Focal adhesion kinase overexpression and its impact on human osteosarcoma

Repurposing the diuretic benzamil as an anti-osteosarcoma agent that acts by suppressing integrin/FAK/STAT3 signalling and compromising mitochondrial function

Aims

Osteosarcoma is the most common primary bone malignancy among children and adolescents. We investigated whether benzamil, an amiloride analogue and sodium-calcium exchange blocker, may exhibit therapeutic potential for osteosarcoma in vitro.

Methods

MG63 and U2OS cells were treated with benzamil for 24 hours. Cell viability was evaluated with the MTS/PMS assay, colony formation assay, and flow cytometry (forward/side scatter). Chromosome condensation, the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay, cleavage of poly-ADP ribose polymerase (PARP) and caspase-7, and FITC annexin V/PI double staining were monitored as indicators of apoptosis. Intracellular calcium was detected by flow cytometry with Fluo-4 AM. The phosphorylation and activation of focal adhesion kinase (FAK) and signal transducer and activator of transcription 3 (STAT3) were measured by western blot. The expression levels of X-linked inhibitor of apoptosis protein (XIAP), B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra large (Bcl-xL), SOD1, and SOD2 were also assessed by western blot. Mitochondrial status was assessed with tetramethylrhodamine, ethyl ester (TMRE), and intracellular adenosine triphosphate (ATP) was measured with BioTracker ATP-Red Live Cell Dye. Total cellular integrin levels were evaluated by western blot, and the expression of cell surface integrins was assessed using fluorescent-labelled antibodies and flow cytometry.

Results

Benzamil suppressed growth of osteosarcoma cells by inducing apoptosis. Benzamil reduced the expression of cell surface integrins α5, αV, and β1 in MG63 cells, while it only reduced the expression of αV in U2OS cells. Benzamil suppressed the phosphorylation and activation of FAK and STAT3. In addition, mitochondrial function and ATP production were compromised by benzamil. The levels of anti-apoptotic proteins XIAP, Bcl-2, and Bcl-xL were reduced by benzamil. Correspondingly, benzamil potentiated cisplatin- and methotrexate-induced apoptosis in osteosarcoma cells.

Conclusion

Benzamil exerts anti-osteosarcoma activity by inducing apoptosis. In terms of mechanism, benzamil appears to inhibit integrin/FAK/STAT3 signalling, which triggers mitochondrial dysfunction and ATP depletion.

Pivotal role of IL-8 derived from the interaction between osteosarcoma and tumor-associated macrophages in osteosarcoma growth and metastasis via the FAK pathway

The prognosis of osteosarcoma (OS) has remained stagnant over the past two decades, requiring the exploration of new therapeutic targets. Cytokines, arising from tumor-associated macrophages (TAMs), a major component of the tumor microenvironment (TME), have garnered attention owing to their impact on tumor growth, invasion, metastasis, and resistance to chemotherapy. Nonetheless, the precise functional role of TAMs in OS progression requires further investigation. In this study, we investigated the interaction between OS and TAMs, as well as the contribution of TAM-produced cytokines to OS advancement. TAMs were observed to be more prevalent in lung metastases compared with that in primary tumors, suggesting their potential support for OS progression. To simulate the TME, OS and TAMs were co-cultured, and the cytokines resulting from this co-culture could stimulate OS proliferation, migration, and invasion. A detailed investigation of cytokines in the co-culture conditioned medium (CM) revealed a substantial increase in IL-8, establishing it as a pivotal cytokine in the process of enhancing OS proliferation, migration, and invasion through the focal adhesion kinase (FAK) pathway. In an in vivo model, co-culture CM promoted OS proliferation and lung metastasis, effects that were mitigated by anti-IL-8 antibodies. Collectively, IL-8, generated within the TME formed by OS and TAMs, accelerates OS proliferation and metastasis via the FAK pathway, thereby positioning IL-8 as a potential novel therapeutic target in OS.

Focal adhesion kinase (FAK): its structure, characteristics, and signaling in skeletal system

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase and distributes important regulatory functions in skeletal system. Mesenchymal stem cell (MSC) possesses significant migration and differentiation capacity, is an important source of distinctive bone cells production and a prominent bone development pathway. MSC has a wide range of applications in tissue bioengineering and regenerative medicine, and is frequently employed for hematopoietic support, immunological regulation, and defect repair, although current research is insufficient. FAK has been identified to cross-link with many other keys signaling pathways in bone biology and is considered as a fundamental "crossroad" on the signal transduction pathway and a "node" in the signal network to mediate MSC lineage development in skeletal system. In this review, we summarized the structure, characteristics, cellular signaling, and the interactions of FAK with other signaling pathways in the skeletal system. The discovery of FAK and its mediated molecules will lead to a new knowledge of bone development and bone construction as well as considerable potential for therapeutic use in the treatment of bone-related disorders such as osteoporosis, osteoarthritis, and osteosarcoma.

