Identification and characterization of a novel protein, periostin, with restricted expression to periosteum and periodontal ligament and increased expression by transforming growth factor beta

Validation of human periodontal ligament-derived cells as a reliable source for cytotherapeutic use

AIM

Periodontal ligament (PDL) is a reliable cell source for periodontal regeneration. In this study, an optimal protocol for the extraction, expansion, and characterization of human PDL (hPDL) cells was examined for clinical trials.

MATERIALS AND METHODS

hPDL tissues were obtained from 41 surgically extracted teeth and digested with enzymes. Human adipose-derived stem cells (hADSCs), bone marrow-derived mesenchymal stem cells (hBMMSCs), and gingival fibroblasts (hGFs) were used for comparison. For each sample, the proliferative capacity, colony-forming ability, alkaline phosphatase activity, differentiation ability, the cell surface antigens, gene expression, and regenerative potential were examined.

RESULTS

hPDL cells were more successfully extracted with collagenase/dispase [29/30 (96.7%)] than with trypsin/EDTA [8/11 (72.7%)], and exhibited osteogenic potential both in vitro and in vivo. The proliferation of hPDL cells was rapid at a low cell density. hPDL cells frequently differentiated into cementoblastic/osteoblastic lineage (∼60%). In contrast, their adipogenic and chondrogenic potentials were lower than those of hADSCs and hBMMSCs. Some genes (NCAM1, S100A4, and periostin) were preferentially expressed in hPDL cells compared with those of hBMMSCs and hGFs. Immunohistochemical studies revealed the expressions of S100A4 and periostin in hPDL tissue.

CONCLUSION

A protocol for the successful cultivation and validation of hPDL cells is proposed for clinical settings.

Alternative splicing in bone following mechanical loading

It is estimated that more than 90% of human genes express multiple mRNA transcripts due to alternative splicing. Consequently, the proteins produced by different splice variants will likely have different functions and expression levels. Several genes with splice variants are known in bone, with functions that affect osteoblast function and bone formation. The primary goal of this study was to evaluate the extent of alternative splicing in a bone subjected to mechanical loading and subsequent bone formation. We used the rat forelimb loading model, in which the right forelimb was loaded axially for 3 min, while the left forearm served as a non-loaded control. Animals were subjected to loading sessions every day, with 24 h between sessions. Ulnae were sampled at 11 time points, from 4 h to 32days after beginning loading. RNA was isolated and mRNA abundance was measured at each time point using Affymetrix exon arrays (GeneChip® Rat Exon 1.0 ST Arrays). An ANOVA model was used to identify potential alternatively spliced genes across the time course, and five alternatively spliced genes were validated with qPCR: Akap12, Fn1, Pcolce, Sfrp4, and Tpm1. The number of alternatively spliced genes varied with time, ranging from a low of 68 at 12h to a high of 992 at 16d. We identified genes across the time course that encoded proteins with known functions in bone formation, including collagens, matrix proteins, and components of the Wnt/β-catenin and TGF-β signaling pathways. We also identified alternatively spliced genes encoding cytokines, ion channels, muscle-related genes, and solute carriers that do not have a known function in bone formation and represent potentially novel findings. In addition, a functional characterization was performed to categorize the global functions of the alternatively spliced genes in our data set. In conclusion, mechanical loading induces alternative splicing in bone, which may play an important role in the response of bone to mechanical loading.

Illuminating the molecular basis of diabetic arteriopathy: a proteomic comparison of aortic tissue from diabetic and healthy rats

Arterial disease is a major diabetic complication, yet the component molecular mechanisms of diabetic arteriopathy remain poorly understood. In order to identify major proteins/pathways implicated in diabetic arteriopathy, we studied the effect of 16-wk untreated streptozotocin-induced diabetes on the rat aortic proteome. Specific protein levels in isolated aortas were compared in six discrete, pair-wise (streptozotocin-diabetic and non-diabetic age-matched controls) experiments in which individual proteins were identified and quantified by iTRAQ combined with LC-MS/MS. A total of 398 unique non-redundant proteins were identified in at least one experiment and 208 were detected in three or more. Between-group comparisons revealed significant changes or trends towards changes in relative abundance of 51 proteins (25 increased, 26 decreased). Differences in levels of selected proteins were supported by Western blotting and/or enzyme assays. The most prominent diabetes-associated changes were in groups of proteins linked to oxidative stress responses and the structure/function of myofibrils and microfilaments. Indexes of mitochondrial content were measurably lower in aortic tissue from diabetic animals. Functional cluster analysis also showed decreased levels of glycolytic enzymes and mitochondrial electron transport system-complex components. These findings newly implicate several proteins/functional pathways in the pathogenesis of arteriosclerosis/diabetic arteriopathy.

Oestrogen regulates proliferation, osteoblastic differentiation, collagen synthesis and periostin gene expression in human periodontal ligament cells through oestrogen receptor beta

OBJECTIVE

The present study was designed to examine how oestrogen regulates proliferation, osteoblastic differentiation, collagen synthesis and periostin gene expression in primary human periodontal ligament (hPDL) cells.

DESIGN

The short interfering RNA (siRNA) technique was used to inhibit oestrogen receptor beta (ERβ) expression hPDL cells. hPDL cell were isolated and fully characterized. A colorimetric assay was applied for the determination of alkaline phosphatase (ALP). An ELISA kit was used to detect osteocalcin (OCN) levels. Collagen synthesis was determined by measuring the incorporation of L-[3H] praline. RT-PCR was performed to detection of periostin mRNA relative gene expression.

RESULTS

ERβ mRNA was expressed in hPDL cells and significant inhibition of mRNA expression and ERβ mature protein of the ERβ was evident in the siRNA group. At 72h, there was a significant increase in non-transfected hPDL cell proliferation after estradiol stimulation. Addition of 17β-estradiol significantly enhanced ALP activity and production of OCN in non-transfected cells but had no effect on collagen synthesis. A clear increase in periostin mRNA expression levels was observed after incubating hPDL cells with estradiol. In hPDL-siERβ cells, the application of estradiol did not produce any evident differences in periostin mRNA expression

CONCLUSIONS

ERβ may play important roles in oestrogen-induced effects on hPDL cell proliferation, osteoblastic differentiation and expression of key molecules for the functional and structural integrity of the periodontium (i.e. periostin).

Spatiotemporal localization of periostin and its potential role in epithelial-mesenchymal transition during palatal fusion

The medial epithelial seam (MES) between the palatal shelves degrades during palatal fusion to achieve the confluence of palatal mesenchyme. Cellular mechanisms underlying the degradation of MES have been proposed, such as apoptosis, epithelial-mesenchymal transition (EMT) and migration of medial edge epithelia (MEE). Extracellular matrix components have been shown to play an important role in EMT in many model systems. Periostin (also known as osteoblast-specific factor-2) is a secreted mesenchymal extracellular matrix component that affects the ability of cells to migrate and/or facilitates EMT during both embryonic development and pathologic conditions. In this study, we evaluated the spatiotemporal expression patterns of periostin during mouse palatal fusion by in situ hybridization and immunofluorescence. Periostin mRNA and protein were present in the palatal mesenchyme, the protein being distributed in a fine fibrillar network and in the basement membrane, but absent from the epithelium. During MES degradation, the protein was strongly expressed in the basement membrane underlying the MES and in some select MEE. Confocal microscopic analysis using an EMT marker, twist1, and an epithelial marker, cytokeratin 14, provided evidence that select MEE were undergoing EMT in association with periostin. Moreover, the major extracellular matrix molecules in basement membrane, laminin and collagen type IV were degraded earlier than periostin. The result is that select MEE establish interactions with periostin in the mesenchymal extracellular matrix, and these new cell-matrix interactions may regulate MEE transdifferentiation during palatal fusion.

