Inhibition of ILK in PTEN-mutant human glioblastomas inhibits PKB/Akt activation, induces apoptosis, and delays tumor growth

CHI3L1 in the CSF is a potential biomarker for anti-leucine-rich glioma inactivated 1 encephalitis

Objective

Anti-leucine-rich glioma inactivated 1(LGI1) encephalitis is one rare autoimmune encephalitis which is accompanied by inflammatory responses. (Anti-leucine-rich glioma inactivated 1 (anti-LGI1) encephalitis is an autoimmune disease mediated by inflammatory responses.)This study aimed to investigate the Chitinase 3-like 1(CHI3L1) in anti-LGI1encephalitis patients and evaluate its association with modified Rankin Scale (mRS) score in anti-LGI1 encephalitis at admission and 6 months follow-up.(This study looked into the relationship between Chitinase 3-like 1 (CHI3L1) and the modified Ranking Scale (mRS) score in anti-LGI1 encephalitis patients at admission and 6 months later.).

Methods

Thirty-five patients with anti-LGI1 encephalitis and 22 patients with non-inflammatory neurological disease were enrolled in this study. (We enrolled 35 patients with anti-LGI1 encephalitis and 22 patients with non-inflammatory neurological disease.)Cerebrospinal fluid (CSF) and serum levels of CHI3L1 were measured by enzyme-linked immunosorbent assay. (We quantified CHI3L1 in the serum and cerebrospinal fluid (CSF) by performing an enzyme-linked immunosorbent assay.)Patients were evaluated for mRS score at admission and at 6 months follow-up.(We recorded the mRS score of the patients at admission and 6 months later.).

Results

CHI3L1 levels in CSF and serum were highly elevated in patients with anti-LGI1 encephalitis at admission compared those with the controls.(At admission, patients with anti-LGI1 encephalitis had elevated CHI3L1 levels in the CSF and serum.) Additionally, patients presenting with cognitive impairment had significantly higher CSF CHI3L1 levels and mRS scores than those without cognitive impairment symptoms. Patients presenting with only faciobrachial dystonic seizures at admission had lower CSF CHI3L1 levels than those with other symptoms. Finally, CSF CHI3L1 levels were positively correlated with CSF lactate levels.

Conclusion

CHI3L1 level in CSF is correlated with the severity and prognosis of anti-LGI1 encephalitis. (CSF CHI3L1 levels are correlated with the severity and prognosis of anti-LGI1 encephalitis.).

Anoikis resistance in diffuse glioma: The potential therapeutic targets in the future

Glioma is the most common malignant intracranial tumor and exhibits diffuse metastasis and a high recurrence rate. The invasive property of glioma results from cell detachment. Anoikis is a special form of apoptosis that is activated upon cell detachment. Resistance to anoikis has proven to be a protumor factor. Therefore, it is suggested that anoikis resistance commonly occurs in glioma and promotes diffuse invasion. Several factors, such as integrin, E-cadherin, EGFR, IGFR, Trk, TGF-β, the Hippo pathway, NF-κB, eEF-2 kinase, MOB2, hypoxia, acidosis, ROS, Hsp and protective autophagy, have been shown to induce anoikis resistance in glioma. In our present review, we aim to summarize the underlying mechanism of resistance and the therapeutic potential of these molecules.

Protective effect of Astragalus membranaceus and Astragaloside IV in sepsis-induced acute kidney injury

Background: Acute kidney injury (AKI) is the most common target organ damage in sepsis. Sepsis-associated AKI (SA-AKI) may be characterized by damage to the renal tubular epithelium. In this study, the pharmacological mechanisms of Astragalus membranaceus and its active monomer Astragaloside IV (AS-IV) were predicted based on a network pharmacology approach and validated both in vitro and in vivo using the SA-AKI model.

Method: We constructed an in vivo sepsis model using a mouse cecum ligation puncture (CLP) and HK-2 cells were treated with lipopolysaccharide (LPS) to mimic Gram (–) induced sepsis to assess the renal-protective efficacy of Astragalus membranaceus and AS-IV.

Results: The findings demonstrated that Astragalus membranaceus and AS-IV attenuate renal tubular injury in mice with polymicrobial sepsis, including vacuolization, loss of brush border, mitochondrial ultrastructural changes, and increased staining of kidney injury molecule-1 (KIM-1). AS-IV protected human proximal tubular epithelial (HK-2) cells against LPS induced cell viability loss. Both Astragalus membranaceus and AS-IV activated the PI3K/AKT pathway both in vitro and in vivo, as shown by Western blot and immunohistochemistry analysis.

Conclusion: The findings demonstrate that Astragalus membranaceus and AS-IV protect against sepsis-induced kidney tubular injury by activating the PI3K/AKT pathway.

Luteolin Attenuates Cognitive Dysfunction Induced By Chronic Cerebral Hypoperfusion Through the Modulation of The PI3K/Akt Pathway in Rats

Introduction

In our study, we evaluated the beneficial effect of luteolin in the treatment of cognitive dysfunction in rat models induced by cerebral hypoperfusion by two-vessel occlusion (2-VO).

Material and Methods

Seventy-five male Sprague Dawley rats were subjected to 2-VO surgery, in all but 15 (the sham group, group I) the ligation being permanent to impair cognitive abilities. The sham group rats received saline instead of a drug; 15 2-VO rats were not injected at all (the model group, group II); 15 2-VO rats were administered luteolin at 50 mg/kg b.w. (the lut 50 group, group III); to a further 15 luteolin was given at 100 mg/kg b.w. (the lut 100 group, group IV); and the final 15 received nimodipine at 16 mg/kg b.w. as positive controls (the nimodipine group, group V). Object recognition and Morris water maze tests were performed to investigate memory ability. A Western blot test was also conducted to assess expression of phosphatidylinositol 3-kinase (PI3K), its downstream target protein kinase B (Akt), and the phosphorylated form (P-Akt) in cerebral cortex and hippocampus tissue samples.

Results

Significant variations in the discrimination index in the object recognition test, the escape latencies in the Morris water maze test, and expression levels of PI3K-p110α and PI3K-p85 were observed three months after 2-VO surgery in both lut groups, with a significant change in the nimodipine group compared to the model group. P-Akt and Akt were expressed significantly higher in both lut groups and the nimodipine group than in the model group.

Conclusion

Luteolin treatment of rats cognitively dysfunctional after experimental cerebral hypo perfusion was neuroprotective by activating the PI3K/Akt signals which inhibit neuronal death in the cerebral cortex and hippocampal region.

The pseudogene PRELID1P6 promotes glioma progression via the hnHNPH1-Akt/mTOR axis

Research over the past decade has suggested important roles for pseudogenes in glioma. This study aimed to show that pseudogene PRELI domain-containing 1 pseudogene 6 (PRELID1P6) promotes glioma progression. Aberrant expression of genes was screened using The Cancer Genome Atlas database. We found that mRNA level of PRELID1P6 was highly upregulated in glioma and was associated with a shorter survival time. Functional studies showed that the knockdown of PRELID1P6 decreased cell proliferation, sphere formation, and clone formation ability and blocked the cell cycle transition at G0/G1, while overexpression of PRELID1P6 had the opposite effects. Mechanistically, knockdown of PRELID1P6 changed the cellular localization of heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) from nucleus to cytoplasm, which promoted ubiquitin-mediated degradation of hnRNPH1. RNA-sequence and gene set enrichment analysis suggested that knockdown of PRELID1P6 regulates the apoptosis signaling pathway. Western blotting showed that PRELID1P6 increased TRF2 expression by hnRNPH1-mediated alternative splicing effect and activated the Akt/mTOR pathway. Furthermore, Akt inhibitor MK2206 treatment reversed the oncogenic function of PRELID1P6. PRELID1P6 was also found to be negatively regulated by miR-1825. Our result showed that PRELID1P6 promotes glioma progression through the hnHNPH1-Akt/mTOR pathway. These findings shed new light on the important role of PRELID1P6 as a novel oncogene for glioma.

