SEMA3A

Gene Summary

Gene:SEMA3A; semaphorin 3A
Aliases: HH16, SemD, COLL1, SEMA1, SEMAD, SEMAL, coll-1, Hsema-I, SEMAIII, Hsema-III
Location:7q21.11
Summary:This gene is a member of the semaphorin family and encodes a protein with an Ig-like C2-type (immunoglobulin-like) domain, a PSI domain and a Sema domain. This secreted protein can function as either a chemorepulsive agent, inhibiting axonal outgrowth, or as a chemoattractive agent, stimulating the growth of apical dendrites. In both cases, the protein is vital for normal neuronal pattern development. Increased expression of this protein is associated with schizophrenia and is seen in a variety of human tumor cell lines. Also, aberrant release of this protein is associated with the progression of Alzheimer's disease. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:semaphorin-3A
Source:NCBIAccessed: 15 March, 2017

Ontology:

What does this gene/protein do?
Show (18)
Pathways:What pathways are this gene/protein implicaed in?
Show (1)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 15 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Cell Surface Receptors
  • Endothelial Cells
  • rap1 GTP-Binding Proteins
  • Chromosome 3
  • Tumor Suppressor Gene
  • Childhood Cancer
  • Chromosome 7
  • Breast Cancer
  • Amino Acid Sequence
  • Lung Cancer
  • Cell Proliferation
  • Neoplasm Metastasis
  • Immunohistochemistry
  • Cell Movement
  • Staging
  • Semaphorins
  • Transfection
  • Nerve Tissue Proteins
  • siRNA
  • RTPCR
  • CDC42
  • Phosphorylation
  • Vascular Endothelial Growth Factors
  • Messenger RNA
  • Carrier Proteins
  • Cell Line
  • Semaphorin-3A
  • Neuropilin-1
  • Young Adult
  • Signal Transduction
  • Cancer Gene Expression Regulation
  • Gene Expression Profiling
  • Sympathetic Nervous System
  • VEGFA
  • Chromosome Deletion
  • Prostate Cancer
  • Protein Processing, Post-Translational
  • RNA Interference
  • Angiogenesis
  • Sequence Homology
Tag cloud generated 15 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: SEMA3A (cancer-related)

Sorber R, Teper Y, Abisoye-Ogunniyan A, et al.
Whole Genome Sequencing of Newly Established Pancreatic Cancer Lines Identifies Novel Somatic Mutation (c.2587G>A) in Axon Guidance Receptor Plexin A1 as Enhancer of Proliferation and Invasion.
PLoS One. 2016; 11(3):e0149833 [PubMed] Free Access to Full Article Related Publications
The genetic profile of human pancreatic cancers harbors considerable heterogeneity, which suggests a possible explanation for the pronounced inefficacy of single therapies in this disease. This observation has led to a belief that custom therapies based on individual tumor profiles are necessary to more effectively treat pancreatic cancer. It has recently been discovered that axon guidance genes are affected by somatic structural variants in up to 25% of human pancreatic cancers. Thus far, however, some of these mutations have only been correlated to survival probability and no function has been assigned to these observed axon guidance gene mutations in pancreatic cancer. In this study we established three novel pancreatic cancer cell lines and performed whole genome sequencing to discover novel mutations in axon guidance genes that may contribute to the cancer phenotype of these cells. We discovered, among other novel somatic variants in axon guidance pathway genes, a novel mutation in the PLXNA1 receptor (c.2587G>A) in newly established cell line SB.06 that mediates oncogenic cues of increased invasion and proliferation in SB.06 cells and increased invasion in 293T cells upon stimulation with the receptor's natural ligand semaphorin 3A compared to wild type PLXNA1 cells. Mutant PLXNA1 signaling was associated with increased Rho-GTPase and p42/p44 MAPK signaling activity and cytoskeletal expansion, but not changes in E-cadherin, vimentin, or metalloproteinase 9 expression levels. Pharmacologic inhibition of the Rho-GTPase family member CDC42 selectively abrogated PLXNA1 c.2587G>A-mediated increased invasion. These findings provide in-vitro confirmation that somatic mutations in axon guidance genes can provide oncogenic gain-of-function signals and may contribute to pancreatic cancer progression.

Yamada D, Kawahara K, Ozaki M, Maeda T
Tumor cell-derived secretory factor downregulates Semaphorin-3a in osteoblasts by activating mammalian target of rapamycin pathway.
Biosci Biotechnol Biochem. 2016; 80(5):942-4 [PubMed] Related Publications
We found that conditioned medium derived from Lewis Lung Carcinoma cells down-regulated Semaphorin3a (Sema3a) mRNA expression and increased the activity of mammalian target of rapamycin complex 1 (mTORC1) in osteoblast-like MC3T3-E1 cells. Furthermore, mTORC1 inhibition with rapamycin counteracted the effect of conditioned media on Sema3a mRNA expression. These results suggest that tumor cells decrease Sema3a mRNA expression in osteoblast in an mTORC1-dependent manner.

Wang Z, Chen J, Zhang W, et al.
Axon guidance molecule semaphorin3A is a novel tumor suppressor in head and neck squamous cell carcinoma.
Oncotarget. 2016; 7(5):6048-62 [PubMed] Free Access to Full Article Related Publications
Semaphorin3A (SEMA3A), an axon guidance molecule in the nervous system, plays an inhibitory role in oncogenesis. Here, we investigated the expression pattern and biological roles of SEMA3A in head and neck squamous cell carcinoma (HNSCC) by gain-of-function assays using adenovirus transfection and recombinant human SEMA3A protein. In addition, we explored the therapeutic efficacy of SEMA3A against HNSCC in vivo. We found that lower expression of SEMA3A correlated with shorter overall survival and had independent prognostic importance in patients with HNSCC. Both genetic and recombinant SEMA3A protein inhibited cell proliferation and colony formation and induced apoptosis, accompanied by decreased cyclin E, cyclin D, CDK2, CDK4 and CDK6 and increased P21, P27, activated caspase-5 and caspase-7. Moreover, over-expression of SEMA3A suppressed migration, invasion and epithelial-to-mesenchymal transition due in part to the inhibition of NF-κB and SNAI2 in HNSCC cell lines. Furthermore, intratumoral SEMA3A delivery significantly stagnated tumor growth in a xenograft model. Taken together, our results indicate that SEMA3A serves as a tumor suppressor during HNSCC tumorigenesis and a new target for the treatment of HNSCC.

