TY - JOUR
T1 - High basal level gene expression of thymidine phosphorylase (platelet- derived endothelial cell growth factor) in colorectal tumors is associated with nonresponse to 5-fluorouracil
AU - Metzger, Ralf
AU - Danenberg, Kathleen
AU - Leichman, C. Gail
AU - Salonga, Dennis
AU - Schwartz, Edward L.
AU - Wadler, Scott
AU - Lenz, Heinz Josef
AU - Groshen, Susan
AU - Leichman, Lawrence
AU - Danenberg, Peter V.
PY - 1998/10
Y1 - 1998/10
N2 - The gene expression levels of the nucleoside cleavage enzyme/angiogenic factor thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor, were measured by quantitative reverse transcription-PCR in 38 pretreatment biopsies of colorectal tumors from patients who were subsequently treated with 5-fluorouracil (5-FUra) and leucovorin (LV). The range of TP gene expression (relative mRNA levels) in those tumors nonresponsive to 5-FUra was much broader than that of the responding tumors. In contrast to in vitro studies that had shown that an increased intracellular level of TP potentiates the activity of 5-FUra by converting it to the more cytotoxic nucleoside form 5-fluoro-2'deoxyuridine, tumors with the highest basal TP expressions were nonresponders to 5-FUra/LV therapy. The mean TP mRNA level in the nonresponding tumors was 2.6-fold higher than that of the responding patients. We had shown previously that high expression of thymidylate synthase (TS), the target enzyme of 5-FUra, was also a predictor of nonresponse to 5-FUra (L. Leichman et al., J. Clin. Oncol., 15: 3223-3229, 1997). TP and TS expressions were found to be independent variables in these tumors, so that low expression levels of both TS and TP in tumors predicted a very high response rate (11 of 14) to 5- FUra/LV as well as a significantly longer survival, whereas none (0 of 24) of the patients with high expression of either TP or TS were responders.
AB - The gene expression levels of the nucleoside cleavage enzyme/angiogenic factor thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor, were measured by quantitative reverse transcription-PCR in 38 pretreatment biopsies of colorectal tumors from patients who were subsequently treated with 5-fluorouracil (5-FUra) and leucovorin (LV). The range of TP gene expression (relative mRNA levels) in those tumors nonresponsive to 5-FUra was much broader than that of the responding tumors. In contrast to in vitro studies that had shown that an increased intracellular level of TP potentiates the activity of 5-FUra by converting it to the more cytotoxic nucleoside form 5-fluoro-2'deoxyuridine, tumors with the highest basal TP expressions were nonresponders to 5-FUra/LV therapy. The mean TP mRNA level in the nonresponding tumors was 2.6-fold higher than that of the responding patients. We had shown previously that high expression of thymidylate synthase (TS), the target enzyme of 5-FUra, was also a predictor of nonresponse to 5-FUra (L. Leichman et al., J. Clin. Oncol., 15: 3223-3229, 1997). TP and TS expressions were found to be independent variables in these tumors, so that low expression levels of both TS and TP in tumors predicted a very high response rate (11 of 14) to 5- FUra/LV as well as a significantly longer survival, whereas none (0 of 24) of the patients with high expression of either TP or TS were responders.
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M3 - Article
C2 - 9796967
AN - SCOPUS:0031722179
SN - 1078-0432
VL - 4
SP - 2371
EP - 2376
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 10
ER -