Serum CRP interacts with SPARC and regulate immune response in severe cases of COVID-19 infection

Serum C-reactive protein (CRP) has been found elevated during COVID-19 infection, and associated with systematic inflammation as well as a poor clinical outcome. However, how did CRP participated in the COVID-19 pathogenesis remains poorly understood. Here, we report that serum C-reactive protein (CRP) levels are correlated with megakaryocyte marker genes and could regulate immune response through interaction with megakaryocytes. Molecular dynamics simulation through ColabFold showed a reliable interaction between monomeric form of CRP (mCRP) and the secreted protein acidic and rich in cysteine (SPARC). The interaction does not affect the physiological activities of SPARC while would be disturbed by pentamerization of CRP. Interplay between SPARC and mCRP results in a more intense immune response which may led to poor prognosis. This study highlights the complex interplay between inflammatory markers, megakaryocytes, and immune regulation in COVID-19 and sheds light on potential therapeutic targets.

Hepatic SPARC Expression Is Associated with Inflammasome Activation during the Progression of Non-Alcoholic Fatty Liver Disease in Both Mice and Morbidly Obese Patients

The severity of non-alcoholic fatty liver disease (NAFLD) ranges from simple steatosis to steatohepatitis, and it is not yet clearly understood which patients will progress to liver fibrosis or cirrhosis. SPARC (Secreted Protein Acidic and Rich in Cysteine) has been involved in NAFLD pathogenesis in mice and humans. The aim of this study was to investigate the role of SPARC in inflammasome activation, and to evaluate the relationship between the hepatic expression of inflammasome genes and the biochemical and histological characteristics of NAFLD in obese patients. In vitro studies were conducted in a macrophage cell line and primary hepatocyte cultures to assess the effect of SPARC on inflammasome. A NAFLD model was established in SPARC knockout (SPARC-/-) and SPARC+/+ mice to explore inflammasome activation. A hepatic RNAseq database from NAFLD patients was analyzed to identify genes associated with SPARC expression. The results were validated in a prospective cohort of 59 morbidly obese patients with NAFLD undergoing bariatric surgery. Our results reveal that SPARC alone or in combination with saturated fatty acids promoted IL-1β expression in cell cultures. SPARC-/- mice had reduced hepatic inflammasome activation during the progression of NAFLD. NAFLD patients showed increased expression of SPARC, NLRP3, CASP1, and IL-1β. Gene ontology analysis revealed that genes positively correlated with SPARC are linked to inflammasome-related pathways during the progression of the disease, enabling the differentiation of patients between steatosis and steatohepatitis. In conclusion, SPARC may play a role in hepatic inflammasome activation in NAFLD.

Association Between SPARC Polymorphisms and Ankylosing Spondylitis and Its mRNA and Protein Expression in a Chinese Han Population: A Case-Control Study

Objective

We explore the association of polymorphisms in Secreted protein acidic and rich in cysteine (SPARC) with ankylosing spondylitis (AS) and detect SPARC mRNA and protein expression in a Chinese Han population.

Methods

Nine single-nucleotide polymorphisms (SNPs) of SPARC were genotyped in 768 AS patients and 768 controls by TaqMan genotyping assay. mRNA expression of SPARC was detected by real-time polymerase chain reaction (RT-PCR), and serum level of SPARC protein was detected by ELISA.

Results

The frequency of A allele of rs171121187 was significantly higher in AS patients than in controls (Pc=0.003, odds ratio [OR]=1.45, 95% confidence interval [95% CI] = 1.18-1.77), the AA and AC genotypes increased the risk of AS when compared with CC genotype (Pc=0.003, OR=3.96, 95% CI=1.80-8.75, and Pc=0.003, OR=1.27, 95% CI=1.01-1.61, respectively). The frequency of G allele of rs4958487 was significantly lower in AS than in controls (Pc=0.001, OR=0.60, 95% CI=0.47-0.68), the GG and GA genotypes reduced the risk of AS when compared with AA genotype (Pc=0.005, OR=0.46, 95% CI 0.18-1.14, and Pc=0.005, OR=0.60, 95% CI=0.45-0.79, respectively). The haplotype AA of rs17112187/rs4958487 significantly increased the risk of AS (P=2.31E-5, OR=1.60, 95% CI=1.28-1.98), while haplotype CG decreased the risk of AS (P=5.42E-5, OR=0.55, 95% CI=0.41-0.74). Expression levels of SPARC mRNA were significantly lower in both Peripheral blood mononuclear cells (PBMC) and granulocytes in AS patients than in controls (P=0.008 and P=0.005, respectively). SPARC protein levels were also reduced in AS patients versus the controls (P=0.002).

Conclusion

This study indicates that polymorphisms in SPARC are associated with AS susceptibility, and both mRNA and protein levels of SPARC are decreased in AS patients in a Chinese Han population.

