Osteopontin regulates epithelial mesenchymal transition-associated growth of hepatocellular cancer in a mouse xenograft model. Ann Surg. 2012;255:319-325. [PMID: 22241292 DOI: 10.1097/SLA.0b013e31823e3a1c]

The Application of Aptamer and Research Progress in Liver Disease

Aptamers, as a kind of small-molecule nucleic acid, have attracted much attention since their discovery. Compared with biological reagents such as antibodies, aptamers have the advantages of small molecular weight, low immunogenicity, low cost, and easy modification. At present, aptamers are mainly used in disease biomarker discovery, disease diagnosis, treatment, and targeted drug delivery vectors. In the process of screening and optimizing aptamers, it is found that there are still many problems need to be solved such as the design of the library, optimization of screening conditions, the truncation of screened aptamer, and the stability and toxicity of the aptamer. In recent years, the incidence of liver-related diseases is increasing year by year and the treatment measures are relatively lacking, which has attracted the people's attention in the application of aptamers in liver diseases. This article mainly summarizes the research status of aptamers in disease diagnosis and treatment, especially focusing on the application of aptamers in liver diseases, showing the crucial significance of aptamers in the diagnosis and treatment of liver diseases, and the use of Discovery Studio software to find the binding target and sequence of aptamers, and explore their possible interaction sites.

RNA Aptamer Targeting of Adam8 in Cancer Growth and Metastasis

Cancer progression depends on an accumulation of metastasis-supporting physiological changes, which are regulated by cell-signaling molecules. In this regard, a disintegrin and metalloproteinase 8 (Adam8) is a transmembrane glycoprotein that is selectively expressed and induced by a variety of inflammatory stimuli. In this study, we identified Adam8 as a sox2-dependent protein expressed in MDA-MB-231 breast cancer cells when cocultured with mesenchymal-stem-cell-derived myofibroblast-like cancer-associated fibroblasts (myCAF). We have previously found that myCAF-induced cancer stemness is required for the maintenance of the myCAF phenotype, suggesting that the initiation and maintenance of the myCAF phenotype require distinct cell-signaling crosstalk pathways between cancer cells and myCAF. Adam8 was identified as a candidate secreted protein induced by myCAF-mediated cancer stemness. Adam8 has a known sheddase function against which we developed an RNA aptamer, namely, Adam8-Apt1-26nt. The Adam8-Apt1-26nt-mediated blockade of the extracellular soluble Adam8 metalloproteinase domain abolishes the previously initiated myCAF phenotype, or, termed differently, blocks the maintenance of the myCAF phenotype. Consequently, cancer stemness is significantly decreased. Xenograft models show that Adam8-Apt-1-26nt administration is associated with decreased tumor growth and metastasis, while flow cytometric analyses demonstrate a significantly decreased fraction of myCAF after Adam8-Apt-1-26nt treatment. The role of soluble Adam8 in the maintenance of the myCAF phenotype has not been previously characterized. Our study suggests that the signal pathways for the induction or initiation of the myCAF phenotype may be distinct from those involved with the maintenance of the myCAF phenotype.

Maintaining Myofibroblastic-Like Cancer-Associated Fibroblasts by Cancer Stemness Signal Transduction Feedback Loop

Background: Myofibroblast-like cancer-associated fibroblasts (myCAF) in the tumor microenvironment (TME) promote cancer stemness, growth, and metastasis. Cancer cell-derived osteopontin (OPN) has been reported as a biomarker related to malignant cancer growth. In this study, we confirm that cancer cell stemness is required for the maintenance of an OPN-induced myCAF phenotype. Methods: MDA-MB-231 or HepG2 cells and Sox2 knockout variants were co-cultured with human mesenchymal stem cells (MSC). In selected instances, the OPN bioactivity inhibitor OPN-R3 aptamer (APT), OPN-R3 mutant aptamer (MuAPT), or cancer cell stemness inhibitor BBI-608 were added separately. MDA-MB-231 cancer stemness and myCAF markers were quantified by real-time PCR. Stemness-lacking cancer cell mice models were created to confirm that stemness is required for the maintenance of the OPN-induced myCAF phenotype in vivo. Results: In an MDA-MB-231 co-culture system, myCAF and stemness markers increased. Osteopontin and stemness blockade in this co-culture system decreased both myCAF and stemness marker expression, but OPN blockade after 72 hours had no effect. In contrast, when BBI608 was added at 72 hours, myCAF markers were abated after 36-hour treatment. Replacing wildtype with MDA-MB-231(-/-sox2) in co-cultures at 72 hours decreased myCAF marker expression to baseline despite the Western blot confirming the presence of OPN. Conversely, replacing MDA-MB-231(-/-sox2) cells with wildtype increased myCAF marker expression to a level equivalent to the MDA-MB-231+MSC co-culture system. In vivo osteopontin blockade diminished stemness and myCAF marker expression and stemness lacking cancer cell models, indicated by decreasing myCAF presence. Experiments were repeated in a HepG2 cell line with identical results. Conclusions: Cancer and myCAF crosstalk increases myCAF maintenance and cancer cell stemness. In this study using human breast and liver cancer cell lines, maintenance of the OPN-induced myCAF phenotype also requires cancer stemness. This indicates that the myCAF phenotype requires two distinct signaling pathways: initiation and maintenance.