Novel isoforms of periostin expressed in the human thyroid

Periostin is an extracellular matrix protein. Five isoforms of human periostin cDNA have been reported, but the expression of periostin isoforms in the human thyroid tissue is by far unknown. A group of primer sets were designed to amplify the full length of cDNA sequence of periostin. Using human thyroid carcinoma and their paired non-neoplastic tissues together with anaplastic thyroid carcinoma cell lines, we examined the presence of periostin cDNA isoforms by RT-PCR and direct DNA sequence analysis. We identified eight coexisting cDNA isoforms in all the tissue samples and cell lines. Three of them were unique to this study. Especially two of them haven’t been previously reported in any species. The eight periostin isoforms differ in the C-terminus from exon XII to exon XXI where alternative splicing usually happens. This is the first report that demonstrates all the eight isoforms of periostin cDNA expressed in the human thyroid gland and identifies three novel isoforms.

Defining central themes in breast cancer biology by differential proteomics: conserved regulation of cell spreading and focal adhesion kinase

Breast cancer is a highly heterogeneous disease, an observation that underscores the importance of elucidating conserved molecular characteristics, such as gene and protein expression, across breast cancer cell types toward providing a greater understanding of context-specific features central to this disease. Motivated by the goal of defining central biological themes across breast cancer cell subtypes, we conducted a global proteomic analysis of three breast cancer cell lines, MCF7, SK-BR-3, and MDA-MB-231, and compared these to a model of nontransformed mammary cells (MCF10A). Our results demonstrate modulation of proteins localized to the extracellular matrix, plasma membrane, and nucleus, along with coordinate decreases in proteins that regulate "cell spreading," a cellular event previously shown to be dysregulated in transformed cells. Protein interaction network analysis revealed the clustering of focal adhesion kinase (FAK), a fundamental regulator of cell spreading, with several proteins identified as mutually, differentially abundant across breast cancer cell lines that impact expression and activity of FAK, such as neprilysin and keratin 19. These analyses provide insights into conservation of protein expression across breast cancer cell subtypes, a subset of which warrants further investigation for their roles in the regulation of cell spreading and FAK in breast cancer.

Increased expression and serum levels of the stromal cell-secreted protein periostin in breast cancer bone metastases

Periostin, a matricellular protein, is overexpressed in the stroma of several cancers. The aim of our study was to investigate more specifically whether periostin expression is associated with bone metastases from breast cancer and to determine its source in the affected bone. Nude mice were inoculated with human MDA-B02 breast cancer cells. Bone metastases-bearing mice were treated with zoledronic acid-an antiresorptive drug-or vehicle. Bone metastases were examined for tumor- and stroma-derived periostin expression by quantitative polymerase chain reaction with human- and mouse-specific primers and immunohistochemistry. Serum periostin and conventional bone turnover markers were also measured. MDA-B02 cells did not express periostin both in vitro and in vivo. However, mouse-derived periostin was markedly overexpressed (eightfold) in metastatic legs compared to noninoculated mice. Serum periostin levels were also markedly increased in metastatic mice and correlated with in situ expression levels. Immunostaining showed that periostin derived from the environing stromal cells of bone metastasis. Bone turnover blockade by zoledronic acid markedly decreased osteolytic lesions but only slightly modulated serum periostin levels. Bone metastases from breast cancer induce overexpression of periostin by surrounding stromal cells. Periostin could be a biochemical marker of the early stromal response associated to breast cancer bone metastasis formation.

Development of a new ELISA for serum periostin: evaluation of growth-related changes and bisphosphonate treatment in mice

Periostin is a gamma-carboxyglutamic acid protein preferentially expressed in periosteum and bone mesenchymal stem cells. Lack of a precise assay for measuring circulating levels impairs the investigation of its biological significance. We developed a new ELISA and studied changes of periostin levels both locally at the bone site and systemically in circulating blood during growth and after bisphosphonate-induced inhibition of bone remodeling in the mouse. The ELISA we developed is based on an affinity-purified polyclonal antibody that was raised against the C-terminal sequence of mouse periostin. Reproducibility, repeatability, precision, and accuracy tests met standards of acceptance. Serum periostin and levels of the bone turnover markers osteocalcin, PINP, CTX-I, and TRAP5b were measured in (1) 4-, 6-, 8-, 10-, and 12-week-old wild-type female Balb/c mice and (2) adult ovariectomized female Balb/c mice treated with zoledronic acid or vehicle. Serum periostin decreased during growth and stabilized from 8 weeks and older, its levels correlating with bone turnover markers. Immunohistochemistry in bones from different growth stages showed that periostin localized specifically at the sites of endochondral and intramembranous ossification, especially at the periosteal envelopes. Zoledronic acid induced a marked decrease in bone remodeling markers but did not alter serum periostin levels or periostin immunostaining pattern. The novel ELISA is highly specific and allows accurate and precise measurements of serum periostin levels in mice.

Role of TNF alpha and PLF in bone remodeling in a rat model of repetitive reaching and grasping

We have previously developed a voluntary rat model of highly repetitive reaching that provides an opportunity to study effects of non-weight bearing muscular loads on bone and mechanisms of naturally occurring inflammation on upper limb tissues in vivo. In this study, we investigated the relationship between inflammatory cytokines and matricellular proteins (Periostin-like-factor, PLF, and connective tissue growth factor, CTGF) using our model. We also examined the relationship between inflammatory cytokines, PLF and bone formation processes. Rats underwent initial training for 5 weeks, and then performed a high repetition high force (HRHF) task (12 reaches/min, 60% maximum grip force, 2 h/day, 3 days/week) for 6 weeks. We then examined the effect of training or task performance with or without treatment with a rat specific TNFalpha antibody on inflammatory cytokines, osteocalcin (a bone formation marker), PLF, CTGF, and behavioral indicators of pain or discomfort. The HRHF task decreased grip strength and induced forepaw mechanical hypersensitivity in both trained control and 6-week HRHF animals. Two weeks of anti-TNFalpha treatment improved grip strength in both groups, but did not ameliorate forepaw hypersensitivity. Moreover, anti-TNFalpha treatment attenuated task-induced increases in inflammatory cytokines (TNFalpha, IL-1alpha, and MIP2 in serum; TNFalpha in forelimb bone and muscles) and serum osteocalcin in 6-week HRHF animals. PLF levels in forelimb bones and flexor digitorum muscles increased significantly in 6-week HRHF animals, increases attenuated by anti-TNFalpha treatment. CTGF levels were unaffected by task performance or anti-TNFalpha treatment in 6-week HRHF muscles. In primary osteoblast cultures, TNFalpha, MIP2 and MIP3a treatment increased PLF levels in a dose dependent manner. Also in primary osteoblast cultures, increased PLF promoted proliferation and differentiation, the latter assessed by measuring Runx2, alkaline phosphatase (ALP) and osteocalcin mRNA levels; ALP activity; as well as calcium deposition and mineralization. Increased PLF also promoted cell adhesion in MC3T3-E1 osteoblast-like cell cultures. Thus, tissue loading in vivo resulted in increased TNFalpha, which increased PLF, which then induced anabolic bone formation, the latter results confirmed in vitro.

Periostin associates with Notch1 precursor to maintain Notch1 expression under a stress condition in mouse cells

Background

Matricellular proteins, including periostin, modulate cell-matrix interactions and cell functions by acting outside of cells.

