Expression of integrin-linked kinase in lung squamous cell carcinoma and adenocarcinoma: correlation with E-cadherin expression, tumor microvessel density and clinical outcome

Integrin-linked kinase (ILK): the known vs. the unknown and perspectives

Integrin-linked kinase (ILK) is a multifunctional molecular actor in cell-matrix interactions, cell adhesion, and anchorage-dependent cell growth. It combines functions of a signal transductor and a scaffold protein through its interaction with integrins, then facilitating further protein recruitment within the ILK-PINCH-Parvin complex. ILK is involved in crucial cellular processes including proliferation, survival, differentiation, migration, invasion, and angiogenesis, which reflects on systemic changes in the kidney, heart, muscle, skin, and vascular system, also during the embryonal development. Dysfunction of ILK underlies the pathogenesis of various diseases, including the pro-oncogenic activity in tumorigenesis. ILK localizes mostly to the cell membrane and remains an important component of focal adhesion. We do know much about ILK but a lot still remains either uncovered or unclear. Although it was initially classified as a serine/threonine-protein kinase, its catalytical activity is now questioned due to structural and functional issues, leaving the exact molecular mechanism of signal transduction by ILK unsolved. While it is known that the three isoforms of ILK vary in length, the presence of crucial domains, and modification sites, most of the research tends to focus on the main isoform of this protein while the issue of functional differences of ILK2 and ILK3 still awaits clarification. The activity of ILK is regulated on the transcriptional, protein, and post-transcriptional levels. The crucial role of phosphorylation and ubiquitylation has been investigated, but the functions of the vast majority of modifications are still unknown. In the light of all those open issues, here we present an extensive literature survey covering a wide spectrum of latest findings as well as a past-to-present view on controversies regarding ILK, finishing with pointing out some open questions to be resolved by further research.

Clinicopathological significance and prognostic value of E-cadherin expression in non-small cell lung cancer: A protocol for systematic review and meta-analysis

BACKGROUND

E-cadherin, a calcium-dependent cell adhesion molecule, as an important mediator of adhesion and signaling pathway, plays a key role in maintaining tissue integrity. However, the association of E-cadherin expression with clinicopathological features and prognostic value in non-small cell lung cancer (NSCLC) is still controversial. Therefore, the purpose of the study is to explore the clinicopathological features and prognostic value of E-cadherin expression in non-small cell lung cancer by meta-analysis.

METHODS

PubMed, EMBASE, Cochrane Library, and Web of Science were searched to collect the studies about expression of E-cadherin and clinicopathological features and prognosis of non-small cell lung cancer. The last search time was May 2020. Stata 15.0 software was used for statistical analysis.

RESULTS

A total of 35 studies were included, of which the results showed that high expression of E-cadherin compared with its low expression, for overall survival, HR = 0.68 (95% CI:0.64-0.73, P < .05); for disease-free survival or progression-free survival, HR = 0.54 (95% CI: 0.44-0.67); low differentiation of lung cancer compared with moderate and high differentiation, OR = 0.40 (95% CI: 0.27-0.58, P < .05); Advanced lung cancer compared with early stage, OR = 0.54 (95% CI: 0.44-0.66, P < .05); lymph node metastasis compared with non-lymph node metastasis, OR = 0.49 (95% CI: 0.31∼0.77).

CONCLUSION

Low expression of E-cadherin is closely related to poor prognosis of patients with NSCLC, promoting tumor staging and lymph node metastasis, inhibiting tumor differentiation as well.

Mechanism of intrinsic resistance of lung squamous cell carcinoma to epithelial growth factor receptor-tyrosine kinase inhibitors revealed by high-throughput RNA interference screening