Tumor: Stroma Interaction and Cancer

The understanding of how normal cells transform into tumor cells and progress to invasive cancer and metastases continues to evolve. The tumor mass is comprised of a heterogeneous population of cells that include recruited host immune cells, stromal cells, matrix components, and endothelial cells. This tumor microenvironment plays a fundamental role in the acquisition of hallmark traits, and has been the intense focus of current research. A key regulatory mechanism triggered by these tumor-stroma interactions includes processes that resemble epithelial-mesenchymal transition, a physiologic program that allows a polarized epithelial cell to undergo biochemical and cellular changes and adopt mesenchymal cell characteristics. These cellular adaptations facilitate enhanced migratory capacity, invasiveness, elevated resistance to apoptosis, and greatly increased production of ECM components. Indeed, it has been postulated that cancer cells undergo epithelial-mesenchymal transition to invade and metastasize.In the following discussion, the physiology of chronic inflammation, wound healing, fibrosis, and tumor invasion will be explored. The key regulatory cytokines, transforming growth factor β and osteopontin, and their roles in cancer metastasis will be highlighted.

Simultaneous single-cell phenotype analysis of hepatocellular carcinoma CTCs using a SERS-aptamer based microfluidic chip

Hepatocellular carcinoma (HCC) is a harmful malady that truly debilitates human health, and hence it is of significance to isolate and on-line profile the phenotype of HCC cells for further diagnosis and therapy. We developed a novel strategy for efficient capture and in situ heterogeneous phenotype analysis of circulating tumor cells (CTCs) at the single-cell level based on surface-enhanced Raman scattering (SERS) fingerprint characteristics. Herein, a new microfluidic chip with lantern-like bypass structure was designed to capture CTCs by their large size from whole blood. Furthermore, two types of SERS-aptamer nanotags were fabricated, realizing spectral recognition of single CTCs in accordance with the surface membrane protein expression. Up to 84% of CTCs with a purity of 95% were captured from whole blood samples using the present SERS-aptamer based microfluidic chip at 20 μL min^-1. The results showed that the proposed strategy can successfully identify HCC cell subtypes by SERS measurements, which was related to the clinical surface biomarkers. This may open a new avenue for serving as a powerful tool of cancer diagnosis and prognosis evaluation.

Prognostic and predictive significance of osteopontin in malignant neoplasms

Osteopontin is an extracellular matrix protein which is produced by different types of cells and plays an important functional role in many biological processes. This review discusses the main functions of osteopontin, its role in the progression and chemoresistance of malignant neoplasms, in the regulation of epithelial-mesenchymal transition, angiogenesis, and the body’s immune response to the tumor. The article considers the currently known mechanisms by which osteopontin affects to the survival, mobility and invasion of tumor cells, to tumor sensitivity to drug treatment, as well as the prospects for a integrated study of the predictive significance of osteopontin, markers of hypoxia, angiogenesis, epithelial- mesenchymal transition, and immunological tolerance.

Conservation of Epithelial-to-Mesenchymal Transition Process in Neural Crest Cells and Metastatic Cancer

Epithelial to mesenchymal transition (EMT) is a highly conserved cellular process in several species, from worms to humans. EMT plays a fundamental role in early embryogenesis, wound healing, and cancer metastasis. For neural crest cell (NCC) development, EMT typically results in forming a migratory and potent cell population that generates a wide variety of cell and tissue, including cartilage, bone, connective tissue, endocrine cells, neurons, and glia amongst many others. The degree of conservation between the signaling pathways that regulate EMT during development and metastatic cancer (MC) has not been fully established, despite ample studies. This systematic review and meta-analysis dissects the major signaling pathways involved in EMT of NCC development and MC to unravel the similarities and differences. While the FGF, TGFβ/BMP, SHH, and NOTCH pathways have been rigorously investigated in both systems, the EGF, IGF, HIPPO, Factor Receptor Superfamily, and their intracellular signaling cascades need to be the focus of future NCC studies. In general, meta-analyses of the associated signaling pathways show a significant number of overlapping genes (particularly ligands, transcription regulators, and targeted cadherins) involved in each signaling pathway of both systems without stratification by body segments and cancer type. Lack of stratification makes it difficult to meaningfully evaluate the intracellular downstream effectors of each signaling pathway. Finally, pediatric neuroblastoma and melanoma are NCC-derived malignancies, which emphasize the importance of uncovering the EMT events that convert NCC into treatment-resistant malignant cells.

