Alteration in metastasis potential and gene expression in human lung cancer cell lines by ITGB8 silencing

Pericardial delta like non-canonical NOTCH ligand 1 (Dlk1) augments fibrosis in the heart through epithelial to mesenchymal transition

BACKGROUND

Heart failure due to myocardial infarction (MI) involves fibrosis driven by epicardium-derived cells (EPDCs) and cardiac fibroblasts, but strategies to inhibit and provide cardio-protection remains poor. The imprinted gene, non-canonical NOTCH ligand 1 (Dlk1), has previously been shown to mediate fibrosis in the skin, lung and liver, but very little is known on its effect in the heart.

METHODS

Herein, human pericardial fluid/plasma and tissue biopsies were assessed for DLK1, whereas the spatiotemporal expression of Dlk1 was determined in mouse hearts. The Dlk1 heart phenotype in normal and MI hearts was assessed in transgenic mice either lacking or overexpressing Dlk1. Finally, in/ex vivo cell studies provided knowledge on the molecular mechanism.

RESULTS

Dlk1 was demonstrated in non-myocytes of the developing human myocardium but exhibited a restricted pericardial expression in adulthood. Soluble DLK1 was twofold higher in pericardial fluid (median 45.7 [34.7 (IQR)) μg/L] from cardiovascular patients (n = 127) than in plasma (median 26.1 μg/L [11.1 (IQR)]. The spatial and temporal expression pattern of Dlk1 was recapitulated in mouse and rat hearts. Similar to humans lacking Dlk1, adult Dlk1-/- mice exhibited a relatively mild developmental, although consistent cardiac phenotype with some abnormalities in heart size, shape, thorax orientation and non-myocyte number, but were functionally normal. However, after MI, scar size was substantially reduced in Dlk1-/- hearts as compared with Dlk1+/+ littermates. In line, high levels of Dlk1 in transgenic mice Dlk1fl/fl xWT1GFPCre and Dlk1fl/fl xαMHCCre/+Tam increased scar size following MI. Further mechanistic and cellular insight demonstrated that pericardial Dlk1 mediates cardiac fibrosis through epithelial to mesenchymal transition (EMT) of the EPDC lineage by maintaining Integrin β8 (Itgb8), a major activator of transforming growth factor β and EMT.

CONCLUSIONS

Our results suggest that pericardial Dlk1 embraces a, so far, unnoticed role in the heart augmenting cardiac fibrosis through EMT. Monitoring DLK1 levels as well as targeting pericardial DLK1 may thus offer new venues for cardio-protection.

Establishment and validation of a novel integrin-based prognostic gene signature that sub-classifies gliomas and effectively predicts immunosuppressive microenvironment

The integrin family members play a key role in cancer immunomodulation and prognosis. We comprehensively analyzed the expression patterns and clinical significance of integrin family-related genes in gliomas. A total of 2293 gliomas from the Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA) and Gliovis platform were enrolled for analyses. Twenty-six integrin coding genes showed different expression patterns between glioma and normal brain tissues. We screened an integrin family-related gene signature (ITGA5, ITGA9, ITGAE, ITGB7 and ITGB8) that showed independent prognostic value and sub-classified gliomas into different prognostic and molecular clusters, further composed an integrin-based risk score model associated with glioma malignant clinical features, overall survival (OS), and immune microenvironment alterations. Besides, glioma patients with high-risk scores showed chemotherapeutic resistance and more immune cells infiltration as well as high immune checkpoints expression. Concurrently, we also revealed that high-risk score group presented resistance to T cell-mediated cancer killing process and lower rates of response to immune checkpoint blockade (ICB) treatment. In conclusion, our study identified a valuable integrin gene signature that predicted gliomas OS effectively, and sub-classified them into different phenotypes and accompanied with immunological changes, possibly acted as a biomarker for ICB treatment.

