We also indicate that paclitaxel caused similar changes in the expression H 89 mw and activity of

CDA. Paclitaxel substantially reduced mRNA levels in the same two cells lines in which paclitaxel decreased mRNA levels of dCK. Furthermore, CDA protein expression appears relatively unchanged by paclitaxel, but specific activity appears substantially increased. We also observed similar changes in CDA mRNA, protein and activity in two additional adenocarcinoma cell lines (breast and ovarian). We believe that our data collectively indicates that these changes may be dependent on the histological subtype, since we only observed changes in large cell and squamous cell carcinoma, and not adenocarcinoma cell lines. These experiments will need to be repeated in additional

cell lines representative of these histologies to confirm our findings. The accumulation of gemcitabine and its metabolites were only measurable in H520 cells. Most likely, it is because this cell line was least sensitive to gemcitabine (as noted by higher IC50 values) and therefore, the accumulation of these metabolites exceeded the lower limits of quantitation of the assay. BV-6 manufacturer Of interest, this cell expresses mutant p53, whereas the remaining two cell lines express wild-type p53. The noted differences in sensitivity to gemcitabine could be explained, in part, by p53 expression, since gemcitabine inhibits apoptosis dependent on

p53 status [29]. Furthermore, the changes in the metabolite accumulation in H520 cells appears to reflect changes in dCK and CDA mRNA levels in these cell lines and further supports our findings that the CI corresponds to the ratio of dCK to CDA mRNA levels. The ratio of dCK to CDA mRNA levels could be a useful maker of response in humans. Of note, we observed that the accumulation of gemcitabine and its phosphorylated and deaminated metabolites were unchanged in an ovarian adenocarcinoma cell line; the lack of change in the accumulation of the parent drug and the metabolites in this cell line are consistent with the lack Histone demethylase of changes in mRNA levels. This cell line also expresses mutant p53 and demonstrated IC-50 click here values similat to the IC-50 values of the H520 cell line [30]. Lastly, the accumulation of the diphosphate exceeded the accumulation of the triphosphate in the H520 cells treated with vehicle-control followed by gemcitabine. The triphosphate has been identified as the dominant metabolite. We used lower concentrations than those shown to maximize the accumulation of the triphosphate and harvested the cells and medium after the time of the maximal accumulation of the triphosphate and we believe these differences may explain, in part, why the diphosphate was the dominant metabolite in this cell line [31].