Chitinase-3 like-protein-1 function and its role in diseases

Non-enzymatic chitinase-3 like-protein-1 (CHI3L1) belongs to glycoside hydrolase family 18. It binds to chitin, heparin, and hyaluronic acid, and is regulated by extracellular matrix changes, cytokines, growth factors, drugs, and stress. CHI3L1 is synthesized and secreted by a multitude of cells including macrophages, neutrophils, synoviocytes, chondrocytes, fibroblast-like cells, smooth muscle cells, and tumor cells. It plays a major role in tissue injury, inflammation, tissue repair, and remodeling responses. CHI3L1 has been strongly associated with diseases including asthma, arthritis, sepsis, diabetes, liver fibrosis, and coronary artery disease. Moreover, following its initial identification in the culture supernatant of the MG63 osteosarcoma cell line, CHI3L1 has been shown to be overexpressed in a wealth of both human cancers and animal tumor models. To date, interleukin-13 receptor subunit alpha-2, transmembrane protein 219, galectin-3, chemo-attractant receptor-homologous 2, and CD44 have been identified as CHI3L1 receptors. CHI3L1 signaling plays a critical role in cancer cell growth, proliferation, invasion, metastasis, angiogenesis, activation of tumor-associated macrophages, and Th2 polarization of CD4⁺ T cells. Interestingly, CHI3L1-based targeted therapy has been increasingly applied to the treatment of tumors including glioma and colon cancer as well as rheumatoid arthritis. This review summarizes the potential roles and mechanisms of CHI3L1 in oncogenesis and disease pathogenesis, then posits investigational strategies for targeted therapies.

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.

Asiatic Acid Interferes with Invasion and Proliferation of Breast Cancer Cells by Inhibiting WAVE3 Activation through PI3K/AKT Signaling Pathway

Objective

To explore the ability of asiatic acid to interfere with the invasion and proliferation of breast cancer cells by inhibiting WAVE3 expression and activation through the PI3K/AKT signaling pathway.

Methods

The MDA-MB-231 cells with strong invasiveness were screened by transwell assay, and plasmids with high expression of WAVE3 were constructed for transfection. The transfection effect and protein expression level of plasmids were verified by PCR and WB. The effects of asiatic acid on cell proliferation and invasion were investigated by flow cytometry. The xenografted tumor models in nude mice were established to study the antitumor activity of asiatic acid.

Results

Asiatic acid significantly inhibited the activity of MDA-MB-231 cells, and the expression level of WAVE3 increased significantly in the tissue of ductal carcinoma in situ and was lower than that in the metastasis group. After plasmid transfection, the mRNA and protein expression of WAVE3 increased significantly in the cells. Asiatic acid at different concentrations had an impact on cell apoptosis and invasion and could significantly inhibit the expression of WAVE3, P53, p-PI3K, p-AKT, and other proteins. The T/C(%) of asiatic acid (50 mg/kg) for MDA-MB-231(F10) xenografted tumor in nude mice was 46.33%, with a tumor inhibition rate of 59.55%. Asiatic acid could significantly inhibit the growth of MDA-MB-231 (F10) xenografted tumors in nude mice (p < 0.05).

Conclusions

Asiatic acid interferes with the ability of breast cancer cells to invade and proliferate by inhibiting WAVE3 expression and activation and the mechanism of action may be related to the PI3K/AKT signaling pathway.

Integrin-Linked Kinase Deficiency in Collecting Duct Principal Cell Promotes Necroptosis of Principal Cell and Contributes to Kidney Inflammation and Fibrosis

BACKGROUND

Necroptosis is a newly discovered cell death pathway that plays a critical role in AKI. The involvement of integrin-linked kinase (ILK) in necroptosis has not been studied.

METHODS

We performed experiments in mice with an Ilk deletion in collecting duct (CD) principal cells (PCs), and cultured tubular epithelial cells treated with an ILK inhibitor or ILK siRNA knockdown.

RESULTS

Ilk deletion in CD PCs resulted in acute tubular injury and early mortality in mice. Progressive interstitial fibrosis and inflammation associated with the activation of the canonical TGF-β signaling cascade were detected in the kidneys of the mice lacking ILK in the CD PCs. In contrast to the minimal apoptosis detected in the animals' injured CDs, widespread necroptosis was present in ILK-deficient PCs, characterized by cell swelling, deformed mitochondria, and rupture of plasma membrane. In addition, ILK deficiency resulted in increased expression and activation of necroptotic proteins MLKL and RIPK3, and membrane translocation of MLKL in CD PCs. ILK inhibition and siRNA knockdown reduced cell survival in cultured tubular cells, concomitant with increased membrane accumulation of MLKL and/or phospho-MLKL. Administration of a necroptosis inhibitor, necrostatin-1, blocked cell death in vitro and significantly attenuated inflammation, interstitial fibrosis, and renal failure in ILK-deficient mice.

CONCLUSIONS

The study demonstrates the critical involvement of ILK in necroptosis through modulation of the RIPK3 and MLKL pathway and highlights the contribution of CD PC injury to the development of inflammation and interstitial fibrosis of the kidney.

Cornel iridoid glycoside improves cognitive impairment induced by chronic cerebral hypoperfusion via activating PI3K/Akt/GSK-3β/CREB pathway in rats

Chronic cerebral hypoperfusion is an important risk factor for vascular dementia (VaD) and other brain dysfunctions, for which there are currently no effective medications available. In the present study, we investigated the potential therapeutic effects of cornel iridoid glycoside (CIG) on VaD in rats modeled by permanent bilateral common carotid artery ligation (2-vessel occlusion, 2VO). The object recognition test (ORT) and Morris water maze (MWM) test were conducted to evaluate the learning and memory function. Western blot analysis and immunohistochemical staining were used to detect the expression of related proteins. Results showed that intragastric administration of CIG (30, 60, and 120 mg/kg) for 3 months significantly increased the discrimination index in ORT and decreased the escape latency in MWM test, ameliorating the learning and memory deficit in 2VO rats. Further data indicated that CIG increased the expression of neurotrophic factors (NGF and BDNF) and their receptors (TrkA and TrkB), glutamate receptor subunits (NMDAR1 and GluR2) in the cerebral cortex and hippocampus of 2VO rats. In addition, CIG elevated the expression of PI3K subunits p110α and p85, further upregulated the phosphorylation of Akt, GSK3β-ser9 and CREB in the cerebral cortex and hippocampus at 3 months after 2VO surgery. Collectively, CIG treatment improved learning and memory deficit induced by chronic cerebral hypoperfusion via increasing neurotrophic factors thus protecting glutamate receptors and activating PI3K/Akt/GSK3β/CREB signaling pathway in rats. These results suggest that CIG may be beneficial to VaD therapy.

