Unraveling the Link of Altered TGFß Signaling with Scoliotic Vertebral Malformations in Osteogenesis Imperfecta: A Comprehensive Review.

Osteogenesis Imperfecta (OI) is a genetic disorder caused by mutations in genes responsible for collagen synthesis or polypeptides involved in the formation of collagen fibers. Its predominant skeletal complication is scoliosis, impacting 25 to 80% of OI patients. Vertebral deformities of the scoliotic curves in OI include a variety of malformations such as codfish, wedged-shaped vertebrae or platyspondyly, craniocervical junction abnormalities, and lumbosacral spondylolysis and spondylolisthesis. Although the precise pathophysiology of these spinal deformities remains unclear, anomalies in bone metabolism have been implicated in the progression of scoliotic curves. Bone Mineral Density (BMD) measurements have demonstrated a significant reduction in the Z-score, indicating osteoporosis and a correlation with the advancement of scoliosis. Factors such as increased mechanical strains, joint hypermobility, lower leg length discrepancy, pelvic obliquity, spinal ligament hypermobility, or vertebrae microfractures may also contribute to the severity of scoliosis. Histological vertebral analysis has confirmed that changes in trabecular microarchitecture, associated with inadequate bone turnover, indicate generalized bone metabolic defects in OI. At the molecular level, the upregulation of Transforming Growth factor-ß (TGFß) signaling in OI can lead to disturbed bone turnover and changes in muscle mass and strength. Understanding the relationship between spinal clinical features and molecular pathways could unveil TGFß -related molecular targets, paving the way for novel therapeutic approaches in OI.

Targeting the interaction of pleiotrophin and VEGFA165 with protein tyrosine phosphatase receptor zeta 1 inhibits endothelial cell activation and angiogenesis.

Protein tyrosine phosphatase receptor zeta 1 (PTPRZ1) is a transmembrane tyrosine phosphatase (TP) that serves as a receptor for pleiotrophin (PTN) and vascular endothelial growth factor A 165 (VEGFA165) to regulate endothelial cell migration. In the present work, we identify a PTN peptide fragment (PTN97-110) that inhibits the interaction of PTN and VEGFA165 with PTPRZ1 but not VEGF receptor 2. This peptide abolishes the stimulatory effect of PTN and VEGFA165 on endothelial cell migration, tube formation on Matrigel, and Akt activation in vitro. It also partially inhibits VEGFA165-induced VEGF receptor 2 activation but does not affect ERK1/2 activation and cell proliferation. In vivo, PTN97-110 inhibits or dysregulates angiogenesis in the chick embryo chorioallantoic membrane and the zebrafish assays, respectively. In glioblastoma cells in vitro, PTN97-110 abolishes the stimulatory effect of VEGFA165 on cell migration and inhibits their anchorage-independent growth, suggesting that this peptide might also be exploited in glioblastoma therapy. Finally, in silico and experimental evidence indicates that PTN and VEGFA165 bind to the extracellular fibronectin type-III (FNIII) domain to stimulate cell migration. Collectively, our data highlight novel aspects of the interaction of PTN and VEGFA165 with PTPRZ1, strengthen the notion that PTPRZ1 is required for VEGFA165-induced signaling, and identify a peptide that targets this interaction and can be exploited for the design of novel anti-angiogenic and anti-glioblastoma therapeutic approaches.