Baicalein Inhibits Metastatic Phenotypes in Nasopharyngeal Carcinoma Cells via a Focal Adhesion Protein Integrin β8

Baicalein, a prominent flavonoid from the indigenous herbal plant Scutellaria baicalensis Georgi, possesses broad-spectrum anticancer activities. However, the biological effects of baicalein on nasopharyngeal carcinoma (NPC) and its underlying mechanisms remain unclarified. Thus, in this study, we examined the effects of baicalein on NPC cell lines and investigated the corresponding molecular mechanism through transcriptome profiling. In the study, four NPC cell lines were treated with various concentrations of baicalein at different time points. Cellular toxicity and proliferative inhibition of baicalein were examined by MTT assay. Metastatic phenotypes of NPC cells were investigated by wound healing, transwell, and adhesion assays. Additionally, microarray experiments were performed to determine the cellular pathways affected by baicalein. The expression and localization of the integrin β8 were validated by western immunoblotting and immunofluorescence. Our results revealed that baicalein exhibited its cytotoxicity and antiproliferative activity on all tested NPC cell lines. It also significantly inhibited metastatic phenotypes at sub-lethal concentrations. Transcriptomic analysis showed that baicalein significantly affected the focal adhesion pathway in NPC, where integrin β8 was greatly diminished. Thus, the present study results suggested that baicalein inhibits the metastatic phenotypes of NPC cells by modulating integrin β8, one of the major molecules in a focal adhesion pathway.

LncRNA TCF7 Promotes Epithelial Ovarian Cancer Viability, Mobility and Stemness via Regulating ITGB8

This study aimed to investigate the carcinogenic role of long non-coding RNA T-cell factor 7 (lnc-TCF7) in epithelial ovarian cancer (EOC). Lnc-TCF7 overexpression and shRNA plasmids were transfected into SKOV3 and OVCAR3 cells, followed by measurement of cell proliferation, migration, invasion, apoptosis, stemness, and mRNA profile (via microarray). Besides, lnc-TCF7 expression was measured in tumor and adjacent tissues from 76 EOC patients. Lnc-TCF7 was upregulated in EOC cell lines; its overexpression increased cell proliferation, migration, invasion, but decreased apoptosis and promoted CD44, CD133 expressions, CD44+CD133+ cell proportion, spheres formation efficiency and drug resistance to cisplatin in SKOV3 and OVCAR3 cells. Besides, lnc-TCF7 ShRNA exhibited opposite effects comparing with its overexpression. Microarray analysis revealed 267 mRNAs were modulated by lnc-TCF7 dysregulation, among which ITGB8 was the most dysregulated one, which was validated by subsequent western blot and RT-qPCR. Furthermore, ITGB8 overexpression not only induced proliferation, migration, invasion and stemness, but also attenuated the effect of lnc-TCF7 ShRNA on these functions in SKOV3 and OVCAR3 cells. In addition, lnc-TCF7 was upregulated in tumor tissues and correlated with higher pathological grade, tumor size, International Federation of Gynecology and Obstetrics (FIGO) stage and worse overall survival in EOC patients. Conclusively, lnc-TCF7 regulates multiple oncogenic pathways, promotes proliferation, migration, invasion, stemness via upregulating ITGB8. It also correlates with advanced tumor features and poor prognosis in EOC, implying its potential as a target for EOC treatment.

Pancreatic Lineage Specifier PDX1 Increases Adhesion and Decreases Motility of Cancer Cells

Intercellular interactions involving adhesion factors are key operators in cancer progression. In particular, these factors are responsible for facilitating cell migration and metastasis. Strengthening of adhesion between tumor cells and surrounding cells or extracellular matrix (ECM), may provide a way to inhibit tumor cell migration. Recently, we demonstrated that PDX1 ectopic expression results in the reduction of pancreatic cancer line PANC-1 cell motility in vitro and in vivo, and we now provide experimental data confirming the hypothesis that suppression of migration may be related to the effect of PDX1 on cell adhesion. Cell migration analyses demonstrated decreased motility of pancreatic Colo357 and PANC-1 cell lines expressing PDX1. We observed decreased expression levels of genes associated with promoting cell migration and increased expression of genes negatively affecting cell motility. Expression of the EMT regulator genes was only mildly induced in cells expressing PDX1 during the simulation of the epithelial-mesenchymal transition (EMT) by the addition of TGFβ1 to the medium. PDX1-expressing cancer cell lines showed increased cell adhesion to collagen type I, fibronectin, and poly-lysine. We conclude that ectopic expression of PDX1 reduces the migration potential of cancer cells, by increasing the adhesive properties of cells and reducing the sensitivity to TGFβ1-induced EMT.

Expression and Prognostic Analysis of Integrins in Gastric Cancer

Background

Integrins are involved in the biological process of a variety of cancers, but their importance in the diagnosis and prognosis of gastric cancer (GC) is still unclear. Therefore, this study aimed at exploring the significance of ITG gene expression in GC to evaluate its diagnosis and prognosis.