Yang XH, Wang B, Cunningham JM
Identification of epigenetic modifications that contribute to pathogenesis in therapy-related AML: Effective integration of genome-wide histone modification with transcriptional profiles.
BMC Med Genomics. 2015; 8 Suppl 2:S6 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Therapy-related, secondary acute myeloid leukemia (t-AML) is an increasingly frequent complication of intensive chemotherapy. This malignancy is often characterized by abnormalities of chromosome 7, including large deletions or chromosomal loss. A variety of studies suggest that decreased expression of the EZH2 gene located at 7q36.1 is critical in disease pathogenesis. This histone methyltransferase has been implicated in transcriptional repression through modifying histone H3 on lysine 27 (H3k27). However, the critical target genes of EZH2 and their regulatory roles remain unclear.
METHOD: To characterize the subset of EZH2 target genes that might contribute to t-AML pathogenesis, we developed a novel computational analysis to integrate tissue-specific histone modifications and genome-wide transcriptional regulation. Initial integrative analysis utilized a novel "seq2gene" strategy to explore largely the target genes of chromatin immuneprecipitation sequencing (ChIP-seq) enriched regions. By combining seq2gene with our Phenotype-Genotype-Network (PGNet) algorithm, we enriched genes with similar expression profiles and genomic or functional characteristics into "biomodules".
RESULTS: Initial studies identified SEMA3A (semaphoring 3A) as a novel oncogenic candidate that is regulated by EZH2-silencing, using data derived from both normal and leukemic cell lines as well as murine cells deficient in EZH2. A microsatellite marker at the SEMA3A promoter has been associated with chemosensitivity and radiosensitivity. Notably, our subsequent studies in primary t-AML demonstrate an expected up-regulation of SEMA3A that is EZH2-modulated. Furthermore, we have identified three biomodules that are co-expressed with SEMA3A and up-regulated in t-AML, one of which consists of previously characterized EZH2-repressed gene targets. The other two biomodules include MAPK8 and TATA box targets. Together, our studies suggest an important role for EZH2 targets in t-AML pathogenesis that warrants further study.
CONCLUSION: These developed computational algorithms and systems biology strategies will enhance the knowledge discovery and hypothesis-driven analysis of multiple next generation sequencing data, for t-AML and other complex diseases.

Jiang H, Qi L, Wang F, et al.
Decreased semaphorin 3A expression is associated with a poor prognosis in patients with epithelial ovarian carcinoma.
Int J Mol Med. 2015; 35(5):1374-80 [PubMed] Related Publications
Semaphorin 3A (SEMA3A) was initially identified to play an important role in axonal guidance. Recently, SEMA3A has also been considered as a candidate tumor suppressor, since it is often downregulated in numerous types of cancer, including prostate cancer, breast cancer and glioma. However, the biological role of SEMA3A in ovarian cancer is not clear. In the present study, the expression of SEMA3A in ovarian cancer and normal ovarian epithelial tissues was detected by immunofluorescence, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting, and the associations between the expression of SEMA3A with the development of ovarian cancer, clinicopathological characteristics and survival were also analyzed. Results from immunofluorescence, RT‑qPCR and western blotting showed that SEMA3A is significantly downregulated in epithelial ovarian carcinoma compared to normal ovarian epithelial specimens (P<0.05). The expression levels of SEMA3A were lower in the cancer tissues with III/IV stage [the International Federation of Gynecology and Obstetrics (FIGO) stage], poor histological grade, lymph node metastasis and distant metastasis compared to that in the cancer tissues with I/II stage (FIGO), well histological grade, or without lymph node metastasis and distant metastasis (P<0.05). A decreased expression of SEMA3A is associated with a poor prognosis (P<0.001). The present findings suggest that decreased SEMA3A expression may be associated with the development of epithelial ovarian carcinoma, and therefore, SEMA3A may be a valuable prognostic marker, as well as a potential molecular therapy target for ovarian cancer patients.

Shostak K, Zhang X, Hubert P, et al.
NF-κB-induced KIAA1199 promotes survival through EGFR signalling.
Nat Commun. 2014; 5:5232 [PubMed] Free Access to Full Article Related Publications
Constitutive activation of EGFR- and NF-κB-dependent pathways is a hallmark of cancer, yet signalling proteins that connect both oncogenic cascades are poorly characterized. Here we define KIAA1199 as a BCL-3- and p65-dependent gene in transformed keratinocytes. KIAA1199 expression is enhanced on human papillomavirus (HPV) infection and is aberrantly expressed in clinical cases of cervical (pre)neoplastic lesions. Mechanistically, KIAA1199 binds Plexin A2 and protects from Semaphorin 3A-mediated cell death by promoting EGFR stability and signalling. Moreover, KIAA1199 is an EGFR-binding protein and KIAA1199 deficiency impairs EGF-dependent Src, MEK1 and ERK1/2 phosphorylations. Therefore, EGFR stability and signalling to downstream kinases requires KIAA1199. As such, KIAA1199 promotes EGF-mediated epithelial-mesenchymal transition (EMT). Taken together, our data define KIAA1199 as an oncogenic protein induced by HPV infection and constitutive NF-κB activity that transmits pro-survival and invasive signals through EGFR signalling.

Ruan SS, Li RC, Han Q, et al.
Expression and clinical significance of Semaphorin4D in non-small cell lung cancer and its impact on malignant behaviors of A549 lung cancer cells.
J Huazhong Univ Sci Technolog Med Sci. 2014; 34(4):491-6 [PubMed] Related Publications
This study aimed to explore Semaphrin4D (Sema4D) expression and clinical significance in non-small cell lung cancer (NSCLC), and to define the roles and mechanisms of Sema4D in regulating the malignant behaviors of A549 cells by small interfering RNA (siRNA). Firstly, immunohistochemistry revealed that Sema4D was more frequently expressed in NSCLC than in lung benign lesion (P<0.05) and its overexpression was associated with low differentiation (P<0.05), poor pTNM staging (P<0.05) and occurrence of lymph node (LN) metastasis (P<0.05). Endogenous Sema4D expression was suppressed by Sema4D siRNA in A549 cells overexpressing Sema4D. Protein levels of Sema4D, total Akt and p-Akt were examined by Western blotting. Cell proliferation, migration and invasion abilities were measured by MTT assay and Transwell assay respectively. Results showed that Sema4D siRNA significantly suppressed phosphorylation of AKT in A549 cells, but it did not alter total AKT expression. In addition, efficient down-regulation of SemaD significantly inhibit cell proliferation (P<0.05), migration (P<0.05) and invasion (P<0.05) in A549 cells. These findings suggest that Sema4D might serve as a reliable tool for early prediction of NSCLC poor prognosis. Sema4D could play an important role in promoting tumor proliferation, migration and metastasis in the NSCLC, by influencing the Akt protein phosphorylation. Inhibition of Sema4D may be a useful approach for the treatment of NSCLC.

