Integrin-Linked Kinase Inhibitor KP-392 Demonstrates Clinical Benefitsin an Orthotopic Human Non-small Cell Lung Cancer Model

Integrin-linked kinase (ILK) regulates KRAS, IPP complex and Ras suppressor-1 (RSU1) promoting lung adenocarcinoma progression and poor survival

Integrin-linked kinase (ILK) forms a heterotrimeric protein complex with PINCH and PARVIN (IPP) in Focal Adhesions (FAs) that acts as a signaling platform between the cell and its microenvironment regulating important cancer-related functions. We aimed to elucidate the role of ILK in lung adenocarcinoma (LUADC) focusing on a possible link with KRAS oncogene. We used immunohistochemistry on human tissue samples and KRAS-driven LUADC in mice, analysis of large scale publicly available RNA sequencing data, ILK overexpression and pharmacological inhibition as well as knockdown of KRAS in lung cancer cells. ILK, PINCH1 and PARVB (IPP) proteins are overexpressed in human LUADC and KRAS-driven LUADC in mice representing poor prognostic indicators. Genes implicated in ILK signaling are significantly enriched in KRAS-driven LUADC. Silencing of KRAS, as well as, overexpression and pharmacological inhibition of ILK in lung cancer cells provide evidence of a two-way association between ILK and KRAS. Upregulation of PINCH, PARVB and Ras suppressor-1 (RSU1) expression was demonstrated in ILK overexpressing lung cancer cells in addition to a significant positive correlation between these factors in tissue samples, while KRAS silencing downregulates IPP and RSU1. Pharmacological inhibition of ILK in KRAS mutant lung cancer cells suppresses cell growth, migration, EMT and increases sensitivity to platinum-based chemotherapy. ILK promotes an aggressive lung cancer phenotype with prognostic and therapeutic value through functions that involve KRAS, IPP complex and RSU1, rendering ILK a promising biomarker and therapeutic target in lung adenocarcinoma.

Differential effects of integrin-linked kinase inhibitor Cpd22 on severe pulmonary hypertension in male and female rats

Pulmonary arterial hypertension (PAH) is a progressive fatal disease with no cure. Inhibition of integrin-linked kinase (ILK) reverses experimental pulmonary hypertension (PH) in male mice, but its effect on severe experimental PH in either male or female animals is unknown. We examined effects of ILK inhibitor Cpd22 on rats with SU5416/hypoxia-induced PH; treatment was performed at six to eight weeks after PH initiation. Five weeks after PH initiation, male and female rats developed similar levels of PH. Eight weeks after PH induction, vehicle-treated male rats had more severe PH than females. Cpd22-treated males, but not females, showed complete suppression of phospho-Akt in small pulmonary arteries (PAs), significantly lower PA medial thickness and percentage of fully occluded arteries, decreased systolic right ventricle (RV) pressure, PA pressure, RV hypertrophy, RV end-diastolic pressure, and improved RV contractility index compared to vehicle-treated group. Cpd22 suppressed proliferation of human male and female PAH pulmonary artery vascular smooth muscle cell (PAVSMC). 17β-estradiol had no effect as a single agent but significantly attenuated Cpd22-dependent inhibition of proliferation in female, but not male, PAH PAVSMC. Taken together, these data demonstrate that male rats develop more severe PH than females but respond better to Cpd22 treatment by reducing pulmonary vascular remodeling, PH, and RV hypertrophy and improving RV functional outcomes. 17β-estradiol diminishes anti-proliferative effect of Cpd22 in female, but not male, human PAH PAVSMC. These findings suggest potential attractiveness of ILK inhibition to reduce established PH in males and suggest that the combination with estrogen-lowering drugs could be considered to maximize anti-proliferative and anti-remodeling effects of ILK inhibitors in females.