SPARC is a decoy counterpart for c‑Fos and is associated with osteoblastic differentiation of bone marrow stromal cells by inhibiting adipogenesis

Secreted protein acidic and rich in cysteine (SPARC), also called basement‑membrane protein 40 or osteonectin, is a matricellular protein that is abundant not only in bone tissue as a non‑collagenous protein but is also ubiquitously expressed in non‑calcified tissue. SPARC is located intracellularly and disruption of the Sparc gene has been reported to reduce bone formation and increase fat tissue; however, the mechanism by which SPARC inhibits adipogenesis remains unclear. The present study evaluated the intracellular function of SPARC in adipogenesis using the bone marrow stromal cell line ST2. When ST2 cells with low SPARC production were cloned, intrinsic activator protein‑1 (AP‑1) activity was markedly higher, mineralized nodule formation was significantly lower and lipid accumulation was significantly increased compared with in the parental ST2 cells. Forced expression of secreted SPARC with the signal peptide‑coding sequences of wild‑type Sparc or preprotrypsin in SPARC‑low ST2 cells significantly reduced AP‑1 transcription activity; however, these reductions were not observed in the absence of signal peptide sequences. Recombinant SPARC, produced using Brevibacillus brevis, specifically bound to c‑Fos but not c‑Jun and inhibited the binding of c‑Fos/c‑Jun to a TPA‑response element sequence. These data suggested that SPARC was incorporated into the cells from the extracellular spaces and serves an intracellular role as a decoy counterpart for c‑Fos, as well as being associated with osteoblastogenesis through the inhibition of adipogenesis. These findings may provide new insights into regenerative medicine.

Measuring Exercise-Induced Secreted Protein Acidic and Rich in Cysteine Expression as a Molecular Tool to Optimize Personalized Medicine

The numerous exercise benefits for health as well as applications for diseases has lead to exercise being prescribed in many pathological conditions. Secreted protein acidic and rich in cysteine (SPARC) gene expression is stimulated by exercise and SPARC has been suggested as a molecular mediator of exercise. Therefore, we suggest using this property for personalized medicine. This can be achieved by prescribing the exercise with a pattern (duration, intensity, etc.) that corresponds to the optimum SPARC/Sparc expression. We expect this approach to optimize the exercise therapy in both the preventive and curative contexts. In the research field, measuring exercise -dependent expression of Sparc would represent a molecular tool to further optimize the selection of exercise animal models as well.

Secreted Protein Acidic and Rich in Cysteine as a Molecular Physiological and Pathological Biomarker

Secreted protein acidic and rich in cysteine (SPARC) is expressed in diverse tissues and plays roles in various biological functions and processes. Increased serum levels of SPARC or its gene overexpression have been reported following numerous physiological and pathological changes including injuries, exercise, regeneration, obesity, cancer, and inflammation. Such expression pattern interrelation between these biological changes and the SPARC expression/secretion points to it as a biomarker. This property could lead to a variety of potential applications ranging from mechanistic studies and animal model validation to the clinical and therapeutic evaluation of both disease prognosis and pharmacological agents.

Downregulation of secreted protein acidic and rich in cysteine in human trabecular meshwork cells

Secreted protein acidic and rich in cysteine (SPARC) may play a notable role in aqueous humor outflow through the trabecular meshwork (TM). SPARC is a potential therapeutic target in glaucoma, and the mechanism by which it regulates intraocular pressure remains unclear. The present study aimed to observe the effects of SPARC in human TM cells (HTMCs) in vitro. SPARC was downregulated by recombinant lentiviral vectors in HTMCs, and the subsequent levels of F-actin expression, zonula occludens-1 (ZO-1) expression and cellular phagocytosis were observed and calculated. It was revealed that after 48 h of culture, the expression levels of SPARC, F-actin and ZO-1 were significantly decreased in the lentivirus group compared with those in the blank control and empty vector control groups. The downregulation of SPARC promoted phagocytosis in HTMCs after 24 or 48 h of culture. This indicated that the downregulation of SPARC decreased the expression levels of the cytoskeleton-associated proteins F-actin and ZO-1, promoted phagocytosis in HTMCs and may affect the outflow of aqueous humor via the TM pathway.

Increased expression of secreted protein acidic and rich in cysteine and tissue inhibitor of metalloproteinase-3 in epidermotropic melanoma metastasis

Primary cutaneous melanoma generally arises in the epidermis, followed by invasion into the dermis. Although infrequent, invasive melanoma cells can, alternatively, migrate to the intraepidermal area and form epidermotropic melanoma metastasis (EMM). In this study, we focused on this unique manner of metastasis. To identify the key molecules which affect EMM, gene expression in EMM was compared with that in common skin metastasis (CSM). Polymerase chain reaction (PCR) analysis was performed for genes affecting the extracellular matrix, cellular adhesion, and tumor metastasis on three EMM and three CSM samples as an initial screening. For molecules showing altered expression in the EMM, expression levels were further verified using real-time quantitative PCR (qPCR) and immunohistochemistry. Five molecules showed an expression difference in the initial screening. Among these, secreted protein acidic and rich in cysteine (SPARC) was preferentially expressed in EMM (p = 0.01) by real-time qPCR. Another candidate molecule, tissue inhibitor of metalloproteinase-3 (TIMP3), was not statistically significant (p = 0.07), but showed the tendency of higher expression. These results correlated negatively to expression of N-cadherin and β-catenin. The upregulation of SPARC and TIMP3 may disrupt the continuity of the canonical Wnt pathway. This pathway regulates adhesion activity of melanoma cells to localize within the dermis, which consequently promotes EMM. Our study highlights the potential role of SPARC and TIMP3 as key molecules in EMM, and analysis of EMM may contribute for understanding melanoma invasion between the epidermis and the dermis.

SPARC inhibition accelerates NAFLD-associated hepatocellular carcinoma development by dysregulating hepatic lipid metabolism

BACKGROUND AND AIMS

Non-alcoholic fatty liver (NAFLD) and its more serious form non-alcoholic steatohepatitis increase risk of hepatocellular carcinoma (HCC). Lipid metabolic alterations and its role in HCC development remain unclear. SPARC (Secreted Protein, Acidic and Rich in Cysteine) is involved in lipid metabolism, NAFLD and diabetes, but the effects on hepatic lipid metabolism and HCC development is unknown. The aim of this study was to evaluate the role of SPARC in HCC development in the context of NAFLD.

