Downregulation of laminin alpha4 chain expression inhibits glioma invasion in vitro and in vivo

Glioblastoma-derived migrasomes promote migration and invasion by releasing PAK4 and LAMA4

Almost all high-grade gliomas, particularly glioblastoma (GBM), are highly migratory and aggressive. Migrasomes are organelles produced by highly migratory cells capable of mediating intercellular communication. Thus, GBM cells may produce migrasomes during migration. However, it remains unclear whether migrasomes can influence GBM migration and invasion. In this study, we observed the presence and formation of migrasomes in GBM cells. We found that expression levels of key migrasome formation factor, tetraspanin 4 (TSPAN4), correlated positively with pathological grade and poor prognosis of GBM based on the databases and clinical samples analysis. Subsequently, we knocked down TSPAN4 and found that GBM cell migration and invasion were significantly inhibited due to the reduced formation of migrasomes. We further confirmed that migrasomes are enriched in extracellular matrix (ECM)-related proteins such as p21-activating kinase 4 (PAK4) and laminin alpha 4 (LAMA4). Our experimental results suggest that migrasomes promote GBM cells migration by releasing such proteins into the extracellular space. Overall, we identified migrasomes in GBM and the molecular mechanisms by which they regulate them, providing potential targets for treating GBM.

New Anti-Angiogenic Therapy for Glioblastoma With the Anti-Depressant Sertraline

BACKGROUND AND AIMS

Anti-angiogenic therapies prolong patient survival in some malignancies but not glioblastoma. We focused on the relationship between the differentiation of glioma stem like cells (GSCs) into tumor derived endothelial cells (TDECs) and, anti-angiogenic therapy resistance. Especially we aimed to elucidate the mechanisms of drug resistance of TDECs to anti-angiogenic inhibitors and identify novel anti-angiogenic drugs with clinical applications.

RESULTS

The mouse GSCs, 005, were differentiated into TDECs under hypoxic conditions, and TDECs had endothelial cell characteristics independent of the vascular endothelial growth factor (VEGF) pathway. In vivo, inhibition of the VEGF pathway had no anti-tumor effect and increased the percentage of TDECs in the 005 mouse model. Novel anti-angiogenic drugs for glioblastoma were evaluated using a tube formation assay and a drug repositioning strategy with existing blood-brain barrier permeable drugs. Drug screening revealed that the antidepressant sertraline inhibited tube formation of TDECs. Sertraline was administered to differentiated TDECs in vitro and 005 mouse models in vivo to evaluate genetic changes by RNA-Seq and tumor regression effects by immunohistochemistry and MRI. Sertraline reduced Lama4 and Ang2 expressions of TDEC, which play an important role in non-VEGF-mediated angiogenesis in tumors. The combination of a VEGF receptor inhibitor axitinib, and sertraline improved survival and reduced tumor growth in the 005 mouse model.

CONCLUSION

Collectively, our findings showed the diversity of tumor vascular endothelial cells across VEGF and non-VEGF pathways led to anti-angiogenic resistance. The combination of axitinib and sertraline can represent an effective anti-angiogenic therapy for glioblastoma with safe, low cost, and fast availability.

Antisense Oligonucleotides for Rapid Translation of Gene Therapy in Glioblastoma

PURPOSE

The limited efficacy of current treatments for malignant brain tumors necessitates novel therapeutic strategies. This study aimed to assess the potential of antisense oligonucleotides (ASOs) as adjuvant therapy for high-grade gliomas, focusing on their CNS penetration and clinical translation prospects.

METHODS

A comprehensive review of the existing literature was conducted to evaluate the implications of ASOs in neuro-oncology. Studies that investigated ASO therapy's efficacy, CNS penetration, and safety profile were analyzed to assess its potential as a therapeutic intervention for high-grade gliomas.

RESULTS

ASOs present a promising avenue for enhancing targeted gene therapies in malignant gliomas. Their potent CNS penetration, in vivo durability, and efficient transduction offer advantages over conventional treatments. Preliminary in vivo and in vitro studies suggest ASOs as a viable adjuvant therapy for high-grade gliomas, warranting further exploration in clinical trials.

CONCLUSIONS

ASOs hold significant promise as adjuvant therapy for high-grade gliomas, offering improved CNS penetration and durability compared with existing treatments. While preliminary studies are encouraging, additional research is needed to establish the safety and efficacy of ASO therapy in clinical settings. Further investigation and clinical trials are warranted to validate ASOs as a transformative approach in neuro-oncology.