Although targeted therapy has achieved a great breakthrough in the treatment of lung adenocarcinoma, there are still no effective targeted drugs for lung squamous cell carcinoma (SqCC). In addition, as immunotherapy can only prolong the overall survival (OS) of lung SqCC by ≤5 months, chemotherapy and radiotherapy are still the main types of therapy for advanced SqCC. The expression level of epithelial growth factor receptor (EGFR) in patients with lung SqCC is higher compared with those with adenocarcinoma, but the former group is intrinsically resistant to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Therefore, if the drug resistance in patients with lung SqCC could be reversed, the majority of patients may benefit from EGFR-TKIs. In the present study, the high-throughput RNA interference technology was used to screen the genes involved in the EGFR-TKI erlotinib resistance of lung SqCCs, and integrin-linked kinase (ILK) was identified to be the most effective. The role of ILK in erlotinib resistance was further studied in cell lines, and the expression of ILK was analyzed in patients with SqCC and adenocarcinoma. Finally, the mechanism of ILK in EGFR-TKIs resistance was analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO) and ingenuity pathway analysis (IPA). The results demonstrated that the ILK gene knockdown could overcome erlotinib resistance by inhibiting cell proliferation, inducing apoptosis and blocking the cell cycle at the G2/M phase. The expression of ILK in patients with SqCC was significantly higher compared with those with adenocarcinoma with sensitizing EGFR mutations. In addition, the cell cycle pathway 'G2/M DNA damage and checkpoint regulation' was identified to be significantly inhibited by ILK knockdown in IPA, KEGG and GO analysis. The results of the present study may improve the understanding of EGFR-TKI resistance in lung SqCCs, thus promoting the development of potential targeted therapies for lung SqCCs.

Overexpression of ILK promotes temozolomide resistance in glioma cells

The present study aimed to investigate whether overexpression of integrin-linked kinase (ILK) affects drug resistance to temozolomide (TMZ) in glioma cells. To do this, a plasmid containing the ILK gene was transfected into the SHG‑44 human glioma cell line, and cells were subsequently cultured in the absence or presence of TMZ. The expression levels of ILK, multidrug resistance‑associated protein (MRP) and multi‑drug resistance protein (MDR) were assessed in these cells. Cell growth and apoptosis were measured by MTT and Hoechst staining, and flow cytometry, respectively. In addition, the expression levels of B‑cell lymphoma 2 (Bcl‑2) and Bcl‑2‑associated x protein (Bax), and caspase‑3 activity, were evaluated. The ILK‑overexpressing SHG‑44 cell was successfully constructed, and demonstrated increased expression levels of ILK, MDR and MRP compared with untransfected cells. Cell growth in the ILK+TMZ group was significantly greater, and the percentage of apoptotic cells in the ILK+TMZ group was significantly reduced, compared with the p enhanced green fluorescent protein (EGFP)‑C1+ TMZ empty vector control group. Expression levels of the anti‑apoptotic protein Bcl‑2 were significantly increased and those of the pro‑apoptotic protein Bax were significantly decreased (P<0.01) in the ILK+TMZ group compared with the pEGFP‑C1+TMZ group. In addition, the activity of caspase‑3 in ILK+TMZ group was significantly decreased compared with the pEGFP‑C1+TMZ group (P<0.01). Overexpression of ILK therefore promoted the proliferation of SHG‑44 human glioma cells, reduced apoptosis and reduced sensitivity to TMZ via decreasing the activity of caspase‑3.

Knockdown of ILK inhibits glioma development via upregulation of E-cadherin and downregulation of cyclin D1

Integrin-linked kinase (ILK) is a highly conserved serine-threonine protein kinase that interacts with cytoplasmic domains of integrin subunits in tumor tissues. However, the relationship between gliomas and ILK is elusive. The present study aimed to investigate the role of ILK in a human glioma cell line (U251). ILK stable expressing vector, U251ILK-PGFP-V-RS-shRNA, was established and named as U251-si. The empty-PGFP-V-RS-shRNA (U251-N) was employed as the control. Quantitative real-time PCR and western blot analysis were used to detect ILK and E-cadherin mRNA and protein expression, respectively. Cell cycle analysis was employed to examine the cell cycle distribution. Cell migration was detected using a wound healing assay, and cell invasion was detected using a Transwell invasion assay. Tumor size and weight were also examined. The results indicated that ILK was expressed at a lower level at both the mRNA and protein levels in the U251-si group compared with the U251-N group (p<0.01). ILK knockdown suppressed cell proliferation of the glioma cells. Knockdown of ILK reduced the migratory and invasive potentials of the glioma cells. Inhibition of ILK expression upregulated E-cadherin and downregulated cyclin D1 in the glioma cells compared to the U251-N group (p<0.05). Knockdown of ILK in the U251 cells attenuated the ability of U251 cells to form tumors in nude mice and impaired glioma cell in vivo tumorigenicity. In conclusion, knockdown of ILK inhibits glioma cell migration, invasion and proliferation through upregulation of E-cadherin and downregulation of cyclin D1. Our results suggest that ILK may serve as a promising therapeutic target for glioma.

