Its culture supplement

All cell lines used in this study are described in Supplementary Table 1 and were obtained from the COG/ALSF Childhood Cancer Repository (www.CCcells.org). Neuroblastoma cell lines used in the study were cultured in complete medium of Iscove’s Modified Dulbecco’s Medium (Thermo Scientific) supplemented with 20% fetal bovine serum (FBS) (Gibco – Life Technologies), 4 mmol/L L-glutamine (Corning Cellgro), insulin and transferrin (20 mg/mL each), and selenous acid (20 ng/mL; ITS Culture Supplement; BD Biosciences). Cell line and patient-derived xenograft identities were verified via short-tandem repeat (STR) profiling by GenePrint® 10 System from Promega validated against a searchable online database at www.CCcells.org, before starting and at the conclusion of the experiments, and were confirmed to be free of mycoplasma with MycoAlert Mycoplasma detection kit from Lonza. Cells were cultured and treated in a 37 deg C humidified incubator gassed with 5% CO₂ and 90% N₂, to achieve bone marrow level hypoxia of 5% O₂ (27 (link)). Cell lines with the “h” suffix were established in and only cultured in 5% O_2.

Tacrine hydrochloride and MK571 were obtained from Cayman Chemical Company (Ann Arbor, MI). Collagenase (type I, class I), rat tail collagen (type I), Dulbecco’s modified Eagle’s medium (DMEM), and insulin were purchased from Invitrogen (Carlsbad, CA). Fluvoxamine maleate, verapamil hydrochloride, 5 - (and – 6) – carboxy - 2’, 7 ’-dichlorofluorescein diacetate (CDFDA), dexamethasone, tetraethylammonium chloride (TEA), bovine serum albumin (BSA), soybean trypsin inhibitor, and fetal bovine serum (FBS) were purchased from Sigma-Aldrich (St. Louis, MO). ITS culture supplement (10μg/ml insulin, 10μg/ml transferrin, 10ng/ml selenous acid) was obtained from BD Biosciences (San Jose, CA). Valspodar was obtained from XenoTech (Lenexa, KS). Total protein measurement’s reagents with the bicinchoninic acid (BCA) method were from Pierce (Rockford, IL). All other chemicals and reagents were of analytical grade and were readily available from commercial sources.