Treatment of pancreatic cancer cells with dicumarol induces cytotoxicity and oxidative stress.
OBJECTIVE

quinone oxidoreductase (NQO(1)) catalyzes the two-electron reduction of quinones to hydroquinones. This reaction is believed to prevent the one-electron reduction of quinones that would result in redox cycling with generation of superoxide (O(2)(.-)). We have recently demonstrated that inhibition of NQO(1) with dicumarol increases intracellular O(2)(.-) production and inhibits the in vitro malignant phenotype of pancreatic cancer cells (J. Cullen et al., Cancer Res., 63: 5513-5520, 2003). We hypothesized that inhibition of NQO(1) would increase cell killing, induce oxidative stress, and inhibit in vivo tumor growth.


RESULTS
In the human pancreatic cancer cell line MIA PaCa-2, dicumarol decreased cell viability, as measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and decreased clonogenic survival. Dicumarol increased the percentage of apoptotic cells in a time-dependent and dose-dependent manner as measured by 3,3'-diaminobenzidine staining and flow cytometry, which was associated with cytochrome c release and poly(ADP-ribose) polymerase cleavage. Dicumarol also induced oxidative stress as evidenced by increased total glutathione and oxidized glutathione, as well as sensitizing to cell killing mediated by menadione. In established orthotopic pancreatic tumors in nude mice, intratumoral injections of dicumarol slowed tumor growth and extended survival.


CONCLUSIONS
Inhibition of NQO(1) with dicumarol induces cell killing and oxidative stress in pancreatic cancer cells and speculate that dicumarol may prove to be useful in pancreatic cancer therapeutics.
Lewis
Anne
A
Department of Surgery, Radiation Oncology and Holden Comprehensive Cancer Center, and University of Iowa College of Medicine, Iowa City, Iowa, USA.
Ough
Matthew
M
Li
Ling
L
Hinkhouse
Marilyn M
MM
Ritchie
Justine M
JM
Spitz
Douglas R
DR
Cullen
Joseph J
JJ
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival; D045304:Cytochromes c / Q000378:metabolism; D001728:Dicumarol / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004583:Electrons; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000037:antagonists & inhibitors; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000188:drug therapy*; D010641:Phenotype; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011808:Quinone Reductases / Q000378:metabolism; D013997:Time Factors; D014475:Uncoupling Agents / Q000494:pharmacology; D024483:Vitamin K 3 / Q000378:metabolism
D004791:Enzyme Inhibitors; D006873:Hydroquinones; D014475:Uncoupling Agents; D024483:Vitamin K 3; D001728:Dicumarol; D045304:Cytochromes c; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; C087049:NADPH - phenanthrenequinone oxidoreductase; D011808:Quinone Reductases; D011065:Poly(ADP-ribose) Polymerases; D005978:Glutathione; D010100:Oxygen