9L gliosarcoma cell proliferation and tumor growth in rats are suppressed by N-hydroxy-N'-(4-butyl-2-methylphenol) formamidine (HET0016), a selective inhibitor of CYP4A

J Pharmacol Exp Ther. 2006 Apr;317(1):97-108. doi: 10.1124/jpet.105.097782. Epub 2005 Dec 13.


The present study examined the effects of N-hydroxy-N'-(4-butyl-2 methylphenyl) formamidine (HET0016), a selective inhibitor of the formation of 20-hydroxyeicosatrienoic acid (20-HETE) on the growth of 9L rat gliosarcoma cells in vitro and in vivo. After 48 h of incubation, HET0016 reduced the proliferation of 9L in vitro by 55%, and this was associated with a fall in p42/p44 mitogen-activated protein kinase and stress-activated protein kinase/c-Jun NH(2)-terminal kinase phosphorylation and increased apoptosis. HET0016 inhibited epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)-induced proliferation and diminished phosphorylation of PDGF receptors. A stable 20-HETE analog increased 9L cell proliferation. In vivo, chronic administration of HET0016 (10 mg/kg/day i.p.) for 2 weeks reduced the volume of 9L tumors by 80%. This was accompanied by a 4-fold reduction in the mitotic index, a 3- to 4-fold increase in the apoptotic index, and a approximately 50% decrease in vascularization in the tumor. HET0016 treatment increased mean survival time of the animals from 17 to 22 days. Liquid chromatography/mass spectrometry experiments indicated that neither 9L cells grown in vitro nor 9L tumors removed produce 20-HETE when incubated with arachidonic acid. The normal surrounding brain tissue, however, avidly makes 20-HETE, and this activity is selectively inhibited by HET0016. These results suggest that HET0016 may be the prototype of a class of antigrowth compounds that may be efficacious for treating malignant brain tumors. In vivo, it may act in part by inhibiting the formation of 20-HETE by the surrounding tissue. However, the antiproliferative effects of HET0016 on 9L cells in vitro seem unrelated to its ability to inhibit the formation of 20-HETE.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amidines / pharmacology
  • Amidines / therapeutic use*
  • Animals
  • Apoptosis / drug effects
  • Arachidonic Acid / metabolism
  • Brain Neoplasms / drug therapy*
  • Brain Neoplasms / pathology
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Cerebral Cortex / pathology
  • Cytochrome P-450 CYP4A / antagonists & inhibitors*
  • Enzyme Inhibitors / pharmacology
  • Enzyme Inhibitors / therapeutic use*
  • Gliosarcoma / drug therapy*
  • Gliosarcoma / pathology
  • Male
  • Neoplasm Transplantation
  • Rats
  • Rats, Inbred F344


  • Amidines
  • Enzyme Inhibitors
  • HET0016
  • Arachidonic Acid
  • Cytochrome P-450 CYP4A