SPARC and Hevin expression correlate with tumour angiogenesis in hepatocellular carcinoma

The role of SPARC (secreted protein acidic and rich in cysteine) in the pathogenesis of obesity, type 2 diabetes, and non-alcoholic fatty liver disease

Secreted protein acidic and rich in cysteine (SPARC) is an extracellular matrix glycoprotein with pleiotropic functions, which is expressed in adipose, hepatic, muscular, and pancreatic tissue. Particularly, several studies demonstrated that SPARC is an important player in the context of obesity, diabetes, and fatty liver disease including advanced hepatic fibrosis and hepatocellular carcinoma. Evidence in murine and human samples indicates that SPARC is involved in adipogenesis, cellular metabolism, extracellular matrix modulation, glucose and lipid metabolism, among others. Furthermore, studies in SPARC knockout mouse model showed that SPARC contributes to adipose tissue formation, non-alcoholic fatty liver disease (NAFLD), and diabetes. Hence, SPARC may represent a novel and interesting target protein for future therapeutic interventions or a biomarker of disease progression. This review summarizes the role of SPARC in the pathophysiology of obesity, and extensively revised SPARC functions in physiological and pathological adipose tissue deposition, muscle metabolism, liver, and diabetes-related pathways.

Secretome profiling of Artemisia absinthium extract-loaded polymeric nanoparticle-treated MCF-7 and MDA-MB-231 revealed perturbation in microtubule assembly and cell migration

Introduction

Artemisia absinthium (wormwood) exhibits anticancer properties by inhibiting proliferation and causing cell death in breast cancer. Targeted drug delivery of A. absinthium nanoformulation using N-isopropyl acrylamide, N-vinyl pyrrolidone, and acrylic acid-based polymeric nanoparticles (NVA-AA NPs) was ensured by utilizing features of the tumor microenvironment, although their mechanism of action involved in cytotoxicity remains unknown.

Methods

The present study employed nano LC-MS/MS to identify differences in secretory protein expression associated with the treatment of breast cancer cell lines (MCF-7; MDA-MB-231) by NVA-AA NPs for the determination of affected pathways and easily accessible therapeutic targets. Different bioinformatics tools were used to identify signature differentially expressed proteins (DEPs) using survival analysis by GENT2 and correlation analysis between their mRNA expressions and sensitivity toward small-molecule drugs as well as immune cell infiltration by GSCA.

Results

Analysis by GENT2 revealed 22 signature DEPs with the most significant change in their expression regulation, namely, gelsolin, alpha-fetoprotein, complement component C3, C7, histone H2B type 1-K, histone H2A.Z, H2AX, heat shock cognate 71 kDa protein, heat shock 70 kDa protein 1-like, cytochrome c somatic, GTP-binding nuclear protein Ran, tubulin beta chain, tubulin alpha-1B chain, tubulin alpha-1C chain, phosphoglycerate mutase 1, kininogen 1, carboxypeptidase N catalytic chain, fibulin-1, peroxiredoxins 4, lactate dehydrogenase C, SPARC, and SPARC-like protein 1. Correlation analysis between their mRNA expressions versus immune cell infiltrates showed a positive correlation with antitumor immune response elicited by these NPs as well as a correlation with drug response shown by the GDSC and CTRP drugs in different cancer cells.

Discussion

Our results suggest that NVA-AA NPs were able to invade the tumor microenvironment; transformed the communication network between the cancer cells; affected potential drivers of microtubular integrity, nucleosome assembly, and cell cycle; and eventually caused cell death.

SPARC: a potential target for functional nanomaterials and drugs

Secreted protein acidic and rich in cysteine (SPARC), also termed osteonectin or BM-40, is a matricellular protein which regulates cell adhesion, extracellular matrix production, growth factor activity, and cell cycle. Although SPARC does not perform a structural function, it, however, modulates interactions between cells and the surrounding extracellular matrix due to its anti-proliferative and anti-adhesion properties. The overexpression of SPARC at sites, including injury, regeneration, obesity, cancer, and inflammation, reveals its application as a prospective target and therapeutic indicator in the treatment and assessment of disease. This article comprehensively summarizes the mechanism of SPARC overexpression in inflammation and tumors as well as the latest research progress of functional nanomaterials in the therapy of rheumatoid arthritis and tumors by manipulating SPARC as a new target. This article provides ideas for using functional nanomaterials to treat inflammatory diseases through the SPARC target. The purpose of this article is to provide a reference for ongoing disease research based on SPARC-targeted therapy.

The Matricellular Protein Hevin Is Involved in Alcohol Use Disorder

Astrocytic-secreted matricellular proteins have been shown to influence various aspects of synaptic function. More recently, they have been found altered in animal models of psychiatric disorders such as drug addiction. Hevin (also known as Sparc-like 1) is a matricellular protein highly expressed in the adult brain that has been implicated in resilience to stress, suggesting a role in motivated behaviors. To address the possible role of hevin in drug addiction, we quantified its expression in human postmortem brains and in animal models of alcohol abuse. Hevin mRNA and protein expression were analyzed in the postmortem human brain of subjects with an antemortem diagnosis of alcohol use disorder (AUD, n = 25) and controls (n = 25). All the studied brain regions (prefrontal cortex, hippocampus, caudate nucleus and cerebellum) in AUD subjects showed an increase in hevin levels either at mRNA or/and protein levels. To test if this alteration was the result of alcohol exposure or indicative of a susceptibility factor to alcohol consumption, mice were exposed to different regimens of intraperitoneal alcohol administration. Hevin protein expression was increased in the nucleus accumbens after withdrawal followed by a ethanol challenge. The role of hevin in AUD was determined using an RNA interference strategy to downregulate hevin expression in nucleus accumbens astrocytes, which led to increased ethanol consumption. Additionally, ethanol challenge after withdrawal increased hevin levels in blood plasma. Altogether, these results support a novel role for hevin in the neurobiology of AUD.

Immunological role and prognostic value of SPARCL1 in pan-cancer analysis

Background: Secreted protein acidic and rich in cysteine-like 1 (SPARCL1) was a kind of extracellular matrix glycoprotein. SPARCL1 was strongly inhibited in most cancers. However, the potential functions of SPARCL1 in the pan-cancer cohort have not been widely studied. Methods: We evaluated the transcriptional level and the prognostic value of SPARCL1 in 33 types of cancer and revealed the relationship between genetic alterations of SPARCL1 and the tumor mutation burden. Meanwhile, we assessed the correlations between SPARCL1 and tumor-infiltrating lymphocytes across cancers. Results: The transcriptional level of SPARCL1 was inhibited in most cancers. Although SPARCL1 was down-regulated in most cancers, SPARCL1 might play a protective or detrimental role in different cancers. We demonstrated that mutation count was elevated in the altered SPARCL1 group in several cancers. Additionally, we found a significant positive correlation between SPARCL1 and macrophage infiltration levels in most cancers. Especially, marker sets of M2 macrophages were strongly related to SPARCL1 in cholangiocarcinoma, colon adenocarcinoma, rectum adenocarcinoma, and pancreatic adenocarcinoma. Conclusion: Our study found that SPARCL1 might work as a biomarker for prognosis and immune infiltration in pan-cancer analysis.

Circular_0086414 induces SPARC like 1 (SPARCL1) production to inhibit esophageal cancer cell proliferation, invasion and glycolysis and induce cell apoptosis by sponging miR-1290

Circular RNA (circRNA) plays an important role in cancer progression. Here, we investigated the function of circ_0086414 in the malignant progression of esophageal cancer (EC). RNA expression of circ_0086414, microRNA-1290 (miR-1290), and SPARC like 1 (SPARCL1) was detected by quantitative real-time polymerase chain reaction. The protein levels of N-cadherin, E-cadherin, and SPARCL1 were checked by Western blotting analysis. Cell proliferation was investigated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 5-Ethynyl-29-deoxyuridine (EdU), and cell colony formation assays. Cell invasion and apoptosis were analyzed by transwell invasion assay and flow cytometry analysis, respectively. Glycolysis was evaluated by analyzing glucose consumption and lactate production. In an xenograft mouse model, the effect of circ_0086414 on tumor tumorigenesis was investigated. The interactions among circ_0086414, miR-1290, and SPARCL1 were identified by dual-luciferase reporter and RNA pull-down assays. Results showed that circ_0086414 and SPARCL1 expression were significantly downregulated, while miR-1290 was upregulated in EC tissues and cells. EC patients with low circ_0086414 expression had a poor prognosis. Increasing circ_0086414 expression led to decreased EC cell proliferation, invasion and glycolysis and increased cell apoptosis, accompanied by a decrease of N-cadherin expression and an increase of E-cadherin expression. Also, the enforced expression of circ_0086414 delayed tumor tumorigenesis. Besides, circ_0086414 acted as a miR-1290 sponge and regulated EC cell processes by binding to the miRNA. MiR-1290 also participated in EC malignant progression through SPARCL1. Further, circ_0086414 stimulated SPARCL1 production by negatively regulating miR-1290. Thus, circ_0086414 inhibited EC cell malignancy through the miR-1290/SPARCL1 pathway, providing a reliable target for the therapy of EC.