Rsu1-dependent control of PTEN expression is regulated via ATF2 and cJun

The Rsu1 protein contributes to cell adhesion and migration via its association with the adaptor complex of Integrin linked kinase (ILK), PINCH, and Parvin (IPP), which binds to the cytoplasmic domain of β1 integrins joining integrins to the actin cytoskeleton. Rsu1 binding to PINCH in the IPP complex is required for EGF-induced adhesion, spreading and migration in MCF10A mammary epithelial cells. In addition, Rsu1 expression inhibits Jun kinase but is necessary for the activation of MKK4 and p38 Map kinase signaling essential for migration in MCF10A cells. The data reported here examines the links between MKK4-p38-ATF2 signaling and AKT regulation in MCF10A cells. Ectopic Rsu1 inhibited AKT1 phosphorylation while Rsu1 depletion induced AKT activation and AKT1 phosphorylation of MKK4 on serine 80, blocking MKK4 activity. Rsu1 depletion also reduced the RNA for lipid phosphatase PTEN thus implicating PTEN in modulating levels of activated AKT in these conditions. ChIP analysis of the PTEN promoter revealed that Rsu1 depletion prevented binding of ATF2 to a positive regulatory site in the PTEN promoter and the enhanced binding of cJun to a negatively regulatory PTEN promoter site. These results demonstrate a mechanism by which Rsu1 adhesion signaling alters the balance between MKK4-p38-ATF2 and cJun activation thus altering PTEN expression in MCF10A cells.

Insulin-like growth factor 1/insulin-like growth factor 1 receptor signaling protects against cell apoptosis through the PI3K/AKT pathway in glioblastoma cells

Glioblastoma multiforme (GBM) is a malignant tumor caused by complex pathological mechanisms, and is characterized by a high rate of cancer-related mortality and poor patient prognosis. Overgrowth of cancer cells, which results from the inhibition of cell apoptosis and/or the promotion of cell proliferation, leads to the progression of GBM. Therefore, studies into the regulatory mechanisms of cancer cell growth in GBM are required to identify potential therapeutic targets and improve treatment for GBM. In the present study, the role of insulin-like growth factor 1 (IGF1)/IGF1 receptor (IGF1R) signaling in the survival of GBM cells was evaluated. It was observed that IGF1 significantly inhibited the intrinsic and extrinsic pathways of apoptosis (P<0.05), and overexpression of IGF1R significantly promoted the survival of GBM cells (P<0.05). Moreover, both exogenous IGF1 and overexpression of IGF1R promoted the phosphorylation of protein kinase B (AKT), and inhibition of the phosphoinositide 3-kinase (PI3K)/AKT pathway significantly attenuated the inhibitory effects of IGF1/IGF1R on GBM apoptosis (P<0.05). Collectively, these findings indicate that IGF1/IGF1R promotes the survival of GBM cells through activation of the PI3K/AKT pathway. Therefore, inhibition of IGF1/IGF1R may be a viable therapeutic strategy to suppress the progression of GBM.

Veterinary drug, 17β-trenbolone promotes the proliferation of human prostate cancer cell line through the Akt/AR signaling pathway

Trenbolone acetate (TBA) is a synthetic anabolic steroidal growth factor that is used for rapid muscle development in cattle. The absorbed TBA is hydrolyzed to the active form, 17β-trenbolone (17 TB; 17β-hydroxy-estra-4,9,11-trien-3-one) in meat and milk products, which can cause adverse health effects in humans. Similar to 5α-dihydrotestosterone (DHT), 17 TB was reported to exhibit endocrine disrupting effects on animals and humans due to its androgenic effect via binding to the androgen receptor. The purpose of this study is to investigate the molecular mechanism of cell proliferation in prostate cancer (PCa) cells treated with 17 TB. We found that 17 TB induces AR-dependent cell proliferation in the human prostate cancer cell line, 22Rv1 in a concentration dependent manner. Treatment with 17 TB increased the expression of cell cycle regulatory proteins, cyclin D2/CDK-4 and cyclin E/CDK-2, whereas the expression of p27 was down-regulated. Furthermore, phosphorylation of Rb and activation of E2F were also induced, which suggests the activation of cyclin D2/CDK-4 and cyclin E/CDK-2 in the cells. When 22Rv1 cells were exposed to 30 pM of 17 TB, which is the effective concentration (EC₅₀) value required to observe proliferative effects on 22Rv1 cells, the expression levels of the phosphorylated forms of Akt and GSK3β were increased. This study demonstrates that 17 TB induces AR-dependent proliferation through the modulation of cell cycle-related proteins in the Akt signaling pathway. The present study provides an effective methodology for identifying cell proliferation signaling of veterinary drugs that exert AR agonistic effects.

Peripheral insulin resistance in ILK-depleted mice by reduction of GLUT4 expression

The development of insulin resistance is characterized by the impairment of glucose uptake mediated by glucose transporter 4 (GLUT4). Extracellular matrix changes are induced when the metabolic dysregulation is sustained. The present work was devoted to analyze the possible link between the extracellular-to-intracellular mediator integrin-linked kinase (ILK) and the peripheral tissue modification that leads to glucose homeostasis impairment. Mice with general depletion of ILK in adulthood (cKD-ILK) maintained in a chow diet exhibited increased glycemia and insulinemia concurrently with a reduction of the expression and membrane presence of GLUT4 in the insulin-sensitive peripheral tissues compared with their wild-type littermates (WT). Tolerance tests and insulin sensitivity indexes confirmed the insulin resistance in cKD-ILK, suggesting a similar stage to prediabetes in humans. Under randomly fed conditions, no differences between cKD-ILK and WT were observed in the expression of insulin receptor (IR-B) and its substrate IRS-1 expressions. The IR-B isoform phosphorylated at tyrosines 1150/1151 was increased, but the AKT phosphorylation in serine 473 was reduced in cKD-ILK tissues. Similarly, ILK-blocked myotubes reduced their GLUT4 promoter activity and GLUT4 expression levels. On the other hand, the glucose uptake capacity in response to exogenous insulin was impaired when ILK was blocked in vivo and in vitro, although IR/IRS/AKT phosphorylation states were increased but not different between groups. We conclude that ILK depletion modifies the transcription of GLUT4, which results in reduced peripheral insulin sensitivity and glucose uptake, suggesting ILK as a molecular target and a prognostic biomarker of insulin resistance.

ILK and cytoskeletal architecture: an important determinant of AQP2 recycling and subsequent entry into the exocytotic pathway

Within the past decade tremendous efforts have been made to understand the mechanism behind aquaporin-2 (AQP2) water channel trafficking and recycling, to open a path toward effective diabetes insipidus therapeutics. A recent study has shown that integrin-linked kinase (ILK) conditional-knockdown mice developed polyuria along with decreased AQP2 expression. To understand whether ILK also regulates AQP2 trafficking in kidney tubular cells, we performed in vitro analysis using LLCPK1 cells stably expressing rat AQP2 (LLC-AQP2 cells). Upon treatment of LLC-AQP2 cells with ILK inhibitor cpd22 and ILK-siRNA, we observed increased accumulation of AQP2 in the perinuclear region, without any significant increase in the rate of endocytosis. This perinuclear accumulation did not occur in cells expressing a serine-256-aspartic acid mutation that retains AQP2 in the plasma membrane. We then examined clathrin-mediated endocytosis after ILK inhibition using rhodamine-conjugated transferrin. Despite no differences in overall transferrin endocytosis, the endocytosed transferrin also accumulated in the perinuclear region where it colocalized with AQP2. These accumulated vesicles also contained the recycling endosome marker Rab11. In parallel, the usual vasopressin-induced AQP2 membrane accumulation was prevented after ILK inhibition; however, ILK inhibition did not measurably affect AQP2 phosphorylation at serine-256 or its dephosphorylation at serine-261. Instead, we found that inhibition of ILK increased F-actin polymerization. When F-actin was depolymerized with latrunculin, the perinuclear located AQP2 dispersed. We conclude that ILK is important in orchestrating dynamic cytoskeletal architecture during recycling of AQP2, which is necessary for its subsequent entry into the exocytotic pathway.

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.