Bone mineral density, vitamin D and osseous metabolism indices in neurofibromatosis type 1: A systematic review and meta-analysis.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a genetic autosomal neurocutaneous syndrome correlated with skeletal dysplasia and defects in the osseous microarchitecture. The physiological mechanism for the development of NF1-related bone abnormal turnover is still unclear. OBJECTIVES: A meta-analysis was performed to investigate the effects of NF1 on bone mineral density (BMD) and osseous metabolic indices in order to provide clinical evidence for the pathogenesis of the associated skeletal deformities. METHODS: A systematic literature review search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in the PubMed/Medline and Web of Science databases from the date of inception of each database through to 10 September 2023. Specific inclusion and exclusion criteria were applied for the identification of studies examining the effects of NF1 on bone strength and metabolism. The Newcastle-Ottawa and Jadad scales were applied to assess the quality of the included studies. RevMan 5.3 software was used for the analysis of the data, and MedCalc was applied to examine publication bias. RESULTS: Overall, 13 studies met the inclusion criteria comprised of 5 cross-sectional, 6 case-control and 2 retrospective studies. 703 patients and 973 healthy subjects formed the NF1 and control group, respectively. The results of the meta-analysis displayed that lumbar (SMD = -3.85, 95%CI = -7.53 to -0.18, Z = 2.05, p = 0.04) and femoral (SMD = -4.78, 95%CI = -8.86 to -0.69, Z = 2.29, p = 0.02) BMD was reduced in the NF1 group. Both in children and adults the serum levels of 25 hydroxyvitamin D3 were also decreased in NF1 group, but without any statistical significance (SMD = -0.62, 95%CI = -1.34 to -0.11, Z = 1.66, p = 0.10). Serum Parathyroid hormone (PTH) (SMD = 0.73, 95%CI = 0.31 to 1.15, Z = 3.43, p = 0.0006) and C-telopeptide of type 1 collagen (CTX) (SMD = 0.82, 95%CI = 0.33 to 1.30, Z = 3.29, p = 0.001) were elevated in NF1 patients, while serum calcium (SMD = -0.10, 95%CI = -0.74 to 0.53, Z = 0.32, p = 0.75) phosphorous (SMD = 0.33, 95%CI = -0.38 to 1.05, Z = 0.92, p = 0.36), alkaline phosphatase (ALP) (SMD = -0.36, 95%CI = -0.77 to 0.05, Z = 1.71, p = 0.09), osteocalcin (SMD = 1.81, 95%CI = -0.37 to -3.98, Z = 1.63, p = 0.10) and bone formation markers (SMD = 0.28, 95%CI = -0.37 to -0.94, Z = 0.85, p = 0.39) were not. CONCLUSION: NF1 is associated with decreased BMD at the lumbar spine and femur. Taking into account that the serum levels of PTH, CTX were increased whereas the concentrations of vitamin D, calcium, phosphorous, ALP, osteocalcin and bone formation markers were not altered significantly in the NF1 patients compared with the healthy subjects, a vitamin D independent dysregulated bone cellular activity could be considered. STUDY REGISTRATION: Registered on PROSPERO (CRD42023424751).

Genetic deletion or tyrosine phosphatase inhibition of PTPRZ1 activates c-Met to up-regulate angiogenesis and lung adenocarcinoma growth.

Protein tyrosine phosphatase receptor zeta 1 (PTPRZ1) is a transmembrane tyrosine phosphatase (TP) expressed in endothelial cells and required for stimulation of cell migration by vascular endothelial growth factor A165 (VEGFA165 ) and pleiotrophin (PTN). It is also over or under-expressed in various tumor types. In this study, we used genetically engineered Ptprz1-/- and Ptprz1+/+ mice to study mechanistic aspects of PTPRZ1 involvement in angiogenesis and investigate its role in lung adenocarcinoma (LUAD) growth. Ptprz1-/- lung microvascular endothelial cells (LMVEC) have increased angiogenic features compared with Ptprz1+/+ LMVEC, in line with the increased lung angiogenesis and the enhanced chemically induced LUAD growth in Ptprz1-/- compared with Ptprz1+/+ mice. In LUAD cells isolated from the lungs of urethane-treated mice, PTPRZ1 TP inhibition also enhanced proliferation and migration. Expression of beta 3 (ß3 ) integrin is decreased in Ptprz1-/- LMVEC, linked to enhanced VEGF receptor 2 (VEGFR2), c-Met tyrosine kinase (TK) and Akt kinase activities. However, only c-Met and Akt seem responsible for the enhanced endothelial cell activation in vitro and LUAD growth and angiogenesis in vivo in Ptprz1-/- mice. A selective PTPRZ1 TP inhibitor, VEGFA165 and PTN also activate c-Met and Akt in a PTPRZ1-dependent manner in endothelial cells, and their stimulatory effects are abolished by the c-Met TK inhibitor (TKI) crizotinib. Altogether, our data suggest that low PTPRZ1 expression is linked to worse LUAD prognosis and response to c-Met TKIs and uncover for the first time the role of PTPRZ1 in mediating c-Met activation by VEGFA and PTN.

Protein Tyrosine Phosphatase Receptor Zeta 1 as a Potential Target in Cancer Therapy and Diagnosis.