Osteopontin: A Key Regulator of Tumor Progression and Immunomodulation

Simple Summary

Anti-PD-1/PD-L1 and anti-CTLA-4-based immune checkpoint blockade (ICB) immunotherapy have recently emerged as a breakthrough in human cancer treatment. Durable efficacy has been achieved in many types of human cancers. However, not all human cancers respond to current ICB immunotherapy and only a fraction of the responsive cancers exhibit efficacy. Osteopontin (OPN) expression is highly elevated in human cancers and functions as a tumor promoter. Emerging data suggest that OPN may also regulate immune cell function in the tumor microenvironment. This review aims at OPN function in human cancer progression and new findings of OPN as a new immune checkpoint. We propose that OPN compensates PD-L1 function to promote tumor immune evasion, which may underlie human cancer non-response to current ICB immunotherapy.

Abstract

OPN is a multifunctional phosphoglycoprotein expressed in a wide range of cells, including osteoclasts, osteoblasts, neurons, epithelial cells, T, B, NK, NK T, myeloid, and innate lymphoid cells. OPN plays an important role in diverse biological processes and is implicated in multiple diseases such as cardiovascular, diabetes, kidney, proinflammatory, fibrosis, nephrolithiasis, wound healing, and cancer. In cancer patients, overexpressed OPN is often detected in the tumor microenvironment and elevated serum OPN level is correlated with poor prognosis. Initially identified in activated T cells and termed as early T cell activation gene, OPN links innate cells to adaptive cells in immune response to infection and cancer. Recent single cell RNA sequencing revealed that OPN is primarily expressed in tumor cells and tumor-infiltrating myeloid cells in human cancer patients. Emerging experimental data reveal a key role of OPN is tumor immune evasion through regulating macrophage polarization, recruitment, and inhibition of T cell activation in the tumor microenvironment. Therefore, in addition to its well-established direct tumor cell promotion function, OPN also acts as an immune checkpoint to negatively regulate T cell activation. The OPN protein level is highly elevated in peripheral blood of human cancer patients. OPN blockade immunotherapy with OPN neutralization monoclonal antibodies (mAbs) thus represents an attractive approach in human cancer immunotherapy.

SUMO1 modification of methyltransferase-like 3 promotes tumor progression via regulating Snail mRNA homeostasis in hepatocellular carcinoma

Rationale: Hepatocellular carcinoma (HCC) is one of the leading causes of mortality worldwide. Methyltransferase-like 3 (Mettl3), an RNA N6-methyladenosine (m6A) methyltransferase, has been shown to act as an oncogene in several human cancers. However, the regulatory role of posttranslational modifications of Mettl3 in liver cancer remains elusive.

Methods: SUMOylation was analyzed using immunoprecipitation and western blot assays. In vitro and in vivo biological functions were examined using MTS, colony formation, wound healing, transwell, apoptosis, and viability assays and the BALB/c nude mouse model, respectively. Immunohistochemistry was conducted to evaluate the prognostic value of Mettl3 expression in HCC. The regulatory mechanism of Mettl3 in HCC was investigated by m6A dot blot, immunofluorescence, dual luciferase reporter, protein stability, and RNA stability assays.

Results: Mettl3 was found to be SUMOylated by a small ubiquitin-like modifier SUMO1. Further, SUMOylation of Mettl3 was increased upon mitogen stimulation, which correlated with UBC9 upregulation, and was positively correlated with high metastatic potential of liver cancer. Finally, SUMOylation of Mettl3 was found to regulate HCC progression via controlling Snail mRNA homeostasis in an m6A methyltransferase activity-dependent manner.

Conclusions: This study revealed a novel mechanism of SUMOylated Mettl3-mediated Snail mRNA homeostasis, identifying the UBC9/SUMOylated Mettl3/Snail axis as a novel mediator of the SUMO pathway involved in HCC progression.

Identification of Secreted Phosphoprotein 1 (SPP1) as a Prognostic Factor in Lower-Grade Gliomas

OBJECTIVE

Secreted phosphoprotein 1 (SPP1) is an important extracellular glycoprotein that is associated with immune regulation, tumorigenesis, and cell signaling. However, the prognostic value of SPP1 in patients with glioma has not yet been clarified, especially in lower-grade gliomas. The objective of this study is to evaluate the prognostic merit of SPP1 in lower-grade gliomas.

METHODS

The messenger RNA (mRNA) expression of SPP1 in about 1000 cancer cell lines was explored by using the data from the Cancer Cell Line Encyclopedia database. The Oncomine database was mined to evaluate the mRNA expression of SPP1 in lower-grade glioma, glioblastoma, and normal brain tissues. The correlation between SPP1 mRNA expression and overall survival of patients with glioma from The Cancer Genome Atlas database was analyzed.

RESULTS

SPP1 mRNA expression of glioma was ranked as the eighth highest of all cancer cell lines in the Cancer Cell Line Encyclopedia database. The data from the Oncomine database suggested that SPP1 expression was significantly high in glioblastoma compared with normal brain tissues but was not significantly high in lower-grade glioma compared with normal brain tissue. Analysis of the RNA-Seq data from The Cancer Genome Atlas database showed that the increased SPP1 mRNA expression in lower-grade glioma was significantly associated with poor survival outcomes in patients with lower-grade glioma. Multivariate Cox regression analysis showed that SPP1 might be considered as an independent prognostic factor in lower-grade gliomas.