Prognostic Significance of SPARC Expression in Breast Cancer: A Meta-Analysis and Bioinformatics Analysis

Secreted protein, acidic and rich in cysteine (SPARC, also known as osteonectin), is a small molecule glycoprotein associated with cell secretions. The purpose of our research is to clarify the clinicopathological and prognostic significance of SPARC expression in breast cancer. In this study, we performed a meta-analysis and bioinformatics analysis using the PubMed, Web of Science, Wanfang Data, and CNKI databases. The meta-analysis showed that SPARC expression was elevated in breast cancer tissue, compared with normal tissue, while SPARC expression in tumor stromal cells was higher than that of tumor cells. The expression of SPARC was positively correlated with histological grade and TNM staging. The Kaplan-Meier plotter showed that low SPARC expression was negatively correlated with the overall, postprogression, and distant metastasis survival rates of patients. According to Oncomine database, SPARC expression was upregulated in breast cancer than normal tissues. In TCGA database, univariate analysis showed that lymph node metastasis, distant metastasis, and TNM staging were negatively correlated with patient prognosis in breast cancers. Cox multivariate analysis showed that age, lymph node metastasis, distant metastasis, and TNM staging were important factors affecting the survival time of breast cancer patients. SPARC expression can be employed as a good indicator of prognosis of breast cancer patients, which will provide new methods and ideas of preventive treatment.

SPARCL1 Is a Novel Prognostic Biomarker and Correlates with Tumor Microenvironment in Colorectal Cancer

Background

Secreted protein acidic and rich in cysteine-like 1 (SPARCL1) plays an important role in tumor pathogenesis. We aim to evaluate the clinical significance and potential biological roles of SPARCL1 in colorectal cancer (CRC).

Methods

Datasets from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were downloaded to evaluate the expression levels of SPARCL1 in CRC. Receiver operating characteristic (ROC) curve was constructed to evaluate the diagnostic value of SPARCL1. Then, comprehensive database search was conducted for published clinical studies to explore clinical significance of SPARCL1. In addition, coexpression genes of SPARCL1 were identified through the cBioPortal database and enrichment analysis of SPARCL1 and its coexpression genes were performed by the “clusterProfiler” R package. Finally, the correlations between SPARCL1 and tumor microenvironment scores, tumor-infiltrating immune cells in CRC were determined by “ESTIMATE” and “GSVA” R packages.

Results

SPARCL1 was significantly downregulated in CRC tissues, and SPARCL1 showed high accuracy for diagnosis of primary CRC in both GEO and TCGA datasets. Pooled results from published clinical studies showed SPARCL1 expression was associated with differentiation (OR = 1.89, 95% CI: 1.38-2.59), tumor stage (OR = 0.47, 95% CI: 0.29-0.77), distant metastasis (OR = 0.53, 95% CI: 0.33-0.84), and overall survival (HR = 0.56, 95% CI: 0.43-0.74). SPARCL1 and its top 300 coexpression genes were involved in several KEGG pathways, such as focal adhesion, cell adhesion molecules, PI3K-Akt signaling pathway, cGMP-PKG signaling pathway, and ECM-receptor interaction. Besides, the SPARCL1 expression was significantly correlated with stromal score, immune score, ESTIMATE score, and diverse immune cells.

Conclusion

SPARCL1 significantly correlated with clinicopathological features and tumor microenvironment in CRC.

A 10-Gene Signature Identified by Machine Learning for Predicting the Response to Transarterial Chemoembolization in Patients with Hepatocellular Carcinoma

Background

Transarterial chemoembolization (TACE) is recommended for intermediate-stage HCC patients. Owing to substantial variation in its efficacy, indicators of patient responses to TACE need to be determined.

Methods

A Gene Expression Omnibus (GEO) dataset consisting of patients of different TACE-response status was retrieved. Differentially expressed genes (DEGs) were calculated and variable gene ontology analyses were conducted. Potential drugs and response to immunotherapy were predicted using multiple bioinformatic algorithms. We built and compared 5 machine-learning models with finite genes to predict patients' response to TACE. The model was also externally validated to discern different survival outcomes after TACE. Tumor-infiltrating lymphocytes (TILs) and tumor stemness index were evaluated to explore potential mechanism of our model.

Results

The gene set variation analysis revealed enhanced pathways related to G2/M checkpoint, E2F, mTORC1, and myc in TACE nonresponders. TACE responders had better immunotherapy response too. 373 DEGs were detected and the upregulated DEGs in nonresponders were enriched in IL-17 signal pathway. 5 machine-learning models were constructed and evaluated, and a linear support vector machine (SVM)-based model with 10 genes was selected (AQP1, FABP4, HERC6, LOX, PEG10, S100A8, SPARCL1, TIAM1, TSPAN8, and TYRO3). The model achieved an AUC and accuracy of 0.944 and 0.844, respectively, in the development cohort. In the external validation cohort comprised of patients receiving adjuvant TACE and postrecurrence TACE treatment, the predicted response group significantly outlived the predicted nonresponse counterparts. TACE nonresponders tend to have more macrophage M0 cells and lower resting mast cells in the tumor tissue and the stemness index is also higher than responders. Those characteristics were successfully captured by our model.

Conclusion

The model based on expression data of 10 genes could potentially predict HCC patients' response and prognosis after TACE treatment. The discriminating power was TACE-specific.

Association of serum secreted protein acidic and rich in cysteine-like protein 1 with metabolic measures and dyslipidemia among Chinese adults

OBJECTIVES

Recent studies found that secreted protein acidic and rich in cysteine-like protein 1 (Sparcl1) could inhibit lipid droplets accumulation by peroxisome proliferator-activated receptor-gamma (PPARγ) signal pathway. However, the associations of serum Sparcl1 level with lipids profiles and other metabolic phenotypes remain unknown in human population study.

METHODS

We determined serum Sparcl1 using sandwich enzyme-linked immunosorbent assays among 1750 adults aged 40 years and older from a community in Shanghai, China. Generalized linear regression models were used to evaluate the association between Sparcl1 and metabolic measures. Multivariable-adjusted logistic regression analyses were performed to evaluate the relationship of serum Sparcl1 with prevalent dyslipidemia.

RESULTS

With the increment of serum Sparcl1, participants tended to have lower level of triglycerides, and higher level of high-density lipoprotein cholesterol (all P for trend < 0.01). No significant associations between serum Sparcl1 and glucose, blood pressure, or body size were observed. The generalized linear regression models suggested that per standard deviation (SD) increment of serum Sparcl1 was significantly inversely associated with triglycerides (β= -0.06, P=0.02). The prevalence of dyslipidemia decreased across the sparcl1 quartiles (P for trend <0.01). After controlling the potential confounders, participants in the highest quartile of sparcl1 concentration had the lowest prevalence of dyslipidemia (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.52-0.91), compared with the lowest quartile. Per SD increment of Sparcl1 was associated with 20% (OR, 0.80; 95%CI, 0.69-0.94) lower prevalence of hypertriglyceridemia and 12% (OR, 0.88; 95%CI, 0.79-0.97) lower prevalence of dyslipidemia. The association between serum Sparcl1 and dyslipidemia were generally consistent across subgroups (all P for interaction > 0.05).