Roles of focal adhesion proteins in skeleton and diseases

The skeletal system, which contains bones, joints, tendons, ligaments and other elements, plays a wide variety of roles in body shaping, support and movement, protection of internal organs, production of blood cells and regulation of calcium and phosphate metabolism. The prevalence of skeletal diseases and disorders, such as osteoporosis and bone fracture, osteoarthritis, rheumatoid arthritis, and intervertebral disc degeneration, increases with age, causing pain and loss of mobility and creating a huge social and economic burden globally. Focal adhesions (FAs) are macromolecular assemblies that are composed of the extracellular matrix (ECM), integrins, intracellular cytoskeleton and other proteins, including kindlin, talin, vinculin, paxillin, pinch, Src, focal adhesion kinase (FAK) and integrin-linked protein kinase (ILK) and other proteins. FA acts as a mechanical linkage connecting the ECM and cytoskeleton and plays a key role in mediating cell-environment communications and modulates important processes, such as cell attachment, spreading, migration, differentiation and mechanotransduction, in different cells in skeletal system by impacting distinct outside-in and inside-out signaling pathways. This review aims to integrate the up-to-date knowledge of the roles of FA proteins in the health and disease of skeletal system and focuses on the specific molecular mechanisms and underlying therapeutic targets for skeletal diseases.

ptk2 and mt2a Genes Expression in Gastritis and Gastric Cancer Patients with Helicobacter pylori Infection

BACKGROUND

ptk2 and mt2a genes contribute to the cell cycle during proliferation and apoptosis, respectively. Designing a case-control study including gastric adenocarcinoma and gastritis patients with and without Helicobacter pylori infection would lead to determinate of the correlations between ptk2 and mt2a genes expression with H. pylori infection in gastric antral epithelial cells.

METHODS

Overall, 50 and 30 gastric antral biopsy samples of gastric cancer (case group) and gastritis (control group) patients were included into study, respectively. All biopsy samples were collected considering the exclusion criteria including patients with a history of consumption of tobacco, alcohol, and anti-H. pylori drugs. Each patient group is divided into with and without H. pylori infection to detect cDNA fold changes of ptk2 and mt2a genes by using Real Time RT PCR. Furthermore, the presence of H. pylori virulence genes was detected directly by using specific primers and simple PCR on cDNA synthesized from total RNA of gastric antral biopsy samples.

RESULTS

A negative correlation was revealed between age and clinical manifestations with the ΔCt value of the ptk2 gene (P < 0.05). The H. pylori iceA1/2 and cagE genes revealed positive and negative correlations with the ΔCt value of the ptk2 gene (P < 0.05), respectively. Furthermore, a weak correlation was detectable between H. pylori babA2/B, oipA, and cagY genes and the ΔCt value of the mt2a gene in gastric antral epithelial cells of patients (P < 0.1).

CONCLUSIONS

The results of the current study opened a view for more investigation on the stunning roles of H. pylori infection in clinical outcomes through mt2a and ptk2 gene expression in gastric antral epithelial cells.

ERK phosphorylation is dependent on cell adhesion in a subset of pediatric sarcoma cell lines

Osteosarcoma (OS) and Pax-Foxo1 fusion negative rhabdomyosarcoma (FN-RMS) are pediatric sarcomas with poor prognoses in patients with advanced disease. In both malignancies, an actin binding protein has been linked to poor prognosis. Integrin adhesion complexes (IACs) are closely coupled to actin networks and IAC-mediated signaling has been implicated in the progression of carcinomas. However, the relationship of IACs and actin cytoskeleton remodeling with cell signaling is understudied in pediatric sarcomas. Here, we tested the hypothesis that IAC dynamics affect ERK activation in OS and FN-RMS cell lines. Adhesion dependence of ERK activation differed among the OS and FN-RMS cells examined. In the OS cell lines, adhesion did not have a consistent effect on phospho-ERK (pERK). ERK phosphorylation in response to fetal calf serum or 1 ng/ml EGF was nearly as efficient in OS cell lines and one FN-RMS cell line in suspension as cells adherent to poly-l-lysine (PL) or fibronectin (FN). By contrast, adhesion to plastic, PL or FN increased ERK phosphorylation and was greater than additive with a 15 min exposure to 1 ng/ml EGF in three FN-RMS cell lines. Increases in pERK were partly dependent on FAK and PAK1/2 but independent of IAC maturation. As far as we are aware, this examination of adhesion-dependent signaling is the first in pediatric sarcomas and has led to the discovery of differences from the prevailing paradigms and differences in the degree of coupling between components in the signaling pathways among the cell lines.