Protein tyrosine phosphatase receptor zeta 1 (PTPRZ1) is a type V transmembrane tyrosine phosphatase that is highly expressed during embryonic development, while its expression during adulthood is limited. PTPRZ1 is highly detected in the central nervous system, affecting oligodendrocytes' survival and maturation. In gliomas, PTPRZ1 expression is significantly upregulated and is being studied as a potential cancer driver and as a target for therapy. PTPRZ1 expression is also increased in other cancer types, but there are no data on the potential functional significance of this finding. On the other hand, low PTPRZ1 expression seems to be related to a worse prognosis in some cancer types, suggesting that in some cases, it may act as a tumor-suppressor gene. These discrepancies may be due to our limited understanding of PTPRZ1 signaling and tumor microenvironments. In this review, we present evidence on the role of PTPRZ1 in angiogenesis and cancer and discuss the phenomenal differences among the different types of cancer, depending on the regulation of its tyrosine phosphatase activity or ligand binding. Clarifying the involved signaling pathways will lead to its efficient exploitation as a novel therapeutic target or as a biomarker, and the development of proper therapeutic approaches.

Subchondral Bone Cyst Development in Osteoarthritis: From Pathophysiology to Bone Microarchitecture Changes and Clinical Implementations.

Osteoarthritis is a degenerative joint disease affecting middle-aged and elderly patients. It mainly involves weight-bearing joints such as the hip, knee and spine as well as the basilar joint of the thumb, causing dysfunction and painful symptoms. Often, joint arthritis is accompanied by cartilage defects, joint space narrowing, osteophytes, bone sclerosis and subchondral bone cysts (SBC). The aim of the present study was to explore the pathophysiology responsible for the development of SBCs as well as the association between SBCs and disease progress, the level of clinical symptoms and their impact on postoperative outcomes and risk of possible complications following joint replacements if left untreated. A literature review on PubMed articles was conducted to retrieve and evaluate all available evidence related to the main objective mentioned above. A few theories have been put forth to explain the formation process of SBCs. These involve MMPs secretion, angiogenesis, and enhanced bone turnover as a biological response to abnormal mechanical loads causing repeated injuries on cartilage and subchondral tissue during the development of arthritis. However, the application of novel therapeutics, celecoxib-coated microspheres, local administration of IGF-1 and activated chondrocytes following surgical debridement of SBCs hinders the expansion of SBCs and prevents the progression of osteoarthritis.

Doxycycline inhibits the progression of metastases in early-stage osteosarcoma by downregulating the expression of MMPs, VEGF and ezrin at primary sites.

INTRODUCTION: Osteosarcoma (OS) is the most common primary osseous malignant tumour, with high propensity to metastasise in lungs. Pulmonary micro-metastases are present in up to 80% of patients at initial diagnosis and they are associated with significantly worse prognosis. Doxycycline (Dox) is a synthetic tetracycline that has been shown to have anti-cancer properties in vitro and in vivo, and inhibit angiogenesis - effects that may prove beneficial for several types of cancer. The aim of the present work was to study how Dox affects OS cell growth in vitro and in vivo and OS-driven pulmonary metastasis in vivo. METHODS: In vitro, the effect of Dox was measured in MG-63 and 143B human OS cell viability, apoptosis, invasion and migration. In vivo, highly metastatic 143B cells were orthotopically implanted into the tibia of SCID mice. The tumour growth and pulmonary metastases between Dox treated and untreated, non-amputated and early amputated xenografts were examined. RESULTS: In vitro, Dox decreased viability, inhibited invasion, migration, and induced the apoptosis of OS cells. In vivo, Dox significantly enhanced tumour necrosis at primary OS sites, similarly to its in vitro effect, and downregulated the expression of Ki67, MMP2, MMP9, VEGFA and ezrin. It also decreased circulating VEGFA and MMP9 protein levels, in line with the decreased metastatic burden in Dox-treated mice (non-amputated and early-amputated). CONCLUSIONS: Reprofiling of Dox can prevent the evolvement of pulmonary micro-metastases to clinically detectable macro-metastases and suppress the lethal progress of OS by inhibiting the expression of MMPs, VEGFA and ezrin at primary sites.

Binding of pleiotrophin to cell surface nucleolin mediates prostate cancer cell adhesion to osteoblasts.