CONCLUSION

Serum Sparcl1 was significantly associated with decreased risk of prevalent dyslipidemia in Chinese population. Further studies are warranted to confirm this association.

Immunomodulatory Role of the Extracellular Matrix Within the Liver Disease Microenvironment

Chronic liver disease when accompanied by underlying fibrosis, is characterized by an accumulation of extracellular matrix (ECM) proteins and chronic inflammation. Although traditionally considered as a passive and largely architectural structure, the ECM is now being recognized as a source of potent damage-associated molecular pattern (DAMP)s with immune-active peptides and domains. In parallel, the ECM anchors a range of cytokines, chemokines and growth factors, all of which are capable of modulating immune responses. A growing body of evidence shows that ECM proteins themselves are capable of modulating immunity either directly via ligation with immune cell receptors including integrins and TLRs, or indirectly through release of immunoactive molecules such as cytokines which are stored within the ECM structure. Notably, ECM deposition and remodeling during injury and fibrosis can result in release or formation of ECM-DAMPs within the tissue, which can promote local inflammatory immune response and chemotactic immune cell recruitment and inflammation. It is well described that the ECM and immune response are interlinked and mutually participate in driving fibrosis, although their precise interactions in the context of chronic liver disease are poorly understood. This review aims to describe the known pro-/anti-inflammatory and fibrogenic properties of ECM proteins and DAMPs, with particular reference to the immunomodulatory properties of the ECM in the context of chronic liver disease. Finally, we discuss the importance of developing novel biotechnological platforms based on decellularized ECM-scaffolds, which provide opportunities to directly explore liver ECM-immune cell interactions in greater detail.

SPARC-p53: The double agents of cancer

Cancer is a complex disease with high incidence and mortality rates. The important role played by the tumor microenvironment in regulating oncogenesis, tumor growth, and metastasis is by now well accepted in the scientific community. SPARC is known to participate in tumor-stromal interactions and impact cancer growth in ambiguous ways, which either enhance or suppress cancer aggressiveness, in a context-dependent manner. p53 transcription factor, a well-established tumor suppressor, has been reported to promote tumor growth in certain situations, such as hypoxia, thus displaying a duality in its action. Although both proteins are being tested in clinical trials, the synergistic relation between them is yet to be explored in clinical practice. In this review, we address the controversial roles of SPARC and p53 as double agents in cancer, briefly summarizing the interaction found between these two molecules and its importance in cancer.

Secreted protein acidic and rich in cysteine gene variants: Impact on susceptibility and survival of hepatocellular carcinoma patients

BACKGROUND AND AIM

Secreted protein acidic and rich in cysteine (SPARC) is a glycoprotein involved in extracellular matrix remodeling, which regulates cell growth. It could be involved in hepatic fibrogenesis related to chronic inflammations, hepatocellular carcinoma (HCC) angiogenesis, and tumor progression. We aimed to study the expressions of single nucleotide polymorphisms in the SPARC gene and their impact on susceptibility and survival of HCC patients.

METHODS

We conducted a case-control study on 200 HCC patients and 50 matched healthy controls. All patients were subjected to laboratory investigations, ultrasound, and real-time polymerase chain reaction to detect the genetic polymorphisms (rs3210714, rs11950384, and rs7719521) in the SPARC gene in the blood.

RESULTS

One hundred sixty (80%) patients were men with a mean age of 43 years. The SPARC gene showed a significant higher prevalence of rs3210714 mutation (i.e. AA or AG) and a significant lower prevalence of rs11950384 mutation (i.e. AA or AC) among HCC patients in comparison with controls (83% vs 22%, P ≤ 0.001) and (65.5 vs 86%, P = 0.005), respectively, while rs7719521 mutation did not reach significance. On univariate and multivariate analyses, elder age and having at least one copy of the mutant rs3210714 were associated with a significantly increased risk of HCC (P < 0.001 for both), whereas the presence of at least one copy of the mutant rs11950384 carried a significantly reduced risk of having HCC (P < 0.01). Overall survival did not differ significantly between any of the SPARC gene mutation groups.

CONCLUSIONS

The SPARC gene polymorphisms had a diverse impact on the susceptibility of HCC due to its ability to inhibit or promote tumor progression. SPARC gene polymorphisms were not related to survival of our HCC patients, and probably, this needs further analysis of other SPARC gene nucleotides.

Roles of Albumin-Binding Proteins in Cancer Progression and Biomimetic Targeted Drug Delivery

Nutrient transporters have attracted significant attention for their promising application in biomimetic delivery. Due to the active consumption of nutrients, cancer cells generally overexpress nutrient transporters to meet their increased need for energy and materials. For example, albumin-binding proteins (ABPs) are highly overexpressed in malignant cells, stromal cells, and tumor vessel endothelial cells responsible for albumin uptake. ABP (e.g., SPARC) is a promising target for tumor-specific drug delivery, and albumin has been widely used as a biomimetic delivery carrier. Apart from the transportation function, ABPs are closely associated with neoplasia, invasion, and metastasis. Herein, a summary of the roles of ABP in cancer progression and the application of albumin-based biomimetic tumor-targeted delivery through the ABP pathway is presented.

Identification of key pathways and biomarkers in sorafenib-resistant hepatocellular carcinoma using bioinformatics analysis

Hepatocellular carcinoma (HCC) is one of the most common malignant types of cancer, with a high mortality rate. Sorafenib is the sole approved oral clinical therapy against advanced HCC. However, individual patients exhibit varying responses to sorafenib and the development of sorafenib resistance has been a new challenge for its clinical efficacy. The current study identified gene biomarkers and key pathways in sorafenib-resistant HCC using bioinformatics analysis. Gene dataset GSE73571 was obtained from the Gene Expression Omnibus (GEO) database, including four sorafenib-acquired resistant and three sorafenib-sensitive HCC phenotypes. Differentially expressed genes (DEGs) were identified using the web tool GEO2R. Functional and pathway enrichment of DEGs were analyzed using the Database for Annotation, Visualization and Integrated Discovery and the protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins and Cytoscape. A total of 1,319 DEGs were selected, which included 593 upregulated and 726 downregulated genes. Functional and pathway enrichment analysis revealed DEGs enriched in negative regulation of endopeptidase activity, cholesterol homeostasis, DNA replication and repair, coagulation cascades, insulin resistance, RNA transport, cell cycle and others. Eight hub genes, including kininogen 1, vascular cell adhesion molecule 1, apolipoprotein C3, alpha 2-HS glycoprotein, erb-b2 receptor tyrosine kinase 2, secreted protein acidic and cysteine rich, vitronectin and vimentin were identified from the PPI network. In conclusion, the present study identified DEGs and key genes in sorafenib-resistant HCC, which further the knowledge of potential mechanisms in the development of sorafenib resistance and may provide potential targets for early diagnosis and new treatments for sorafenib-resistant HCC.

Secreted protein acidic and rich in cysteine-like 1 suppresses metastasis in gastric stromal tumors

Background

Malignant growth and metastasis of gastrointestinal stromal tumors (GIST) occur in some patients even during the course of treatment, but their mechanisms remains poorly understand at the molecular level so far.

Methods

Profiles of protein expression in gastric GIST tissues were explored using protein microarray analysis, down-regulation of SPARCL1 (secreted protein acidic and rich in cysteine-like protein 1) was validated by RT-qPCR, western blot and immunohistochemistry. The effect of specific shRNA-induced SPARCL1 downregulation on the biological traits of GIST 882 cell was investigated. We then employed a mouse xenograft model to investigate whether the low-expression of SPARCL1 impact the metastasis ability of GIST cells in vivo.

Results

SPARCL1 was significantly downregulated in the gastric GIST with high-grade malignance as compared with low-grade malignance, its expression was closely correlated with tumor size, mitotic index, distant metastasis at the time of initial diagnosis and tumor progression of GIST (P < 0.05). Moreover, results of the Cox analysis showed that expression of SPARCL1 is an independent prognostic predictors for gastric GIST (P = 0.008; HR 0.157, 95% CI 0.040~ 0.612). Downregulation of SPARCL1 promoted cell migration and invasion, but did not affect proliferation, cell cycle and apoptosis of GIST 882 cells. In mouse xenograft model, GIST cells with the decreased expression of SPARCL1 presented an enhanced ability of liver metastasis (P < 0.05).

