Fig. 1

Intercellular transfer of exosomal wtEGFR protein confers osimertinib resistance to mutEGFR cancer cells in vitro. a-b Representative images of H1299 cells (GFP) alone, H1975 cells (RFP) alone or H1975 cells (RFP) co-cultured with H1299 cells (GFP) at a ratio of 1:1 treated by osimertinib (5 μM) for 72 h. Scale bar: 100 μm. c MTT assay of H1975 cells grown on the lower chamber indirectly pre-cultured with H460 cells, A549 cells and H1299 cells or control H1975 cells grown inside the transwell inserts (pores 0.4 μm) for 36 h. d MTT assay of H1975 cells pre-cultured with CM of H460 cells, A549 cells and H1299 cells or control H1975 cells for 36 h. e MTT assay of H1975 cells and PC9 cells pre-cultured with or without exosomes derived from H1299 cells for 6 h. f MTT assay of H1975 cells pre-cultured with CM or CM dExo derived from H1299 cells for 36 h. g-h Flow cytometric Annexin V/PI Apoptosis assay of H1975 cells pre-cultured with various concentration of exosomes for 6 h following osimertinib treatment (5 μM) for another 36 h. i MTT assay of H1975 cells pre-cultured with indicated exosomes (con, IgG or cetuximab pre-treated) derived from H1299 cells for 6 h. j-k Flow cytometric Annexin V/PI Apoptosis assay of H1975 cells pre-cultured with CM of K562 cells for 36 h following osimertinib treatment (5 μM) for another 36 h. All data are presented as means ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001