Methods and Findings

In this study, however, we reported that periostin physically associates with the Notch1 precursor at its EGF repeats in the inside of cells. Moreover, by using the periodontal ligament of molar from periostin-deficient adult mice (Pn−/− molar PDL), which is a constitutively mechanically stressed tissue, we found that periostin maintained the site-1 cleaved 120-kDa transmembrane domain of Notch1 (N1™) level without regulating Notch1 mRNA expression. N1™ maintenance in vitro was also observed under such a stress condition as heat and H₂O₂ treatment in periostin overexpressed cells. Furthermore, we found that the expression of a downstream effector of Notch signaling, Bcl-xL was decreased in the Pn−/− molar PDL, and in the molar movement, cell death was enhanced in the pressure side of Pn−/− molar PDL.

Conclusion

These results suggest the possibility that periostin inhibits cell death through up-regulation of Bcl-xL expression by maintaining the Notch1 protein level under the stress condition, which is caused by its physical association with the Notch1 precursor.

Periostin promotes ovarian cancer angiogenesis and metastasis

OBJECTIVE

Perostin (PN) has been found to be overexpressed in a variety of human malignancies including ovarian cancer. In the present study, we investigated PN expression status in a large cohort of ovarian tumors with the focus on biological influence of PN related on ovarian tumor angiogenesis and metastasis.

METHODS

PN expression was determined by cDNA microarray, PN northern blot and PN IHC tissue array analyses. Exogenous PN expression in ovarian cancer cells OVCAR-3 and OV2008 were achieved through retroviral transfection and confirmed by PN western blot and ELISA. The effects of exogenous PN expression on tumor angiogenesis and metastatic growth were accessed in orthotopic mouse models. The in vitro cell adhesion, migration and invasion assays were performed to investigate the potential mechanisms involved in PN's in vivo effects.

RESULTS

PN was frequently overexpressed in ovarian tumors. Higher PN levels significantly correlated with clinical late stages (III/IV) and cancer recurrence. PN was produced by engineered PN-overexpressing cells at levels comparable to that of A2780 cells, an ovarian carcinoma cell line with endogenous PN expression. PN overexpression did not change cell growth rates in vitro; however it significantly promoted intraperitoneal tumor metastatic growth in immunodeficient mice, which was associated with increased tumor angiogenesis and decreased tumor cell apoptosis. In vitro purified PN promoted cell adhesion, migration, and invasion of both human umbilical endothelial cells (HUVECs) and/or ovarian cancer cells.

CONCLUSIONS

Our data indicate PN plays a critical role in both ovarian tumor angiogenesis and metastasis. Thus PN may represent a clinically effective new target for therapy of ovarian cancer.

Mechanism of active eruption of molars in adolescent rats

The mechanism of active eruption of molars was examined in 36 male adolescent Wistar rats. Histological, histochemical [tetracycline (TC) labelling and alkaline phosphatase (ALP) activity], and immunohistochemical [transforming growth factor (TGF)-β1, -β2, and -β3] investigations were conducted of the rat molar areas. Real-time reverse transcription-polymerase chain reaction (RT-PCR) for mRNA of TGF-β was performed on the periodontal ligament (PDL) dissected out by laser capture microdissection. TC labelling lines showed that a considerable amount of bone formation occurred in the alveolar crest region, apical region, and intraradicular septum, indicating that the maxillary molars had moved downward. However, the periodontal fibres revealed a regular arrangement (alveolar crest, horizontal and oblique fibres) during the experimental period. This suggests that new formation of alveolar crest fibres and rearrangement of the periodontal fibres occurred in the PDL. ALP activity was intense on the bone surface and in the PDL. TGF-β1 was also detected in osteoblasts and fibroblasts but less so in cementoblasts. Real-time RT-PCR also demonstrated significant expression of mRNA of TGF-β1 in the PDL, indicating that TGF-β1 was involved in active eruption. These results suggest that active eruption occurs in adolescent rats and can be managed by TGF-β1.

Periostin is a collagen associated bone matrix protein regulated by parathyroid hormone

Periostin is a 90 kDa secreted protein, originally identified in murine osteoblast-like cells, with a distribution restricted to collagen-rich tissues and certain tumors. In this paper, we first analyzed the expression of periostin mRNA and protein in human fetal osteoblasts (hFOB) and human osteosarcoma (hOS) cell lines by RT real-time PCR and Western blot, respectively. The hFOB 1.19 and three hOS (MHM, KPDXM and Eggen) showed highly variable periostin mRNA levels and protein. Second, we showed that the expression of periostin mRNA was inversely related to the cells' abilities to differentiate and mineralize. Then, we investigated the regulation of periostin mRNA in hFOB after siRNA treatment and in mouse primary osteoblasts (mOB) treated with PTH. Knock-down of periostin mRNA, down-regulated PTHrP, but did not affect the expression of other important markers of differentiation such as RUNX2. In addition, periostin mRNA was transiently up-regulated in osteoblasts by PTH. Finally, the localization of periostin and its partially co-localization with collagen 1a1 mRNA and protein was studied in mouse embryos and postnatal pups using in situ hybridization and immunohistochemistry, respectively. In conclusion, the present study provides novel observations related to the expression, distribution and regulation of periostin in bone cells and extracellular matrix.

Periostin, discovered by nano-flow liquid chromatography and mass spectrometry, is a novel marker of diabetic retinopathy

Diabetes can lead to serious microvascular complications including proliferative diabetic retinopathy (PDR), the leading cause of blindness in adults. Recent studies using gene array technology have attempted to apply a hypothesis-generating approach to elucidate the pathogenesis of PDR, but these studies rely on mRNA differences, which may or may not be related to significant biological processes. To better understand the basic mechanisms of PDR and to identify potential new biomarkers, we performed shotgun liquid chromatography (LC)/tandem mass spectrometry (MS/MS) analysis on pooled protein extracts from neovascular membranes obtained from PDR specimens and compared the results with those from non-vascular epiretinal membrane (ERM) specimens. We detected 226 distinct proteins in neovascular membranes and 154 in ERM. Among these proteins, 102 were specific to neovascular membranes and 30 were specific to ERM. We identified a candidate marker, periostin, as well as several known PDR markers such as pigment epithelium-derived factor (PEDF). We then performed RT-PCR using these markers. The expression of periostin was significantly up-regulated in proliferative membrane specimens. Periostin induces cell attachment and spreading and plays a role in cell adhesion. Proteomic analysis by LC/MS/MS, which permits accurate quantitative comparison, was useful in identifying new candidates such as periostin potentially involved in the pathogenesis of PDR.

Periostin advances atherosclerotic and rheumatic cardiac valve degeneration by inducing angiogenesis and MMP production in humans and rodents

Valvular heart disease (VHD) is the term given to any disease process involving one or more of the heart valves. The condition can be congenital or acquired, for example as a result of atherosclerosis or rheumatic fever. Despite its clinical importance, the molecular mechanisms underlying VHD remain unknown. We investigated the pathophysiologic role and molecular mechanism of periostin, a protein that plays critical roles in cardiac valve development, in degenerative VHD. Unexpectedly, we found that periostin levels were drastically increased in infiltrated inflammatory cells and myofibroblasts in areas of angiogenesis in human atherosclerotic and rheumatic VHD, whereas periostin was localized to the subendothelial layer in normal valves. The expression patterns of periostin and chondromodulin I, an angioinhibitory factor that maintains cardiac valvular function, were mutually exclusive. In WT mice, a high-fat diet markedly increased aortic valve thickening, annular fibrosis, and MMP-2 and MMP-13 expression levels, concomitant with increased periostin expression; these changes were attenuated in periostin-knockout mice. In vitro and ex vivo studies revealed that periostin promoted tube formation and mobilization of ECs. Furthermore, periostin prominently increased MMP secretion from cultured valvular interstitial cells, ECs, and macrophages in a cell type-specific manner. These findings indicate that, in contrast to chondromodulin I, periostin plays an essential role in the progression of cardiac valve complex degeneration by inducing angiogenesis and MMP production.