Pleiotrophin (PTN) is a growth factor that appears to play an important role in prostate cancer growth and angiogenesis. We have previously shown that decreased PTN expression in human prostate cancer PC3 cells leads to decreased adhesion of prostate cancer cells to osteoblasts, suggesting that PTN mediates this interaction. In the current work, using peptides that correspond to different regions of the PTN protein, we identified that a domain responsible for the adhesion of prostate cancer cells to osteoblasts corresponds to amino acids 16-24 of the mature PTN protein. Given that a synthetic PTN16-24 peptide which disturbs the interaction of PTN with nucleolin (NCL) was found to inhibit prostate cancer cells' adhesion to osteoblasts, it seems that NCL mediates the cellular interactions involved in the adhesion process. Two pseudopeptides that bind to cell surface NCL and an anti-NCL antibody also decrease prostate cancer cell adhesion to osteoblasts to the same degree as PTN16-24, further supporting the involvement of cell surface NCL in this interaction. Collectively, our data suggest that NCL on the cell surface of osteoblasts may mediate adhesion of prostate cancer cells through PTN and identify peptides that could be exploited therapeutically to target this component of prostate cancer bone metastases.

Current Aspects on the Pathophysiology of Bone Metabolic Defects during Progression of Scoliosis in Neurofibromatosis Type 1.

Neurofibromatosis type 1 (NF1), which is the most common phacomatoses, is an autosomal dominant disorder characterized by clinical presentations in various tissues and organs, such as the skin, eyes and nervous and skeletal systems. The musculoskeletal implications of NF1 include a variety of deformities, including scoliosis, kyphoscoliosis, spondylolistheses, congenital bony bowing, pseudarthrosis and bone dysplasia. Scoliosis is the most common skeletal problem, affecting 10-30% of NF1 patients. Although the pathophysiology of spinal deformities has not been elucidated yet, defects in bone metabolism have been implicated in the progression of scoliotic curves. Measurements of Bone Mineral Density (BMD) in the lumbar spine by using dual energy absorptiometry (DXA) and quantitative computer tomography (QCT) have demonstrated a marked reduction in Z-score and osteoporosis. Additionally, serum bone metabolic markers, such as vitamin D, calcium, phosphorus, osteocalcin and alkaline phosphatase, have been found to be abnormal. Intraoperative and histological vertebral analysis confirmed that alterations of the trabecular microarchitecture are associated with inadequate bone turnover, indicating generalized bone metabolic defects. At the molecular level, loss of function of neurofibromin dysregulates Ras and Transforming Growth factor-ß1 (TGF-ß1) signaling and leads to altered osteoclastic proliferation, osteoblastic activity and collagen production. Correlation between clinical characteristics and molecular pathways may provide targets for novel therapeutic approaches in NF1.

On the role of pleiotrophin and its receptors in development and angiogenesis.

The secreted growth factor pleiotrophin (PTN) is expressed in all species and is evolutionarily highly conserved, suggesting that it plays a significant role in the regulation of important processes. The observation that it is highly expressed at early stages during development and in embryonic progenitor cells highlights a potentially important contribution to development. There is ample evidence of the role of PTN in the development of the nervous system and hematopoiesis, some, albeit inconclusive, evidence of its role in the skeletomuscular system, and limited evidence of its role in the development of other organs. Studies on its role in the cardiovascular system and angiogenesis suggest that PTN has a significant regulatory effect by acting on endothelial cells, while its role in the functions of smooth or cardiac muscle cells has not been studied. This review highlights what is known to date regarding the role of PTN in the development of various organs and in angiogenesis. Wherever possible, evidence on the crosstalk between the receptors that mediate PTN's functions is also quoted, highlighting the complex regulatory pathways that affect development and angiogenesis.

Protein tyrosine phosphatase receptor-ζ1 deletion triggers defective heart morphogenesis in mice and zebrafish.