LOX upregulates FAK phosphorylation to promote metastasis in osteosarcoma

Osteosarcoma is a malignant bone tumor that commonly occurs in the pediatric population. Despite the use of chemotherapy and surgery, metastasis remains to be the leading cause of death in patients with osteosarcoma. We have previously reported that cytoplasmic mislocalization of p27 is associated with a poor outcome in osteosarcoma. In this study, we further show that lysyl oxidase (LOX) expression was associated with p27 mislocalization. LOX is an enigmatic molecule that acts as a tumor suppressor or a metastatic promoter; however, its role in osteosarcoma is still unclear. Hence, we performed both in vitro and in vivo analyses to dissect the role of LOX in osteosarcoma. The result of our survival analysis indicated that LOX expression significantly correlated with a poor outcome in osteosarcoma with or without controlling for the initial metastasis status (P < 0.05). Functionally, we found that higher LOX expression promoted osteosarcoma cell proliferation, migration, and invasiveness in vitro and produced a higher number of mice with pulmonary metastases in an orthotopic xenograft mouse model. Mechanistically, phospho-FAK was increased in osteosarcoma cells with high LOX expression. Our results further showed that FAK inhibition significantly reduced tumor cell proliferation and migration in vitro as well as LOX-mediated metastasis in mice. Together, our findings suggest that there is a novel link between p27 mislocalization and LOX expression. LOX plays a pivotal role in osteosarcoma metastasis by upregulating FAK phosphorylation. FAK inhibition may constitute a promising therapeutic strategy to reduce the development of metastasis in osteosarcoma with LOX overexpression.

Gangliosides as Signaling Regulators in Cancer

At the plasma membrane, gangliosides, a group of glycosphingolipids, are expressed along with glycosphingolipids, phospholipids, and cholesterol in so-called lipid rafts that interact with signaling receptors and related molecules. Most cancers present abnormalities in the intracellular signal transduction system involved in tumor growth, invasion, and metastasis. To date, the roles of gangliosides as regulators of signal transduction have been reported in several cancer types. Gangliosides can be expressed by the exogenous ganglioside addition, with their endogenous expression regulated at the enzymatic level by targeting specific glycosyltransferases. Accordingly, the relationship between changes in the composition of cell surface gangliosides and signal transduction has been investigated by controlling ganglioside expression. In cancer cells, several types of signaling molecules are positively or negatively regulated by ganglioside expression levels, promoting malignant properties. Moreover, antibodies against gangliosides have been shown to possess cytotoxic effects on ganglioside-expressing cancer cells. In the present review, we highlight the involvement of gangliosides in the regulation of cancer cell signaling, and we explore possible therapies targeting ganglioside-expressing cancer.

Cold Atmospheric Plasma: A New Strategy Based Primarily on Oxidative Stress for Osteosarcoma Therapy

Osteosarcoma is the most common primary bone tumor, and its first line of treatment presents a high failure rate. The 5-year survival for children and teenagers with osteosarcoma is 70% (if diagnosed before it has metastasized) or 20% (if spread at the time of diagnosis), stressing the need for novel therapies. Recently, cold atmospheric plasmas (ionized gases consisting of UV-Vis radiation, electromagnetic fields and a great variety of reactive species) and plasma-treated liquids have been shown to have the potential to selectively eliminate cancer cells in different tumors through an oxidative stress-dependent mechanism. In this work, we review the current state of the art in cold plasma therapy for osteosarcoma. Specifically, we emphasize the mechanisms unveiled thus far regarding the action of plasmas on osteosarcoma. Finally, we review current and potential future approaches, emphasizing the most critical challenges for the development of osteosarcoma therapies based on this emerging technique.

Three-dimensional decellularized tumor extracellular matrices with different stiffness as bioengineered tumor scaffolds

In the three-dimensional (3D) tumor microenvironment, matrix stiffness is associated with the regulation of tumor cells behaviors. In vitro tumor models with appropriate matrix stiffness are urgently desired. Herein, we prepare 3D decellularized extracellular matrix (DECM) scaffolds with different stiffness to mimic the microenvironment of human breast tumor tissue, especially the matrix stiffness, components and structure of ECM. Furthermore, the effects of matrix stiffness on the drug resistance of human breast cancer cells are explored with these developed scaffolds as case studies. Our results confirm that DECM scaffolds with diverse stiffness can be generated by tumor cells with different lysyl oxidase (LOX) expression levels, while the barely intact structure and major components of the ECM are maintained without cells. This versatile 3D tumor model with suitable stiffness can be used as a bioengineered tumor scaffold to investigate the role of the microenvironment in tumor progression and to screen drugs prior to clinical use to a certain extent.

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Novel 3D bioengineered tumor scaffolds with different stiffness were developed.

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Cells with different LOX expression levels were used to generate tumor tissue.

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DECM scaffold has good cytocompatibility.

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DECM with high stiffness promotes the resistance of MDA-MB-231 cells to cisplatin.

