Mechanisms and consequences of constitutive activation of integrin-linked kinase in acute myeloid leukemia

Integrin linked kinase and threonine tyrosine kinase modulate TCR signaling

T cell activation is critical for adaptive immunity, helping to protect the body from infection and tumors. A key step in this activation is signal transduction downstream of the T cell antigen receptor. This signaling involves several steps, with early ones occurring at the plasma membrane and others that occur later, after TCR internalization. The late steps in TCR signaling remain poorly understood. Since the TCR can signal after its internalization, we postulated that kinases abundantly expressed in T cells may regulate TCR signaling. This study focuses on two such enzymes: integrin-linked kinase (ILKs) and threonine-tyrosine kinase (TTKs), whose involvement in TCR signaling has not been previously studied. Using specific depletion of TTK and ILK by lentiviral shRNA, we show that in the absence of ILK and TTK, the early steps of TCR signaling are strongly enhanced, while IL-2 production by activated T cells is strongly decreased. These findings are relevant because TTK and ILK are both important targets in oncology, and our results show that their inhibition affects the activation of T cells, which play an essential role in anti-tumor defense.

Proteomic Comparison of Acute Myeloid Leukemia Cells and Normal CD34+ Bone Marrow Cells: Studies of Leukemia Cell Differentiation and Regulation of Iron Metabolism/Ferroptosis

Acute myeloid leukemia (AML) is an aggressive bone marrow malignancy that can be cured only by intensive chemotherapy possibly combined with allogeneic stem cell transplantation. We compared the pretreatment proteomic profiles of AML cells derived from 50 patients at the time of first diagnosis with normal CD34+ bone marrow cells. A comparison based on all AML and CD34+ normal cell populations identified 121 differentially abundant proteins that showed at least 2-fold differences, and these proteins included several markers of neutrophil differentiation (e.g., TLR2, the integrins ITGM and ITGX, and downstream mediators including RHO GTPase, S100A8, S100A9, S100A22). However, the expression of these 121 proteins varied between patients, and a subset of 28 patients was characterized by increased long-term AML-free survival, signs of myeloid AML cell differentiation, and favorable genetic abnormalities. These two main patient subsets (28 with differentiation versus 22 with fewer signs of differentiation) also differed with regard to the phosphorylation of 16 differentially abundant proteins. Furthermore, we also classified our patients based on their expression of 16 proteins involved in the regulation of iron metabolism/ferroptosis and showing differential expression when comparing AML cells and normal CD34+ cells. Among the 22 patients with less favorable prognosis, we could then identify a genetically heterogeneous subset characterized by adverse prognosis (i.e., death from primary resistance/relapse) and an iron metabolism/ferroptosis protein profile showing similarities with normal CD34+ cells. We conclude that proteomic profiles differ between AML and normal CD34+ cells; especially, proteomic differences reflecting differentiation and regulation of iron metabolism/ferroptosis are associated with risk of relapse after intensive conventional therapy.

Targeting integrins in drug-resistant acute myeloid leukaemia

Acute myeloid leukaemia (AML) continues to have a poor prognosis, warranting new therapeutic strategies. The bone marrow (BM) microenvironment consists of niches that interact with not only normal haematopoietic stem cells (HSC) but also leukaemia cells like AML. There are many adhesion molecules in the BM microenvironment; therein, integrins have been of central interest. AML cells express integrins that bind to ligands in the microenvironment, enabling adhesion of leukaemia cells in the microenvironment, thereby initiating intracellular signalling pathways that are associated with cell migration, cell proliferation, survival, and drug resistance that has been described to mediate cell adhesion-mediated drug resistance (CAM-DR). Identifying and targeting integrins in AML to interrupt interactions with the microenvironment have been pursued as a strategy to overcome CAM-DR. Here, we focus on the BM microenvironment and review the role of integrins in CAM-DR of AML and discuss integrin-targeting strategies. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc.

