3611

ILK

integrin-linked kinase;ILK;integrin-linked kinase

59 kDa serine/threonine-protein kinase|epididymis secretory protein Li 28|integrin-linked kinase-2|integrin-linked protein kinase

11p15.4

protein-coding

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-kappaB (NF-kappaB) inhibitor BAY 11-7028 or small interfering RNA targeting NF-kappaB p65, indicating an involvement of NF-kappaB 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.

The integrin-linked kinase (ILK)-PINCH1-alpha-parvin (IPP) complex functions as a signaling platform for integrins that modulates various cellular processes. ILK functions as a central adaptor for the assembly of IPP complex. We report here that mda-9/syntenin, a positive regulator of cancer metastasis, regulates the activation of Akt (also known as protein kinase B) by facilitating ILK adaptor function during adhesion to type I collagen (COL-I) in human breast cancer cells. COL-I stimulation induced the phosphorylation and plasma membrane translocation of Akt. Inhibition of mda-9/syntenin or expression of mutant ILK (E359K) significantly blocked the translocation of both ILK and Akt to the plasma membrane. mda-9/syntenin associated with ILK, and this association was increased at the plasma membrane by COL-I stimulation. Knockdown of mda-9/syntenin impaired COL-I-induced association of ILK with Akt and plasma membrane targeting of ILK-Akt complex. These results demonstrated that mda-9/syntenin regulates the activation of Akt by controlling the plasma membrane targeting of Akt via a mechanism that facilitates the association of Akt with ILK at the plasma membrane during adhesion to COL-I. On a striking note, inhibition of mda-9/syntenin impaired COL-I-induced plasma membrane translocation of the IPP complex and assembly of integrin beta1-IPP signaling complexes. Thus, our study defines the role of mda-9/syntenin in ILK adaptor function and describes a new mechanism of mda-9/syntenin for regulation of cell migration.

CTEN/TNS4 is an oncogene in colorectal cancer (CRC), which can induce cell motility although its mechanistic basis of activity and the clinical implications of Cten expression are unknown. As Cten is in complex with integrins at focal adhesions, we hypothesised that it may interact with integrin-linked kinase (ILK). Through forced expression and knockdown of Cten in HCT116 and SW620 (respectively, showing low and high Cten expression), we showed that Cten could regulate ILK. However, inhibition of ILK after forced expression of Cten abrogated the motility-inducing effects of Cten, thereby demonstrating that the Cten-ILK interaction was functionally relevant. Combined knockdown of Cten and ILK had no additive effects on cell motility compared with knockdown of each individually. In order to investigate the clinical implications of Cten expression, a series of 462 CRCs were evaluated by immunohistochemistry. High expression of Cten was associated with advanced Dukes' stage (P<0.001), poor prognosis (P<0.001) and distant metastasis (P=0.008). The role of Cten in metastasis was tested by (a) intrasplenic injection of CRC cells stably transfected with a Cten expression vector into nude mice and (b) testing a series of primary human CRCs and their metastases by immunohistochemistry. Compared with controls, mice injected with cells expressing Cten developed larger tumours in the spleen (P<0.05) and liver (P<0.05). In the human cases, compared with primary tumours, the metastatic deposits had a significantly higher frequency of nuclear localisation of Cten (P=0.002). We conclude that Cten expression is of prognostic significance in CRC, and we delineate a Cten-ILK pathway controlling cell motility and possibly promoting metastasis.

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)-kappaB inhibitor BAY 11-7028 or NF-kappaB 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-kappaB activation. Overall, our study demonstrates a pivotal role of ILK in EMT and metastasis, and suggests novel therapeutic opportunities for the treatment of CRC.

BACKGROUND AND AIM: Integrin-linked kinase has been implicated in metastasis of human tumors. Recent studies have also shown that the down-regulation of integrin-linked kinase has anti-tumor potential by inhibiting the metastatic potential of several types of cultured human cancer cells. However, the mechanism by which integrin-linked kinase regulates metastasis in human gastric carcinoma is not fully clear. We investigated the effect of integrin-linked kinase deletion on metastasis-associated markers in human gastric carcinoma SGC-7901 cell lines. METHODS: We generated cell lines depleted for integrin-linked kinase. Cell adhesion and invasion were measured by the MTS assay and transwell assay. The cell cycle was measured by flow cytometry. expression of metastasis-related genes was assessed by reporter assay, quantitative RT-PCR and western blotting. RESULTS: Our data showed an inhibitory effect on cell adhesion and invasion after silencing of integrin-linked kinase. The cell cycle was slowed in S/G2/M phases. metastasis-related genes E-cadherin, MMP-2/9 and cystatin B, as well as the signaling molecules p-Akt, NF-kappaB, and AP-1 activation, were also modulated. Our results indicate that integrin-linked kinase plays an important role in metastasis of human gastric carcinoma cells. CONCLUSIONS: Down-regulation of integrin-linked kinase resulted in the impairment of the metastatic potential of gastric tumor cells by regulating metastasis-related gene expression, by inhibiting the Akt pathway as well as the activity of transcription factors. Integrin-linked kinase could be used as a potential therapeutic target.

OBJECTIVE: To study whether Integrin linked kinase (ILK) is involved in the development and progression of laryngeal squamous cell carcinomas (LSCC). METHOD: We examined the expression of ILK in 64 LSCC (LSCC group) and 10 normal laryngeal mucosa (control group) using reverse transcription polymerase chain reaction (RT-PCR) and analyzed the relationship with clinic pathological parameters. RESULT: The expression of ILK mRNA was significantly higher in 64 LSCC tissue (0. 644 +/- 0. 098) than in normal laryngeal mucosa tissues (0.032 +/- 0.026, P <0.05). The expression of ILK mRNA in LSCC with the metastasis of lymph nodes (0. 867 +/- 0.247) was significantly higher than those without metastasis (0.389 +/- 0.199, P <0.05). With the development of clinical T-stages of LSCC, the expression of ILK mRNA in LSCC increases. There was no significant difference between different clinical stage groups (P > 0.05). CONCLUSION: These results suggest that ILK may participate not only in LSCC but also in invasion and metastasis of LSCC. ILK might be a novel molecular marker for prognosticating metastases and prognosis of LSCC.

Integrin-linked kinase (ILK) is an intracellular protein, which interacts with the cytoplasmic domains of integrin beta and beta3 subunits. ILK is a 59 kDa protein containing a phosphoinositide phospholipid-binding domain flanked by an N-terminal ankyrin repeat domain and a C-terminal serine/threonine protein kinase domain. Genetic and biochemical evidence have established an essential role of ILK in connecting integrins to the actin cytoskeleton. Apart from integrins, ILK interacts with several adaptor and signaling proteins resulting in its activation and localization to focal adhesion plaques. The kinase activity of ILK is stimulated upon integrin engagement, as well as by growth factors and chemokines in a PI-3Kinase-dependent manner. ILK can mediate the phosphorylation of a variety of intracellular substrates, most notable of which are: protein kinase B (PKB/Akt), glycogen synthase kinase-3 (GSK-3) and myosin light chain. Gain and loss of function strategies have shown that overexpression, and/or constitutive activation of ILK results in oncogenic transformation and progression to invasive and metastatic phenotypes. In addition ILK expression and activity are upregulated in several types of cancers. In this review, we summarize the adaptor and signaling properties ofILK, and also progress in the identification of therapeutic strategies for inhibition of ILK activity.

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.