Interaction of EGFR and MET in acquired EGFR inhibitor resistance

Taraneh Beikbaghban
2019 unpublished
Non-small cell lung cancer (NSCLC) accounts for ~85% of all lung cancers. EGFR mutations in this tumor are common causes for aggressiveness and thus represent a valuable therapeutic target. However, after initial therapy response, resistance develops by various mechanisms including overexpression of other RTKs like Met or acquisition of secondary mutations, e.g. T790M. In this study, we analyzed resistance mechanisms using the human EGFR-driven NSCLC cell line HCC827. First, resistant sublines
more » ... gainst the EGFR inhibitors erlotinib (HCC827/Erlo) and gefitinib (HCC827/Gefi) were generated. Array Comparative Genomic Hybridization (aCGH) and Fluorescence in situ hybridization (FISH) analyses revealed high-level amplification of the EGFR gene locus in the parental cell line, which was reduced but still present in the resistant sublines. Reduction of the EGFR amplicon was accompanied by gain of the MET gene amplification, which interestingly had a different pattern in the two EGFR inhibitor-resistant models. Met upregulation resulted in EGFR inhibitor resistance in the HCC827/Erlo and HCC827/Gefi sublines. Upon Met inhibition by crizotinib, HCC827/Erlo and HCC827/Gefi were re-sensitized towards EGFR inhibitor treatment. Next, the selection was expanded by additional inhibition of Met. For both the HCC827/Erlo and HCC827/Gefi cell lines two additional sublines were generated: one receiving only crizotinib (HCC827/ErloCrizo, HCC827/GefiCrizo) and one with continuous application of the initial EGFR inhibitor and crizotinib (HCC827/Erlo+Crizo, HCC827/Gefi+Crizo). In the sublines selected only with crizotinib, indirect aCGH revealed loss of MET but no change or even gain of EGFR gene copies. Concomitant selection with both RTK inhibitors resulted in a pronounced loss of both amplicons. In these sublines, combination experiments with crizotinib and EGFR inhibitors showed no re-sensitizing effect towards EGFR inhibitors. Interestingly, in the Erlo+Crizo model, a new high-level amplification on chromosome 17q12 was observed, c [...]
doi:10.25365/thesis.56396 fatcat:47h5if3oorfabfug4czlfydju4