understood. We focus on the crosstalk of tyrosine phosphorylation (pY) and lysine acetylation (lysAc), two critical post translation modifications (PTMs), that may co-regulate the drug resistance. Here, we developed a mass spectrometry based proteomic platform combined with consecutive dual immunoprecipitations for lysAc and pY in an osimertinib sensitive (S) and a resistant (R) lung adenocarcinoma cell lines, PC9 and PC-9-AZR-NCI-1 which is generated from PC9 with high dose osimertinib selection. We quantified ~1000 pY and ~400 lysAc sites using stable isotope labeling in cell culture (SILAC). Of total, 43 lysAc were upregulated whereas 7 sites were downregulated in the resistant cell line while 191 pY sites were upregulated but 53 downregulated in the resistant line. Interestingly, we discovered 54 proteins undergoing both PTMs. For example, cyclin-dependent kinase 1 (CDK1) shows reduced acetylation activity at K33 (sensitive/resistance ratio is 0.45) which is the ATP binding site; while two well-known inhibitory photoablation sites T14 (S/R ratio is 0.55) and Y15 (S/R ratio is 0.57) were downregulated, and another pY site, Y15, was activated in the resistant line. Therefore, we suggest that CDK1 could be a potential drug target to circumvent osimertinib resistance. Next, we plan to use CDK1 phospho-inhibitor to rescue the osimertinib resistance.

Scientific Focus Area: Cancer Biology

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