Pleiotrophin, a multifunctional tumor promoter through induction of tumor angiogenesis, remodeling of the tumor microenvironment, and activation of stromal fibroblasts

Clinicopathological diagnosis of morphea-like carcinoma en cuirasse in the neck: a rare presentation of lung cancer

BACKGROUND

Carcinoma en cuirasse is mostly reported in breast cancer. It rarely originates from other visceral tumors such as lung cancer. In this report, we highlight the importance of skin biopsy not to make a misdiagnosis or missed diagnosis.

CASE PRESENTATION

We report a 51-year-old male, diagnosed with lung adenocarcinoma 2 years ago, presenting as swelling and hardening of the face and neck. The patient was diagnosed with carcinoma en cuirasse from lung cancer and was transferred to the oncology department for further management. Unfortunately, the patient gave up treatment after 3 months and died after 1 year of follow-up.

CONCLUSION

In patients with tumors that present as swelling and hardening of the skin, the possibility of skin metastases should be considered, and the necessity of early skin biopsy should be taken into account.

Integrated multi-omics analysis describes immune profiles in ischemic heart failure and identifies PTN as a novel biomarker

Introduction

Heart failure is a leading global cause of mortality, with ischemic heart failure (IHF) being a major contributor. IHF is primarily driven by coronary artery disease, and its underlying mechanisms are not fully understood, particularly the role of immune responses and inflammation in cardiac muscle remodeling. This study aims to elucidate the immune landscape of heart failure using multi-omics data to identify biomarkers for preventing cardiac fibrosis and disease progression.

Methods

We utilized multi-omics data to elucidate the intricate immune landscape of heart failure at various regulatory levels. Given the substantial size of our transcriptomic dataset, we used diverse machine learning techniques to identify key mRNAs. For smaller datasets such as our proteomic dataset, we applied multilevel data cleansing and enhancement using principles from network biology. This comprehensive analysis led to the development of a scalable, integrated -omics analysis pipeline.

Results

Pleiotrophin (PTN) had shown significant upregulation in multiple datasets and the activation of various molecules associated with dysplastic cardiac remodeling. By synthesizing these data with experimental validations, PTN was identified as a potential biomarker.

Discussion

The present study not only provides a comprehensive perspective on immune dynamics in IHF but also offers valuable insights for the identification of biomarkers, discovery of therapeutic targets, and development of drugs.

Carcinoma en cuirasse in a middle-aged woman with a unique spoke-wheel presentation: A case report

Carcinoma en cuirasse is a rare form of cutaneous metastasis characterized by the spread of a primary malignant tumor to the skin, most commonly associated with breast cancer in women. It may present as papulonodular lesions, erysipeloid, sclerodermiform infiltration, or en cuirassed, typically appearing months or years after the initial diagnosis of the primary malignancy. Diagnosis of carcinoma en cuirasse can be challenging, but histology can help distinguish it from other skin conditions. Treatment options for carcinoma en cuirasse are not well-defined due to the limited number of reported cases. Here, we report a case of a 30-year-old female, who presented with invasive ductal carcinoma which presented as carcinoma en cuirasse with a spoke-wheel pattern over the course of 6 months.

Carcinoma en Cuirasse as the heralding sign of underlying HER-2 positive male breast cancer

Carcinoma en cuirasse (CeC) is an uncommon presentation of metastatic cutaneous carcinoma, most often originating from breast carcinoma. We present a case study of a man in his 30s exhibiting progressive skin thickening over the left chest, alongside appetite and weight loss. On examination, the patient had painless skin induration and palpable, matted, hard, immobile and non-tender axillary, cervical and inguinal lymphadenopathy. Imaging revealed metabolically active left cervical, retro pectoral, inguinal and bilateral axillary lymph nodes with muscle involvement, likely neoplastic. Histopathology demonstrated metastatic carcinoma, morphologically originating from the breast. CeC most often presents after therapy, but our case reveals that it may be a presenting sign of an occult malignancy. CeC should be differentiated from non-oncological causes of skin thickening. Detailed history, physical examination and appropriate radiological investigations are essential. Although rare in young individuals, neoplastic aetiology should be considered if the history and physical examination suggest it.

Multi-omics analysis reveals cuproptosis and mitochondria-based signature for assessing prognosis and immune landscape in osteosarcoma

Background

Osteosarcoma (OSA), the most common primary mesenchymal bone tumor, is a health threat to children and adolescents with a dismal prognosis. While cuproptosis and mitochondria dysfunction have been demonstrated to exert a crucial role in tumor progression and development, the mechanisms by which they are regulated in OSA still await clarification.

Methods

Two independent OSA cohorts containing transcriptome data and clinical information were collected from public databases. The heterogeneity of OSA were evaluated by single cell RNA (scRNA) analysis. To identify a newly molecular subtype, unsupervised consensus clustering was conducted. Cox relevant regression methods were utilized to establish a prognostic gene signature. Wet lab experiments were performed to confirm the effect of model gene in OSA cells.

Results

We determined 30 distinct cell clusters and assessed OSA heterogeneity and stemness scRNA analysis. Then, univariate Cox analysis identified 24 candidate genes which were greatly associated with the prognosis of OSA. Based on these prognostic genes, we obtained two molecular subgroups. After conducting step Cox regression, three model genes were selected to construct a signature showing a favorable performance to forecast clinical outcome. Our proposed signature could also evaluate the response to chemotherapy and immunotherapy of OSA cases.

Conclusion

We generated a novel risk model based on cuproptosis and mitochondria-related genes in OSA with powerful predictive ability in prognosis and immune landscape.

Single-cell analysis reveals specific neuronal transition during mouse corticogenesis

Background: Currently, the mechanism(s) underlying corticogenesis is still under characterization. Methods: We curated the most comprehensive single-cell RNA-seq (scRNA-seq) datasets from mouse and human fetal cortexes for data analysis and confirmed the findings with co-immunostaining experiments. Results: By analyzing the developmental trajectories with scRNA-seq datasets in mice, we identified a specific developmental sub-path contributed by a cell-population expressing both deep- and upper-layer neurons (DLNs and ULNs) specific markers, which occurred on E13.5 but was absent in adults. In this cell-population, the percentages of cells expressing DLN and ULN markers decreased and increased, respectively, during the development suggesting direct neuronal transition (namely D-T-U). Whilst genes significantly highly/uniquely expressed in D-T-U cell population were significantly enriched in PTN/MDK signaling pathways related to cell migration. Both findings were further confirmed by co-immunostaining with DLNs, ULNs and D-T-U specific markers across different timepoints. Furthermore, six genes (co-expressed with D-T-U specific markers in mice) showing a potential opposite temporal expression between human and mouse during fetal cortical development were associated with neuronal migration and cognitive functions. In adult prefrontal cortexes (PFC), D-T-U specific genes were expressed in neurons from different layers between humans and mice. Conclusion: Our study characterizes a specific cell population D-T-U showing direct DLNs to ULNs neuronal transition and migration during fetal cortical development in mice. It is potentially associated with the difference of cortical development in humans and mice.