METHODS

Primary hepatocyte cultures from knockout (SPARC^-/- ) or wild-type (SPARC^+/+ ) mice, and HepG2 cells were used to assess the effects of free fatty acids on lipid accumulation, expression of lipogenic genes and de novo triglyceride (TG) synthesis. A NAFLD-HCC model was stabilized on SPARC^-/- or SPARC^+/+ mice. Correlations among SPARC, lipid metabolism-related gene expression patterns and clinical prognosis were studied using HCC gene expression dataset.

RESULTS

SPARC^-/- mice increases hepatic lipid deposits over time. Hepatocytes from SPARC^-/- mice or inhibition of SPARC by an antisense adenovirus in HepG2 cells resulted in increased TG deposit, expression of lipid-related genes and nuclear translocation of SREBP1c. Human HCC database analysis revealed that SPARC negatively correlated with genes involved in lipid metabolism, and with poor survival. In NAFLD-HCC murine model, the absence of SPARC accelerates HCC development. RNA-seq study revealed that pathways related to lipid metabolism, cellular detoxification and proliferation were upregulated in SPARC^-/- tumour-bearing mice.

CONCLUSIONS

The absence of SPARC is associated with an altered hepatic lipid metabolism, and an accelerated NAFLD-related HCC development.

The Effect of SPARC on the Proliferation and Migration of Limbal Epithelial Stem Cells During the Corneal Epithelial Wound Healing

Secreted protein acidic and rich in cysteine (SPARC) shows a specific colocalization with limbal epithelial stem cells (LESCs) in vivo; however, the inherent relationship between SPARC and LESCs is still unclear. This study investigated the effects of SPARC on the maintenance of LESC stemness and corneal wound healing. To test the influence of different concentration of exogenous SPARC on the proliferation of LESCs, cell counting kit-8 assay and 5-ethynyl-2'-deoxyuridine staining were performed and the results indicated that 1 μg/mL SPARC was the optimum concentration for enhanced LESC proliferation. Compared with a control group, SPARC-treated group showed a higher expression of LESC-positive markers p63α, ABCG-2, and Bmi-1, and a lower level of differentiation marker cytokeratin-3 (CK3), thereby suggesting that SPARC could maintain LESC characteristic phenotype and suppress spontaneous epithelial differentiation in vitro. In vivo, exogenous SPARC accelerated the wound-healing process by both the enhancement of LESC proliferation and promoting the migration of the proliferating cells. However, the intact epithelium impaired this function of SPARC by contact inhibition.

Mechanical Consequence of Induced Intervertebral Disc Degeneration in the SPARC-Null Mouse

Intervertebral disc (IVD) degeneration is associated with low back pain (LBP) and accompanied by mechanical changes to the spine. Secreted protein acidic and rich in cysteine (SPARC) is a protein that contributes to the functioning and maintenance of the extracellular matrix. SPARC-null mice display accelerated IVD degeneration and pain-associated behaviors. This study examined if SPARC-null mice also display altered spine mechanics as compared to wild-type (WT) mice. Lumbar spines from SPARC-null (n = 36) and WT (n = 18) mice aged 14-25 months were subjected to cyclic axial tension and compression to determine neutral zone (NZ) length and stiffness. Three separate mechanical tests were completed for each spine to determine the effect of the number of IVDs tested in series (one versus two versus three IVDs). SPARC-null spine NZs were both stiffer (p < 0.001) and smaller in length (p < 0.001) than WT spines. There was an effect of the number of IVDs tested in series for NZ length but not NZ stiffness when collapsed across condition (SPARC-null and WT). Correlation analysis revealed a weak negative correlation (r = -0.24) between age and NZ length in SPARC-null mice and a weak positive correlation (r = 0.30) between age and NZ stiffness in WT mice. In conclusion, SPARC-null mice had stiffer and smaller NZs than WT mice, regardless of the number of IVDs in series being tested. The increased stiffness of these IVDs likely influences mobility at these spinal joints thereby potentially contributing to low back pain.

Secreted Protein Acidic and Rich in Cysteine as A Regeneration Factor: Beyond the Tissue Repair

Diverse pathologies (inflammation, tissues injuries, cancer, etc.) and physiological conditions (obesity, physical activity, etc.) induce the expression/secretion of the matricellular protein, secrete protein acidic and rich in cysteine (SPARC). SPARC contributes to the creation of an environment that is suitable for tissue regeneration through a variety of roles, including metabolic homeostasis, inflammation reduction, extracellular matrix remodeling and collagen maturation. Such a homeostatic environment optimizes tissue regeneration and improves tissues’ repair ability. These properties that SPARC has within the regeneration contexts could have a variety of applications, such as in obesity, cancer, sarcopenia, diabetes and bioengineering.