Mishra R, Thorat D, Soundararajan G, et al.
Semaphorin 3A upregulates FOXO 3a-dependent MelCAM expression leading to attenuation of breast tumor growth and angiogenesis.
Oncogene. 2015; 34(12):1584-95 [PubMed] Related Publications
Semaphorin 3A (Sema 3A), a member of semaphorin family, serves as a guidance clue during embryonic development and is known as a candidate tumor suppressor that attenuates breast tumor progression by binding with its co-receptor, neuropilin-1 (NRP-1). However, the underlying mechanism by which Sema 3A suppresses breast tumor growth is still unexplored. In this study, we report that Sema 3A regulates phosphorylation and nuclear translocation of phosphatase and tensin homolog (PTEN) and FOXO 3a. Moreover, Sema 3A controls NRP-1-mediated PTEN-dependent FOXO 3a activation. Overexpression of PTEN and FOXO 3a enhances Sema 3A-induced attenuation of breast cancer cell migration. Chromatin immunoprecipitation and electrophoretic mobility shift assay data revealed that FOXO 3a regulates MelCAM at the transcriptional level. Furthermore, Sema 3A induces NRP-1-mediated MelCAM expression through PTEN and FOXO 3a. The data also showed that vascular endothelial growth factor-induced angiogenesis is inhibited by Sema 3A. Loss of or gain in function study revealed that Sema 3A modulates phosphorylation of PTEN and FOXO 3a and expression of MelCAM, leading to suppression of tumor growth and angiogenesis using in vivo mice model. Clinical specimen analysis revealed that reduced expression of Sema 3A and p-PTEN are correlated with enhanced breast cancer progression, further strengthening our in vitro and in vivo findings. Correlation of relapse-free survival of breast cancer patients (n=2878) with expression levels of Sema 3A, NRP-1, FOXO 3a and MelCAM were studied by Kaplan-Meier analysis. Statistical analysis revealed a close association between reduced expression of Sema 3A and MelCAM with that of poor patient's survival. Our study demonstrated a novel mechanism of regulation of tumor suppression by Sema 3A in coordination with a chain of tumor-suppressor genes, which in turn inhibits breast cancer cell migration, tumor growth and angiogenesis.

Deng BY, Hua YQ, Cai ZD
Establishing an osteosarcoma associated protein-protein interaction network to explore the pathogenesis of osteosarcoma.
Eur J Med Res. 2013; 18:57 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The aim of this study was to establish an osteosarcoma (OS) associated protein-protein interaction network and explore the pathogenesis of osteosarcoma.
METHODS: The gene expression profile GSE9508 was downloaded from the Gene Expression Omnibus database, including five samples of non-malignant bone (the control), seven samples for non-metastatic patients (six of which were analyzed in duplicate), and 11 samples for metastatic patients (10 of which were analyzed in duplicate). Differentially expressed genes (DEGs) between osteosarcoma and control samples were identified by packages in R with the threshold of |logFC (fold change)| > 1 and false discovery rate < 0.05. Osprey software was used to construct the interaction network of DEGs, and genes at protein-protein interaction (PPI) nodes with high degrees were identified. The Database for Annotation, Visualization and Integrated Discovery and WebGestalt software were then used to perform functional annotation and pathway enrichment analyses for PPI networks, in which P < 0.05 was considered statistically significant.
RESULTS: Compared to the control samples, the expressions of 42 and 341 genes were altered in non-metastatic OS and metastatic OS samples, respectively. A total of 15 significantly enriched functions were obtained with Gene Ontology analysis (P < 0.05). The DEGs were classified and significantly enriched in three pathways, including the tricarboxylic acid cycle, lysosome and axon guidance. Genes such as HRAS, IDH3A, ATP6ap1, ATP6V0D2, SEMA3F and SEMA3A were involved in the enriched pathways.
CONCLUSIONS: The hub genes from metastatic OS samples are not only bio-markers of OS, but also help to improve therapies for OS.

Rosenberg EE, Prudnikova TY, Zabarovsky ER, et al.
D-glucuronyl C5-epimerase cell type specifically affects angiogenesis pathway in different prostate cancer cells.
Tumour Biol. 2014; 35(4):3237-45 [PubMed] Related Publications
D-glucuronyl C5-epimerase (GLCE) is involved in breast and lung carcinogenesis as a potential tumor suppressor gene, acting through inhibition of tumor angiogenesis and invasion/metastasis pathways. However, in prostate tumors, increased GLCE expression is associated with advanced disease, suggesting versatile effects of GLCE in different cancers. To investigate further the potential cancer-promoting effect of GLCE in prostate cancer, GLCE was ectopically re-expressed in morphologically different LNCaP and PC3 prostate cancer cells. Transcriptional profiles of normal PNT2 prostate cells, LNCaP, PC3 and DU145 prostate cancer cells, and GLCE-expressing LNCaP and PC3 cells were determined. Comparative analysis revealed the genes whose expression was changed in prostate cancer cells compared with normal PNT2 cells, and those differently expressed between the cancer cell lines (ACTA2, IL6, SERPINE1, TAGLN, SEMA3A, and CDH2). GLCE re-expression influenced mainly angiogenesis-involved genes (ANGPT1, SERPINE1, IGF1, PDGFB, TNF, IL8, TEK, IFNA1, and IFNB1) but in a cell type-specific manner (from basic deregulation of angiogenesis in LNCaP cells to significant activation in PC3 cells). Invasion/metastasis pathway was also affected (MMP1, MMP2, MMP9, S100A4, ITGA1, ITGB3, ERBB2, and FAS). The obtained results suggest activation of angiogenesis as a main molecular mechanism of pro-oncogenic effect of GLCE in prostate cancer. GLCE up-regulation plus expression pattern of a panel of six genes, discriminating morphologically different prostate cancer cell sub-types, is suggested as a potential marker of aggressive prostate cancer.