HIF-1α-mediated LAMC1 overexpression is an unfavorable predictor of prognosis for glioma patients: evidence from pan-cancer analysis and validation experiments

BACKGROUND

Laminin subunit gamma-1 (LAMC1) is a major extracellular matrix molecule involved in the tumor microenvironment. Knowledge of the biological features and clinical relevance of LAMC1 in cancers remains limited.

METHODS

We conducted comprehensive bioinformatics analysis of LAMC1 gene expression and clinical relevance in pan-cancer datasets of public databases and validated LAMC1 expression in glioma tissues and cell lines. The association and regulatory mechanism between hypoxia inducible factor-1α (HIF-1α) and LAMC1 expression were explored.

RESULTS

LAMC1 expression in most cancers in The Cancer Genome Atlas (TCGA) including glioma was significantly higher than that in normal tissues, which had a poor prognosis and were related to various clinicopathological features. Data from the Chinese Glioma Genome Atlas also showed high expression of LAMC1 in glioma associated with poor prognoses. In clinical glioma tissues, LAMC1 protein was highly expressed and correlated to poor overall survival. LAMC1 knockdown in Hs683 glioma cells attenuated cell proliferation, migration, and invasion, while overexpression of LAMC1 in U251 cells leads to the opposite trend. Most TCGA solid cancers including glioma showed enhancement of HIF-1α expression. High HIF-1α expression leads to adverse prognosis in gliomas, besides, HIF-1α expression was positively related to LAMC1. Mechanistically, HIF-1α directly upregulated LAMC1 promotor activity. Hypoxia (2% O2)-treated Hs683 and U251 cells exhibited upregulated HIF-1α and LAMC1 expression, which was significantly attenuated by HIF-1α inhibitor YC-1 and accompanied by attenuated cell proliferation and invasion.

CONCLUSIONS

High expression of LAMC1 in some solid tumors including gliomas suggests a poor prognosis. The hypoxic microenvironment in gliomas activates the HIF-1α/LAMC1 signaling, thereby promoting tumor progression. Targeted intervention on the HIF-1α/LAMC1 signaling attenuates cell growth and invasion, suggesting a new strategy for glioma treatment.

Effect of LAMA4 on Prognosis and Its Correlation with Immune Infiltration in Gastric Cancer

Background

Laminin alpha 4 (LAMA4) is widely distributed in the basement membranes of various tissues. It can regulate cancer cell proliferation and migration. We investigated the effects of LAMA4 in gastric cancer (GC).

Methods

LAMA4 expression patterns were analyzed in GC using the Gene Expression Omnibus (GEO), Gene Expression Profiling Interactive Analysis (GEPIA), and UALCAN. Correlations between LAMA4 expression and clinicopathological characteristics were evaluated using data from The Cancer Genome Atlas (TCGA). The survival analysis was examined using the Kaplan-Meier plotter and GEPIA and ascertained by multivariate Cox analysis. Genetic alterations and DNA methylation of LAMA4 were analyzed using cBioPortal and MethSurv. LinkedOmics was applied to identify coexpressed genes of LAMA4. The association between LAMA4 and infiltration of immune cells was explored using Tumor Immune Estimation Resource (TIMER) and GEPIA.

Results

LAMA4 was highly expressed in GC, and its upregulation significantly correlated with T classification (P = 0.040). LAMA4 expression was an independent risk factor for overall survival (OS, P = 0.033). Patients with genetic alterations of LAMA4 showed a significantly better disease-free survival (DFS, P = 0.022). Ten CpG sites of LAMA4 were significantly associated with prognosis in GC. The functions of LAMA4 and coexpression genes were mainly involved in extracellular matrix (ECM) receptor interaction. LAMA4 expression significantly correlated with infiltration of macrophages (P < 0.001), CD4+ T cells (P < 0.001), and dendritic cells (P < 0.001). Furthermore, LAMA4 expression was significantly associated with markers of M2 and tumor-associated macrophages (TAMs).

Conclusion

LAMA4 expression was linked to GC prognosis and immune cell infiltration, indicating its potential use as a prognostic biomarker and therapeutic target.