Integrin-linked kinase expression in myeloid cells promotes colon tumorigenesis

Colorectal cancer (CRC) is one of the most common forms of cancer worldwide and treatment options for advanced CRC, which has a low 5-year survival rate, remain limited. Integrin-linked kinase (ILK), a multifunctional, scaffolding, pseudo-kinase regulating many integrin-mediated cellular processes, is highly expressed in many cancers. However, the role of ILK in cancer progression is yet to be fully understood. We have previously uncovered a pro-inflammatory role for myeloid-specific ILK in dextran sodium sulfate (DSS)-induced colitis. To establish a correlation between chronic intestinal inflammation and colorectal cancer (CRC), we investigated the role of myeloid-ILK in mouse models of CRC. When myeloid-ILK deficient mice along with the WT control mice were subjected to colitis-associated and APCmin/+-driven CRC, tumour burden was reduced by myeloid-ILK deficiency in both models. The tumour-promoting phenotype of macrophages, M2 polarization, in vitro was impaired by the ILK deficiency and the number of M2-specific marker CD206-expressing tumour-associated macrophages (TAMs) in vivo were significantly diminished in myeloid-ILK deficient mice. Myeloid-ILK deficient mice showed enhanced tumour infiltration of CD8+ T cells and reduced tumour infiltration of FOXP3+ T cells in colitis-associated and APCmin/+-driven CRC, respectively, with an overall elevated CD8+/FOXP3+ ratio suggesting an anti-tumour immune phenotypes. In patient CRC tissue microarrays we observed elevated ILK+ myeloid (ILK+ CD11b+) cells in tumour sections compared to adjacent normal tissues, suggesting a conserved role for myeloid-ILK in CRC development in both human and animal models. This study identifies myeloid-specific ILK expression as novel driver of CRC, which could be targeted as a potential therapeutic option for advanced disease.

Theragnostic strategies harnessing the self-renewal pathways of stem-like cells in the acute myeloid leukemia

Acute myelogenous leukemia (AML) is a genetically heterogeneous and aggressive cancer of the Hematopoietic Stem/progenitor cells. It is distinguished by the uncontrollable clonal growth of malignant myeloid stem cells in the bone marrow, venous blood, and other body tissues. AML is the most predominant of leukemias occurring in adults (25%) and children (15-20%). The relapse after chemotherapy is a major concern in the treatment of AML. The overall 5-year survival rate in young AML patients is about 40-45% whereas in the elderly patients it is less than 10%. Leukemia stem-like cells (LSCs) having the ability to self-renew indefinitely, repopulate and persist longer in the G0/G1 phase play a crucial role in the AML relapse and refractoriness to chemotherapy. Hence, novel treatment strategies and diagnostic biomarkers targeting LSCs are being increasingly investigated. Through this review, we have explored the signaling modulations in the LSCs as the theragnostic targets. The significance of the self-renewal pathways in overcoming the treatment challenges in AML has been highlighted.

New Perspectives on the Role of Integrin-Linked Kinase (ILK) Signaling in Cancer Metastasis

Simple Summary

Today, the vast majority of deaths from cancer are due to cancer metastasis. Metastasis requires that cancer cells escape from the initial tumor, travel through blood vessels, and form new tumors in distant host tissues. Integrin-linked kinase (ILK) is overexpressed by many types of cancer cells and provides both structural and signaling functions that are important for successful metastasis. Here, we discuss recent findings that show how ILK is involved in promoting physical changes important for cell motility and invasion, and how ILK relays signals to other machinery components during metastasis, including interactions with components of the immune system and communication between cancer cells and normal cells, to affect the process of metastasis. We also discuss the contribution of ILK to therapeutic resistance and examine efforts to target ILK for the treatment of metastatic disease.

Abstract

Cancer metastasis is a major barrier to the long-term survival of cancer patients. In cancer cells, integrin engagement downstream of cell-extracellular matrix (ECM) interactions results in the recruitment of cytoskeletal and signaling molecules to form multi-protein complexes to promote processes critical for metastasis. One of the major functional components of these complexes is Integrin Linked Kinase (ILK). Here, we discuss recent advances in our understanding of the importance of ILK as a signaling effector in processes linked to tumor progression and metastasis. New mechanistic insights as to the role of ILK in cellular plasticity, epithelial mesenchymal transition (EMT), migration, and invasion, including the impact of ILK on the formation of invadopodia, filopodia-like protrusions (FLPs), and Neutrophil Extracellular Trap (NET)-induced motility are highlighted. Recent findings detailing the contribution of ILK to therapeutic resistance and the importance of ILK as a potentially therapeutically tractable vulnerability in both solid tumors and hematologic malignancies are discussed. Indeed, pharmacologic inhibition of ILK activity using specific small molecule inhibitors is effective in curtailing the contribution of ILK to these processes, potentially offering a novel therapeutic avenue for inhibiting critical steps in the metastatic cascade leading to reduced drug resistance and increased therapeutic efficacy.

Astragalus Polysaccharide Reduces Blood Pressure, Renal Damage, and Dysfunction Through the TGF-β1-ILK Pathway

Background:Astragalus polysaccharide extract (APS) has been shown to exhibit antioxidant and anti-inflammatory potential in the treatment of several diseases. However, whether APS could protect against renal damage in hypertensive mice is unknown.