Nassehi D
Intracranial meningiomas, the VEGF-A pathway, and peritumoral brain oedema.
Dan Med J. 2013; 60(4):B4626 [PubMed] Related Publications
Meningiomas are the second-most common intracranial tumours in adults. They are derived from the arachnoid cells, and although approximately 90% of meningiomas are benign, more than half of all meningiomas develop peritumoral brain oedema (PTBE), which increases morbidity. The PTBE can be treated with steroid therapy, but this treatment is not specific, is not always effective, and involves long-term side-effects. Meningiomas are treated with radiation therapy, stereotactic radio-surgery or surgical resection. At the moment surgical resection is the only definite treatment, and the removal of the tumour also removes the PTBE. Based on the localization of the meningioma, surgery can be complicated. Although PTBE around meningiomas is frequent, the mechanisms behind its development are not clearly understood. It is believed that due to tumour growth and local tissue hypoxia, angiogenesis is increased and leads to the formation of PTBE. The angiogenic protein vascular endothelial growth factor A (VEGF-A) is believed to be involved in the formation of PTBE around meningiomas, as several studies have found that it is increased in meningiomas with PTBE. VEGF-A is also known as vascular permeability factor due to its ability to increase the permeability of capillaries. Paper I examines the VEGF-A protein and mRNA levels in 101 intracranial meningiomas. The PTBE is quantified on MRI, and capillary length and tumour water content are measured and compared to control brain tissue. Possible co-factors to PTBE like meningioma localization and subtypes are also examined. Forty-three of the patients have primary, solitary, supratentorial meningiomas with PTBE. The correlation between PTBE or edema index with the VEGF-A protein and mRNA, capillary length, and tumour water content is investigated in these patients. A novel method is used for mRNA quantification. It involves direct amplification of the mRNA with probes and branched DNA in order to produce a chemiluminescence signal that can be measured using a luminometer. The paper shows that the oedema index is correlated to the VEGF-A protein and mRNA, and that capillary length is correlated to the PTBE. It also finds that VEGF-A protein and mRNA, capillary length and water content is increased in meningiomas compared to control tissue, suggesting that VEGF-A is produced in, and possibly secreted from the meningiomas. In addition, supratentorial meningiomas are shown to have larger PTBE compared to infratentorial meningiomas, suggesting that infratentorial meningiomas are diagnosed and removed earlier, due to earlier symptom development based on the anatomical features of the fossa posterior. Finally, a gender-specific difference in tumour water content and VEGF-A protein is revealed (higher and lower in females, respectively). Paper II is a method-comparison study pitting the chemiluminescence assay against the often used quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR) assay. In RT-qPCR, RNA is isolated, measured, reverse transcribed, purified, amplified via real-time PCR, and analyzed. The method is robust and reliable, albeit laborious to some extent. The chemiluminescence assay detects RNA directly without the need for RNA purification, complement DNA synthesis or cyclic amplification. By comparing the output of the two protocols to a dilution series ranging from 1 to 128 times of the homogenized samples, the precision of the protocols is measured. Furthermore, VEGF-A/GAPDH ratios are quantified for 15 tissue samples and the results compared between the two protocols, showing significant correlation. The study finds that the chemiluminescence assay is competitive to RT-qPCR, and reflects a similar pattern in gene expression measurement with a similar precision. Whether one method or the other should be used depends on the variability of the samples, budget, and time. RT-qPCR has a much wider dynamic range, and is preferable in case of significant sample inter-variability. It is also less expensive, and gives the user more flexibility as homemade reagents can be used. On the other hand, the chemiluminescence assay is straight forward, requires less hands-on-time, and can be used on formalin-fixed and paraffin-embedded (FFPE) tissue. Paper III continues the investigations in paper I. The sample size is increased so that 22 angiomatous and secretory meningiomas are compared to 40 non-angiomatous meningiomas and 10 control brain tissue samples. Angiomatous and secretory meningiomas are chosen because they are known to have larger PTBE compared to other meningiomas. In addition to VEGF-A, capillary length, and PTBE, the VEGF-A tyrosine kinase receptor VEGFR-2 mRNA and protein levels are also examined. VEGFR-2 is a transmembrane receptor found on endothelial cells. It binds VEGF-A and thereby increases angiogenesis. VEGFR-2's co-receptor neuropilin-1 is also examined. Neuropilin-1 is an agonist of angiogenesis through complex-binding of VEGF-A, but it can also work as an inhibitor through competitive binding of semaphorin-3A. The complex binding of semaphorin-3A to neuropilin-1 can also induce endothelial cell apoptosis, thus working as an antagonist of angiogenesis. The study finds that VEGF-A mRNA, VEGF-A protein, and neuropilin-1 mRNA are higher in angiomatous and non-angiomatous meningiomas compared to controls. VEGFR-2 protein is higher, and neuropilin-1 protein lower in angiomatous meningiomas compared to controls. The mean capillary length is 3614 mm/mm3 in angiomatous, 605 mm/mm3 in non-angiomatous meningiomas, and 229 mm/mm3 in the controls. Non-angiomatous and angiomatous meningioma patients have equally sized tumours. The mean PTBE around the angiomatous meningiomas is 695 cm3, i.e. 477 cm3 larger than the non-angiomatous meningiomas (p = 0.0045), and the mean oedema index is twice the size compared to the non-angiomatous meningiomas. Further comparison between the two meningioma groups shows that mean VEGF-A mRNA, VEGFR-2 protein, and neuropilin-1 mRNA is significantly higher and neuropilin-1 protein is lower in the angiomatous meningiomas. We believe that the VEGF-A pathway participates in the formation of PTBE in meningiomas by inducing formation of "leaky" capillaries, resulting in secretion of VEGF-A and plasma to the peritumoural brain tissue. It may therefore be worth pursuing therapies targeted directly against VEGF-A and its receptors through drugs like bevacizumab, sorafenib, sunitifib, and cediranib.

Carrer A, Moimas S, Zacchigna S, et al.
Neuropilin-1 identifies a subset of bone marrow Gr1- monocytes that can induce tumor vessel normalization and inhibit tumor growth.
Cancer Res. 2012; 72(24):6371-81 [PubMed] Related Publications
Improving tumor perfusion, thus tempering tumor-associated hypoxia, is known to impair cancer progression. Previous work from our laboratory has shown that VEGF-A165 and semaphorin 3A (Sema3A) promote vessel maturation through the recruitment of a population of circulating monocytes expressing the neuropilin-1 (Nrp1) receptor (Nrp1-expressing monocytes; NEM). Here, we define the characteristics of bone marrow NEMs and assess whether these cells might represent an exploitable tool to induce tumor vessel maturation. Gene expression signature and surface marker analysis have indicated that NEMs represent a specific subset of CD11b+ Nrp1+ Gr1- resident monocytes, distinctively recruited by Sema3A. NEMs were found to produce several factors involved in vessel maturation, including PDGFb, TGF-β, thrombospondin-1, and CXCL10; consistently, they were chemoattractive for vascular smooth muscle cells in vitro. When directly injected into growing tumors, NEMs, isolated either from the bone marrow or from Sema3A-expressing muscles, exerted antitumor activity despite having no direct effects on the proliferation of tumor cells. NEM inoculation specifically promoted mural cell coverage of tumor vessels and decreased vascular leakiness. Tumors treated with NEMs were smaller, better perfused and less hypoxic, and had a reduced level of activation of HIF-1α. We conclude that NEMs represent a novel, unique population of myeloid cells that, once inoculated into a tumor, induce tumor vessel normalization and inhibit tumor growth.

Zhou X, Ma L, Li J, et al.
Effects of SEMA3G on migration and invasion of glioma cells.
Oncol Rep. 2012; 28(1):269-75 [PubMed] Related Publications
Glioblastoma multiforme is the most aggressive type of brain tumor with a strong ability to invade and migrate into surrounding normal brain tissues, leading to high tumor recurrence and mortality. Most of class-3 semaphorins, especially SEMA3A, SEMA3B and SEMA3F, have been reported to have strong tumor inhibition ability, but the role of SEMA3G in tumor biology is largely unknown. We report here that SEMA3G possesses anti-migration and anti-invasion ability. To determine the potential effects of SEMA3G on migratory and invasive ability, we generated stable SEMA3G expression U251MG cells. We found that stably overexpressed SEMA3G inhibited the migratory and invasive behavior of U251MG cells. In addition, treatment with SEMA3G conditioned media also decreased the migratory and invasive ability of parental U251MG cells. Furthermore, SEMA3G also inhibited the activity of MMP2, an index of tumor invasion ability. Thus, our results suggest that SEMA3G inhibited tumor cell migration and invasion, which may be obtained through cell autonomous or paracrine mechanisms, and SEMA3G is a potential target for antitumor migration and invasion.

