Frequent inactivation of SPARC by promoter hypermethylation in colon cancers

Glucose oxidase virus-based nanoreactors for smart breast cancer therapy

BACKGROUND

Breast cancer is the most common malignant tumor disease and the leading cause of female mortality. The evolution of nanomaterials science opens the opportunity to improve traditional cancer therapies, enhancing therapy efficiency and reducing side effects.

METHODS AND MAJOR RESULTS

Herein, protein cages conceived as enzymatic nanoreactors were designed and produced by using virus-like nanoparticles (VLPs) from Brome mosaic virus (BMV) and containing the catalytic activity of glucose oxidase (GOx) enzyme. The GOx enzyme was encapsulated into the BMV capsid (VLP-GOx), and the resulting enzymatic nanoreactors were coated with human serum albumin (VLP-GOx@HSA) for breast tumor cell targeting. The effect of the synthesized GOx nanoreactors on breast tumor cell lines was studied in vitro. Both nanoreactor preparations VLP-GOx and VLP-GOx@HSA showed to be highly cytotoxic for breast tumor cell cultures. Cytotoxicity for human embryonic kidney cells was also found. The monitoring of nanoreactor treatment on triple-negative breast cancer cells showed an evident production of oxygen by the catalase antioxidant enzyme induced by the high production of hydrogen peroxide from GOx activity.

CONCLUSIONS AND IMPLICATIONS

The nanoreactors containing GOx activity are entirely suitable for cytotoxicity generation in tumor cells. The HSA functionalization of the VLP-GOx nanoreactors, a strategy designed for selective cancer targeting, showed no improvement in the cytotoxic effect. The GOx containing enzymatic nanoreactors seems to be an interesting alternative to improve the current cancer therapy. In vivo studies are ongoing to reinforce the effectiveness of this treatment strategy.

Prognostic value of SPARC in hepatocellular carcinoma: A systematic review and meta-analysis

Objective

Hepatocellular carcinoma (HCC) is characterized by a high degree of malignancy, rapid proliferation of tumor cells, and early liver metastasis. Resistance to multiple drugs independent of the high expression of secreted protein acidic and rich in cysteine (SPARC) is associated with a high risk of recurrence and mortality. However, the prognostic value of SPARC in patients with HCC remains unclear. Therefore, we performed a meta-analysis to evaluate the relationship between the expression of SPARC and the prognosis of patients with HCC.

Methods

We searched for relevant articles in the CNKI, PubMed, EMBASE, and Web of Science databases. The 95% confidence intervals (CIs) were calculated for combined overall survival (OS) and disease-free survival (DFS) to assess the prognostic value of expression of SPARC in patients with HCC.

Results

In six of the studies, SPARC expression status was significantly associated with OS (combined hazard ratio [HR], 1.38; 95% CI, 1.0–1.82; Z = 2.27, P = 0.02) but not with DFS (combined HR, 0.79; 95% CI, 0.16–4.00, Z = 0.28, P = 0.78). Therefore, it cannot be assumed that upregulated SPARC expression has an effect on DFS in patients with HCC.

Conclusion

Elevated SPARC expression is associated with a low survival rate but not with DFS in patients with HCC. Further studies are needed to confirm our conclusions.

Registration

INPLASY registration number: INPLASY202180115. https://inplasy.com/inplasy-2021-8-0115/.

Effects of SPARC and Possible Receptors on Colon Cancer Cell Line

Objective: The aim of this study was to observe the apoptotic/cytotoxic effects of exogenous SPARC on colon cancer cell line HT-29, then to investigate the function of stabilin-1 and integrin αvβ3, which are possible receptors for SPARC in colon cancer cells and to determine the quantitation of their receptor numbers. Methods: Appropriate doses of exogenous SPARC and it’s inhibitor, cilengitide added to HT-29 cell line were determined by xCELLigence Real-Time Cell Analysis system, SPARC-mediated caspase 3 expressions were measured. Using the RT-PCR system, gene expression levels of SPARC, stabilin-1 and integrin αvβ3 receptors (silenced/nonsilenced with cilengitide) were detected then the numbers of receptors per cell were quantitated by flow cytometry. Results: IC50 value of SPARC was determined as 4.57 μg/mL and IC50 value of cilengitide was determined as 50 nM. 5 μg/mL exogenous SPARC caused increased apoptosis in the HT-29 line. Significant increase in gene expression of integrin αvβ3 receptor was observed in the group incubated with 5 μg/mL SPARC, contrarily, the addition of cilengitide decreased gene expressions. The integrin αvβ3 receptor numbers increased approximately 2-fold with SPARC compared to the control. No significant changes were observed in the gene expression and receptor numbers of stabilin-1. Conclusion: Exogenous SPARC was shown to reduce proliferation and induce apoptosis in colon cancer cells. Integrin αvβ3 is thought to be the possible receptor mediating SPARC in colon cancer cells. Quantification of surface receptors per cell, which we think we have done first, can be considered as a marker in the follow-up of anticancer treatments.

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.

The potential feasibility of nab-paclitaxel as the first-line chemotherapy for ovarian cancer: clinical development and future perspectives

PURPOSE

Optimal first-line chemotherapy regimens are crucial for epithelial ovarian cancer (EOC) treatment. Nab-paclitaxel has showed its considerable survival and low toxicity profiles in first-line treatment for three solid tumors and is recommended as a treatment for recurrent EOC. We focus on clinical efficacy and safety outcomes of nab-paclitaxel in current clinical studies of EOC treatment and aim to explore the potential feasibility of nab-paclitaxel as the first-line treatment for EOC.

METHODS

We searched for eligible studies up to January 2020 in Pubmed. Outcomes of interests included drug regimes, objective response rate (ORR), median progression free survival (PFS), median overall survival (OS) and main adverse events to determine feasibility of nab-paclitaxel.

RESULTS

This review included nine eligible studies. One study about nab-paclitaxel with carboplatin as first-line therapy in ten cases after hypersensitivity to paclitaxel had an ORR of 100%, median PFS of 16.7 months and median OS of 65.4 months. Evidence of nab-paclitaxel activity in platinum-sensitive EOC demonstrated an ORR of 64%, a median time to response of 1.3 months and PFS of 8.5 months. The ORR, median PFS and median OS range in patients with recurrent platinum-resistant EOC from 23%-72%, 4.0-8.5 months, 16.8-17.4 months, respectively. All studies demonstrated manageable toxicity profile in EOC patients.

CONCLUSION

Nab-paclitaxel presents potentials as the first-line chemotherapy for considerable survival and safety in EOC compared to conventional paclitaxel. However, there is no prospective trial in EOC so far. Therefore, more studies about nab-paclitaxel are needed.

SPARC Overexpression Promotes Liver Cancer Cell Proliferation and Tumor Growth

Background: Secreted protein acidic and rich in cysteine (SPARC) plays an important role in cancer development. The roles of SPARC in the liver hepatocellular carcinoma (LIHC) are unclear. Methods: GEPIA2 and UALCAN were used to analyze the SPARC mRNA expression levels in LIHC based on the TCGA database. The GEO database was used to verify the analysis results. Immunohistochemical (IHC) analysis was used to investigate the SPARC protein levels in LIHC tissues. The Kaplan-Meier (KM) plotter was used to analyze the correlation between SPARC and prognosis. The serum SPARC levels were measured by ELISA. CCK8 and murine xenograft models were used to investigate the effect of SPARC on the liver cancer growth in vitro and in vivo. SPARC-correlated genes were screened by LinkedOmics. Results: Based on the TCGA and GEO databases, the analysis showed that the SPARC mRNA expression levels were increased in tumor tissues and peripheral blood mononuclear cell (PBMC) from LIHC compared to normal controls. The IHC analysis showed an increased level of SPARC in LIHC tissues compared to adjacent non-tumor tissues. However, we found that the serum SPARC levels were lower in LIHC than those in healthy controls. The KM plotter showed that there was no significant correlation between the SPARC mRNA levels and overall survival. However, in sorafenib-treated LIHC patients, the high SPARC expression predicts favorable prognosis. Furthermore, the endogenous SPARC overexpression promotes liver cancer cell proliferation in vitro and tumor growth in vivo, while there was no significant effect of exogenous SPARC treatment on liver cancer cell proliferation. Function enrichment analysis of SPARC-correlated genes indicated a critical role of interaction with an extracellular matrix in SPARC-promoting cancer cell proliferation. Conclusion: SPARC mRNAs were increased in LIHC tumor tissues, and SPARC overexpression may promote the liver cancer growth. Further studies are needed to clarify the potential prognostic value of SPARC, both in tissues and in circulation.

