Overexpression Of Periostin Research Articles

Abstract 056: The Impact of Periostin as A Regulator of Cardiac Remodeling

Background: Periostin (PN) is a matricellular protein that is induced by mechanostress and regulates organ remodeling. We previously documented that over-expression of full-length periostin (periostin1:Pn1) resulted in ventricular dilation with enhanced interstitial collagen deposition. Controversially, supplement of PN splicing variant lacking exon 17 (periostin2:Pn2) was reported to accelerate cardiac repair with the induction of cardiomyocyte proliferation and angiogenesis. The aim of this study was to investigate the different roles of PN splicing isoforms in cardiac remodeling. Methods: Coronary ligation was employed to induce cardiac remodeling in rat. A neutralizing antibody against exon17 (Pn1Ab) was injected intravenously every 6 days until day 21. Mice were followed ultrasonographically and then euthanized for histological analysis at day 56. In vitro study, the effect of each PN splicing isoform was assessed in rat cardiac fibroblast and HUVEC. Results: Administration of Pn1Ab resulted in 24.1 % decrease in infarct size and 38.2 % decrease in fibrotic area at day 56 post-operation (n=21, P<0.05). Consistently, echocardiography demonstrated 26.3 % better ejection fraction (P<0.05). Inhibition of fibrosis was associated with suppressed fibrosis-related gene expression such as collagen I, collagen III and TGF-beta1. Importantly, the number of myofibroblasts was significantly reduced in the Pn1Ab group, while neither cardiomyocyte proliferation nor angiogenesis was detected. In vitro study, Pn2 administration for HUVEC induced proliferation and tube formation however Pn1 did not. Pn1 administration accelerated maturation of myofibroblast more than Pn2. Conclusions: Pn1Ab preserved cardiac function through anti-fibrotic effect without cardiomyocyte proliferation and angiogenesis. Specific blockade of Pn1 without Pn2 will potentially lead to new therapeutic targets on a molecular basis to limit cardiac remodeling.

Upregulation of periostin prevents P53-mediated apoptosis in SGC-7901 gastric cancer cells

Periostin is frequently upregulated in human cancers including gastric cancer and implicated in cancer cell proliferation, invasion, and epithelial-mesenchymal transition. This study was undertaken to investigate the effects of periostin overexpression on the chemosensitivity of gastric cancer cells. We constructed a stable cell line overexpressing periostin in SGC-7901 human gastric cancer cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that periostin had no influence on the proliferation of SGC-7901 cells. Compared to empty vector-transfected cells, overexpression of periostin rendered SGC-7901 cells more resistant to cisplatin or 5-fluorouracil (5-FU)-induced apoptosis, accompanying with less release of cytochrome c from mitochondria and diminished cleavage of caspase-3 and poly (ADP-ribose) polymerase. Periostin-overexpressing cells treated with cisplatin or 5-FU showed significantly (p<0.05) decreased expression of Bax and p53 proteins and increased expression of Bcl-2 protein, when compared to drug-treated mock counterparts. Restoration of p53 expression by delivering wild-type p53 gene resulted in a marked increase in drug-induced apoptosis in periostin-overexpressing SGC-7901 cells. Periostin overexpression elevated the phosphorylation of Akt. Pretreatment of periostin-overexpressing cells with an Akt inhibitor, MK-2206, partially rescued periostin-mediated inhibition of p53 expression and drug resistance. Taken together, our data indicate that periostin confers protection against cisplatin or 5-FU-induced apoptosis in SGC-7901 cells, likely through modulating the Akt/p53 pathway, and thus represents a potential therapeutic target in gastric cancer.

Periostin, a stroma-associated protein, correlates with tumor invasiveness and progression in nasopharyngeal carcinoma

Recently, the tumor microenvironment is increasingly recognized as playing an important role in cancer proliferation, invasion, and metastasis. To screen stroma-associated proteins involved in nasopharyngeal carcinoma (NPC) carcinogenesis, laser capture microdissection (LCM) and quantitative proteomic analysis were employed to assess different protein expression of the stroma between NPC and normal nasopharyngeal mucosa (NNM). In this study, periostin was identified to be significantly up-regulated in NPC stroma compared with NNM stroma and the result was further confirmed by Western blotting. Immunohistochemistry showed that over-expression of periostin was frequently observed in the stroma of NPC and matched lymph node metastases (LNM) compared with the stroma of NNM. Statistical analysis showed over-expression of periostin was significantly associated with advanced clinical stage (P<0.001) and lymph node metastasis (P<0.001) and decreased overall survival (P<0.001) in NPC. Cox regression analysis indicated over-expression of periostin was an independent prognostic factor. Furthermore, ectopic expression of periostin was used to examine its effect on invasiveness of NPC cell in vitro and the result showed that periostin was able to promote invasiveness of NPC cell. In conclusion, periostin expression is correlated with tumor stage, lymph node metastasis, and patient survival. Periostin is a potential biomarker for the differentiation and prognosis of NPC, and it might play an important role in the progression of NPC.