Agesen TH, Sveen A, Merok MA, et al.
ColoGuideEx: a robust gene classifier specific for stage II colorectal cancer prognosis.
Gut. 2012; 61(11):1560-7 [PubMed] Related Publications
BACKGROUND AND AIMS: Several clinical factors have an impact on prognosis in stage II colorectal cancer (CRC), but as yet they are inadequate for risk assessment. The present study aimed to develop a gene expression classifier for improved risk stratification of patients with stage II CRC.
METHODS: 315 CRC samples were included in the study. Gene expression measurements from 207 CRC samples (stage I-IV) from two independent Norwegian clinical series were obtained using Affymetrix exon-level microarrays. Differentially expressed genes between stage I and stage IV samples from the test series were identified and used as input for L1 (lasso) penalised Cox proportional hazards analyses of patients with stage II CRC from the same series. A second validation was performed in 108 stage II CRC samples from other populations (USA and Australia).
RESULTS: An optimal 13-gene expression classifier (PIGR, CXCL13, MMP3, TUBA1B, SESN1, AZGP1, KLK6, EPHA7, SEMA3A, DSC3, CXCL10, ENPP3, BNIP3) for prediction of relapse among patients with stage II CRC was developed using a consecutive Norwegian test series from patients treated according to current standard protocols (n=44, p<0.001, HR=18.2), and its predictive value was successfully validated for patients with stage II CRC in a second Norwegian CRC series collected two decades previously (n=52, p=0.02, HR=3.6). Further validation of the classifier was obtained in a recent external dataset of patients with stage II CRC from other populations (n=108, p=0.001, HR=6.5). Multivariate Cox regression analyses, including all three sample series and various clinicopathological variables, confirmed the independent prognostic value of the classifier (p≤0.004). The classifier was shown to be specific to stage II CRC and does not provide prognostic stratification of patients with stage III CRC.
CONCLUSION: This study presents the development and validation of a 13-gene expression classifier, ColoGuideEx, for prognosis prediction specific to patients with stage II CRC. The robustness was shown across patient series, populations and different microarray versions.

Yoshikawa Y, Sato A, Tsujimura T, et al.
Frequent deletion of 3p21.1 region carrying semaphorin 3G and aberrant expression of the genes participating in semaphorin signaling in the epithelioid type of malignant mesothelioma cells.
Int J Oncol. 2011; 39(6):1365-74 [PubMed] Related Publications
Array-based comparative genomic hybridization analysis was performed on 21 malignant mesothelioma (MM) samples (16 primary cell cultures and 5 cell lines) and two reactive mesothelial hyperplasia (RM) primary cell cultures. The RM samples did not have any genomic losses or gains. In MM samples, deletions in 1p, 3p21, 4q, 9p21, 16p13 and 22q were detected frequently. We focused on 3p21 because this deletion was specific to the epithelioid type. Especially, a deletion in 3p21.1 region carrying seven genes including SEMA3G was found in 52% of MM samples (11 of 14 epithelioid samples). The allele loss of 3p21.1 might be a good marker for the epithelioid MM. A homozygous deletion in this region was detected in two MM primary cell cultures. A heterozygous deletion detected in nine samples contained the 3p21.1 region and 3p21.31 one carrying the candidate tumor suppressor genes such as semaphorin 3F (SEMA3F), SEMA3B and Ras association (RalGDS/AF-6) domain family member 1 (RASSF1A). SEMA3B, 3F and 3G are class 3 semaphorins and inhibit growth by competing with vascular endothelial growth factor (VEGF) through binding to neuropilin. All MM samples downregulated the expression of more than one gene for SEMA3B, 3F and 3G when compared with Met5a, a normal pleura-derived cell line. Moreover, in 12 of 14 epithelioid MM samples the expression level of SEMA3A was lower than that in Met5a and the two RM samples. An augmented expression of VEGFA was detected in half of the MM samples. The expression ratio of VEGFA/SEMA3A was significantly higher in the epithelioid MMs than in Met5a, RMs and the non-epithelioid MMs. Our data suggest that the downregulated expression of SEMA3A and several SEMA3s results in a loss of inhibitory activities in tumor angiogenesis and tumor growth of VEGFA; therefore, it may play an important role on the pathogenesis of the epithelioid type of MM.

Larsson M, Duffy DL, Zhu G, et al.
GWAS findings for human iris patterns: associations with variants in genes that influence normal neuronal pattern development.
Am J Hum Genet. 2011; 89(2):334-43 [PubMed] Free Access to Full Article Related Publications
Human iris patterns are highly variable. The origins of this variation are of interest in the study of iris-related eye diseases and forensics, as well as from an embryological developmental perspective, with regard to their possible relationship to fundamental processes of neurodevelopment. We have performed genome-wide association scans on four iris characteristics (crypt frequency, furrow contractions, presence of peripupillary pigmented ring, and number of nevi) in three Australian samples of European descent. Both the discovery (n = 2121) and replication (n = 499 and 73) samples showed evidence for association between (1) crypt frequency and variants in the axonal guidance gene SEMA3A (p = 6.6 × 10(-11)), (2) furrow contractions and variants within the cytoskeleton gene TRAF3IP1 (p = 2.3 × 10(-12)), and (3) the pigmented ring and variants in the well-known pigmentation gene SLC24A4 (p = 7.6 × 10(-21)). These replicated findings individually accounted for around 1.5%-3% of the variance for these iris characteristics. Because both SEMA3A and TRAFIP1 are implicated in pathways that control neurogenesis, neural migration, and synaptogenesis, we also examined the evidence of enhancement among such genes, finding enrichment for crypts and furrows. These findings suggest that genes involved in normal neuronal pattern development may also influence tissue structures in the human iris.

Kigel B, Rabinowicz N, Varshavsky A, et al.
Plexin-A4 promotes tumor progression and tumor angiogenesis by enhancement of VEGF and bFGF signaling.
Blood. 2011; 118(15):4285-96 [PubMed] Related Publications
Plexin-A4 is a receptor for sema6A and sema6B and associates with neuropilins to transduce signals of class-3 semaphorins. We observed that plexin-A1 and plexin-A4 are required simultaneously for transduction of inhibitory sema3A signals and that they form complexes. Unexpectedly, inhibition of plexin-A1 or plexin-A4 expression in endothelial cells using specific shRNAs resulted in prominent plexin type specific rearrangements of the actin cytoskeleton that were accompanied by inhibition of bFGF and VEGF-induced cell proliferation. The two responses were not interdependent since silencing plexin-A4 in U87MG glioblastoma cells inhibited cell proliferation and strongly inhibited the formation of tumors from these cells without affecting cytoskeletal organization. Plexin-A4 formed stable complexes with the FGFR1 and VEGFR-2 tyrosine-kinase receptors and enhanced VEGF-induced VEGFR-2 phosphorylation in endothelial cells as well as bFGF-induced cell proliferation. We also obtained evidence suggesting that some of the pro-proliferative effects of plexin-A4 are due to transduction of autocrine sema6B-induced pro-proliferative signals, since silencing sema6B expression in endothelial cells and in U87MG cells mimicked the effects of plexin-A4 silencing and also inhibited tumor formation from the U87MG cells. Our results suggest that plexin-A4 may represent a target for the development of novel anti-angiogenic and anti-tumorigenic drugs.