Whole transcriptome analysis of canine pheochromocytoma and paraganglioma

Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors arising from the chromaffin cells in the adrenal medulla and extra-adrenal paraganglia, respectively. Local invasion, concurrent disorders, and metastases prevent surgical removal, which is the most effective treatment to date. Given the current lack of effective medical treatment, there is a need for novel therapeutic strategies. To identify druggable pathways driving PPGL development, we performed RNA sequencing on PPGLs (n = 19) and normal adrenal medullas (NAMs; n = 10) of dogs. Principal component analysis (PCA) revealed that PPGLs clearly clustered apart from NAMs. In total, 4,218 genes were differentially expressed between PPGLs and NAMs. Of these, 232 had a log2 fold change of >3 or < -3, of which 149 were upregulated in PPGLs, and 83 were downregulated. Compared with NAMs, PPGLs had increased expression of genes related to the cell cycle, tumor development, progression and metastasis, hypoxia and angiogenesis, and the Wnt signaling pathway, and decreased expression of genes related to adrenal steroidogenesis. Our data revealed several overexpressed genes that could provide targets for novel therapeutics, such as Ret Proto-Oncogene (RET), Dopamine Receptor D2 (DRD2), and Secreted Frizzled Related Protein 2 (SFRP2). Based on the PCA, PPGLs were classified into 2 groups, of which group 1 had significantly higher Ki67 scores (p = 0.035) and shorter survival times (p = 0.04) than group 2. Increased expression of 1 of the differentially expressed genes between group 1 and 2, pleiotrophin (PTN), appeared to correlate with a more aggressive tumor phenotype. This study has shed light on the transcriptomic profile of canine PPGL, yielding new insights into the pathogenesis of these tumors in dogs, and revealed potential novel targets for therapy. In addition, we identified 2 transcriptionally distinct groups of PPGLs that had significantly different survival times.

Pleiotrophin and the Expression of Its Receptors during Development of the Human Cerebellar Cortex

During embryonic and fetal development, the cerebellum undergoes several histological changes that require a specific microenvironment. Pleiotrophin (PTN) has been related to cerebral and cerebellar cortex ontogenesis in different species. PTN signaling includes PTPRZ1, ALK, and NRP-1 receptors, which are implicated in cell differentiation, migration, and proliferation. However, its involvement in human cerebellar development has not been described so far. Therefore, we investigated whether PTN and its receptors were expressed in the human cerebellar cortex during fetal and early neonatal development. The expression profile of PTN and its receptors was analyzed using an immunohistochemical method. PTN, PTPRZ1, and NRP-1 were expressed from week 17 to the postnatal stage, with variable expression among granule cell precursors, glial cells, and Purkinje cells. ALK was only expressed during week 31. These results suggest that, in the fetal and neonatal human cerebellum, PTN is involved in cell communication through granule cell precursors, Bergmann glia, and Purkinje cells via PTPRZ1, NRP-1, and ALK signaling. This communication could be involved in cell proliferation and cellular migration. Overall, the present study represents the first characterization of PTN, PTPRZ1, ALK, and NRP-1 expression in human tissues, suggesting their involvement in cerebellar cortex development.

Carcinoma En Cuirasse: A Rare but Striking Cutaneous Manifestation of Metastatic Breast Cancer

Carcinoma en cuirasse is a rare cutaneous metastatic presentation of breast cancer with a poor prognosis. We report a female in her 70s with a prior history of left breast ductal carcinoma in situ status post-radiation and lumpectomy who presented with skin thickening of the left breast and a few solid masses in bilateral breasts. Biopsy showed invasive ductal carcinoma of the left breast (estrogen receptor [ER]/progesterone receptor positive [PR], human epidermal growth factor receptor-2 [HER2] negative) and ductal carcinoma in situ of the right breast (ER/PR positive). She underwent a right breast lumpectomy; however, the left breast mastectomy was aborted due to the worsening of her skin findings on preoperative examination. A skin biopsy revealed poorly differentiated invasive ductal carcinoma. She was diagnosed with stage 4 breast cancer, specifically carcinoma en cuirasse. Systemic treatment was initiated, followed by a left breast mastectomy. A surgical biopsy was HER2-positive, and therefore anti-HER2 therapy was given. She remains on maintenance therapy with an excellent response at present.Any unexplained skin findings in breast cancer patients should prompt consideration of carcinoma en cuirasse. With ongoing treatment advances, many newer therapy options are available for metastatic breast cancer. Based on our case, we think that patients with this disease can have better outcomes.

Single-cell RNA sequencing reveals the mediatory role of cancer-associated fibroblast PTN in hepatitis B virus cirrhosis-HCC progression

BACKGROUND

Cancer-associated fibroblasts (CAFs) are essential stromal components in the tumor microenvironment of hepatocellular carcinoma (HCC). Hepatitis B virus (HBV) infection induces pathological changes such as liver fibrosis/cirrhosis and HCC. The aim of this research was to explore the novel mediators of CAFs to modulate HBV cirrhosis-HCC progression.

METHODS

The single-cell transcriptome data of HCC were divided into subsets, and the significant subset related to fibrotic cells, along with biological function, and clinical information of HCC was revealed by integrated data analyses. The cell communication, cells communicated weight analysis of signaling pathways, and key genes in signaling pathways analysis of significant CAFs subclasses were conducted to discover the novel gene of CAFs. Bioinformatics, vitro and HBV transfection assays were used to verify the novel gene is an important target for promoting the progression HBV cirrhosis-HCC progression.

RESULTS

Fibroblasts derived from HCC single-cell data could be separated into three cell subclasses (CAF0-2), of which CAF2 was associated with the HCC clinical information. Fibroblasts have opposite developmental trajectories to immune B cells and CD8 + T cells. CAF0-2 had strong interaction with B cells and CD8 + T cells, especially CAF2 had the highest interaction frequency and weight with B cells and CD8 + T cells. Moreover, PTN participated in CAF2-related pathways involved in the regulation of cell communication, and the interactions among CAF2 and PTN contributed the most to B cells and CD8 + T cells. Furthermore, the genes of PTN, SDC1, and NCL from PTN signaling were highest expression in CAF2, B cells, and CD8 + T cells, respectively, and the interaction of PTN- SDC1 and PTN- NCL contributed most to the interaction of CAF2- B cells and CAF2-CD8 + T cells. Bioinformatics and vitro experiments confirm PTN was upregulated in HCC and promoted the proliferation of tumor cells, and HBV infection could initiate PTN to perform cirrhosis-HCC progression.

CONCLUSION

Our findings revealed CAF was associated with hepatocarcinogenesis, and the functional importance of B cells and CD8 + T cells in modulating CAF in HCC. Importantly, PTN maybe a novel mediator of CAF to mediate HBV cirrhosis-HCC progression.

Wound healing in aged skin exhibits systems-level alterations in cellular composition and cell-cell communication

Delayed and often impaired wound healing in the elderly presents major medical and socioeconomic challenges. A comprehensive understanding of the cellular/molecular changes that shape complex cell-cell communications in aged skin wounds is lacking. Here, we use single-cell RNA sequencing to define the epithelial, fibroblast, immune cell types, and encompassing heterogeneities in young and aged skin during homeostasis and identify major changes in cell compositions, kinetics, and molecular profiles during wound healing. Our comparative study uncovers a more pronounced inflammatory phenotype in aged skin wounds, featuring neutrophil persistence and higher abundance of an inflammatory/glycolytic Arg1^Hi macrophage subset that is more likely to signal to fibroblasts via interleukin (IL)-1 than in young counterparts. We predict systems-level differences in the number, strength, route, and signaling mediators of putative cell-cell communications in young and aged skin wounds. Our study exposes numerous cellular/molecular targets for functional interrogation and provides a hypothesis-generating resource for future wound healing studies.