Expression of peritumoral SPARC during distal cholangiocarcinoma progression and correlation with outcome

Objectives: Distal cholangiocarcinoma (dCCA) is a malignancy with a dismal prognosis. One of the hallmarks is the presence of a rich desmoplastic stroma believed to contribute to tumor progression and treatment resistance. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein implicated in tumor-stroma interaction with prognostic correlation across several malignancies. The aim of the present study was to evaluate the expression pattern and prognostic significance of SPARC in resected dCCA and paired lymph node metastasis.Materials and methods: SPARC expression was evaluated in 59 resected dCCA samples and 25 paired lymph node metastases as well as 10 benign bile duct samples using immunohistochemistry. Stromal SPARC expression was scored semi quantitatively. Survival was estimated using the Kaplan-Meier method with associated log-rank test.Results: SPARC expression was absent in normal bile ducts. In dCCA, peritumoral stromal SPARC was detectable in 47/59 (80%) of samples with 40/59 (68%) classified as high stromal SPARC expression. There was a significantly lower proportion of SPARC positive stroma in paired lymph node metastasis 17/25 (68%) than the corresponding primary tumors 24/25 (96%) (p = .016). Stromal SPARC expression was associated with the presence of lymph node metastasis; high SPARC expression 31/40 (78%) versus low SPARC expression 9/19 (47%) (p = .013). In the present material there was no significant association between stromal SPARC expression and survival.Conclusions: Stromal SPARC expression occurs frequently in dCCA. Although significantly lower than in primary tumors stromal SPARC is frequently retained in paired lymph node metastasis suggesting a possible role in the metastatic process of dCCA.

SPARC Negatively Correlates With Prognosis After Transarterial Chemoembolization and Facilitates Proliferation and Metastasis of Hepatocellular Carcinoma via ERK/MMP Signaling Pathways

Background: Transarterial chemoembolization (TACE) represents a widely accepted treatment procedure for intermediate stage or unresectable hepatocellular carcinoma (HCC). However, few studies have evaluated serologic prognosis factors in patients with HCC before TACE. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein affecting tumorigenesis and metastasis, and leading to poor prognosis in HCC. Therefore, to further explore the potential prognosis value of SPARC, the expression levels in the plasma of patients and its potential molecular mechanisms underlying the regulation of HCC were investigated in this study. Materials and Methods: The study population included 43 patients with HCC who underwent TACE. To evaluate the expression of SPARC in different grades of pathological tissues, the immunohistochemistry was performed on tissues from 89 patients with HCC. Lentiviral vectors carrying interference sequences, as well as vectors harboring the complete open reading frame of SPARC for the knockdown or overexpression of SPARC in HuH-7 or HepG2 cells, respectively, allowed us to determine the biological functions of SPARC in vitro and in vivo. We also evaluated the levels of phosphorylated extracellular signal-regulated kinases 1/2 (p-ERK1/2) and matrix metalloproteinases 2/9 (MMP2/9) activation. Results: The association between serum levels of SPARC and the survival at different TNM and Barcelona-Clinic Liver Cancer (BCLC) stages in patients with HCC undergoing TACE were evaluated. We observed a significant upregulation of SPARC in high grade HCC tissues, predicting unfavorable prognosis, and suggesting an important tumor-promoting effect of SPARC. Functional studies indicated that downregulation of SPARC contributed to the inhibition of proliferation and metastasis of HuH-7 cells in vitro, whereas its overexpression led to opposite phenotypes. Mechanistically, decreased expression of SPARC resulted in dephosphorylation of ERK1/2 and deactivation of MMP2/9, thereby inhibiting growth and metastasis of HCC. Importantly, low expression levels of SPARC inhibited the formation of subcutaneous tumors in nude mice. Conclusions: SPARC was found to facilitate proliferation and metastasis of HCC via modulation of the ERK1/2-MMP2/9 signaling pathways. Our research has provided a glimpse on the biological mechanism of SPARC and might contribute to the eventual treatment of liver cancer.

The pathological complete response and secreted protein acidic and rich in cysteine expression in patients with breast cancer receiving neoadjuvant nab-paclitaxel chemotherapy

Biomarkers that can accurately predict treatment response are required for indicating optimal neoadjuvant treatments. The current study assessed the predictive value of secreted protein acidic and rich in cysteine (SPARC) mRNA expression for the response to neoadjuvant nab-paclitaxel (nab-PTX) therapy in patients with breast cancer. It was hypothesized that SPARC expression can affect the response to albumin-bound taxanes, including nab-PTX since SPARC binds albumin with a high affinity. Pre-therapeutic specimens of core needle biopsies were analyzed from 50 patients in a phase II trial of neoadjuvant nab-PTX and the factors that were associated with a pathological complete response (pCR) were assessed. The pre-therapeutic tumor mRNA levels of chemotherapy-related proteins were quantified, including SPARC, and the correlations with post-therapeutic clinicopathological factors were assessed, including with pCR. The results demonstrated that pre-therapeutic SPARC mRNA expression was significantly higher in non-pCR patients compared with patients with pCR (92.37±55.33 vs. 56.53±30.19; P=0.027). A cutoff point of 48.5 was determined using receiver operating characteristic (ROC) curve analysis (sensitivity, 83.3%; specificity, 50.0%), and patients were classified into low and high SPARC expression groups. High SPARC expression was associated with histological grade (P=0.035), estrogen receptor expression (P=0.037), and progesterone receptor expression (P=0.002) but not with HER2 (P=0.895), and Ki-67 LI (P=0.743) expression. The results of the current study indicated that a high SPARC mRNA expression was a negative predictor of pCR following neoadjuvant nab-PTX therapy regardless of breast cancer subtype. The phase II study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics Committee of the National Hospital Organization Takasaki General Medical Center (Registration nos. H23-9 and H23-33).