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DECM with high stiffness increases the expression of Bcl-2 and ABCB1.

Obacunone protects retinal pigment epithelium cells from ultra-violet radiation-induced oxidative injury

Ultra-violet (UV) radiation (UVR) causes significant oxidative injury to retinal pigment epithelium (RPE) cells. Obacunone is a highly oxygenated triterpenoid limonoid compound with various pharmacological properties. Its potential effect in RPE cells has not been studied thus far. Here in ARPE-19 cells and primary murine RPE cells, obacunone potently inhibited UVR-induced reactive oxygen species accumulation, mitochondrial depolarization, lipid peroxidation and single strand DNA accumulation. UVR-induced RPE cell death and apoptosis were largely alleviated by obacunone. Obacunone activated Nrf2 signaling cascade in RPE cells, causing Keap1-Nrf2 disassociation, Nrf2 protein stabilization and nuclear translocation. It promoted transcription and expression of antioxidant responsive element-dependent genes. Nrf2 silencing or CRISPR/Cas9-induced Nrf2 knockout almost reversed obacunone-induced RPE cytoprotection against UVR. Forced activation of Nrf2 cascade, by Keap1 knockout, similarly protected RPE cells from UVR. Importantly, obacunone failed to offer further RPE cytoprotection against UVR in Keap1-knockout cells. In vivo, intravitreal injection of obacunone largely inhibited light-induced retinal damage. Collectively, obacunone protects RPE cells from UVR-induced oxidative injury through activation of Nrf2 signaling cascade.

Graphene oxide nanofilm and chicken embryo extract decrease the invasiveness of HepG2 liver cancer cells

Background

The extracellular matrix (ECM) is a mosaic of various structural and functional proteins that cooperate with the cell, regulate adhesion, and consequently manage its further fate. Liver destruction is accompanied by a disruption of the physicochemical properties of the ECM which deregulates the cell–ECM interaction and can lead to uncontrolled proliferation and neoplastic transformation of cells. Therefore, it can be assumed that ECM modification and restoration of its characteristics for healthy tissue may counteract uncontrolled cell proliferation. The purpose of the presented research model was to optimise the physical characteristics of ECM by introducing a graphene oxide plane/nanofilm (nfGO) and enriching the cell environment with potentially missing proteins by adding a functional protein cocktail (chicken embryo liver extract) and determine the impact of these factors on cell–ECM cooperation and its consequences on adhesion, proliferation, and cell phase, which are factors of the invasiveness of cancer cells.

Results

Experiments were performed with non-cancer HS-5 cells and liver cancer cells HepG2 and C3A. The cells were divided into four groups: (1) control, (2) cultured on nfGO, (3) cultured with the addition of chicken embryo liver extract (CELE) and (4) cultured on the nfGO with the addition of CELE. CELE contained 1735 proteins; the top 57 of these proteins have been presented. The use of nfGO as well as CELE and nfGO + CELE reduced the proliferation of HepG2 cancer cells to the greatest extent; this is in contrast to non-cancer cells and also to C3A cancer cells. Furthermore, the combined use of the CELE protein cocktail and GO substrate effectively resulted in a decrease in the population of HepG2 cells in the G0/G1 phase and an increase of the population in G2/M. Molecular analysis of HepG2 cancer cells also showed an increase in the expression of genes responsible for adhesion such as focal adhesion kinase (fak), e-cadherin, and n-cadherin and a decrease in β-catenin, which is considered a proto-oncogene.

Conclusions

Studies have shown that both the GO surface structure on which the cells are grown as well as the presence of a multi-component natural cocktail of regulatory proteins, can modify the expression of integrins, increase adhesion and, as a consequence, proliferation and the cell cycle—entering the resting phase. For the first time, it has been documented that hepatic cancer cells of the HepG2 line under the influence of stimuli derived from mimic ECM (graphene oxide) in interaction with a unique protein complex derived from chicken liver embryo decreased of the invasiveness of cancer cells.

Role of Focal Adhesion Kinase in Small-Cell Lung Cancer and Its Potential as a Therapeutic Target

Small-cell lung cancer (SCLC) represents 15% of all lung cancers and it is clinically the most aggressive type, being characterized by a tendency for early metastasis, with two-thirds of the patients diagnosed with an extensive stage (ES) disease and a five-year overall survival (OS) as low as 5%. There are still no effective targeted therapies in SCLC despite improved understanding of the molecular steps leading to SCLC development and progression these last years. After four decades, the only modest improvement in OS of patients suffering from ES-SCLC has recently been shown in a trial combining atezolizumab, an anti-PD-L1 immune checkpoint inhibitor, with carboplatin and etoposide, chemotherapy agents. This highlights the need to pursue research efforts in this field. Focal adhesion kinase (FAK) is a non-receptor protein tyrosine kinase that is overexpressed and activated in several cancers, including SCLC, and contributing to cancer progression and metastasis through its important role in cell proliferation, survival, adhesion, spreading, migration, and invasion. FAK also plays a role in tumor immune evasion, epithelial-mesenchymal transition, DNA damage repair, radioresistance, and regulation of cancer stem cells. FAK is of particular interest in SCLC, being known for its aggressiveness. The inhibition of FAK in SCLC cell lines demonstrated significative decrease in cell proliferation, invasion, and migration, and induced cell cycle arrest and apoptosis. In this review, we will focus on the role of FAK in cancer cells and their microenvironment, and its potential as a therapeutic target in SCLC.