Methods

GEPIA data were used to evaluate the mRNA expression of ITG genes in GC patients. The prognostic value of these genes was assessed by analyzing their mRNA expression using the Kaplan–Meier curve. The biological function of ITG genes was evaluated by GC tissue sequencing combined with GSEA bioinformatics. Based on the sequencing data, ITGA5 with the largest expression difference was selected for verification, and RT-PCR was used to verify its mRNA expression level in 40 pairs of GC and normal tissues.

Results

ITG (A2, A3, A4, A5, A6, A11, AE, AL, AM, AV, AX, B1, B2, B4, B5, B6, and B8) was highly expressed in GC tissues, while ITGA8 was low, compared with their expression in normal tissues. RNA-seq data shows that ITG (A2, A5, A11, AV, and B1) expression was associated with poor prognosis and overall survival. In addition, combined with the results of GC tissue mRNA sequencing, it was further found that the differentially expressed genes in the ITGs genes. ITGA5 was highly expressed in GC tissues compared with its expression in normal tissues, as evaluated by qRT–PCR (P < 0.001) and ROC (P < 0.001, AUC (95% CI) = 0.747 (0.641–0.851)), and confirmed that ITGA5 expression was a potential diagnostic marker for GC. Bioinformatics analysis revealed that the signaling pathway involved in ITGA5 was mainly enriched in focal adhesion, ECM-receptor interaction, and PI3K-AKT and was mainly involved in biological processes such as cell adhesion, extracellular matrix, and cell migration.

Conclusion

This study suggested that ITGs were associated with the diagnosis and prognosis of GC and discovered the prognostic value and biological role of ITGA5 in GC. Thus, ITGA5 might be used as a potential diagnostic marker for GC.

Coexisting EGFR and TP53 Mutations in Lung Adenocarcinoma Patients Are Associated With COMP and ITGB8 Upregulation and Poor Prognosis

The heterogeneity of lung adenocarcinoma is driven by key mutations in oncogenes. To determine the gene expression, single nucleotide polymorphisms, and co-mutations participating in the initiation and progression of lung adenocarcinoma, we comprehensively analyzed the data of 491 patients from The Cancer Genome Atlas. Using log-rank and Kruskal-Wallis analysis, Oncoprint, Kaplan-Meier survival plots, and a nomogram, we found that EGFR^L858R with co-mutation TP53 was significant prognostic determinant versus that with co-wild TP53 (hazard ratio, 2.77, P = 0.012). Further gene co-expression network and functional enrichment analysis indicated that co-mutation of EGFR^L858R/TP53 increases the expression of COMP and ITGB8, which are involved in extracellular matrix organization and cell surface receptor signaling pathways, thus contributing to poor prognosis in lung adenocarcinoma. Validation was performed using three GEO profiles along with colony formation and CCK-8 assays for proliferation, transwell and wound-healing for migration in transfected H1299 and A549 cell lines. To the best of our knowledge, these results are the first to indicate that patients harboring the co-mutation of EGFR^L858R/TP53 show increased expression of COMP and ITGB8, which participate in extracellular matrix dysfunction and can be used as prognostic biomarkers in patients with lung adenocarcinoma.

Expression and prognostic analyses of ITGA11, ITGB4 and ITGB8 in human non-small cell lung cancer

Background

Integrins play a crucial role in the regulation process of cell proliferation, migration, differentiation, tumor invasion and metastasis. ITGA11, ITGB4 and ITGB8 are three encoding genes of integrins family. Accumulative evidences have proved that abnormal expression of ITGA11, ITGB4 and ITGB8 are a common phenomenon in different malignances. However, their expression patterns and prognostic roles for patients with non-small cell lung cancer (NSCLC) have not been completely illustrated.

Methods

We investigated the expression patterns and prognostic values of ITGA11, ITGB4 and ITGB8 in patients with NSCLC through using a series of databases and various datasets, including ONCOMINE, GEPIA, HPA, TCGA and GEO datasets.

Results

We found that the expression levels of ITGA11 and ITGB4 were significantly upregulated in both LUAD and LUSC, while ITGB8 was obviously upregulated in LUSC. Additionally, higher expression level of ITGB4 revealed a worse OS in LUAD.