Accumulation of stabilin-1 positive macrophages in the early stage of gastric cancer is associated with short cumulative survival

The scavenger receptor stabilin-1 has been reported to be expressed by tumor-associated macrophages (TAMs) and to facilitate tumor growth and metastasis in mouse models of breast carcinoma and melanoma. However, to the best of our knowledge, its expression and association with prognosis in human gastric cancer has not been evaluated. The present study investigated the expression of stabilin-1 and its association with clinicopathological parameters in patients with gastric cancer. The expression of stabilin-1 was evaluated by immunohistochemical staining of gastric cancer tissue samples of 371 Chinese patients with primary gastric adenocarcinoma. Confocal laser scanning microscopy was used to determine the cellular source of stabilin-1 in the gastric cancer tissues using anti-CD68, anti-CD163, anti-stabilin-1 and anti-secreted protein acidic and rich in cysteine antibodies. A higher number of stabilin-1-positive cells were observed in the cancer tissues of primary gastric adenocarcinoma compared with adjacent non-cancerous tissues of primary gastric adenocarcinoma (P<0.001); the majority of stabilin-1-positve cells were CD68⁺/CD163⁺ macrophages. Poorly-differentiated gastric cancer tissue had fewer stabilin-1-positive cells compared with medium- and well-differentiated gastric cancer (P=0.030). A higher number of stabilin-1-positive cells were found in the early Tumor-Node-Metastasis (TNM) stage (TNM I stage) of primary gastric adenocarcinoma (P=0.038) compared with TNM stage IV. For patients with TNM stage I disease, a higher number of stabilin-1-positive TAMs was associated with shorter cumulative survival (P<0.05). Overall, stabilin-1 was found to be expressed by CD68⁺ TAMs in human gastric cancer. The high expression of stabilin-1 in TNM stage I disease was associated with poor patient survival, indicating the clinical significance of stabilin-1 in gastric cancer.

SPARC promotes self-renewal of limbal epithelial stem cells and ocular surface restoration through JNK and p38-MAPK signaling pathways

The purpose of this study was to investigate the effects of secreted protein acidic and rich in cysteine (SPARC) on the maintenance of limbal epithelial stem cell (LESC) stemness and restoration of ocular surface. To determine the suitable concentration of SPARC for LESC culture, the marker expression, mitogenic effect, and holoclone-forming capacity of LESCs treated with different concentrations of SPARC were analyzed. To investigate the mechanism of SPARC's action on the preservation of LESCs stemness, the phosphorylation of related signaling pathways was evaluated by Western blotting. A corneal wound model was established to verify the function of SPARC in ocular surface repair. Consecutive subculturing, colony-forming efficiency, immunofluorescence, and 5-ethynyl-2-deoxyuridine incorporation assays indicated that 1 μg/mL SPARC was a suitable concentration to stimulate LESC proliferation and preserve their proliferative potential. Compared with a control group, 1 μg/mL SPARC effectively increased the expression of ABCG-2, Bmi-1, and Ki67, while decreasing that of CK3/12. The mitogenic effect of SPARC on LESCs was found to be mediated by the phosphorylation of c-Jun N-terminal kinase (JNK) and p38-MAPK signaling pathways, whereas the inhibitors of JNK and p38 MAPK reduced the marker expression and mitogenic capacity of LESCs. In a corneal injury model, SPARC facilitated corneal epithelial wound healing and promoted the proliferation of p63α-positive cells both in the limbus and in the epithelial healing front. SPARC promotes proliferation while suppressing spontaneous differentiation of LESCs through JNK and p38-MAPK signaling pathways, suggesting that SPARC is a promising factor for the improvement of LESCs culture in vitro and in vivo.

The impact of SPARC expression on the survival of pancreatic ductal adenocarcinoma patients after curative resection

Background: The predictive roles of secreted protein acidic and rich in cysteine (SPARC) in pancreatic ductal adenocarcinoma (PDAC) patients after curative resection have not been clarified. We investigated the correlations between the SPARC expression and the postoperative prognosis. Methods: We retrospectively analyzed the clinical data from consecutive patients who underwent curative resection for pancreatic cancer in our institution from 2005 to 2014. Stromal SPARC expression was analyzed by immunohistochemistry on tumor tissue microarrays (TMAs) from the patients. Results: A total of 179 patients were enrolled to this study. The median follow-up period of the present study was 62.1 months. Seventy patients had positive SPARC expression (39.1%). There were no significant differences between the positive SPARC-positive group and the SPARC-negative group. In the survival analysis, there was a significant difference between the SPARC-positive and SPARC-negative groups in the 5-year overall survival (OS) rates after surgery, which were 8.1% and 19.8%, respectively (p=0.0316). A univariate analysis showed that the SPARC expression, size of tumor, lymph node metastasis, and residual tumor were possible prognostic factors. A multivariate analysis showed that the SPARC expression (hazard ratio [HR]: 1.44, 95% confidence interval [CI]: 1.017-2.051), lymph node metastasis (HR: 2.019, 95% CI: 1.318-3.091), and residual tumor (HR: 1.648, 95% CI: 1.132-2.401) were independent prognostic factors. Conclusions: The stromal SPARC expression in resectable pancreatic cancer patients might be useful as a prognostic marker.

Glucose affects cell viability, migration, angiogenesis and cellular adhesion of human retinal capillary endothelial cells via SPARC