CONCLUSIONS

The present study showed that SPP1 overexpression is related to worse overall survival in patients with lower-grade glioma. Moreover, SPP1 could be considered as an independent factor in lower-grade gliomas.

Osteopontin promotes hepatocellular carcinoma progression via the PI3K/AKT/Twist signaling pathway

The epithelial-mesenchymal transition (EMT) serves critical roles in the migration, invasion and metastasis of human cancer cells. This process is initiated by regulation of E-cadherin expression by the major inducers of EMT. Previous studies reported that osteopontin (OPN) is essential for hepatocellular carcinoma (HCC) metastasis as it facilitates the EMT in HCC. However, the role and clinical significance of OPN as an EMT regulator in HCC remains unknown. The present study revealed that OPN regulated the expression of Twist by activating RAC serine/threonine-protein kinase (Akt), a critical EMT regulator. Interfering with the phosphoinositide 3-kinase (PI3K)/Akt pathway may suppress the expression of Twist enhanced by OPN. Increased Twist levels in HCC were associated with poor survival and tumor recurrence in patients with HCC following surgery. A significant association was observed between OPN expression and Twist levels in HCC, and a combination of these two parameters was revealed to be a more powerful predictor of poor patient prognosis. The findings of the present study indicate that Twist serves an notable role in OPN-mediated metastasis of HCC through activation of the PI3K/Akt pathway. Twist may be a potential therapeutic target for the prevention of HCC metastasis in patients exhibiting high OPN expression.

Sphk2 RNAi nanoparticles suppress tumor growth via downregulating cancer cell derived exosomal microRNA

Exosomes secreted from cancer cells promote tumor progression through the transfection of containing microRNA (miRNA), mRNAs and proteins. Yet, little of this knowledge has translated into the therapeutic application. Herein, we propose a tumor therapeutic strategy via decreasing exosomal miRNA secretion. The study designed small interfering RNA (siRNA) loaded nanoparticles to downregulate sphingosine kinase 2 (Sphk2) and investigate their potential in decreasing exosomal oncogenic miRNA content and inhibiting tumor growth. The synthesized lipid (2E)-4-(dioleostearin)-amino-4‑carbonyl-2-butenoic (DC) and chitosan were utilized to produce siRNA loaded nanoparticles (DC/CS-siRNA NPs), with optimal siRNA complexation and high transfection efficacy. We demonstrated that Sphk2 gene silencing induced by nanoparticles in hepatocellular carcinoma (HCC) cells could reduce miRNA-21 sorting into exosomes, contributing to the inhibition of tumor cell migration and tumorigenic function of exosomes to normal liver cells. Furthermore, in xenograft mouse model, Sphk2 siRNA loaded DC/CS NPs could significantly block tumor progression of malignancy HCC. These results suggest a new therapeutic approach for tumor treatment by ablating oncogenic miRNA in malicious exosomes.

Aptamer: A potential oligonucleotide nanomedicine in the diagnosis and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers with a high mortality rate. Late diagnosis and poor prognosis are still a major drawback since curative therapies such as liver resection and liver transplantation are effective only for an early stage HCC. Development of novel molecular targeting therapies against HCC may provide new options that will improve the efficiency of the diagnosis and the success of the therapy, thus ameliorating the life expectancy of the patients. The aptamer is an oligonucleotide nanomedicine that has high binding affinity and specificity to small and large target molecules in the intracellular and extracellular environment with agonist or antagonist function. Currently, several aptamers for diagnostic and therapeutic purposes are under development to recognize different molecules of HCC. In in vitro models, the aptamer has been shown to be able to reduce the growth of HCC cells and increase the sensitivity to conventional chemotherapies. In in vivo mouse models, aptamer could induce cell apoptosis with antitumor activity. Overall data had shown that aptamer has limited toxicity and might be safe in clinical application. This review summarizes recent information of aptamer as a potential oligonucleotide nanomedicine tool, in diagnostics, targeted therapy, and as drug delivery nano-vehicles.

Osteopontin promotes epithelial-mesenchymal transition of hepatocellular carcinoma through regulating vimentin

Our previous studies have found that osteopontin (OPN) is a promoter for hepatocellular carcinoma (HCC) progression. However, the molecular mechanism by which OPN enhances HCC metastasis remains elusive. Epithelial-mesenchymal transition (EMT) of cancer cells plays a pivotal role in promoting metastatic process. In this study, we demonstrated that OPN promotes HCC metastasis by inducing an EMT-like, more aggressive cellular phenotype in vitro and in vivo. Furthermore, OPN was identified to interact with vimentin by reciprocal OPN and vimentin immunoprecipitation as well as co-immunofluorescence examination. By using deletion mutants, we found that the residues between 246 and 406 in vimentin are required for binding to OPN. Importantly, OPN significantly increased vimentin stability through inhibition of its protein degradation. Knockdown of vimentin neutralized the EMT induced by OPN both in vitro and in vivo. Moreover, a significant correlation between OPN and vimentin levels was found in clinical HCC specimens and their combination had a worse prognosis with shorter overall survival (OS) and time to recurrence (TTR). In multivariate analysis, OPN and their combination were demonstrated to be independent prognostic indicators for OS and TTR of HCC patients. Collectively, this study indicates that OPN can induce EMT of HCC cells through increasing vimentin stability, which provides more in-depth understanding about the molecular mechanisms of OPN in promoting HCC metastasis and opens tantalizing therapeutic possibilities in HCC.

