Induction of interleukin-8 preserves the angiogenic response in HIF-1alpha-deficient colon cancer cells.
Hypoxia inducible factor-1 (HIF-1) is considered a crucial mediator of the cellular response to hypoxia through its regulation of genes that control angiogenesis. It represents an attractive therapeutic target in colon cancer, one of the few tumor types that shows a clinical response to antiangiogenic therapy. But it is unclear whether inhibition of HIF-1 alone is sufficient to block tumor angiogenesis. In HIF-1alpha knockdown DLD-1 colon cancer cells (DLD-1(HIF-kd)), the hypoxic induction of vascular endothelial growth factor (VEGF) was only partially blocked. Xenografts remained highly vascularized with microvessel densities identical to DLD-1 tumors that had wild-type HIF-1alpha (DLD-1(HIF-wt)). In addition to the preserved expression of VEGF, the proangiogenic cytokine interleukin (IL)-8 was induced by hypoxia in DLD-1(HIF-kd) but not DLD-1(HIF-wt) cells. This induction was mediated by the production of hydrogen peroxide and subsequent activation of NF-kappaB. Furthermore, the KRAS oncogene, which is commonly mutated in colon cancer, enhanced the hypoxic induction of IL-8. A neutralizing antibody to IL-8 substantially inhibited angiogenesis and tumor growth in DLD-1(HIF-kd) but not DLD-1(HIF-wt) xenografts, verifying the functional significance of this IL-8 response. Thus, compensatory pathways can be activated to preserve the tumor angiogenic response, and strategies that inhibit HIF-1alpha may be most effective when IL-8 is simultaneously targeted.
Mizukami
Yusuke
Y
Gastrointestinal Unit, Massachusetts General Hospital and Harvard Medical School, 50 Blossom Street, Boston, Massachusetts 02114, USA.
Jo
Won-Seok
WS
Duerr
Eva-Maria
EM
Gala
Manish
M
Li
Jingnan
J
Zhang
Xiaobo
X
Zimmer
Michael A
MA
Iliopoulos
Othon
O
Zukerberg
Lawrence R
LR
Kohgo
Yutaka
Y
Lynch
Maureen P
MP
Rueda
Bo R
BR
Chung
Daniel C
DC
D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000098:blood supply*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016209:Interleukin-8 / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000503:physiopathology*; D010100:Oxygen / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016209:Interleukin-8; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D006861:Hydrogen Peroxide; D010100:Oxygen