Conclusions

Taken together, our present study demonstrated that SPARCL1 have a certain degree of malignancy-suppressing potential through inhibiting the metastasis of gastric GIST.

Electronic supplementary material

The online version of this article (10.1186/s12876-018-0833-8) contains supplementary material, which is available to authorized users.

A temporal examination of calcium signaling in cancer- from tumorigenesis, to immune evasion, and metastasis

Background

Although the study of calcium (Ca²⁺) is classically associated with excitable cells such as myocytes or neurons, the ubiquity of this essential element in all cellular processes has led to interest in other cell types. The importance of Ca²⁺ to apoptosis, cell signaling, and immune activation is of special import in cancer.

Main

Here we review the current understanding of Ca²⁺ in each of these processes vital to the initiation, spread, and drug resistance of malignancies. We describe the involvement of Ca²⁺, and Ca²⁺ related proteins in cell cycle checkpoints and Ca²⁺ dependent apoptosis and discuss their roles in cellular immortalization. The role of Ca²⁺ in inter-cellular communication is also discussed in relevance to tumor-stromal communication, angiogenesis, and tumor microinvasion. The role that Ca²⁺ plays in immune surveillance and evasion is also addressed. Finally, we discuss the possibility of targeting Ca²⁺ singling to address the most pressing topics of cancer treatment: metastatic disease and drug resistance.

Conclusion

This review discusses the current understanding of Ca²⁺ in cancer. By addressing Ca²⁺ facilitated angiogenesis, immune evasion, metastasis, and drug resistance, we anticipate future avenues for development of Ca²⁺ as a nexus of therapy.

Prognostic value of SPARCL1 in patients with colorectal cancer

Secreted protein acidic and rich in cysteine-like 1 (SPARCL1), a member of extracelluar matrix glycoprotein, has been reported to be associated with various tumor types. The present study aimed to evaluate the prognostic value of SPARCL1 in patients with colorectal cancer. Tissue microarray blocks were constructed based on 79 patients who underwent radical surgery at the Kunshan First People's Hospital between 2008 and 2010. Thirty pairs of fresh-frozen tissues were also obtained for total protein extraction. The expression of SPARCL1 protein was analyzed using immunohistochemistry and western blotting analyses, and the association between overexpressed SPARCL1 and clinicopathological factors was evaluated. Survival analysis with Kaplan Meier curves and Cox regression analysis was used to analyze the prognostic value of SPARCL1. According to western blot analyses, SPARCL1 protein expression in colorectal tumors was significantly lower compared with corresponding normal tissues. The expression of SPARCL1 was markedly decreased from differentiation I to III, and the negative rate of SPARCL1 was higher at Duke's stage C compared with B. Though without any difference between ‘positive’ and ‘negative’ in overall survival, significantly higher survival in patients with positive SPARCL1 expression at Duke's stage B was detected in the present study. These results indicated that SPARCL1 may be a potential tumor suppressor gene and associated with good prognosis.

In-depth proteomic analysis of tissue interstitial fluid for hepatocellular carcinoma serum biomarker discovery

Background:

Hepatocellular carcinoma (HCC) is a primary malignancy of the liver. New serum biomarkers for HCC screening are needed, especially for alpha-fetoprotein (AFP) negative patients. As a proximal fluid between body fluids and intracellular fluid, tissue interstitial fluid (TIF) is a suitable source for serum biomarker discovery.

Methods:

Sixteen paired TIF samples from HCC tumour and adjacent non-tumour tissues were analysed by isobaric tags for relative and absolute quantitation (iTRAQ) method. Two proteins were selected for ELISA validation in serum samples.

Results:

Totally, 3629 proteins were identified and 3357 proteins were quantified in TIF samples. Among them, 232 proteins were significantly upregulated in HCC-TIF and 257 proteins down-regulated. Two overexpressed extracellular matrix proteins, SPARC and thrombospondin-2 (THBS2) were selected for further validation. ELISA result showed that the serum levels of SPARC and THBS2 in HCC patients were both significantly higher than those in healthy controls. The combination of serum SPARC and THBS2 could distinguish HCC (AUC=0.97, sensitivity=86%, specificity=100%) or AFP-negative HCC (AUC=0.95, sensitivity=91%, specificity=93%) from healthy controls. And the combination of serum SPARC and THBS2 could also distinguish HCC patients from benign liver disease patients (AUC=0.93, sensitivity=80%, specificity=94%). In addition, serum THBS2 was found to be a novel independent indicator for poor prognosis of HCC.

Conclusions:

Novel HCC candidate serum markers were found through in-depth proteomic analysis of TIF, which demonstrated the successful utility of TIF in cancer serum biomarker discovery.

Associations of tumor suppressor SPARCL1 with cancer progression and prognosis

SPARC-like protein 1 (SPARCL1), a member of the family of secreted proteins which is acidic and rich in cysteine, is a potential tumor suppressor gene in most types of tumor. A systemic review and bioinformatics analysis was carried out to determine the associations between SPARCL1 and tumor progression and clinical factors. Downregulation of SPARCL1, thought to be regulated by epigenetic modifications including DNA methylation, serves important functions in tumor progression and development, with its regulatory functions on cell viability, migration, invasion, cell adhesion and drug resistance. Downregulation of SPARCL1 was markedly associated with a poor overall survival rate of patients with one of ≥7 solid tumors and predicted increased mortality in patients with one of ≥4 distinct tumor types. The present review indicated that SPARCL1 may be a therapeutic target for cancer treatment and a biomarker to determine prognosis.

A holistic approach to dissecting SPARC family protein complexity reveals FSTL-1 as an inhibitor of pancreatic cancer cell growth

SPARC is a matricellular protein that is involved in both pancreatic cancer and diabetes. It belongs to a wider family of proteins that share structural and functional similarities. Relatively little is known about this extended family, but evidence of regulatory interactions suggests the importance of a holistic approach to their study. We show that Hevin, SPOCKs, and SMOCs are strongly expressed within islets, ducts, and blood vessels, suggesting important roles for these proteins in the normal pancreas, while FSTL-1 expression is localised to the stromal compartment reminiscent of SPARC. In direct contrast to SPARC, however, FSTL-1 expression is reduced in pancreatic cancer. Consistent with this, FSTL-1 inhibited pancreatic cancer cell proliferation. The complexity of SPARC family proteins is further revealed by the detection of multiple cell-type specific isoforms that arise due to a combination of post-translational modification and alternative splicing. Identification of splice variants lacking a signal peptide suggests the existence of novel intracellular isoforms. This study underlines the importance of addressing the complexity of the SPARC family and provides a new framework to explain their controversial and contradictory effects. We also demonstrate for the first time that FSTL-1 suppresses pancreatic cancer cell growth.

MiRNA-211 suppresses cell proliferation, migration and invasion by targeting SPARC in human hepatocellular carcinoma

Previous studies have shown that the expression of miR-211 was downregulated in hepatocellular carcinoma (HCC). However, the molecular function and mechanism of miR-211 in HCC growth and invasion are largely unclear. We found that miR-211 is downregulated in HCC tissues and cell lines, respectively. Further results showed that low miR-211 associated with TNM stage, vein invasion status, and poor prognosis. Ectopic expression of miR-211 effectively suppressed HCC cell proliferation, migration and invasion both in vitro and in vivo. We identified SPARC as a bona fide target of miR-211, and overexpression of miR-211 decreased the mRNA and protein expression of SPARC. Finally, we confirmed that the overexpression of SPARC in miR-211-expressing HCC cells can partially restore the inhibitory effect of miR-211. Taken together, our results demonstrated that loss of miR-211 expression and thus uncontrolled SPARC overexpression might drive progression of HCC, which may provide a novel therapeutic strategy for the treatment of HCC.

SPARCL1 expression increases with preoperative radiation therapy and predicts better survival in rectal cancer patients

PURPOSE

The secreted protein acidic and rich in cysteine-like 1 (SPARCL1) is expressed in various normal tissues and many types of cancers. The function of SPARCL1 and its relationship to a patient's prognosis have been studied, whereas its relationship to radiation therapy (RT) is not known. Our aim was to investigate the expression of SPARCL1 in rectal cancer patients who participated in a clinical trial of preoperative RT.

