Hypoxia-inducible factor (HIF) is a key regulator of
tumor growth and angiogenesis. Recent studies have shown that,
BIX01294, a G9a
histone methyltransferase (HMT)-specific inhibitor, induces apoptosis and inhibits the proliferation, migration, and invasion of
cancer cells. However, not many studies have investigated whether inhibition of G9a HMT can modulate HIF-1α stability and angiogenesis. Here, we show that
BIX01294 dose-dependently decreases levels of HIF-1α in HepG2 human
hepatocellular carcinoma cells. The half-life of HIF-1α, expression of
proline hydroxylase 2 (PHD2), hydroxylated HIF-1α and von Hippel-Lindau
protein (pVHL) under hypoxic conditions were decreased by
BIX01294. The
mRNA expression and secretion of
vascular endothelial growth factor (
VEGF) were also significantly reduced by
BIX01294 under hypoxic conditions in HepG2 cells.
BIX01294 remarkably decreased angiogenic activity induced by
VEGF in vitro, ex vivo, and in vivo, as demonstrated by assays using human umbilical vein endothelial cells (HUVECs), mouse aortic rings, and chick chorioallantoic membranes (CAMs), respectively. Furthermore,
BIX01294 suppressed
VEGF-induced
matrix metalloproteinase 2 (MMP2) activity and inhibited
VEGF-induced phosphorylation of
VEGF receptor 2 (VEGFR-2),
focal adhesion kinase (FAK), and
paxillin in HUVECs. In addition,
BIX01294 inhibited
VEGF-induced formation of actin cytoskeletal stress fibers. In conclusion, we demonstrated that
BIX01294 inhibits HIF-1α stability and
VEGF-induced angiogenesis through the
VEGFR-2 signaling pathway and actin cytoskeletal remodeling, indicating a promising approach for developing novel
therapeutics to stop
tumor progression.