Suppression of VEGF secretion and changes in glioblastoma multiforme microenvironment by inhibition of integrin-linked kinase (ILK).
Integrin-linked kinase (ILK) was assesed as a therapeutic target in glioblastoma xenograft models through multiple endpoints including treatment related changes in the tumor microenvironment. Glioblastoma cell lines were tested in vitro for sensitivity toward the small-molecule inhibitors QLT0254 and QLT0267. Cell viability, cell cycle, and apoptosis were evaluated using MTT assay, flow cytometry, caspase activation, and DAPI staining. Western blotting and ELISA were used for protein analysis (ILK, PKB/Akt, VEGF, and HIF-1alpha). In vivo assessment of growth rate, cell proliferation, BrdUrd, blood vessel mass (CD31 labeling), vessel perfusion (Hoechst 33342), and hypoxia (EF-5) was done using U87MG glioblastoma xenografts in RAG2-M mice treated orally with QLT0267 (200 mg/kg q.d.). ILK inhibition in vitro with QLT0254 and QLT0267 resulted in decreased levels of phospho-PKB/Akt (Ser473), secreted VEGF, G2-M block, and apoptosis induction. Mice treated with QLT0267 exhibited significant delays in tumor growth (treated 213 mm3 versus control 549 mm3). In situ analysis of U87MG tumor cell proliferation from QLT0267-treated mice was significantly lower relative to untreated mice. Importantly, VEGF and HIF-1alpha expression decreased in QLT0267-treated tumors as did the percentage of blood vessel mass and numbers of Hoechst 33342 perfused tumor vessels compared with control tumors (35% versus 83%). ILK inhibition with novel small-molecule inhibitors leads to treatment-associated delays in tumor growth, decreased tumor angiogenesis, and functionality of tumor vasculature. The therapeutic effects of a selected ILK inhibitor (QLT0267) should be determined in the clinic in cancers that exhibit dysregulated ILK, such as PTEN-null glioblastomas.
Edwards
Lincoln A
LA
Department of Advanced Therapeutics, BC Cancer Agency, Vancouver, British Columbia, Canada.
Woo
Janet
J
Huxham
Lynsey A
LA
Verreault
Maite
M
Dragowska
Wieslawa H
WH
Chiu
Gigi
G
Rajput
Ashish
A
Kyle
Alastair H
AH
Kalra
Jessica
J
Yapp
Donald
D
Yan
Hong
H
Minchinton
Andrew I
AI
Huntsman
David
D
Daynard
Tim
T
Waterhouse
Dawn N
DN
Thiessen
B
B
Dedhar
Shoukat
S
Bally
Marcel B
MB
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D045744:Cell Line, Tumor; D005909:Glioblastoma / Q000098:blood supply / Q000188:drug therapy / Q000201:enzymology* / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008297:Male; D051379:Mice; D015394:Molecular Structure; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D042442:Vascular Endothelial Growth Factors / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays; D000099200:Scaffold Protein ILK
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D042442:Vascular Endothelial Growth Factors; D000099200:Scaffold Protein ILK; C497442:HIF1A protein, human