METHODS AND MATERIALS

The study included 136 rectal cancer patients who were randomized to undergo preoperative RT and surgery (n=63) or surgery alone (n=73). The expression levels of SPARCL1 in normal mucosa (n=29), primary tumor (n=136), and lymph node metastasis (n=35) were determined by immunohistochemistry.

RESULTS

Tumors with RT had stronger SPARCL1 expression than tumors without RT (P=.003). In the RT group, strong SPARCL1 expression was related to better survival than weak expression in patients with stage III tumors, independent of sex, age, differentiation, and margin status (P=.022; RR = 18.128; 95% confidence interval, 1.512-217.413). No such relationship was found in the non-RT group (P=.224). Further analysis of interactions among SPARCL1 expression, RT, and survival showed statistical significance (P=.024). In patients with metastases who received RT, strong SPARCL1 expression was related to better survival compared to weak expression (P=.041) but not in the non-RT group (P=.569).

CONCLUSIONS

SPARCL1 expression increases with RT and is related to better prognosis in rectal cancer patients with RT but not in patients without RT. This result may help us to select the patients best suited for preoperative RT.

SPARC expression is negatively correlated with clinicopathological factors of gastric cancer and inhibits malignancy of gastric cancer cells

Secreted protein acidic and rich in cysteine (SPARC) is a glycoprotein which plays multiple roles in different types of cancer. Our previous study showed that SPARC overexpression inhibited the growth and angiogenesis of tumors, and reduced expression of vascular endothelial growth factor (VEGF). However, the relationship between SPARC expression and clinicopathological factors of gastric cancer (GC) is controversial, and the role of SPARC in GC remains unclear. We evaluated expression of SPARC in 65 human GC tissues using immunohistochemistry (IHC). The results indicated that SPARC expression was negatively correlated with clinicopathological factors of GC. In vitro assay showed that SPARC overexpression decreased proliferation and clonogenicity by suppressing CD44 expression. In addition, SPARC overexpression inhibited VEGF induced proliferation and arrested cell cycle of GC cells by reducing the activation of VEGFR2, ERK1/2 and AKT signaling pathways. SPARC suppressed the invasion and migration of GC by reducing MMP-7, MMP-9, N-cadherin, Sp1 and p-ERK1/2 expression. In the in vivo assay, cancer metastasis mouse models were established by tail vein injection. The results revealed that the lung metastases of SPARC-overexpressing GC cells in the mice were much fewer than those of control cells.

Insidious changes in stromal matrix fuel cancer progression

Reciprocal interactions between tumor and stromal cells propel cancer progression and metastasis. A complete understanding of the complex contributions of the tumor stroma to cancer progression necessitates a careful examination of the extracellular matrix (ECM), which is largely synthesized and modulated by cancer-associated fibroblasts. This structurally supportive meshwork serves as a signaling scaffold for a myriad of biologic processes and responses favoring tumor progression. The ECM is a repository for growth factors and cytokines that promote tumor growth, proliferation, and metastasis through diverse interactions with soluble and insoluble ECM components. Growth factors activated by proteases are involved in the initiation of cell signaling pathways essential to invasion and survival. Various transmembrane proteins produced by the cancer stroma bind the collagen and fibronectin-rich matrix to induce proliferation, adhesion, and migration of cancer cells, as well as protease activation. Integrins are critical liaisons between tumor cells and the surrounding stroma, and with their mechano-sensing ability, induce cell signaling pathways associated with contractility and migration. Proteoglycans also bind and interact with various matrix proteins in the tumor microenvironment to promote cancer progression. Together, these components function to mediate cross-talk between tumor cells and fibroblasts ultimately to promote tumor survival and metastasis. These stromal factors, which may be expressed differentially according to cancer stage, have prognostic utility and potential. This review examines changes in the ECM of cancer-associated fibroblasts induced through carcinogenesis, and the impact of these changes on cancer progression. The implication is that cancer progression, even in epithelial cancers, may be based in large part on changes in signaling from cancer-associated stromal cells. These changes may provide early prognostic indicators to further stratify patients during treatment or alter the timing of their follow-up visits and observations.

Clinical significance of SPARC gene expression in patients with gastric cancer

PURPOSE

Secreted protein acidic and rich in cysteine (SPARC) is one of the first known matricellular proteins that modulates interactions between cells and extracellular matrix. Recent studies investigated the clinical significance of SPARC gene expression in the development, progression, and metastasis of cancer. The present study examined the relations of the relative expression of the SPARC gene to clinicopathological factors and overall survival in patients with gastric cancer.

METHODS

We studied surgical specimens of cancer tissue and adjacent normal mucosa obtained from 227 patients with previously untreated gastric cancer. The relative expression levels of SPARC mRNA in cancer tissue and in adjacent normal mucosa were measured by quantitative real-time, reverse-transcription polymerase chain reaction.

RESULTS

The relative expression level of the SPARC gene was higher in cancer tissue than in adjacent normal mucosa. High expression levels of the SPARC gene were related to serosal invasion (P = 0.046). Overall survival at 5 years differed significantly between patients with high SPARC gene expression and those with low expression (P = 0.006).

CONCLUSIONS

Overexpression of the SPARC gene may be a useful independent predictor of outcomes in patients with gastric cancer.

nab-Paclitaxel mechanisms of action and delivery

Taxanes are a key chemotherapy component for several malignancies, including metastatic breast cancer (MBC), ovarian cancer, and advanced non-small cell lung cancer (NSCLC). Despite the clinical benefit achieved with solvent-based (sb) taxanes, these agents can be associated with significant and severe toxicities. Albumin-bound paclitaxel (Abraxane; nab®-Paclitaxel), a novel solvent-free taxane, has demonstrated higher response rates and improved tolerability when compared with solvent-based formulations in patients with advanced MBC and NSCLC. The technology used to create nab-paclitaxel utilizes albumin to deliver paclitaxel, resulting in an advantageous pharmacokinetic (PK) profile. This review discusses the proposed mechanism of delivery of nab-paclitaxel, including an examination into a hypothesized greater ability to leverage albumin-based transport relative to sb-paclitaxel. An advantageous PK profile and the more efficient use of albumin-based transport may contribute to the preclinical finding that nab-paclitaxel achieves a 33% higher tumor uptake relative to sb-paclitaxel. Another possible contributing factor to the tumor accumulation of nab-paclitaxel is the binding of albumin to secreted protein acidic and rich in cysteine (SPARC), although the data supporting this relationship between SPARC and nab-paclitaxel remain largely correlative at this point. Recent data also suggest that nab-paclitaxel may enhance tumor accumulation of gemcitabine in pancreatic cancer treated with both agents. Additionally, a possible mechanistic synergy between nab-paclitaxel and capecitabine has been cited as the rationale to combine the two agents for MBC treatment. Thus, nab-paclitaxel appears to interact with tumors in a number of interesting, but not fully understood, ways. Continued preclinical and clinical research across a range of tumor types is warranted to answer the questions that remain on the mechanisms of delivery and antitumor activity of nab-paclitaxel.

Progress in understanding role of SPARC protein in gastric cancer

SPARC is a cysteine-rich secretory protein that is highly conservative and shares >70% amino acid sequence homology across all kinds of living organisms. The single-copy gene encoding the SPARC protein is located on human chromosome 5q31.3-q32, consists of 10 exons, and has a full length of 25 900 bp. SPARC protein is mainly expressed in tissue repair-related fibroblasts and endothelial cells, and high expression of SPARC protein has been noted in some aggressive malignant tumors. The incidence and mortality of gastric cancer are high in China, and the high mortality is closely related with tumor invasion and metastasis. SPARC protein is abnormally expressed in gastric carcinoma, and there is still controversy over the role of SPARC in gastric carcinoma. In this paper we review recent progress in understanding the role of SPARC protein in gastric cancer.

Lack of the matricellular protein SPARC (secreted protein, acidic and rich in cysteine) attenuates liver fibrogenesis in mice

Introduction

Secreted Protein, Acidic and Rich in Cysteine (SPARC) is a matricellular protein involved in many biological processes and found over-expressed in cirrhotic livers. By mean of a genetic approach we herein provide evidence from different in vivo liver disease models suggesting a profibrogenic role for SPARC.