Effects of phoxim on nutrient metabolism and insulin signaling pathway in silkworm midgut

Silkworm (Bombyx mori) is an important economic insect. Each year, poisoning caused by phoxim pesticide leads to huge economic losses in sericulture in China. Silkworm midgut is the major organ for food digestion and nutrient absorption. In this study, we found that the activity and expression of nutrition metabolism-related enzymes were dysregulated in midgut by phoxim exposure. DGE analysis revealed that 40 nutrition metabolism-related genes were differentially expressed. qRT-PCR results indicated that the expression levels of insulin/insulin growth factor signaling (IIS) pathway genes Akt, PI3K, PI3K60, PI3K110, IRS and PDK were reduced, whereas PTEN's expression was significantly increased in the midgut at 24 h after phoxim treatment. However, the transcription levels of Akt, PI3K60, PI3K110, IRS, InR and PDK were elevated and reached the peaks at 48 h, which were 1.48-, 1.35-, 1.21-, 2.24-, 2.89-, and 1.44-fold of those of the control, respectively. At 72 h, the transcription of these genes was reduced. Akt phosphorylation level was increasing along with the growth of silkworms in the control group. However, phoxim treatment led to increased Akt phosphorylation that surged at 24 h but gradually decreased at 48 h and 72 h. The results indicated that phoxim dysregulated the expression of IIS pathway genes and induced abnormal nutrient metabolism in silkworm midgut, which may be the reason of the slow growth of silkworms.

Nanoparticle-Loaded Protein-Polymer Nanodroplets for Improved Stability and Conversion Efficiency in Ultrasound Imaging and Drug Delivery

A new formulation of volatile nanodroplets stabilized by a protein and polymer coating and loaded with magnetic nanoparticles is developed. The droplets show enhanced stability and phase conversion efficiency upon ultrasound exposure compared with existing formulations. Magnetic targeting, encapsulation, and release of an anticancer drug are demonstrated in vitro with a 40% improvement in cytotoxicity compared with free drug.

Androgen receptor promotes gastric cancer cell migration and invasion via AKT-phosphorylation dependent upregulation of matrix metalloproteinase 9

Androgen receptor (AR) plays an important role in many kinds of cancers. However, the molecular mechanisms of AR in gastric cancer (GC) are poorly characterized. Here, we investigated the role of AR in GC cell migration, invasion and metastatic potential. Our data showed that AR expression was positively correlated with lymph node metastasis and late TNM stages. These findings were accompanied by activation of AKT and upregulation of matrix metalloproteinase 9 (MMP9). AR overexpression induced increases in GC cell migration, invasion and proliferation in vitro and in vivo. These effects were attenuated by inhibition of AKT, AR and MMP9. AR overexpression upregulated MMP9 protein levels, whereas this effect was counteracted by AR siRNA. Inhibition of AKT by siRNA or an inhibitor (MK-2206 2HC) decreased AR protein expression in both stably transfected and parental SGC-7901 cells. Luciferase reporter and chromatin immunoprecipitation assays demonstrated that AR bound to the AR-binding sites of the MMP9 promoter. In summary, AR overexpression induced by AKT phosphorylation upregulated MMP9 by binding to its promoter region to promote gastric carcinogenesis. The AKT/AR/MMP9 pathway plays an important role in GC metastasis and may be a novel therapeutic target for GC treatment.

Releasing 'brakes' to nerve regeneration: intrinsic molecular targets

Restoring critical neuronal architecture after peripheral nerve injury is challenging. Although immediate regenerative responses to peripheral axon injury involve the synthesis of regeneration-associated proteins in neurons and Schwann cells, an unfavorable balance between growth facilitatory and growth inhibitory signaling impairs the growth continuum of injured peripheral nerves. Molecules involved with the signaling network of tumor suppressors play crucial roles in shifting the balance between growth and restraint during axon regeneration. An understanding of the molecular framework of tumor suppressor molecules in injured neurons and its impact on stage-specific regeneration events may expose therapeutic intervention points. In this review we discuss how signaling networks of the specific tumor suppressors PTEN, Rb1, p53, p27 and p21 are altered in injured peripheral nerves and how this impacts peripheral nerve regeneration. Insights into the roles and importance of these pathways may open new avenues for improving the neurological deficits associated with nerve injury.

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.

Effect of uraemia on endothelial cell damage is mediated by the integrin linked kinase pathway

KEY POINTS

Patients with chronic kidney disease have a higher risk of developing cardiovascular diseases than the general population. Their vascular endothelium is dysfunctional, among other things, because it is permanently exposed to uraemic toxins, several of which have poor clearance by conventional dialysis. Recent studies have demonstrated the important role of integrin-linked kinase (ILK) in the maintenance of endothelial integrity and in this study we investigate the involvement of ILK in the mechanism underlying vascular endothelial damage that occurs in uraemia. For the first time, we demonstrate the implication of ILK in the protection against endothelial cell damage (inhibition of proliferation, toxicity, oxidative stress and programed cell death) induced by uraemic serum from chronic kidney disease patients and uraemic toxins. This molecular mechanism may have clinical relevance because it highlights the importance of maintaining high levels of ILK activity to help preserve endothelial integrity, at least in early stages of chronic kidney disease.

ABSTRACT

Patients with chronic kidney disease (CKD) have a higher risk of developing cardiovascular diseases. Their vascular endothelium is dysfunctional, among other things, because it is permanently exposed to uraemic toxins, several of which, mostly protein-bound compounds such as indoxyl sulfate (IS) and p-cresyl sulphate, having poor clearance by conventional dialysis, induce endothelial toxicity. However, the molecular mechanism by which uraemic toxins regulate early stages of endothelial dysfunction remains unclear. Recent studies have demonstrated the important role of integrin-linked kinase (ILK) in the maintenance of endothelial integrity. In this study, we investigate the involvement of ILK in the mechanism underlying vascular endothelial damage that occurs in uraemia. First, we show that incubation of EA.hy926 cells with human uraemic serum from CKD patients upregulates ILK activity. This ILK activation also occurs when the cells are exposed to IS (25-100 μg ml(-1)), p-cresol (10-100 μg ml(-1)) or both combined, compared to human serum control. Next, we observed that high doses of both toxins together induce a slight decrease in cell proliferation and increase apoptosis and reactive oxygen species production. Interestingly, these toxic effects displayed a strong increase when the ILK protein is knocked down by small interfering RNA, even at low doses of uraemic toxins. Abrogation of AKT has demonstrated the ILK/AKT signalling pathway involved in these processes. This study has demonstrated the implication of ILK in the protection against endothelial cell damage induced by uraemic toxins, a molecular mechanism that could play a protective role in the early stages of endothelial dysfunction observed in uraemic patients.

In vitro antitumor activity of stellettin B, a triterpene from marine sponge Jaspis stellifera, on human glioblastoma cancer SF295 cells

Stellettin B was isolated from marine sponge Jaspis stellifera. In vitro antitumor activities were investigated on 39 human cancer cell lines. Stellettin B exhibited highly potent inhibition against the growth of a human glioblastoma cell line SF295, with a GI50 of 0.01 μM. In contrast, stellettin B showed very weak inhibitory activity on normal cell lines including HMEC, RPTEC, NHBE and PrEC, with GI50s higher than 10 μM, suggesting its relatively selective cytotoxicity against human cancer cells compared to normal human cell lines. We then focused on the antitumor activity of this compound on SF295 cells. Flow cytometric analysis indicated that stellettin B induced apoptosis in SF295 cells in a concentration-dependent manner. Further study indicated that stellettin B increased the production of ROS, the activity of caspase 3/7, as well as the cleavage of PARP, each of which is known to be involved in apoptosis. To investigate the molecular mechanism for cell proliferation inhibition and apoptosis induction, effect on the phosphorylation of several signal proteins of PI3K/Akt and RAS/MAPK pathways was examined. Stellettin B inhibited the phosphorylation of Akt potently, with no activity on p-ERK and p-p38, suggesting that inhibition of PI3K/Akt pathway might be involved in the antiproliferative and apoptosis-inducing effect. However, homogenous time-resolved fluorescence (HTRF) assay indicated that stellettin B did not inhibit PI3K activity, suggesting that the direct target might be signal protein upstream of Akt pathway other than PI3K.