Conclusion

Our findings suggested that ITGA11 and ITGB4 might have the potential ability to act as diagnostic biomarkers for both LUAD and LUSC, while ITGB8 might serve as diagnostic biomarker for LUSC. Furthermore, ITGB4 could serve as a potential prognostic biomarker for LUAD.

Expression of polydom in dermal neurofibroma and surrounding dermis in von Recklinghausen's disease

BACKGROUND

Neurofibromas in von Recklinghausen's disease (vRD) can develop in the dermis. Therefore, we hypothesized that a dermal niche exists that promotes the development of these neurofibromas in subjects with vRD.

OBJECTIVE

The purpose of this study is to examine the function of polydom, known as a ligand for integrin, mediating cell adhesion, and expressed in mouse nerve tissue, in promotion of neurofibroma.

METHODS

Molecular, transcriptome and immunohistochemical analysis were performed to investigate the association between polydom expression and neurofibroma development.

RESULTS

Polydom mRNA levels were significantly higher in neurofibroma tissue than in control tissue. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis of RNA purified from primary cultured dermal neurofibroma cells demonstrated significantly higher polydom mRNA expression in cells derived from the surrounding dermis of neurofibromas compared to those from normal human dermal fibroblasts. RNA sequencing was used to compare gene expression between cultured cells derived from dermal neurofibroma-surrounding tissue with or without polydom knockdown. Subsequent gene ontology assays revealed that expression of integrinβ8 (ITGB8), a factor that releases transforming growth factor-β (TGF-β) from pro-TGF-β, was downregulated following polydom knockdown, suggesting upregulation of polydom-mediated TGF-β production. Furthermore, we observed a strong association between polydom expression and the increase in platelet-derived growth factor B (PDGFB) expression in primary cultured cells from the surrounding dermis of neurofibromas exposed to TGF-β1.

CONCLUSION

Our results suggest that increased polydom expression in the dermis surrounding neurofibromas may promote dermal neurofibroma development by activating the TGF-β signaling pathway.

Identification of potential diagnostic and therapeutic target genes for lung squamous cell carcinoma

The purpose of this study was to identify potential molecular markers of lung squamous cell carcinoma (LUSC). Three datasets containing LUSC mRNA sequencing data were downloaded from the Gene Expression Omnibus, The Cancer Genome Atlas and the Gene Expression Profiling Interactive Analysis databases. These datasets were used to identify significantly differentially expressed genes (DEGs) in LUSC. A protein-protein interaction network of the DEGs was constructed followed by Gene Ontology, Kyoto Encyclopedia of Genes and Genomes and overall survival analyses of the DEGs. A total of 37 DEGs between LUSC and normal tissues were identified, including 26 downregulated genes and 11 upregulated genes. Biological Process enrichment analysis revealed that the DEGs were mainly enriched in ‘cell adhesion’, ‘cell-matrix adhesion’, ‘anatomical structure morphogenesis’, ‘ECM-receptor interaction’ and ‘focal adhesion’. Overall survival analysis demonstrated that transcription factor 21, α-2-macroglobulin, acyl-CoA synthetase long chain family member 5, integrin subunit β8, meiotic nuclear divisions 1 and secretoglobin family 1A member 1 were significantly associated with the occurrence and development of lung cancer, and these genes were selected as hub genes. The results obtained in the present study may aid the elucidation of the molecular mechanisms involved in the development of LUSC and may provide potential targets for LUSC treatment.

MicroRNAs as Potential Targets for Therapeutic Intervention With Metastasis of Non-small Cell Lung Cancer

The death toll of non-small cell lung cancer (NSCLC) patients is primarily due to metastases, which are poorly amenable to therapeutic intervention. In this review we focus on miRs associated with metastasis of NSCLC as potential new targets for anti-metastatic therapy. We discuss miRs validated as therapeutic targets by in vitro data, identification of target(s) and pathway(s) and in vivo efficacy data in at least one clinically-relevant metastasis-related model. A few of the discussed miRs correlate with the clinical status of NSCLC patients. Using miRs as therapeutic agents has the advantage that targeting a single miR can potentially interfere with several metastatic pathways. Depending on their mode of action, the corresponding miRs can be up- or down-regulated compared to normal matching tissues. Here, we describe therapeutic approaches for reconstitution therapy and miR inhibition, general principles of anti-metastatic therapy as well as current technical pitfalls.