Methods

Two in vivo models of liver fibrosis, based on TAA administration and bile duct ligation, were developed on SPARC wild-type (SPARC^+/+) and knock-out (SPARC^−/−) mice. Hepatic SPARC expression was analyzed by qPCR. Fibrosis was assessed by Sirius Red staining, and the maturation state of collagen fibers was analyzed using polarized light. Necroinflammatory activity was evaluated by applying the Knodell score and liver inflammatory infiltration was characterized by immunohistochemistry. Hepatic stellate cell activation was assessed by α-SMA immunohistochemistry. In addition, pro-fibrogenic genes and inflammatory cytokines were measured by qPCR and/or ELISA. Liver gene expression profile was analyzed in SPARC^−/− and SPARC^+/+ mice using Affymetrix Mouse Gene ST 1.0 array.

Results

SPARC expression was found induced in fibrotic livers of mouse and human. SPARC^−/− mice showed a reduction in the degree of inflammation, mainly CD4+ cells, and fibrosis. Consistently, collagen deposits and mRNA expression levels were decreased in SPARC^−/− mice when compared to SPARC^+/+ mice; in addition, MMP-2 expression was increased in SPARC^−/− mice. A reduction in the number of activated myofibroblasts was observed. Moreover, TGF-β1 expression levels were down-regulated in the liver as well as in the serum of TAA-treated knock-out animals. Ingenuity Pathway Analysis (IPA) analysis suggested several gene networks which might involve protective mechanisms of SPARC deficiency against liver fibrogenesis and a better established machinery to repair DNA and detoxify from external chemical stimuli.

Conclusions

Overall our data suggest that SPARC plays a significant role in liver fibrogenesis. Interventions to inhibit SPARC expression are suggested as promising approaches for liver fibrosis treatment.

Targeting SPARC by lentivirus-mediated RNA interference inhibits cervical cancer cell growth and metastasis

Background

Secreted protein acidic and rich in cysteine (SPARC), a calcium-binding matricellular glycoprotein, is implicated in the progressions of some cancers. However, no information has been available to date regarding the function of SPARC in cervical cancer cell growth and metastasis.

Methods

In this study, we isolated and established high invasive subclones and low invasive subclones from human cervical cancer cell lines HeLa and SiHa by the limited dilution method. Real-time q-RT-PCR, Western Blot and ICC were performed to investigate SPARC mRNA and protein expressions in high invasive subclones and low invasive subclones. Then lentivirus vector with SPARC shRNA was constructed and infected the highly invasive subclones. Real-time q-RT-PCR, Western Blot and ICC were also performed to investigate the changes of SPARC expression after viral infection. In functional assays, effects of SPARC knockdown on the biological behaviors of cervical cancer cells were investigated. The mechanisms of SPARC in cervical cancer proliferation, apoptosis and invasion were also researched.

Results

SPARC was over-expressed in the highly invasive subclones compared with the low invasive subclones. Knockdown of SPARC significantly suppressed cervical cancer cell proliferation, and induced cell cycle arrest at the G1/G0 phase through the p53/p21 pathway, also caused cell apoptosis accompanied by the decreased ratio of Bcl-2/Bax, and inhibited cell invasion and metastasis accompanied by down-regulated MMP2 and MMP9 expressions and up-regulated E-cadherin expression.

Conclusion

SPARC is related to the invasive phenotype of cervical cancer cells. Knockdown of SPARC significantly suppresses cervical cancer cell proliferation, induces cell apoptosis and inhibits cell invasion and metastasis. SPARC as a promoter improves cervical cancer cell growth and metastasis.

microRNA-29a suppresses cell proliferation by targeting SPARC in hepatocellular carcinoma

In the present study, we constructed a lentivirus vector encoding the miR-29a precursor and established two stably infected cell lines, PLC-29a and 97L-29a. The overexpression of miR-29a was confirmed by TaqMan RT-PCR and significantly suppressed the growth of the hepatocellular carcinoma cell lines MHCC-97L and PLC. Dual-luciferase reporter assays indicated that the SPARC mRNA 3'UTR was directly targeted by miR-29a since the mutated 3'UTR was not affected. Silencing SPARC expression by RNAi knockdown resulted in a similar effect as miR-29a overexpression on hepatocellular carcinoma (HCC) cell growth regulation. Anti-miR-29a oligonucleotides (AMOs) upregulated the levels of SPARC in the HCC cells. The phosphorylation of AKT/mTOR downstream of SPARC was inhibited in miR-29a-overexpressing HCC cells. We further examined and compared the expression levels of miR-29a in HCC tissues and the corresponding nearby non-cancerous liver tissues of 110 patients with HCC by qRT-PCR, and significantly lower expression of miR-29a was observed in the tissues affected by HCC. Our findings demonstrate that the expression of miR-29a is important in the regulation of the SPARC-AKT pathway and HCC growth.

Secreted protein acidic and rich in cysteine (SPARC) suppresses angiogenesis by down-regulating the expression of VEGF and MMP-7 in gastric cancer

Background

Secreted protein acidic and rich in cysteine (SPARC) is a glycoprotein that functions to inhibit angiogenesis, proliferation, and invasion in different types of cancer. The ability of SPARC to modulate neovascularisation is believed to be mediated in part by its ability to modulate the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs). In this study, we aimed to determine the effect of SPARC expression in gastric cancer cells on proliferation and angiogenesis in vitro and in vivo.

Method

We evaluated expression of SPARC in seven human gastric cancer cell lines. Then we established a stably transfected SPARC overexpressed cell line (BGC-SP) and a stably transfected SPARC knock-down cell line (HGC-sh). The effect of SPARC overexpression and SPARC silencing was studied by examining capillary formation of HUVECs in vitro and a dorsal skin-fold chamber model in vivo. Quantitative real-time PCR and western blotting were performed to detect if the expressions of VEGF and MMP-7 were modulated by SPARC expression. To further determine the effect of SPARC expression on angiogenesis in vivo, xenograft models were established and microvessel density (MVD) of different clones were detected by immunohistochemistry.

Results

Endogenous SPARC overexpression inhibited the expression of VEGF and MMP-7, as well as the angiogenesis induced by BGC-SP cells. Correspondingly, SPARC silencing increased the expression of VEGF and MMP-7, as well as the angiogenesis induced by HGC-sh cells. Elevated angiogenesis induced by SPARC silencing in HGC-sh cells was decreased when VEGF was neutralised by antibodies, and MMP-7 was knocked down in vitro.

Conclusion

SPARC suppresses angiogenesis of gastric cancer by down-regulating the expression of VEGF and MMP-7.

Sparc-like protein 1 is a new marker of human glioma progression

High-grade gliomas (glioblastomas) are the most common and deadly brain tumors in adults, currently with no satisfactory treatment available. Apart from de novo glioblastoma, it is currently accepted that these malignancies mainly progress from lower grade glial tumors. However, the molecular entities governing the progression of gliomas are poorly understood. Extracellular and membrane proteins are key biomolecules found at the cell-to-cell communication interface and hence are a promising proteome subpopulation that could help understand the development of glioma. Accordingly, the current study aims at identifying new protein markers of human glioma progression. For this purpose, we used glial tumors generated orthotopically with T98G and U373 human glioma cells in nude mice. This setup allowed also to discriminate the protein origin, namely, human (tumor) or mouse (host). Extracellular and membrane proteins were selectively purified using biotinylation followed by streptavidin affinity chromatography. Isolated proteins were digested and then identified and quantified employing 2D-nano-HPLC-MS/MS analysis. A total of 23 and 27 up-regulated extracellular and membrane proteins were identified in the T98G and U373 models, respectively. Approximately two-thirds of these were predominantly produced by the tumor, whereas the remaining proteins appeared to be mainly overexpressed by the host tissue. Following extensive validation, we have focused our attention on sparc-like protein 1. This protein was further investigated using immunohistochemistry in a large collection of human glioma samples of different grades. The results showed that sparc-like protein 1 expression correlates with glioma grade, suggesting the possible role for this protein in the progression of this malignancy.