Discoidin domain receptor 2 activation of p38 mitogen-activated protein kinase as an important pathway for osteonectin-regulating osteoblast mineralization

Objective

The present study aimed to determine the role of the discoidin domain receptor 2 (DDR2) in the osteonectin (ON) regulation of osteoblast mineralization through the activation of p38 mitogen-activated protein kinase (MAPK).

Methods

Four groups were established: the ON group, the inhibitor group, the Ddr2-small interfering ribonucleic acid (siRNA) group, and the control group. Osteoblasts from the parietal bones of neonatal Sprague–Dawley rats were isolated and cultured. In the ON group, 1 µg/mL ON was added to the osteoblasts. The gene expressions of collagen 1 (Col 1) and Ddr2 were detected using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In the inhibitor group, the osteoblasts were added to WRG-28 (a specific DDR2 inhibitor), and in the Ddr2-siRNA group, the osteoblasts were transfected with Ddr2-siRNA. The gene and protein expressions of DDR2, bone sialoprotein, osteocalcin, osteopontin, and p38 MAPK were determined using RT-qPCR and western blot analysis. Alizarin red staining and transmission electron microscopy were used to detect mineralization.

Results

The results showed that ON enhanced the osteoblast Col 1 and Ddr2 gene expressions, while the use of a Ddr2-siRNA/DDR2-blocker decreased the OPN, BSP, OCN, and P38 gene and protein expressions and reduced osteoblast cellular activity and mineralized nodules.

Conclusion

The present study demonstrated that DDR2 activation of p38 MAPK is an important approach to ON-regulating osteoblast mineralization.

Label-free quantitation of the changes in salivary proteome associated with the chronic consumption of the betel nut (Areca catechu)

Areca nut or betel nut chewing is most frequently used in Pakistan and is associated with a high risk for oral cancer. Until now, however, there has not been any research conducted on the long-term effect(s) of betel nut chewing on the saliva proteome. In the present study, initially, the changes in the saliva proteome associated with betel nut chewing were investigated. Secondly, the analysis was focused on the changes in salivary proteome with respect to prolonged usage of betel nuts. After extraction, the saliva proteins were digested into peptides and these were subsequently analyzed using mass spectrometry. Data are available via ProteomeXchange with identifier PXD029768. Label-free quantitation of saliva samples revealed a total of 12 proteins that were differentially expressed between betel nut addicts (BNAs), and the control group. The study groups were further divided into three subgroups, the BNA-1, BNA-2, and BNA-3 groups, with respect to the extent of consumption of betel nuts in terms of years. The data analysis revealed a more detailed profiling of proteins expressed after five, ten, and more than ten years of betel nut consumption. A total of 30, 17, and 22 proteins were found to be differentially expressed when divided into the BNA-1, BNA-2, and BNA-3 groups. The present study shows that the chronic usage of betel nuts leads to the expression of proteins, such as SPARC1, profilin, and SBSN, which are known to be involved in head and neck cancers.

ECM Remodeling in Squamous Cell Carcinoma of the Aerodigestive Tract: Pathways for Cancer Dissemination and Emerging Biomarkers

Squamous cell carcinomas (SCC) include a number of different types of tumors developing in the skin, in hollow organs, as well as the upper aerodigestive tract (UADT) including the head and neck region and the esophagus which will be dealt with in this review. These tumors are often refractory to current therapeutic approaches with poor patient outcome. The most important prognostic determinant of SCC tumors is the presence of distant metastasis, significantly correlating with low patient survival rates. Rapidly emerging evidence indicate that the extracellular matrix (ECM) composition and remodeling profoundly affect SSC metastatic dissemination. In this review, we will summarize the current knowledge on the role of ECM and its remodeling enzymes in affecting the growth and dissemination of UADT SCC. Taken together, these published evidence suggest that a thorough analysis of the ECM composition in the UADT SCC microenvironment may help disclosing the mechanism of resistance to the treatments and help defining possible targets for clinical intervention.

ECM Remodeling in Squamous Cell Carcinoma of the Aerodigestive Tract: Pathways for Cancer Dissemination and Emerging Biomarkers

Simple Summary

Local and distant metastasis of patients affected by squamous cell carcinoma of the upper aerodigestive tract predicts poor prognosis. In the latest years, the introduction of new therapeutic approaches, including targeted and immune therapies, has improved the overall survival. However, a large number of these patients do not benefit from these treatments. Thus, the identification of suitable prognostic and predictive biomarkers, as well as the discovery of new therapeutic targets have emerged as a crucial clinical need. In this context, the extracellular matrix represents a suitable target for the development of such therapeutic tools. In fact, the extracellular matrix is composed by complex molecules able to interact with a plethora of receptors and growth factors, thus modulating the dynamic crosstalk between cancer cells and the tumor microenvironment. In this review, we summarize the current knowledge of the role of the extracellular matrix in affecting squamous cell carcinoma growth and dissemination. Despite extracellular matrix is known to affect the development of many cancer types, only a restricted number of these molecules have been recognized to impact on squamous cell carcinoma progression. Thus, we consider that a thorough analysis of these molecules may be key to develop new potential therapeutic targets/biomarkers.

Abstract

Squamous cell carcinomas (SCC) include a number of different types of tumors developing in the skin, in hollow organs, as well as the upper aerodigestive tract (UADT) including the head and neck region and the esophagus which will be dealt with in this review. These tumors are often refractory to current therapeutic approaches with poor patient outcome. The most important prognostic determinant of SCC tumors is the presence of distant metastasis, significantly correlating with low patient survival rates. Rapidly emerging evidence indicate that the extracellular matrix (ECM) composition and remodeling profoundly affect SSC metastatic dissemination. In this review, we will summarize the current knowledge on the role of ECM and its remodeling enzymes in affecting the growth and dissemination of UADT SCC. Taken together, these published evidence suggest that a thorough analysis of the ECM composition in the UADT SCC microenvironment may help disclosing the mechanism of resistance to the treatments and help defining possible targets for clinical intervention.

Mesenchymal stem cells induce tumor stroma formation and epithelial‑mesenchymal transition through SPARC expression in colorectal cancer

Tumor-stroma interactions serve a crucial role in the development of colorectal cancer (CRC), in which secreted protein acidic and rich in cysteine (SPARC) has been implicated. Due to interactions between cancer and stromal cells [mesenchymal stem cells (MSCs)], SPARC gene expression is markedly upregulated in CRC cells. The present study investigated the role of SPARC in CRC development and its potential as a biomarker. Specifically, the present study examined the association between SPARC expression and clinicopathological characteristics in 42 cases of CRC. SPARC expression in cancer cells was associated with T grade, N grade (TNM classification), stage and poor prognosis. Furthermore, the area of fibroblast-activating protein-positive staining around the cancer cells was increased in SPARC-positive compared with SPARC-negative cases. Proliferation and wound healing assays in SPARC-silenced KM12SM cells [short hairpin RNA SPARC (shSPARC)], the reduced SPARC expression of which was demonstrated by reverse transcription-quantitative PCR, revealed that the proliferative and migratory capacity of shSPARC cells did not differ from that of wild-type (WT) cells. However, it was markedly reduced when co-cultured with MSCs. Furthermore, in vivo, immunohistological analysis and RNA sequencing were conducted in an orthotopic implanted mouse model. Tumor growth and lymph node metastasis were markedly suppressed in shSPARC-transplanted tumors compared with WT-transplanted tumors, with a more marked suppression observed following shSPARC co-transplantation with MSCs. Immunohistological examination further revealed that the stromal reaction and epithelial-mesenchymal transition (EMT) were markedly suppressed in tumors co-transplanted with shSPARC and MSCs, and these results were consistent with RNA sequencing using RNA extracted from orthotopic tumors. Overall, these results suggested that SPARC expression in CRC cells is dependent on the interaction between cancer cells and stromal cells to induce EMT and promote stromal formation in the tumor microenvironment, suggesting its suitability as a novel target molecule for CRC treatment.

Peptide-functionalized metal-organic framework nanocomposite for ultrasensitive detection of secreted protein acidic and rich in cysteine with practical application

In this work, we have prepared peptide-functionalized metal-organic frameworks (MOFs) as signal-amplifying tags for the detection of secreted protein acidic and rich in cysteine (SPARC). Furthermore, enzyme-MOF nanocomposites are fabricated via a coprecipitation strategy between horse radish peroxidase (HRP) and ZIF-90, where ZIF-90 is used as a protective support for HRP immobilization. Meanwhile, the peptide sequence has been designed as SPARC-binding peptide, which imparts biorecognition functionality to HRP@ZIF-90 for performing a colorimetric sensor. Therefore, during the test, HRP molecules can be quickly released from nanocomposites by acidic condition to catalyze chromogenic reaction, enabling the ultrasensitive detection of SPARC with a low detection limit of 30 fg/mL. Moreover, the content of SPARC in colon cancer tissues with different degrees of differentiation can be determined with this sensor, demonstrating that the expression of SPARC is closely related to the occurrence, invasion and metastasis of human colon cancer. These results may show the potential applications of this biosensor in SPARC fundamental research as well as clinical diagnosis in the future.

