Fig. 6: Pharmacological inhibition of ISR impairs KRAS lung tumor growth.

a, b H1299 cells overexpressing either wild type KRAS (a) or KRAS G12C (b) were transplanted subcutaneously in nu/nu mice followed by treatments with vehicle control (n = 8 for wild type KRAS; n = 6 for KRAS G12C), 10 mg/kg ISRIB (n = 10 for wild type KRAS; n = 8 for KRAS G12C) or 150 mg/kg PERK inhibitor GSK2606414 (PERKi) (n = 10 for wild type KRAS; n = 6 KRAS G12C). Data represent mean ± SEM, two-sided one-way ANOVA, Dunnett’s multiple comparison test, P values are indicated on the graph. c, d LLC cells were orthotopically injected into the lungs of immune-competent C57BL/6 mice. Mice were subjected to treatments on day 12 after the intratracheal intubation of LLC cells. The graph in panel c indicates lung tumor volume at the indicated weeks of tumor growth as analyzed by ultrasound imaging of mice treated with vehicle (n = 6), 10 mg/kg ISRIB (n = 6), and 150 mg/kg PERKi (n = 7). Data represent mean ± SEM, two-sided one-way ANOVA, Dunnett’s multiple comparison test, P values are indicated on the graph. d H&E staining along with the expression of nuclear ATF4, nuclear p-ERK and cytoplasmic DUSP6 in vehicle-control or ISRIB-treated LLC tumors at the sixth week of treatment. Scale bars correspond to 200 and 60 µm of core and enlarged tumor images, respectively. e, f Immune-competent mice bearing KRAS G12D lung tumors were subjected to treatments with either vehicle (n = 9) or 10 mg/kg ISRIB (n = 6). Ultrasound imaging in panel e indicates lung tumor formation in live mice at 24 or 38 weeks after treatment initiation. Graphs indicate tumor volume assessed by ultrasound imaging. The survival curve in (f) refers to immune-competent mice bearing KRAS G12D tumors treated with either vehicle control (n = 9) or 10 mg/kg ISRIB (n = 6). Arrowhead indicates initiation of drug treatment 10 weeks after KRAS G12D induction in the lungs by the intratracheal intubation of CRE-expressing lentiviruses, at which point detectable lung tumors were formed (Supplementary Fig. 11b). d, f Data represent mean ± SEM. Significance in differences between two datasets was determined using two-tailed unpaired t-test. P values are indicated on the bar graph.