A humanized osteopontin mouse model and its application in immunometabolic obesity studies

Osteopontin (OPN) is a multifunctional protein involved in several inflammatory processes and pathogeneses including obesity-related disorders and cancer. OPN binds to a variety of integrin receptors and CD44 resulting in a proinflammatory stimulus. Therefore, OPN constitutes a novel interesting target to develop new therapeutic strategies, which counteract OPN's proinflammatory properties. We established a humanized SPP1 (hSPP1) mouse model and evaluated its suitability as a model for obesity and insulin resistance. Unchallenged hSPP1 animals did not significantly differ in body weight and gross behavioral properties compared to wild-type (WT) animals. High-fat diet-challenged hSPP1 similarly developed obesity and inflammation, whereas insulin resistance was markedly changed. However, OPN expression profile in tissues was significantly altered in hSPP1 compared to WT depending on the diet. In conclusion, we developed a versatile humanized model to study the action of OPN in vivo and to develop strategies that target human OPN in a variety of pathologies.

Osteopontin induces autophagy to promote chemo-resistance in human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a major health burden worldwide for its high incidence and mortality. Osteopontin (OPN) is a chemokine-like, matricellular phosphoglycoprotein whose expression is elevated in various types of cancer including HCC. OPN has been shown to be involved in tumorigenesis, chemo-resistance, metastasis and sustaining stem-like properties of cancer cells. Autophagy is a cellular process by which cytoplasmic components are degraded and recycled for maintaining cellular homeostasis. There is increasing evidence supports that autophagy plays a critical role for stem-like properties and chemo-resistance of cancer cells. However, the relationship between OPN and autophagy in maintaining cancer stem-like properties and chemo-resistance is yet to be clarified. Herein, we found that secreted OPN induced autophagy via binding with its receptor integrin αvβ3 and sustaining FoxO3a stability. OPN-elicited autophagy could promote cancer cell survival and resistance to chemotherapy drugs, as well as stem-like properties. Our findings indicated that OPN was capable of promoting chemo-resistance of HCCs via autophagy, which might provide a new strategy for the treatment of HCC.

Osteopontin (OPN/SPP1) isoforms collectively enhance tumor cell invasion and dissemination in esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) is often diagnosed at an advanced stage, thus understanding the molecular basis for EAC invasion and metastasis is critical. Here we report that SPP1/OPN was highly overexpressed in primary EACs and intracellularly localized to tumor cells. We further demonstrate that all known OPN isoforms (OPNa, b, c, 4 and 5) were frequently co-overexpressed in primary EACs. Distinct pro-invasion and dissemination phenotypes of isoform-specific OPNb and OPNc stable transfectants were observed. Expression of OPNb significantly enhanced cell migration and adhesion to laminin. In contrast, OPNc cells showed significantly decreased cell migration yet increased cell detachment. Enhanced invasion, both in vitro and in vivo, was observed for OPNb- but not OPNc-expressing cells. Inhibition of RGD integrins, one family of OPN receptors, attenuated OPNb cell migration, abrogated OPNb cell adhesion and significantly reduced OPNb cell clonogenic survival but did not affect OPNc phenotypes, indicating that OPNb but not OPNc acts through integrin-dependent signaling. Differential expression of vimentin, E-cadherin and β-catenin in OPN stable cells may account for the variation in cell adhesion and detachment between these isoforms. We conclude that while all OPN isoforms are frequently co-overexpressed in primary EACs, isoforms OPNb and OPNc enhance invasion and dissemination through collective yet distinct mechanisms.

Interleukin-6 enhances cancer stemness and promotes metastasis of hepatocellular carcinoma via up-regulating osteopontin expression

Interleukin-6 (IL-6), one of the most important inflammatory cytokines, plays a pivotal role in metastasis and stemness of solid tumors. However, the underlying mechanisms of IL-6 in HCC metastasis remain unclear. In the present study, we demonstrated that stemness and metastatic potential of HCC cells were significantly enhanced after IL-6 stimulation. IL-6 could induce expression of osteopontin (OPN), along with other stemness-related genes, including HIF1α, BMI1, and HEY1. Block of OPN induction could significantly abrogate the effect of IL-6 on stemness and metastasis of HCC cells. Furthermore, IL-6 level was positively correlated with OPN in HCC. Patients with high plasma IL-6 or OPN level had poorer prognosis. In multivariate analysis, IL-6 and OPN were demonstrated to be independent prognostic indicators for HCC patients, and their combination had a better prognostic performance than IL-6 or OPN alone. Collectively, our findings indicate that IL-6 could enhance stemness and promote metastasis of HCC via up-regulating OPN expression, which can be a potential therapeutic target for combating HCC metastasis, and the combination of IL-6 and OPN serves as a promising prognostic predictor for HCC.

