Figure 6: Inhibition of EGFR activity attenuates MYBL2 and A3B expression.

(A) Histogram showing each MYBL2 and A3B expression value and 95% confidence interval relative to TBP expression. T47D cells that had been treated with 10 μM afatinib, 10 μM AZD9291, 2 μM PD153035, 10 μM AEB071, or 1 μM U0126 for 24 h were subjected to RNA extraction for gene expression analysis by quantitative RT-PCR. Asterisks indicate that MYBL2 or A3B expression in those treatments differed significantly from that of the DMSO treatment (control). (B) As in (A), T47D cells that had been treated with 10 μM afatinib, 10 μM AZD9291, or DMSO for 30 min were incubated with 25 or 100 ng/ml EGF for 24 h before RNA extraction. (C) Histogram showing the median value and 5th–95th percentile range of the A3B RMA values from 829 GDSC cell lines. Statistical significance between two groups was determined with the Student’s t-test (P for trend = 0.0264). EGFR copy number status was defined as follows: normal, copies ≤2 (248 cell lines); increased, 3≤ copies ≤7 (560 cell lines); amplified, copies ≥8 (21 cell lines). (D) Dot plot showing afatinib sensitivity, presented by AUC values, in different groups based on low (black circle), middle (blue circle), and high (pink circle) third ranks of A3B RMA values. Cell lines listed on the x axis were ranked according to afatinib sensitivity. The AUC values in the low third group were statistically different from those in the middle and high third groups at P < 0.0001 and P = 0.0023, respectively (Mann–Whitney U-test).