Integrin-linked kinase in gastric cancer cell attachment, invasion and tumor growth

Circ_PABPC1 promotes the malignancy of gastric cancer through interacting with ILK to activate NF-κB pathway

BACKGROUND

Gastric cancer (GC) is a common cancer type with both high incidence and mortality. Recent studies have revealed an important role of circRNA in the development of GC. However, more experiments are needed to reveal the precise molecular mechanisms of circRNA in GC development.

METHODS

Bioinformatics analysis was conducted to predict the potential role of circ_PABPC1 in GC and the target proteins of circ_PABPC1. Quantitative RT-PCR, Western blot and immunohistochemistry assays were conducted to detect the levels of circ_PABPC1, NF-κB p65, NF-κB p65 (Ser536) and ILK. MTT, Edu staining, cell scratch-wound and trans-well assays were carried out to detect cell proliferation, migration and invasion. The interaction between ILK and circ_PABPC1 was confirmed by RNA immunoprecipitation (RIP), RNA pull-down and fluorescence in situ hybridization assays. Genetically modified GC cells were injected into mice to evaluate the tumor growth performance.

RESULTS

This study found that the high expression of circ_PABPC1 was associated with a poor prognosis of GC. The up-regulation of circ_PABPC1 promoted the proliferation, migration and invasion of GC cells. Circ_PABPC1 bound to ILK protein, thereby preventing the degradation of ILK. ILK mediated the effect of circ_PABPC1 on GC cells through activating NF-κB.

CONCLUSION

circ_PABPC1 promotes the malignancy of GC cells through binding to ILK to activate NF-κB signaling pathway.

Comparison of ILK and ERP29 expressions in benign and malignant pancreatic lesions and their clinicopathological significances in pancreatic ductal adenocarcinomas

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor of the pancreas with poor prognosis. The lack of understanding of the molecular mechanisms of PDAC and biomarkers for early diagnosis might be two of the reasons for the poor prognosis of PDAC.

MATERIALS AND METHODS

ILK and ERP29 protein expressions in PDAC, peritumoral tissues, benign pancreatic lesions, and normal pancreatic tissues were measured by immunohistochemistry and the clinical and pathological significances of ILK and ERP29 in PDAC were analyzed.

RESULTS

The percentages of positive ILK and negative ERP29 expressions were significantly higher in PDAC tumors than in peritumoral tissues, benign pancreatic tissues, and normal pancreatic tissues (P < 0.01). Benign pancreatic lesions with positive ILK and negative ERP29 expressions exhibited dysplasia or intraepithelial neoplasia. The percentage of cases with positive ILK and negative ERP29 expressions was significantly lower in PDAC patients without lymph node metastasis and invasion, and having TNM stage I/II disease than in patients with lymph node metastasis, invasion, and TNM stage III/IV disease (P < 0.05 or P < 0.01). Kaplan-Meier survival analysis showed that positive ILK and negative ERP29 expressions were significantly associated with survival in PDAC patients (P < 0.001). Cox multivariate analysis revealed that positive ILK and negative ERP29 expressions were independent poor prognosis factors in PDAC patients.

CONCLUSIONS

Positive ILK and negative ERP29 expressions are associated with the progression of PDAC and poor prognosis in patients with PDAC.

Effects of lentivirus-mediated shRNA targeting integrin-linked kinase on oral squamous cell carcinoma in vitro and in vivo

Integrin-linked kinase (ILK), a highly conserved intracellular protein of serine/threonine protein kinase activities, which is associated with the integrin and growth factor receptor signaling pathway, is involved in the regulation of cell proliferation, apoptosis, differentiation, migration and epithelial-mesenchymal transition (EMT). Findings of a previous study showed that ILK overexpression was strongly correlated with a more aggressive tumor phenotype, recurrence and poor survival for oral squamous cell carcinoma (OSCC) patients, as well as some EMT markers. In order to investigate the underlying mechanisms involved, a lentivirus-mediated short hairpin RNA (shRNA) was employed to downregulate ILK. The results showed that the knockdown of ILK inhibited cell growth, adhesion and invasion ability in vitro, and OSCC cells deficient of ILK were blocked in the S phase and underwent apoptosis. Additionally, ILK shRNA inhibited EMT by impairing the expression of Snail, Slug and Twist2 and enhacning E-cadherin expression. ILK shRNA suppressed the phosphorylation of downstream signaling targets Akt and GSk-3β. In addition, the knockdown of ILK inhibited tumor growth, invasion and metastasis of xenograft tumors in vivo. These results suggested that ILK is a promising therapeutic target for the treatment of OSCC.

Role of integrin-linked kinase in drug resistance of lung cancer

Objective

The objective of the present investigation was to investigate the role of integrin-linked kinase (ILK) in the gemcitabine-resistant lung cancer cell line A549 and explore the underlying mechanism.

Materials and methods

Gemcitabine-resistant A549 (A549/GemR) cell line was established by pulse-exposed to moderate concentration of gemcitabine (Gem), and the drug resistant index was measured by MTT assay. Expression of ILK in A549/GemR cell line was detected by Western blot and real-time PCR. An ILK gene-silencing cell line was constructed using lentivirus-coated ILK shRNA. MTT assay was used to detect the drug sensitivity of the A549/GemR cell line to Gem after the ILK gene silencing. Western blot was used to measure the expression of E-cadherin, fibronectin, and MRP1 (multidrug resistance-associated protein 1) after silencing the ILK gene.