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.

Potential Prognostic Role of SPARC Methylation in Non-Small-Cell Lung Cancer

The silencing of SPARC (secreted protein acid and rich in cysteine) gene through methylation of its promoter region represents a common event in many solid tumors and it is frequently associated with tumor progression and an aggressive clinical outcome. Anyhow, the data concerning the epigenetic mechanism of SPARC deregulation and its prognostic value in lung cancer are still incomplete. We explored the aberrant methylation of SPARC and its effects in 4 non-small cell lung cancer (NSCLC) cell lines and 59 NSCLC tissues and correlated the methylation levels with clinical-pathological features and disease outcome of patients. In 3 out of 4 tumor cell lines high SPARC methylation levels were observed. An inverse correlation between the epigenetic silencing and SPARC expression was confirmed by 5-Aza-2′-deoxycytidine ((5-Aza-CdR) treatment that also significantly induced a reduction in cell viability, proliferation and tumor cell migration. In tissues, the DNA methylation levels of the SPARC gene were significantly lower in paired non-neoplastic lungs (NLs) and normal lungs distant from tumor (NLDTs) than in NSCLCs (p = 0.002 and p = 0.0034 respectively). A promoter hypermethylation was detected in 68% of squamous cell carcinoma (SqCCs, 17/25) and 56% of adenocarcinoma (ADCs, 19/34), with SqCC showing the highest levels of methylation. Higher SPARC methylation levels were significantly associated with higher mortality risk both in all NSCLCs early stage patients (Hazard Ratio, HR = 1.97; 95% Confidence Interval, CI: 1.32–2.93; p = 0.001) and in those with SqCC (HR = 2.96; 95% CI: 1.43–6.12; p = 0.003). Promoter methylation of SPARC gene should represent an interesting prognostic biomarker in NSCLC, with potential application in the squamous early-stage context. Further research in this setting on larger independent cohorts of lung patients with different histologies and stages of disease are warranted.

Secreted protein acidic and rich in cysteine (SPARC) regulates thermogenesis in white and brown adipocytes

SPARC, also known as osteonectin, is well known for its physiological roles in bone formation and tissue remodeling, as well as in cancer pathology; however, evidence regarding its function in adipocytes is lacking. The present study explored the physiological role of SPARC in cultured 3T3-L1 white and HIB1B brown adipocytes of murine cell lines. Treatment of recombinant SPARC upregulated the fat browning marker proteins and genes in white adipocytes and activated brown adipocytes. Conversely, knockdown of Sparc markedly reduced these genes and proteins in both cell lines. In addition, recombinant SPARC inhibited expression of adipogenic and lipogenic proteins but elevated lipolytic and fatty acid oxidation proteins. Furthermore, in silico analysis revealed that SPARC directly interacted and regulated VEGF in adipocytes. In conclusion, SPARC acts as a regulatory protein in both white and brown adipocytes by controlling thermogenesis and is thus regarded as a possible therapeutic target for treatment of obesity.

Downregulation of SPARC Expression Decreases Cell Migration and Invasion Involving Epithelial-Mesenchymal Transition through the p-FAK/p-ERK Pathway in Esophageal Squamous Cell Carcinoma

Purpose: Secreted protein acidic and rich in cysteine (SPARC) is an extracellular glycoprotein overexpressed in various malignancies, including esophageal squamous cell carcinoma (ESCC), and is involved in tumor development and progression. This study was initially designed to investigate the biological roles of SPARC in ESCC cell lines by silencing SPARC expression. Methods: The expression of SPARC was examined in eight human ESCC cell lines. Eca109 and HKESC cell lines with high SPARC expression were selected and transiently transfected with SPARC-targeted small interfering RNAs (siRNAs) and subsequently evaluated its impact on cell proliferation, migration and invasion in vitro, as well as the underlying mechanism. Results: Knockdown of SPARC by the specified siRNAs in Eca109 and HKESC cell lines resulted in dramatically downregulation of SPARC expression, and significantly decreased cell migration and invasion involving epithelial-mesenchymal transition (EMT) in vitro. Moreover, SPARC-targeted siRNA reduced the activation of phosphorylated focal adhesion kinase (p-FAK) and extracellular regulated protein kinase (p-ERK). Furthermore, downregulation of either FAK or SPARC expression with specified siRNAs inhibited the phosphorylation of ERK and inhibited cell migration and invasion. However, decreased SPARC expression showed no impact on cell proliferation, survival or apoptosis of Eca109 and HKESC cells when comparing to control transfected groups. Conclusions: These results demonstrated that downregulation of SPARC could decrease cell migration and invasion involving EMT via the p-FAK/p-ERK pathway that might serve as a novel therapeutic target against ESCC.

Aberrant methylation of secreted protein acidic and rich in cysteine gene and its significance in gastric cancer

BACKGROUND

Aberrant methylation in DNA regulatory regions could downregulate tumor suppressor genes without changing the sequences. However, our knowledge of secreted protein acidic and rich in cysteine (SPARC) and its aberrant methylation in gastric cancer (GC) is still inadequate. In the present research, we performed fundamental research to clarify the precise function of methylation on SPARC and its significance in GC.

AIM

To investigate promoter methylation and the effects of the SPARC gene in GC cells and tissues and to evaluate its clinical significance.

METHODS

Plasmids that overexpressed the SPARC gene were transfected into human GC BGC-823 cells; non-transfected cells were used as a control group (NC group). Quantitative real-time polymerase chain reaction and western blotting (WB) were then used to detect the expression of SPARC. Methylation-specific polymerase chain reaction was executed to analyze the gene promoter methylation status. Cell viability was measured by the cell counting kit-8 assay. The migration and invasion ability of cells were detected by scratch assays and transwell chamber assays, respectively. Cell cycle events and apoptosis were observed with a flow cytometer.

RESULTS

The expression of SPARC mRNA in GC tissues and cells was significantly lower and showed differing degrees of hypermethylation, respectively, than that in normal adjacent tissues and control cells. Treatment with 5-Aza-2’-deoxycytidine (5-Aza-Cdr) was able to restore the expression of SPARC and reverse promoter hypermethylation. Overexpression of the SPARC gene significantly inhibited proliferation, migration, and invasion of GC cells, while also causing cell cycle arrest and apoptosis; the NC group exhibited the opposite effects.

CONCLUSION

This study demonstrated that SPARC could function as a tumor suppressor and might be silenced by promoter hypermethylation. Furthermore, in GC cells, SPARC inhibited migration, invasion, and proliferation, caused cell cycle arrest at the G₀/G₁ phase, and promoted apoptosis.

Impact of Fibroblast-Derived SPARC on Invasiveness of Colorectal Cancer Cells

Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein modulating cell-matrix interactions and was found up-regulated in tumor stroma. To explore the effect of high stromal SPARC on colorectal cancer (CRC) cell behavior and clinical outcome, this study determined SPARC expression in patients suffering from stage II and III CRC using a publicly available mRNA data set and immunohistochemistry of tissue microarray sections. Moreover, in vitro co-culture models using CRC cell lines together with colon-associated fibroblasts were established to determine the effect of fibroblast-derived SPARC on cancer cells. In 466 patient samples, high SPARC mRNA was associated with a shorter disease-free survival. In 99 patients of the tissue microarray cohort, high stromal SPARC in the primary tumor was an independent predictor of shorter survival in patients with relapse (27 cases; HR = 4574, p = 0.004). In CRC cell lines, SPARC suppressed phosphorylation of focal adhesion kinase and stimulated cell migration. Colon-associated fibroblasts increased migration velocity by 30% and doubled track-length in SPARC-dependent manner. In a 3D co-culture system, fibroblast-derived SPARC enhanced tumor cell invasion. Taken together, stromal SPARC had a pro-metastatic impact in vitro and was a characteristic of aggressive tumors with poor prognosis in CRC patients.

Altered CSF Proteomic Profiling of Paediatric Acute Lymphocytic Leukemia Patients with CNS Infiltration

Background

For childhood acute lymphocytic leukemia (ALL), central nervous system leukemia (CNSL) is still the main reason of treatment failure. Changes of cerebrospinal fluid (CSF) proteome are deemed to occur after intrathecal chemotherapy.

Objective

To find critical CSF biomarkers, which could be utilized to increase diagnostic and prognostic accuracy of CNSL.

