Human U251 glioma cell proliferation is suppressed by HET0016 [N-hydroxy-N'-(4-butyl-2-methylphenyl)formamidine], a selective inhibitor of CYP4A

J Pharmacol Exp Ther. 2005 Nov;315(2):526-33. doi: 10.1124/jpet.105.088567. Epub 2005 Aug 4.


We have previously reported that HET0016 [N-hydroxy-N'-(4-butyl-2 methylphenyl)formamidine], a selective inhibitor of CYP4A and thus 20-HETE (20-hydroxyeicosatetraenoic acid) synthesis, inhibits endothelial cell proliferation and decreases angiogenesis induced by human glioma cell U251. A stable 20-HETE agonist, WIT003 [20-hydroxyeicosa-5(Z),14(Z)-dienoic acid (1 microM)], increased U251 cell proliferation from 3.9- to 4.8-folds from T(0) (time of the treatment). We examined the effects of HET0016 on the growth of U251. HET0016 inhibited U251 basal cell proliferation in a dose-dependent manner. 10 microM HET0016 suppressed 56% of U251 proliferation and significantly increased the proportions of the cells arrested in the G(0)/G(1) phase of the cell cycle. Exposure to HET0016 (as early as 4 h) reduced protein tyrosine and p42/p44 MAPK (mitogen-activated protein kinase) phosphorylation. Furthermore, HET0016 significantly inhibited the U251 proliferation and phosphorylation of both the epidermal growth factor (EGF) receptor and p42/p44 MAPK induced by EGF. CYP4A mRNA and proteins were both present in U251. This suggests that HET0016 inhibited U251 proliferation by inhibiting 20-HETE synthesis. However, U251 did not synthesize 20-HETE in the presence of arachidonic acid. This implies that HET0016 suppresses U251 proliferation by mechanisms that are not yet clear but may involve activities other than inhibition of 20-HETE synthesis. We concluded that HET0016 may be the prototype of novel compounds that suppress human glioma cell proliferation.

Publication types

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

MeSH terms

  • Amidines / pharmacology*
  • Antineoplastic Agents*
  • Arachidonic Acid / metabolism
  • Blotting, Western
  • Brain Neoplasms / pathology*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Chromatography, High Pressure Liquid
  • Cytochrome P-450 CYP4A / antagonists & inhibitors*
  • DNA Fragmentation
  • Enzyme Inhibitors / pharmacology*
  • ErbB Receptors / drug effects
  • Flow Cytometry
  • Glioma / pathology*
  • Humans
  • Hydroxyeicosatetraenoic Acids / biosynthesis
  • In Situ Nick-End Labeling
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitosis / drug effects
  • RNA, Neoplasm / biosynthesis
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • Thymidine / metabolism


  • Amidines
  • Antineoplastic Agents
  • Enzyme Inhibitors
  • HET0016
  • Hydroxyeicosatetraenoic Acids
  • RNA, Neoplasm
  • Arachidonic Acid
  • 20-hydroxy-5,8,11,14-eicosatetraenoic acid
  • Cytochrome P-450 CYP4A
  • ErbB Receptors
  • Mitogen-Activated Protein Kinase 1
  • Thymidine