Figure 4.

IRAK1 Knockdown Enhanced EGFR TKI-Mediated Apoptosis

(A) After transfections of siCTL or siIRAK1 for 24 h, PC9/gef cells were pre-treated with Z-VAD (50 μM) before treatments with vehicle or gefitinib (1 μM). (B) After transfections with siCTL or siIRAK1 and incubation for 24 h, cells were treated with vehicle or osimertinib (0.1 μM for PE2988; 0.3 μM for PE3479) for 18 h. The cleavage of caspase-3 and PARP were determined using immunoblotting. (C, D) PC9/gef cells were transfected with siCTL (scrambled control) or siIRAK1 for 24 h, and then treated with the indicated concentrations of erlotinib (C) or afatinib (D) for 72 h. Cell viability was assessed using the MTT assay as described in Materials and Methods. (E) Relative expression levels of IRAK1 mRNA were evaluated in primary cancer cells from the pleural effusions of patients with malignant disease. “Treatment-naive” indicates cancer cells collected from patients at the point of diagnosis and before administration of EGFR TKIs; “acquired resistance” indicates cancer cells from patients with progressive disease after EGFR TKI treatment. The expression of IRAK1 was normalized to TBP expression.