Methods

We performed proteomic profiling of CSF before and after the treatment of six sporadic paediatric patients diagnosed as ALL with central nervous system (CNS) involvement. CSF samples were properly processed and analyzed through the use of label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Results

Among identified 428 unique proteins in all CSF samples, we quantified 10 altered proteins with diverse biological functions after induction chemotherapy.

Conclusions

The levels of those 10 proteins change during the treatment of CNSL. Some of the proteins are likely to play a vital biological role as biomarkers for the development of ALL. In addition, our results indicated the feasible and reproducible utility of CSF for diagnosis and prognosis of patients with CNSL.

PGK1 facilities cisplatin chemoresistance by triggering HSP90/ERK pathway mediated DNA repair and methylation in endometrial endometrioid adenocarcinoma

Background

Endometrial carcinoma represents one of the most common cancer types of the female reproductive tract. If diagnosed at an early stage, the 5-year survival rate is promising. However, recurrence and chemoresistance remain problematic for at least 15% of the patients. In the present study, we aim to reveal the mechanism by which PGK1 regulates chemoresistance in endometrial carcinoma.

Methods

qPCR was performed to detect expression of PGK1 in clinical tissue samples of endometrial carcinoma. Specific shRNAs were employed to knockdown PGK1 expression in endometrial cancer cell lines. MTT assay was used to evaluate cell viability and cisplatin sensitivity of endometrial carcinoma cell lines. Western blot was performed to assess the effects of PGK1 knockdown on the expression levels of HSP90, DNA repair-associated proteins (c-JUN, FOSL1, and POLD1), and DNA methylation-related enzymes (DNMT1, DNMT3A and DNMT3B). Immunoprecipitation was performed to verify direct binding between PGK1 and HSP90.

Results

We first showed that PGK1 expression is elevated in tumor tissues of endometrial cancer, and high PGK1 levels are associated with clinical stages and metastasis. Knockdown of PGK1 inhibits proliferation of endometrial cancer cells, and enhances the inhibitory effect of cisplatin on cell viability. In addition, knockdown of PGK1 down-regulates the expression of DNA repair-related proteins, methylation-related enzymes, and total cellular methylation level. PGK1 was next shown to interact directly with HSP90 and exhibit pro-tumor effects by modulating the ATPase activity of HSP90.

Conclusions

We propose that PGK1 mediates DNA repair and methylation through the HSP90/ERK pathway, and eventually enhances the chemoresistance to cisplatin. The results provide new insights on functions of PGK1 and HSP90, which might make them as promising targets for endometrial cancer chemotherapy.

Downregulation of SPARC Is Associated with Epithelial-Mesenchymal Transition and Low Differentiation State of Biliary Tract Cancer Cells

BACKGROUND

Biliary tract cancers (BTCs) have a poor prognosis. BTCs are characterized by a prominent desmoplastic reaction which possibly contributes to the aggressive phenotype of this tumor. The desmoplastic reaction includes excessive production and deposition of extracellular matrix proteins such as periostin, secreted protein acidic and rich in cysteine (SPARC), thrombospondin-1, as well as accumulation of α-smooth muscle actin-positive cancer-associated fibroblasts and immune cells, secreting growth factors and cytokines including transforming growth factor (TGF)-β. In the present study, we investigated the expression of SPARC in BTC as well as its possible regulation by TGF-β.

METHODS

Expression levels of Sparc, TGF-β1 and its receptor ALK5 were evaluated by quantitative real-time PCR in 6 biliary tract cell lines as well as 1 immortalized cholangiocyte cell line (MMNK-1). RNAs from tumor samples of 7 biliary tract cancer patients were analyzed for expression of Sparc, TGF-β type II receptor (TbRII) as well as Twist and ZO-1. MMNK-1 cells were stimulated with TGF-β for 24 h, and Sparc, ZO-1 and E-Cadherin expressions were determined. The presence of SPARC protein was analyzed by immunohistochemistry in tumor specimens from 10 patients.

RESULTS

When comparing basal Sparc transcript levels in diverse BTC cell lines to MMNK-1 cells, we found that it was strongly downregulated in all cancer cell lines. The remaining expression levels were higher in highly differentiated cell lines (CCSW1, MZChA1, MZChA2 and TFK-1) than in less differentiated and undifferentiated ones (BDC, SKChA1). Expression of Sparc in BTC patient samples showed a significant positive correlation with expression of the epithelial marker ZO-1. In contrast, the mesenchymal marker Twist and the TbRII showed a trend of negative correlation with expression of Sparc in these samples. TGF-β exposure significantly downregulated Sparc expression in MMNK-1 cholangiocytes in vitro in parallel to downregulation of epithelial markers (E-Cadherin and ZO-1). Finally, SPARC immunostaining was performed in 10 patient samples, and the correlation between absence of SPARC and survival times was analyzed.

CONCLUSIONS

These data imply that a decrease in SPARC expression is correlated with dedifferentiation of BTC cells resulting in enhanced EMT being possibly mediated by TGF-β. Thereby SPARC levels might be a marker for individual prognosis of a patient, and strategies aiming at inhibition of SPARC downregulation might have potential for new future therapies.

Genome-scale analysis identifies SERPINE1 and SPARC as diagnostic and prognostic biomarkers in gastric cancer

Background

Gastric cancer (GC) is one of the most common types of malignancy and is associated with high morbidity and mortality rates around the world. With poor clinical outcomes, potential biomarkers for diagnosis and prognosis are important to investigate.

Objective

The aim of this study is to investigate the gene expression module of GC and to identify potential diagnostic and prognostic biomarkers.

Method

Microarray data (GSE13911, GSE29272, GSE54129, and GSE79973), including 293 stomach tumor tissues and 196 normal tissues, were analyzed to identify differentially expressed genes (DEGs). DEGs were identified in four profiles by intersecting four overlapping subsets, including 90 downregulated and 45 upregulated DEGs in common. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway analyses have been showed that extracellular matrix was the most enriched signal pathway. Furthermore, hub genes were analyzed by protein-protein interaction network and clinical outcomes were assessed by Kaplan-Meier survival analysis. Two independent datasets were used to validate the differential expression of two hub genes: Serpin Family E Member 1 (SERPINE1) and Secreted Protein Acidic and Cysteine Rich (SPARC).

Results

Validation of independent datasets indicated that SERPINE1 and SPARC expression were drastically increased in gastric tumor tissues and associated with poor outcomes in GC patients. The expression of SERPINE1 was related to race (Asian and White) (P< 0.05).

Conclusion

SERPINE1 and SPARC were significantly upregulated in gastric tissues and associated with poor outcomes. The investigations of SERPINE1 and SPARC may promote their predictive and prognostic value in GC.

SPARC: As a prognostic biomarker in rectal cancer patients treated with chemo-radiotherapy

BACKGROUND

The aim of this study is to search the prognostic value of SPARC expression in rectum cancer cases receiving postoperative radiotherapy.

METHODS

Forty three rectal cancer patients are recruited to this retrospective study. All patients received postoperative radiotherapy which the median dose was 5040 cGy and concomitant chemotherapy. Samples taken from their paraffin blocks were examined with immunohistochemical procedures.

RESULTS

When the association between SPARC expression and the clinicopathological feature was examined, there was a significant association between age and expression levels. Overall survival of patients with low expression was found to be 67 months whereas the overall survival of the patients with high expression was 32 months and the difference was statistically significant. Time to local recurrence of patients with low expression was found to be 74 months whereas time to local recurrence of the patients with high expression was 31 months. Progression free survival of the patients with low expression and high expression were 67 months and 32 months, respectively. In multivariate Cox regression analyses, high expression of SPARC was found to be associated with a statistically significant shorter overall survival and progression free survival.

CONCLUSIONS

High expression of SPARC is related to worse prognosis in rectal cancer patients.

A Contemporary Review of the Treatment Landscape and the Role of Predictive and Prognostic Biomarkers in Pancreatic Adenocarcinoma

Pancreatic cancer continues to represent one of the leading causes of cancer-related morbidity and mortality in the developed world. Over the past decade, novel systemic therapy combination regimens have contributed to clinically meaningful and statistically significant improvements in overall survival as compared to conventional monotherapy. However, the prognosis for most patients remains guarded secondary to the advanced stages of disease at presentation. There is growing consensus that outcomes can be further optimized with the use of predictive and prognostic biomarkers whereby the former can be enriching for patients who would benefit from therapies and the latter can inform decision-making regarding the need and timing of advanced care planning. One of the challenges of current biomarkers is the lack of standardization across clinical practices such that comparability between jurisdictions can be difficult or even impossible. This inconsistency can impede widespread implementation of their use. In this review article, we provide a comprehensive overview of the contemporary treatment options for pancreatic cancer and we offer some insights into the existing landscape and future directions of biomarker development for this disease.