Integrin Subunit beta 8 (ITGB8) Upregulation Is an Independent Predictor of Unfavorable Survival of High-Grade Serous Ovarian Carcinoma Patients

Background

ITGB8 encodes a β subunit of integrin (integrin β8), which is upregulated in some types of cancer. In the current study, we examined the expression profile of ITGB8 in serous ovarian cancer (SOVC) and investigated its potential as an independent prognostic indicator for overall survival (OS) and recurrence-free survival (RFS) in high-grade SOVC.

Material/Methods

A secondary study was conducted based on genomic and survival data in large online databases, including the Gene Expression Omnibus (GEO), the Human Protein Atlas (HPA), and the Cancer Genome Atlas-Ovarian cancer (TCGA-OV). Kaplan-Meier curves were generated to evaluate the association between ITGB8 expression and OS/RFS. Univariate and multivariate analysis were performed with the Cox regression model.

Results

ITGB8 was significantly upregulated in ovarian cancer tissues compared to that in normal ovary tissues. High-grade SOVC patients with high ITGB8 expression had significantly shorter OS and RFS compared to their low-expression counterparts. Increased ITGB8 expression might be an independent prognostic indicator of unfavorable OS (HR: 1.424, 95%CI: 1.228–1.653, p<0.001) and RFS (HR: 2.167, 95%CI: 1.507–3.114, p<0.001) in high-grade SOVC. DNA amplification was frequent (149/509, 29.3%) in high-grade SOVC patients and was associated with increased ITGB8 expression compared to the copy-neutral cases.

Conclusions

ITGB8 expression might be a valuable prognostic biomarker in high-grade SOVC, the expression of which might be regulated by its DNA copy numbers.

Inhibiting Integrin β8 to Differentiate and Radiosensitize Glioblastoma-Initiating Cells

Glioblastomas (GB) are malignant brain tumors with poor prognosis despite treatment with surgery and radio/chemotherapy. These tumors are defined by an important cellular heterogeneity and notably contain a subpopulation of GB-initiating cells (GIC), which contribute to tumor aggressiveness, resistance, and recurrence. Some integrins are specifically expressed by GICs and could be actionable targets to improve GB treatment. Here, integrin β8 (ITGB8) was identified as a potential selective target in this highly tumorigenic GIC subpopulation. Using several patient-derived primocultures, it was demonstrated that ITGB8 is overexpressed in GICs compared with their differentiated progeny. Furthermore, ITGB8 is also overexpressed in GB, and its overexpression is correlated with poor prognosis and with the expression of several other classic stem cell markers. Moreover, inhibiting ITGB8 diminished several main GIC characteristics and features, including self-renewal ability, stemness, migration potential, and tumor formation capacity. Blockade of ITGB8 significantly impaired GIC cell viability via apoptosis induction. Finally, the combination of radiotherapy and ITGB8 targeting radiosensitized GICs through postmitotic cell death. IMPLICATIONS: This study identifies ITGB8 as a new selective marker for GICs and as a promising therapeutic target in combination with chemo/radiotherapy for the treatment of highly aggressive brain tumors.

Comprehensive bioinformation analysis of the miRNA of PLCE1 knockdown in esophageal squamous cell carcinoma

Phospholipase C epsilon 1 (PLCE1) has been recognized as a novel susceptibility marker for esophageal squamous cell carcinoma (ESCC). The purpose of our study is to investigate its effect on the regulation of miRNA expression so as to translating the data into a novel strategy in control of ESCC. In this study, PLCE1 siRNA and vector-only plasmid were stably transfected into Eca109 and EC9706 cells and then subjected to miRNA array analysis, and quantitative real-time PCR was applied to validate miRNA array data. Then bioinformatic analyses, such as GO and pathway software, were conducted to obtain data on these differentially expressed miRNAs-targeted genes (DEGs) and clarify their function and pathway. The results showed that 36 miRNAs were found to be differentially expressed in PLCE1 siRNA-transfected cells compared with the control cells. In particular, 28 miRNAs were upregulated while 8 miRNAs were downregulated. Gene Ontology analysis showed that the function of the DEGs included cell cycle arrest, cell-matrix adhesion, apoptosis, etc. After this, the major pathways associated with the DEGs were regulation of actin cytoskeleton, TGF-beta signaling pathway, Notch signaling pathway and so on. Taken together, these results showed that the knockdown of PLCE1 may play a vital role in the control of ESCC. Further investigation will reveal and verify the function and pathway of the DEGs for the development of novel treatment strategy for the better control of ESCC.