Circulating Periostin Is Elevated in Patients with Multiple Myeloma and Correlates with Advanced Disease Features and High Bone Resorption,

Abstract 3922Periostin (previously called osteoblast-specific factor-2) is a disulfide-linked cell adhesion protein that belongs to the fasciclin family and is mainly produced by mesenchymal cells. Periostin is highly expressed in early osteoblastic cells and in the periosteum, where it acts as a regulator of bone remodeling. Recent clinical evidence suggests that periostin stimulates metastatic growth by promoting cancer cell survival, invasion and angiogenesis in several cancers. Especially, bone metastases from breast cancer induce overexpression of periostin by surrounding stromal cells and serum levels of periostin are elevated in such patients. However, there is no information on the role of periostin in multiple myeloma (MM). The aim of the study was to evaluate circulating periostin in a large number of MM patients and explore possible correlations with clinical and laboratory data, including stage and lytic bone disease.We studied 198 MM patients (106M/92F, median age 73 years) at different phases of their disease. Thirty three patients had smoldering myeloma (SMM) at diagnosis, 105 symptomatic MM at diagnosis, 30 patients were at a plateau phase and 30 patients had relapsed MM after previous response to therapy. For newly-diagnosed and relapsed patients, serum was stored at the time of diagnosis or relapse, while for patients at the plateau phase of the disease serum was collected at the time of confirmation of the plateau (at least 6 months with stable M-protein without criteria confirming progression). Serum periostin was measured using ELISA methodology in all patients along with a series of markers of bone remodeling that were measured in symptomatic MM patients at diagnosis: i) osteoclast regulators: sRANKL and osteoprotegerin (OPG); ii) osteoblast inhibitor dickkopf-1 (Dkk-1); iii) bone resorption markers: C-telopeptide of collagen type-I (CTX) and tartrate-resistant acid phosphatase isoform-5b (TRACP-5b); and iv) bone formation markers: bone-specific alkaline phosphatase (bALP) and osteocalcin. Evidence of bone involvement was documented using plain radiographs. Periostin was also measured in 23 patients with MGUS and in 30, gender- and age-matched, healthy controls.The circulating periostin concentrations of symptomatic MM patients at diagnosis (mean±SD: 911±694 ng/ml) were increased compared to controls (537±190 ng/ml; p<0.001), to SMM patients at diagnosis (601±351 ng/ml; p=0.001) and to MGUS patients (633±271 ng/ml; p =0.002). There was no significant difference regarding circulating periostin levels between SMM patients, MGUS patients and controls. Patients with MM at plateau phase had a borderline reduction of serum periostin concentrations (729±360 ng/ml) compared to symptomatic MM patients at diagnosis (p=0.05) but they continued to have increased levels compared to controls (p=0.013) and no difference compared to SMM and MGUS patients. Patients with relapsed MM had increased circulating periostin (938±847 ng/ml) compared to controls (p=0.016), MGUS (p=0.04) and SMM patients (p=0.04) but no significant difference compared to symptomatic patients at diagnosis. In symptomatic MM patients at diagnosis, serum periostin strongly correlated with beta2-microglobulin (r=0.384, p=0.004), LDH (r=0.428, p=0.001), and ISS stage [mean±SD of periostin values for ISS-1, ISS-2 and ISS-3 were: 542±196 ng/mL, 775±500 ng/mL and 1036±801 ng/mL, respectively; p=0.01]. High circulating periostin also correlated with increased bone resorption, as assessed by CTX levels (r=0.369, p=0.005) in symptomatic patients at diagnosis. Furthermore, patients with extensive lytic bone disease (>3 lytic lesions and/or a pathological fracture) had increased periostin levels compared to all others (p=0.01).Our results suggest that circulating periostin is elevated in patients with symptomatic and relapsed myeloma and correlated with advanced disease features including ISS stage and high LDH. The increased levels of periostin observed in patients with advanced bone disease and its strong correlation with the bone resorption marker CTX suggest that periostin may be implicated in the biology of myeloma-related bone disease. The confirmation of periostin upregulation in myeloma patients, even at the plateau phase of the disease, may reveal periostin as a promising target of therapeutic intervention for MM in the future. Disclosures:No relevant conflicts of interest to declare.