Periostin is up-regulated in high grade and high stage prostate cancer

BACKGROUND

Expression of periostin is an indicator of epithelial-mesenchymal transition in cancer but a detailed analysis of periostin expression in prostate cancer has not been conducted so far.

METHODS

Here, we evaluated periostin expression in prostate cancer cells and peritumoural stroma immunohistochemically in two independent prostate cancer cohorts, including a training cohort (n = 93) and a test cohort (n = 325). Metastatic prostate cancers (n = 20), hormone refractory prostate cancers (n = 19) and benign prostatic tissues (n = 38) were also analyzed.

RESULTS

In total, strong epithelial periostin expression was detectable in 142 of 418 (34.0%) of prostate carcinomas and in 11 of 38 benign prostate glands (28.9%). Increased periostin expression in carcinoma cells was significantly associated with high Gleason score (p < 0.01) and advanced tumour stage (p < 0.05) in the test cohort. Whereas periostin expression was weak or absent in the stroma around normal prostate glands, strong periostin expression in tumour stroma was found in most primary and metastatic prostate cancers. High stromal periostin expression was associated with higher Gleason scores (p < 0.001). There was a relationship between stromal periostin expression and shortened PSA relapse free survival times in the training cohort (p < 0.05).

CONCLUSIONS

Our data indicate that periostin up-regulation is related to increased tumour aggressiveness in prostate cancer and might be a promising target for therapeutical interventions in primary and metastatic prostate cancer.

Periostin, a cell adhesion molecule, facilitates invasion in the tumor microenvironment and annotates a novel tumor-invasive signature in esophageal cancer

Human squamous cell cancers are the most common epithelially derived malignancies. One example is esophageal squamous cell carcinoma (ESCC), which is associated with a high mortality rate that is related to a propensity for invasion and metastasis. Here, we report that periostin, a highly expressed cell adhesion molecule, is a key component of a novel tumor-invasive signature obtained from an organotypic culture model of engineered ESCC. This tumor-invasive signature classifies with human ESCC microarrays, underscoring its utility in human cancer. Genetic modulation of periostin promotes tumor cell migration and invasion as revealed in gain-of-loss and loss-of-function experiments. Inhibition of epidermal growth factor receptor signaling and restoration of wild-type p53 function were each found to attenuate periostin, suggesting the interdependence of two common genetic alterations with periostin function. Collectively, our studies reveal periostin as an important mediator of ESCC tumor invasion and they indicate that organotypic (three-dimensional) culture can offer an important tool to discover novel biological effectors in cancer.

Osteogenic differentiation capacity of porcine dental follicle progenitor cells

This study examined the effect of extracellular matrix (ECM) on the osteogenic differentiation capacity and osteogenesis of dental follicle cells. Single cell-derived porcine dental follicle cells (DFC-I) obtained at the early stage of crown formation in tooth were subcultured and characterized using periodontal ligament cells (PDLC) and bone marrow-derived mesenchymal stem cells (BMSC) as comparison cell populations. The effect of ECM constituents including collagen type I, fibronectin, laminin, and collagen type IV on the differentiation of DFC-1 into osteogenic-lineage cells was evaluated in vitro. In addition, the DFC-1, PDLC, and BMSC populations were compared for osteogenic capacity in vitro by Alizarin red staining and in vivo by transplantation. DFC-I showed different features from PDLC and BMSC. Different components of ECM had different effects on the differentiation of DFC-1 into osteogenic-lineage cells in vitro. Alkaline phosphatase activity and matrix mineralization as early- and late-stage markers of osteogenesis, respectively, supported the differentiation of DFC-1 into osteogenic-related cells in vitro. All three cell types showed equivalent osteogenic capacity in vivo at 4 weeks postoperatively. There were no statistically significant differences among the cell populations with respect to capacity for bone formation. These results suggest a potential application for dental follicle cells in bone-tissue engineering.

Metastatic outgrowth encompasses COL-I, FN1, and POSTN up-regulation and assembly to fibrillar networks regulating cell adhesion, migration, and growth

Although the outgrowth of micrometastases into macrometastases is the rate-limiting step in metastatic progression and the main determinant of cancer fatality, the molecular mechanisms involved have been little studied. Here, we compared the gene expression profiles of melanoma lymph node micro- and macrometastases and unexpectedly found no common up-regulation of any single growth factor/cytokine, except for the cytokine-like SPP1. Importantly, metastatic outgrowth was found to be consistently associated with activation of the transforming growth factor-beta signaling pathway (confirmed by phospho-SMAD2 staining) and concerted up-regulation of POSTN, FN1, COL-I, and VCAN genes-all inducible by transforming growth factor-beta. The encoded extracellular matrix proteins were found to together form intricate fibrillar networks around tumor cell nests in melanoma and breast cancer metastases from various organs. Functional analyses suggested that these newly synthesized protein networks regulate adhesion, migration, and growth of tumor cells, fibroblasts, and endothelial cells. POSTN acted as an anti-adhesive molecule counteracting the adhesive functions of FN1 and COL-I. Further, cellular FN and POSTN were specifically overexpressed in the newly forming/formed tumor blood vessels. Transforming growth factor-beta receptors and the metastasis-related matrix proteins, POSTN and FN1, in particular, may thus provide attractive targets for development of new therapies against disseminated melanoma, breast cancer, and possibly other tumors, by affecting key processes of metastasis: tumor/stromal cell migration, growth, and angiogenesis.

Spatiotemporal expression of periostin during skin development and incisional wound healing: lessons for human fibrotic scar formation

Differentiation of fibroblasts to myofibroblasts and collagen fibrillogenesis are two processes essential for normal cutaneous development and repair, but their misregulation also underlies skin-associated fibrosis. Periostin is a matricellular protein normally expressed in adult skin, but its role in skin organogenesis, incisional wound healing and skin pathology has yet to be investigated in any depth. Using C57/BL6 mouse skin as model, we first investigated periostin protein and mRNA spatiotemporal expression and distribution during development and after incisional wounding. Secondarily we assessed whether periostin is expressed in human skin pathologies, including keloid and hypertrophic scars, psoriasis and atopic dermatitis. During development, periostin is expressed in the dermis, basement membrane and hair follicles from embryonic through neonatal stages and in the dermis and hair follicle only in adult. In situ hybridization demonstrated that dermal fibroblasts and basal keratinocytes express periostin mRNA. After incisional wounding, periostin becomes re-expressed in the basement membrane within the dermal-epidermal junction at the wound edge re-establishing the embryonic deposition pattern present in the adult. Analysis of periostin expression in human pathologies demonstrated that it is over-expressed in keloid and hypertrophic scars, atopic dermatitis, but is largely absent from sites of inflammation and inflammatory conditions such as psoriasis. Furthermore, in vitro we demonstrated that periostin is a transforming growth factor beta 1 inducible gene in human dermal fibroblasts. We conclude that periostin is an important ECM component during development, in wound healing and is strongly associated with pathological skin remodeling.

SUMMARY

Periostin is a fibrogenic protein that mediates fibroblast differentiation and extracellular matrix synthesis. Here, we show that periostin is dynamically and temporally expressed during skin development, is induced by TGF-beta1 in vitro and is significantly upregulated during wound repair as well as cutaneous pathologies.

