Imatinib mesylate

The GIST-T1 cell line, obtained from Cosmo Bio (Japan), was established from a metastatic human GIST that harbors a heterozygous deletion of 57 bases in exon 11 of KIT [41 (link)]. The imatinib-resistant GIST-T1/670 cell clone was derived from GIST-T1 cells upon culture in the presence of 5 μM imatinib and acquired a secondary missense T670I mutation in exon 14 of KIT [11 (link),31 (link),32 (link)]. GIST-T1 cell lines that stably express control shRNA (GIST-T1-Scramble) or shRNAs targeting two distinct regions of LIX1 (GIST-T1-ShLIX1#1 and GIST-T1-ShLIX1#2) were previously developed [29 (link)]. Their characterization by RT-qPCR analysis has confirmed LIX1 downregulation in GIST-T1-ShLIX1 cells with a higher efficacy of ShLIX1#2 than ShLIX1#1 [29 (link)]. All cells were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM, Lonza, France) supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin and routinely tested for the absence of mycoplasma contamination (Venor-GeM OneStep Test, BioValley). GIST cell lines were incubated with imatinib mesylate (STI571, Euromedex, France) and sunitinib (SU11248) malate (SE-S1042, Euromedex, France) at the concentrations indicated in the figure legends.

Imatinib mesylate (imatinib [Cat no. S1026], Euromedex), ABT‐263 (navitoclax [Cat no. S1001], Abbot), and MEK inhibitor (pimasertib [Cat no. S1475], Merck Serono) were purchased from Selleck Chemicals LLC. Puromycin (Cat no. 7130), blasticidin (Cat no. 15202) and doxycycline (Cat no. 9891) were purchased from Sigma‐Aldrich. Annexin V‐APC (Cat no. 640941) and Propidium Iodide (Cat no. 421301) were purchased from BioLegend (Ozyme).