Neurovascular dysfunction in GRN-associated frontotemporal dementia identified by single-nucleus RNA sequencing of human cerebral cortex

Frontotemporal dementia (FTD) is the second most prevalent form of early-onset dementia, affecting predominantly frontal and temporal cerebral lobes. Heterozygous mutations in the progranulin gene (GRN) cause autosomal-dominant FTD (FTD-GRN), associated with TDP-43 inclusions, neuronal loss, axonal degeneration and gliosis, but FTD-GRN pathogenesis is largely unresolved. Here we report single-nucleus RNA sequencing of microglia, astrocytes and the neurovasculature from frontal, temporal and occipital cortical tissue from control and FTD-GRN brains. We show that fibroblast and mesenchymal cell numbers were enriched in FTD-GRN, and we identified disease-associated subtypes of astrocytes and endothelial cells. Expression of gene modules associated with blood-brain barrier (BBB) dysfunction was significantly enriched in FTD-GRN endothelial cells. The vasculature supportive function and capillary coverage by pericytes was reduced in FTD-GRN tissue, with increased and hypertrophic vascularization and an enrichment of perivascular T cells. Our results indicate a perturbed BBB and suggest that the neurovascular unit is severely affected in FTD-GRN.

The role of menin in bone pathology

Multiple endocrine neoplasia type 1 (MEN1) is the most common cause of hereditary primary hyperparathyroidism (PHPT). Bone disorders are considered one of the key symptoms in PHPT present with the significant reduction in bone mineral density and low-energy fractures. Previously, these bone disorders were believed to be caused solely by the increase in the level of parathyroid hormone and its subsequent effect on bone resorption. The current paradigm, however, states that the mutations in the menin gene, which cause the development of MEN1, can also affect the metabolism of the cells of the osteoid lineage. This review analyzes both the proven and the potential intracellular mechanisms through which menin can affect bone metabolism.

The link between menin and pleiotrophin in the tumor biology of pancreatic neuroendocrine neoplasms

MEN1, which encodes menin protein, is the most frequently mutated gene in pancreatic neuroendocrine neoplasms (pNEN). Pleiotrophin (PTN) was reported being a downstream factor of menin and to promote metastasis in different tumor entities. In this study, the effect of menin and its link to PTN were assessed on features of pNEN cells and outcome of pNEN patients. The expression of menin and PTN in pNEN patient tissues were examined by qRT-PCR and western blot and compared to their metastasis status. Functional assays, including transwell migration/invasion and scratch wound healing assays, were performed on specifically designed CRISPR/Cas9-mediated MEN1-knockout (MEN1-KO) pNEN cell lines (BON1^MEN1-KO and QGP1^MEN1-KO ) to study the metastasis of pNEN. Among 30 menin negative pNEN patients, 21 revealed a strong protein expression of PTN. This combination was associated with metastasis and shorter disease-free survival. Accordingly, in BON1^MEN1-KO and QGP1^MEN1-KO cells, PTN protein expression was positively associated with enhanced cell migration and invasion, which could be reversed by PTN silencing. PTN is a predicting factor of metastatic behavior of menin-deficient-pNEN. In vitro, menin is able to both promote and suppress the metastasis of pNEN by regulating PTN expression depending on the tumoral origin of pNEN cells.

Identification of Hub Diagnostic Biomarkers and Candidate Therapeutic Drugs in Heart Failure

Purpose

The objective of this study was to identify the potential regulatory mechanisms, diagnostic biomarkers, and therapeutic drugs for heart failure (HF).

Methods

Differentially expressed genes (DEGs) between HF and non-failing donors were screened from the GSE57345, GSE5406, and GSE3586 datasets. Database for Annotation Visualization and Integrated Discovery and Metascape were used for Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses respectively. The GSE57345 dataset was used for weighted gene co-expression network analysis (WGCNA). The intersecting hub genes from the DEGs and WGCNA were identified and verified with the GSE5406 and GSE3586 datasets. The diagnostic value of the hub genes was calculated through receiver operating characteristic analysis and net reclassification index (NRI). Gene set enrichment analysis (GSEA) was used to filter out the signaling pathways associated with the hub genes. SYBYL 2.1 was used for molecular docking of hub targets and potential HF drugs obtained from the connection map.

Results

Functional annotation of the DEGs showed enrichment of negative regulation of angiogenesis, endoplasmic reticulum stress response, and heart development. PTN, LUM, ISLR, and ASPN were identified as the hub genes of HF. GSEA showed that the key genes were related to the transforming growth factor-β (TGF-β) and Wnt signaling pathways. Sirolimus, LY-294002, and wortmannin have been confirmed as potential drugs for HF.

Conclusion

We identified new hub genes and candidate therapeutic drugs for HF, which are potential diagnostic, therapeutic and prognostic targets and warrant further investigation.

Primary breast carcinoma en cuirasse. A rare presentation of an aggressive malignancy and review of the literature

Breast carcinoma en cuirasse is a very rare form of cutaneous metastases of breast cancer. The clinical presentation is that of a diffuse indurated carcinomatous infiltration of the skin and subcutaneous tissues of the mammary region and the anterior aspect of the chest. In most cases, breast carcinoma en cuirasse develops post-mastectomy and represents a dramatic presentation of an aggressive tumor associated with a dismal prognosis. Because of the rarity of this type of malignancy, the optimal approach to treatment has not been clearly defined. The systemic treatment has been associated with limited efficacy, and the primary goal is palliative care and preservation of the quality of life through skin-directed therapies. Herein, a very rare case of primary breast carcinoma en cuirasse is presented, along with a review of the literature. Early diagnosis and prompt treatment of any potential skin metastases of breast cancer are essential to prevent the catastrophic natural progression of the disease.

Chronic myeloid leukemia stem cells require cell-autonomous pleiotrophin signaling

Tyrosine kinase inhibitors (TKIs) induce molecular remission in the majority of patients with chronic myelogenous leukemia (CML), but the persistence of CML stem cells hinders cure and necessitates indefinite TKI therapy. We report that CML stem cells upregulate the expression of pleiotrophin (PTN) and require cell-autonomous PTN signaling for CML pathogenesis in BCR/ABL+ mice. Constitutive PTN deletion substantially reduced the numbers of CML stem cells capable of initiating CML in vivo. Hematopoietic cell-specific deletion of PTN suppressed CML development in BCR/ABL+ mice, suggesting that cell-autonomous PTN signaling was necessary for CML disease evolution. Mechanistically, PTN promoted CML stem cell survival and TKI resistance via induction of Jun and the unfolded protein response. Human CML cells were also dependent on cell-autonomous PTN signaling, and anti-PTN antibody suppressed human CML colony formation and CML repopulation in vivo. Our results suggest that targeted inhibition of PTN has therapeutic potential to eradicate CML stem cells.