Protein tyrosine phosphatase receptor-ζ1 (PTPRZ1) is a transmembrane tyrosine phosphatase receptor highly expressed in embryonic stem cells. In the present work, gene expression analyses of Ptprz1-/- and Ptprz1+/+ mice endothelial cells and hearts pointed to an unidentified role of PTPRZ1 in heart development through the regulation of heart-specific transcription factor genes. Echocardiography analysis in mice identified that both systolic and diastolic functions are affected in Ptprz1-/- compared with Ptprz1+/+ hearts, based on a dilated left ventricular (LV) cavity, decreased ejection fraction and fraction shortening, and increased angiogenesis in Ptprz1-/- hearts, with no signs of cardiac hypertrophy. A zebrafish ptprz1-/- knockout was also generated and exhibited misregulated expression of developmental cardiac markers, bradycardia, and defective heart morphogenesis characterized by enlarged ventricles and defected contractility. A selective PTPRZ1 tyrosine phosphatase inhibitor affected zebrafish heart development and function in a way like what is observed in the ptprz1-/- zebrafish. The same inhibitor had no effect in the function of the adult zebrafish heart, suggesting that PTPRZ1 is not important for the adult heart function, in line with data from the human cell atlas showing very low to negligible PTPRZ1 expression in the adult human heart. However, in line with the animal models, Ptprz1 was expressed in many different cell types in the human fetal heart, such as valvar, fibroblast-like, cardiomyocytes, and endothelial cells. Collectively, these data suggest that PTPRZ1 regulates cardiac morphogenesis in a way that subsequently affects heart function and warrant further studies for the involvement of PTPRZ1 in idiopathic congenital cardiac pathologies.NEW & NOTEWORTHY Protein tyrosine phosphatase receptor ζ1 (PTPRZ1) is expressed in fetal but not adult heart and seems to affect heart development. In both mouse and zebrafish animal models, loss of PTPRZ1 results in dilated left ventricle cavity, decreased ejection fraction, and fraction shortening, with no signs of cardiac hypertrophy. PTPRZ1 also seems to be involved in atrioventricular canal specification, outflow tract morphogenesis, and heart angiogenesis. These results suggest that PTPRZ1 plays a role in heart development and support the hypothesis that it may be involved in congenital cardiac pathologies.

Pleiotrophin selectively binds to vascular endothelial growth factor receptor 2 and inhibits or stimulates cell migration depending on ανß3 integrin expression.

Pleiotrophin (PTN) has a moderate stimulatory effect on endothelial cell migration through ανß3 integrin, while it decreases the stimulatory effect of vascular endothelial growth factor A (VEGFA) and inhibits cell migration in the absence of ανß3 through unknown mechanism(s). In the present work, by using a multitude of experimental approaches, we show that PTN binds to VEGF receptor type 2 (VEGFR2) with a KD of 11.6 nM. Molecular dynamics approach suggests that PTN binds to the same VEGFR2 region with VEGFA through its N-terminal domain. PTN inhibits phosphorylation of VEGFR2 at Tyr1175 and still stimulates endothelial cell migration in the presence of a selective VEGFR2 tyrosine kinase inhibitor. VEGFR2 downregulation by siRNA or an anti-VEGFR2 antibody that binds to the ligand-binding VEGFR2 domain also induce endothelial cell migration, which is abolished by a function-blocking antibody against ανß3 or the peptide PTN112-136 that binds ανß3 and inhibits PTN binding. In cells that do not express ανß3, PTN decreases both VEGFR2 Tyr1175 phosphorylation and cell migration in a VEGFR2-dependent manner. Collectively, our data identify VEGFR2 as a novel PTN receptor involved in the regulation of cell migration by PTN and contribute to the elucidation of the mechanism of activation of endothelial cell migration through the interplay between VEGFR2 and ανß3.

Assessment and Optimization of the Pediatric Parenteral Nutrition Preparation Process in a Hospital Pharmacy.

BACKGROUND: Parenteral nutrition (PN) is associated with risks that could threaten the clinical condition of premature neonates hospitalized in the neonatal intensive care unit. In this work, risk-analysis methodology was implemented to contain the risks associated with the PN production process and improve PN safety. METHODS: The Failure Modes, Effects, and Criticality Analysis was performed by a multidisciplinary team. All potential failure modes of the PN preparation process were recorded, and associated risks were scored based on their severity, occurrence, and detectability, with a risk priority number (RPN). All identified failure scenarios and the respective work stages were ranked in descending order of criticality. Corrective actions were proposed to address critical points, and the safety of the process was reassessed by the same method in a prospective manner. RESULTS: The highest RPN scores were obtained with the PN composition calculation performed manually (RPN: 530) or electronically (RPN: 478), completion of the PN medical order form (RPN: 354), manual compounding of PN admixtures (RPN: 258), and the structure/organization/maintenance of the PN preparation unit (RPN: 133). The quality and safety of PN admixtures could be compromised by many critical factors, such as the increased particle-microbial load in the unit and the inadequate training/experience of the involved health professionals and their incompliance with the given instructions. The implementation of the proposed corrective measures is expected to reduce the risks of the overall PN production process by 67.5%. CONCLUSIONS: Improvement of the PN production process through risk-analysis methodologies enhances safety for premature neonates.