The expression of secreted protein acidic and rich in cysteine (SPARC) has been recently identified to be associated with the pathology of diabetic retinopathy. Therefore, the present study aimed to evaluate the regulatory role of SPARC in human retinal capillary endothelial cells (HRCECs), following exposure to a high glucose environment in vitro. The cell viability, migration, angiogenesis, permeability and SPARC expression levels of HRCECs were measured following treatment with different concentrations of glucose (25, 50 or 100 mM). Lentiviral vectors (LV185-pL_shRNA_mKate2-SPARC-543; target sequence, GGATGAGGACAACAACCTTCT) that inhibit the expression of SPARC were constructed, and HRCECs were evaluated when infected by viruses carrying the lentiviral vectors. Cell viability was examined using the Cell Counting Kit-8 assay. The expression of SPARC in HRCECs increased as the concentration of glucose in the culture medium increased. Relatively high concentrations of glucose significantly inhibited cell proliferation (P<0.05), migration (P<0.05), angiogenesis (P<0.01), and the expression of ZO, occludin, claudin and JAM1 in tight junctions (P<0.01), gap junctions (Cx37 and Cx43; P<0.01) and adherens junctions (VE-cadherin, CTNNA1 and CTNNB1; P<0.05). However, when SPARC was downregulated by lentiviral vectors, the inhibitions induced by high concentrations of glucose were partially reversed. To conclude, the inhibitory effects on cell viability, migration, angiogenesis and cellular adhesion of HRCECs induced by high concentrations of glucose were reversed once the expression of SPARC was inhibited. These findings suggest that SPARC may serve an important role in pathogenesis of diabetic retinopathy.

Clinical significance of secreted protein, acidic and cysteine-rich gene expression in patients with stage II/III gastric cancer following curative resection and adjuvant chemotherapy with S-1

The standard treatment for stage II/III gastric cancer is surgical resection followed by adjuvant chemotherapy with fluoropyrimidine anticancer agents, including S-1. The protein, secreted protein, acidic and cysteine-rich (SPARC), promotes angiogenesis, and the proliferation and migration of cancer cells. The present study evaluated the significance of expression of the SPARC gene in patients with stage II/III gastric cancer who had undergone surgical resection and adjuvant chemotherapy with S-1. In the present study, reverse transcription-quantitative polymerase chain reaction was performed in order to quantify mRNA expression levels of SPARC in cancer tissues and adjacent normal mucosa obtained from 134 patients with stage II/III gastric cancer who had undergone surgical resection followed by adjuvant chemotherapy with S-1. The mRNA expression level of SPARC was significantly higher in cancer tissues than in adjacent normal mucosa (P=0.0012). Additionally, the 5-year overall survival rate was significantly poorer in patients with high SPARC gene expression than in those with low expression (P<0.0001). Furthermore, multivariate analysis indicated that high SPARC mRNA expression was a significant predictor of poorer survival in patients with stage II/III gastric cancer who had undergone surgical resection and adjuvant chemotherapy with S-1 (HR, 5.347; P<0.0001). Therefore, high expression of the SPARC gene may be a useful predictor of outcomes in patients with stage II/III gastric cancer, who have received treatment involving surgical resection and adjuvant chemotherapy with S-1.

Increased macrophage-derived SPARC precedes collagen deposition in myocardial fibrosis

Myocardial fibrosis and the resultant increases in left ventricular stiffness represent pivotal consequences of chronic pressure overload (PO) that impact both functional capacity and the rates of morbid and mortal events. However, the time course and cellular mechanisms that underlie PO-induced fibrosis have not been completely defined. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that has been shown to be required for insoluble collagen deposition and increased myocardial stiffness in response to PO in mice. As macrophages are associated with increases in fibrillar collagen, the hypothesis that macrophages represent a source of increased SPARC production in the PO myocardium was tested. The time course of changes in the myocardial macrophage population was compared with changes in procollagen type I mRNA, production of SPARC, fibrillar collagen accumulation, and diastolic stiffness. In PO hearts, mRNA encoding collagen type I was increased at 3 days, whereas increases in levels of total collagen protein did not occur until 1 wk and were followed by increases in insoluble collagen at 2 wk. Increases in muscle stiffness were not detected before increases in insoluble collagen content (>1 wk). Significant increases in myocardial macrophages that coincided with increased SPARC were found but did not coincide with increases in mRNA encoding collagen type I. Furthermore, immunohistochemistry and flow cytometry identified macrophages as a cellular source of SPARC. We conclude that myocardial macrophages play an important role in the time-dependent increases in SPARC that enhance postsynthetic collagen processing, insoluble collagen content, and myocardial stiffness and contribute to the development of fibrosis. NEW & NOTEWORTHY Myocardial fibrosis and the resultant increases in left ventricular and myocardial stiffness represent pivotal consequences of chronic pressure overload. In this study a murine model of cardiac fibrosis induced by pressure overload was used to establish a time course of collagen expression, collagen deposition, and cardiac macrophage expansion.

MicroRNA-211 suppresses prostate cancer proliferation by targeting SPARC

Dysregulation of microRNAs (miRNAs/miRs) is frequently associated with cancer progression. Altered expression of miR-211 has been observed in various types of human cancer; however, its expression and role in prostate cancer (PCa) remains unknown. In the present study, the expression of miR-211 in PCa cell lines and tissues was measured by reverse transcription-quantitative PCR (qPCR), revealing that miR-211 was downregulated in PCa cell lines and tissues. Further analysis revealed that low miR-211 was associated with the tumor stage and Gleason score. With the assistance of miR-211 mimics and inhibitor, it was also revealed that the overexpression of miR-211 could inhibit PCa cell proliferation in vitro. Conversely, downregulated miR-211 expression promotes PCa cell proliferation. In addition, the secreted protein acidic and rich in cysteine (SPARC) was identified as a target of miR-211 in the PCa cell lines, and SPARC expression was inversely associated with miR-211. In conclusion, it was demonstrated that the miR-211 expression was downregulated in PCa cell lines and tissues. Additionally, miR-211 could inhibit PCa cell proliferation partially by downregulating SPARC. Therefore, miR-211 may be a potential therapeutic target for PCa treatment in the future.