Estrogen Stimulation of Pleiotrophin Enhances Osteoblast Differentiation and Maintains Bone Mass in IGFBP-2 Null Mice

Insulin-like growth factor binding protein-2 (IGFBP-2) stimulates osteoblast differentiation but only male Igfbp2 null mice have a skeletal phenotype. The trophic actions of IGFBP-2 in bone are mediated through its binding to receptor tyrosine phosphatase beta (RPTPβ). Another important ligand for RPTPβ is pleiotrophin (PTN), which also stimulates osteoblast differentiation. We determined the change in PTN and RPTPβ in Igfbp2-/- mice. Analysis of whole bone mRNA in wild-type and knockout mice revealed increased expression of Ptn. Rptpβ increased in gene-deleted animals with females having greater expression than males. Knockdown of PTN expression in osteoblasts in vitro inhibited differentiation, and addition of PTN to the incubation medium rescued the response. Estradiol stimulated PTN secretion and PTN knockdown blocked estradiol-stimulated differentiation. PTN addition to IGFBP-2 silenced osteoblast stimulated differentiation, and an anti-fibronectin-3 antibody, which inhibits PTN binding to RPTPβ, inhibited this response. Estrogen stimulated PTN secretion and downstream signaling in the IGFBP-2 silenced osteoblasts and these effects were inhibited with anti-fibronectin-3. Administration of estrogen to wild-type and Igfbp2-/- male mice stimulated an increase in both areal bone mineral density and trabecular bone volume fraction but the increase was significantly greater in the Igfbp2-/- animals. Estrogen also stimulated RPTPβ expression in the null mice. We conclude that loss of IGFBP-2 expression is accompanied by upregulation of PTN and RPTPβ expression in osteoblasts, that the degree of increase is greater in females due to estrogen secretion, and that this compensatory change may account for some component of the maintenance of normal bone mass in female mice.

Rapid progression of carcinoma en cuirasse breast dermal metastases on 18F-fludeoxyglucose positron emission tomography-computed tomography

Cancer in the dermis of the breast has a poor prognosis. The breast dermis can become malignantly involved primarily in inflammatory breast cancer, through the direct extension of locally advanced breast cancer, or metastatically from an underlying breast mass or a distant primary malignancy (e.g., gastric adenocarcinoma). Breast dermal metastases have the shortest median survival among them. Breast dermal metastases are classified into eight clinicohistopathologic groups, one of which is carcinoma en cuirasse. We present a case of a 52-year-old female with a history of invasive ductal carcinoma, Stage IIIC (pT2N3a), treated with lumpectomy, axillary node dissection, and chemoradiation therapy that recurred as carcinoma en cuirasse breast dermal metastases. Through ¹⁸F-fludeoxyglucose positron emission tomography–computed tomography (¹⁸F-FDG PET-CT) and clinical images, the case illustrates the rapid progression and devastating consequences of carcinoma en cuirasse breast dermal metastases over a 4-month period despite optimal therapy. Furthermore, the case emphasizes the sensitivity of ¹⁸F-FDG PET-CT to detect pathology in the breast dermis. Finally, the case highlights the crucial role that nuclear medicine physicians play in helping clinical colleagues differentiate between the various breast dermal malignant manifestations and benign mastitis, a common confounder in postradiation patients.

Proteoglycans in brain development and pathogenesis

Proteoglycans are diverse, complex extracellular/cell surface macromolecules composed of a central core protein with covalently linked glycosaminoglycan (GAG) chains; both of these components contribute to the growing list of important bio-active functions attributed to proteoglycans. Increasingly, attention has been paid to the roles of proteoglycans in nervous tissue development due to their highly regulated spatio/temporal expression patterns, whereby they promote/inhibit neurite outgrowth, participate in specification and maturation of various precursor cell types, and regulate cell behaviors like migration, axonal pathfinding, synaptogenesis and plasticity. These functions emanate from both the environments proteoglycans create around cells by retaining ions and water or serving as scaffolds for cell shaping or motility, and from dynamic interactions that modulate signaling fields for cytokines, growth factors and morphogens, which may bind to either the protein or GAG portions. Also, genetic abnormalities impacting proteoglycan synthesis during critical steps of brain development and response to environmental insults and injuries, as well as changes in microenvironment interactions leading to tumors in the central nervous system, all suggest roles for proteoglycans in behavioral and intellectual disorders and malignancies.

Pleiotrophin exerts its migration and invasion effect through the neuropilin-1 pathway

Pleiotrophin (PTN) is a pleiotropic growth factor that exhibits angiogenic properties and is involved in tumor growth and metastasis. Although it has been shown that PTN is expressed in tumor cells, few studies have investigated its receptors and their involvement in cell migration and invasion. Neuropilin-1 (NRP-1) is a receptor for multiple growth factors that mediates cell motility and plays an important role in angiogenesis and tumor progression. Here we provide evidence for the first time that NRP-1 is crucial for biological activities of PTN. We found that PTN interacted directly with NRP-1 through its thrombospondin type-I repeat domains. Importantly, binding of PTN to NRP-1 stimulated the internalization and recycling of NRP-1 at the cell surface. Invalidation of NRP-1 by RNA interference in human carcinoma cells inhibited PTN-induced intracellular signaling of the serine-threonine kinase, mitogen-activated protein MAP kinase, and focal adhesion kinase pathways. Accordingly, NRP-1 silencing or blocking by antibody inhibited PTN-induced human umbilical vein endothelial cell migration and tumor cell invasion. These results suggest that NRP-1/PTN interaction provides a novel mechanism for controlling the response of endothelial and tumoral cells to PTN and may explain, at least in part, how PTN contributes to tumor angiogenesis and cancer progression.

Structural studies reveal an important role for the pleiotrophin C-terminus in mediating interactions with chondroitin sulfate

Pleiotrophin (PTN) is a potent glycosaminoglycan-binding cytokine that is important in neural development, angiogenesis and tissue regeneration. Much of its activity is attributed to its interactions with the chondroitin sulfate (CS) proteoglycan, receptor type protein tyrosine phosphatase ζ (PTPRZ). However, there is little high resolution structural information on the interactions between PTN and CS, nor is it clear why the C-terminal tail of PTN is necessary for signaling through PTPRZ, even though it does not contribute to heparin binding. We determined the first structure of PTN and analyzed its interactions with CS. Our structure shows that PTN possesses large basic surfaces on both of its structured domains and also that residues in the hinge segment connecting the domains have significant contacts with the C-terminal domain. Our analysis of PTN-CS interactions showed that the C-terminal tail of PTN is essential for maintaining stable interactions with chondroitin sulfate A, the type of CS commonly found on PTPRZ. These results offer the first possible explanation of why truncated PTN missing the C-terminal tail is unable to signal through PTPRZ. NMR analysis of the interactions of PTN with CS revealed that the C-terminal domain and hinge of PTN make up the major CS-binding site in PTN, and that removal of the C-terminal tail weakened the affinity of the site for CSA but not for other high sulfation density CS.

DATABASE

Coordinates of the ensemble of ten PTN structures have been deposited in RCSB under accession number 2n6f. Chemical shifts assignments and structural constraints have been deposited in BMRB under accession number 25762.

Effects of Pleiotrophin on endothelial and inflammatory cells: Pro-angiogenic and anti-inflammatory properties and potential role for vascular bio-prosthesis endothelialization

PURPOSE

One of the limitations emerged with both synthetic and degradable vascular grafts is the lack of endothelialization after implantation that is known to be the main reason leading to unfavourable outcomes. It emerges the need to find new strategies to promote a rapid endothelialization of the scaffold. Pleiotrophin is a growth/differentiation cytokine for various cell type. We here evaluated the effect of Pleiotrophin on endothelial cells (EC), monocytes and macrophages that have been shown as key cells promoting neovascularization.

MATERIAL/METHODS

EA.hy926 endothelial cells, THP-1 monocytes and PMA-differentiated macrophages were treated with Pleiotrophin (10 and 100ng/ml). VEGF, Flk-1, Nrp-1, COX-2, ICAM-1 and TGFβ expression were detected by Western Blot, IL-10, MCP-1 and TNFα levels by ELISA. Chemotaxis was performed in Boyden chambers. Wound healing was performed by scratch wound assay.