Lysophosphatidic acid-induced expression of periostin in stromal cells: Prognoistic relevance of periostin expression in epithelial ovarian cancer

Lysophosphatidic acid (LPA) is a bioactive lipid crucial for the initiation and progression of ovarian cancer. Identification of LPA-induced biomarkers is necessary for predicting prognosis of ovarian cancer patients. Here we report periostin, an extracellular matrix protein, as an LPA-induced protein in stromal cells and as a prognostic marker in patients with epithelial ovarian cancer (EOC). In human EOC tissues, periostin was mainly expressed in cancer-associated stromal fibroblasts, but not in cancer cells. The expression levels of periostin highly correlated with poor survival and tumor recurrence of ovarian cancer patients. Treatment of human adipose tissue-derived stromal cells with LPA or conditioned media from human ovarian adenocarcinoma cell lines, such as SK-OV-3 and OVCAR-3, induced expression of periostin. The periostin expression induced by cancer-conditioned media was abrogated by silencing of the LPA receptor 1 expression using small hairpin RNA lentivirus. Recombinant periostin stimulated adhesion and invasion of SK-OV-3 human ovarian adenocarcinoma cells and induced expression of matrix metalloprotease-2 in the cancer cells. These results suggest that LPA is associated with the expression of periostin in cancer-associated fibroblasts of EOC.

Overexpression of periostin and lumican in esophageal squamous cell carcinoma

To identify biomarkers for early detection for esophageal squamous cell carcinoma (ESCC), we previously carried out a genome-wide gene expression profiling study using an oligonucleotide microarray platform. This analysis led to identification of several transcripts that were significantly upregulated in ESCC compared to the adjacent normal epithelium. In the current study, we performed immunohistochemical analyses of protein products for two candidates genes identified from the DNA microarray analysis, periostin (POSTN) and lumican (LUM), using tissue microarrays. Increased expression of both periostin and lumican was observed in 100% of 137 different ESCC samples arrayed on tissue microarrays. Increased expression of periostin and lumican was observed in carcinoma as well as in stromal cell in the large majority of cases. These findings suggest that these candidates can be investigated in the sera of ESCC patients using ELISA or multiple reaction monitoring (MRM) type assays to further explore their utility as biomarkers.

Loading-related regulation of gene expression in bone in the contexts of estrogen deficiency, lack of estrogen receptor alpha and disuse

Loading-related changes in gene expression in resident cells in the tibia of female mice in the contexts of normality (WT), estrogen deficiency (WT-OVX), absence of estrogen receptor alpha (ERalpha(-/-)) and disuse due to sciatic neurectomy (WT-SN) were established by microarray. Total RNA was extracted from loaded and contra-lateral non-loaded tibiae at selected time points after a single, short period of dynamic loading sufficient to engender an osteogenic response. There were marked changes in the expression of many genes according to context as well as in response to loading within those contexts. In WT mice at 3, 8, 12 and 24 h after loading the expression of 642, 341, 171 and 24 genes, respectively, were differentially regulated compared with contra-lateral bones which were not loaded. Only a few of the genes differentially regulated by loading in the tibiae of WT mice have recognized roles in bone metabolism or have been linked previously to osteogenesis (Opn, Sost, Esr1, Tgfb1, Lrp1, Ostn, Timp, Mmp, Ctgf, Postn and Irs1, BMP and DLX5). The canonical pathways showing the greatest loading-related regulation were those involving pyruvate metabolism, mitochondrial dysfunction, calcium-induced apoptosis, glycolysis/gluconeogenesis, aryl hydrocarbon receptor and oxidative phosphorylation. In the tibiae from WT-OVX, ERalpha(-/-) and WT-SN mice, 440, 439 and 987 genes respectively were differentially regulated by context alone compared to WT. The early response to loading in tibiae of WT-OVX mice involved differential regulation compared to their contra-lateral non-loaded pair of fewer genes than in WT, more down-regulation than up-regulation and a later response. This was shared by WT-SN. In tibiae of ERalpha(-/-) mice, the number of genes differentially regulated by loading was markedly reduced at all time points. These data indicate that in resident bone cells, both basal and loading-related gene expression is substantially modified by context. Many of the genes differentially regulated by the earliest loading-related response were primarily involved in energy metabolism and were not specific to bone.

In vitro biocompatibility of poly(vinylidene fluoride-trifluoroethylene)/barium titanate composite using cultures of human periodontal ligament fibroblasts and keratinocytes

The aim of this work was to evaluate the biocompatibility of poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) membrane to be used in guided tissue regeneration (GTR). Fibroblasts from human periodontal ligament (hPDLF) and keratinocytes (SCC9) were plated on P(VDF-TrFE)/BT and polytetrafluorethylene membranes at a cell density of 20,000 cells well(-1) and cultured for up to 21 days. Cell morphology, adhesion and proliferation were evaluated in hPDLF and keratinocytes, while total protein content and alkaline phosphatase (ALP) activity were assayed only for hPDLF. Using a higher cell density, real-time polymerase chain reaction (PCR) was performed to assess the expression of typical genes of hPDLF, such as periostin, PDLs17, S100A4 and fibromodulin, and key phenotypic markers of keratinocytes, including involucrin, keratins 1, 10 and 14. Expression of the apoptotic genes bax, bcl-2 and survivin was evaluated for both cultures. hPDLF adhered and spread more on P(VDF-TrFE)/BT, whereas keratinocytes showed a round shape on both membranes. hPDLF adhesion was greater on P(VDF-TrFE)/BT at 2 and 4h, while keratinocyte adhesion was similar for both membranes. Whereas proliferation was significantly higher for hPDLF on P(VDF-TrFE)/BT at days 1 and 7, no signs of keratinocyte proliferation could be noticed for both membranes. Total protein content was greater on P(VDF-TrFE)/BT at 7, 14 and 21 days, and higher levels of ALP activity were observed on P(VDF-TrFE)/BT at 21 days. Real-time PCR revealed higher expression of phenotypic markers of hPDLF and keratinocytes as well as greater expression of apoptotic genes in cultures grown on P(VDF-TrFE)/BT. These results indicate that, by favoring hPDLF adhesion, spreading, proliferation and typical mRNA expression, P(VDF-TrFE)/BT membrane should be considered an advantageous alternative for GTR.

Interaction between periostin and BMP-1 promotes proteolytic activation of lysyl oxidase

Intra- and intermolecular covalent cross-linking between collagen fibrils, catalyzed by lysyl oxidase (LOX), determines the mechanical properties of connective tissues; however, mechanisms that regulate the collagen cross-linking according to tissue specificity are not well understood. Here we show that periostin, a secretory protein in the dense connective tissues, promotes the activation of LOX. Previous studies showed that periostin null mice exhibit reduced collagen cross-linking in their femurs, periosteum, infarcted myocardium, and tendons. Presently, we showed that active LOX protein, formed by cleavage of its propeptide by bone morphogenetic protein-1 (BMP-1), was decreased in calvarial osteoblast cells derived from periostin null mice. Overexpression of periostin promoted the proteolytic cleavage of the propeptide, which increased the amount of active LOX protein. The results of co-immunoprecipitation and solid phase binding assays revealed that periostin interacted with BMP-1. Furthermore, this interaction probably resulted in enhanced deposition of BMP-1 on the extracellular matrix, suggesting that this enhanced deposition would lead to cleavage of the propeptide of LOX. Thus, we demonstrated that periostin supported BMP-1-mediated proteolytic activation of LOX on the extracellular matrix, which promoted collagen cross-linking.

