Fig. 1

TET2 deficiency elicits EGFR-TKI resistance in NSCLC. a Global 5hmC levels in osimertinib-resistant (OR) and its paired treatment naïve PC-9 and HCC827 cell lines were determined by dot blot assay. The methylene blue staining was used as total genomic DNA loading control. b Treatment naïve and its paired OR cell lines (PC-9 and HCC827) was subjected to immunoblot (IB) analysis. c Global 5hmC levels in treatment naïve and its paired EGFR-TKI resistant cell lines (PC-9 and HCC827) was determined by dot blot assay. The methylene blue staining was used as total genomic DNA loading control. d TET2 protein expression level in indicated cell lines were determined by immunoblots. e mRNA level of TET2 in indicated cells. f IHC score of TET2 expression in specimens from NSCLC patients who were treatment naïve or osimertinib-resistant. n = 30 in naïve group and n = 32 in resistant group. g Representative IHC staining of TET2 in paired specimens from one of the EGFR-mutant NSCLC patients as shown in (f). Scale bars, 50 μm. IC50 values of indicated EGFR-TKI in HCC827 (h) and PC-9 (i) cells with or without TET2 knockdown using shRNA. Right panel, immunoblots to confirm the knockdown efficiency of TET2 in indicated cells. Growth curves of xenograft tumors derived from HCC827 (j) and PC-9 (k) cells with or without TET2 knockout following osimertinib treatment (2.5 mg/kg, daily, i.p.) or not (n = 6 mice per group). GR gefitinib-resistant, ER erlotinib-resistant, AR afatinib-resistant, OR osimertinib resistant. Statistical source data for (f) are shown in Supplementary Table 1. P values were calculated using two-tailed unpaired Student’s t tests (f, h, i) and Two way ANOVA (j, k)