Role of Osteopontin in Liver Diseases

Osteopontin (OPN), a multifunctional protein, is involved in numerous pathological conditions including inflammation, immunity, angiogenesis, fibrogenesis and carcinogenesis in various tissues. Extensive studies have elucidated the critical role of OPN in cell signaling such as regulation of cell proliferation, migration, inflammation, fibrosis and tumor progression. In the liver, OPN interacts with integrins, CD44, vimentin and MyD88 signaling, thereby induces infiltration, migration, invasion and metastasis of cells. OPN is highlighted as a chemoattractant for macrophages and neutrophils during injury in inflammatory liver diseases. OPN activates hepatic stellate cells (HSCs) to exert an enhancer in fibrogenesis. The role of OPN in hepatocellular carcinoma (HCC) has also generated significant interests, especially with regards to its role as a diagnostic and prognostic factor. Interestingly, OPN acts an opposing role in liver repair under different pathological conditions. This review summarizes the current understanding of OPN in liver diseases. Further understanding of the pathophysiological role of OPN in cellular interactions and molecular mechanisms associated with hepatic inflammation, fibrosis and cancer may contribute to the development of novel strategies for clinical diagnosis, monitoring and therapy of liver diseases.

Aptamers in Therapeutics

Aptamers are single strand DNA or RNA molecules, selected by an iterative process known as Systematic Evolution of Ligands by Exponential Enrichment (SELEX). Due to various advantages of aptamers such as high temperature stability, animal free, cost effective production and its high affinity and selectivity for its target make them attractive alternatives to monoclonal antibody for use in diagnostic and therapeutic purposes. Aptamer has been generated against vesicular endothelial growth factor 165 involved in age related macular degeneracy. Macugen was the first FDA approved aptamer based drug that was commercialized. Later other aptamers were also developed against blood clotting proteins, cancer proteins, antibody E, agents involved in diabetes nephropathy, autoantibodies involved in autoimmune disorders, etc. Aptamers have also been developed against viruses and could work with other antiviral agents in treating infections.

Osteopontin-A Master Regulator of Epithelial-Mesenchymal Transition

Osteopontin (OPN) plays an important functional role in both physiologic and pathologic states. OPN is implicated in the progression of fibrosis, cancer, and metastatic disease in several organ systems. The epithelial-mesenchymal transition (EMT), first described in embryology, is increasingly being recognized as a significant contributor to fibrotic phenotypes and tumor progression. Several well-established transcription factors regulate EMT and are conserved across tissue types and organ systems, including TWIST, zinc finger E-box-binding homeobox (ZEB), and SNAIL-family members. Recent literature points to an important relationship between OPN and EMT, implicating OPN as a key regulatory component of EMT programs. In this review, OPN’s interplay with traditional EMT activators, both directly and indirectly, will be discussed. Also, OPN’s ability to restructure the tissue and tumor microenvironment to indirectly modify EMT will be reviewed. Together, these diverse pathways demonstrate that OPN is able to modulate EMT and provide new targets for directing therapeutics.

[Advances in Research of Osteopontion and Its Receptor CD44v in Tumor Invasion and Metastasis]

Osteopontin (OPN) is a multifunctional, extracellular matrix-associated, secretory, glyco-protein. It can be used as an adhesion protein involved in tumor cell adhesion,migration; but also as a cytokine, promoting tumor angiogenesis, evading immune surveillance and inhibiting cellular apoptosis. CD44v glycoprotein, is one of the cell surface adhesion molecule that mediates cell-matrix and cell-cell interactions. Extensive research has suggested the important role of OPN in regulating signaling pathways that contribute to tumor progression and metastasis, and the serum level is associated with the prognosis of various malignancies. Therefore, clarifying OPN in the molecular mechanisms of tumor progression and its signaling pathway contributes to seeking a novel anti-cancer therapy.

Green tea component epigallocatechin-3-gallate decreases expression of osteopontin via a decrease in mRNA half-life in cell lines of metastatic hepatocellular carcinoma

INTRODUCTION

Osteopontin (OPN) mediates metastasis and invasion of hepatocellular carcinoma (HCC). Epigallocatechin-3-gallate (EGCG), found in green tea, suppresses HCC tumor growth in vitro. We sought to investigate the role of EGCG in modulating OPN in cell lines of metastatic HCC.

METHODS

Experimental HCC cell lines included HepG2 and MHCC-97H HCC cells, which express high levels of OPN, and the Hep3B cells, which express lesser levels of OPN. Cells were treated with EGCG (0.02-20 μg/mL) before measurement of OPN with enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction. Scratch assay measured cell migration. Binding of the OPN promoter to RNA pol II was evaluated by the use of Chromatin-IP assay after EGCG treatment. Transcriptional regulation of OPN was investigated with luciferase reporter plasmids containing various deletion fragments of the human OPN promoter. Measurement of the half-life of OPN mRNA was conducted using actinomycin D.