Increased Expression and Activation of FAK in Small-Cell Lung Cancer Compared to Non-Small-Cell Lung Cancer

INTRODUCTION

Focal adhesion kinase (FAK) plays a crucial role in cancer development and progression. FAK is overexpressed and/or activated and associated with poor prognosis in various malignancies. However, in lung cancer, activated FAK expression and its prognostic value are unknown.

METHODS

FAK and activated FAK (phospho-FAK Y397) expressions were analyzed by multiplex immunofluorescence staining in formalin-fixed paraffin-embedded tissues from 95 non-small-cell lung cancer (NSCLC) and 105 small-cell lung cancer (SCLC) patients, and 37 healthy donors. The FAK staining score was defined as the percentage (%) of FAK-stained tumor area multiplied by (×) FAK mean intensity and phospho-FAK staining score as the (% of phospho-FAK-stained area of low intensity × 1) + (% of phospho-FAK-stained area of medium intensity × 2) + (% of the phospho-FAK-stained area of high intensity × 3). FAK and phospho-FAK staining scores were compared between normal, NSCLC, and SCLC tissues. They were also tested for correlations with patient characteristics and clinical outcomes.

RESULTS

The median follow-up time after the first treatment was 42.5 months and 6.4 months for NSCLC and SCLC patients, respectively. FAK and phospho-FAK staining scores were significantly higher in lung cancer than in normal lung and significantly higher in SCLC compared to NSCLC tissues (p < 0.01). Moreover, the ratio between phospho-FAK and FAK staining scores was significantly higher in SCLC than in NSCLC tissues (p < 0.01). However, FAK and activated FAK expression in lung cancer did not correlate with recurrence-free and overall survival in NSCLC and SCLC patients.

CONCLUSIONS

Total FAK and activated FAK expressions are significantly higher in lung cancer than in normal lung, and significantly higher in SCLC compared to NSCLC, but are not prognostic biomarkers in this study.

Potential Molecular Mechanisms of AURKB in the Oncogenesis and Progression of Osteosarcoma Cells: A Label-Free Quantitative Proteomics Analysis

Our previous study indicated that knockdown of Aurora-B inhibit the proliferation of osteosarcoma cells. But the function and molecular mechanisms of Aurora-B in osteosarcoma cells growth and metastasis remains unclear. The aim of this study was to investigate the molecular mechanisms of Aurora-B in the progression of osteosarcoma. Osteosarcoma cells (U2-OS and 143B) were treated with specific Lentivirus-Vectors (up or downregulation Aurora-B). The ability of cells proliferation, migration, and invasion was measured using Cell-Counting Kit-8, wound healing and transwell invasion assays. Furthermore, based on label-free quantitative proteomic analysis of potential molecular mechanisms of Aurora-B in human 143B cells. A total of 25 downregulated and 76 upregulated differentially expressed proteins were screened in terms of the change in their expression abundance. We performed functional annotation and functional enrichment analyses. Gene ontology enrichment, KEGG analysis, and protein-protein interaction networks were constructed and analyzed. We found that the PTK2 may play an important role in the progression of osteosarcoma cells. Finally, Western blot revealed that expression of PTK2, AKT, PI3K, and nuclear factor-kappaB increased after over expression of Aurora-B. Overall, these data highlight that Aurora-B may promote the malignant phenotype of osteosarcoma cells by activating the PTK2/PI3K/AKt/nuclear factor-KappaB pathway.

Migration-inducing gene-7 independently predicts poor prognosis of human osteosarcoma and is associated with vasculogenic mimicry