RESULTS

Pleiotrophin induces in EC the expression of VEGF and its receptors Flk-1 and Nrp-1 and improves the migratory capacity. In THP-1 monocytes, Pleiotrophin induces the expression of VEGF and its receptor Nrp-1 and decreases the levels of COX-2 and TNFα. In PMA-differentiated macrophages COX-2 expression was significantly reduced by Pleiotrophin, while IL-10 and TGFβ were increased.

CONCLUSIONS

Pleiotrophin acts as an angiogenesis 'driver' by promoting the creation of a pro-angiogenic environment, a migratory behaviour in EC and a pro-regenerative alternative phenotype in macrophages. Our results suggest that Pleiotrophin might be considered for vascular prosthesis engineering.

Proteoglycans and neuronal migration in the cerebral cortex during development and disease

Chondroitin sulfate proteoglycans and heparan sulfate proteoglycans are major constituents of the extracellular matrix and the cell surface in the brain. Proteoglycans bind with many proteins including growth factors, chemokines, axon guidance molecules, and cell adhesion molecules through both the glycosaminoglycan and the core protein portions. The functions of proteoglycans are flexibly regulated due to the structural variability of glycosaminoglycans, which are generated by multiple glycosaminoglycan synthesis and modifying enzymes. Neuronal cell surface proteoglycans such as PTPζ, neuroglycan C and syndecan-3 function as direct receptors for heparin-binding growth factors that induce neuronal migration. The lectican family, secreted chondroitin sulfate proteoglycans, forms large aggregates with hyaluronic acid and tenascins, in which many signaling molecules and enzymes including matrix proteases are preserved. In the developing cerebrum, secreted chondroitin sulfate proteoglycans such as neurocan, versican and phosphacan are richly expressed in the areas that are strategically important for neuronal migration such as the striatum, marginal zone, subplate and subventricular zone in the neocortex. These proteoglycans may anchor various attractive and/or repulsive cues, regulating the migration routes of inhibitory neurons. Recent studies demonstrated that the genes encoding proteoglycan core proteins and glycosaminoglycan synthesis and modifying enzymes are associated with various psychiatric and intellectual disorders, which may be related to the defects of neuronal migration.

The molecular signature of the stroma response in prostate cancer-induced osteoblastic bone metastasis highlights expansion of hematopoietic and prostate epithelial stem cell niches

The reciprocal interaction between cancer cells and the tissue-specific stroma is critical for primary and metastatic tumor growth progression. Prostate cancer cells colonize preferentially bone (osteotropism), where they alter the physiological balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption, and elicit prevalently an osteoblastic response (osteoinduction). The molecular cues provided by osteoblasts for the survival and growth of bone metastatic prostate cancer cells are largely unknown. We exploited the sufficient divergence between human and mouse RNA sequences together with redefinition of highly species-specific gene arrays by computer-aided and experimental exclusion of cross-hybridizing oligonucleotide probes. This strategy allowed the dissection of the stroma (mouse) from the cancer cell (human) transcriptome in bone metastasis xenograft models of human osteoinductive prostate cancer cells (VCaP and C4-2B). As a result, we generated the osteoblastic bone metastasis-associated stroma transcriptome (OB-BMST). Subtraction of genes shared by inflammation, wound healing and desmoplastic responses, and by the tissue type-independent stroma responses to a variety of non-osteotropic and osteotropic primary cancers generated a curated gene signature ("Core" OB-BMST) putatively representing the bone marrow/bone-specific stroma response to prostate cancer-induced, osteoblastic bone metastasis. The expression pattern of three representative Core OB-BMST genes (PTN, EPHA3 and FSCN1) seems to confirm the bone specificity of this response. A robust induction of genes involved in osteogenesis and angiogenesis dominates both the OB-BMST and Core OB-BMST. This translates in an amplification of hematopoietic and, remarkably, prostate epithelial stem cell niche components that may function as a self-reinforcing bone metastatic niche providing a growth support specific for osteoinductive prostate cancer cells. The induction of this combinatorial stem cell niche is a novel mechanism that may also explain cancer cell osteotropism and local interference with hematopoiesis (myelophthisis). Accordingly, these stem cell niche components may represent innovative therapeutic targets and/or serum biomarkers in osteoblastic bone metastasis.

PTN signaling: Components and mechanistic insights in human ovarian cancer

Molecular vulnerabilities represent promising candidates for the development of targeted therapies that hold the promise to overcome the challenges encountered with non-targeted chemotherapy for the treatment of ovarian cancer. Through a synthetic lethality screen, we previously identified pleiotrophin (PTN) as a molecular vulnerability in ovarian cancer and showed that siRNA-mediated PTN knockdown induced apoptotic cell death in epithelial ovarian cancer (EOC) cells. Although, it is well known that PTN elicits its pro-tumorigenic effects through its receptor, protein tyrosine phosphatase receptor Z1 (PTPRZ1), little is known about the potential importance of this pathway in the pathogenesis of ovarian cancer. In this study, we show that PTN is expressed, produced, and secreted in a panel of EOC cell lines. PTN levels in serous ovarian tumor tissues are on average 3.5-fold higher relative to normal tissue and PTN is detectable in serum samples of patients with EOC. PTPRZ1 is also expressed and produced by EOC cells and is found to be up-regulated in serous ovarian tumor tissue relative to normal ovarian surface epithelial tissue (P < 0.05). Gene silencing of PTPRZ1 in EOC cell lines using siRNA-mediated knockdown shows that PTPRZ1 is essential for viability and results in significant apoptosis with no effect on the cell cycle phase distribution. In order to determine how PTN mediates survival, we silenced the gene using siRNA mediated knockdown and performed expression profiling of 36 survival-related genes. Through computational mapping of the differentially expressed genes, members of the MAPK (mitogen-activated protein kinase) family were found to be likely effectors of PTN signaling in EOC cells. Our results provide the first experimental evidence that PTN and its signaling components may be of significance in the pathogenesis of epithelial ovarian cancer and provide a rationale for clinical evaluation of MAPK inhibitors in PTN and/or PTPRZ1 expressing ovarian tumors.

Targeting midkine and pleiotrophin signalling pathways in addiction and neurodegenerative disorders: recent progress and perspectives

Midkine (MK) and pleiotrophin (PTN) are two neurotrophic factors that are highly up-regulated in different brain regions after the administration of various drugs of abuse and in degenerative areas of the brain. A deficiency in both MK and PTN has been suggested to be an important genetic factor, which confers vulnerability to the development of the neurodegenerative disorders associated with drugs of abuse in humans. In this review, evidence demonstrating that MK and PTN limit the rewarding effects of drugs of abuse and, potentially, prevent drug relapse is compiled. There is also convincing evidence that MK and PTN have neuroprotective effects against the neurotoxicity and development of neurodegenerative disorders induced by drugs of abuse. Exogenous administration of MK and/or PTN into the CNS by means of non-invasive methods is proposed as a novel therapeutic strategy for addictive and neurodegenerative diseases. Identification of new molecular targets downstream of the MK and PTN signalling pathways or pharmacological modulation of those already known may also provide a more traditional, but probably effective, therapeutic strategy for treating addictive and neurodegenerative disorders.

LINKED ARTICLES

This article is part of a themed section on Midkine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-4.