Genes responsible for the characteristics of primary cultured invasive phenotype hepatocellular carcinoma cells

The common genes responsible for the characteristics of primary cultured invasive phenotype hepatocellular carcinoma (HCC) cells were investigated. Primary cultured HCC cells from three patients were separated by Matrigel invasion into parent and invasive cells. Whole human genome oligo microarray was applied to detect the differentially expressed genes in invasive cells. A purchased HCC cell line (HA 22T/VGH) was studied for comparison. Forty genes were consistently up-regulated and 14 genes were consistently down-regulated among primary cultured invasive cells. Among these genes, only three up-regulated genes (CNN1, PLAT, SPARC) and one down-regulated tumor suppressor gene (MDFI) had same expressions in invasive cells originated from purchased cell line. For primary cultured invasive cells, differential expressions of several groups of common genes are known to have capacities to promote proliferation (CAV1, IL6, PLAT, RRAD, SRPX), remodeling of extracellular matrix (COL1A1, COL1A2, NID2, TNC, RELN, SPARC), migration (ACTG2, CAV1, CCL2, CCL26, CDC42EP3, CNN1, PHLDB2, PLAT, RRAD, SRPX), implantation (IL6), immune escape (CD70) and angiogenesis (CCL2, IL6, IL18, PLAT, SLIT3). Two genes related to signal transduction (AXL, RASL10B) and one related to metabolism (PTGS2) also showed consistent expressions. Differential expressions of these genes are capable for tumor invasiveness. In conclusion, the characteristics of invasive phenotype HCC cells are originated from differential expressions of several groups of genes rather than few target genes. This information may give us a new insight to design new stratagems in HCC treatment. Analysis of the results from a purchased cell line may have bias due to long-term repeated in vitro cultures.

Secreted protein acidic and rich in cysteines-like 1 suppresses aggressiveness and predicts better survival in colorectal cancers

PURPOSE

Secreted protein acidic and rich in cysteines-like 1 (SPARCL1) is an extracellular matrix glycoprotein with malignancy-suppressing potential. The hypothesis that SPARCL1 reduces cancer invasiveness and predicts better survival in colorectal cancers (CRC) was investigated.

EXPERIMENTAL DESIGN

Stable SPARCL1 transfectants, RKO-SPARCL1, and corresponding vector control were constructed and implanted into nude mice to generate a mouse xenograft model of liver metastasis. Also, a retrospective outcome study was conducted on the COH set (222 CRCs) and ZJU set (412 CRCs). The protein expression level of SPARCL1 was determined by immunohistochemistry. The Kaplan-Meier and Cox analyses were used for survival analysis. The association of SPARCL1 with mesenchymal-epithelial transition (MET) was examined by reverse transcription PCR (RT-PCR) and Western blot analysis.

RESULTS

The ectopic expression of SPARCL1 significantly reduced the potential for anchorage-independent growth, migration, invasion and induced cell differentiation in RKO and SW620 cells. In mouse xenograft model, the expression of SPARCL1 significantly reduced the liver metastasis (P < 0.01). The patient-based studies revealed that the expression of SPARCL1 was related to better differentiation (P < 0.01), less lymph node involvement [OR, 0.67; 95% confidence interval (CI), 0.45-1.00], and less distant metastasis (OR, 0.38; 95% CI, 0.18-0.79). The Kaplan-Meier and Cox analysis showed that the expression of SPARCL1 was associated with better overall survival (log-rank: P < 0.01; HR, 0.57; 95% CI, 0.39-0.84). Transfection of SPARCL1 induced MET of colon cancer cells.

CONCLUSION

SPARCL1 functions as a tumor suppressor promoting differentiation possibly via MET, which inhibits the aggressiveness of CRCs.

SPARC is a key regulator of proliferation, apoptosis and invasion in human ovarian cancer

Background

Secreted protein acidic and rich in cysteine (SPARC), a calcium-binding matricellular glycoprotein, is implicated in the progression of many cancers. In this study, we investigated the expression and function of SPARC in ovarian cancer.

Methods

cDNA microarray analysis was performed to compare gene expression profiles of the highly invasive and the low invasive subclones derived from the SKOV3 human ovarian cancer cell line. Immunohistochemistry (IHC) staining was performed to investigate SPARC expression in a total of 140 ovarian tissue specimens. In functional assays, effects of SPARC knockdown on the biological behavior of ovarian cancer cells were investigated. The mechanisms of SPARC in ovarian cancer proliferation, apoptosis and invasion were also researched.

Results

SPARC was overexpressed in the highly invasive subclone compared with the low invasive subclone. High SPARC expression was associated with high stage, low differentiation, lymph node metastasis and poor prognosis of ovarian cancer. Knockdown of SPARC expression significantly suppressed ovarian cancer cell proliferation, induced cell apoptosis and inhibited cell invasion and metastasis.

Conclusion

SPARC is overexpressed in highly invasive subclone and ovarian cancer tissues and plays an important role in ovarian cancer growth, apoptosis and metastasis.

Aberrant methylation of SPARC in human hepatocellular carcinoma and its clinical implication

AIM: To investigate the methylation status of secreted protein acidic and rich in cysteine (SPARC) in human hepatocellular carcinoma (HCC) and evaluate its clinical implication.

METHODS: The methylation status of SPARC was analyzed in one HCC cell line (SMMC-7721) and 60 pairs of HCC and corresponding nontumorous tissues by methylation-specific polymerase chain reaction and bisulfite sequencing. The expression of SPARC mRNA and protein were examined by reverse transcription polymerase chain reaction and immunohistochemistry, respectively. The correlations between the methylation status and the gene expression, the clinicopathological parameters, as well as the prognosis after surgery were analyzed.

RESULTS: In the SMMC-7721 cell line, the loss of SPARC expression was correlated with the aberrant methylation and could be reactivated by the demethylating agent 5-aza-2’-deoxycytidine. Methylation frequency of SPARC in HCC was significantly higher than that in the corresponding nontumorous tissues (45/60 vs 7/60, P < 0.001), and it was correlated with the pathological classification (P = 0.019). The downregulation of the SPARC mRNA expression in HCC was correlated with the SPARC methylation (P = 0.040). The patients with methylated SPARC had a poorer overall survival than those without methylated SPARC (28.0 mo vs 41.0 mo, P = 0.043).

CONCLUSION: Aberrant methylation is an important mechanism for SPARC inactivation in HCC and SPARC methylation may be a promising biomarker for the diagnosis and prognosis of HCC.

Proteolysis of the matricellular protein hevin by matrix metalloproteinase-3 produces a SPARC-like fragment (SLF) associated with neovasculature in a murine glioma model

The matricellular SPARC-family member hevin (Sparc-like 1/SPARCL-1/SC1/Mast9) contributes to neural development and alters tumor progression in a range of mammalian models. Based on sequence similarity, we hypothesized that proteolytic digestion of hevin would result in SPARC-like fragments (SLF) that affect the activity and/or location of these proteins. Incubation of hevin with matrix metalloproteinase-3 (MMP-3), a protease known to cleave SPARC, produced a limited number of peptides. Sequencing revealed the major proteolytic products to be SPARC-like in primary structure. In gliomas implanted into murine brain, a SLF was associated with SPARC in the neovasculature but not with hevin, the latter prominent in the astrocytes encompassed by infiltrating tumor. In this model of invasive glioma that involves MMP-3 activity, host-derived SLF was not observed in the extracellular matrix adjacent to tumor cells. In contrast, it occurred with its homolog SPARC in the angiogenic response to the tumor. We conclude that MMP-3-derived SLF is a marker of neovessels in glioma, where it could influence the activity of SPARC.