Vasculogenic mimicry (VM) is a special type of vascular channel formed by tumor cells without endothelial cell participation. Migration-inducing gene 7 (MIG-7) plays an important role in regulating VM. In this study, immunohistochemical staining was used to detect MIG-7 in tissue specimens from 141 primary osteosarcoma patients, and the relationship between MIG-7 and VM was examined. Survival analysis were performed to evaluate the prognoses. MIG-7 knockdown osteosarcoma cells were used for cell proliferation, apoptosis, migration, invasiveness and VM formation assays. A spontaneously metastasizing cell line-derived orthotopic xenograft mouse model was established to evaluate the effect of MIG-7 knockdown on tumorigenesis, VM formation and lung metastasis. MIG-7 expression was associated with VM formation. There were significant differences in overall and metastasis-free survival between the MIG-7-positive and MIG-7-negative groups. The MIG-7 expression was shown to be an independent indicator of both overall and metastasis-free survival. In vitro knockdown of MIG-7 dramatically reduced migration, invasion and VM formation in osteosarcoma cells without any significant effect on cell proliferation and apoptosis. MIG-7 knockdown also exhibited potent antitumor, antimetastasis and anti-VM effects in the orthotopic mouse model of 143B osteosarcoma. Therefore, MIG-7 serves as an independent unfavorable prognostic indicator in osteosarcoma patients and MIG-7 is an important mediator of osteosarcoma VM formation.

mir-218-2 promotes glioblastomas growth, invasion and drug resistance by targeting CDC27

Glioma has become a significant global health problem with substantial morbidity and mortality, underscoring the importance of elucidating its underlying molecular mechanisms. Recent studies have identified mir-218 as an anti-oncogene; however, the specific functions of mir-218-1 and mir-218-2 remain unknown, especially the latter. The objective of this study was to further investigate the role of mir-218-2 in glioma. Our results indicated that mir-218-2 is highly overexpressed in glioma. Furthermore, we showed that mir-218-2 is positively correlated with the growth, invasion, migration, and drug susceptibility (to β-lapachone) of glioma cells. In vitro, the overexpression of mir-218-2 promoted glioma cell proliferation, invasion, and migration. In addition, the overexpression of mir-218-2 in vivo was found to increase glioma tumor growth. Accordingly, the inhibition of mir-218-2 resulted in the opposite effects. Cell division cycle 27 (CDC27), the downstream target of mir-218-2, is involved in the regulation of glioma cells. Our results indicate that the overexpression of CDC27 counteracted the function of mir-218-2 in glioma cells. These novel findings provide new insight in the application of mir-218-2 as a potential glioma treatment.

FUS-CHOP Promotes Invasion in Myxoid Liposarcoma through a SRC/FAK/RHO/ROCK-Dependent Pathway

Deregulated SRC/FAK signaling leads to enhanced migration and invasion in many types of tumors. In myxoid and round cell liposarcoma (MRCLS), an adipocytic tumor characterized by the expression of the fusion oncogene FUS-CHOP, SRC have been found as one of the most activated kinases. Here we used a cell-of-origin model of MRCLS and an MRCLS cell line to thoroughly characterize the mechanisms of cell invasion induced by FUS-CHOP using in vitro (3D spheroid invasion assays) and in vivo (chicken chorioallantoic membrane model) approaches. FUS-CHOP expression activated SRC-FAK signaling and increased the invasive ability of MRCLS cells. In addition, FAK expression was found to significantly correlate with tumor aggressiveness in sarcoma patient samples. The involvement of SRC/FAK activation in FUS-CHOP-mediated invasion was further confirmed using the SRC inhibitor dasatinib, the specific FAK inhibitor PF-573228, and FAK siRNA. Notably, dasatinib and PF573228 could also efficiently block the invasion of cancer stem cell subpopulations. Downstream of SRC/FAK signaling, we found that FUS-CHOP expression increases the levels of the RHO/ROCK downstream effector phospho-MLC2 (T18/S19) and that this activation was prevented by dasatinib or PF573228. Moreover, the ROCK inhibitor RKI-1447 was able to completely abolish invasion in FUS-CHOP-expressing cells. These data uncover the involvement of SRC/FAK/RHO/ROCK signaling axis in FUS-CHOP-mediated invasion, thus providing a rationale for testing inhibitors of this pathway as potential novel antimetastatic agents for MRCLS treatment.

MIND4-17 protects retinal pigment epithelium cells and retinal ganglion cells from UV

Nrf2 activation would efficiently protect retinal cells from UV radiation (UVR). Recent studies have developed a Nrf2-targeting thiazole-containing compound MIND4-17, which activates Nrf2 through blocking its association with Keap1. In the current study, we demonstrated that pretreatment with MIND4-17 efficiently protected retinal pigment epithelium (RPE) cells (RPEs) and retinal ganglion cells (RGCs) from UVR. UVR-induced apoptosis in the retinal cells was also largely attenuated by MIND4-17 pretreatment. MIND4-17 presumably separated Nrf2 from Keap1, allowing its stabilization and accumulation in retinal cells, which then translocated to cell nuclei and promoted transcription of ARE-dependent anti-oxidant genes, including HO1, NQO1 and GCLM. Significantly, shRNA-mediated knockdown of Nrf2 almost completely abolished MIND4-17-induced cytoprotection against UVR. Further studies showed that MIND4-17 largely ameliorated UVR-induced ROS production, lipid peroxidation and DNA damages in RPEs and RGCs. Together, MIND4-17 protects retinal cells from UVR by activating Nrf2 signaling.

