Evaluation of the antiangiogenic potential of AQ4N.
OBJECTIVE
A number of cytotoxic chemotherapy agents tested at low concentrations show antiangiogenic properties with limited cytotoxicity, e.g., cyclophosphamide, tirapazamine, and mitoxantrone. AQ4N is a bioreductive alkylaminoanthraquinone that is cytotoxic when reduced to AQ4; hence, it can be used to target hypoxic tumor cells. AQ4N is structurally similar to mitoxantrone and was evaluated for antiangiogenic properties without the need for bioreduction.


METHODS
The effect of AQ4N and fumagillin on human microvascular endothelial cells (HMEC-1) was measured using a variety of in vitro assays, i.e., 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, wound scrape, tubule formation, rat aortic ring, and invasion assays. Low-dose AQ4N (20 mg/kg) was also given in vivo to mice bearing a tumor in a dorsal skin flap.


RESULTS
AQ4N (10(-11) to 10(-5) mol/L) had no effect on HMEC-1 viability. AQ4N (10(-9) to 10(-5)mol/L) caused a sigmoidal dose-dependent inhibition of endothelial cell migration in the wound scrape model. Fumagillin showed a similar response over a lower dose range (10(-13) to 10(-9) mol/L); however, the maximal inhibition was less (25% versus 43% for AQ4N). AQ4N inhibited HMEC-1 cell contacts on Matrigel (10(-8) to 10(-5) mol/L), HMEC-1 cell invasion, and sprouting in rat aorta explants. Immunofluorescence staining with tubulin, vimentim, dynein, and phalloidin revealed that AQ4N caused disruption to the cell cytoskeleton. When AQ4N (20 mg/kg) was given in vivo for 5 days, microvessels disappeared in LNCaP tumors grown in a dorsal skin flap.


CONCLUSIONS
This combination of assays has shown that AQ4N possesses antiangiogenic effects in normoxic conditions, which could potentially contribute to antitumor activity.
O'Rourke
Martin
M
Biomedical Sciences Research Institute, University of Ulster, Coleraine, Northern Ireland, United Kingdom.
Ward
Claire
C
Worthington
Jenny
J
McKenna
Julie
J
Valentine
Andrea
A
Robson
Tracy
T
Hirst
David G
DG
McKeown
Stephanie R
SR
D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D001011:Aorta / Q000187:drug effects; D015687:Cell Hypoxia; D049109:Cell Proliferation; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D003110:Colonic Neoplasms / Q000188:drug therapy; D003510:Cyclohexanes / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000187:drug effects*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006801:Humans; D007797:Laminin / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008833:Microcirculation; D018919:Neovascularization, Physiologic; D010190:Pancreatic Neoplasms / Q000188:drug therapy*; D011471:Prostatic Neoplasms / Q000188:drug therapy; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012717:Sesquiterpenes / Q000494:pharmacology; D012867:Skin / Q000098:blood supply*; D013524:Surgical Flaps; D014945:Wound Healing / Q000187:drug effects
D020533:Angiogenesis Inhibitors; D000880:Anthraquinones; D000970:Antineoplastic Agents; D003510:Cyclohexanes; D004338:Drug Combinations; D005231:Fatty Acids, Unsaturated; D007797:Laminin; D011509:Proteoglycans; D012717:Sesquiterpenes; C059485:matrigel; C094428:AQ4N; C026211:fumagillin; D003094:Collagen