Inhibition of cytidine deaminase (CDA) contributes to improved gemcitabine sensitivity.

<p><b>A.</b> Levels of CDA mRNA in pancreatic and lung carcinoma cell lines were evaluated by real-time PCR for Panc-1, MIAPaCa-2, BxPC-3, H322, H1299, and H441. Normalized δCt was calculated as 35-(CDA Ct-GAPDH Ct). <b>B. </b>Three pancreatic and three lung cancer cell lines were cultured with just gemcitabine (GEM) alone, or with GEM and 100 mM tetrahydrouridine (THU). IC50 was determined using a colorimetric assay as described in the experimental procedures. Values are means ±SD, and results are representative of 3 independent experiments.