Laminin Subunit Alpha-4 and Osteopontin Are Glioblastoma-Selective Secreted Proteins That Are Increased in the Cerebrospinal Fluid of Glioblastoma Patients

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. The purpose of the present study was to identify GBM cell-selective secreted proteins by analyzing conditioned media (CM) from GBM, breast, and colon cancer cell lines using sequential window acquisition of all theoretical spectra-mass spectrometry (SWATH-MS) and targeted proteomics. We identified 2371 proteins in the CM from GBM and the other cancer cell lines. Among the proteins identified, 15 showed significantly higher expression in the CM from GBM cell lines than in those from other cancer cell lines. These GBM-selective secreted proteins were further quantified in the cerebrospinal fluid (CSF) from patients with GBM. Laminin subunit alpha-4 (LAMA4) and osteopontin (OPN) had increased expression levels in the CSF from GBM patients compared to those from non-brain tumor patients. In addition, the areas under the curves in a receiver operating characteristic analysis of LAMA4 and OPN were greater than 0.9, allowing for discrimination of GBM patients from non-brain tumor patients. The CSF levels of LAMA4 and OPN were also significantly correlated with the GBM tumor volume. These results suggest that LAMA4 and OPN are secreted from GBM cells into the CSF and appear to be candidates as diagnostic markers and therapeutic targets for GBM.

The genomic landscape of Epstein-Barr virus-associated pulmonary lymphoepithelioma-like carcinoma

Pulmonary lymphoepithelioma-like carcinoma (LELC) is a rare and distinct subtype of primary lung cancer characterized by Epstein-Barr virus (EBV) infection. Herein, we reported the mutational landscape of pulmonary LELC using whole-exome sequencing, targeted deep sequencing and single-nucleotide polymorphism arrays. We identify a low degree of somatic mutation but widespread existence of copy number variations. We reveal predominant signature 2 mutations and frequent loss of type I interferon genes that are involved in the host-virus counteraction. Integrated analysis shows enrichment of genetic lesions affecting several critical pathways, including NF-κB, JAK/STAT, and cell cycle. Notably, multi-dimensional comparison unveils that pulmonary LELC resemble NPC but are clearly different from other lung cancers, natural killer/T-cell lymphoma or EBV-related gastric cancer in terms of genetic features. In all, our study illustrates a distinct genomic landscape of pulmonary LELC and provides a road map to facilitate genome-guided personalized treatment.

The rare lung cancer subtype pulmonary lymphoepithelioma-like carcinoma is linked to Epstein-Barr virus infection. Here, the authors provide a mutational landscape for this cancer, showing a low burden of somatic mutations and high prevalence of copy number variations.

Blockade of a Laminin-411-Notch Axis with CRISPR/Cas9 or a Nanobioconjugate Inhibits Glioblastoma Growth through Tumor-Microenvironment Cross-talk

There is an unmet need for the treatment of glioblastoma multiforme (GBM). The extracellular matrix, including laminins, in the tumor microenvironment is important for tumor invasion and progression. In a panel of 226 patient brain glioma samples, we found a clinical correlation between the expression of tumor vascular laminin-411 (α4β1γ1) with higher tumor grade and with expression of cancer stem cell (CSC) markers, including Notch pathway members, CD133, Nestin, and c-Myc. Laminin-411 overexpression also correlated with higher recurrence rate and shorter survival of GBM patients. We also showed that depletion of laminin-411 α4 and β1 chains with CRISPR/Cas9 in human GBM cells led to reduced growth of resultant intracranial tumors in mice and significantly increased survival of host animals compared with mice with untreated cells. Inhibition of laminin-411 suppressed Notch pathway in normal and malignant human brain cell types. A nanobioconjugate potentially suitable for clinical use and capable of crossing blood-brain barrier was designed to block laminin-411 expression. Nanobioconjugate treatment of mice carrying intracranial GBM significantly increased animal survival and inhibited multiple CSC markers, including the Notch axis. This study describes an efficient strategy for GBM treatment via targeting a critical component of the tumor microenvironment largely independent of heterogeneous genetic mutations in glioblastoma.Significance: Laminin-411 expression in the glioma microenvironment correlates with Notch and other cancer stem cell markers and can be targeted by a novel, clinically translatable nanobioconjugate to inhibit glioma growth.

Chemo brain or tumor brain - that is the question: the presence of extracranial tumors profoundly affects molecular processes in the prefrontal cortex of TumorGraft mice

Cancer chemotherapy causes numerous persistent central nervous system complications. This condition is known as chemo brain. Cognitive impairments occur even before treatment, and hence are referred to as cancer associated cognitive changes, or tumor brain. There is much yet to be learned about the mechanisms of both chemo brain and tumor brain. The frequency and timing of chemo brain and tumor brain occurrence and persistence strongly suggest they may be epigenetic in nature and associated with altered gene expression. Here we used TumorGraft^TM models wherein part of a patient's tumor is removed and grafted into immune-deficient mice and conducted global gene expression and DNA methylation analysis. We show that malignant non-central nervous system tumor growth causes profound molecular alterations in the brain. Mice harbouring triple negative or progesterone positive breast cancer TumorGrafts exhibited altered gene expression, decreased levels of DNA methylation, increased levels of DNA hydroxymethylation, and oxidative stress in the prefrontal cortex. Interestingly, chemotherapy did not have any additional synergistic effects on the analyzed processes. The molecular changes observed in this study are known signs of neurodegeneration and brain aging. This study provides an important roadmap for future large-scale analysis of the molecular and cellular mechanisms of tumor brain.