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.

Tumour budding is associated with hypoxia at the advancing front of colorectal cancer

AIMS

The tumour budding ability to predict cancer progression is felt to be worthy of investigation with regard to its biological properties. This study was aimed at evaluating the role of hypoxia and microvascularization in the morphogenesis of tumour budding in colorectal carcinoma.

METHODS AND RESULTS

The immunohistochemical expression of hypoxia-inducible factor-1α (HIF-1α) and carbonic anhydrase IX in cancer cells and CD105 in carcinoma-induced microvascularization were assessed in 479 colorectal cancers. Furthermore, MET proto-oncogene, receptor tyrosine kinase (MET) gene amplification was searched using fluorescence in-situ hybridization (FISH). Carbonic anhydrase IX and HIF-1α overall scores differed significantly in low- compared to high-grade tumour budding cancers (P < 0.001), both in pT1 and in pT2-4 tumours. Intratumour analysis of budding foci showed a striking absence of carbonic anhydrase IX immunostain in detaching cells with respect to the surrounding microsectors. The mean microvessel density values were significantly higher in the low- compared to the high-grade tumour budding groups (P < 0.001). A similar copy number of MET gene was detected in the two groups.

CONCLUSIONS

Our study shows that tumour budding is associated with hypoxia induced by hypovascularization at the advancing front of colorectal cancer and that budding cells express a HIF-1α-mediated hypoxic tumour phenotype. MET gene amplification is not related to tumour budding morphogenesis.

Prognostic and clinicopathological significance of downregulated E-cadherin expression in patients with non-small cell lung cancer (NSCLC): a meta-analysis

Background

Many studies have investigated the prognostic role of E-cadherin in patients with NSCLC; however, the result still remains inconclusive. An up-to data system review and meta-analysis was necessary to give a comprehensive evaluation of prognostic role of E-cadherin in NSCLC.

Methods

Eligible studies were searched in Pubmed, Embase and Web of Science databases. The inclusion criteria were studies that assessed the relationship between E-cadherin expression detected by immunohistochemistry (IHC) and the prognosis or clinicopathological features in patients with NSCLC. Subgroup analysis according to race, percentage of reduced/negative E-cadherin expression, histological type, and sample size were also conducted. Odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) were calculated to examine the risk or hazard association.

Results

A total of 29 studies including 4010 patients were qualified for analysis. The analysis suggested that downregulated E-cadherin expression was significant associated with unfavorable overall survival (OS) and disease-free survival/progression-free survival (DFS/PFS) in patients with NSCLC. Subgroup analysis by race, percentage of reduced/negative E-cadherin expression, sample size also found the significant association in OS. When only the stage I NSCLC were considered, downregulated E-cadherin expression still had an unfavorable impact on OS. Additionally, downregulated E-cadherin expression was significantly associated with differentiation grade, lymphnode metastasis, vascular invasion, and TNM stage.

Conclusion

Downregulated E-cadherin expression detected by IHC seems to correlate with tumour progression and could serve as an important prognostic factor in patients with NSCLC.

High expression of integrin-linked kinase predicts aggressiveness and poor prognosis in patients with gastric cancer

