Fig. 5.

mtLC-MSCs promote EGFR-wild-type tumor growth and attenuate osimertinib efficacy in subcutaneous xenograft models. A549 cells expressed luciferase and eGFP. (A–G) A549 cells and MSCs were co-implanted. A549 alone group (n = 5); all other groups (n = 11 each). Tumor growth was monitored by live in vivo imaging (A); tumors were collected on day 21 when mice were sacrificed (B); tumor growth curve (C); transcriptional levels of stem-trait and S100A9 targeted genes in sored eGFP-positive A549 cells, three pooled sorted samples were prepared for each group (D,E); and stem-trait protein expression in tumors was assessed by immunohistochemical staining (F,G). (H–L ) A549 cells were co-implanted with EGFR-mt PC-9 cells and mtLC/TF-MSCs to mimic EGFR-mt NSCLC. Experimental scheme, n = 10 per group before osimertinib treatment, n = 5 per group after treatment (H); A549 growth was assessed on day 10 (I); live imaging after osimertinib treatment (J); tumors on day 32 (K); and whole tumor growth curve (L). (M–O) Combined osimertinib with IL-6 blockade in A549/PC-9/mtLC-MSCs co-implanted model. n = 10 mice per group. Live imaging (M); respective tumors per group on day 32 (N); and whole tumor size during treatment (O). Osimertinib (10 mg/kg, i.p., daily). Tocilizumab (5 mg/kg, i.p., every other day). Statistical results were shown as mean ± SEM (tumor growth curves) and mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, **** P < 0.0001. Two-way ANOVA with Dunnett’s multiple comparisons test for tumor growth curves; Student’s t-test for all others. FDR adjustment applied for multiple group comparison