The prognostic significance of cancer-associated fibroblasts in pancreatic ductal adenocarcinoma

Cancer-associated fibroblasts are abundant in the desmoplastic stroma of pancreatic ductal adenocarcinomas and are considered to play important roles in tumor progression. In this study, we investigated the expression status of secreted protein acidic and rich in cysteine, periostin, fibroblast-activated protein, and the newly developed proCOL11A1 antibody in the stroma of surgically resected pancreatic ductal adenocarcinomas and their prognostic implications. Tissue microarrays were constructed from 155 surgically resected pancreatic ductal adenocarcinomas and paired non-neoplastic pancreata and from another independent set of 48 normal/benign pancreata, and immunohistochemical stains were performed for proCOL11A1, fibroblast-activated protein, secreted protein acidic and rich in cysteine, and periostin. The immunohistochemical stain results were correlated with clinicopathological features and survival data. proCOL11A1, fibroblast-activated protein, secreted protein acidic and rich in cysteine, and periostin expression was significantly increased in the intratumoral stroma of pancreatic ductal adenocarcinomas compared to paired non-neoplastic pancreata (proCOL11A1: 145/155 (93.5%) vs 26/154 (16.9%); fibroblast-activated protein: 139/143 (97.2%) vs 82/132 (62.1%); secreted protein acidic and rich in cysteine: 113/150 (75.3%) vs 49/132 (37.1%); periostin: 135/151 (89.4%) vs 45/135 (33.3%); p < 0.001, all). While the four markers were expressed at lower levels in normal/benign pancreata, there were no significant differences in the expression frequencies among normal pancreas, acute pancreatitis, and chronic pancreatitis. Interestingly, on survival analysis, low intratumoral fibroblast-activated protein⁺ cancer-associated fibroblast counts (<100/high-power field) were associated with a significantly reduced overall survival compared to those with high fibroblast-activated protein⁺ cancer-associated fibroblast counts (p = 0.010; hazard ratio 5.2 (95% confidence interval 1.3-21.3)). Similar patterns were seen for proCOL11A and secreted protein acidic and rich in cysteine and overall and disease-free survival, although not statistically significant. In conclusion, we demonstrate that the presence of cancer-associated fibroblasts in the tumor stroma may not always be associated with a poor prognosis as suggested in many studies; on the contrary, it may even be associated with prolonged survival, supporting the recent experimental findings that tumor stroma may have a protective role rather than enhance aggressive behavior.

SPARC inhibits breast cancer bone metastasis and may be a clinical therapeutic target

Breast cancer is one of the most common types of cancer in females worldwide, and metastasis to bone is an important characteristic of malignancy. The present study aimed to investigate the molecular mechanism of breast cancer to bone metastasis of secreted protein acidic and rich in cysteine (SPARC). Immunohistochemistry was performed to examine the expression of SPARC in primary breast tumors and bone metastatic foci. Western blotting and reverse transcription-quantitative polymerase chain reaction were performed to detect the expression level of SPARC in several types of breast cancer cell. A Transwell filter assay was used to assess the effect of SPARC on breast cancer cell invasion ability, and an osteoblast differentiation assay was employed to analyze the effect of SPARC on the differentiation ability of mesenchymal stem cells. Clinical data revealed that decreased stromal SPARC expression is associated with breast cancer to bone metastasis. Gain- and loss-of-function studies reveal that SPARC inhibits the migration and invasion of breast cancer cells, and suppresses osteoclast activation in the breast cancer microenvironment. SPARC serves an important role in breast cancer bone metastasis and may be a promising therapeutic target for the treatment of breast cancer bone metastasis.

Expression and significance of secreted protein acidic and rich in cysteine in human osteosarcoma

Osteosarcoma is the most common primary malignancy of bone, and is a high-grade malignant mesenchymal tumor with high recurrence and metastatic rates. Increased expression of secreted protein, acidic and rich in cysteine (SPARC) indicates poor prognosis in a number of malignances. However, the expression level of SPARC in human osteosarcoma and its associated mechanism remains unclear. To analyze the expression of SPARC in human osteosarcoma and its potential application in the diagnosis and treatment of osteosarcoma, the clinical records and samples of 20 cases of osteosarcoma were collected. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis applied to detect SPARC expression levels in osteosarcoma tissues, with normal bone tissue as control. Immunofluorescence detection was used to examine the distribution of SPARC. The association between SPARC level and clinical factors was analyzed. RT-qPCR (P=0.002) indicated that the SPARC level in osteosarcoma tissues was significantly increased compared with that in normal tissues. Immunofluorescence detection indicated that SPARC was widely distributed in tumor tissues. SPARC protein expression level was positively associated with lung metastasis (P=0.016). The results indicated that SPARC tends to be highly expressed in human osteosarcoma tissues. The expression level of SPARC is associated with lung metastasis, which may be an indicator of prognosis. Thus, SPARC may be a potential tumor marker and therapeutic target in osteosarcoma.

Secreted Protein Acidic and Rich in Cysteine (SPARC) Enhances Cell Proliferation, Migration, and Epithelial Mesenchymal Transition, and SPARC Expression is Associated with Tumor Grade in Head and Neck Cancer

Secreted protein acidic and rich in cysteine (SPARC) is a secreted protein which is involved in various biological processes. SPARC expression is associated with tumor metastasis and poor prognosis in several types of cancer. However, the SPARC-induced signaling pathway was not fully understood in head and neck cancer. In this study, our results showed that SPARC treatment promoted cell proliferation and migration in head and neck cancer cell lines FaDu and Detroit 562. In addition, SPARC induced expression of epithelial mesenchymal transition (EMT) regulators, including Slug, Snail, and Twist in Detroit 562. The results of phospho-kinase array analysis showed that SPARC treatment increased phosphorylation of some molecules including protein kinase B (PKB/AKT), ribosomal S6 kinase (RSK), and extracellular signal–regulated kinases (ERK). The expression of SPARC-induced EMT regulator Slug was suppressed by AKT inhibitor, but not ERK and RSK inhibitors. The SPARC expression in grade IV tumor samples is higher when compared to that in grade I–III tumor samples. Our results suggest that SPARC treatment enhances the EMT signaling pathway via activation of AKT, and exogenous SPARC and tumor expressing SPARC might be associated with tumor progression in head and neck cancers.