Integrin-linked kinase (ILK), an intracellular serine/threonine protein kinase, has been reported to be highly expressed in many human malignancies, including gastric cancer. However, the prognostic significance of ILK expression in gastric cancer remains to be elucidated. In the present study, ILK expression in 95 gastric tumor tissues and 30 adjacent non-cancerous gastric mucosa was evaluated by immunohistochemistry and correlated with clinicopathological characteristics and patients' outcome. The results showed that high ILK expression was observed in 47.4% (45/95) of gastric cancer tissues, but only in 20.0% (6/30) of adjacent gastric mucosa. Clinicopathological analysis indicated that high ILK expression was significantly associated with poor tumor differentiation (P=0.024), advanced TNM stage (P=0.006), tumor invasion (P=0.001), and lymph node metastasis (P=0.014). Kaplan-Meier survival curves demonstrated that patients with high ILK expression had substantially shorter overall survival that those with low ILK expression (P=0.043, log-rank test). Furthermore, Cox multivariate regression analysis identified ILK expression as an independent prognostic factor for overall survival of gastric cancer patients (hazard ratio, 1.95; 95% confidence interval, 1.02-3.13; P=0.026). In conclusion, our data suggest that ILK may contribute to the malignant progression of gastric cancer and serve as a novel prognostic indicator for gastric cancer patients.

Overexpression of integrin-linked kinase (ILK) promotes migration and invasion of colorectal cancer cells by inducing epithelial-mesenchymal transition via NF-κB signaling

Integrin-linked kinase (ILK), a ubiquitously expressed and evolutionally conserved serine/threonine kinase, has been shown to be aberrantly overexpressed and activated in diversified types of human malignancies, including colorectal cancer (CRC). However, the potential role of ILK in cancer cell migration and invasion remains to be elucidated. In this study, we introduced the human ILK gene into a low ILK-expressing human CRC cell line SW480. Cell migration and invasion were evaluated by the wound healing assay and transwell invasion assay, respectively. The epithelial-mesenchymal transition (EMT)-related proteins were detected by Western blot analysis or immunofluorescence. We found that enforced overexpression of ILK in SW480 cells dramatically promoted their migratory and invasive ability in vitro. Furthermore, SW480 cells stably overexpressing ILK underwent EMT, as indicated by mesenchymal morphology, decreased expression of E-cadherin, and increased expression of vimentin, Snail, and Slug. Finally, the nuclear factor (NF)-κB inhibitor BAY 11-7028 or NF-κB p65 small interfering RNA significantly restored the reduced E-cadherin level in ILK-overexpressing cells, suggesting that ILK-mediated down-regulation of E-cadherin is dependent on NF-κB activation. Overall, our study demonstrates a pivotal role of ILK in EMT and metastasis, and suggests novel therapeutic opportunities for the treatment of CRC.

PPARβ/δ promotes HRAS-induced senescence and tumor suppression by potentiating p-ERK and repressing p-AKT signaling

Peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) inhibits skin tumorigenesis through mechanisms that may be dependent on HRAS signaling. The present study examined the hypothesis that PPARβ/δ promotes HRAS-induced senescence resulting in suppression of tumorigenesis. PPARβ/δ expression increased p-ERK and decreased p-AKT activity. Increased p-ERK activity results from the dampened HRAS-induced negative feedback response mediated in part through transcriptional upregulation of RAS guanyl-releasing protein 1 (RASGRP1) by PPARβ/δ. Decreased p-AKT activity results from repression of integrin-linked kinase (ILK) and phosphoinositide-dependent protein kinase-1 (PDPK1) expression. Decreased p-AKT activity in turn promotes cellular senescence through upregulation of p53 and p27 expression. Both over-expression of RASGRP1 and shRNA-mediated knockdown of ILK partially restore cellular senescence in Pparβ/δ-null cells. Higher PPARβ/δ expression is also correlated with increased senescence observed in human benign neurofibromas and colon adenoma lesions in vivo. These results demonstrate that PPARβ/δ promotes senescence to inhibit tumorigenesis and provide new mechanistic insights into HRAS-induced cellular senescence.

Overexpression of integrin-linked kinase (ILK) promotes glioma cell invasion and migration and down-regulates E-cadherin via the NF-κB pathway

Integrin-linked kinase (ILK) is a ubiquitously expressed serine/threonine protein kinase that has been implicated in cancer development, progression and metastasis. The aim of the present study was to characterize the role of ILK in glioma cell invasion and migration. We generated a recombinant eukaryotic expression vector containing the human ILK gene and transfected it into human glioma SHG-44 cells. Real-time PCR and western blot analysis were used to identify the stable transformants. The wound healing and Transwell invasion assays showed that ectopic overexpression of ILK in SHG-44 cells significantly promoted their migration and invasion capabilities in culture. This was accompanied by a decrease in expression of E-cadherin and an increase in expression of Snail and Slug. Moreover, the decrease in E-cadherin expression induced by ILK overexpression was greatly restored by the nuclear factor-κB (NF-κB) inhibitor BAY 11-7028 or small interfering RNA targeting NF-κB p65, indicating an involvement of NF-κB in ILK-induced down-regulation of E-cadherin. In conclusion, our data underscore a novel role for ILK in glioma invasion and metastasis processes, implicating potential for therapeutic interference.