USP15 stabilizes MDM2 to mediate cancer-cell survival and inhibit antitumor T cell responses

Deubiquitinases (DUBs) are a new class of drug targets, although the physiological function of only few DUBs has been characterized. Here we identified the DUB USP15 as a crucial negative regulator of T cell activation. USP15 stabilized the E3 ubiquitin ligase MDM2, which in turn negatively regulated T cell activation by targeting the degradation of the transcription factor NFATc2. USP15 deficiency promoted T cell activation in vitro and enhanced T cell responses to bacterial infection and tumor challenge in vivo. USP15 also stabilized MDM2 in cancer cells and regulated p53 function and cancer-cell survival. Our results suggest that inhibition of USP15 may both induce tumor cell apoptosis and boost antitumor T cell responses.

Role of Akt in human malignant glioma: from oncogenesis to tumor aggressiveness

Gathering evidence has revealed that Akt signaling pathway plays an important role in glioma progression and aggressiveness. Among Akt kinases the most studied, Akt1, has been involved in many cellular processes that are in favor of cell malignancy. More recently, the actions of the two other isoforms, Akt2 and Akt3 have emerged in glioma. After a description of Akt pathway activation, we will explore the role of each isoform in malignant glioma that strengthens the current preclinical and clinical studies evaluating the impact of Akt pathway targeting in glioblastomas.

Malignant gliomas: strategies to increase the effectiveness of targeted molecular treatment

Recently, there has been increasing interest in the use of targeted molecular agents for the treatment of malignant gliomas. These agents are generally well tolerated but have demonstrated only modest activity. In this article, the current status of targeted molecular agents for malignant gliomas will be reviewed and strategies to improve their effectiveness will be discussed.

HDAC inhibitor DWP0016 activates p53 transcription and acetylation to inhibit cell growth in U251 glioblastoma cells

Here we report a hydroacid named DWP0016, which exhibited HDAC inhibition and induced p53 acetylation in U251 glioblastoma cells. DWP0016 effectively inhibited the cell growth of U251 cells and other four carcinoma cell lines but did not affect the normal cells. Cell cycle distribution analysis showed DWP0016 arrested at G1 phase cell cycle dose-dependently in U251 cells. DWP0016 induced caspase-dependent and independent apoptosis in U251 cells, which was identified by flow cytometry analysis, caspases activity analysis, Western blotting assay, and caspases inhibition. Mechanisms research suggested that DWP0016 activated transcription and acetylation of tumor suppressor p53. DWP0016 regulated p300, CBP, and PCAF to facilitate p53 acetylation at lys382 in U251 cells. In addition, activation of p53 by DWP0016 promoted PUMA to catalyze mitochondrial pathway. Besides, siRNA assay indicated p53 was the key gene to induce growth inhibition, cell cycle arrest, and apoptosis in DWP0016 treated U251 cells. Conclusively, our results show DWP0016 is a potent HDAC inhibitor and the anti-tumor activity is consistent with its intended p53 activation mechanisms. These findings indicate the promising antitumor potential of DWP0016 for further glioblastoma treatment applications.

Type II cGMP-dependent protein kinase inhibits epidermal growth factor-induced phosphatidylinositol-3-kinase/Akt signal transduction in gastric cancer cells

Our previous study revealed that Type II cGMP-dependent protein kinase (PKG II) inhibits epidermal growth factor (EGF)-induced MAPK/ERK and MAPK/JNK-mediated signal transduction through the inhibition of the phosphorylation/activation of the EGF receptor (EGFR). As EGFR also mediates several other signal transduction pathways besides MAPK-mediated pathways, the present study was designed to investigate whether PKG II was able to inhibit EGF/EGFR-induced phosphatidylinositol-3-kinase (PI3K)/Akt-mediated signal transduction. The AGS human gastric cancer cell line was infected with adenoviral constructs encoding a cDNA of PKG II (Ad-PKG II) to increase the expression of PKG II, and treated with 8-pCPT-cGMP to activate the enzyme. Western blotting was used to detect the phosphorylation/activation of the key components of the signal transduction pathway, including EGFR, PI3K, Akt, mTOR and NF-κB. The levels of apoptosis-related proteins, including Bax, Bcl-2, caspase 9 and DNA fragment factor (DFF), were also determined by western blotting. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining was used to detect the apoptosis of the AGS cells. The results revealed that EGF treatment increased the phosphorylation (activation) of EGFR, PI3K, Akt and mTOR, and increased the nuclear localization (activation) of NF-κB. EGF treatment also reduced the apoptosis of the AGS cells and increased the expression of the anti-apoptotic protein, Bcl-2, but had no effect on the expression of the pro-apoptotic protein, Bax, and did not alter the levels of caspase 9 and DFF. Increasing the PKG II activity of AGS cells by infecting them with Ad-PKG II and stimulating them with 8-pCPT-cGMP inhibited the EGF-induced activation of EGFR, PI3K, Akt, mTOR and NF-κB; caused an increase in caspase 9 breakdown (activation) and DFF levels; and reversed the anti-apoptotic effect of EGF. The results suggest that PKG II may also inhibit EGF-induced signal transduction of PI3K/Akt-mediated pathways, and further confirm that PKG II is able to block the activation of EGFR.

Anoikis molecular pathways and its role in cancer progression

Anoikis is a programmed cell death induced upon cell detachment from extracellular matrix, behaving as a critical mechanism in preventing adherent-independent cell growth and attachment to an inappropriate matrix, thus avoiding colonizing of distant organs. As anchorage-independent growth and epithelial-mesenchymal transition, two features associated with anoikis resistance, are vital steps during cancer progression and metastatic colonization, the ability of cancer cells to resist anoikis has now attracted main attention from the scientific community. Cancer cells develop anoikis resistance due to several mechanisms, including change in integrins' repertoire allowing them to grow in different niches, activation of a plethora of inside-out pro-survival signals as over-activation of receptors due to sustained autocrine loops, oncogene activation, growth factor receptor overexpression, or mutation/upregulation of key enzymes involved in integrin or growth factor receptor signaling. In addition, tumor microenvironment has also been acknowledged to contribute to anoikis resistance of bystander cancer cells, by modulating matrix stiffness, enhancing oxidative stress, producing pro-survival soluble factors, triggering epithelial-mesenchymal transition and self-renewal ability, as well as leading to metabolic deregulations of cancer cells. All these events help cancer cells to inhibit the apoptosis machinery and sustain pro-survival signals after detachment, counteracting anoikis and constituting promising targets for anti-metastatic pharmacological therapy. This article is part of a Special Section entitled: Cell Death Pathways.