OSU-T315 as an Interesting Lead Molecule for Novel B Cell-Specific Therapeutics

B cells are pathogenic in various disease processes and therefore represent an interesting target for the development of novel immunosuppressants. In the search for new therapeutic molecules, we utilized an in vitro B cell activation assay with ODN2006-stimulated Namalwa cells to screen a chemical library of small molecules for B cell modulating effects. OSU-T315, described as an inhibitor of integrin-linked kinase (ILK), was hereby identified as a hit. On human and murine primary B cells, OSU-T315 potently suppressed the proliferation and the production of antibodies and cytokines upon stimulation, suggesting that ILK could be a promising target in the modulation of B cell activity. Mice with B cell-specific knockout of ILK were generated. Surprisingly, knockout of ILK in murine B cells did not affect B cell function as assessed by several in vivo and ex vivo B cell assays and did not alter the B cell immunosuppressive activity of OSU-T315. In conclusion, OSU-T315 displays potency as B cell modulator, probably through a mechanism of action independent of ILK, and might serve as lead drug molecule for the development of novel B cell-selective drugs.

HIPPO-Integrin-linked Kinase Cross-Talk Controls Self-Sustaining Proliferation and Survival in Pulmonary Hypertension

RATIONALE

Enhanced proliferation and impaired apoptosis of pulmonary arterial vascular smooth muscle cells (PAVSMCs) are key pathophysiologic components of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH).

OBJECTIVES

To determine the role and therapeutic relevance of HIPPO signaling in PAVSMC proliferation/apoptosis imbalance in PAH.

METHODS

Primary distal PAVSMCs, lung tissue sections from unused donor (control) and idiopathic PAH lungs, and rat and mouse models of SU5416/hypoxia-induced pulmonary hypertension (PH) were used. Immunohistochemical, immunocytochemical, and immunoblot analyses and transfection, infection, DNA synthesis, apoptosis, migration, cell count, and protein activity assays were performed in this study.

MEASUREMENTS AND MAIN RESULTS

Immunohistochemical and immunoblot analyses demonstrated that the HIPPO central component large tumor suppressor 1 (LATS1) is inactivated in small remodeled pulmonary arteries (PAs) and distal PAVSMCs in idiopathic PAH. Molecular- and pharmacology-based analyses revealed that LATS1 inactivation and consequent up-regulation of its reciprocal effector Yes-associated protein (Yap) were required for activation of mammalian target of rapamycin (mTOR)-Akt, accumulation of HIF1α, Notch3 intracellular domain and β-catenin, deficiency of proapoptotic Bim, increased proliferation, and survival of human PAH PAVSMCs. LATS1 inactivation and up-regulation of Yap increased production and secretion of fibronectin that up-regulated integrin-linked kinase 1 (ILK1). ILK1 supported LATS1 inactivation, and its inhibition reactivated LATS1, down-regulated Yap, suppressed proliferation, and promoted apoptosis in PAH, but not control PAVSMCs. PAVSM in small remodeled PAs from rats and mice with SU5416/hypoxia-induced PH showed down-regulation of LATS1 and overexpression of ILK1. Treatment of mice with selective ILK inhibitor Cpd22 at Days 22-35 of SU5416/hypoxia exposure restored LATS1 signaling and reduced established pulmonary vascular remodeling and PH.

CONCLUSIONS

These data report inactivation of HIPPO/LATS1, self-supported via Yap-fibronectin-ILK1 signaling loop, as a novel mechanism of self-sustaining proliferation and apoptosis resistance of PAVSMCs in PAH and suggest a new potential target for therapeutic intervention.

ILK Induction in Lymphoid Organs by a TNFα-NF-κB-Regulated Pathway Promotes the Development of Chronic Lymphocytic Leukemia

The proliferation of chronic lymphocytic leukemia (CLL) cells requires communication with the lymphoid organ microenvironment. Integrin-linked kinase (ILK) is a multifunctional intracellular adaptor protein that transmits extracellular signals to regulate malignant cell motility, metastasis, and cell-cycle progression, but is poorly characterized in hematologic malignancies. In this study, we investigated the role of ILK in the context of CLL and observed high ILK expression in patient samples, particularly in tumor cells harboring prognostic high-risk markers such as unmutated IGHV genes, high Zap70, or CD38 expression, or a signature of recent proliferation. We also found increased numbers of Ki67 (MKI67)-positive cells in regions of enhanced ILK expression in lymph nodes from CLL patients. Using coculture conditions mimicking the proliferative lymph node microenvironment, we detected a parallel induction of ILK and cyclin D1 (CCND1) expression in CLL cells that was dependent on the activation of NF-κB signaling by soluble TNFα. The newly synthesized ILK protein colocalized to centrosomal structures and was required for correct centrosome clustering and mitotic spindle organization. Furthermore, we established a mouse model of CLL in which B-cell-specific genetic ablation of ILK resulted in decelerated leukemia development due to reduced organ infiltration and proliferation of CLL cells. Collectively, our findings describe a TNFα-NF-κB-mediated mechanism by which ILK expression is induced in the lymph node microenvironment and propose that ILK promotes leukemogenesis by enabling CLL cells to cope with centrosomal defects acquired during malignant transformation. Cancer Res; 76(8); 2186-96. ©2016 AACR.

