Suppression of VEGF secretion and changes in glioblastoma multiforme microenvironment by inhibition of Integrin-linked kinase (ILK)

Abstract

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-1A). 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 (Ser 473 ), secreted VEGF, G 2 -M block, and apoptosis induction. Mice treated with QLT0267 exhibited significant delays in tumor growth (treated 213 mm 3 versus control 549 mm 3 ). In situ analysis of U87MG tumor cell proliferation from QLT0267-treated mice was significantly lower relative to untreated mice. Importantly, VEGF and HIF-1A 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.

Pressure-Induced Vascular Oxidative Stress Is Mediated Through Activation of Integrin-Linked Kinase 1/βPIX/Rac-1 Pathway

“…In contrast, blocking the effects of high blood pressure on ROS synthesis could represent an alternative effective approach to normalize the oxidative injury. Thus, the identification of the ILK-1/␤PIX/Rac-1 pathway as the local sensor of hypertension-induced vascular dysfunction could allow us to extend the use of a novel class of drugs selectively inhibiting ILK-1, as proposed recently in cancer therapy, 44 to fight vascular dysfunction in hypertension.…”

A critical role of integrin-linked kinase, ch-TOG and TACC3 in centrosome clustering in cancer cells

“…Moreover, several reports demonstrate that ILK has a role in mitosis by regulation of the microtubule cytoskeleton. Mitotic defects have been detected upon ILK depletion in Drosophila S2 cells (Bettencourt-Dias et al, 2004), mouse hepatocytes (Gkretsi et al, 2007) and human glioblastoma cells (Koul et al, 2005;Edwards et al, 2008). It is interesting that, although the cellular phenotypes were not reported in detail in these studies, all of these systems contain supernumerary centrosomes (Weber et al, 1998;Guidotti et al, 2003;Margall-Ducos et al, 2007;Kwon et al, 2008).…”

Integrin signalling adaptors: not only figurants in the cancer story

“…The use of RNAi and antisense oligonucleotides to downregulate ILK expression and small molecule inhibitors to abrogate its kinase activity, has been shown to reverse ILK oncogenic effects in a variety of cancers. Indeed inhibition of either ILK expression or its activity results in decreased cell migration and invasion, metastasis formation, induction of apoptosis in vitro 30,129,130 and in vivo [131][132][133] . In addition, on the basis of the new role of ILK in mitosis 103,104 , the potential targeting of ILK as an anti-mitotic chemotherapeutic might provide a promising alternative to the chemotherapeutics avoiding severe toxic side effects and drug resistance.…”