Roles of SPARC in urothelial carcinogenesis, progression and metastasis

Secreted Protein Acidic and Rich in Cysteine (SPARC) is a matricellular glycoprotein that is implicated in myriad physiological and pathological conditions characterized by extensive remodeling and plasticity. The functions and disease association of SPARC in cancer is being increasingly appreciated as it plays multi-faceted contextual roles depending on the cancer type, cell of origin and the unique cancer milieu at both primary and metastatic sites. Herein we will review our current knowledge of the role of SPARC in the multistep cascades of urinary bladder carcinogenesis, progression and metastasis from preclinical models and clinical data and shine the light on its prognostic and therapeutic potentials.

SPARC is down-regulated by DNA methylation and functions as a tumor suppressor in T-cell lymphoma

The aim of this study was to assess the functional role of SPARC in T-cell non-Hodgkin's lymphoma (T-NHL), as well as the underlying molecular mechanisms. Here, we first identified SPARC expression in T-NHL tissues and cell lines through western blot and real-time PCR (RT-PCR). Overall survival of T-NHL patients with different levels of SPARC was assessed by Kaplan-Meier survival curves. Then cell proliferation, apoptosis, migration and invasion of T-NHL cells with either knockdown or overexpression of SPARC were determined by MTT, flow cytometry, transwell migration and invasion assay, respectively. Finally, the molecular mechanism by which SPARC modulated T-NHL cell progression was assessed. We confirmed that SPARC was significantly down-regulated in T-NHL tissues and cell lines. T-NHL patients with high levels of SPARC demonstrated a favorable clinical outcome. SPARC significantly suppressed cell proliferation, migration and invasion, and EMT process, but facilitated cell apoptosis in T-NHL cells. Further, we found that loss of SPARC expression in T-NHL tissues and cell lines, both in mRNA and protein levels, was associated with the aberrant DNA methylation in SPRAC gene, and the disrupted SPARC expression could be rescued after treatment with the demethylating agent 5-Aza-2'-deoxycitydine (5-Aza-Cdr). Additionally, 5-Aza-Cdr reversed SPARC hypermethylation to restore its biological role as a tumor suppressor in T-NHL cells, including inhibiting cell proliferation, invasion and migration, while promoting cell apoptosis. Our data provided evidence that DNA methylation in SPARC gene may play a role in the progression of T-NHL.

p16 Tumor Suppressor Gene Methylation in Diffuse Large B Cell Lymphoma: A Study of 88 Cases at Two Hospitals in the East Coast of Malaysia

Introduction: p16 gene plays an important role in the normal cell cycle regulation. Methylation of p16 has been reported to be one of the epigenetic events contributing to the pathogenesis of diffuse large B-cell lymphoma (DLBCL) which occurring at varying frequency. DLBCL is an aggressive and high-grade malignancy which accounts for approximately 30% of all non-Hodgkin lymphoma cases. However, little is known regarding the epigenetic alterations of p16 gene in DLBCL cases in Malaysia. Therefore, the objective of this study was to examine the status of p16 methylation in DLBCL. Methods: A total of 88 formalin-fixed paraffin-embedded DLBCL tissues retrieved from two hospitals located in the east coast of Malaysia, namely Hospital Tengku Ampuan Afzan (HTAA) Pahang and Hospital Universiti Sains Malaysia (HUSM) Kelantan, were chosen for this study. DNA specimens were isolated and subsequently subjected to bisulfite treatment prior to methylation specific-PCR. Two pairs of primers were used to amplify methylated and unmethylated regions of p16 gene. The PCR products were then separated using agarose gel electrophoresis and visualised under UV illumination. SPSS version 12.0 was utilised to perform all statistical analysis. Result: p16 methylation was detected in 65 of 88 (74%) samples. There was a significant association between p16 methylation status and patients aged >50 years old (p=0.04). Conclusion: Our study demonstrated that methylation of p16 tumor suppressor gene in our DLBCL cases is common and significantly increased among patients aged 50 years and above. Aging is known to be an important risk factor in the development of cancers and we speculate that this might be due to the increased transformation of malignant cells in aging cell population. However, this has yet to be confirmed with further research and correlate the findings with clinicopathological parameters.

Self-Targeting, Immune Transparent Plasma Protein Coated Nanocomplex for Noninvasive Photothermal Anticancer Therapy

Cancer cells exhibit specific physiological differences compared to normal cells. Most surface membranes of cancer cells are characterized by high expression of given protein receptors, such as albumin, transferrin, and growth factors that are also present in the plasma of patients themselves, but are lacking on the surface of normal cells. These distinct features between cancer and normal cells can serve as a niche for developing specific treatment strategies. Near-infrared (NIR)-light-triggered therapy platforms are an interesting novel avenue for use in clinical nanomedicine. As a photothermal agent, conducting polymer nanoparticles, such as polypyrrole (PPy), of great NIR light photothermal effects and good biocompatibility, show promising applications in cancer treatments through the hyperthermia mechanism. Autologous plasma proteins coated PPy nanoparticles for hyperthermia therapy as a novel core technology platform to treat cancers through secreted protein acid and rich in cysteine targeting are developed here. This approach can provide unique features of specific targeting toward cancer cell surface markers and immune transparency to avoid recognition and attack by defense cells and achieve prolonged circulation half-life. This technology platform unveils new clinical options for treatment of cancer patients, supporting the emergence of innovative clinical products.

Decorin gene upregulation mediated by an adeno-associated virus vector increases intratumoral uptake of nab-paclitaxel in neuroblastoma via inhibition of stabilin-1

The availability of effective medication for the treatment of refractory or recurrent neuroblastoma remains limited. This study sought to investigate the effects of increased decorin (DCN) expression on the intratumoral uptake of nab-paclitaxel as a potential novel approach to NB. Correlation between the clinical characteristics of neuroblastoma and the expression of DCN, secreted protein acidic and rich in cysteine (SPARC) and stabilin-1 was evaluated. The anticancer effect of recombinant adeno-associated virus-DCN (rAAV-DCN) was assessed in vivo and in vitro. And the effect of rAAV-DCN on the intratumoral uptake of paclitaxel was also studied in neuroblastoma-grafted nude mice. Overall, 12.5%, 17.7%, and 71.9% of the tumors stained positive for DCN, SPARC and stabilin-1 respectively and correlated to age, stage and N-MYC status in 96 children and adolescents with neuroblastoma. Transfected neuroblastoma cells stably expressed DCN, with in vivo and in vitro studies demonstrating rAAV-DCN sensitized the anticancer effect of nab-paclitaxel. Systemic rAAV-DCN in neuroblastoma-grafted nude mice inhibited stabilin-1, up-regulated SPARC, and increased the intratumoral uptake of paclitaxel. Macrophage depletion or anti-stabilin-1 monoclonal antibody increased the intratumoral uptake of nab-paclitaxel and its anticancer effects to a degree comparable to that achieved by systemic rAAV-DCN. The systemic administration of rAAV-DCN up-regulates DCN in neuroblastoma and accelerates the intratumoral uptake of nab-paclitaxel by inhibiting stabilin-1 mediated SPARC degradation.

A phase I trial of azacitidine and nanoparticle albumin bound paclitaxel in patients with advanced or metastatic solid tumors

Background

Secreted protein acidic and rich in cysteine (SPARC), an albumin-binding protein, is downregulated by hypermethylation in many cancers. Hypomethylating agents such as azacitidine can upregulate SPARC in tumors, which may enhance the accumulation of albumin-bound drugs at tumor site. The objectives of this phase I trial was to determine the safety and maximum tolerated dose and to assess any clinical activity of the combination of azacytidine and weekly nanoparticle-albumin-bound (nab®) paclitaxel.

Methods

Patients received escalating azacytidine doses daily for 5 days, followed by nab-paclitaxel at the standard 100mg/m2 weekly dose for 3 weeks in 4-week cycles. Dose-limiting toxicities (DLTs) were monitored during the first cycle. Serum was obtained at baseline, during and after treatment for correlative study.

Results

All sixteen total patients enrolled were evaluable for toxicity, while 13 patients were evaluable for response. Two of five patients treated with 100mg/m2 of azacytidine had DLT of prolonged grade 4 neutropenia. Therefore, the MTD of azacitidine in this regimen is 75 mg/m². Three additional patients were treated with no grade 4 toxicity in cycle 1. Clinical activity included 1 complete response (CR) in refractory DLBCL, 2 CR in ovarian cancer, 4 partial responses (PR) in ovarian and endometrial cancer, 4 stable diseases (SD) in lung, sarcoma and pancreatic cancer, 1 unconfirmed PR in breast cancer, and 1 progression of disease in CLL/SLL.

Conclusions

Priming with azacitidine 75 mg/m² daily for 5 days, followed by weekly nab-paclitaxel 100 mg/m² weekly was well tolerated and results in dramatic responses pre-treated cancer patients.