Cumulative prognostic power of laminin genes in colorectal cancer

Background

Laminins are a major family of extracellular matrix proteins and the main component of basement membranes. Laminins are involved in many if not all stages of cancer progression, and expression of laminin genes has prognostic value in various types of cancer, including colorectal. Only single laminin genes or components of a single laminin trimer with significant differential expression have been regarded as potential biomarkers to date.

Results

Here we compared prognostic power of classifiers constructed from sets of laminin genes with that of any single laminin gene. The analysis showed that cumulative prognostic power of sets of laminin genes was higher and was achieved already with pairs and triples of the genes. Interestingly, components of the pairs and the triples did not belong to any known laminin trimer, but, taken together with the gene weights, suggested higher LAMA4/LAMA5 expression ratio in patients with poor prognosis.

Conclusions

Analysis of the laminin expression profile rather than expression of the single genes or components of laminin trimers is useful for colorectal cancer prognosis in patients. High LAMA4/LAMA5 ratio is associated with increased permeability of basement membranes suggesting that basement membranes produced by colorectal tumors might be an important hindrance to their own dissemination in patients.

Human SLFN5 is a transcriptional co-repressor of STAT1-mediated interferon responses and promotes the malignant phenotype in glioblastoma

We provide evidence that the IFN-regulated member of the Schlafen (SLFN) family of proteins, SLFN5, promotes the malignant phenotype in glioblastoma multiforme (GBM). Our studies indicate that SLFN5 expression promotes motility and invasiveness of GBM cells, and that high levels of SLFN5 expression correlate with high grade gliomas and shorter overall survival in patients suffering from GBM. In efforts to uncover the mechanism by which SLFN5 promotes GBM tumorigenesis, we found that this protein is a transcriptional co-repressor of STAT1. Type-I IFN treatment triggers the interaction of STAT1 with SLFN5, and the resulting complex negatively controls STAT1-mediated gene transcription via interferon stimulated response elements (ISRE). Thus, SLFN5 is both an IFN-stimulated response gene and a repressor of IFN-gene transcription, suggesting the existence of a negative-feedback regulatory loop that may account for suppression of antitumor immune responses in glioblastoma.

Comprehensive proteome profiling of glioblastoma-derived extracellular vesicles identifies markers for more aggressive disease

Extracellular vesicles (EVs) play key roles in glioblastoma (GBM) biology and represent novel sources of biomarkers that are detectable in the peripheral circulation. Despite this notionally non-invasive approach to assess GBM tumours in situ, a comprehensive GBM EV protein signature has not been described. Here, EVs secreted by six GBM cell lines were isolated and analysed by quantitative high-resolution mass spectrometry. Overall, 844 proteins were identified in the GBM EV proteome, of which 145 proteins were common to EVs secreted by all cell lines examined; included in the curated EV compendium (Vesiclepedia_559; http://microvesicles.org). Levels of 14 EV proteins significantly correlated with cell invasion (invadopodia production; r² > 0.5, p < 0.05), including several proteins that interact with molecules responsible for regulating invadopodia formation. Invadopodia, actin-rich membrane protrusions with proteolytic activity, are associated with more aggressive disease and are sites of EV release. Gene levels corresponding to invasion-related EV proteins showed that five genes (annexin A1, actin-related protein 3, integrin-β1, insulin-like growth factor 2 receptor and programmed cell death 6-interacting protein) were significantly higher in GBM tumours compared to normal brain in silico, with common functions relating to actin polymerisation and endosomal sorting. We also show that Cavitron Ultrasonic Surgical Aspirator (CUSA) washings are a novel source of brain tumour-derived EVs, demonstrated by particle tracking analysis, TEM and proteome profiling. Quantitative proteomics corroborated the high levels of proposed invasion-related proteins in EVs enriched from a GBM compared to low-grade astrocytoma tumour. Large-scale clinical follow-up of putative biomarkers, particularly the proposed survival marker annexin A1, is warranted.