Functional Role of mTORC2 versus Integrin-Linked Kinase in Mediating Ser473-Akt Phosphorylation in PTEN-Negative Prostate and Breast Cancer Cell Lines

Although the rictor-mTOR complex (mTORC2) has been shown to act as phosphoinositide-dependent kinase (PDK)2 in many cell types, other kinases have also been implicated in mediating Ser473-Akt phosphorylation. Here, we demonstrated the cell line specificity of integrin-linked kinase (ILK) versus mTORC2 as PDK2 in LNCaP and PC-3 prostate and MDA-MB-468 breast cancer cells, of which the PTEN-negative status allowed the study of Ser473-Akt phosphorylation independent of external stimulation. PC-3 and MDA-MB-468 cells showed upregulated ILK expression relative to LNCaP cells, which expressed a high abundance of mTOR. Exposure to Ku-0063794, a second-generation mTOR inhibitor, decreased Ser473-Akt phosphorylation in LNCaP cells, but not in PC-3 or MDA-MB-468 cells. In contrast, treatment with T315, a novel ILK inhibitor, reduced the phosphorylation of Ser473-Akt in PC-3 and MDA-MB-468 cells without affecting that in LNCaP cells. This cell line specificity was verified by comparing Ser473-Akt phosphorylation status after genetic knockdown of rictor, ILK, and other putative Ser-473-Akt kinases. Genetic knockdown of rictor, but not ILK or the other kinases examined, inhibited Ser473-Akt phosphorylation in LNCaP cells. Conversely, PC-3 and MDA-MB-468 cells were susceptible to the effect of ILK silencing on Ser473-Akt phosphorylation, while knockdown of rictor or any of the other target kinases had no appreciable effect. Co-immunoprecipitation analysis demonstrated the physical interaction between ILK and Akt in PC-3 cells, and T315 blocked ILK-mediated Ser473 phosphorylation of bacterially expressed Akt. ILK also formed complexes with rictor in PC-3 and MDA-MB-468 cells that were disrupted by T315, but such complexes were not observed in LNCaP cells. In the PTEN-functional MDA-MB-231 cell line, both T315 and Ku-0063794 suppressed EGF-induced Ser473-Akt phosphorylation. Inhibition of ILK by T315 or siRNA-mediated knockdown suppressed epithelial-mesenchymal transition in MDA-MB-468 and PC-3 cells. Thus, we hypothesize that ILK might bestow growth advantage and metastatic potential in the course of tumor progression.

A novel role of ribonuclease inhibitor in regulation of epithelial-to-mesenchymal transition and ILK signaling pathway in bladder cancer cells

Human ribonuclease inhibitor (RI) is a cytoplasmic acidic protein possibly involved in biological functions other than the inhibition of RNase A and angiogenin activities. We have previously shown that RI can inhibit growth and metastasis in some cancer cells. Epithelial-mesenchymal transition (EMT) is regarded as the beginning of invasion and metastasis and has been implicated in the metastasis of bladder cancer. We therefore postulate that RI regulates EMT of bladder cancer cells. We find that the over-expression of RI induces the up-regulation of E-cadherin, accompanied with the decreased expression of proteins associated with EMT, such as N-cadherin, Snail, Slug, vimentin and Twist and of matrix metalloprotein-2 (MMP-2), MMP-9 and Cyclin-D1, both in vitro and in vivo. The up-regulation of RI inhibits cell proliferation, migration and invasion, alters cell morphology and adhesion and leads to the rearrangement of the cytoskeleton in vitro. We also demonstrate that the up-regulation of RI can decrease the expression of integrin-linked kinase (ILK), a central component of signaling cascades controlling an array of biological processes. The over-expression of RI reduces the phosphorylation of the ILK downstream signaling targets p-Akt and p-GSK3β in T24 cells. We further find that bladder cancer with a high-metastasis capability shows higher vimentin, Snail, Slug and Twist and lower E-cadherin and RI expression in human clinical specimens. Finally, we provide evidence that the up-regulation of RI inhibits tumorigenesis and metastasis of bladder cancer in vivo. Thus, RI might play a novel role in the development of bladder cancer through regulating EMT and the ILK signaling pathway.

Combined RNAi-mediated suppression of Rictor and EGFR resulted in complete tumor regression in an orthotopic glioblastoma tumor model

The PI3K/AKT/mTOR pathway is commonly over activated in glioblastoma (GBM), and Rictor was shown to be an important regulator downstream of this pathway. EGFR overexpression is also frequently found in GBM tumors, and both EGFR and Rictor are associated with increased proliferation, invasion, metastasis and poor prognosis. This research evaluated in vitro and in vivo whether the combined silencing of EGFR and Rictor would result in therapeutic benefits. The therapeutic potential of targeting these proteins in combination with conventional agents with proven activity in GBM patients was also assessed. In vitro validation studies were carried out using siRNA-based gene silencing methods in a panel of three commercially available human GBM cell lines, including two PTEN mutant lines (U251MG and U118MG) and one PTEN-wild type line (LN229). The impact of EGFR and/or Rictor silencing on cell migration and sensitivity to chemotherapeutic drugs in vitro was determined. In vivo validation of these studies was focused on EGFR and/or Rictor silencing achieved using doxycycline-inducible shRNA-expressing U251MG cells implanted orthotopically in Rag2M mice brains. Target silencing, tumor size and tumor cell proliferation were assessed by quantification of immunohistofluorescence-stained markers. siRNA-mediated silencing of EGFR and Rictor reduced U251MG cell migration and increased sensitivity of the cells to irinotecan, temozolomide and vincristine. In LN229, co-silencing of EGFR and Rictor resulted in reduced cell migration, and increased sensitivity to vincristine and temozolomide. In U118MG, silencing of Rictor alone was sufficient to increase this line’s sensitivity to vincristine and temozolomide. In vivo, while the silencing of EGFR or Rictor alone had no significant effect on U251MG tumor growth, silencing of EGFR and Rictor together resulted in a complete eradication of tumors. These data suggest that the combined silencing of EGFR and Rictor should be an effective means of treating GBM.

Deltonin induces apoptosis in MDA‑MB‑231 human breast cancer cells via reactive oxygen species‑mediated mitochondrial dysfunction and ERK/AKT signaling pathways

Deltonin, a steroidal saponin isolated from Dioscorea zingiberensis Wright, exhibits high cytotoxic activity in cancer cells. In the present study, the effects of deltonin on cell proliferation and apoptosis were evaluated in the MDA‑MB‑231 human breast carcinoma cell line. Following treatment with deltonin, the viability of MDA‑MB‑231 cells was analyzed using MTT assay and apoptosis, mitochondrial membrane potential (∆Ψm) alternation and intracellular reactive oxygen species (ROS) generation was determined by flow cytometry. In addition, western blot analysis was performed to examine the expression of apoptosis‑associated proteins. The results demonstrated that deltonin induced apoptosis in MDA‑MB‑231 cells in a time‑ and concentration‑dependent manner. Apoptosis was associated with depolarization of ∆Ψm and time‑dependent ROS generation. Deltonin treatment also resulted in Bax upregulation, Bcl-2 downregulation, activation of caspase‑3 and ‑8 and poly (ADP ribose) polymerase cleavage. Decreased levels of phosphorylated extracellular signal‑regulated kinase (ERK) and phosphorylated AKT were also observed. Results indicate that the proliferation inhibitory effect of deltonin is associated with its apoptosis‑inducing effect, which may correlate with ROS‑mediated mitochondrial dysfunction as well as activation of the ERK/AKT signaling pathways. Therefore, deltonin may be a potential chemotherapeutic agent for the treatment of breast cancer.