Focal adhesion complex proteins in epidermis and squamous cell carcinoma

Focal adhesions (FAs) are large, integrin-containing, multi-protein assemblies spanning the plasma membrane that link the cellular cytoskeleton to surrounding extracellular matrix. They play critical roles in adhesion and cell signaling and are major regulators of epithelial homeostasis, tissue response to injury, and tumorigenesis. Most integrin subunits and their associated FA proteins are expressed in skin, and murine genetic models have provided insight into the functional roles of FAs in normal and neoplastic epidermis. Here, we discuss the roles of these proteins in normal epidermal proliferation, adhesion, wound healing, and cancer. While many downstream signaling mechanisms remain unclear, the critically important roles of FAs are highlighted by the development of therapeutics targeting FAs for human cancer.

Clinical significance of E-cadherin, β-catenin, vimentin and S100A4 expression in completely resected squamous cell lung carcinoma

OBJECTIVE

The aim of this study was to evaluate the prognostic value of E-cadherin, β-catenin, vimentin and S100A4 expression in a cohort of squamous cell lung carcinoma (SqCC) patients.

METHODS

Tumours from 204 patients with surgically resected SqCC were used for the immunohistochemical analyses of E-cadherin, β-catenin, vimentin and S100A4 expression. Correlations between the expression of these markers and clinicopathological parameters were analysed using the χ(2) test. The prognostic value of these markers was evaluated using univariate Kaplan-Meier survival analyses and multivariate Cox proportional hazards model analyses.

RESULTS

Significant associations between E-cadherin expression and T stage (p=0.040), histological differentiation (p=0.005), lymph node metastasis (p<0.001), and recurrence (p<0.001) were identified. Decreased β-catenin expression was significantly correlated with T stage (p=0.003) and lymph node metastasis (p=0.010). Vimentin expression was associated with histological differentiation (p=0.017) and lymph node metastasis (p=0.001). Moreover, significant correlations were observed between S100A4 expression and lymph node metastasis (p=0.020) and recurrence (p<0.001). In the univariate analyses, high E-cadherin expression was a positive indicator for overall survival (OS) (p<0.001) and disease-free survival (DFS) (p<0.001), whereas high S100A4 or vimentin expression were negative indicators for OS (p<0.001 and p=0.010, respectively) and DFS (p<0.001 and p=0.006, respectively). In the multivariate analyses, E-cadherin and S100A4 expression were independent prognostic factors for OS (HR 0.697, 95% CI 0.524 to 0.926, p=0.013, and HR 1.508, 95% CI 1.122 to 2.027, p=0.007, respectively) and DFS (HR 0.634, 95% CI 0.471 to 0.852, p=0.003, and HR 1.490, 95% CI 1.101 to 2.015, p=0.010, respectively).

CONCLUSIONS

Effective analysis of E-cadherin and S100A4 expression may allow for the identification of patients who are at a high risk of recurrence and poor prognosis in SqCC.

Expression of integrin-linked kinase in adenoid cystic carcinoma of salivary glands correlates with epithelial-mesenchymal transition markers and tumor progression

