Figure 2.

Role of nucleoside transporters in the uptake of DNMT inhibitors and in drug-induced chemosensitivity. (A) Uptake of [³H]-labelled nucleoside-derived drugs and uridine (1 μM, 1 min) by hCNT1 or hCNT3 was measured in transport medium containing 137 mM NaCl or 137 mM choline chloride. Sodium-dependent transport was calculated as uptake in NaCl medium minus uptake in choline chloride medium in HeLa transiently transfected cells. For equilibrative transport, the endogenous activity was measured in HeLa cells using sodium-depleted medium (n = 3). (B–D) HeLa cell viability was measured after 48 h drug exposure to hCNT1, hCNT3 or mock-transfected HeLa cells. Values were fitted to a non-linear regression curve (n = 3).