Periostin: a promising target of therapeutical intervention for prostate cancer

BackgroundIn our recent study, Periostin was up-regulated in prostate cancer(PCa) compared with benign prostate hyperplasia (BPH) by proteomics analysis of prostate biopsies. We investigated the effect of sliencing Periostin by RNA interference (RNAi) on the proliferation and migration of PCa LNCap cell line.MethodsAll the prostate biopsies from PCa, BPH and BPH with local prostatic intraepithelial neoplasm(PIN) were analyzed by iTRAQ(Isobaric tags for relative and absolute quantification) technology. Western blotting and immunohistochemical staining were used to verify Periostin expression in the tissues of PCa. Periostin expression in different PCa cell lines was determined by immunofluorescence staining, western blotting and reverse transcription PCR(RT-PCR). The LNCap cells with Periostin expression were used for transfecting shRNA-Periostin lentiviral particles. The efficancy of transfecting shRNA lentiviral particles was evaluated by immunofluorescence, western blotting and Real-time PCR. The effect of silencing Periostin expression by RNAi on proliferation of LNCap cells was determined by MTT assay and tumor xenografts. The tissue slices from theses xenografts were analyzed by hematoxylin and eosin(HE) staining. The expression of Periostin in the xenografts was deteminned by Immunohistochemical staining and western blotting. The migration of LNCap cells after silencing Periostin gene expression were analyzed in vitro.ResultsPeriostin as the protein of interest was shown 9.12 fold up-regulation in PCa compared with BPH. The overexpression of Periostin in the stroma of PCa was confirmed by western blotting and immunohistochemical staining. Periostin was only expressed in PCa LNCap cell line. Our results indicated that the transfection ratio was more than 90%. As was expected, both the protein level and mRNA level of Periostin in the stably expressing shRNA-Periostin LNCap cells were significantly reduced. The stably expressing shRNA-Periostin LNCap cells growed slowly in vitro and in vivo. The tissues of xenografts as PCa were verificated by HE staining. Additionally, the weak positive Periostin expressed tumor cells could be seen in the tissues of 6 xenografts from the group of down-regulated Periostin LNCap cells which had a significant decrease of the amount of Periostin compared to the other two group. Furthermore, our results demonstrated that sliencing Periostin could inhibit migration of LNCap cells in vitro.ConclusionsOur data indicates that Periostin as an up-regulated protein in PCa may be a promising target of therapeutical intervention for PCa in future.

Periostin identified as a potential biomarker of prostate cancer by iTRAQ-proteomics analysis of prostate biopsy

BackgroundProteomics may help us better understand the changes of multiple proteins involved in oncogenesis and progression of prostate cancer(PCa) and identify more diagnostic and prognostic biomarkers. The aim of this study was to screen biomarkers of PCa by the proteomics analysis using isobaric tags for relative and absolute quantification(iTRAQ).MethodsThe patients undergoing prostate biopsies were classified into 3 groups according to pathological results: benign prostate hyperplasia (BPH, n = 20), PCa(n = 20) and BPH with local prostatic intraepithelial neoplasm(PIN, n = 10). Then, all the specimens from these patients were analyzed by iTRAQ and two-dimensional liquid chromatography-tandem mass spectrometry (2DLC-MS/MS). The Gene Ontology(GO) function and the transcription regulation networks of the differentially expressed were analyzed by MetaCore software. Western blotting and Immunohistochemical staining were used to analyze the interesting proteins.ResultA total of 760 proteins were identified from 13787 distinct peptides, including two common proteins that enjoy clinical application: prostate specific antigen (PSA) and prostatic acid phosphatase(PAP). Proteins that expressed differentially between PCa and BPH group were further analyzed. Compared with BPH, 20 proteins were significantly differentially up-regulated (>1.5-fold) while 26 were significantly down-regulated in PCa(<0.66-fold). In term of GO database, the differentially expressed proteins were divided into 3 categories: cellular component(CC), molecular function (MF) and biological process(BP). The top 5 transcription regulation networks of the differentially expressed proteins were initiated through activation of SP1, p53, YY1, androgen receptor(AR) and c-Myc The overexpression of periostin in PCa was verified by western blotting and immunohistochemical staining.ConclusionOur study indicates that the iTRAQ technology is a new strategy for global proteomics analysis of the tissues of PCa. A significant up-regulation of periostin in PCa compared to BPH may provide clues for not only a promising biomarker for the prognosis of PCa but also a potential target for therapeutical intervention.

