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. Author manuscript; available in PMC: 2012 Sep 1.
Published in final edited form as: Nat Cell Biol. 2012 Feb 19;14(3):276–286. doi: 10.1038/ncb2432

Figure 5. Leukemia cells (CLL) exhibited low ability to directly utilize cystine and were dependent on stromal cells to convert cystine to cysteine for GSH synthesis.

Figure 5

(A) Expression of the cystine transporter xCT in HS5 (H), StromaNKtert (N), and KUSA-H1 (K) stromal cells and primary CLL cells from patients (n=10). The un-cropped blots are shown as Supplementary Information. (B) Comparison of [14C]cystine uptake by HS5 stromal cells and CLL cells (4 h incubation). Bar graph of mean ± SD of 3 separate experiments is shown (***, p<0.001). (C) Effective uptake of [14C]cysteine, but not [14C]cystine by CLL cells (4 h incubation; mean ± SD; n=3 patient samples; ***, p<0.001). (D) Stromal cells (HS5) increased the uptake of radioactivity by CLL cells in culture medium containing [14C]cystine (6 h incubation; mean ± SD; n=3 patient samples; ***, p<0.001). (E) Extracellular cystine was required for stromal cells to enhance GSH synthesis in CLL cells. CLL cell were co-culture with HS5 cells in presence or absence of 200 μM cystine for 72 h, and GSH contents in CLL cell extracts were measured (mean ± SD; n=3 patient samples; *, p<0.05; **, p<0.01).