Mouse lymphoma model and tumor xenografts

The previously described mouse model of Burkitt lymphoma C57BL/6N-Tg(IGL-MYC)3Hm (λ-MYC mice) [35] was obtained from the NCI mouse repository (Strain code 01XA7), backcrossed to C57BL/6J for more than 10 generations, and maintained in heterozygosity in a C57BL/6 J background. Mice were monitored weekly for palpable tumors, commencing at an age of 8 weeks. Males and females were treated with 20 mM BSO (19176, Sigma-Aldrich) in the drinking water starting at 21 days of age, immediately after weaning. The experimental endpoint was 250 days of age unless palpable tumors were detected. At endpoint, mice were sacrificed and the spleen and all tumors from each individual mouse were resected and weighed.

Transduced DG-75 cells (2 × 10⁶) in 0.1 ml of phosphate buffer saline (PBS) were injected subcutaneously in the dorsal flanks of 8-to 10-week-old female NOD.CB17-Prkdcscid/J mice (Charles River Laboratories, Wilmington, MA, USA). All mice were inoculated with control cells in one flank and GCLC-silenced cells in the opposite flank. Tumor masses were removed after 3 weeks and weighted. All animal procedures were approved by the institutional review board. All animal procedures were approved by the CSIC Ethics Committee (ref. 634/2017 and 1053/2021) and by the Madrid Regional authorities (ref. PROEX 215/17 and 093.7/21), and conformed to EU Directive 2010/63EU and Recommendation 2007/526/EC regarding the protection of animals used for experimental and other scientific purposes, enforced in Spanish law under Real Decreto 1201/2005. Overall mouse health was assessed by daily inspection for signs of discomfort, weight loss, or changes in behaviour, mobility, and feeding or drinking habits.