Vaccinations in Infants Born Preterm: An Update.

Infants born prematurely (before completion of 37 weeks of gestation) are at increased risk of morbidity and mortality due to vaccine preventable diseases, mostly because of their immunological immaturity and failure of transfer of maternal protective antibodies. Despite their great need of being vaccinated, concerns on vaccine safety and efficacy, constitute the main reasons for which vaccinations are often delayed in this group. In this review we summarize the latest evidence on vaccine safety, efficacy and immunogenicity in preterm infants which is similar to full-term infants. Therefore there is no reason for delaying vaccination in this population.

Improvement of Chemotherapy Solutions Production Procedure in a Hospital Central Chemotherapy Preparation Unit: A Systematic Risk Assessment to Prevent Avoidable Harm in Cancer Patients.

OBJECTIVE: This study was designed to reevaluate and improve the quality and safety of the chemotherapy preparation in a Central Chemotherapy Preparation Unit of a Public Hospital. METHODS: A failure modes, effects, and criticality analysis (FMECA) was conducted by a multidisciplinary team. All potential failure modes at each stage of the chemotherapy preparation were recorded, and the associated risks were scored for their severity, occurrence, and detectability with a risk priority number (RPN). Corrective actions were suggested, and new RPNs were estimated for the modified process. RESULTS: Failure modes, effects, and criticality analysis and priority matrix construction, revealed that the partial compliance of Unit's premises with international standards (RPNstage: 307), the human errors throughout the compounding (RPNstage: 223)-labeling (RPNstage: 216)-prescribing (RPNstage: 198) steps, and the violation of working protocols by employees (RPNstage: 215), were the most important risks for which either urgent or immediate corrective actions had to be taken. Modifying the procedure through the proposed corrective actions is expected to lead to a significant (71.3%) risk containment, with a total RPNpreparation process reduction from 2102 to 604. CONCLUSIONS: Failure modes, effects, and criticality analysis and priority matrix development identified and prioritized effectively the risks associated with chemotherapy preparation allowing for the improvement of health services to cancer patients.

Insight into the role of chondroitin sulfate E in angiogenesis.

Chondroitin sulfate E (CS-E) is a glycosaminoglycan containing type-E disaccharide units (sulfated at C-4 and C-6 of N-acetylgalactosamine). CS-E is covalently linked to a core protein to form chondroitin sulfate proteoglycans (PGs) that are secreted or associated with the plasma membrane of several types of cells. CS-E-containing PGs selectively interact with growth factors and chemokines and control various cellular and/or tissue processes. Angiogenesis is a process that is highly regulated in physiological conditions but deregulated in pathologies, leading to excess or deficient blood vessel formation. Angiogenesis regulation is orchestrated by numerous growth factors, such as vascular endothelial growth factor A, fibroblast growth factors and pleiotrophin, whose functions can be affected by CS-containing PGs. In the present review, we focus on the emerging area of CS-mediated angiogenesis and particularly on the critical assessment of data related to a potential role of CS-E in controlling endothelial cell functions, focusing on angiogenesis regulation and vascular homeostasis in health and disease.

In Vitro Spheroid Sprouting Assay of Angiogenesis.

Angiogenesis is a well-coordinated physiological process that leads to new blood vessel formation. Physiologically, angiogenesis is more prominent during development and wound healing and its dysregulation drives or is related to several diseases, including cancer. The endothelial cells are the main regulators of the angiogenic process, and thus the angiogenic outcome is assessed based on the effect on endothelial cell functions. Several in vitro and in vivo techniques have been developed to assess the effect of various factors on angiogenesis. Compared to the in vivo techniques, the in vitro techniques are considered less physiologically relevant. This has been partially overcome by the development of 3-dimensional (3D) in vitro models, one of which is the spheroid assay or 3D sprouting assay that exploits the effect of the extracellular matrix to endothelial cell functions. This chapter focuses on the description of the spheroid assay and mentions the variations and potential applications this assay can have.