Casazza A, Fu X, Johansson I, et al.
Systemic and targeted delivery of semaphorin 3A inhibits tumor angiogenesis and progression in mouse tumor models.
Arterioscler Thromb Vasc Biol. 2011; 31(4):741-9 [PubMed] Related Publications
OBJECTIVE: The role of semaphorins in tumor progression is still poorly understood. In this study, we aimed at elucidating the regulatory role of semaphorin 3A (SEMA3A) in primary tumor growth and metastatic dissemination.
METHODS AND RESULTS: We used 3 different experimental approaches in mouse tumor models: (1) overexpression of SEMA3A in tumor cells, (2) systemic expression of SEMA3A following liver gene transfer in mice, and (3) tumor-targeted release of SEMA3A using gene modified Tie2-expressing monocytes as delivery vehicles. In each of these experimental settings, SEMA3A efficiently inhibited tumor growth by inhibiting vessel function and increasing tumor hypoxia and necrosis, without promoting metastasis. We further show that the expression of the receptor neuropilin-1 in tumor cells is required for SEMA3A-dependent inhibition of tumor cell migration in vitro and metastatic spreading in vivo.
CONCLUSIONS: In sum, both systemic and tumor-targeted delivery of SEMA3A inhibits tumor angiogenesis and tumor growth in multiple mouse models; moreover, SEMA3A inhibits the metastatic spreading from primary tumors. These data support the rationale for further investigation of SEMA3A as an anticancer molecule.

Maione F, Molla F, Meda C, et al.
Semaphorin 3A is an endogenous angiogenesis inhibitor that blocks tumor growth and normalizes tumor vasculature in transgenic mouse models.
J Clin Invest. 2009; 119(11):3356-72 [PubMed] Free Access to Full Article Related Publications
Tumor growth and progression rely upon angiogenesis, which is regulated by pro- and antiangiogenic factors, including members of the semaphorin family. By analyzing 3 different mouse models of multistep carcinogenesis, we show here that during angiogenesis, semaphorin 3A (Sema3A) is expressed in ECs, where it serves as an endogenous inhibitor of angiogenesis that is present in premalignant lesions and lost during tumor progression. Pharmacologic inhibition of endogenous Sema3A during the angiogenic switch, the point when pretumoral lesions initiate an angiogenic phase that persists throughout tumor growth, enhanced angiogenesis and accelerated tumor progression. By contrast, when, during the later stages of carcinogenesis following endogenous Sema3A downmodulation, Sema3A was ectopically reintroduced into islet cell tumors by somatic gene transfer, successive waves of apoptosis ensued, first in ECs and then in tumor cells, resulting in reduced vascular density and branching and inhibition of tumor growth and substantially extended survival. Further, long-term reexpression of Sema3A markedly improved pericyte coverage of tumor blood vessels, something that is thought to be a key property of tumor vessel normalization, and restored tissue normoxia. We conclude, therefore, that Sema3A is an endogenous and effective antiangiogenic agent that stably normalizes the tumor vasculature.

Pan SH, Chao YC, Chen HY, et al.
Long form collapsin response mediator protein-1 (LCRMP-1) expression is associated with clinical outcome and lymph node metastasis in non-small cell lung cancer patients.
Lung Cancer. 2010; 67(1):93-100 [PubMed] Related Publications
Collapsin response mediator protein (CRMP) family proteins are cytosolic phosphoproteins involved in semaphorin 3A-mediated neuronal cell growth cone collapse and cancer invasion. We identified a novel human isoform of CRMP family proteins named long form CRMP-1 (LCRMP-1), which was different from the known invasion suppressor, CRMP-1, in its molecular weight and the N-terminal exon-1. This study was aimed to elucidate the clinical significance of LCRMP-1 in non-small cell lung cancer (NSCLC) patients. Full-length human LCRMP-1 was cloned from lung adenocarcinoma based on the Expressed Sequence Tags (EST) database. We generated LCRMP-1 specific antibody and subsequent in vitro and in vivo invasion assays showed positive correlations between LCRMP-1 expression and lung cancer cell invasiveness. We further demonstrated that high LCRMP-1 mRNA expressions were associated with poor overall and disease-free survivals (P=0.004 and 0.006, respectively, log-rank test) in 72 NSCLC patients. The results were confirmed in an independent cohort of 54 NSCLC patients by immunohistochemistry (P=0.032, log-rank test). The metastatic lymph nodes showed higher LCRMP-1 expressions as compared with the paired primary lung tumors (P=0.012, McNemar's test). In conclusion, LCRMP-1 was a cancer invasion enhancer that could be a novel prognostic biomarker in NSCLC.

Kigel B, Varshavsky A, Kessler O, Neufeld G
Successful inhibition of tumor development by specific class-3 semaphorins is associated with expression of appropriate semaphorin receptors by tumor cells.
PLoS One. 2008; 3(9):e3287 [PubMed] Free Access to Full Article Related Publications
The class-3 semaphorins (sema3s) include seven family members. Six of them bind to neuropilin-1 (np1) or neuropilin-2 (np2) receptors or to both, while the seventh, sema3E, binds to the plexin-D1 receptor. Sema3B and sema3F were previously characterized as tumor suppressors and as inhibitors of tumor angiogenesis. To determine if additional class-3 semaphorins such as sema3A, sema3D, sema3E and sema3G possess anti-angiogenic and anti-tumorigenic properties, we expressed the recombinant full length semaphorins in four different tumorigenic cell lines expressing different combinations of class-3 semaphorin receptors. We show for the first time that sema3A, sema3D, sema3E and sema3G can function as potent anti-tumorigenic agents. All the semaphorins we examined were also able to reduce the concentration of tumor associated blood vessels although the potencies of the anti-angiogenic effects varied depending on the tumor cell type. Surprisingly, there was little correlation between the ability to inhibit tumor angiogenesis and their anti-tumorigenic activity. None of the semaphorins inhibited the adhesion of the tumor cells to plastic or fibronectin nor did they modulate the proliferation of tumor cells cultured in cell culture dishes. However, various semaphorins were able to inhibit the formation of soft agar colonies from tumor cells expressing appropriate semaphorin receptors, although in this case too the inhibitory effect was not always correlated with the anti-tumorigenic effect. In contrast, the anti-tumorigenic effect of each of the semaphorins correlated very well with tumor cell expression of specific signal transducing receptors for particular semaphorins. This correlation was not broken even in cases in which the tumor cells expressed significant concentrations of endogenous semaphorins. Our results suggest that combinations of different class-3 semaphorins may be more effective than single semaphorins in cases in which tumor cells express more than one type of semaphorin receptors.

