Figure 1. ABL kinase inhibitors impair SCLC metastases, downregulate DNA repair and DNA replication pathways, and enhance DNA damage in SCLC cells.

(A) H69 SCLC cells were intracardiac injected into nude mice and monitored by bioluminescence imaging (BLI). Mice were treated by oral gavage twice daily with vehicle or the ABL kinase inhibitor GNF5 (100 mg/kg) starting at day 17 post-injection. Mice were imaged at day 43 by BLI.

(B) Percentage of mice surviving over the indicated times (days). Log rank (Mantel-Cox) test: *p = 0.0178. Mice number n = 8 each group.

(C and D) H69 cells were treated with GNF5 (20 μM) or vehicle DMSO for 48h. Gene set enrichment analysis of DNA repair (C) and DNA replication (D) signature genes using total RNA-seq data.

(E and F) H69 (E), H146 (F) SCLC cells were treated with GNF5 (G, 20 μM), ABL001 (A, 20 μM), GMB475 (GMB, 10 μM) or vehicle DMSO (C) for 48 h. Cell lysates were analyzed by western blotting with indicated antibodies.

(G) DMS53 cells were treated with GMB475 (10 μM) or vehicle DMSO (control) for 24 h. Immunofluorescence (IF) staining was performed with anti-γH2AX antibody, plus Alexa Fluor 568-coupled secondary antibody. DAPI was used for nucleus staining (left panel) (scale bars, 10 μm). The γH2AX foci were quantified, n = 80 nuclei each (right panel). Student’s t test ****p = 0.0006.

(H) U2OS-Tet-DR-GFP cells transfected with I-SceI-mCherry were treated with ABL001 (20 μM) or GMB475 (10 μM) or vehicle DMSO plus or minus doxycycline (1 μg/mL) for 60 h. Cells were then analyzed by flow cytometry.

Percentage of mCherry and GFP double-positive cells was calculated over total mCherry-positive cells. Data were analyzed with a one-way ANOVA. ****p < 0.0001, *p = 0.03, and ***p = 0.0008.

Data in B and F represented by mean +/− SEM.