The tumour-promoting receptor tyrosine kinase, EphB4, regulates expression of integrin-β8 in prostate cancer cells

Background

The EphB4 receptor tyrosine kinase is overexpressed in many cancers including prostate cancer. The molecular mechanisms by which this ephrin receptor influences cancer progression are complex as there are tumor-promoting ligand-independent mechanisms in place as well as ligand-dependent tumor suppressive pathways.

Methods

We employed transient knockdown of EPHB4 in prostate cancer cells, coupled with gene microarray analysis, to identify genes that were regulated by EPHB4 and may represent linked tumor-promoting factors. We validated target genes using qRT-PCR and employed functional assays to determine their role in prostate cancer migration and invasion.

Results

We discovered that over 500 genes were deregulated upon EPHB4 siRNA knockdown, with integrin β8 (ITGB8) being the top hit (29-fold down-regulated compared to negative non-silencing siRNA). Gene ontology analysis found that the process of cell adhesion was highly deregulated and two other integrin genes, ITGA3 and ITGA10, were also differentially expressed. In parallel, we also discovered that over-expression of EPHB4 led to a concomitant increase in ITGB8 expression. In silico analysis of a prostate cancer progression microarray publically available in the Oncomine database showed that both EPHB4 and ITGB8 are highly expressed in prostatic intraepithelial neoplasia, the precursor to prostate cancer. Knockdown of ITGB8 in PC-3 and 22Rv1 prostate cancer cells in vitro resulted in significant reduction of cell migration and invasion.

Conclusions

These results reveal that EphB4 regulates integrin β8 expression and that integrin β8 plays a hitherto unrecognized role in the motility of prostate cancer cells and thus targeting integrin β8 may be a new treatment strategy for prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1164-6) contains supplementary material, which is available to authorized users.

Differential regulation of aggressive features in melanoma cells by members of the miR-17-92 complex

The various roles of microRNAs (miRNAs) in controlling the phenotype of cancer cells are the focus of contemporary research efforts. We have recently shown that miR-17 directly targets the ADAR1 gene and thereby enhances melanoma cell aggressiveness. miR-17 and miR-20a belong to the miR-17/92 complex, and their mature forms are identical except for two non-seed nucleotides. Nevertheless, here we show that these two miRNAs carry markedly different effects on melanoma cells. A strong positive correlation was observed between the expression of miR-17 and miR-20a among various melanoma cultures. Luciferase assays showed that miR-17 but not miR-20a directly targets the 3’ untranslated region of the ADAR1 gene. Ectopic expression of these miRNAs in melanoma cells differentially alters the expression of five exemplar TargetScan-predicted target genes: ADAR1, ITGB8, TGFBR2, MMP2 and VEGF-A. Whole-genome expression microarrays confirm a markedly differential effect on the transcriptome. Functionally, over-expression of miR-20a but not of miR-17 in melanoma cells inhibits net proliferation in vitro. The differential functional effect was observed following ectopic expression of the mature miRNA or of the pre-miRNA sequences. This suggests that the two non-seed nucleotides dictate target sequence recognition and overall functional relevance. These miRNAs are clearly not redundant in melanoma cell biology.

Protein tyrosine phosphatase-PEST and β8 integrin regulate spatiotemporal patterns of RhoGDI1 activation in migrating cells

Directional cell motility is essential for normal development and physiology, although how motile cells spatiotemporally activate signaling events remains largely unknown. Here, we have characterized an adhesion and signaling unit comprised of protein tyrosine phosphatase (PTP)-PEST and the extracellular matrix (ECM) adhesion receptor β8 integrin that plays essential roles in directional cell motility. β8 integrin and PTP-PEST form protein complexes at the leading edge of migrating cells and balance patterns of Rac1 and Cdc42 signaling by controlling the subcellular localization and phosphorylation status of Rho GDP dissociation inhibitor 1 (RhoGDI1). Translocation of Src-phosphorylated RhoGDI1 to the cell's leading edge promotes local activation of Rac1 and Cdc42, whereas dephosphorylation of RhoGDI1 by integrin-bound PTP-PEST promotes RhoGDI1 release from the membrane and sequestration of inactive Rac1/Cdc42 in the cytoplasm. Collectively, these data reveal a finely tuned regulatory mechanism for controlling signaling events at the leading edge of directionally migrating cells.