Pan H, Wanami LS, Dissanayake TR, Bachelder RE
Autocrine semaphorin3A stimulates alpha2 beta1 integrin expression/function in breast tumor cells.
Breast Cancer Res Treat. 2009; 118(1):197-205 [PubMed] Free Access to Full Article Related Publications
The axon repulsion factor semaphorin3A (SEMA3A) and its receptor neuropilin-1 (NP-1) are expressed in breast tumor cells, and function as suppressors of tumor cell migration. Based on the knowledge that both SEMA3A and the alpha2beta1 integrin suppress breast tumor cell migration, we studied the impact of SEMA3A signaling on alpha2beta1 integrin expression/function. The incubation of breast tumor cells with SEMA3A increased alpha2 and beta1 integrin levels, and stimulated tumor cell adhesion to the alpha2beta1-binding matrix protein collagen I. Conversely, reducing SEMA3A expression in breast tumor cells decreased alpha2beta1 levels and collagen adhesion. The ability of SEMA3A to increase tumor cell adhesion to collagen was dependent on both the SEMA3A receptor NP-1 and the glycogen synthase kinase-3. The incubation of breast tumor cells with SEMA3A disrupted the actin cytoskeleton, and reduced both tumor cell migratory and invasive behavior. Importantly, using an alpha2beta1-neutralizing antibody, we demonstrated that SEMA3A suppression of tumor cell migration is dependent on alpha2beta1. Our studies indicate that expression of the alpha2beta1 integrin, a suppressor of metastatic breast tumor growth, is stimulated in breast tumor cells by an autocrine SEMA3A pathway.

Müller MW, Giese NA, Swiercz JM, et al.
Association of axon guidance factor semaphorin 3A with poor outcome in pancreatic cancer.
Int J Cancer. 2007; 121(11):2421-33 [PubMed] Related Publications
Neural alterations and aberrantly expressed nerve-specific factors promoting tumor progression are known to contribute to pancreatic cancer's extremely poor prognosis. Despite hints that axon guidance factor semaphorin 3A (SEMA3A) may function as a tumor inhibitor, its clinical importance and therapeutic potential have not yet been explored. The present study investigated the role of SEMA3A and its receptors-plexins A1-A4 (PLXNA1-A4) and neuropilin-1 (NRP1)-in pancreatic cancer. QRT-PCR and immunohistochemical analyses revealed overexpression of SEMA3A, NRP1 and PLXNA1 in metaplastic ducts, malignant cells and nerves of cancerous specimens, and showed that elevated levels of corresponding mRNA (6.8-fold, 2.0-fold and 1.5-fold, respectively) clearly correlated with negative clinicopathological manifestations such as shorter survival (SEMA3A and PLXNA1) and a lesser degree of tumor differentiation (NRP1) in Stages I-III patients. High SEMA3A expression in pancreata of Stage IV M1 patients and in peritoneal metastases, and consequent functional studies indicated that poor clinical outcome might be related to the ability of SEMA3A to promote dissemination and invasiveness of pancreatic cancer cells through activation of multiple pathways involving Rac1, GSK3b or p42/p44 MAPK, but not E- to N-cadherin switch, MMP-9 or VEGF induction. Thus, this study is the first to quantify expression of the SEMA3A system in human malignancy and to show that overexpression of SEMA3A by nerves and transformed cells leads to a SEMA3A-rich environment which may favor malignant activities of tumor cells. Furthermore, negative clinicopathological correlations suggest that SEMA3A might represent a novel intervention target but not a treatment option for pancreatic cancer patients.

Herman JG, Meadows GG
Increased class 3 semaphorin expression modulates the invasive and adhesive properties of prostate cancer cells.
Int J Oncol. 2007; 30(5):1231-8 [PubMed] Related Publications
The class 3 semaphorins, sema3A and sema3C, provide important guidance cues in cell development and in cancer; however, the role of these semaphorins in prostate cancer is not known. We report here that sema3A transfected cells exhibit decreased invasion and adhesion in Matrigel-based assays and that sema3C transfected cells exhibit increased invasive and adhesive characteristics. Important adhesion proteins were differentially modulated in sema3A and sema3C cells in a manner consistent with their subsequent invasive and adhesive characteristics. E-cadherin expression as determined by Western blot analysis was strongly upregulated in sema3A transfected cells, but strongly downregulated in sema3C transfected cells compared to untransfected and mock empty vector-transfected PC-3 cells. beta-catenin levels were not changed in sema3A transfected cells; however, sema3C transfected cells had lower expression of this protein. Sema3C transfected cells exhibited greater cellular membrane expression of certain alpha integrins as compared to untransfected and sema3A transfected cells, a characteristic associated with increased adhesion and invasion. These data indicate that the invasive ability of sema3A and sema3C transfected PC-3 cells is, in part, correlated with adhesion protein expression and adhesive ability to constituents of neighboring cells and the extracellular matrix.

Hu B, Guo P, Bar-Joseph I, et al.
Neuropilin-1 promotes human glioma progression through potentiating the activity of the HGF/SF autocrine pathway.
Oncogene. 2007; 26(38):5577-86 [PubMed] Free Access to Full Article Related Publications
Neuropilin-1 (NRP1) functions as a coreceptor through interaction with plexin A1 or vascular endothelial growth factor (VEGF) receptor during neuronal development and angiogenesis. NRP1 potentiates the signaling pathways stimulated by semaphorin 3A and VEGF-A in neuronal and endothelial cells, respectively. In this study, we investigate the role of tumor cell-expressed NRP1 in glioma progression. Analyses of human glioma specimens (WHO grade I-IV tumors) revealed a significant correlation of NRP1 expression with glioma progression. In tumor xenografts, overexpression of NRP1 by U87MG gliomas strongly promoted tumor growth and angiogenesis. Overexpression of NRP1 by U87MG cells stimulated cell survival through the enhancement of autocrine hepatocyte growth factor/scatter factor (HGF/SF)/c-Met signaling. NRP1 not only potentiated the activity of endogenous HGF/SF on glioma cell survival but also enhanced HGF/SF-promoted cell proliferation. Inhibition of HGF/SF, c-Met and NRP1 abrogated NRP1-potentiated autocrine HGF/SF stimulation. Furthermore, increased phosphorylation of c-Met correlated with glioma progression in human glioma biopsies in which NRP1 is upregulated and in U87MG NRP1-overexpressing tumors. Together, these data suggest that tumor cell-expressed NRP1 promotes glioma progression through potentiating the activity of the HGF/SF autocrine c-Met signaling pathway, in addition to enhancing angiogenesis, suggesting a novel mechanism of NRP1 in promoting human glioma progression.