Periostin shows increased evolutionary plasticity in its alternatively spliced region

Background

Periostin (POSTN) is a secreted extracellular matrix protein of poorly defined function that has been related to bone and heart development as well as to cancer. In human and mouse, it is known to undergo alternative splicing in its C-terminal region, which is devoid of known protein domains. Differential expression of periostin, sometimes of specific splicing isoforms, is observed in a broad range of human cancers, including breast, pancreatic, and colon cancer. Here, we combine genomic and transcriptomic sequence data from vertebrate organisms to study the evolution of periostin and particularly of its C-terminal region.

Results

We found that the C-terminal part of periostin is markedly more variable among vertebrates than the rest of periostin in terms of exon count, length, and splicing pattern, which we interpret as a consequence of neofunctionalization after the split between periostin and its paralog transforming growth factor, beta-induced (TGFBI). We also defined periostin's sequential 13-amino acid repeat units - well conserved in teleost fish, but more obscure in higher vertebrates - whose secondary structure is predicted to be consecutive beta strands. We suggest that these beta strands may mediate binding interactions with other proteins through an extended beta-zipper in a manner similar to the way repeat units in bacterial cell wall proteins have been reported to bind human fibronectin.

Conclusions

Our results, obtained with the help of the increasingly large collection of complete vertebrate genomes, document the evolutionary plasticity of periostin's C-terminal region, and for the first time suggest a basis for its functional role.

Gene expression profiling of cholangiocarcinoma-derived fibroblast reveals alterations related to tumor progression and indicates periostin as a poor prognostic marker

Background

Fibroblasts play important roles in several cancers. It was hypothesized that cholangiocarcinoma (CCA)-associated fibroblasts (Cfs) differ from non-tumorigenic liver fibroblasts (Lfs) in their gene expression profiles resulting in the capability to promote cancer. Periostin (PN) is a multi-functional protein and has emerged as a promising marker for tumor progression. The role of PN in CCA, however, has not yet been explored.

Results

In this study, the gene expression profile of Cfs in comparison to Lfs was performed using oligonucleotide microarrays. The common- and unique-expressed genes in Cfs and the promising roles in cancer promotion and progression were determined. PN was markedly over-expressed in Cfs confirmed by real time RT-PCR and western blot analysis. Immunohistochemistry examination of a number of patients with intrahepatic CCA showed the expression of PN solely in stromal fibroblasts, but was expressed neither in cancer cells nor immune cells. Low to no expression of PN was observed in tissues of benign liver disease and hepatocellular carcinoma. CCA patients with high levels of PN had significantly shorter survival time than those with low levels (P = 0.026). Multivariate analysis revealed high levels of PN (P = 0.045) and presence of lymph node metastasis (P = 0.002) as independent poor prognostic factors. The in vitro study revealed that recombinant PN induced CCA cell proliferation and invasion. Interestingly, interference RNA against integrin α₅ significantly reduced the cellular response to PN-stimulated proliferation and invasion.

Conclusion

The gene expression profile of fibroblasts in CCA is apparently explored for the first time and has determined the genes involving in induction of this cancer progression. High PN can be used to distinguish CCA from other related liver diseases and is proposed as a prognostic factor of poor survival. Regulation of fibroblast-derived PN in CCA proliferation and invasion may be considered as an alternative therapeutic approach.

Gene expression profiling of cholangiocarcinoma-derived fibroblast reveals alterations related to tumor progression and indicates periostin as a poor prognostic marker

BACKGROUND

Fibroblasts play important roles in several cancers. It was hypothesized that cholangiocarcinoma (CCA)-associated fibroblasts (Cfs) differ from non-tumorigenic liver fibroblasts (Lfs) in their gene expression profiles resulting in the capability to promote cancer. Periostin (PN) is a multi-functional protein and has emerged as a promising marker for tumor progression. The role of PN in CCA, however, has not yet been explored.

RESULTS

In this study, the gene expression profile of Cfs in comparison to Lfs was performed using oligonucleotide microarrays. The common- and unique-expressed genes in Cfs and the promising roles in cancer promotion and progression were determined. PN was markedly over-expressed in Cfs confirmed by real time RT-PCR and western blot analysis. Immunohistochemistry examination of a number of patients with intrahepatic CCA showed the expression of PN solely in stromal fibroblasts, but was expressed neither in cancer cells nor immune cells. Low to no expression of PN was observed in tissues of benign liver disease and hepatocellular carcinoma. CCA patients with high levels of PN had significantly shorter survival time than those with low levels (P = 0.026). Multivariate analysis revealed high levels of PN (P = 0.045) and presence of lymph node metastasis (P = 0.002) as independent poor prognostic factors. The in vitro study revealed that recombinant PN induced CCA cell proliferation and invasion. Interestingly, interference RNA against integrin alpha 5 significantly reduced the cellular response to PN-stimulated proliferation and invasion.

CONCLUSION

The gene expression profile of fibroblasts in CCA is apparently explored for the first time and has determined the genes involving in induction of this cancer progression. High PN can be used to distinguish CCA from other related liver diseases and is proposed as a prognostic factor of poor survival. Regulation of fibroblast-derived PN in CCA proliferation and invasion may be considered as an alternative therapeutic approach.

The matricellular protein periostin is required for sost inhibition and the anabolic response to mechanical loading and physical activity

Periostin (gene Postn) is a secreted extracellular matrix protein involved in cell recruitment and adhesion and plays an important role in odontogenesis. In bone, periostin is preferentially expressed in the periosteum, but its functional significance remains unclear. We investigated Postn(-/-) mice and their wild type littermates to elucidate the role of periostin in the skeletal response to moderate physical activity and direct axial compression of the tibia. Furthermore, we administered a sclerostin-blocking antibody to these mice in order to demonstrate the influence of sustained Sost expression in their altered bone phenotypes. Cancellous and cortical bone microarchitecture as well as bending strength were altered in Postn(-/-) compared with Postn(+/+) mice. Exercise and axial compression both significantly increased bone mineral density and trabecular and cortical microarchitecture as well as biomechanical properties of the long bones in Postn(+/+) mice by increasing the bone formation activity, particularly at the periosteum. These changes correlated with an increase of periostin expression and a consecutive decrease of Sost in the stimulated bones. In contrast, mechanical stimuli had no effect on the skeletal properties of Postn(-/-) mice, where base-line expression of Sost levels were higher than Postn(+/+) and remained unchanged following axial compression. In turn, the concomitant injection of sclerostin-blocking antibody rescued the bone biomechanical response in Postn(-/-) mice. Taken together, these results indicate that the matricellular periostin protein is required for Sost inhibition and thereby plays an important role in the determination of bone mass and microstructural in response to loading.

Origin of cardiac fibroblasts and the role of periostin

Cardiac fibroblasts are the most populous nonmyocyte cell type within the mature heart and are required for extracellular matrix synthesis and deposition, generation of the cardiac skeleton, and to electrically insulate the atria from the ventricles. Significantly, cardiac fibroblasts have also been shown to play an important role in cardiomyocyte growth and expansion of the ventricular chambers during heart development. Although there are currently no cardiac fibroblast-restricted molecular markers, it is generally envisaged that the majority of the cardiac fibroblasts are derived from the proepicardium via epithelial-to-mesenchymal transformation. However, still relatively little is known about when and where the cardiac fibroblasts cells are generated, the lineage of each cell, and how cardiac fibroblasts move to reside in their final position throughout all four cardiac chambers. In this review, we summarize the present understanding regarding the function of Periostin, a useful marker of the noncardiomyocyte lineages, and its role during cardiac morphogenesis. Characterization of the cardiac fibroblast lineage and identification of the signals that maintain, expand and regulate their differentiation will be required to improve our understanding of cardiac function in both normal and pathophysiological states.