Fibroblast α11β1 integrin regulates tensional homeostasis in fibroblast/A549 carcinoma heterospheroids

We have previously shown that fibroblast expression of α11β1 integrin stimulates A549 carcinoma cell growth in a xenograft tumor model. To understand the molecular mechanisms whereby a collagen receptor on fibroblast can regulate tumor growth we have used a 3D heterospheroid system composed of A549 tumor cells and fibroblasts without (α11+/+) or with a deletion (α11-/-) in integrin α11 gene. Our data show that α11-/-/A549 spheroids are larger than α11+/+/A549 spheroids, and that A549 cell number, cell migration and cell invasion in a collagen I gel are decreased in α11-/-/A549 spheroids. Gene expression profiling of differentially expressed genes in fibroblast/A549 spheroids identified CXCL5 as one molecule down-regulated in A549 cells in the absence of α11 on the fibroblasts. Blocking CXCL5 function with the CXCR2 inhibitor SB225002 reduced cell proliferation and cell migration of A549 cells within spheroids, demonstrating that the fibroblast integrin α11β1 in a 3D heterospheroid context affects carcinoma cell growth and invasion by stimulating autocrine secretion of CXCL5. We furthermore suggest that fibroblast α11β1 in fibroblast/A549 spheroids regulates interstitial fluid pressure by compacting the collagen matrix, in turn implying a role for stromal collagen receptors in regulating tensional hemostasis in tumors. In summary, blocking stromal α11β1 integrin function might thus be a stroma-targeted therapeutic strategy to increase the efficacy of chemotherapy.

Screening of key genes in gastric cancer with DNA microarray analysis

Background

The aim of this study was to identify key genes and novel potential therapeutic targets related to gastric cancer (GC) by comparing cancer tissue samples and healthy control samples using DNA microarray analysis.

Methods

Microarray data set GSE19804 was downloaded from Gene Expression Omnibus. Preprocessing and differential analysis were conducted with of R statistical software packages, and a number of differentially expressed genes (DEGs) were obtained. Cluster analysis was also done with gene expression values. Functional enrichment analysis was performed for all the DEGs with DAVID tools. The significantly up- and downregulated genes were selected out and their interactors were retrieved with STRING and HitPredict, followed by construction of networks. For all the genes in the two networks, GeneCodis was chosen for gene function annotation.

Results

A total of 638 DEGs were identified, and we found that SPP1 and FABP4 were the markedly up- and downregulated genes, respectively. Cell cycle and regulation of proliferation were the most significantly overrepresented functional terms in up- and downregulated genes. In addition, extracellular matrix–receptor interaction was found to be significant in the SPP1-included interaction network.

Conclusions

A range of DEGs were obtained for GC. These genes not only provided insights into the pathogenesis of GC but also could develop into biomarkers for diagnosis or treatment.

αvβ8 integrin interacts with RhoGDI1 to regulate Rac1 and Cdc42 activation and drive glioblastoma cell invasion

Experiments with human cancer glioblastoma multiforme cell lines, primary patient samples, and preclinical mouse models are performed to show that αvβ8 integrin and RhoGDI1 are components of a signaling axis that drives brain tumor cell invasion via regulation of Rho GTPase activation.

The malignant brain cancer glioblastoma multiforme (GBM) displays invasive growth behaviors that are regulated by extracellular cues within the neural microenvironment. The adhesion and signaling pathways that drive GBM cell invasion remain largely uncharacterized. Here we use human GBM cell lines, primary patient samples, and preclinical mouse models to demonstrate that integrin αvβ8 is a major driver of GBM cell invasion. β8 integrin is overexpressed in many human GBM cells, with higher integrin expression correlating with increased invasion and diminished patient survival. Silencing β8 integrin in human GBM cells leads to impaired tumor cell invasion due to hyperactivation of the Rho GTPases Rac1 and Cdc42. β8 integrin coimmunoprecipitates with Rho-GDP dissociation inhibitor 1 (RhoGDI1), an intracellular signaling effector that sequesters Rho GTPases in their inactive GDP-bound states. Silencing RhoGDI1 expression or uncoupling αvβ8 integrin–RhoGDI1 protein interactions blocks GBM cell invasion due to Rho GTPase hyperactivation. These data reveal for the first time that αvβ8 integrin, via interactions with RhoGDI1, regulates activation of Rho proteins to promote GBM cell invasiveness. Hence targeting the αvβ8 integrin–RhoGDI1 signaling axis might be an effective strategy for blocking GBM cell invasion.