Using Pharmacokinetic Profiles and Digital Quantification of Stained Tissue Microarrays as a Medium-Throughput, Quantitative Method for Measuring the Kinetics of Early Signaling Changes Following Integrin-Linked Kinase Inhibition in an In Vivo Model of Cancer

A small molecule inhibitor (QLT0267) targeting integrin-linked kinase is able to slow breast tumor growth in vivo; however, the mechanism of action remains unknown. Understanding how targeting molecules involved in intersecting signaling pathways impact disease is challenging. To facilitate this understanding, we used tumor tissue microarrays (TMA) and digital image analysis for quantification of immunohistochemistry (IHC) in order to investigate how QLT0267 affects signaling pathways in an orthotopic model of breast cancer over time. Female NCR nude mice were inoculated with luciferase-positive human breast tumor cells (LCC6^Luc) and tumor growth was assessed by bioluminescent imaging (BLI). The plasma levels of QLT0267 were determined by LC-MS/MS methods following oral dosing of QLT0267 (200 mg/kg). A TMA was constructed using tumor tissue collected at 2, 4, 6, 24, 78 and 168 hr after treatment. IHC methods were used to assess changes in ILK-related signaling. The TMA was digitized, and Aperio ScanScope and ImageScope software were used to provide semi-quantitative assessments of staining levels. Using medium-throughput IHC quantitation, we show that ILK targeting by QLT0267 in vivo influences tumor physiology through transient changes in pathways involving AKT, GSK-3 and TWIST accompanied by the translocation of the pro-apoptotic protein BAD and an increase in Caspase-3 activity.

Role of integrin-linked kinase in osteosarcoma progression

Although integrin-linked kinase (ILK) has been suggested to play a role in the tumorigenesis of a number of human epithelial carcinomas, little is known of its role in musculoskeletal sarcoma. The authors studied ILK expression by immunohistochemistry using osteosarcoma prechemotherapy specimens from 56 patients, and investigated the prognostic implications of the findings obtained. It was found that ILK overexpression was significantly correlated with the presence of distant metastasis (p = 0.008) and that it was an independent prognostic factor for both poor overall survival and poor event-free survival (p = 0.015 and 0.010, respectively). During a transfection experiment conducted by transfecting osteosarcoma cells with ILK siRNA, VEGF concentrations were measured using an ELISA kit, and then compared with those of untransfected controls to evaluate its angiogenic effects. In addition, apoptotic percentages were measured by Annexin-V flow cytometry, and invasive properties were evaluated by measuring the numbers of non-migrating cells in a Boyden chamber. It was found that ILK downregulation significantly decreased angiogenesis, increased apoptosis, and decreased invasiveness of osteosarcoma cells. These results show that ILK is a promising prognostic factor in osteosarcoma and a novel potential therapeutic target for the treatment of osteosarcoma.

There's something about ILK

PURPOSE

Integrin-Linked Kinase (ILK) is associated with integrin and growth factor receptor signalling. As both signalling pathways contribute to cancer cell resistance, ILK seems well suited as a promising tumour target.

MATERIAL AND METHODS

Data were obtained by performing a PubMed database search and summarised with a focus on the function of ILK in cancer biology.