pFAK-Y397 overexpression as both a prognostic and a predictive biomarker for patients with metastatic osteosarcoma

Focal adhesion kinase (FAK) is important for tumor cell survival and metastasis in various cancers. However, its expression and prognostic value in patients with metastatic osteosarcoma remain unknown. We investigated the expression of FAK and its phosphorylated form (pFAK-Y397) in osteosarcoma tissues from 53 patients by immunohistochemistry and evaluated their correlations with clinicopathologic characteristics and outcomes. The prognostic values were assessed using Kaplan-Meier survival and Cox regression analyses. Total FAK and pFAK-Y397 were overexpressed in 48 (90.6%) and 33 (62.3%) cases, respectively. pFAK-Y397 overexpression was correlated with poor histologic response after neoadjuvant chemotherapy in patients with osteosarcoma regardless of the presence of metastasis or not. Kaplan-Meier curve showed that patients with metastatic osteosarcoma with pFAK-Y397 overexpression had significantly worse overall survival (OS) than those with non-overexpression (P = 0.044). Multivariate Cox regression analysis confirmed pFAK-Y397 overexpression as an independent prognostic predictor for OS and post metastases OS (PMOS) (P = 0.017, P = 0.006, respectively). Age at diagnosis was also an independent indicator for PMOS (P = 0.003). However, total FAK expression was not correlated with any clinicopathologic characteristics or OS in patients with metastatic osteosarcoma. In conclusion, our findings identified FAK as a common aberrant protein overexpression in various subtypes of osteosarcoma. pFAK-Y397 overexpression can be used as a prognostic biomarker predicting poor OS for patients with metastatic osteosarcoma, and the expression of pFAK-Y397 differentiated good and poor responders to neoadjuvant chemotherapy.

Antitumor effect of focal adhesion kinase inhibitor PF562271 against human osteosarcoma in vitro and in vivo

Focal adhesion kinase (FAK) overexpression is related to invasive and metastatic properties in different kinds of cancers. Target therapy by inhibiting FAK has achieved promising effect in some cancer treatments, but its effect in human osteosarcoma has not been well studied. In the present study, we analyzed the antitumor efficacy of PF562271, an FAK inhibitor, against osteosarcoma in vitro and in vivo. Phosphorylated FAK (Y397) was highly expressed in primary human osteosarcoma tumor samples and was associated with osteosarcoma prognosis and lung metastasis. PF562271 greatly suppressed proliferation and colony formation in human osteosarcoma cell lines. In addition, treatment of osteosarcoma cell lines with PF562271 induced apoptosis and downregulated the activity of the protein kinase B/mammalian target of rapamycin pathway. PF562271 also impaired the tube formation ability of endothelial cells in vitro. Finally, oral treatment with PF562271 in mice dramatically reduced tumor volume, weight, and angiogenesis of osteosarcoma xenografts in vivo. These results indicate that FAK inhibitor PF562271 can potentially be effectively used for the treatment of osteosarcoma.

Thrombospondin-1 promotes cell migration, invasion and lung metastasis of osteosarcoma through FAK dependent pathway

Microenvironment at the metastatic locus usually differs greatly from that present in the site of primary tumor formation and it has a significant impact on the fate of the extravasated cancer cells. We compared gene expression signatures of primary tumors and lung metastatic tumors, and identified Thrombospondin-1 (TSP1) as highly up-regulated in the lung metastatic tumors. Immunohistochemical staining further indicated that TSP1 protein expression was higher in lung metastatic tumors compared to primary tumors in both osteosarcoma xenograft model and human clinical samples. TSP1 mRNA level is significantly associated with the Enneking stage of osteosarcoma and lung metastasis. TGF-β pathways could stimulate the TSP1 expression in osteosarcoma cells. Knockdown of TSP1 expression in osteosarcoma cells dramatically suppressed cell wound healing, migration and invasion. Treatment with recombinant TSP1 protein in osteosarcoma cells significantly promoted cell wound healing, migration and invasion. Meanwhile, suppression of TSP1 in osteosarcoma cells resulted in decreased pulmonary metastasis in vivo. Mechanistically, TSP1 increased expression of metastasis related genes, including MMP2, MMP9 and Fibronectin 1. TSP1 promoted osteosarcoma cell motility through the activation of FAK pathway. Taken together, our study provides evidence of the contributions of TSP1 to the lung metastasis of osteosarcoma and suggests that this protein may represent a potential therapeutic target for osteosarcoma lung metastasis.