Integrin-linked kinase (ILK) plays a key role in cell-excellular matrix interactions mediated by integrins and several growth factors, regulating cell proliferation, apoptosis, differentiation, and migration. It has also been implicated in the development and progression in several malignancies involving epithelial to mesenchymal transition (EMT). However, the correlations between ILK and EMT markers and the progression of salivary adenoid cystic carcinoma (SACC) have not been well elucidated. Here, by immunohistochemistry, we studied the expression of ILK, Snail, E-cadherin, and N-cadherin in 94 SACC specimens and analyzed their correlations with clinicopathologic characteristics. Positive expression of ILK protein was detected in 76.6 % of the tumors. Increased expression of ILK and Snail and decreased E-cadherin expression correlated strongly with tumor solid type (P = 0.017, P = 0.008, and P = 0.038, respectively), advanced TNM stage (P = 0.021, P = 0.034, and P = 0.009, respectively), and increased risk of recurrence (P = 0.023, P = 0.011, and P = 0.039, respectively) and distant metastasis (P < 0.001, P < 0.001, and P = 0.001, respectively). Moreover, up-regulation of Snail and N-cadherin and down-regulation of E-cadherin correlated significantly with ILK over-expression (P < 0.001, P = 0.001, and P < 0.001, respectively) and a neural-invasive phenotype (P = 0.017, P = 0.002, and P < 0.001, respectively). Taken together, our results suggest that ILK may have an important role in progression and metastasis of SACC, possibly through EMT involving up-regulation of Snail and consequent aberrant expression of E-cadherin and N-cadherin. ILK should be considered as a potential therapeutic molecular target for patients with SACC.

Overexpression of integrin-linked kinase correlates with malignant phenotype in non-small cell lung cancer and promotes lung cancer cell invasion and migration via regulating epithelial-mesenchymal transition (EMT)-related genes

Integrin-linked kinase (ILK), a member of the serine/threonine kinases, has been implicated in oncogenesis and progression of human cancers. The aim of this study was to characterize the role of ILK in lung cancer aggressiveness and the underlying molecular mechanisms. ILK protein expression was assessed by immunohistochemistry in a cohort of non-small cell lung cancer (NSCLC) patients, and a series of in vitro assays was conducted to elucidate the function of ILK in lung cancer. Overexpression of ILK protein was detected in 30.6% (33/108) of primary NSCLC tissues and correlated with the TNM stage (P=0.001) and lymph node metastasis (P=0.033). Ectopic overexpression of ILK in lung cancer cells promoted cell migration and invasion in vitro, and led to the acquisition of epithelial-mesenchymal transition (EMT) phenotype, as evidenced by the spindle-like morphology, down-regulation of E-cadherin, and up-regulation of vimentin, fibronectin, Snail and Slug. In addition, the down-regulation of E-cadherin induced by ILK was significantly reversed by nuclear factor-κB (NF-κB) inhibitor BAY 11-7028 and small interfering RNA (siRNA) targeting NF-κB p65, suggesting a role of the NF-κB signaling pathway in ILK-induced EMT. Overall, our results suggest that ILK promotes lung cancer cell migration and invasion through the induction of EMT process.

Quantitative chemical proteomics profiling differentiates erlotinib from gefitinib in EGFR wild-type non-small cell lung carcinoma cell lines

Although both erlotinib and gefitinib target the EGF receptor (EGFR), erlotinib is effective in patients with EGFR wild-type or mutated tumors, whereas gefitinib is only beneficial for patients with activating mutations. To determine whether these differences in clinical outcomes can be attributed to their respective protein interaction profiles, a label-free, quantitative chemical proteomics study was conducted. Using this method, 24 proteins were highlighted in the binding profiles of erlotinib and gefitinib. Unlike gefinitib, erlotinib displaced the ternary complex formed by integrin-linked kinase (ILK), α-parvin, and PINCH (IPP). The docking of erlotinib in the three-dimensional structure of ILK showed that erlotinib has the ability to bind to the ATP-binding site, whereas gefitinib is unlikely to bind with high affinity. As the IPP complex has been shown to be involved in epithelial-to-mesenchymal transition (EMT) and erlotinib sensitivity has been correlated with EMT status, we used a cellular model of inducible transition and observed that erlotinib prevented EMT in a more efficient way than gefitinib by acting on E-cadherin expression as well as on IPP levels. A retrospective analysis of the MERIT trial indicated that, besides a high level of E-cadherin, a low level of ILK could be linked to clinical benefit with erlotinib. In conclusion, we propose that, in an EGFR wild-type context, erlotinib may have a complementary mode of action by inhibiting IPP complex activities, resulting in the slowing down of the metastatic process of epithelial tumors.

