Thymidine kinase, thymidylate synthase, and dihydropyrimidine dehydrogenase profiles of cell lines of the National Cancer Institute's Anticancer Drug Screen.
OBJECTIVE
To determine the expression of three targets of 5-fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FdUrd) in human tumor cell lines and to compare these with the 50% growth inhibition concentrations (GI(50)) from the National Cancer Institute database.


METHODS
Thymidine kinase (TK) activity was assessed by conversion of [(3)H]thymidine to [(3)H]TMP. Thymidylate synthase (TS) protein expression was determined by Western analysis. TS and dihydropyrimidine dehydrogenase (DPD) mRNA expression were measured by quantitative reverse transcription-PCR.


RESULTS
The median (range) for the targets were as follows: 5-FU GI(50), 20.8 microM (0.8-536); FdUrd GI(50), 0.75 microM (0.25-237); TK, 0.93 nmol/min/mg (0.16-5.7); in arbitrary units: TS protein, 0.41 (0.05-2.95); TS mRNA, 1.05 (0.12-6.41); and DPD mRNA, 1.09 (0.00-24.4). A moderately strong correlation was noted between 5-FU and FdUrd GI(50)s (r = 0.60), whereas a weak-moderate correlation was seen between TS mRNA and protein expression (r = 0.45). Neither TS expression nor TK activity correlated with 5-FU or FdUrd GI(50)s, whereas lines with lower DPD expression tended to be more sensitive to 5-FU. Cell lines with faster doubling times and wild-type p53 were significantly more sensitive to 5-FU and FDURD:


CONCLUSIONS
The lack of correlation may in part be attributable to the influence of downstream factors such as p53, the observation that the more sensitive cell lines with faster doubling times also had higher TS levels, and the standard procedure of the screen that uses a relatively short (48-h) drug exposure.
Grem
J L
JL
Developmental Therapeutics Department, Medicine Branch, Division of Clinical Sciences, National Cancer Institute at the National Naval Medical Center, Bethesda, Maryland 20889, USA.
Danenberg
K D
KD
Behan
K
K
Parr
A
A
Young
L
L
Danenberg
P V
PV
Nguyen
D
D
Drake
J
J
Monks
A
A
Allegra
C J
CJ
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D016208:Databases, Factual; D042943:Dihydrouracil Dehydrogenase (NADP); D004354:Drug Screening Assays, Antitumor; D005467:Floxuridine / Q000494:pharmacology*; D005472:Fluorouracil / Q000494:pharmacology*; D006801:Humans; D009154:Mutation / Q000187:drug effects; D009316:National Institutes of Health (U.S.); D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D013937:Thymidine Kinase / Q000378:metabolism*; D013940:Thymidylate Synthase / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D014481:United States
D000964:Antimetabolites, Antineoplastic; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D005467:Floxuridine; D004247:DNA; D010088:Oxidoreductases; D042943:Dihydrouracil Dehydrogenase (NADP); D013940:Thymidylate Synthase; D013937:Thymidine Kinase; D005472:Fluorouracil; D013936:Thymidine