Periostin, a matrix specific protein, is associated with proliferation and invasion of pancreatic cancer

Overexpression of periostin is present in various malignant tumors and correlates with disease progression. However, its clinicopathological significance in pancreatic cancer is currently not known. Expression of periostin was analyzed by RT-PCR and western blotting in pancreatic cancers and cell lines. Using immunohistochemistry, expression of periostin in pancreatic cancers was evaluated according to factors influencing overall survival with Kaplan-Meier analysis. Ectopic expression of periostin was used to examine the effects of periostin on proliferation and invasiveness of pancreatic cancer cells in vitro. There was no detectable periostin mRNA and protein expression in the 4 pancreatic cell lines. Expression of periostin was found to be up-regulated in pancreatic cancer compared to the adjacent tumor free (TF) tissues by western blotting. The positive ratio of periostin expression in the neoplastic stroma was significantly correlated with the depth of invasion (p=0.007) and lymph node metastasis (p=0.027). Survival analysis showed that stromal or epithelium expression of periostin was associated with poor survival (p=0.035, p=0.022, log-rank test, respectively). In vitro studies showed that periostin was able to promote proliferation and invasiveness of pancreatic cancer cells. These results suggest that periostin may be involved in the progression and invasion of pancreatic 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.

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.

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.

Mechanical loading promotes Lewis lung cancer cell growth through periostin

Mechanical loading is known to trigger proliferation of tumor cells. Periostin is a new molecule found to increase in many cancers. To determine how mechanical strain modulates tumor growth and its possible mediation by periostin through TGF-beta1, Lewis lung cancer cells were cultured on flexible-bottomed culture plates and cyclically strained using Flexercell Strain Unit. Real-time RT-PCR was used to quantify periostin and TGF-beta1 mRNA levels at 6, 12, 18, and 24 h of loading. In addition, periostin and TGF-beta1 neutralizing antibodies were added to the medium. We showed that the proliferative ability of Lewis cancer cells was significantly increased by cyclical strain. This change can be blocked by 5 microg/ml of periostin neutralizing antibody. Periostin mRNA increased by 1.1-, 3.2-, 4.7-, and 9.2-fold while TGF-beta1 mRNA increased by 5.3-, 10.3-, 7.1-, and 6.5-fold at 6, 12, 18, and 24 h, respectively. Periostin protein in medium increased after cyclical strain. Expression of periostin mRNA in response to mechanical loading was completely blocked by 2.5 microg/ml of TGF-beta1 neutralizing antibody. In addition, overexpression of periostin in Lewis cells can promote cell proliferation. Our results suggest that periostin is a potent positive regulator of tumor growth in response to mechanical loading and is possibly a downstream factor of TGF-beta1.

A panel of biomarkers for esophageal squamous cell carcinoma

We have carried out mRNA profiling of 20 esophageal squamous cell carcinoma (ESCC) using whole genome DNA microarrays for identification of novel biomarkers. We chose several novel candidates including periostin (POSTN), lumican (LUM), four and a half LIM domains 1 (FHL1), collagen triple helix repeat containing 1 (CTHRC1) and PTRF interacting protein alpha 1 (PPFIA1) to carry out immunohistochemistry‐based validation on a larger sample set using tissue microarrays. Overexpression of periostin was observed in 139/140 (99%) of cases while. lumican was overexpressed in 141/141(100%) of cases and expression of FHL1 was found to be decreased in 132/145 (91%) of cases. These markers could be further tested in sera of patients as candidates for early detection of this cancer.This work was supported by an Independent Senior Research Fellowship to MKK from the Indian Council of Medical Research, New Delhi, India.

Genetic Manipulation of Periostin Expression in the Heart Does Not Affect Myocyte Content, Cell Cycle Activity, or Cardiac Repair