Paris polyphylla Suppresses Proliferation and Vasculogenic Mimicry of Human Osteosarcoma Cells and Inhibits Tumor Growth In Vivo

Paris polyphylla, a traditional antipyretic-detoxicate chinese medicinal herb, has been applied extensively in cancer treatments for nearly 2000 years. The purpose of the present study is to evaluate the potential anti-osteosarcoma effects of Paris polyphylla ethanol extract (PPEE) and to investigate its underlying mechanisms. The antiproliferation activity of PPEE was tested on 143B, MG-63, U-2 OS and hFOB1.19 cells using MTT assay. The pro-apoptotic and cell cycle arrest effects of PPEE were confirmed by Hoechst 33342 staining and flow cytometry. The antimigratory, anti-invasive and antivasculogenic mimicry (VM) effects of PPEE were investigated by wound healing, Transwell and 3D culture assays. Mouse xenograft model was used to examine its anti-osteosarcoma efficacy in vivo. Hematologic profiles and hepatorenal functions were evaluated to assess the toxicity of PPEE. PPEE evidently suppressed cell proliferation of 143B, MG-63 and U-2 OS with IC50 values of 10-60[Formula: see text][Formula: see text]g/mL, but showed little cytotoxicity against normal osteoblastic cell. PPEE promoted apoptosis in 143B cell via caspase activation, increased Bax/Bcl-2 ratio and PARP cleavage. It also induced G2/M phase arrest associated with elevated phosphorylation of CDK1, Cdc25C, Chk2 and down-regulation of cyclin B1, CDK1, Cdc25C expression. Additionally, PPEE inhibited 143B cell migration, invasion and VM formation at noncytotoxic concentrations through decreasing the expression of FAK, Mig-7, MMP2 and MMP9. Finally, daily oral administration of PPEE for four weeks exhibits potent antitumor and anti-VM activity in 143B xenograft model with low toxicity. Taken together, these findings demonstrated PPEE possesses anti-osteosarcoma and anti-VM activity in vitro and in vivo, and therefore is a potential candidate for osteosarcoma treatment.

Mesenchymal Stem/Stromal Cells under Stress Increase Osteosarcoma Migration and Apoptosis Resistance via Extracellular Vesicle Mediated Communication

Studies have shown that mesenchymal stem/stromal cells (MSCs) from bone marrow are involved in the growth and metastasis of solid tumors but the mechanism remains unclear in osteosarcoma (OS). Previous studies have raised the possibility that OS cells may receive support from associated MSCs in the nutrient deprived core of the tumors through the release of supportive macromolecules and growth factors either in vesicular or non-vesicular forms. In the present study, we used stressed mesenchymal stem cells (SD-MSCs), control MSCs and OS cells to examine the hypothesis that tumor-associated MSCs in nutrient deprived core provide pro-proliferative, anti-apoptotic, and metastatic support to nearby tumor cells. Assays to study of the effects of SD-MSC conditioned media revealed that OS cells maintained proliferation when compared to OS cells grown under serum-starved conditions alone. Furthermore, OS cells in MSCs and SD-MSC conditioned media were significantly resistant to apoptosis and an increased wound healing rate was observed in cells exposed to either conditioned media or EVs from MSCs and SD-MSCs. RT-PCR assays of OS cells incubated with extracellular vesicles (EVs) from SD-MSCs revealed microRNAs that could potentially target metabolism and metastasis associated genes as predicted by in silico algorithms, including monocarboxylate transporters, bone morphogenic receptor type 2, fibroblast growth factor 7, matrix metalloproteinase-1, and focal adhesion kinase-1. Changes in the expression levels of focal adhesion kinase, STK11 were confirmed by quantitative PCR assays. Together, these data indicate a tumor supportive role of MSCs in osteosarcoma growth that is strongly associated with the miRNA content of the EVs released from MSCs under conditions that mimic the nutrient deprived core of solid tumors.

Targeting Focal Adhesion Kinase Suppresses the Malignant Phenotype in Rhabdomyosarcoma Cells

Despite the tremendous advances in the treatment of childhood solid tumors, rhabdomyosarcoma (RMS) continues to provide a therapeutic challenge. Children with metastatic or relapsed disease have a disease-free survival rate under 30%. Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that is important in many facets of tumorigenesis. Signaling pathways both upstream and downstream to FAK have been found to be important in sarcoma tumorigenesis, leading us to hypothesize that FAK would be present in RMS and would impact cellular survival. In the current study, we showed that FAK was present and phosphorylated in pediatric alveolar and embryonal RMS tumor specimens and cell lines. We also examined the effects of FAK inhibition upon two RMS cell lines utilizing parallel approaches including RNAi and small molecule inhibitors. FAK inhibition resulted in decreased cellular survival, invasion, and migration and increased apoptosis. Furthermore, small molecule inhibition of FAK led to decreased tumor growth in a nude mouse RMS xenograft model. The findings from this study will help to further our understanding of the regulation of tumorigenesis in RMS and may provide desperately needed novel therapeutic strategies for these difficult-to-treat tumors.