Overexpression of integrin-linked kinase promotes lung cancer cell migration and invasion via NF-κB-mediated upregulation of matrix metalloproteinase-9

Integrin-linked kinase (ILK) is a highly conserved serine-threonine protein kinase which has been implicated in the regulation of various cellular processes. Previously, we have demonstrated that overexpression of ILK correlates with malignant phenotype in non-small cell lung cancer. Furthermore, forced overexpression of ILK promotes lung cancer cell invasion and migration. However, the molecular mechanisms by which ILK enhances the invasive phenotype of lung cancer cells are still not fully understood. In the present study, we found that overexpression of ILK stimulated matrix metalloproteinase-9 (MMP-9) expression and activity in lung cancer cells. ILK-induced cell migration and invasion were significantly inhibited by MMP inhibitor doxycycline as well as by anti-MMP-9 neutralizing antibody. In addition, overexpression of ILK induced phosphorylation and nuclear translocation of nuclear factor-κB (NF-κB) subunit p65. Finally, upregulation of MMP-9 was severely abolished by either BAY 11-7028, a specific NF-κB inhibitor, or small interfering RNA targeted to NF-κB p65 in ILK overexpression cells. Taken together, these findings suggest that ILK promotes lung cancer cell migration and invasion via NF-κB-mediated upregulation of MMP-9.

Overexpression of integrin-linked kinase (ILK) is associated with tumor progression and an unfavorable prognosis in patients with colorectal cancer

Integrin-linked kinase (ILK), an intracellular serine-threonine kinase, has been reported to be overexpressed in multiple types of human malignancies, including colorectal cancer (CRC). The prognostic value of ILK in CRC, however, remains unknown. In the present study, expression of ILK in 25 paired primary CRC samples and adjacent noncancerous tissues were quantified using real-time PCR and Western blotting. ILK protein expression was analyzed in 102 archived, paraffin-embedded CRC samples using immunohistochemistry. The correlation between ILK expression and clinicopathological factors was evaluated by the χ(2) test. Patients' overall survival was analyzed by Kaplan-Meier method. We found that both ILK mRNA and protein expression levels were significantly up-regulated in primary CRC samples compared with their corresponding normal tissues. Immunohistochemical analysis revealed relative high expression of ILK in 43 of 102 (42.2 %) primary CRC samples. Statistical analysis showed a significant correlation of ILK expression with tumor differentiation, lymph node metastasis, tumor invasion, and tumor-node-metastasis stage. Patients with tumors displaying high-level ILK expression showed significantly shorter overall survival (P = 0.028, log-rank test). More importantly, multivariate analysis indicated that high ILK protein expression was an independent prognostic factor for CRC patients (P = 0.026). Taken together, our data suggest that ILK overexpression is associated with tumor progression and a poor prognosis in CRC patients and may represent a novel potential prognostic marker for patients with CRC.

α-Catulin drives metastasis by activating ILK and driving an αvβ3 integrin signaling axis

α-Catulin is an oncoprotein that helps sustain proliferation by preventing cellular senescence. Here, we report that α-catulin also drives malignant invasion and metastasis. α-Catulin was upregulated in highly invasive non-small cell lung cancer (NSCLC) cell lines, where its ectopic expression or short-hairpin RNA-mediated attenuation enhanced or limited invasion or metastasis, respectively. α-Catulin interacted with integrin-linked kinase (ILK), a serine/threonine protein kinase implicated in cancer cell proliferation, antiapoptosis, invasion, and angiogenesis. Attenuation of ILK or α-catulin reciprocally blocked cell migration and invasion induced by the other protein. Mechanistic investigations revealed that α-catulin activated Akt-NF-κB signaling downstream of ILK, which in turn led to increased expression of fibronectin and integrin αvβ3. Pharmacologic or antibody-mediated blockade of NF-κB or αvβ3 was sufficient to inhibit α-catulin-induced cell migration and invasion. Clinically, high levels of expression of α-catulin and ILK were associated with poor overall survival in patients with NSCLC. Taken together, our study shows that α-catulin plays a critical role in cancer metastasis by activating the ILK-mediated Akt-NF-κB-αvβ3 signaling axis.

