Figure 7. Activation of GGA2 increases EGFR mediated transformation.

(A) EGFR^MUT PC9 cells expressing shGGA2-6 or shScramble were treated with the doses of erlotinib indicated for seven days and cell viability assessed by Alamar blue. GGA2 knockdown PC9 cells demonstrated significantly decreased viability at 10 nM erlotinib relative to control cells (*p<0.05, two tailed, unpaired t-test). Bars represent average of two biological replicates +/− SEM. (B) EGFR^MUT PC9 and EGFR^MUT H1975 cells were treated with osimertinib through different dosing strategies to derive resistant cell clones over time (see methods section). GGA2 levels were then assessed by Western blot and levels compared between resistant, parental and acutely treated sensitive cells for each cell line. GGA2 is overexpressed in the H1975 osimertinib resistant clone derived through dose escalation (far right) compared to the parental and acutely treated H1975 cells, suggesting it may play a role in TKI resistance.