Olfactomedin 1 negatively regulates NF-κB signalling and suppresses the growth and metastasis of colorectal cancer cells

Uncontrolled growth and distant metastasis are hallmarks of colorectal cancer (CRC), but the mechanisms are poorly understood. Olfactomedin 1 (OLFM1), a member of the olfactomedin domain-containing protein family, plays an important role in the development of neurogenic tissues. Recently, OLFM1 deregulation was frequently observed in several cancers, and it was induced in colon cell lines after treatment with the demethylating agent 5-aza-2'-deoxycytidine. However, the function of OLFM1 in CRC remains unknown. In this study, we reanalysed published microarray data and found that OLFM1 was significantly down-regulated in primary CRC samples compared to adjacent non-cancerous tissues. The results of immunohistochemistry indicated that decreased OLFM1 expression was significantly associated with lymph node status (p = 0.023), distant metastasis (p < 0.001), and AJCC/TNM stage (p = 0.013), and CRC patients with low OLFM1 expression had consistently poor overall survival (OS; p < 0.001) and progression-free survival (PFS; p < 0.001). Further analysis demonstrated that OLFM1 was epigenetically silenced in CRC tissues and cell lines via promoter hypermethylation. Overexpression and knockdown of OLFM1 attenuated and increased, respectively, CRC cells' proliferation, migration, and invasion in vitro and metastasis to the lung and liver in vivo. Mechanistically, the promotion of growth and metastasis of CRC cells by silencing of OLFM1 was associated with the activation of the non-canonical NF-κB signalling pathway. OLFM1 interacted with NF-κB-inducing kinase (NIK; MAP3K14) and repressed the phosphorylation of its downstream substrate Ikappa B kinase alpha (IKKα). OLFM1 expression was negatively correlated with the phosphorylation level of IKKα in CRC tissue samples. Knockdown of NIK impaired the ability of OLFM1 to repress NF-κB signalling, cell growth or migration. Thus, OLFM1 may be a valuable biomarker and therapeutic target for CRC patients. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Molecular profiling of 6,892 colorectal cancer samples suggests different possible treatment options specific to metastatic sites

Metastatic colorectal cancer (mCRC) carries a poor prognosis with an overall 5-year survival of 13.1%. Therapies guided by tumor profiling have suggested benefit in advanced cancer. We used a multiplatform molecular profiling (MP) approach to identify key molecular changes that may provide therapeutic options not typically considered in mCRC. We evaluated 6892 mCRC referred to Caris Life Sciences by MP including sequencing (Sanger/NGS), immunohistochemistry (IHC) and in-situ hybridization (ISH). mCRC metastases to liver, brain, ovary or lung (n = 1507) showed differential expression of markers including high protein expression of TOPO1 (52%) and/or low RRM1 (57%), TS (71%) and MGMT (39%), suggesting possible benefit from irinotecan, gemcitabine, 5FU/capecitabine and temozolomide, respectively. Lung metastases harbored a higher Her2 protein expression than the primary colon tumors (4% vs. 1.8%, p = 0.028). Brain and lung metastases had higher KRAS mutations than other sites (65% vs 59% vs 47%, respectively, p = 0.07, <0.01), suggesting poor response to anti-EGFR therapies. BRAF-mutated CRC (n = 455) showed coincident high protein expression of RRM1 (56%), TS (53%) and low PDGFR (22%) as compared with BRAF wild-type tumors. KRAS-mutated mCRC had higher protein expression of c-MET (47% vs. 36%) and lower MGMT (56% vs. 63%), suggesting consideration of c-MET inhibitors and temozolomide. KRAS-mutated CRC had high TUBB3 (42% vs. 33%) and low Her2 by IHC (0.5%) and HER2 by FISH (3%, p <0.05). CRC primaries had a lower incidence of PIK3CA and BRAF mutations in rectal cancer versus colon cancer (10% and 3.3%, respectively). MP of 6892 CRCs identified significant differences between primary and metastatic sites and among BRAF/KRAS sub-types. Our findings are hypothesis generating and need to be examined in prospective studies. Specific therapies may be considered for different actionable targets in mCRC as revealed by MP.

SPARC Promotes Cell Invasion In Vivo by Decreasing Type IV Collagen Levels in the Basement Membrane

Overexpression of SPARC, a collagen-binding glycoprotein, is strongly associated with tumor invasion through extracellular matrix in many aggressive cancers. SPARC regulates numerous cellular processes including integrin-mediated cell adhesion, cell signaling pathways, and extracellular matrix assembly; however, the mechanism by which SPARC promotes cell invasion in vivo remains unclear. A main obstacle in understanding SPARC function has been the difficulty of visualizing and experimentally examining the dynamic interactions between invasive cells, extracellular matrix and SPARC in native tissue environments. Using the model of anchor cell invasion through the basement membrane (BM) extracellular matrix in Caenorhabditis elegans, we find that SPARC overexpression is highly pro-invasive and rescues BM transmigration in mutants with defects in diverse aspects of invasion, including cell polarity, invadopodia formation, and matrix metalloproteinase expression. By examining BM assembly, we find that overexpression of SPARC specifically decreases levels of BM type IV collagen, a crucial structural BM component. Reduction of type IV collagen mimicked SPARC overexpression and was sufficient to promote invasion. Tissue-specific overexpression and photobleaching experiments revealed that SPARC acts extracellularly to inhibit collagen incorporation into BM. By reducing endogenous SPARC, we also found that SPARC functions normally to traffic collagen from its site of synthesis to tissues that do not express collagen. We propose that a surplus of SPARC disrupts extracellular collagen trafficking and reduces BM collagen incorporation, thus weakening the BM barrier and dramatically enhancing its ability to be breached by invasive cells.

SPARC Expression Is Selectively Suppressed in Tumor Initiating Urospheres Isolated from As+3- and Cd+2-Transformed Human Urothelial Cells (UROtsa) Stably Transfected with SPARC

BACKGROUND

This laboratory previously analyzed the expression of SPARC in the parental UROtsa cells, their arsenite (As(+3)) and cadmium (Cd(+2))-transformed cell lines, and tumor transplants generated from the transformed cells. It was demonstrated that SPARC expression was down-regulated to background levels in Cd(+2)-and As(+3)-transformed UROtsa cells and tumor transplants compared to parental cells. In the present study, the transformed cell lines were stably transfected with a SPARC expression vector to determine the effect of SPARC expression on the ability of the cells to form tumors in immune-compromised mice.

METHODS

Real time PCR, western blotting, immunohistochemistry, and immunofluorescence were used to define the expression of SPARC in the As(+3)-and Cd(+2)-transformed cell lines, and urospheres isolated from these cell lines, following their stable transfection with an expression vector containing the SPARC open reading frame (ORF). Transplantation of the cultured cells into immune-compromised mice by subcutaneous injection was used to assess the effect of SPARC expression on tumors generated from the above cell lines and urospheres.

RESULTS

It was shown that the As(+3)-and Cd(+2)-transformed UROtsa cells could undergo stable transfection with a SPARC expression vector and that the transfected cells expressed both SPARC mRNA and secreted protein. Tumors formed from these SPARC-transfected cells were shown to have no expression of SPARC. Urospheres isolated from cultures of the SPARC-transfected As(+3)-and Cd(+2)-transformed cell lines were shown to have only background expression of SPARC. Urospheres from both the non-transfected and SPARC-transfected cell lines were tumorigenic and thus fit the definition for a population of tumor initiating cells.

CONCLUSIONS

Tumor initiating cells isolated from SPARC-transfected As(+3)-and Cd(+2)-transformed cell lines have an inherent mechanism to suppress the expression of SPARC mRNA.

Expression of secreted protein acidic and rich in cysteine is an independent prognostic indicator of a poor clinical outcome in oropharyngeal carcinoma patients

CONCLUSION

SPARC-expression is an indicator of the prognosis in terms of OS, independent of HPV-infection. HPV-negative patients with SPARC-Low show survival as favorable as HPV-positive patients, probably because of their higher salvage rate after relapse than SPARC-High patients.

OBJECTIVE

The objectives of the study were to clarify the correlation between the expression of secreted protein acidic and rich in cysteine (SPARC) and HPV-status, and to determine the prognostic value of SPARC-expression in oropharyngeal squamous cell carcinoma (OPSCC) patients.

METHODS

Fifty-three formalin-fixed and paraffin-embedded tissues were obtained from patients with OPSCC who underwent curative treatment. The SPARC protein was detected by immunohistochemistry. SPARC-expression level was divided into two categories, SPARC-High and SPARC-Low, according to the staining index.