RESULTS

Treatment of MHCC-97H and HepG2 cells with 2 μg/mL and 20 μg/mL EGCG caused a ∼6-fold and ∼90-fold decrease in secreted protein levels of OPN (All P < .001). OPN mRNA was decreased with EGCG concentrations of 0.2-20 μg/ml (All P < .001). The 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (ie, MTT) assay revealed that differences in OPN expression were not due to viability of the HCC cell lines. Promoter assay and chromatin immunoprecipitation analysis revealed no effect of EGCG on the transcriptional regulation of OPN. Posttranscriptionally, EGCG decreased the half-life of OPN mRNA from 16.8 hours (95% confidence interval 9.0-125.1) to 2.5 hours (95% confidence interval 2.1-3.2) (P < .001). Migration was decreased in EGCG treated cells at 24 hours (8.0 ± 2.4% vs 21.2 ± 10.8%, P < .01) and at 48 hours (13.2 ± 3.6% vs 53.5 ± 19.8%, P < .001).

CONCLUSION

We provide evidence that EGCG decreases OPN mRNA and secreted OPN protein levels by decreasing the half-life of OPN mRNA in MHCC-97H cells. The translatability of EGCG for patients with HCC is promising, because EGCG is an inexpensive, easily accessible chemical with an extensive history of safety.

Snail regulates Nanog status during the epithelial-mesenchymal transition via the Smad1/Akt/GSK3β signaling pathway in non-small-cell lung cancer

The epithelial–mesenchymal transition (EMT), a crucial step in cancer metastasis, is important in transformed cancer cells with stem cell-like properties. In this study, we established a Snail-overexpressing cell model for non-small-cell lung cancer (NSCLC) and investigated its underlying mechanism. We also identified the downstream molecular signaling pathway that contributes to the role of Snail in regulating Nanog expression. Our data shows that high levels of Snail expression correlate with metastasis and high levels of Nanog expression in NSCLC. NSCLC cells expressing Snail are characterized by active EMT characteristics and exhibit an increased ability to migrate, chemoresistance, sphere formation, and stem cell-like properties. We also investigated the signals required for Snail-mediated Nanog expression. Our data demonstrate that LY294002, SB431542, LDN193189, and Noggin pretreatment inhibit Snail-induced Nanog expression during EMT. This study shows a significant correlation between Snail expression and phosphorylation of Smad1, Akt, and GSK3β. In addition, pretreatment with SB431542, LDN193189, or Noggin prevented Snail-induced Smad1 and Akt hyperactivation and reactivated GSK3β. Moreover, LY294002 pretreatment prevented Akt hyperactivation and reactivated GSK3β without altering Smad1 activation. These findings provide a novel mechanistic insight into the important role of Snail in NSCLC during EMT and indicate potentially useful therapeutic targets for NSCLC.

Osteopontin mediates an MZF1-TGF-β1-dependent transformation of mesenchymal stem cells into cancer-associated fibroblasts in breast cancer

Interactions between tumor cells and cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TMEN) significantly influence cancer growth and metastasis. Transforming growth factor-β (TGF-β) is known to be a critical mediator of the CAF phenotype, and osteopontin (OPN) expression in tumors is associated with more aggressive phenotypes and poor patient outcomes. The potential link between these two pathways has not been previously addressed. Utilizing in vitro studies using human mesenchymal stem cells (MSCs) and MDA-MB231 (OPN+) and MCF7 (OPN−) human breast cancer cell lines, we demonstrate that OPN induces integrin-dependent MSC expression of TGF-β1 to mediate adoption of the CAF phenotype. This OPN-TGF-β1 pathway requires the transcription factor, myeloid zinc finger 1 (MZF1). In vivo studies with xenotransplant models in NOD-scid mice showed that OPN expression increases cancer growth and metastasis by mediating MSC-to-CAF transformation in a process that is MZF1- and TGF-β1-dependent. We conclude that tumor-derived OPN engenders MSC-to-CAF transformation in the microenvironment to promote tumor growth and metastasis via the OPN-MZF1-TGF-β1 pathway.

Screening candidate metastasis-associated genes in three-dimensional HCC spheroids with different metastasis potential

PURPOSE

Previously, we have established a tissue-like HCC spheroid which better mirrors the biological features of tumorigenesis and metastasis. This study was to find out metastasis-associated genes between two 3D HCC spheroids with different metastasis potential using comparative PCR arrays.

MATERIALS AND METHODS

Two HCC spheroids derived from high-metastatic MHCC97H cells and low-metastatic Hep3B cells were formed respectively in a rotating wall vessel bioreactor after 3D culture for 15 days. The candidate metastasis-associated genes related to cell adhesion, matrix secretion and invasion in HCC spheroids were screened by RT² profiler PCR arrays. The expression patterns of several differentially-expressed genes were further confirmed by real-time RT-PCR.