FBW7 suppression leads to SOX9 stabilization and increased malignancy in medulloblastoma

SOX9 is a master transcription factor that regulates development and stem cell programs. However, its potential oncogenic activity and regulatory mechanisms that control SOX9 protein stability are poorly understood. Here, we show that SOX9 is a substrate of FBW7, a tumor suppressor, and a SCF (SKP1/CUL1/F‐box)‐type ubiquitin ligase. FBW7 recognizes a conserved degron surrounding threonine 236 (T236) in SOX9 that is phosphorylated by GSK3 kinase and consequently degraded by SCF^FBW7α. Failure to degrade SOX9 promotes migration, metastasis, and treatment resistance in medulloblastoma, one of the most common childhood brain tumors. FBW7 is either mutated or downregulated in medulloblastoma, and in cases where FBW7 mRNA levels are low, SOX9 protein is significantly elevated and this phenotype is associated with metastasis at diagnosis and poor patient outcome. Transcriptional profiling of medulloblastoma cells expressing a degradation‐resistant SOX9 mutant reveals activation of pro‐metastatic genes and genes linked to cisplatin resistance. Finally, we show that pharmacological inhibition of PI3K/AKT/mTOR pathway activity destabilizes SOX9 in a GSK3/FBW7‐dependent manner, rendering medulloblastoma cells sensitive to cytostatic treatment.

Overcoming a species-specificity barrier in development of an inhibitory antibody targeting a modulator of tumor stroma

The secreted disulfide catalyst Quiescin sulfhydryl oxidase-1 (QSOX1) affects extracellular matrix organization and is overexpressed in various adenocarcinomas and associated stroma. Inhibition of extracellular human QSOX1 by a monoclonal antibody decreased tumor cell migration in a cell co-culture model and hence may have therapeutic potential. However, the species specificity of the QSOX1 monoclonal antibody has been a setback in assessing its utility as an anti-metastatic agent in vivo, a common problem in the antibody therapy industry. We therefore used structurally guided engineering to expand the antibody species specificity, improving its affinity toward mouse QSOX1 by at least four orders of magnitude. A crystal structure of the re-engineered variant, complexed with its mouse antigen, revealed that the antibody accomplishes dual-species targeting through altered contacts between its heavy and light chains, plus replacement of bulky aromatics by flexible side chains and versatile water-bridged polar interactions. In parallel, we produced a surrogate antibody targeting mouse QSOX1 that exhibits a new QSOX1 inhibition mode. This set of three QSOX1 inhibitory antibodies is compatible with various mouse models for pre-clinical trials and biotechnological applications. In this study we provide insights into structural blocks to cross-reactivity and set up guideposts for successful antibody design and re-engineering.

Effect of Laminin-A4 inhibition on cluster formation of human osteoarthritic chondrocytes

Formation of chondrocyte clusters is not only a morphological sign of osteoarthritis but it is also observed in cell culture. Active locomotion of chondrocytes is controlled by integrins in vitro. Integrins bind to Laminin-A4 (LAMA4), a protein that is highly expressed in vivo in clusters of hypertrophic chondrocytes. We tested if LAMA4 is relevant for cluster formation. Human chondrocytes were cultured in a 2D matrigel model and treated with different concentrations of a monoclonal inhibitory anti-LAMA4-antibody. Migration and cluster formation was analysed using live cell imaging technique. Full genome gene expression analysis was performed to assess the effect of LAMA4 inhibition. The data set were screened for genes relevant to cell motility. F-actin staining was performed to document cytoskeletal changes. Anti-LAMA4 treatment significantly reduced the rate of cluster formation in human chondrocytes. Cells changed their surface morphology and exhibited fewer protrusions. Expression of genes associated with cellular motility and migration was affected by anti-LAMA4 treatment. LAMA4-integrin signalling affects chondrocyte morphology and gene expression in vitro, thereby contributing to cluster formation in human osteoarthritic chondrocytes.

Laminins 411 and 421 differentially promote tumor cell migration via α6β1 integrin and MCAM (CD146)

α4-laminins, such as laminins 411 and 421, are mesenchymal laminins expressed by blood and lymphatic vessels and some tumor cells. Laminin-411 promotes migration of leukocytes and endothelial cells, but the effect of this laminin and laminin-421 on tumor cells is poorly understood. In the present study, we demonstrate that laminin-411 and, to a greater extent, laminin-421 significantly promote migration of tumor cells originated from melanomas, gliomas and different carcinomas via α6β1 integrin. In solid-phase binding assays, both laminins similarly bound α6β1 integrin but only laminin-421, among several laminin isoforms, readily bound MCAM (CD146), a cell-surface adhesion molecule strongly associated with tumor progression. Accordingly, a function-blocking mAb to MCAM inhibited tumor cell migration on laminin-421 but not on laminins 411 or 521. In tumor tissues, melanoma cells co-expressed MCAM, laminin α4, β1, β2 and γ1 chains, and integrin α6 and β1 chains. The present data highlight the novel role of α4-laminins in tumor cell migration and identify laminin-421 as a primary ligand for MCAM and a putative mediator of tumor invasion and metastasis.