Transcriptome sequencing reveals differences between primary and secondary hair follicle-derived dermal papilla cells of the Cashmere goat (Capra hircus)

The dermal papilla is thought to establish the character and control the size of hair follicles. Inner Mongolia Cashmere goats (Capra hircus) have a double coat comprising the primary and secondary hair follicles, which have dramatically different sizes and textures. The Cashmere goat is rapidly becoming a potent model for hair follicle morphogenesis research. In this study, we established two dermal papilla cell lines during the anagen phase of the hair growth cycle from the primary and secondary hair follicles and clarified the similarities and differences in their morphology and growth characteristics. High-throughput transcriptome sequencing was used to identify gene expression differences between the two dermal papilla cell lines. Many of the differentially expressed genes are involved in vascularization, ECM-receptor interaction and Wnt/β-catenin/Lef1 signaling pathways, which intimately associated with hair follicle morphogenesis. These findings provide valuable information for research on postnatal morphogenesis of hair follicles.

The pleiotrophin-ALK axis is required for tumorigenicity of glioblastoma stem cells

Increasing evidence suggests that brain tumors arise from the transformation of neural stem/precursor/progenitor cells. Much current research on human brain tumors is focused on the stem-like properties of glioblastoma. Here we show that anaplastic lymphoma kinase (ALK) and its ligand pleiotrophin are required for the self-renewal and tumorigenicity of glioblastoma stem cells (GSCs). Furthermore, we demonstrate that pleiotrophin is transactivated directly by SOX2, a transcription factor essential for the maintenance of both neural stem cells and GSCs. We speculate that the pleiotrophin-ALK axis may be a promising target for the therapy of glioblastoma.

Isolated central nervous system progression on Crizotinib: an Achilles heel of non-small cell lung cancer with EML4-ALK translocation?

Advanced non-small lung cancer (NSCLC) remains almost uniformly lethal with marginal long-term survival despite efforts to target specific oncogenic addiction pathways that may drive these tumors with small molecularly targeted agents and biologics. The EML4-ALK fusion gene encodes a chimeric tyrosine kinase that activates the Ras signaling pathway, and this fusion protein is found in approximately 5% of NSCLC. Targeting EML4-ALK with Crizotinib in this subset of NSCLC has documented therapeutic efficacy, but the vast majority of patients eventually develop recurrent disease that is often refractory to further treatments. We present the clinicopathologic features of three patients with metastatic NSCLC harboring the EML4-ALK translocation that developed isolated central nervous system (CNS) metastases in the presence of good disease control elsewhere in the body. These cases suggest a differential response of NSCLC to Crizotinib in the brain in comparison to other sites of disease, and are consistent with a previous report of poor CNS penetration of Crizotinib. Results of ongoing clinical trials will clarify whether the CNS is a major sanctuary site for EML4-ALK positive NSCLC being treated with Crizotinib. While understanding molecular mechanisms of resistance is critical to overcome therapeutic resistance, understanding physiologic mechanisms of resistance through analyzing anatomic patterns of failure may be equally crucial to improve long-term survival for patients with EML4-ALK translocation positive NSCLC.

Potential role for PAD2 in gene regulation in breast cancer cells

The peptidylarginine deiminase (PAD) family of enzymes post-translationally convert positively charged arginine residues in substrate proteins to the neutral, non-standard residue citrulline. PAD family members 1, 2, 3, and 6 have previously been localized to the cell cytoplasm and, thus, their potential to regulate gene activity has not been described. We recently demonstrated that PAD2 is expressed in the canine mammary gland epithelium and that levels of histone citrullination in this tissue correlate with PAD2 expression. Given these observations, we decided to test whether PAD2 might localize to the nuclear compartment of the human mammary epithelium and regulate gene activity in these cells. Here we show, for the first time, that PAD2 is specifically expressed in human mammary gland epithelial cells and that a portion of PAD2 associates with chromatin in MCF-7 breast cancer cells. We investigated a potential nuclear function for PAD2 by microarray, qPCR, and chromatin immunoprecipitation analysis. Results show that the expression of a unique subset of genes is disregulated following depletion of PAD2 from MCF-7 cells. Further, ChIP analysis of two of the most highly up- and down-regulated genes (PTN and MAGEA12, respectively) found that PAD2 binds directly to these gene promoters and that the likely mechanism by which PAD2 regulates expression of these genes is via citrullination of arginine residues 2-8-17 on histone H3 tails. Thus, our findings define a novel role for PAD2 in gene expression in human mammary epithelial cells.

Menin represses malignant phenotypes of melanoma through regulating multiple pathways

Substantial genetic evidence suggests that chromosome 11q is involved in regulating initiation and progression of malignant melanomas. Mutations of the MEN1 gene, located in chromosome 11q13, predispose individuals to the multiple endocrine neoplasia type 1 (MEN1) familial syndrome. MEN1 patients develop primary malignant melanoma, suggesting a potential link between MEN1 syndrome and development of melanomas, but the precise molecular mechanism is poorly understood. Here we show that the MEN1 gene suppresses malignant phenotypes of melanoma cells through multiple signalling pathways. Ectopic expression of menin, the product of MEN1 gene, significantly inhibited melanoma cell proliferation and migration in vitro and in vivo. The inhibition was partly achieved through suppressing expression of growth factor pleiotrophin (PTN) and receptor protein tyrosine phosphatase (RPTP) β/ζ, accompanied with the reduced expression of phosphatidylinositol 3-kinase (pI3K) and decreased phosphorylation of focal adhesion kinase (FAK) and extracellular signal regulated kinase (ERK1/2). Interestingly, reduced expression of menin was associated with hypermethylation of the CpG islands of the MEN1 promoter in melanoma cells. Taken together, these findings suggest a previously unappreciated function for menin in suppressing malignant phenotypes of melanomas and unravel a novel mechanism involving in regulating PTN signalling by menin in development and progression of melanomas.

Chicken pleiotrophin: regulation of tissue specific expression by estrogen in the oviduct and distinct expression pattern in the ovarian carcinomas

Pleiotrophin (PTN) is a developmentally-regulated growth factor which is widely distributed in various tissues and also detected in many kinds of carcinomas. However, little is known about the PTN gene in chickens. In the present study, we found chicken PTN to be highly conserved with respect to mammalian PTN genes (91–92.6%) and its mRNA was most abundant in brain, heart and oviduct. This study focused on the PTN gene in the oviduct where it was detected in the glandular (GE) and luminal (LE) epithelial cells. Treatment of young chicks with diethylstilbesterol induced PTN mRNA and protein in GE and LE, but not in other cell types of the oviduct. Further, several microRNAs, specifically miR-499 and miR-1709 were discovered to influence PTN expression via its 3′-UTR which suggests that post-transcriptional regulation influences PTN expression in chickens. We also compared expression patterns and CpG methylation status of the PTN gene in normal and cancerous ovaries from chickens. Our results indicated that PTN is most abundant in the GE of adenocarcinoma of cancerous, but not normal ovaries of hens. Bisulfite sequencing revealed that 30- and 40% of −1311 and −1339 CpG sites are demethylated in ovarian cancer cells, respectively. Collectively, these results indicate that chicken PTN is a novel estrogen-induced gene expressed mainly in the oviductal epithelia implicating PTN regulation of oviduct development and egg formation, and also suggest that PTN is a biomarker for epithelial ovarian carcinoma that could be used for diagnosis and monitoring effects of therapies for the disease.

