Fig. 6
Spheroid culture reveals metabolic dependency of cancer cells on lipid desaturation. a BT474 cells were cultured in normoxia (20 % O2) or hypoxia (0.1 % O2) for 48 h before lipids were extracted and used to determine the relative amount of diacylglycerol (DG) and phosphatidylcholine (PC) species by LC-MS/MS. Archival tissue from six individual orthotopic xenograft tumours of BT474 cells [14] was also analysed. Statistical comparisons were performed using Student t tests (*p ≤ 0.05). b Lipids were extracted from T47D cells grown in adherent cultures (2D) or as tumour spheroids. Relative distribution of unsaturated and mono- or poly-unsaturated DAG species are shown. c Selected mono-unsaturated lipid species from T47D cells grown in 2D or as tumour spheroids. d, e DU145 cells expressing inducible shRNAs targeting SCD (shSCD #2) or scrambled control (shNTC) were grown as spheroids in the presence of solvent (EtOH) or 0.5 μg/ml doxycycline (DOX). Spheroids taken at day 9 were subjected to quantitative lipid profiling and relative amounts of free fatty acids (FFA, d) and diacylglycerol species (DAG, e) were determined. Data represent the mean ± SEM of three independent biological replicates. Statistical comparisons were performed using Student t tests (*p ≤ 0.05). f Spheroid size was determined at the indicated times. Spheroids taken at day 9 were fixed and subjected to immunohistochemical staining of SCD and H&E staining. g Spheroids of MDA-MB-468 cells were treated with 100 nM of SCD inhibitors for 4 days and spheroid size was determined. Statistical comparisons were performed using Student t test (*p ≤ 0.05)