An inhibitory antibody blocks the first step in the dithiol/disulfide relay mechanism of the enzyme QSOX1

Quiescin sulfhydryl oxidase 1 (QSOX1) is a catalyst of disulfide bond formation that undergoes regulated secretion from fibroblasts and is over-produced in adenocarcinomas and other cancers. We have recently shown that QSOX1 is required for incorporation of particular laminin isoforms into the extracellular matrix (ECM) of cultured fibroblasts and, as a consequence, for tumor cell adhesion to and penetration of the ECM. The known role of laminins in integrin-mediated cell survival and motility suggests that controlling QSOX1 activity may provide a novel means of combating metastatic disease. With this motivation, we developed a monoclonal antibody that inhibits the activity of human QSOX1. Here, we present the biochemical and structural characterization of this antibody and demonstrate that it is a tight-binding inhibitor that blocks one of the redox-active sites in the enzyme, but not the site at which de novo disulfides are generated catalytically. Sulfhydryl oxidase activity is thus prevented without direct binding of the sulfhydryl oxidase domain, confirming the model for the interdomain QSOX1 electron transfer mechanism originally surmised based on mutagenesis and protein dissection. In addition, we developed a single-chain variant of the antibody and show that it is a potent QSOX1 inhibitor. The QSOX1 inhibitory antibody will be a valuable tool in studying the role of ECM composition and architecture in cell migration, and the recombinant version may be further developed for potential therapeutic applications based on manipulation of the tumor microenvironment.

Gadd45a inhibits cell migration and invasion by altering the global RNA expression

Gadd45a, the first well-defined p53 downstream gene, can be induced by multiple DNA-damaging agents, which plays important roles in the control of cell cycle checkpoint, DNA repair process and signaling transduction. Our previous findings suggested that Gadd45a maintains cell-cell adhesion and cell contact inhibition. However, little is known about how Gadd45a participates in the suppression of malignancy in human cancer cells. To examine the functions of Gadd45a in cell invasion and metastasis, we performed the adhesion, wound-healing and transwell assays in Gadd45a (+/+) and Gadd45a (-/-) MEF cell lines. We found the adhesion, migration and invasive abilities were much higher in Gadd45a deficient cells. We furthermore applied high-throughput cDNA microarray analysis and bioinformatics analysis to analyze the mechanisms of Gadd45a gene in invasion and metastasis. Compared with the Gadd45a wild type cells, the Gadd45a deficient cells showed a wide range of transcripts alterations. The altered gene pathways were predicted by the MAS software, which indicated focal adhesion,cell communication,ECM-receptor interaction as the three main pathways. Real-time PCR was employed to validate the differentially expressed genes. Interestingly, we figured out that the deregulations of these genes are caused neither by genomic aberrations nor methylation status. These findings provided a novel insight that Gadd45a may involve in tumor progression by regulating related genes expressions.

Molecular profiling of pancreatic neuroendocrine tumors in sporadic and Von Hippel-Lindau patients

PURPOSE

Von Hippel-Lindau (VHL) disease is an inherited syndrome caused by germline mutations in the VHL tumor suppressor gene, predisposing to a variety of neoplasms including pancreatic neuroendocrine tumors (PanNET). In VHL disease, PanNET probably progress according to a specific pathway of carcinogenesis. Our aim was to characterize by molecular quantitative analysis a panel of molecules implicated in the VHL pathway and in tumor progression in the PanNET of patients with VHL.

EXPERIMENTAL DESIGN

The expression of 52 genes was studied by quantitative reverse transcriptase PCR in 18 patients with VHL operated on for PanNET and compared with 16 non-VHL PanNET. The VHL and non-VHL tumors were matched according to their size and cell proliferation. For some genes, we looked for differences in the protein expression in VHL PanNET (n = 31), microadenomas (n = 22), and non-VHL PanNET (n = 16), included in tissue microarray blocks.