Incorporation of tenascin-C into the extracellular matrix by periostin underlies an extracellular meshwork architecture

Extracellular matrix (ECM) underlies a complicated multicellular architecture that is subjected to significant forces from mechanical environment. Although various components of the ECM have been enumerated, mechanisms that evolve the sophisticated ECM architecture remain to be addressed. Here we show that periostin, a matricellular protein, promotes incorporation of tenascin-C into the ECM and organizes a meshwork architecture of the ECM. We found that both periostin null mice and tenascin-C null mice exhibited a similar phenotype, confined tibial periostitis, which possibly corresponds to medial tibial stress syndrome in human sports injuries. Periostin possessed adjacent domains that bind to tenascin-C and the other ECM protein: fibronectin and type I collagen, respectively. These adjacent domains functioned as a bridge between tenascin-C and the ECM, which increased deposition of tenascin-C on the ECM. The deposition of hexabrachions of tenascin-C may stabilize bifurcations of the ECM fibrils, which is integrated into the extracellular meshwork architecture. This study suggests a role for periostin in adaptation of the ECM architecture in the mechanical environment.

The proteomic analysis of human neonatal umbilical cord serum by mass spectrometry

AIM

To investigate the proteome composition and function of human neonatal arterial umbilical cord.

METHODS

Serum proteomic analyses were performed on samples from both males and females by using a combination of techniques: (1) removal of six high-abundance proteins, (2) tryptic digestion of low-abundance proteins, (3) separation of peptide mixtures by reverse-phase high-performance liquid chromatography (RP-HPLC), and (4) peptide identification using electrospray ionization tandem mass spectrometry (ESI-MS/MS).

RESULTS

A total of 837 non-redundant proteins were identified, with 213 male-specific and 239 female-specific proteins. Among them, 319 proteins were identified by at least 2 distinct peptides. The subcellular localization, function, and pathway involvement for each of the identified proteins were analyzed. A comparison of this neonatal proteome to that of adult serum proteome revealed novel biomarkers, such as alpha-fetoprotein and periostin that were specific to newborn infants.

CONCLUSION

These data will contribute to a better understanding of the composition of umbilical cord serum and aid the discovery of novel biomarkers for the prenatal diagnosis of fetal abnormalities.

The many facets of the matricelluar protein periostin during cardiac development, remodeling, and pathophysiology

Periostin is a member of a growing family of matricellular proteins, defined by their ability to interact with components of the extracellular milieu, and with receptors at the cell surface. Through these interactions, periostin has been shown to play a crucial role as a profibrogenic molecule during tissue morphogenesis. Tissues destined to become fibrous structures are dependent on cooperative interactions between periostin and its binding partners, whereas in its absence, these structures either totally or partially fail to become mature fibrous entities. Within the heart, fibrogenic differentiation is required for normal tissue maturation, remodeling and function, as well as in response to a pathological myocardial insult. In this review, aspects related to the function of periostin during cardiac morphogenesis, remodeling and pathology are summarized.

Identification of differentially expressed genes between osteoblasts and osteocytes

Osteocytes represent the most abundant cellular component of mammalian bones with important functions in bone mass maintenance and remodeling. To elucidate the differential gene expression between osteoblasts and osteocytes we completed a comprehensive analysis of their gene profiles. Selective identification of these two mature populations was achieved by utilization of visual markers of bone lineage cells. We have utilized dual GFP reporter mice in which osteocytes are expressing GFP (topaz) directed by the DMP1 promoter, while osteoblasts are identified by expression of GFP (cyan) driven by 2.3 kb of the Col1a1 promoter. Histological analysis of 7-day-old neonatal calvaria confirmed the expression pattern of DMP1GFP in osteocytes and Col2.3 in osteoblasts and osteocytes. To isolate distinct populations of cells we utilized fluorescent activated cell sorting (FACS). Cell suspensions were subjected to RNA extraction, in vitro transcription and labeling of cDNA and gene expression was analyzed using the Illumina WG-6v1 BeadChip. Following normalization of raw data from four biological replicates, 3444 genes were called present in all three sorted cell populations: GFP negative, Col2.3cyan(+) (osteoblasts), and DMP1topaz(+) (preosteocytes and osteocytes). We present the genes that showed in excess of a 2-fold change for gene expression between DMP1topaz(+) and Col2.3cyan(+) cells. The selected genes were classified and grouped according to their associated gene ontology terms. Genes clustered to osteogenesis and skeletal development such as Bmp4, Bmp8a, Dmp1, Enpp1, Phex and Ank were highly expressed in DMP1topaz(+)cells. Most of the genes encoding extracellular matrix components and secreted proteins had lower expression in DMP1topaz(+) cells, while most of the genes encoding plasma membrane proteins were increased. Interestingly a large number of genes associated with muscle development and function and with neuronal phenotype were increased in DMP1topaz(+) cells, indicating some new aspects of osteocyte biology. Although a large number of genes differentially expressed in DMP1topaz(+) and Col2.3cyan(+) cells in our study have already been assigned to bone development and physiology, for most of them we still lack any substantial data. Therefore, isolation of osteocyte and osteoblast cell populations and their subsequent microarray analysis allowed us to identify a number or genes and pathways with potential roles in regulation of bone mass.

The increased expression of periostin during early stages of prostate cancer and advanced stages of cancer stroma

BACKGROUND

Three-dimensional culture (3DC) is a relevant in vitro model used to study prostate development and carcinogenesis. Recent studies have indicated that 3DC-associated genes would be more sensitive as prognostic markers for cancer; however, no 3DC-associated genes in prostate cancer (CaP) have thus far been elucidated.

METHODS

Candidate 3DC-associated genes in non-malignant prostatic epithelial cells, RWPE-1 and TA2, were selected, based on a comparison of microarray gene expression data between cells grown in two-dimensional culture (2DC) and in 3DC. To extract CaP-associated genes among the 3DC-associated genes, gene expression levels from the microdissected tissue samples were compared between 20 well-differentiated or 20 poorly differentiated CaP, as well as matched normal prostate epithelium. The expression levels of CaP-associated genes in 3DC were validated by quantitative RT-PCR using TA2 cells in 2DC and 3DC. Protein expression of periostin (POSTN), which is one of the 3DC CaP-associated genes, was further evaluated in the clinical samples by immunohistochemistry.

RESULTS

Several genes including POSTN were identified as CaP-associated genes using a 3DC system. Immunohistochemical analyses revealed that POSTN expression was increased in the early stages of CaP (Gleason score 6-7), but not in the advanced stages of CaP. Furthermore, the positive ratio observed for the expression of POSTN in tumor-associated stroma was significantly correlated with the degree of malignancy.

CONCLUSIONS

POSTN, one of the 3DC-associated genes, may serve as a potential biomarker for predicting the pathological grade and prognosis of CaP. Prostate 69: 1398-1403, 2009. (c) 2009 Wiley-Liss, Inc.