RESULTS

Total of 123 differential expression genes (fold-change>2) were found between two HCC spheroids, including 70 up-regulated genes (VCAM-1, IL-1β, CD44, tenascin C, SPP1, fibronectin, MMP-2, MMP-7, etc) and 53 down-regulated genes (E-cadherin, CTNND2, etc) in the high-metastatic spheroid. Function classification showed that the number of up-regulated genes related to adhesion molecules mediating cell-matrix interactions and matrix secretion was significantly higher in high-metastatic spheroid than that in low-metastatic spheroid. In contrast, the expressions of adhesion molecules maintaining homotypic tumor cell adhesion were decreased in metastatic spheroid as compared with that in low-metastatic spheroid. In addition, the expression pattern of seven selected genes associated with tumor metastasis measured by real-time RT-PCR were consistent with results of PCR arrays.

CONCLUSIONS

Obvious differences between two HCC spheroids in gene expression patterns of adhesion molecules, matrix secretion, invasion and other molecules may determine the different metastatic characteristics and malignant phenotype of HCC spheroid.

Molecular profiling of stroma identifies osteopontin as an independent predictor of poor prognosis in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common type of primary cancer in the liver. ICC is an aggressive cancer with poor prognosis and limited therapeutic strategies. The identification of new drug targets and prognostic biomarkers is an important clinical challenge for ICC. The presence of an abundant stroma is a histological hallmark of ICC. Given the well-established role of the stromal compartment in the progression of cancer diseases, we hypothesized that relevant biomarkers could be identified by analyzing the stroma of ICC. By combining laser capture microdissection and gene expression profiling, we demonstrate that ICC stromal cells exhibit dramatic genomic changes. We identified a signature of 1,073 nonredundant genes that significantly discriminate the tumor stroma from nontumor fibrous tissue. Functional analysis of differentially expressed genes demonstrated that up-regulated genes in the stroma of ICC were related to cell cycle, extracellular matrix, and transforming growth factor beta (TGFβ) pathways. Tissue microarray analysis using an independent cohort of 40 ICC patients validated at a protein level the increased expression of collagen 4A1/COL4A1, laminin gamma 2/LAMC2, osteopontin/SPP1, KIAA0101, and TGFβ2 genes in the stroma of ICC. Statistical analysis of clinical and pathological features demonstrated that the expression of osteopontin, TGFβ2, and laminin in the stroma of ICC was significantly correlated with overall patient survival. More important, multivariate analysis demonstrated that the stromal expression of osteopontin was an independent prognostic marker for overall and disease-free survival.

CONCLUSION

The study identifies clinically relevant genomic alterations in the stroma of ICC, including candidate biomarkers for prognosis, supporting the idea that tumor stroma is an important factor for ICC onset and progression.

Advances in understanding relationship between osteopontin and metastasis and recurrence of hepatocellular carcinoma

Osteopontin (OPN), first found in normal human tissue, is a secreted phosphorylated glycoprotein and one of the most important adhesion factors. Increased expression of OPN has been found in many types of tumors. OPN plays a very important role in the metastasis and recurrence of hepatocellular carcinoma (HCC). As a tumor marker, OPN may also become a new therapeutic target for cancer. This review aims to elucidate the structure and function of OPN, its role in HCC recurrence and metastasis, and the significance of OPN in HCC diagnosis and treatment.

Functional consequences of WNT3/Frizzled7-mediated signaling in non-transformed hepatic cells

We have previously demonstrated that WNT3 and Frizzled7 (FZD7) expression levelswere upregulated in hepatocellular carcinoma (HCC) and that they directly interact to activate the canonical Wnt/β–catenin pathway in HCC cell lines. In this study, we investigated the functional consequences of WNT3 and FZD7 expression levels in non-transformed hepatic cells to address the question of whether WNT3/FZD7-mediated signal transduction could be involved in cellular transformation. After stable transfection of WNT3 and FZD7, the activation of the Wnt/β–catenin pathway was confirmed by western blot, immunostaining and quantitative real-time reverse transcriptase–PCR (qRT–PCR) analysis in two non-transformed hepatocyte-derived cell lines. In vitro characteristics of the malignant phenotype were measured, including cell proliferation, migration, invasion and anchorage-independent growth in soft agar. Stable expression of WNT3 and FZD7 in the two cell lines led to cellular accumulation of β-catenin and expression of downstream target genes activated by this pathway. In the stable WNT3/FZD7-expressing clones, hepatic cell proliferation, migration, invasion as well as soft agar colony formation were enhanced compared with the non-transformed control cells. The epithelial–mesenchymal transition (EMT) factors, Twist, Snail and Vimentin, were increased in cells expressing WNT3 and FZD7. However, the WNT3/FZD7-expressing cells did not form tumors in vivo. We conclude that activation of the WNT3/FZD7 canonical pathway has a role in the early stages of hepatocarcinogenesis by promoting the acquisition of a malignant phenotype with features of EMT.