RESULTS

Nineteen (36%) genes were significantly upregulated and three (6%) downregulated in VHL PanNET. The upregulated genes were related to (i) hypoxia-inducible factor (HIF) molecules (CA9, HIF2A, and GLUT1), (ii) angiogenesis (CDH5, VEGFR1, EDNRA, ANGPT2, CD34, VEGFR2, VEGFA, and ANGPT1), (iii) the processes of epithelial-mesenchymal transition (VIM) and/or metastasis (LAMA4 and CXCR4), (iv) growth factors and receptors (PDGFB, IRS1, and ERBB1), or (v) cell cycle (CCND1 and CDKN2A). The downregulated genes were related to (i) EMT (OCLN) and (ii) signaling pathways (RPS6KB1 and GADD45B).

CONCLUSION

This study shows that the progression of PanNET in patients with VHL tumors follows a specific pathway and supports that targeting molecules specifically involved may be of therapeutic importance.

Abrogation of PIK3CA or PIK3R1 reduces proliferation, migration, and invasion in glioblastoma multiforme cells

Glioblastoma multiforme (GBM) is a highly invasive and deadly brain tumor. Tumor cell invasion makes complete surgical resection impossible and reduces the efficacy of other therapies. Genome-wide analyses of mutations, copy-number changes, and expression patterns have provided new insights into genetic abnormalities common in GBM. We analyzed published data and identified the invasion and motility pathways most frequently altered in GBM. These were most notably the focal adhesion and integrin signaling, and extracellular matrix interactions pathways. We mapped alterations in each of these pathways and found that they included the catalytic PIK3CA and regulatory PIK3R1 subunit genes of the class IA PI3K. Knockdown of either of these genes separately in GBM cell lines by lentiviral-mediated shRNA expression resulted in decreased proliferation, migration, and invasion in all lines tested. FAK activity was reduced by knockdown of either PIK3CA or PIK3R1, and MMP2 levels were reduced by knockdown of PIK3R1. We conclude that PIK3R1, like PIK3CA, is a potential therapeutic target in GBM and that it also influences tumor cell growth and motility.

TWIST1 promotes invasion through mesenchymal change in human glioblastoma

Background

Tumor cell invasion into adjacent normal brain is a mesenchymal feature of GBM and a major factor contributing to their dismal outcomes. Therefore, better understandings of mechanisms that promote mesenchymal change in GBM are of great clinical importance to address invasion. We previously showed that the bHLH transcription factor TWIST1 which orchestrates carcinoma metastasis through an epithelial mesenchymal transition (EMT) is upregulated in GBM and promotes invasion of the SF767 GBM cell line in vitro.

Results

To further define TWIST1 functions in GBM we tested the impact of TWIST1 over-expression on invasion in vivo and its impact on gene expression. We found that TWIST1 significantly increased SNB19 and T98G cell line invasion in orthotopic xenotransplants and increased expression of genes in functional categories associated with adhesion, extracellular matrix proteins, cell motility and locomotion, cell migration and actin cytoskeleton organization. Consistent with this TWIST1 reduced cell aggregation, promoted actin cytoskeletal re-organization and enhanced migration and adhesion to fibronectin substrates. Individual genes upregulated by TWIST1 known to promote EMT and/or GBM invasion included SNAI2, MMP2, HGF, FAP and FN1. Distinct from carcinoma EMT, TWIST1 did not generate an E- to N-cadherin "switch" in GBM cell lines. The clinical relevance of putative TWIST target genes SNAI2 and fibroblast activation protein alpha (FAP) identified in vitro was confirmed by their highly correlated expression with TWIST1 in 39 human tumors. The potential therapeutic importance of inhibiting TWIST1 was also shown through a decrease in cell invasion in vitro and growth of GBM stem cells.

Conclusions

Together these studies demonstrated that TWIST1 enhances GBM invasion in concert with mesenchymal change not involving the canonical cadherin switch of carcinoma EMT. Given the recent recognition that mesenchymal change in GBMs is associated with increased malignancy, these findings support the potential therapeutic importance of strategies to subvert TWIST1-mediated mesenchymal change.