The role of pseudokinases in cancer

Kinases play a critical role in regulating many cellular functions including development, differentiation and proliferation. To date, over 518 proteins with kinase activity, comprising ~2-3% of total cellular proteins, have been identified from within the human kinome. Interestingly, approximately 10% of kinases are categorised as pseudokinases since they lack one or more conserved catalytic residues within their kinase domain and were originally thought to have no enzymatic activity. Recently, there has been strong evidence to suggest that some pseudokinsases can not only function as scaffold proteins, but may also possess kinase activity leading to modulation of cell signalling pathways. Altered activity of these pseudokinases can result in impaired cellular function, particularly in malignancies. In this review we are discussing recent evidence that apart from a scaffolding role, pseudokinases also orchestrate cellular processes as active kinases per se in signalling pathways of malignant cells.

Over-expression of integrin-linked kinase correlates with aberrant expression of Snail, E-cadherin and N-cadherin in oral squamous cell carcinoma: implications in tumor progression and metastasis

Integrin-linked kinase (ILK), an intracellular protein with serine/threonine protein kinase activities, plays a key role in integrin mediated cell-excellular matrix interactions, regulating cell proliferation, apoptosis, differentiation, and migration. ILK has been implicated in the development and progression in several malignancies. However, the role of ILK and ILK-mediated epithelial-mensenchymal transition (EMT) in the progression of oral squamous cell carcinoma (OSCC) has not been well understood. Here, by immunohistochemistry, we studied the expression of ILK, Snail, E-cadherin and N-cadherin in 98 primary OSCC specimens and analyzed their correlations with clinicopathologic profiles and clinical outcome. We also investigated the expression of ILK in 42 corresponding lymph node metastases. Positive expression of ILK protein was detected in 87.8 % of the primary tumors and 100 % of metastatic lesions. Increased ILK expression was correlated strongly with enhanced tumor invasion, higher tumor grade, advanced clinical stage, positive lymph node status and increased risk of recurrence. Higher ILK expression was also observed in lymph node metastases in comparison with the corresponding primary tumor. Moreover, up-regulation of Snail and N-cadherin and down-regulation of E-cadherin correlated significantly with both ILK over-expression and tumor invasion. Patients with higher ILK expression exhibited shorter disease-free survival while those with absent E-cadherin expression exhibited shorter overall and disease-free survival. Taken together, our results suggest that ILK may have an important role in progression and metastasis of OSCC, possibly through EMT involving up-regulation of Snail and consequent aberrant expression of E-cadherin and N-cadherin. ILK should be considered as a critical prognostic indicator for patients with OSCC.

Small interfering RNA targeting integrin-linked kinase inhibited the growth and induced apoptosis in human bladder cancer cells

Integrin-linked kinase (ILK), an intracellular serine/threonine kinase, is implicated in cell growth and survival, cell-cycle progression, tumor angiogenesis, and cell apoptosis. Recent studies showed that the expression and activity of ILK increased significantly in many types of solid tumors. However, the exact molecular mechanism of ILK underlie tumor has not been fully ascertained. The purpose of our study was to determine whether knockdown of ILK would inhibit cell growth and induce apoptosis in bladder cancer cells using a plasmid vector based small interfering RNA (siRNA). The experiments showed that knockdown of ILK could remarkably inhibit cell proliferation and growth, regulate cell cycle and induce apoptosis of bladder cancer BIU-87 and EJ cells. We demonstrated that knockdown of ILK inhibited phosphorylation of downstream signaling targets protein kinase B/Akt, glycogen synthase kinase 3-beta (GSK-3β), and reduced expression of β-catenin in BIU-87 as well as EJ cells by Western blot and Immunofluorescence analysis. In addition, down-regulation of ILK also could increase expression of Ribonuclease inhibitor (RI), an important acidic cytoplasmic protein with many functions. BALB/C nude mice injected with the BIU-87 cells transfected ILK siRNA showed a significant inhibition of the tumor growth with lighter tumor weight, lower microvessels density and higher apoptosis rate than those in the other two control groups. In conclusion, these results suggest that ILK might be involved in the development of bladder cancer, and could be served as a novel potential therapy target for human bladder cancer. Our study may be of biological and clinical importance.