TY - JOUR
T1 - Biochemical and molecular effects of UCN-01 in combination with 5-fluorodeoxyuridine in A431 human epidermoid cancer cells
AU - Grem, Jean L.
AU - Danenberg, Kathleen D.
AU - Kao, Vivian
AU - Danenberg, Peter V.
AU - Nguyen, Diana
PY - 2002
Y1 - 2002
N2 - Concurrent and pre-exposure of A431 human epidermoid cancer cells to UCN-01, an investigational anticancer drug, with 5-fluoro-2′-deoxyuridine (FdUrd), which targets thymidylate synthase, produced more than additive cytotoxicty, A 24-h exposure to 10 nM FdUrd led to inhibition of TS, a 2.5-fold increase in total thymidylate synthase protein content, profound dTTP depletion and a 6.3-fold increase in the ratio of dATP to dTTP, but did not cause single-strand breaks in DNA. However, FdUrd enhanced UCN-01-associated DNA strand breaks. Concurrent thymidine exposure led to repletion of dTTP pools, and cytoprotection against FdUrd alone and with UCN-01. UCN-01 arrested cells in G1, decreased the percentage of FdUrd-treated cells in S phase and reduced FdUrd-DNA incorporation, suggesting the latter was not important for cytotoxicity. Delayed induction of high molecular mass DNA fragmentation and poly(ADP-ribose) polymerase cleavage was observed with the combination of UCN-01 and FdUrd. These findings suggest that while FdUrd-mediated deoxynucleotide imbalance alone was insufficient to induce apoptosis in this p53-mutant cell line, it magnified UCN-01's effects, most likely by interfering with DNA repair. The clinical evaluation of UCN-01 combined with 5-fluoropyrimidines may be of interest.
AB - Concurrent and pre-exposure of A431 human epidermoid cancer cells to UCN-01, an investigational anticancer drug, with 5-fluoro-2′-deoxyuridine (FdUrd), which targets thymidylate synthase, produced more than additive cytotoxicty, A 24-h exposure to 10 nM FdUrd led to inhibition of TS, a 2.5-fold increase in total thymidylate synthase protein content, profound dTTP depletion and a 6.3-fold increase in the ratio of dATP to dTTP, but did not cause single-strand breaks in DNA. However, FdUrd enhanced UCN-01-associated DNA strand breaks. Concurrent thymidine exposure led to repletion of dTTP pools, and cytoprotection against FdUrd alone and with UCN-01. UCN-01 arrested cells in G1, decreased the percentage of FdUrd-treated cells in S phase and reduced FdUrd-DNA incorporation, suggesting the latter was not important for cytotoxicity. Delayed induction of high molecular mass DNA fragmentation and poly(ADP-ribose) polymerase cleavage was observed with the combination of UCN-01 and FdUrd. These findings suggest that while FdUrd-mediated deoxynucleotide imbalance alone was insufficient to induce apoptosis in this p53-mutant cell line, it magnified UCN-01's effects, most likely by interfering with DNA repair. The clinical evaluation of UCN-01 combined with 5-fluoropyrimidines may be of interest.
KW - 7-Hydroxy-staurospaurine
KW - DNA damage
KW - Fluoropyrimidines
KW - Thymidylate synthase
KW - UCN-01
UR - http://www.scopus.com/inward/record.url?scp=0036245507&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0036245507&partnerID=8YFLogxK
U2 - 10.1097/00001813-200203000-00008
DO - 10.1097/00001813-200203000-00008
M3 - Article
C2 - 11984070
AN - SCOPUS:0036245507
SN - 0959-4973
VL - 13
SP - 259
EP - 270
JO - Anti-Cancer Drugs
JF - Anti-Cancer Drugs
IS - 3
ER -