Methods: Hematoxylin and eosin staining, immunohistochemistry, real-time polymerase chain reaction, and Western blotting were used to investigate the effect of APS on the renal damage in deoxycorticosterone acetate- (DOCA) salt- and angiotensin II- (Ang II-) induced hypertensive mice and to elucidate the underlying mechanisms.

Results: Our data demonstrated that APS significantly reduced blood pressure in DOCA-salt- and Ang II-treated mice. Furthermore, APS reduced the inflammatory response and renal fibrosis, thereby improving renal function. Furthermore, the levels of serum creatinine, urea nitrogen, and uric acid increased in DOCA-salt-treated mice, alleviated by APS administration. At the molecular level, DOCA-salt and Ang II increased the mRNA levels of IL-1β, IL-6, α-SMA, collagen I, and collagen III, while APS significantly inhibited these effects. APS inhibited the TGF-β1/ILK signaling pathway, which was activated in hypertensive mice due to the administration of DOCA-salt.

Conclusion: Our results suggest that APS plays a beneficial role in improving renal dysfunction in hypertensive mice.

Downstream Effectors of ILK in Cisplatin-Resistant Ovarian Cancer

Despite good responses to first-line treatment with platinum-based combination chemotherapy, most ovarian cancer patients will relapse and eventually develop platinum-resistant disease with poor prognosis. Although reports suggest that integrin-linked kinase (ILK) is a potential target for ovarian cancer treatment, identification of ILK downstream effectors has not been fully explored. The purpose of this study was to investigate the molecular and biological effects of targeting ILK in cisplatin-resistant ovarian cancer. Western blot analysis showed that phosphorylation levels of ILK were higher in cisplatin-resistant compared with cisplatin-sensitive ovarian cancer cells. Further immunohistochemical analysis of ovarian cancer patient samples showed a significant increase in phosphorylated ILK levels in the tumor tissue when compared to normal ovarian epithelium. Targeting ILK by small-interfering RNA (siRNA) treatment reduced cisplatin-resistant cell growth and invasion ability, and increased apoptosis. Differential gene expression analysis by RNA sequencing (RNA-Seq) upon ILK-siRNA transfection followed by Ingenuity Pathway Analysis (IPA) and survival analysis using the Kaplan-Meier plotter database identified multiple target genes involved in cell growth, apoptosis, invasion, and metastasis, including several non-coding RNAs. Taken together, results from this study support ILK as an attractive target for ovarian cancer and provide potential ILK downstream effectors with prognostic and therapeutic value.

Integrin-linked kinase (ILK) and src homology 2 domain-containing phosphatase 2 (SHP2): Novel targets in EGFR-mutation positive non-small cell lung cancer (NSCLC)

BACKGROUND

The activation of multiple signaling pathways jeopardizes the clinical efficacy of EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutation positive non-small cell lung cancer (NSCLC). Integrin-linked kinase (ILK) regulates the interactions between tumor cells and extracellular environment to activate signaling pathways and promote cell proliferation, migration, and epithelial-mesenchymal transition. Src homology 2 domain-containing phosphatase 2 (SHP2) is essential for receptor tyrosine kinase signaling and mitogen-activated protein kinase (MAPK) pathway activation.

METHODS

We analyzed tumor ILK, β-receptor subunit glycoprotein 130 (gp130), SHP2, and stromal hepatocyte growth factor (HGF) and interleukin-6 (IL-6) mRNA expression in baseline tumor specimens of advanced EGFR-mutation positive NSCLC patients treated with EGFR TKIs.

RESULTS

ILK, when highly expressed, was an independent poor prognostic factor for the progression-free survival of the patients, both in the univariate (hazard ratio [HR for disease progression, 2.49; 95% CI, 1.37-4.52; P = .0020]) and in the multivariate (HR 3.74; 95% CI, 1.33-10.56; P = .0126) Cox regression model. Patients with high SHP2 expression had an almost 13-month shorter progression-free survival (P = .0094) and an 18-month shorter overall survival (P = .0182) in comparison to those with low SHP2 mRNA expression.

INTERPRETATION

The levels of ILK and SHP2 could be predictive for upfront combinatory therapy of EGFR TKIs plus SHP2 or ILK inhibitors. FUND: A grant from La Caixa Foundation, an Instituto de Salud Carlos III grant (RESPONSE, PIE16/00011), an Instituto de Salud Carlos III grant (PI14/01678), a Marie Skłodowska-Curie Innovative Training Networks European Grant (ELBA No 765492) and a Spanish Association Against Cancer (AECC) grant (PROYE18012ROSE).