Integrin-linked kinase as a target for ERG-mediated invasive properties in prostate cancer models

Approximately half of prostate cancers (PCa) carry TMPRSS2-ERG translocations; however, the clinical impact of this genomic alteration remains enigmatic. Expression of v-ets erythroblastosis virus E26 oncogene like (avian) gene (ERG) promotes prostatic epithelial dysplasia in transgenic mice and acquisition of epithelial-to-mesenchymal transition (EMT) characteristics in human prostatic epithelial cells (PrECs). To explore whether ERG-induced EMT in PrECs was associated with therapeutically targetable transformation characteristics, we established stable populations of BPH-1, PNT1B and RWPE-1 immortalized human PrEC lines that constitutively express flag-tagged ERG3 (fERG). All fERG-expressing populations exhibited characteristics of in vitro and in vivo transformation. Microarray analysis revealed >2000 commonly dysregulated genes in the fERG-PrEC lines. Functional analysis revealed evidence that fERG cells underwent EMT and acquired invasive characteristics. The fERG-induced EMT transcript signature was exemplified by suppressed expression of E-cadherin and keratins 5, 8, 14 and 18; elevated expression of N-cadherin, N-cadherin 2 and vimentin, and of the EMT transcriptional regulators Snail, Zeb1 and Zeb2, and lymphoid enhancer-binding factor-1 (LEF-1). In BPH-1 and RWPE-1-fERG cells, fERG expression is correlated with increased expression of integrin-linked kinase (ILK) and its downstream effectors Snail and LEF-1. Interfering RNA suppression of ERG decreased expression of ILK, Snail and LEF-1, whereas small interfering RNA suppression of ILK did not alter fERG expression. Interfering RNA suppression of ERG or ILK impaired fERG-PrEC Matrigel invasion. Treating fERG-BPH-1 cells with the small molecule ILK inhibitor, QLT-0267, resulted in dose-dependent suppression of Snail and LEF-1 expression, Matrigel invasion and reversion of anchorage-independent growth. These results suggest that ILK is a therapeutically targetable mediator of ERG-induced EMT and transformation in PCa.

Integrin-linked kinase (ILK) expression correlates with tumor severity in clear cell renal carcinoma

Integrin-linked kinase (ILK) is an unique intracellular serine/threonine kinase and adapter protein. When dysregulated, it has been associated with increased cell proliferation, anchorage-independent cell growth, evasion of apoptosis, angiogenesis, invasion of surrounding tissues, downregulation of E-cadherin expression, nuclear translocation of β-catenin and metastasis, all features of tumoral malignancy. The objective of the present work was to evaluate the expression of ILK in clear cell renal carcinomas (CCRC) as a possible prognostic indicator. ILK immunoexpression was evaluated in a tissue microarray (TMA) with 45 human CCRCs. In addition, the apoptotic and proliferative indices and the immuno-expression of β-catenin and E-cadherin were also evaluated. E-cadherin expression was significantly decreased in tumors with positive ILK expression in relation to those with negative immunoexpression (p = 0.011). ILK immunostaining was significantly increased in high-grade in comparison to low-grade CCRCs (p = 0.0008). ILK expression was also associated with increased proliferative index (p = 0.020), tumor size >7.0 cm (p = 0.018) and with renal vein and capsule invasion (p = 0.003 and p = 0.00). Finally, tumors stage I and II (noninvasive) presented significantly reduced ILK immunoexpression when compared to stage III (locally invasive) (p = 0.0028). ILK immunoexpression in CCRC increases with loss of intercellular adhesion, nuclear grading, increased proliferative index and Robson stage. Altogether, our data suggest a possible role for ILK in the progression of CRCC.

Loss of PTEN is not associated with poor survival in newly diagnosed glioblastoma patients of the temozolomide era

INTRODUCTION

Pre-temozolomide studies demonstrated that loss of the tumor suppressor gene PTEN held independent prognostic significance in GBM patients. We investigated whether loss of PTEN predicted shorter survival in the temozolomide era. The role of PTEN in the PI3K/Akt pathway is also reviewed.

METHODS

Patients with histologically proven newly diagnosed GBM were identified from a retrospective database between 2007 and 2010. Cox proportional hazards analysis was used to calculate the independent effects of PTEN expression, age, extent of resection, Karnofsky performance scale (KPS), and treatment on overall survival.

RESULTS

Sixty-five percent of patients were men with median age of 63 years, and 70% had KPS≥80. Most patients (81%) received standard treatment (temozolomide with concurrent radiation). A total of 72 (47%) patients had retained PTEN expression. Median overall survival (OS) was 19.1 months (95% CI: 15.0-22.5). Median survival of 20.0 months (95% CI: 15.0-25.5) and 18.2 months (95% CI: 13.0-25.7) was observed in PTEN retained and PTEN loss patients, respectively (p = .71). PTEN loss patients were also found to have amplifications of EGFR gene more frequently than patients with retained PTEN (70.8% vs. 47.8%, p = .01). Multivariate analysis showed that older age (HR 1.64, CI: 1.02-2.63, p = .04), low KPS (HR 3.57, CI: 2.20-5.79, p<.0001), and lack of standard treatment (HR 3.98, CI: 2.38-6.65, p<.0001) yielded worse survival. PTEN loss was not prognostic of overall survival (HR 1.31, CI: 0.85-2.03, p = .22).

CONCLUSIONS

Loss of expression of PTEN does not confer poor overall survival in the temozolomide era. These findings imply a complex and non-linear molecular relationship between PTEN, its regulators and effectors in the tumorigenesis of glioblastoma. Additionally, there is evidence that temozolomide may be more effective in eradicating GBM cancer cells with PTEN loss and hence, level the outcomes between the PTEN retained and loss groups.

Novel anti-cancer compounds for developing combinatorial therapies to target anoikis-resistant tumors

Anoikis, a cell death pathway induced by loss of normal cell-matrix attachment or upon adhesion to a non-native matrix, ensures the balance between proliferative potential of normal cells and maintenance of tissue integrity. Thereby, anoikis serves as a potential molecular barrier against oncogenic transformation of normal cells. Cancer cells acquire anoikis resistance for survival and distant metastatic progression. During the acquisition of anoikis resistance, tumors modulate multiple cell signaling parameters through changes in the expression of up-stream receptors and by dynamically calibrating the dependency on down-stream signaling cascades. Many compounds that target the tumor-acquired switches in integrins, tumor antigens, growth factors, metabolic pathways, oxidative and osmotic-stress signaling are in various phases of pre-clinical and clinical development. Combinatorial approaches maximize the therapeutic efficacy and minimize the activation of alternate signaling pathways, which will otherwise contribute to drug resistance. In this regard, an integrated analysis of the mechanisms of action of potential drugs and lead compounds that can target significant nodes of anoikis signaling networks will provide a rational frame-work for further development and clinical use of respective agents, by formulating more effective combinatorial therapies, in patients with distinct drug-sensitivity profiles.

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

AIM: To investigate the effects of integrin-linked kinase (ILK) on gastric cancer cells both in vitro and in vivo.

METHODS: ILK small interfering RNA (siRNA) was transfected into human gastric cancer BGC-823 cells and ILK expression was monitored by real-time quantitative polymerase chain reaction, Western blotting analysis and immunocytochemistry. Cell attachment, proliferation, invasion, microfilament dynamics and the secretion of vascular endothelial growth factor (VEGF) were also measured. Gastric cancer cells treated with ILK siRNA were subcutaneously transplanted into nude mice and tumor growth was assessed.

RESULTS: Both ILK mRNA and protein levels were significantly down-regulated by ILK siRNA in human gastric cancer cells. This significantly inhibited cell attachment, proliferation and invasion. The knockdown of ILK also disturbed F-actin assembly and reduced VEGF secretion in conditioned medium by 40% (P < 0.05). Four weeks after injection of ILK siRNA-transfected gastric cancer cells into nude mice, tumor volume and weight were significantly reduced compared with that of tumors induced by cells treated with non-silencing siRNA or by untreated cells (P < 0.05).