Lack of periostin leads to suppression of Notch1 signaling and calcific aortic valve disease

The Postn gene encodes protein periostin. During embryonic development, it is highly expressed in the outflow tract (OFT) endocardial cushions of the developing heart, which give rise to several structures of the mature heart including the aortic valve. Periostin was previously implicated in osteoblast differentiation, cancer metastasis, and tooth and bone development, but its role in cardiac OFT development is unclear. To elucidate the role that periostin plays in the developing heart we analyzed cardiac OFT phenotype in mice after deletion of the Postn gene. We found that lack of periostin in the embryonic OFT leads to ectopic expression of the proosteogenic growth factor pleiotrophin (Ptn) and overexpression of delta-like 1 homolog (Dlk1), a negative regulator of Notch1, in the distal (prevalvular) cushions of the OFT. This resulted in suppression of Notch1 signaling, strong induction of the central transcriptional regulator of osteoblast cell fate Runx2, upregulation of osteopontin and osteocalcin expression, and subsequent calcification of the aortic valve. Our data suggest that periostin represses a default osteogenic program in the OFT cushion mesenchyme and promotes differentiation along a fibrogenic lineage. Lack of periostin causes derepression of the osteogenic potential of OFT mesenchymal cells, calcium deposition, and calcific aortic valve disease. These results establish periostin as a key regulator of OFT endocardial cushion mesenchymal cell fate during embryonic development.

Identification and characterization of a novel CXC chemokine in xenograft tumor induced by mas-overexpressing cells

Overexpressions of G protein-coupled receptor (GPCR) with elevated downstream signaling events have been reported in various tumors. However, the cellular mechanism that GPCR overexpression leads to tumor formation is largely unknown. The orphan GPCR mas was originally isolated from a human epidermoid carcinoma. In vivo studies of mas-overexpressing cells suggested that xenograft tumor formation was positively correlated with the levels of mas expression. Histochemical analysis indicated that xenograft tumor consisted of mas-transfected and stromal cells. Biochemical analyses revealed that cells overexpressing mas exhibited significantly increased anchorage-independent growth, whereas there was no significant difference in cell proliferation in comparison with empty vector-transfected control cells. Expression profiling using mRNA differential display and Northern analysis indicated an elevated expression of GRO and a novel CXC chemokines, tumor-induced factor (TIF), in mas-transfected cells and xenograft tumor. Bacterially expressed recombinant TIF was found to act as a neutrophil chemoattractant in a chemotactic assay. These results suggest that mas overexpression enables anchorage-independent growth of transformed cells, and interplays of secreted chemokines with stromal cells modulate xenograft tumor formation. Importantly, a novel CXC chemokine, TIF, was identified in the xenograft tumor tissues.

Expression of periostin in the serum of NSCLC and its function on proliferation and migration of human lung adenocarcinoma cell line (A549) in vitro

Periostin is over expressed in many epithelial malignant cancers, including lung cancer, breast cancer, ovarian cancer and colon cancer. It is related with the progression and migration of breast and ovarian cancer cells in vitro. The aim of this study was to investigate the serum level of periostin in non-small cell lung cancer (NSCLC) and its relationship with established biological and prognostic factors by enzyme-linked-immunosorbent serologic assay. We also observe the function of periostin on the proliferation and migration of human lung adenocarcinoma cell line (A549) and discuss the mechanism. The mean value for serum periostin (POSTN) was elevated in NSCLC patients (242.84 + or - 5.33 pg/ml) compared to the normal healthy volunteers (215.66 + or - 11.67 pg/ml) (p = 0.030). The serum level of periostin of NSCLC patients had no connection with gender, age, pathological type, TNM stage, lymph node status, tumor size and invasiveness. We constructed a plasmid named pEGFP-N1/POSTN expressing full-length human periostin. Transfecting the plasmid to A549 cells and periostin was efficiently expressed in transfected A549 cells. Our data showed that periostin could promote the proliferation and migration of A549 cells by inducing vimentin and N-cadherin expression and downregulating E-cadherin expression. These results strongly suggest that periostin is a novel molecular which play an important role during the progression and development of NSCLC.

Periostin mediates vascular smooth muscle cell migration through the integrins alphavbeta3 and alphavbeta5 and focal adhesion kinase (FAK) pathway

Smooth muscle cell (SMC) migration involves interactions of integrin receptors with extracellular matrix (ECM) and is an important process of neointimal formation in atherosclerosis and restenosis after vascular interventions. Previous studies have shown that periostin (PN), a novel ECM protein, is upregulated in rat carotid artery after balloon injury, and growth factor-stimulated expression of PN promotes SMC migration in vitro. Here, we address the mechanism by which PN-integrin interaction mediates SMC migration in vitro. Aortic SMCs isolated from PN null mice exhibited a significantly reduced ability to migrate and proliferate in vitro. Endogenous PN protein was absent and very low in the culture medium from the primary cultures of PN-/- and wildtype SMCs, respectively. In both types of SMCs, adenovirus-mediated overexpression of HA-tagged PN to a similar extent, which induced a robust cell migration concomitantly with an increase in beta3-integrin expression and phosphorylation of FAK (Tyr397). Furthermore, in cultured human SMCs, specific integrin blocking antibodies showed that interactions of PN-alphanubeta3 and PN-alphanubeta5, but not PN-beta1 integrins, are required for SMC migration. Inhibition of FAK signaling by overexpression of an endogenous FAK inhibitor termed FRNK (FAK-related nonkinase) significantly attenuated FAK (Tyr397) phosphorylation and the SMC migration induced by PN. These results reveal a mechanism whereby PN mediates vascular SMC migration through an interaction with alphaV-integrins (mainly alphanubeta3) and subsequent activation of FAK pathway.

The KK-Periome database for transcripts of periodontal ligament development

The periodontal ligament (PDL) is a strong connective tissue that surrounds the tooth root, absorbs occlusal forces, and functions as a sense organ. PDL originated from dental follicle (DF), which possessed mesenchymal progenitors in the developing tooth germ. However, as specific marker genes for PDL and DF are currently unavailable, the molecular mechanisms of PDL development are yet to be clarified. To facilitate the identification of such genes, we have previously established a transcriptome database of the human PDL (the KK-Periome database) and screened for specific genes expressed during PDL development. Initial screening of the database revealed two marker genes for distinguishing DF and PDL. The KK-Periome database thus appears to offer a useful resource for investigating genes involved in PDL development.

Identification of secreted proteins associated with obesity and type 2 diabetes in Psammomys obesus

OBJECTIVE

Skeletal muscle produces a variety of secreted proteins that have important roles in intercellular communication and affects processes such as glucose homoeostasis. The objective of this study was to develop a novel Signal Sequence Trap (SST) in conjunction with cDNA microarray technology to identify proteins secreted from skeletal muscle of Psammomys obesus that were associated with obesity and type 2 diabetes (T2D).

DESIGN

Secreted proteins that were differentially expressed between lean, normal glucose tolerant (NGT), overweight and impaired glucose tolerant (IGT) and obese, T2D P. obesus were isolated using SST in conjunction with cDNA microarray technology. Subsequent gene expression was measured in tissues from P. obesus by real-time PCR (RT-PCR).

RESULTS

The SST yielded 1600 positive clones, which were screened for differential expression. A total of 91 (approximately 6%) clones were identified by microarray to be differentially expressed between NGT, IGT and T2D P. obesus. These clones were sequenced to identify 51 genes, of which only 27 were previously known to encode secreted proteins. Three candidate genes not previously associated with obesity or type 2 diabetes, sushi domain containing 2, collagen and calcium-binding EGF domains 1 and periostin (Postn), as well as one gene known to be associated, complement component 1, were shown by RT-PCR to be differentially expressed in skeletal muscle of P. obesus. Further characterization of the secreted protein Postn revealed it to be predominantly expressed in adipose tissue, with higher expression in visceral compared with subcutaneous adipose depots.

CONCLUSION

SST in conjunction with cDNA microarray technology is a powerful tool to identify differentially expressed secreted proteins involved in complex diseases such as obesity and type 2 diabetes. Furthermore, a number of candidate genes were identified, in particular, Postn, which may have a role in the development of obesity and type 2 diabetes.