PAX3-FKHR regulates the expression of pleiotrophin to mediate motility in alveolar rhabdomyosarcoma cells

More than 80% of the aggressive alveolar rhabdomyosarcoma (ARMSs) harbor a PAX3-FKHR fusion transcription factor, which regulates cell motility and promotes metastasis. Our hypothesis is that PAX3-FKHR regulates cell motility by regulating the expression of its transcriptional targets that are also its downstream effectors, which if identified, may lead to novel therapeutic approaches for treating ARMS. Here we report that PAX3-FKHR regulates the expression of pleiotrophin (PTN) by binding specifically to a paired-box domain binding-site in the PTN promoter, indicating that PTN is a transcriptional target of PAX3-FKHR. Significantly, we show that PTN regulates ARMS cell motility. Taken together, we have identified PTN as a novel transcriptional target of PAX3-FKHR that promotes ARMS cell motility. PTN may be a novel therapeutic target for the treatment of ARMS.

Stromal pleiotrophin regulates repopulation behavior of hematopoietic stem cells

Pleiotrophin (Ptn) is strongly expressed by stromal cells which maintain HSCs. However, in vivo, Ptn deficiency does not alter steady-state hematopoiesis. However, knockdown of Ptn (Ptn(KD)) in stromal cells increases production of hematopoietic progenitors as well as HSC activity in cocultures, suggesting that Ptn may have a role in HSC activation. Indeed, transplantations of wild-type (Ptn(+/+)) HSCs into Ptn(-/-) mice show increased donor cell production in serial transplantations and dominant myeloid regeneration caused by Ptn-dependent regulation of HSC repopulation behavior. This regulation of Lin(-)Kit(+)Sca1(+) function is associated with increased proliferation and, on a molecular level, with up-regulated expression of cyclin D1 (Ccnd1) and C/EBPα (Cepba), but reduced of PPARγ. The known HSC regulator β-catenin is, however, not altered in the absence of Ptn. In conclusion, our results point to different Ptn-mediated regulatory mechanisms in normal hemostasis and in hematopoietic regeneration and in maintaining the balance of myeloid and lymphoid regeneration. Moreover, our results support the idea that microenvironmental Ptn regulates hematopoietic regeneration through β-catenin-independent regulation of Ccnd1 and Cebpa.

Effect of sitagliptin plus metformin on β-cell function, islet integrity and islet gene expression in Zucker diabetic fatty rats

AIM

The combination of metformin and a dipeptidyl peptidase 4 (DPP-4) inhibitor has been shown to be an effective, safe, and well-tolerated treatment for type 2 diabetes. We evaluated β-cell function and morphological changes in islets in Zucker diabetic fatty (ZDF) rats following combined therapy with sitagliptin and metformin and investigated the expression of potentially relevant genes using cDNA microarrays.

METHODS

Nine-week-old ZDF rats were randomly divided into four treatment groups: no treatment (control); sitagliptin; metformin, and sitagliptin plus metformin. After 5 weeks of treatment, an oral glucose tolerance test was performed and plasma levels of active GLP-1 and islet morphology and gene expression were assessed.

RESULTS

Combination therapy reduced fasting glucose and postprandial plasma glucose levels and increased active GLP-1 levels, compared with monotherapy. Combination therapy also increased insulin secretion, the proportion of small islets, and the intensity of insulin staining. Furthermore, it increased the expression of genes involved in cell survival and growth and downregulated apoptosis-associated genes, relative to monotherapy.

CONCLUSIONS

Combination treatment with sitagliptin and metformin preserved β-cell function and β-cell integrity in ZDF rats. This may be associated with the transcriptional activation of anti-apoptotic and pro-survival genes, as well as the suppression of pro-apoptotic genes.

Expression of pleiotrophin in the prostate is androgen regulated and it functions as an autocrine regulator of mesenchyme and cancer associated fibroblasts and as a paracrine regulator of epithelia

BACKGROUND

Androgens and paracrine signaling from mesenchyme/stroma regulate development and disease of the prostate, and gene profiling studies of inductive prostate mesenchyme have identified candidate molecules such as pleiotrophin (Ptn).

METHODS

Ptn transcripts and protein were localized by in situ and immunohistochemistry and Ptn mRNA was quantitated by Northern blot and qRT-PCR. Ptn function was examined by addition of hPTN protein to rat ventral prostate organ cultures, primary human fetal prostate fibroblasts, prostate cancer associated fibroblasts, and BPH1 epithelia.

RESULTS

During development, Ptn transcripts and protein were expressed in ventral mesenchymal pad (VMP) and prostatic mesenchyme. Ptn was localized to mesenchyme surrounding ductal epithelial tips undergoing branching morphogenesis, and was located on the surface of epithelia. hPTN protein stimulated branching morphogenesis and stromal and epithelial proliferation, when added to rat VP cultures, and also stimulated growth of fetal human prostate fibroblasts, prostate cancer associated fibroblasts, and BPH1 epithelia. PTN mRNA was enriched in patient-matched normal prostate fibroblasts versus prostate cancer associated fibroblasts. PTN also showed male enriched expression in fetal human male urethra versus female, and between wt male and ARKO male mice. Transcripts for PTN were upregulated by testosterone in fetal human prostate fibroblasts and organ cultures of female rat VMP. Ptn protein was increased by testosterone in organ cultures of female rat VMP and in rat male urethra compared to female.

CONCLUSIONS

Our data suggest that in the prostate Ptn functions as a regulator of both mesenchymal and epithelial proliferation, and that androgens regulate Ptn levels.

The pursuit of oncotargets through understanding defective cell regulation

More effective anticancer agents are essential, as has too often been demonstrated by the paucity of therapeutics which preserve life. Their discovery is very difficult. Many approaches are being applied, from testing folk medicines to automated high throughput screening of large chemical libraries. Mutations in cancer cells create dysfunctional regulatory systems. This Perspective summarizes an approach to applying defective molecular control mechanisms as oncotargets on which drug discoveries against cancer can be based.

The pursuit of oncotargets through understanding defective cell regulation

More effective anticancer agents are essential, as has too often been demonstrated by the paucity of therapeutics which preserve life. Their discovery is very difficult. Many approaches are being applied, from testing folk medicines to automated high throughput screening of large chemical libraries. Mutations in cancer cells create dysfunctional regulatory systems. This Perspective summarizes an approach to applying defective molecular control mechanisms as oncotargets on which drug discoveries against cancer can be based.

Histone lysine methylation and demethylation pathways in cancer

The genetic changes leading to the development of human cancer are accompanied by alterations in the structure and modification status of chromatin, which represent powerful regulatory mechanisms for gene expression and genome stability. These epigenetic alterations have sparked interest into deciphering the regulatory pathways and function of post-translational modifications of histones during the initiation and progression of cancer. In this review we describe and summarize the current knowledge of several histone lysine methyltransferase and demethylase pathways relevant to cancer. Mechanistic insight into histone modifications will pave the way for the development and therapeutic application of "epidrugs" in cancer.

Lung cancer cell migration is regulated via repressing growth factor PTN/RPTP β/ζ signaling by menin

Menin encoded by the multiple endocrine neoplasia type 1 (MEN1) gene is associated with chromatin and the nuclear matrix and exerts multiple biological functions including regulation of cell proliferation and adhesion. Men1 mutations increase the likelihood of lung cancer development in mice. Menin expression is reduced in certain human non-small cell lung cancer cells, and reduction of menin is closely correlated with increased lung cancer metastasis to lymph nodes. However, it is poorly understood whether menin affects migration of lung cancer cells. In this study, we show that menin-regulated A549 lung cancer cell migration, which was mediated by growth factor pleiotrophin (PTN) and its cell surface receptor, protein tyrosine phosphatase beta/zeta (RPTP β/ζ). Ectopic menin expression significantly repressed PTN transcription, but indirectly inhibited RPTP β/ζ expression through repressing PTN expression. Further studies revealed that menin-regulated cell migration through PTN/RPTP β/ζ, in conjunction with integrin α_vβ₃, focal adhesion kinase, phosphatidylinositol 3-kinase and phosphorylated extracellular signal regulated kinase 1/2. These findings provide mechanistic insights into the molecular basis for menin/PTN-mediated regulation of A549 lung cancer cell migration.