CONCLUSION: Targeting ILK with siRNA suppresses the growth of gastric cancer cells both in vitro and in vivo. ILK plays an important role in gastric cancer progression.

Particularly interesting cysteine- and histidine-rich protein in cardiac development and remodeling

Integrin-mediated cell-extracellular matrix interaction plays key roles in tissue morphogenesis and integrity. The Lin11-Isl-1-Mec-3 (LIM) domain-only particularly interesting cysteine- and histidine-rich (PINCH) protein functions as an adaptor essential for the assembly and function of the focal adhesion complex that links integrin signaling to the cytoskeleton and other intracellular signaling pathways and regulates diverse cellular processes such as cell adhesion, migration, growth, differentiation, and survival. Recent biochemical and genetic studies have greatly advanced our knowledge surrounding the molecular interactions and functions of each component of the focal adhesion complex and revealed a requirement for PINCH in early embryogenesis, in morphogenesis of the neural crest and cardiac outflow, and in myocardial growth and remodeling. In this review article, we will provide an overview of the current knowledge of the molecular interactions of PINCH with other components of focal adhesions, highlighting recent discoveries of the in vivo role of PINCH and discuss its potential implication for human heart disease.

Deltonin, a steroidal saponin, inhibits colon cancer cell growth in vitro and tumor growth in vivo via induction of apoptosis and antiangiogenesis

Deltonin, a steroidal saponin, isolated from Dioscorea zingiberensis Wright (DZW), has shown high-cytotoxic activity in cancer cells. However, its mechanisms and in vivo anti-cancer effects remain unknown. In the present study, we evaluated the effects and explored the anti-tumor mechanisms of deltonin on a panel of colon cancer cell lines and in a mouse model of murine colon cancer C26. Deltonin had more cytotoxic effect on C26 cells than 5-fluorouracil had, promoting dramatic G2-M phase arrest and apoptosis in C26 cells in a concentration-dependent manner; oral administration of deltonin significantly inhibited the tumor growth and prolonged survival of the tumor bearing mice. The deltonin treatment caused a noticeable apoptosis in tumor tissue, which associated with increased levels of Bax, activated caspase-3, caspase-9, and cleaved poly (ADPribose) polymerase, decreased pro-caspase-8, pro-caspase-9, Bcl-2 expression levels and extracellular signal-regulated kinase-1/2 activity; and dose-dependently inhibit angiogenesis. In conclusion, the findings in this study demonstrated that deltonin is an effective natural agent for cancer therapy, which may be mediated, in part, by induction of apoptosis, as well as involve mitogen-activated protein kinase pathways, and inhibition of angiogenesis.

Integrin signalling adaptors: not only figurants in the cancer story

Current evidence highlights the ability of adaptor (or scaffold) proteins to create signalling platforms that drive cellular transformation upon integrin-dependent adhesion and growth factor receptor activation. The understanding of the biological effects that are regulated by these adaptors in tumours might be crucial for the identification of new targets and the development of innovative therapeutic strategies for human cancer. In this Review we discuss the relevance of adaptor proteins in signalling that originates from integrin-mediated cell-extracellular matrix (ECM) adhesion and growth factor stimulation in the context of cell transformation and tumour progression. We specifically underline the contribution of p130 Crk-associated substrate (p130CAS; also known as BCAR1), neural precursor cell expressed, developmentally down-regulated 9 (NEDD9; also known as HEF1), CRK and the integrin-linked kinase (ILK)-pinch-parvin (IPP) complex to cancer, along with the more recently identified p140 Cas-associated protein (p140CAP; also known as SRCIN1).

Anti-angiogenic therapy induces integrin-linked kinase 1 up-regulation in a mouse model of glioblastoma

Background

In order to improve our understanding of the molecular pathways that mediate tumor proliferation and angiogenesis, and to evaluate the biological response to anti-angiogenic therapy, we analyzed the changes in the protein profile of glioblastoma in response to treatment with recombinant human Platelet Factor 4-DLR mutated protein (PF4-DLR), an inhibitor of angiogenesis.

Methodology/Principal Findings

U87-derived experimental glioblastomas were grown in the brain of xenografted nude mice, treated with PF4-DLR, and processed for proteomic analysis. More than fifty proteins were differentially expressed in response to PF4-DLR treatment. Among them, integrin-linked kinase 1 (ILK1) signaling pathway was first down-regulated but then up-regulated after treatment for prolonged period. The activity of PF4-DLR can be increased by simultaneously treating mice orthotopically implanted with glioblastomas, with ILK1-specific siRNA. As ILK1 is related to malignant progression and a poor prognosis in various types of tumors, we measured ILK1 expression in human glioblatomas, astrocytomas and oligodendrogliomas, and found that it varied widely; however, a high level of ILK1 expression was correlated to a poor prognosis.

Conclusions/Significance

Our results suggest that identifying the molecular pathways induced by anti-angiogenic therapies may help the development of combinaatorial treatment strategies that increase the therapeutic efficacy of angiogenesis inhibitors by association with specific agents that disrupt signaling in tumor cells.

Transcriptional regulation of the insulin signaling pathway genes by starvation and 20-hydroxyecdysone in the Bombyx fat body

Genetic studies in the fruitfly, Drosophila melanogaster, have uncovered a conserved insulin/insulin growth factor signaling (IIS) pathway that regulates nutrition-dependent growth rates of insects. From the silkworm, Bombyx mori, we have identified and characterized several key genes involved in the IIS pathway, including InR, IRS, PI3K110, PI3K60, PTEN, PDK, and Akt. Tissue distribution analysis showed that most of these genes were highly expressed in the fat body implying that the IIS pathway is functionally important within insect adipose tissue. Developmental profile studies revealed that the expression levels of InR, IRS, PI3K110, and PDK were elevated in the fat body during molting and pupation, periods when animals ceased feeding and hemolymph levels of 20-hydroxyecdysone (20E) were high. Starvation rapidly up-regulated the mRNA levels of these same genes in the fat body, while 20E slowly induced their transcription. We conclude that 20E slowly reduces food consumption and then indirectly induces a state of starvation resulting in the elevation of the mRNA levels of InR, IRS, PI3K110, and PDK in the Bombyx fat body during molting and pupation.

Integrin-linked kinase is a functional Mn2+-dependent protein kinase that regulates glycogen synthase kinase-3β (GSK-3beta) phosphorylation

Background

Integrin-linked kinase (ILK) is a highly evolutionarily conserved, multi-domain signaling protein that localizes to focal adhesions, myofilaments and centrosomes where it forms distinct multi-protein complexes to regulate cell adhesion, cell contraction, actin cytoskeletal organization and mitotic spindle assembly. Numerous studies have demonstrated that ILK can regulate the phosphorylation of various protein and peptide substrates in vitro, as well as the phosphorylation of potential substrates and various signaling pathways in cultured cell systems. Nevertheless, the ability of ILK to function as a protein kinase has been questioned because of its atypical kinase domain.

Methodology/Principal Findings

Here, we have expressed full-length recombinant ILK, purified it to >94% homogeneity, and characterized its kinase activity. Recombinant ILK readily phosphorylates glycogen synthase kinase-3 (GSK-3) peptide and the 20-kDa regulatory light chains of myosin (LC₂₀). Phosphorylation kinetics are similar to those of other active kinases, and mutation of the ATP-binding lysine (K220 within subdomain 2) causes marked reduction in enzymatic activity. We show that ILK is a Mn-dependent kinase (the K_m for MnATP is ∼150-fold less than that for MgATP).

Conclusions/Significance

Taken together, our data demonstrate that ILK is a bona fide protein kinase with enzyme kinetic properties similar to other active protein kinases.