Following a pathological insult, the adult mammalian heart undergoes hypertrophic growth and remodeling of the extracellular matrix. Although a small subpopulation of cardiomyocytes can reenter the cell cycle following cardiac injury, the myocardium is largely thought to be incapable of significant regeneration. Periostin, an extracellular matrix protein, has recently been proposed to induce reentry of differentiated cardiomyocytes back into the cell cycle and promote meaningful repair following myocardial infarction. Here, we show that although periostin is induced in the heart following injury, it does not stimulate DNA synthesis, mitosis, or cytokinesis of cardiomyocytes in vitro or in vivo. Mice lacking the gene encoding periostin and mice with inducible overexpression of full-length periostin were analyzed at baseline and after myocardial infarction. There was no difference in heart size or a change in cardiomyocyte number in either periostin transgenic or gene-targeted mice at baseline. Quantification of proliferating myocytes in the periinfarct area showed no difference between periostin-overexpressing and -null mice compared with strain-matched controls. In support of these observations, neither overexpression of periostin in cell culture, via an adenoviral vector, nor stimulation with recombinant protein induced DNA synthesis, mitosis, or cytokinesis. Periostin is a regulator of cardiac remodeling and hypertrophy and may be a reasonable pharmacological target to mitigate heart failure, but manipulation of this protein appears to have no obvious effect on myocardial regeneration.

Periostin promotes invasiveness and resistance of pancreatic cancer cells to hypoxia-induced cell death: role of the β4 integrin and the PI3k pathway

Pancreatic ductal adenocarcinoma is a devastating disease, characterized by a rapid progression and poor treatment response. Using gene expression profiling of pancreatic cancer tissues, we previously identified periostin as a potential diagnostic and therapeutic target. In this study, we report the overexpression of periostin in a larger set of pancreatic cancer tissues and show that although the periostin transcript is exclusively expressed in tumour cells, the protein product is only detected in the extracellular matrix adjacent to cancer cells. Using an enzyme-linked immunosorbent assay (ELISA) assay, we show significantly increased levels of periostin in the sera of pancreatic cancer patients compared to non-cancer controls. We demonstrate that periostin promotes the invasiveness of tumour cells by increasing the motility of cells without inducing expression of proteases, and enhances the survival of tumour cells exposed to hypoxic conditions. At the molecular level, we provide evidence that the alpha(6)beta(4) integrin complex acts as the cell receptor of periostin in pancreatic cancer cells and that interaction promotes phosphorylation of focal adhesion kinase (FAK) and protein kinase B (AKT) though activation of the PI3 kinase pathway, but not the RAS/MEK/ERK pathway. These findings suggest an important role of periostin in pancreatic cancer and provide a rationale to study periostin for diagnostic and therapeutic applications.

A Chemical Proteomics Approach for the Identification of Accessible Antigens Expressed in Human Kidney Cancer

A promising avenue toward the development of more selective anticancer drugs consists in the targeted delivery of bioactive molecules to the tumor environment by means of binding molecules specific to tumor-associated markers. We have used a chemical proteomics approach based on the ex vivo perfusion and biotinylation of accessible structures within surgically resected human kidneys with tumor to gain information about accessible and abundant antigens that are overexpressed in human cancer. This procedure led to the selective labeling with biotin of vascular structures. Biotinylated proteins were purified on streptavidin resin and identified using mass spectrometric methodologies, revealing 637 proteins, 184 of which were only found in tumor specimens and 223 of which were only found in portions of normal kidneys. Immunohistochemical and PCR analysis confirmed that several of the putative cancer antigens identified in this study are indeed preferentially expressed in tumors. In conclusion, we have developed a methodology that allows the identification of accessible biomarkers in human tissues. The tumor-associated antigens identified in this study may be suitable targets for antibody-based anticancer therapies. The experimental approach described here should be applicable to other surgical specimens and to other pathologies as well as to the study of basic physiological and immunological processes.

Vascular Injury Induces Expression of Periostin

Periostin mRNA is among the most strongly upregulated transcripts in rat carotid arteries after balloon injury. The goal of the present study was to gain insight into the significance of periostin in the vasculature. Periostin expression after injury was localized to smooth muscle cells of the neointima and the adventitia. The expression of periostin in smooth muscle cells in vitro was not regulated by cytokines such as fibroblast growth factor-2 (FGF-2). In contrast, stimulation of MC3T3-E1 osteoblastic cells, NIH3T3 fibroblasts, or mesenchymal C3H10T1/2 cells with FGF-2 reduced periostin mRNA levels to <5% of controls, whereas conversely bone morphogenetic protein-2 (BMP-2) increased periostin mRNA levels. Periostin expression was induced and maintained during retinoic acid-induced smooth muscle cell differentiation in A404 cells. In addition, overexpression of periostin in C3H10T1/2 cells caused an increase in cell migration that could be blocked with an anti-periostin antibody. Periostin expression is associated with smooth muscle cell differentiation in vitro and promotes cell migration. Unlike other mesenchymally derived cell lines, periostin expression is not regulated by FGF-2 in smooth muscle cells. This distinction may be useful in discriminating smooth muscle and fibroblast lineages.