RESULTS

Twenty-two out of the 53 OPSCC patients were HPV-positive. There was no significant correlation between the HPV-status and SPARC-expression level. Multivariate Cox proportional hazards regression analysis revealed that the HPV-status and SPARC-expression are independent prognostic indicators of favorable and unfavorable overall survival (OS) (p = 0.021 and p = 0.012), respectively. For disease-free survival, the HPV-status was the only predictive factor (p = 0.022). After stratification by the HPV-status, high SPARC-expression was a significant predictor of poor OS in HPV-negative OPSCC patients using Kaplan-Meier analysis and the log-rank test (p = 0.014). Ten out of 28 SPARC-Low patients relapsed, among which six patients (60%) were salvaged. However, 14 out of 25 SPARC-High patients relapsed, and only three patients (21.4%) were salvaged.

Matricellular protein SPARC/osteonectin expression is regulated by DNA methylation in its core promoter region

BACKGROUND

SPARC/osteonectin is an evolutionarily conserved matricellular protein that modulates cell-matrix interaction and cell function. In all vertebrates, SPARC is dynamically expressed during embryogenesis. However, the precise function of SPARC and the regulatory elements required for its expression in particular during early embryogenesis are largely unknown.

RESULTS

The present study was undertaken to explore the molecular mechanisms that regulate sparc gene expression by in vivo functional characterization of the sparc promoter and identification of possible putative regulatory elements that govern basal promoter activity. We report here transient expression analyses of eGFP expression from transgenic zebrafish containing a Sparc-iTol2-eGFP-BAC and/or 7.25 kb-sparc-Tol2-eGFP constructs. eGFP expression was specifically found in the notochord, otic vesicle, fin fold, intermediate cell mass, and olfactory placode of BAC and Tol2 transposon vectors injected embryos. Deletion analysis revealed that promoter activity resides in the unique 5'-untranslated intronic region. Computer-based analysis revealed a putative CpG island immediately proximal to the translation start site within the intron sequence. Global inhibition of methylation with 5-Aza-2-deoxycytidine promoted sparc expression in association with decreasing CpG methylation.

CONCLUSIONS

Taken together, these data identify a contributory role for DNA methylation in regulating sparc expression in zebrafish embryogenesis.

Aberrant methylation of the SPARC gene promoter and its clinical implication in gastric cancer

Secreted protein acidic and rich in cysteine (SPARC) gene has been shown to be epigenetically silenced in several cancers. We investigated the loss of expression and promoter methylation of this tumor suppressor gene in gastric cancers and correlated the data with clinicopathological features. We observed the loss of SPARC mRNA and SPARC protein expression in 7 of 10 (70%) gastric cancer cell lines. Upon treatment of expression-negative cell lines with a demethylating agent, expression of mRNA and protein was restored in all cells. Methylation rate of SPARC gene was 80% in ten gastric cancer cell lines and 74% (163 of 220) in primary tumors, while it was 5% in normal gastric mucosa (n = 40). In intestinal gastric cancer, SPARC methylation correlated with a negative prognosis (P < 0.001; relative risk 2.754, 95% confidence interval 1.780–4.261). Immunostaining revealed that SPARC protein was overexpressed in stromal fibroblasts adjacent to neoplastic epithelium but rarely expressed in the primary gastric cancer cells. These results implicate SPARC promoter methylation as an important factor in the tumorigenesis of gastric carcinomas and provide new insights into the potential use of SPARC as a novel biomarker and the potential clinical importance in human gastric cancers.

Stromal expression of SPARC in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) stands as the poorest prognostic tumor of the digestive tract, with a 5-year survival rate of less than 5%. Therapeutic options for unresectable PDAC are extremely limited and there is a pressing need for expanded therapeutic approaches to improve current options available with gemcitabine-based regimens. With PDAC displaying one of the most prominent desmoplastic stromal reactions of all carcinomas, recent research has focused on the microenvironment surrounding PDAC cells. Secreted protein acid and rich in cysteine (SPARC), which is overexpressed in PDAC, may display tumor suppressor functions in several cancers (e.g., in colorectal, ovarian, prostate cancers, and acute myelogenous leukemia) but also appears to be overexpressed in other tumor types (e.g., breast cancer, melanoma, and glioblastoma). The apparent contradictory functions of SPARC may yield inhibition of angiogenesis via inhibition of vascular endothelial growth factor, while promoting epithelial-to-mesenchymal transition and invasion through matrix metalloprotease expression. This feature is of particular interest in PDAC where SPARC overexpression in the stroma stands along with inhibition of angiogenesis and promotion of cancer cell invasion and metastasis. Several therapeutic strategies to deplete stromal tissue have been developed. In this review, we focused on key preclinical and clinical data describing the role of SPARC in PDAC biology, the properties, and mechanisms of delivery of drugs that interact with SPARC and discuss the proof-of-concept clinical trials using nab-paclitaxel.

Role of SPARC in bone remodeling and cancer-related bone metastasis

There is a growing socioeconomic recognition that clinical bone diseases such as bone infections, bone tumors and osteoporotic bone loss mainly associated with ageing, are major issues in today's society. SPARC (secreted protein, acidic and rich in cysteine), a matricellular glycoprotein, may be a promising therapeutic target for preventing or treating bone-related diseases. In fact, SPARC is associated with tissue remodeling, repair, development, cell turnover, bone mineralization and may also participate in growth and progression of tumors, namely cancer-related bone metastasis. Yet, the function of SPARC in such biological processes is poorly understood and controversial. The main objective of this work is to review the current knowledge related to the activity of SPARC in bone remodeling, tumorigenesis, and bone metastasis. Progress in understanding SPARC biology may provide novel strategies for bone regeneration and the development of anti-angiogenic, anti-proliferative, or counter-adhesive treatments specifically against bone metastasis.

SPARC/osteonectin is involved in metastatic process to the lung during melanoma progression

The existence of a "metastasis gene signature" that predisposes primary breast cancer cells to metastasize to the lungs has been recently highlighted by gene expression profiling studies. The combination of genes responsible for this process includes genes encoding several metalloproteinases as well as the gene encoding SPARC (secreted protein acidic and rich in cysteine)/osteonectin. SPARC is involved in normal tissue remodeling as it regulates the deposition of extracellular matrix, but also plays a role in neoplastic transformation. Aberrant SPARC expression has been detected both in stromal cells associated with cancer and in cancer cells. The main aim of this study was to investigate whether or not SPARC might be involved in directing metastasis of other types of cancer to the lung. We constructed a tissue microarray containing lung metastases from a variety of primary tumors in different organs and used immunohistochemistry to assess SPARC expression. We found SPARC overexpressed mainly in lung metastases from melanoma. We then assessed the expression of SPARC mRNA and protein in metastatic melanoma from different anatomic sites and in their corresponding primary tumors, and found that it is overexpressed in lung metastases. Our data strongly support the hypothesis that SPARC is involved in directing melanoma metastases specifically to the lung, which underpins its potential as prognostic marker and novel target for specific therapy.

Differential survival trends of stage II colorectal cancer patients relate to promoter methylation status of PCDH10, SPARC, and UCHL1

Surgical excision of colorectal cancer at early clinical stages is highly effective, but 20-30% of patients relapse. Therefore, it is of clinical relevance to identify patients at high risk for recurrence, who would benefit from adjuvant chemotherapy. The objective of this study was to identify prognostic and/or predictive methylation markers in stage II colorectal cancer patients. Therefore, we selected six gene promoters (FZD9, PCDH10 (protocadherin 10), SFRP2, SPARC (secreted protein acidic and rich in cysteine), UCHL1 (ubiquitin carboxyl-terminal hydrolase 1), and WIF1) for methylation analysis in formalin-fixed, paraffin-embedded primary tumor samples of colorectal cancer patients (n=143) who were enrolled in a prospective randomized phase III trial of the Austrian Breast and Colorectal cancer Study Group. Patients were randomized to adjuvant chemotherapy with 5-fluorouracil and leucovorin or surveillance only. Survival analyses revealed that combined evaluation of three promoters (PCDH10, SPARC, and UCHL1) showed differential effects with regard to disease-free survival and overall survival in the two treatment groups (significance level 0.007). In the chemotherapy arm, a statistically insignificant trend for patients without methylation toward longer survival was observed (P=0.069 for disease-free survival and P=0.139 for overall survival). Contrary, patients in the surveillance arm without methylation in their gene promoters had shorter disease-free survival and overall survival (P=0.031 for disease-free survival and P=0.003 for overall survival), indicating a prognostic effect of methylation in this group (test for interaction, P=0.006 for disease-free survival and P=0.018 for overall survival). These results indicate that promoter methylation status of PCDH10, SPARC, and UCHL1 may be used both as prognostic and predictive molecular marker for colorectal cancer patients and, therefore, may facilitate treatment decisions for stage II colorectal cancer.