Matrigel Plug Assay for In Vivo Evaluation of Angiogenesis.

Matrigel is extracted from the Engelbreth-Holm-Swarm (EHS) mouse sarcoma in C57BL/6 mice, a tumor rich in extracellular matrix (ECM) proteins. It consists mainly of laminin (approximately 60%), collagen IV (approximately 30%), and nidogen-1/entactin (approximately 8%), while it also contains heparan sulfate proteoglycans, such as perlecan, other ECM proteins, as well as growth factors bound to the ECM. Matrigel mimics the physiological cell matrix and is the most commonly used matrix substrate to study in vitro and in vivo angiogenesis. Here, we describe the in vivo Matrigel plug assay and how it can be used for both qualitative and quantitative assessment of angiogenesis.

Cyclin-dependent kinase 5 mediates pleiotrophin-induced endothelial cell migration.

Pleiotrophin (PTN) stimulates endothelial cell migration through binding to receptor protein tyrosine phosphatase beta/zeta (RPTPß/ζ) and ανß3 integrin. Screening for proteins that interact with RPTPß/ζ and potentially regulate PTN signaling, through mass spectrometry analysis, identified cyclin-dependent kinase 5 (CDK5) activator p35 among the proteins displaying high sequence coverage. Interaction of p35 with the serine/threonine kinase CDK5 leads to CDK5 activation, known to be implicated in cell migration. Protein immunoprecipitation and proximity ligation assays verified p35-RPTPß/ζ interaction and revealed the molecular association of CDK5 and RPTPß/ζ. In endothelial cells, PTN activates CDK5 in an RPTPß/ζ- and phosphoinositide 3-kinase (PI3K)-dependent manner. On the other hand, c-Src, ανß3 and ERK1/2 do not mediate the PTN-induced CDK5 activation. Pharmacological and genetic inhibition of CDK5 abolished PTN-induced endothelial cell migration, suggesting that CDK5 mediates PTN stimulatory effect. A new pyrrolo[2,3-α]carbazole derivative previously identified as a CDK1 inhibitor, was found to suppress CDK5 activity and eliminate PTN stimulatory effect on cell migration, warranting its further evaluation as a new CDK5 inhibitor. Collectively, our data reveal that CDK5 is activated by PTN, in an RPTPß/ζ-dependent manner, regulates PTN-induced cell migration and is an attractive target for the inhibition of PTN pro-angiogenic properties.

Anaplastic Lymphoma Kinase in Glioblastoma: Detection/Diagnostic Methods and Therapeutic Options.

BACKGROUND: Glioblastoma (GBM) is the most aggressive and common brain tumor in adults, currently lacking effective life-prolonging and recurrence-preventing therapy; median survival of GBM patients stands at only 14-16 months. Increasing lines of evidence indicate that Anaplastic lymphoma kinase (ALK), a druggable tyrosine kinase receptor over-expressed in GBM, represents a potential therapeutic target in this tumor. OBJECTIVE: An overview of the state of the art and the existing recent patents regarding potential exploitation of ALK as a therapeutic target and/or diagnostic/prognostic factor in GBM. METHOD: Recent literature and patents focusing on or including ALK pre-clinical and clinical research in GBM have been identified and reviewed, and are discussed according to their potential use. RESULTS: Numerous recent ALK-related patents were identified. They were reviewed/analyzed in relation to previously published research and categorized based on their potential in GBM: i) diagnosis/ prognosis, ii) drug-based therapeutic targeting of ALK using a single compound or combination schemes and iii) therapeutic ALK targeting by other means, e.g. ALK vaccination. CONCLUSION: ALK targeting holds promise as a novel therapeutic approach in GBM, especially in combination schemes allowing multi-target therapy. Such schemes may incorporate detection-guided therapy and utilize next generation inhibitory compounds with improved central nervous system penetration. Moreover, identification of ALK-mediated molecular pathway(s) related to GBM carcinogenesis/ pathology and putative therapy resistance is of high priority and warrants further exploitation.