Laminin isoforms and their integrin receptors in glioma cell migration and invasiveness: Evidence for a role of alpha5-laminin(s) and alpha3beta1 integrin

Glioma cell infiltration of brain tissue often occurs along the basement membrane (BM) of blood vessels. In the present study we have investigated the role of laminins, major structural components of BMs and strong promoters of cell migration. Immunohistochemical studies of glioma tumor tissue demonstrated expression of alpha2-, alpha3-, alpha4- and alpha5-, but not alpha1-, laminins by the tumor vasculature. In functional assays, alpha3 (Lm-332/laminin-5)- and alpha5 (Lm-511/laminin-10)-laminins strongly promoted migration of all glioma cell lines tested. alpha1-Laminin (Lm-111/laminin-1) displayed lower activity, whereas alpha2 (Lm-211/laminin-2)- and alpha4 (Lm-411/laminin-8)-laminins were practically inactive. Global integrin phenotyping identified alpha3beta1 as the most abundant integrin in all the glioma cell lines, and this laminin-binding integrin exclusively or largely mediate the cell migration. Moreover, pretreatment of U251 glioma cells with blocking antibodies to alpha3beta1 integrin followed by intracerebral injection into nude mice inhibited invasion of the tumor cells into the brain tissue. The cell lines secreted Lm-211, Lm-411 and Lm-511, at different ratios. The results indicate that glioma cells secrete alpha2-, alpha4- and alpha5-laminins and that alpha3- and alpha5-laminins, found in brain vasculature, selectively promote glioma cell migration. They identify alpha3beta1 as the predominant integrin and laminin receptor in glioma cells, and as a brain invasion-mediating integrin.

Alpha4 chain laminins are widely expressed in renal cell carcinomas and have a de-adhesive function

Laminin (Lm) alpha4 chain, a constituent of Lm-411 and Lm-421, is mainly localized to mesenchyme-derived tissues, and is suggested to have a role in formation and function of endothelium, transmigration of inflammatory cells through endothelium, and invasion of certain tumors. In this study, we evaluated the distribution of alpha4 chain Lms in 33 conventional (clear cell) renal cell carcinomas (RCCs) (31 primary tumors, two metastases), two papillary RCCs, and two oncocytomas by immunohistochemistry. In all tumors, immunoreactivity for Lm alpha4 chain was found in vasculature and stroma. Basement membranes were detected around tumor cell islets in 34/37 tumors. They showed immunoreactivity for Lm alpha4 chain in 28/34 cases. Northern blotting, inhibition of protein secretion with monensin, and immunoprecipitation combined with Western blotting showed that Caki-2, ACHN, and Caki-1 renal carcinoma cell lines produce alpha4 chain Lms. In cell adhesion assay, recombinant human Lm-411 did not promote adhesion of renal carcinoma cells but inhibited adhesion to fibronectin (Fn). In cell migration assay, the cells migrated more on Lm-411 than on Fn. The results suggest that alpha4 chain Lms have a de-adhesive function and could thus play a role in detachment, migration and invasion of renal carcinoma cells in vivo.

Laminin isoforms in development and disease

The members of the laminin family of heterotrimers are major constituents of all basement membranes, sheet-like extracellular structures, present in almost all organs. The laminins bind to cell surface receptors and thereby tightly connect the basement membrane to the adjacent cell layer. This provides for the specific basement membrane functions to stabilize cellular structures, to serve as effective physical barriers, and furthermore, to govern cell fate by inducing intracellular signalling cascades. Many different types of diseases involve basement membranes and laminins. Metastasizing solid tumors must pass through basement membranes to reach the vascular system, and various microbes and viruses enter the cells through direct interaction with laminins. Furthermore, whereas mutations in one specific laminin chain lead to a muscular disorder, mutations of other laminin chains cause skin blistering and kidney defects, respectively. This review summarizes recent progress concerning the molecular mechanisms of laminins in development and disease. The current knowledge may lead to clinical treatment of lamininopathies and may include stem-cell approaches as well as gene therapy.

Identification of an active site on the laminin α4 chain globular domain that binds to αvβ3 integrin and promotes angiogenesis

Angiogenesis is important for wound healing, tumor growth, and metastasis. The laminin alpha4 chain, a component of laminin-8 and -9, is expressed in endothelial cell basement membranes. It mediates endothelial cell adhesion by binding with its receptors such as alphavbeta3 integrin and participates in new blood vessel formation. In this study, we found the recombinant laminin alpha4LG modules (rLG1-3, rLG1, and rLG2) mediate HUVECs adhesion. The attachment of HUVECs to the rLG2 was specifically inhibited by a function-blocking monoclonal antibody LM609 specific for alphavbeta3 integrin. Using deletion mutants of the alpha4LG2 revealed the HUVECs-adhesion site is located in amino acids 1121-1139. A synthetic G(1121-1139) peptide could be attached by HUVECs at same efficiency with the rLG2 and promoted angiogenesis in CAM. In conclusion, we have identified a new alphavbeta3 integrin-interacting peptide within laminin alpha4 G domain. This suggests that G(1121-1139) peptide-containing proteins may perform their biological functions by interacting with alphavbeta3 integrin.