Fig. 4. Physiological thiamine is limiting for ASNase response of SLC19A2-low cells.

(A) Fold change in cell number (log₂) of vector control and SLC19A2 cDNA–expressing REH cells, after untreated or 0.001 U/ml ASNase conditions for 6 days, in the presence (+) or absence (−) of 3 μM thiamine (mean ± SD, n = 3). Media were supplemented with 10% regular FBS, which contributes ~60 nM thiamine. P < 0.05 for all four untreated-treated pairs. (B) Fold change in cell number (log₂) of SLC19A2-low (NALM6 and REH) and SLC19A2-high (JURKAT) wild-type cell lines, after untreated or 0.001 U/ml ASNase conditions for 7 to 9 days, at different thiamine concentrations added to thiamine-free RPMI supplemented with 10% double-dialyzed FBS (mean ± SD, n = 3). P < 0.05 for untreated-treated pairs at these thiamine concentrations: JURKAT, all concentrations; NALM6, all above 1.25 nM; REH, all above 0 nM. (C) ¹³C-thiamine uptake in vector control–, sgSLC19A2_1-, and sgSLC19A2_2-expressing Jurkat cells (mean ± SD, n = 3). (D) Fold change in cell number (log₂) of vector control–, sgSLC19A2_1-, and sgSLC19A2_2-expressing Jurkat cells, after untreated or 0.001 U/ml ASNase conditions for 5 days, at different thiamine concentrations added to thiamine-free RPMI supplemented with 10% double-dialyzed FBS (mean ± SD, n = 3). P < 0.05 for all 15 untreated-treated pairs. Statistics for (A), (B), and (D): two-tailed unpaired t test for equal variances.