RESULTS

The findings on the catalytic function of ILK, on the putative substrates of ILK and on the expression of ILK in tumour and normal tissues are heterogeneous. In the context of cancer, two of these issues might be of importance. First, a variety of reports indicate a lack of ILK overexpression in tumours. Second, wild-type or overexpression of ILK has been found to considerably sensitise tumour cells to ionising irradiation as compared to ILK knockout or ILK knockdown conditions. In contrast, wild-type or overexpression of ILK has been shown to protect tumour cells from chemotherapy-induced cell death.

CONCLUSIONS

Due to these conflicting data, it is difficult to evaluate if therapeutic targeting of ILK is a reasonable strategy in cancer therapy. A more comprehensive understanding of the molecular mechanisms controlled by ILK may help to answer this question.

The small molecule inhibitor QLT0267 Radiosensitizes squamous cell carcinoma cells of the head and neck

BACKGROUND

The constant increase of cancer cell resistance to radio- and chemotherapy hampers improvement of patient survival and requires novel targeting approaches. Integrin-Linked Kinase (ILK) has been postulated as potent druggable cancer target. On the basis of our previous findings clearly showing that ILK transduces antisurvival signals in cells exposed to ionizing radiation, this study evaluated the impact of the small molecule inhibitor QLT0267, reported as putative ILK inhibitor, on the cellular radiation survival response of human head and neck squamous cell carcinoma cells (hHNSCC).

METHODOLOGY/PRINCIPAL FINDINGS

Parental FaDu cells and FaDu cells stably transfected with a constitutively active ILK mutant (FaDu-IH) or empty vectors, UTSCC45 cells, ILK(floxed/floxed(fl/fl)) and ILK(-/-) mouse fibroblasts were used. Cells grew either two-dimensionally (2D) on or three-dimensionally (3D) in laminin-rich extracellular matrix. Cells were treated with QLT0267 alone or in combination with irradiation (X-rays, 0-6 Gy single dose). ILK knockdown was achieved by small interfering RNA transfection. ILK kinase activity, clonogenic survival, number of residual DNA double strand breaks (rDSB; gammaH2AX/53BP1 foci assay), cell cycle distribution, protein expression and phosphorylation (e.g. Akt, p44/42 mitogen-activated protein kinase (MAPK)) were measured. Data on ILK kinase activity and phosphorylation of Akt and p44/42 MAPK revealed a broad inhibitory spectrum of QLT0267 without specificity for ILK. QLT0267 significantly reduced basal cell survival and enhanced the radiosensitivity of FaDu and UTSCC45 cells in a time- and concentration-dependent manner. QLT0267 exerted differential, cell culture model-dependent effects with regard to radiogenic rDSB and accumulation of cells in the G2 cell cycle phase. Relative to corresponding controls, FaDu-IH and ILK(fl/fl) fibroblasts showed enhanced radiosensitivity, which failed to be antagonized by QLT0267. A knockdown of ILK revealed no change in clonogenic survival of the tested cell lines as compared to controls.

CONCLUSIONS/SIGNIFICANCE

Our data clearly show that the small molecule inhibitor QLT0267 has potent cytotoxic and radiosensitizing capability in hHNSCC cells. However, QLT0267 is not specific for ILK. Further in vitro and in vivo studies are necessary to clarify the potential of QLT0267 as a targeted therapeutic in the clinic.

Integrin-linked kinase--essential roles in physiology and cancer biology

Integrin-linked kinase (ILK) is a multifunctional intracellular effector of cell-matrix interactions and regulates many cellular processes, including growth, proliferation, survival, differentiation, migration, invasion and angiogenesis. The use of recently developed Cre-lox-driven recombination and RNA-interference technologies has enabled the evaluation of the physiological roles of ILK in several major organ systems. Significant developmental and tissue-homeostasis defects occur when the gene that encodes ILK is deleted, whereas the expression of ILK is often elevated in human malignancies. Although the cause(s) of ILK overexpression remain to be fully elucidated, accumulating evidence suggests that its oncogenic capacity derives from its regulation of several downstream targets that provide cells with signals that promote proliferation, survival and migration, supporting the concept that ILK is a relevant therapeutic target in human cancer. Furthermore, a global analysis of the ILK 'interactome' has yielded several novel interactions, and has revealed exciting and unexpected cellular functions of ILK that might have important implications for the development of effective therapeutic agents.