Result

The drug resistance index of A549/GemR was 13.5, and the messenger RNA and protein level of ILK was increased in A549/GemR. IC₅₀ (half maximal inhibitory concentration) decreased from 14.69 to 4.13 mg/L when ILK was knocked down in A549/GemR. The expression of fibronectin and MRP1 was upregulated and E-cadherin expression was downregulated in A549/GemR, and these changes were reversed after ILK was knocked down.

Conclusion

ILK was involved in drug resistance to Gem in lung cancer, and this function may be mediated by epithelial–mesenchymal transition and the MRP1 pathway.

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.

An increase in integrin-linked kinase non-canonically confers NF-κB-mediated growth advantages to gastric cancer cells by activating ERK1/2

Background

Increased activity or expression of integrin-linked kinase (ILK), which regulates cell adhesion, migration, and proliferation, leads to oncogenesis. We identified the molecular basis for the regulation of ILK and its alternative role in conferring ERK1/2/NF-κB-mediated growth advantages to gastric cancer cells.

Results

Inhibiting ILK with short hairpin RNA or T315, a putative ILK inhibitor, abolished NF-κB-mediated the growth in the human gastric cancer cells AGS, SNU-1, MKN45, and GES-1. ILK stimulated Ras activity to activate the c-Raf/MEK1/2/ERK1/2/ribosomal S6 kinase/inhibitor of κBα/NF-κB signaling by facilitating the formation of the IQ motif-containing GTPase-activating protein 1 (IQGAP1)–Ras complex. Forced enzymatic ILK expression promoted cell growth by facilitating ERK1/2/NF-κB signaling. PI3K activation or decreased PTEN expression prolonged ERK1/2 activation by protecting ILK from proteasome-mediated degradation. C-terminus of heat shock cognate 70 interacting protein, an HSP90-associated E3 ubiquitin ligase, mediated ILK ubiquitination to control PI3K- and HSP90-regulated ILK stabilization and signaling. In addition to cell growth, the identified pathway promoted cell migration and reduced the sensitivity of gastric cancer cells to the anticancer agents 5-fluorouracil and cisplatin. Additionally, exogenous administration of EGF as well as overexpression of EGFR triggered ILK- and IQGAP1-regulated ERK1/2/NF-κB activation, cell growth, and migration.

Conclusion

An increase in ILK non-canonically promotes ERK1/2/NF-κB activation and leads to the growth of gastric cancer cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12964-014-0069-3) contains supplementary material, which is available to authorized users.

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.

Nuclear receptor-binding protein 1: a novel tumour suppressor and pseudokinase

Pseudokinases are a class of kinases which are structurally designated as lacking kinase activity. Despite the lack of kinase domain sequence conservation, there is increasing evidence that a number of pseudokinases retain kinase activity and/or have critical cellular functions, casting aside previous notions that pseudokinases simply exist as redundant kinases. Moreover, a number of recent studies have implicated pseudokinases as critical components in cancer formation and progression. The present review discusses the interactions and potential functions that nuclear receptor-binding protein 1, a pseudokinase recently described to have a tumour-suppressive role in cancer, may play in cellular homoeostasis and protein regulation. The recent findings highlighted in the present review emphasize the requirement to fully determine the function of pseudokinases in vitro and in vivo, the understanding of which may ultimately uncover new directions for drug discovery.

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.

Integrin-linked kinase functions as a tumor promoter in bladder transitional cell carcinoma

The aim of this study was to elucidate the role of the integrin-linked kinase (ILK) gene in development of human bladder transitional cell carcinoma (BTCC). Expression of ILK protein and ILK mRNA in 56 cases of human BTCC tissue and in 30 cases of adjacent normal bladder tissue was detected by immunohistochemistry S-P and reverse transcription polymerase chain reaction (RT-PCR), respectively. Four specific miRNA RNAi vectors targeting human ILK were synthesized and transfected into BIU-87 cells by liposome to obtain stable expression cell strains. The influence of ILK on proliferation of BTCC was detected by MTT, FCM on athymic mouse tumorigenesis. The positive rate of ILK protein in BTCC tissue (53.6%) was much higher than adjacent normal bladder tissue (10.0%) (p<0.05). Similarly, expression of ILK mRNA in BTCC tissue (0.540 ± 0.083) was significantly higher than in adjacent normal bladder tissue (0.492 ± 0.070) (p<0.05). MTT showed that the proliferation ability of miRNA-ILK transfected group was clearly decreased (p<0.05), the cell cycle being arrested in G0/G1-S, an tumorigenesis in vivo was also significantly reduced (p<0.05). ILK gene transcription and protein expression may be involved in the development of BTCC, so that ILK might be the new marker for early diagnosis and the new target for gene treatment.

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.

Down-regulated miR-625 suppresses invasion and metastasis of gastric cancer by targeting ILK

Accumulating evidence has shown that microRNAs are involved in multiple processes in cancer development and progression. Here, we report that expression of miR-625 is significantly down-regulated and negatively correlated with lymph node metastasis in gastric cancer. miR-625 significantly inhibits invasion and metastasis of gastric cancer cells both in vitro and in vivo. Moreover, we identify that ILK is a direct target gene for miR-625 and knockdown of ILK has a phenocopy of overexpression of miR-625. Taken together, our findings suggest that miR-625 plays an important role in the mechanism of tumor metastasis.

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.