VEGF and pleiotrophin modulate the immune profile of breast cancer

Angiogenesis, the sprouting of the existing vascular network to form new vessels, is required for the growth of solid tumors. For this reason, the primary stimulant of angiogenesis, vascular endothelial growth factor-A (VEGF), is an attractive target for tumor therapy. In fact, there are currently numerous anti-VEGF therapies in clinical development for the treatment of various cancers, including breast cancer. VEGF signals through two primary VEGF receptors, VEGFR1 and VEGFR2. VEGFR2 is the primary angiogenic receptor, and VEGFR1 has been implicated in macrophage chemotaxis and tumor cell survival and invasion. It has only been appreciated recently that the VEGFRs are expressed not only on endothelial cells and tumor cells but also on many host immune cells. Therefore, to better understand the effects of anti-VEGF therapy it is important to consider the effects of VEGF on all cells in the tumor microenvironment, including immune cells. Bevacizumab (Avastin^®, Genetech), which binds VEGF and inhibits interaction with VEGFR1 and VEGFR2, was approved for the treatment of metastatic HER2/NEU-negative breast cancer in 2008, however, the majority of human mammary tumors are either innately resistant or will acquire resistance to anti-VEGF therapy. This suggests that these tumors activate alternate angiogenesis pathways. Pleiotrophin (PTN) is an important angiogenic cytokine in breast cancer and is expressed at high levels in approximately 60% of human breast tumors. PTN functions as an angiogenic factor and promotes remodeling of the tumor microenvironment as well as epithelial-mesenchymal transition (EMT). In addition, PTN can have profound effects on macrophage phenotype. The present review focuses on the functions of VEGF and PTN on immune cell infiltration and function in breast cancer. Furthermore, we will discuss how anti-VEGF therapy modulates the immune cell profile.

Suppression of lung adenocarcinoma through menin and polycomb gene-mediated repression of growth factor pleiotrophin

Menin upregulates transcription of cell-cycle inhibitors to suppress endocrine tumors, but it is poorly understood how menin suppresses non-endocrine tumors such as lung cancer. Here, we show that menin inhibits proliferation of human lung cancer cells and growth of lung cancer in mice. The menin-mediated tumor suppression requires repression of growth factor pleiotrophin (PTN), which binds to its cell surface receptor, anaplastic lymphoma kinase (ALK) that is activated in certain lung adenocarcinomas. Menin represses PTN transcription and PTN-induced proliferation of human lung cancer cells, and menin expression is substantially reduced in primary human lung adenocarcinomas. Notably, menin binds the PTN locus and enhances Polycomb gene Enhancer of Zeste homolog 2 (EZH2)-mediated histone H3 lysine 27 trimethylation (H3K27m3), a negative mark for gene transcription but does not affect histone H3K4 methylation that is usually upregulated by menin in endocrine cells. Together, our findings indicate that menin suppresses lung cancer partly through increasing Polycomb gene-mediated H3K27 methylation and repressing PTN transcription, unraveling a novel, epigenetically regulated PTN-ALK signaling pathway in suppressing lung cancer.

CCL5 secreted by senescent aged fibroblasts induces proliferation of prostate epithelial cells and expression of genes that modulate angiogenesis

There is increased interest in the effects of secretory products from aged cells on promoting both benign and malignant cell growth. We identified a human fibroblast line, AG04382, from an aged donor that naturally demonstrated senescence-associated features and whose conditioned media significantly induced proliferation of benign prostatic hyperplasia (BPH1) cells. Candidate cytokines mediating this effect were identified with protein arrays and validated by ELISA. We found that the AG04382 fibroblast line secreted high levels of CXCL5, CCL5, and CCL2, but relative to the other lines, its conditioned media was unique in its increased expression of CCL5. Blocking studies using specific antibodies against CXCL5, CCL5, and CCL2 in the conditioned media of AG04382 showed that only CCL5 contributed significantly to BPH1 proliferation. Stimulation of BPH1 cells with rhuCCL5 resulted in increased proliferation and migration, as well as significant changes in the expression of genes that influence angiogenesis. These data suggest that CCL5 is a candidate chemokine secreted by aged cells that promotes prostate growth and regulates angiogenesis.

Pleiotrophin is expressed in avian somites and tendon anlagen

Pleiotrophin (Ptn) is a secreted, developmentally regulated growth factor associated with the extracellular matrix. During mammalian embryogenesis, Ptn has been suggested to play a role in the development of various embryonic structures including nervous system and skeleton. In the avian embryo, Ptn has been proposed to be involved in limb cartilage development, but embryonic Ptn expression has not been comprehensively studied. We isolated a cDNA fragment containing the full-length coding sequence of chick Ptn and studied the expression of Ptn in detail until embryonic day 10. We, furthermore, isolated a 6,385-bp phage clone containing the Ptn cDNA of 2,551 bp and additional 3,787 bp downstream of the published Ptn cDNA sequence classifying a yet Ptn-unrelated chEST clone as the 3' untranslated region of Ptn. Our studies revealed novel expression domains in developing somites and during limb formation. We found prominent expression in the somitocoel cells of epithelial somites, and in a sclerotomal subcompartment, the syndetome, which gives rise to the axial tendons in the vertebral motion segment. In the limbs, Ptn was markedly expressed in tendon anlagen and in phalangeal joints. Our results introduce Ptn as a novel marker gene in avian somite and tendon development.

Expression of pleiotrophin and its receptors in human placenta suggests roles in trophoblast life cycle and angiogenesis

Pleiotrophin (PTN) is a heparin-binding protein with multiple activities in cell growth, migration and differentiation mediated through multiple receptors. In mammals, PTN expression in trophoblast is found exclusively in the human and in some of the apes in which an endogenous retrovirus upstream of the first coding exon generates a phylogenetically new trophoblast-specific promoter associated with exon UV3. To understand the functions of ERV promoter-mediated trophoblastic PTN expression in pregnancy, we correlated the expression of PTN and its receptors anaplastic lymphoma kinase (ALK), receptor protein tyrosine phosphatase beta/zeta (RPTPbeta/zeta), and Syndecan-1 and Syndecan-3 (SDC1 and SDC3) with key developmental processes in first-trimester human placentation. In an extensive survey of cell lines and primary tissues, we found that trophoblastic transcription of PTN is initiated exclusively from the ERV promoter, whereas decidual expression is initiated at the phylogenetically ancient U1 exon-associated promoter. Using immunohistochemistry, we found that different patterns of overlapping expression of PTN and its receptors occur in different trophoblast subtypes. Notably, a role in angiogenesis is supported by expression of PTN and its receptors in villous mesenchyme, fetal macrophages and villus core fetal vessels. PTN staining of extravillous cytotrophoblasts and the syncytial microvillous membrane is consistent with increasing levels of PTN, as measured by ELISA, in the maternal bloodstream as pregnancy progresses.