Induction of thymidine phosphorylase expression and enhancement of Furtulon sensitivity by Taxol in a human ovarian carcinoma cell line.
OBJECTIVE
Thymidine phosphorylase (TP) is one of the enzymes involved in the salvage pathways of nucleotide synthesis. The enzyme converts thymidine to thymine and 2'-deoxyribose-1-phosphate and can also metabolize the prodrug 5'-deoxy-5-fluorouridine (Furtulon) to 5-fluorouracil and 5'-deoxy-D-ribose-1-phosphate. The aim of this study was to determine whether Paclitaxel (Taxol) induces TP expression and whether increased TP expression is further sensitized to Furtulon, using a human ovarian carcinoma cell line.


METHODS
KF 28, a single-cell clone of a human ovarian carcinoma cell line, was used. TP expression was assessed by RT-PCR and Western blot analysis. Cell growth was evaluated by MTT assay.


RESULTS
The concentration of Taxol that inhibited the growth of cells to the level of 50% of the control growth was 4.65 +/- 0.35 nM. TP gene expression was significantly increased at 72 hours 1 nM Taxol exposure compared to the control by RT-PCR (p = 0.020). Western blot analysis confirmed that the TP protein level was elevated compared to the control at 72 hours 1 nM Taxol exposure. Cell growth did not significantly differ between the control and 72 hours 1 nM Taxol exposure groups (p = 0.917). After 48 hours treatment with Furtulon followed by 72 hours 1 nM Taxol exposure, cell growth was dose-dependently inhibited in Taxol-treated cells (p = 0.022), but not in non-Taxol-treated cells (p = 0.082).


CONCLUSIONS
Our results show that a low concentration of Taxol is a candidate for increasing TP expression in a human ovarian carcinoma cell line, and that cells with an elevated level of TP expression can be further sensitized to Furtulon. This information might be valuable in the development of new therapeutic interventions for epithelial ovarian cancer.
Hata
Kohkichi
K
Department of Obstetrics and Gynecology, Shimane Medical University, Izumo 693-8501, Japan. hata31@shimane-med.ac.jp
Osaki
Mitsuhiko
M
Kanasaki
Haruhiko
H
Nakayama
Kentaro
K
Fujiwaki
Ritsuto
R
Ito
Hisao
H
Miyazaki
Kohji
K
D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D004357:Drug Synergism; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D005467:Floxuridine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D017239:Paclitaxel / Q000008:administration & dosage / Q000494:pharmacology*; D011355:Prodrugs / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013939:Thymidine Phosphorylase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000964:Antimetabolites, Antineoplastic; D011355:Prodrugs; D005467:Floxuridine; D013939:Thymidine Phosphorylase; D017239:Paclitaxel; C025034:doxifluridine