SPARC was overexpressed in human endometrial cancer stem-like cells and promoted migration activity

OBJECTIVES

We previously demonstrated that side-population (SP) cells found in human endometrial cancer tissue have features of cancer stem cells (CSCs). Endometrial cancer SP cells show enhanced migration, the potential to differentiate into the mesenchymal cell lineage, and they are associated with the epithelial-mesenchymal transition (EMT). In this study, we analyzed the expression and function of a specific protein, SPARC (secreted protein acidic and rich in cysteine) which we found to be up-regulated in endometrial cancer.

METHODS

We performed microarray expression analysis to screen for up-regulated genes in CSCs using a set of RK12V-SP cells and -non-SP (NSP) cells. We used the MetaCore package to identify the Gene GO pathway MAPs associated with the up-regulated genes. Here, we investigated the expression and functions of SPARC, one of the genes up-regulated in endometrial CSCs. We established SPARC-overexpressing cells by transfecting endometrial cancer cells (Ishikawa cells [IK-SPARC cells]). We characterized these cells' growth rate, tumorigenicity, migration and invasion activity. The levels and locations of SPARC protein expression in Hec1SP cells-derived tumors and endometrial cancer tissues were examined by immunohistochemistry.

RESULTS

SPARC was detected by microarray expression analysis during screens for up-regulated genes in SP and NSP CSC. The level of SPARC expression was enhanced in Hec1 SP cells compared with that in Hec1 non-SP cells. SPARC enhanced fibronectin expression and promoted migration activity in IK cells. SPARC expression suppressed tumor growth but promoted formation of tumor stroma. SPARC was expressed in endometrial cancer tissues, in particular, poorly differentiated endometrioid adenocarcinoma, clear and serous adenocarcinoma,but not in normal endometrial tissue.

CONCLUSION

This is the first report of overexpression of SPARC in endometrial cancer stem-like cells. SPARC expression is associated with cell migration and stroma formation.

Molecular mechanisms underlying the divergent roles of SPARC in human carcinogenesis

Communication between the cell and its surrounding environment, consisting of proteinaceous (non-living material) and extracellular matrix (ECM), is important for biophysiological and chemical signaling. This signaling results in a range of cellular activities, including cell division, adhesion, differentiation, invasion, migration and angiogenesis. The ECM non-structural secretory glycoprotein called secreted protein, acidic and rich in cysteine (SPARC), plays a significant role in altering cancer cell activity and the tumor's microenvironment (TME). However, the role of SPARC in cancer research has been the subject of controversy. This review mainly focuses on recent advances in understanding the contradictory nature of SPARC in relation to ECM assembly, cancer cell proliferation, adhesion, migration, apoptosis and tumor growth.

SPARC promotes leukemic cell growth and predicts acute myeloid leukemia outcome

Aberrant expression of the secreted protein, acidic, cysteine-rich (osteonectin) (SPARC) gene, which encodes a matricellular protein that participates in normal tissue remodeling, is associated with a variety of diseases including cancer, but the contribution of SPARC to malignant growth remains controversial. We previously reported that SPARC was among the most upregulated genes in cytogenetically normal acute myeloid leukemia (CN-AML) patients with gene-expression profiles predictive of unfavorable outcome, such as mutations in isocitrate dehydrogenase 2 (IDH2-R172) and overexpression of the oncogenes brain and acute leukemia, cytoplasmic (BAALC) and v-ets erythroblastosis virus E26 oncogene homolog (ERG). In contrast, SPARC was downregulated in CN-AML patients harboring mutations in nucleophosmin (NPM1) that are associated with favorable prognosis. Based on these observations, we hypothesized that SPARC expression is clinically relevant in AML. Here, we found that SPARC overexpression is associated with adverse outcome in CN-AML patients and promotes aggressive leukemia growth in murine models of AML. In leukemia cells, SPARC expression was mediated by the SP1/NF-κB transactivation complex. Furthermore, secreted SPARC activated the integrin-linked kinase/AKT (ILK/AKT) pathway, likely via integrin interaction, and subsequent β-catenin signaling, which is involved in leukemia cell self-renewal. Pharmacologic inhibition of the SP1/NF-κB complex resulted in SPARC downregulation and leukemia growth inhibition. Together, our data indicate that evaluation of SPARC expression has prognosticative value and SPARC is a potential therapeutic target for AML.

Expression analysis of SPARC/osteonectin in oral squamous cell carcinoma patients: from saliva to surgical specimen

Oral squamous cell carcinoma (OSCC) remains a significant cause of morbidity and mortality, with approximately 540,000 new cases annually worldwide. The molecular mechanisms related to the pathogenesis of this disease are still poorly understood. The discovery of a molecular marker that allows the early detection of this cancer, which can be easily identified in biological samples, such as saliva, without intervening in advanced stages, is a challenge. Numerous studies have identified a panel of molecular markers differently expressed in OSCC and normal oral mucosa. In particular, it was found an aberrant expression of matricellular glycoprotein SPARC. SPARC is involved in normal tissue remodeling, regulating the deposition of extracellular matrix, but also in neoplastic transformation. In fact, aberrant SPARC expression was detected both in stromal cells associated with cancer and in tumor cells. The aim of our study was the evaluation of SPARC on a retrospective series of 119 OSCC cases and the validation of the obtained data on a prospective series of 27 patients with OSCC, of whom we have previously collected saliva, and smeared material. The obtained results were correlated with each other and with clinical pathological parameters at our disposal. The study demonstrated a prognostic value of SPARC, especially with regard to its expression in the stroma surrounding OSCC (P < 0.05).

Expression of Secreted Protein Acidic and Rich in Cysteine in the Stroma of a Colorectal Carcinoma is Associated With Patient Prognosis

Purpose

Secreted protein acidic and rich in cysteine (SPARC), also known as osteonectin or basement-membrane-40 (BM-40), is a member of a family of matricellular proteins, whose functions are to modulate cell-matrix interactions, growth and angiogenesis in colorectal cancer. In this study, the expression of SPARC was evaluated and its correlations with clinicopathological parameters were investigated.

Methods

The researchers analyzed the expression patterns of SPARC by using immunohistochemistry in 332 cases of colorectal cancer of tissue microarray. The clinicopathological characteristics were defined by using the TNM criteria of the Union for International Cancer Control. Clinicopathological factors such as age, sex, histologic type of the tumor, pathologic tumor stage, TNM stage, and lymphovascular invasion were evaluated according to the SPARC expression.

Results

The hazard ratios expressing SPARC in tumor cells, in the stroma, and in both tumor cells and the stroma were 2.10 (P = 0.036), 3.27 (P = 0.003) and 2.12 (P = 0.038), respectively. Patient survival was decreased in patient expressing SPARC in the stroma, and this result showed statistical significance (P = 0.016).

Conclusion

These findings suggest that SPARC expression in a tumor and in the stroma correlates with disease progression and may be used as a prognostic marker for colorectal cancer.

The expression of SPARC in human intracranial aneurysms and its relationship with MMP-2/-9

Objective

SPARC is a key determinant of invasion and metastasis in some tumors, such as gliomas, melanomas and prostate tumors. SPARC can change the composition and structure of the matrix and promote angiogenesis; these effects are closely related to clinical stage and the prognosis of tumors such as meningiomas. However, little is known about the expression of SPARC in intracranial aneurysms. The goal of this study was to establish the role of SPARC in human intracranial aneurysms.

Methods

Thirty-one intracranial aneurysms were immunohistochemically stained for SPARC, MMP-2 and MMP-9. As controls, normal Circle of Willis arteries were similarly immunostained. All specimens were retrieved during autopsies and were embedded in paraffin. To evaluate the expression levels of SPARC, MMP-2 and MMP-9, western blotting was also performed in three available intracranial aneurysm specimens. The limited availability of fresh intracranial aneurysm tissue was the result of the majority of patients choosing endovascular embolization.

Results

The results showed that SPARC, MMP-2 and MMP-9 were strongly expressed in intracranial aneurysm tissues; however, these proteins were expressed minimally or not at all in normal Circle of Willis arteries. The western blot results showed that the expression levels of SPARC, MMP-2 and MMP-9 were significantly up-regulated in intracranial aneurysms relative to the expression levels in the normal Circle of Willis arteries. Data analysis showed that SPARC was significantly correlated with MMP-2 and MMP-9, also with age and risk factors but not with the Hunt-Hess grade or with sex.

Conclusion

The results indicate that SPARC is widely expressed in human intracranial aneurysms, and its expression correlates with MMP-2 and MMP-9 expression, age and risk factors but not with the Hunt-Hess grade. The results of this study suggest that SPARC has a pathogenic role in the alteration of the extracellular matrix of intracranial arteries during aneurysm formation.