Matricellular proteins: a sticky affair with cancers

The multistep process of metastasis is a major hallmark of cancer progression involving the cointeraction and coevolution of the tumor and its microenvironment. In the tumor microenvironment, tumor cells and the surrounding stromal cells aberrantly secrete matricellular proteins, which are a family of nonstructural proteins in the extracellular matrix (ECM) that exert regulatory roles via a variety of molecular mechanisms. Matricellular proteins provide signals that support tumorigenic activities characteristic of the metastastic cascade such as epithelial-to-mesenchymal (EMT) transition, angiogenesis, tumor cell motility, proliferation, invasion, evasion from immune surveillance, and survival of anoikis. Herein, we review the current understanding of the following matricellular proteins and highlight their pivotal and multifacted roles in metastatic progression: angiopoietin-like protein 4 (ANGPTL4), CCN family members cysteine-rich angiogenic inducer 61 (Cyr61/CCN1) and CCN6, osteopontin (OPN), secreted protein acidic and rich in cysteine (SPARC), tenascin C (TNC), and thrombospondin-1 and -2 (TSP1, TSP2). Insights into the signaling mechanisms resulting from the interaction of these matricellular proteins and their respective molecular partner(s), as well as their subsequent contribution to tumor metastasis, are discussed. In addition, emerging evidences of their promising potential as therapeutic options and/or targets in the treatment of cancer are also highlighted.

Down-regulated SPARCL1 is associated with clinical significance in human gastric cancer

BACKGROUND

SPARC-like protein 1 (SPARCL1), a member of extracelluar matrix glycoprotein, is involved in many physiological functions.

METHODS

Tissue microarray (TMA) blocks were constructed based on 1,072 Chinese patients, containing both gastric cancer (GC) tissues and adjacent normal mucosa tissues. We analyzed the expression of SPARCL1 from both mRNA and protein level, using Real-time quantitative polymerase chain reaction (qRT-PCR), semi-quantitative PCR, immunohistochemistry (IHC), and Western blotting. Loss of heterozygosity analysis at the SPARCL1 gene locus was carried out using ten paired tumor and matched normal tissues.

RESULTS

SPARCL1 mRNA was significantly reduced in tumor specimens compared with normal tissues. Down-regulation of SPARCL1 protein was detected in 413 cases (38.7%) of 1,072 primary gastric tumor tissues. Kaplan-Meier survival curves demonstrated that SPARCL1-positive patients had better median survival time than SPARCL1-negative patients (59 months vs. 28 months, P = 0.001). Multivariate survival analysis revealed that SPARCL1 was an independent prognostic factor in gastric adenocarcinoma patients with no metastasis and well/moderately differentiated. The incidence of LOH for each individual marker was 12.5% (1/8) for D4S2462, 20% (2/10) for D4S2929, and 33.3% (3/9) for SPARCL1.

CONCLUSIONS

Our study revealed the clinical significance of SPARCL1 expression, providing a basis that the loss of SPARCL1 is a negative event in GC progression and prognosis. Furthermore, SPARCL1 protein might be considered to be a potential differentiation marker.

Control of gene expression by the retinoic acid-related orphan receptor alpha in HepG2 human hepatoma cells

Retinoic acid-related Orphan Receptor alpha (RORα; NR1F1) is a widely distributed nuclear receptor involved in several (patho)physiological functions including lipid metabolism, inflammation, angiogenesis, and circadian rhythm. To better understand the role of this nuclear receptor in liver, we aimed at displaying genes controlled by RORα in liver cells by generating HepG2 human hepatoma cells stably over-expressing RORα. Genes whose expression was altered in these cells versus control cells were displayed using micro-arrays followed by qRT-PCR analysis. Expression of these genes was also altered in cells in which RORα was transiently over-expressed after adenoviral infection. A number of the genes found were involved in known pathways controlled by RORα, for instance LPA, NR1D2 and ADIPOQ in lipid metabolism, ADIPOQ and PLG in inflammation, PLG in fibrinolysis and NR1D2 and NR1D1 in circadian rhythm. This study also revealed that genes such as G6PC, involved in glucose homeostasis, and AGRP, involved in the control of body weight, are also controlled by RORα. Lastly, SPARC, involved in cell growth and adhesion, and associated with liver carcinogenesis, was up-regulated by RORα. SPARC was found to be a new putative RORα target gene since it possesses, in its promoter, a functional RORE as evidenced by EMSAs and transfection experiments. Most of the other genes that we found regulated by RORα also contained putative ROREs in their regulatory regions. Chromatin immunoprecipitation (ChIP) confirmed that the ROREs present in the SPARC, PLG, G6PC, NR1D2 and AGRP genes were occupied by RORα in HepG2 cells. Therefore these genes must now be considered as direct RORα targets. Our results open new routes on the roles of RORα in glucose metabolism and carcinogenesis within cells of hepatic origin.

SPARCL1, Shp2, MSH2, E-cadherin, p53, ADCY-2 and MAPK are prognosis-related in colorectal cancer

AIM: To investigate the expression of markers that are correlated with the prognosis of colorectal cancer (CRC) patients.

METHODS: One hundred and fifty-six CRC patients were followed up for more than 3 years after radical surgery. Immunohistochemical (IHC) analysis was performed to detect the expression of 14 pathway-related markers (p53, APC, p21ras, E-cadherin, endothelin-B receptor, Shp2, ADCY-2, SPARCL1, neuroligin1, hsp27, mmp-9, MAPK, MSH2 and rho) in specimens from these patients. Bioinformatics analysis involving a Support Vector Machine (SVM) was used to determine the best prognostic model from combinations of these markers.

RESULTS: Seven markers (SPARCL1, Shp2, MSH2, E-cadherin, p53, ADCY-2 and MAPK) were significantly related to the prognosis and clinical pathological features of the CRC patients (P < 0.05). Prognostic models were established through SVM from combinations of these 7 markers and proved able to differentiate patients with dissimilar survival, especially in stage II/III patients. According to the best prognostic model, the p53/SPARCL1 model, patients having high p53 and low SPARCL1 expression had about 50% lower 3-year survival than others (P < 0.001).

CONCLUSION: SPARCL1, Shp2, MSH2, E-cadherin, p53, ADCY-2 and MAPK are potential prognostic markers in CRC. A p53/SPARCL1 bioinformatics model may be used as a supplement to tumor-nodes-metastasis staging.

Anti-cancer role of SPARC, an inhibitor of adipogenesis

SPARC (a secreted protein acidic and rich in cysteine) has a reputation for being potent anti-cancer and anti-obesity molecule. It is one of the first known matricellular protein that modulates interactions between cells and extracellular matrix (ECM) and is associated with the 'balance' of white adipose tissue (WAT) as well as lipogenesis and lipolysis during adipogenesis. Adipogenesis is an indication for the development of obesity and has been related to a wide variety of cancers including breast cancer, endometrial cancer, esophageal cancer, etc. Adipogenesis mainly involves ECM remodeling, changes in cell-ECM interactions, and cytoskeletal rearrangement. SPARC can also prevent hypertrophy of adipocytes and hyperplasia of adipocyte progenitors. In addition to SPARC's inhibitory role in adipogenesis, it has also been known to be involved in cell cycle, cell proliferation, cell invasion, adhesion, migration, angiogenesis and apoptosis. Molecular cancer biology and clinical biochemistry have significantly enhanced our understanding of the mechanisms that motivate the anti-cancer and anti-obesity action of SPARC. Recent studies elucidating the signaling pathways that are activated by SPARC can help develop the beneficial aspects of SPARC for cancer therapy and obesity prevention. This review focuses on the anti-cancer role of SPARC as it pertains to obesity.

Increased invasiveness and aggressiveness in breast epithelia with cytoplasmic p63 expression

Our previous studies revealed that pregnancy associated breast cancer (PABC) had significantly reduced nuclear p63 expression in myoepithelia, while intense cytoplasmic p63 expression in associated epithelia. Our current study assessed these epithelia using immunohistochemistry with a panel of aggressiveness and invasiveness related markers and comparative genomic hybridization (array-CGH) with over 30,000 DNA probes. These epithelia showed several unique alterations, including (1) immunohistochemical and morphological resemblance to invasive cancer, (2) significant gain in copy numbers of DNA coding genes for morphogenesis, angiogenesis, and metastasis, and (3) significant loss in copy numbers of DNA coding genes for tumor suppressors, cell adhesion, and macromolecular complex assembly or intra-cellular trafficking. Detected array-CGH alterations correlated well with in vivo expression of a number of corresponding proteins tested. These findings suggest that aberrant sub-cellular localization of p63 expression in normal or hyperplastic appearing epithelial cells may significant contribute to increased invasiveness and aggressiveness of these cells.