Catalano A, Caprari P, Moretti S, et al.
Semaphorin-3A is expressed by tumor cells and alters T-cell signal transduction and function.
Blood. 2006; 107(8):3321-9 [PubMed] Related Publications
An important aspect of tumor progression is the ability of cancer cells to escape detection and clearance by the immune system. Recent studies suggest that several tumors express soluble factors interfering with the immune response. Here, we show that semaphorin-3A (Sema-3A), a secreted member of the semaphorin family involved in axonal guidance, organogenesis, and angiogenesis, is highly expressed in several tumor cells. Conditioned media of Sema-3A-transfected COS-7 cells or human recombinant Sema-3A inhibited primary human T-cell proliferation and cytokines production under anti-CD3 plus anti-CD28 stimulating conditions. Sema-3A also inhibited the activation of nonspecific cytotoxic activity in mixed lymphocyte culture (MLC), as measured against K-562 cells. In contrast, suppression of Sema-3A in tumor cells with a small interfering RNA (siRNA) augmented T-cell activation. The inhibitory effect of Sema-3A in T cells is mediated by blockade of Ras/mitogen-activated protein kinase (MAPK) signaling pathway. The presence of Sema-3A increased the activation of the Ras family small GTPase Rap1 and introduction of the dominant-negative mutant of Rap1 (Rap1N17) blunted the immunoinhibitory effects of Sema-3A. These results suggest that Sema-3A inhibits primary T-cell activation and imply that it can contribute to the T-cell dysfunction in the tumor microenvironment.

Wang Z, Li Y, Wu X, et al.
KDR and Sema3 genes expression in bone marrow stromal cells and hematopoietic cells from leukemia patients and normal individuals.
Hematology. 2005; 10(4):307-12 [PubMed] Related Publications
Kinase domain receptor (KDR) and Semaphorin3 (Sema3) have a functional relationship and are expressed in human bone marrow (BM). We cultured in vitro bone marrow stromal cells (BMSCs) and collected nonadherent cells from patients with acute myeloid leukemia (AML), chronic myelogenous leukemia (CML), acute lymphoblastic leukemia (ALL) and normal individuals. Reverse transcriptase polymerase chain reaction enzyme-linked immunosorbent assay (RT-PCR-ELISA) was performed to examine KDR and Sema3 genes expression, using beta2 microglobulin as an internal reference. KDR expression ratio in normal control BMSCs (97.0%, 32/33) was higher than in its corresponding nonadherent cells (70.8%, 17/24). KDR expression levels in ALL BMSCs and AML nonadherent cells were significantly higher than in normal controls. Sema3 expression ratios in nonadherent cells from AML (78.6%, 11/14) and CML (71.4%, 10/14) were both significantly lower than in normal control (100%, 27/27), its expression levels were also significantly lower than in normal control. Sema3 expression level in normal BMSCs was significantly lower than in nonadherent cells. Sema3 and KDR genes expression levels displayed a significantly positive correlation in normal control and ALL nonadherent cells (r=0.703, P=0.002; r=0.999, P=0.001). These results suggests that KDR may play a critical role in sustaining the hematopoietic microenvironment due to its high expression, and that KDR may be involved in pathogenesis of AML and ALL. Sema3 could also sustain the survival of hematopoietic cells with its high expression, while Sema3 gene expression may be inhibited in AML and CML.

Neufeld G, Shraga-Heled N, Lange T, et al.
Semaphorins in cancer.
Front Biosci. 2005; 10:751-60 [PubMed] Related Publications
The semaphorins are the products of a large family of genes currently containing more than 30 members. These genes are divided into eight classes of which classes 1, 2 and 8 contain invertebrate and viral semaphorins, while classes 3-7 contain the vertebrate semaphorins. The semaphorins have been implicated in diverse developmental processes such as axon guidance during nervous system development and regulation of cell migration. Plexin receptors function as binding and signal transducing receptors for all semaphorins except for the class-3 semaphorins which bind to neuropilins which subsequently activate signaling through associated plexins. The class-3 semaphorins semaphorin-3B (s3b) and semaphorin-3F (s3f) function additionally as potent inhibitors of tumor development in small cell lung carcinoma. Recent evidence indicates that these semaphorins modulate the adhesive and migratory properties of responsive malignant cells. S3f as well as semaphorin-3A (s3a) were also found to function as inhibitors of angiogenesis, and it was shown that the anti-angiogenic properties of s3f contribute significantly to its anti-tumorigenic properties. In contrast with these inhibitory semaphorins, there is some evidence indicating that semaphorins such as semaphorin-3C (s3c), semaphorin-3E (s3e), semaphorin-4D (s4d), semaphorin-5C (s5c) semaphorin-6A (s6a) and semaphorin-6b (s6b) may contribute to tumorigenesis or to tumor progression. In this review we discuss the semaphorins, their receptors and their signal transduction mechanisms, and evidence linking semaphorins to the control of tumorigenesis and tumor progression.

Rieger J, Wick W, Weller M
Human malignant glioma cells express semaphorins and their receptors, neuropilins and plexins.
Glia. 2003; 42(4):379-89 [PubMed] Related Publications
Semaphorins comprise a family of molecules implicated in the guiding of growing axons and neuronal progenitor cells. Further, semaphorins have been suggested to play a role in cancer metastasis. Neuropilins 1 and 2 are cell surface receptors for soluble class 3 semaphorins. Plexins are direct receptors for membrane-bound semaphorins and, by binding to neuropilins, coreceptors necessary for class 3 semaphorin signaling. We here report that human malignant glioma cell lines express neuropilins 1 and 2 mRNA and protein, as well as either plexin A1, A2, or B1. Further, all glioma cell lines express SEMA3A and SEMA3C and exhibit SEMA3A binding sites. Exogenous SEMA3A expressed in 293 or U87MG cells has no collapsing or chemorepulsive activities on glioma cells as determined by F-actin staining and collagen coculture assays. In summary, human glioma cells express class 3 semaphorins and receptors for soluble and membrane-bound semaphorins, suggesting a possible role of the semaphorin/neuropilin system in the interactions of human malignant glioma with the host's central nervous and immune systems.

Shih JY, Lee YC, Yang SC, et al.
Collapsin response mediator protein-1: a novel invasion-suppressor gene.
Clin Exp Metastasis. 2003; 20(1):69-76 [PubMed] Related Publications
Numerous genetic changes are associated with metastasis of cancer cells. Previously, we used microarray to identify that collapsin response mediator protein-1 (CRMP-1) was involved in cancer invasion and metastasis. We further characterized that CRMP-1 was a novel invasion-suppression gene. Members of the CRMP gene family are intracellular phosphoproteins involved in the mediation of semaphorin induced F-actin depolymerization and growth cone collapse. The precise mechanism by which CRMP-I inhibits invasion is not yet clear. However, CRMP-1 transfected cells had fewer filopodia and less Matrigel-invasion abilities. A low expression of CRMP-I mRNA in lung cancer tissue was significantly associated with advanced disease, lymph node metastasis, early post-operative relapse, and shorter survival. In this article, we reviewed the functions of CRMPs and semaphorins and analyzed the structure and motifs of CRMP-1 by bioinformatics. As such, we hoped to shed further light on the mechanism by which CRMP-1 suppresses the invasion of cancer cells.

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