Clinicopathological and immunohistochemical features of lung invasive mucinous adenocarcinoma based on computed tomography findings

Background

We performed an analysis to clarify differences in clinicopathological and molecular features of lung invasive mucinous adenocarcinoma (IMA) based on computed tomography (CT) findings and their impact on prognosis.

Patients and methods

On the basis of CT findings, we divided lung IMA into three subtypes: solid, bubbling, and pneumonic. We then investigated differences in clinicopathological characteristics, prognosis, and the expressions of well-identified biomarkers, including cyclooxygenase-2 (Cox-2), excision repair cross-complementation group 1 (ERCC1), ribonucleotide reductase M1 (RRM1), class III beta-tubulin, thymidylate synthase (TS), secreted protein acidic and rich in cysteine (SPARC), programmed cell death-1 ligand-1 (PD-L1), and epidermal growth factor receptor mutation, among the three subtypes.

Results

A total of 29 patients with resected lung IMA were analyzed. Compared with the solid or bubbling type, the pneumonic type had a higher proportion of symptoms, a larger tumor size, a higher pathological stage, and a significantly worse prognosis. The immunohistochemical findings tended to show high expression of RRM1, class III beta-tubulin, and Cox-2 in the tumor and of SPARC in the stroma, but not of ERCC1, TS, and PD-L1 in the tumor. None of the biomarkers with high expression levels in the tumor were prognostic biomarkers, but the expression of SPARC in the stroma was correlated with a poor outcome.

Conclusion

Clinical and pathological features, in conjunction with molecular data, indicate that IMA should be divided into different subgroups. In our results, the pneumonic type was correlated with a significantly worse outcome. Further studies should be performed to confirm our conclusion and to explore its molecular implications.

Increased ADAMTS1 mediates SPARC-dependent collagen deposition in the aging myocardium

Secreted protein acidic and rich in cysteine (SPARC) is a collagen-binding matricellular protein highly expressed during fibrosis. Fibrosis is a prominent component of cardiac aging that reduces myocardial elasticity. Previously, we reported that SPARC deletion attenuated myocardial stiffness and collagen deposition in aged mice. To investigate the mechanisms by which SPARC promotes age-related cardiac fibrosis, we evaluated six groups of mice (n = 5-6/group): young (3-5 mo old), middle-aged (10-12 mo old), and old (18-29 mo old) C57BL/6 wild type (WT) and SPARC-null (Null) mice. Collagen content, determined by picrosirius red staining, increased in an age-dependent manner in WT but not in Null mice. A disintegrin and metalloproteinase with thrombospondin-like motifs 1 (ADAMTS1) increased in middle-aged and old WT compared with young, whereas in Null mice only old animals showed increased ADAMTS1 expression. Versican, a substrate of ADAMTS1, decreased with age only in WT. To assess the mechanisms of SPARC-induced collagen deposition, we stimulated cardiac fibroblasts with SPARC. SPARC treatment increased secretion of collagen I and ADAMTS1 (both the 110-kDa latent and 87-kDa active forms) into the conditioned media as well as the cellular expression of transforming growth factor-β1-induced protein (Tgfbi) and phosphorylated Smad2. An ADAMTS1 blocking antibody suppressed the SPARC-induced collagen I secretion, indicating that SPARC promoted collagen production directly through ADAMTS1 interaction. In conclusion, ADAMTS1 is an important mediator of SPARC-regulated cardiac aging.

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.

Association of serum SPARC level with severity of coronary artery lesion in type 2 diabetic patients with coronary heart disease

OBJECTIVE

To investigate the association of serum SPARC level with the severity of coronary artery lesion in type 2 diabetic patients with coronary heart disease.

METHODS

120 patients with type 2 diabetic patients were the subjects. Enzyme-linked immunosorbent assay (ELISA) was used to detect levels of serum SPARC and Gensini score was used to assess extent of coronary artery lesions. The patients were divided into 4 groups: A group was the healthy control group with 40 patients. According to angiography and the World Health Organization (WHO) diagnostic criteria for diabetes the rest were divided into B, C, D group: there were 40 cases in group B (simple type 2 diabetes mellitus group), 40 cases were in group C (simple CHD group), and 40 cases were in D group (type 2 diabetes combined with coronary heart disease group).

RESULTS

Compared with that in group A, the serum SPARC level in group B, C and D increased significantly (4.22±1.19) μg/L, (3.71±1.05) μg/L and (5.96±1.40) μg/L vs (3.60±0.40) μg/L (P<0.05 ). Moreover, the serum SPARC level in group D was the highest (P<0.05). Serum SPARC level, insulin resistance (IR), and glycosylated hemoglobin (HbA1c) were the vital factors contributing to coronary heart disease. Serum SPARC level was positively correlated with the Gensini scores in group D (r=0.770, P<0.05), whereas it was not related to the Gensini scores in group C (r=0.520, P>0.05). Pearson correlation analysis showed that serum SPARC level was positively correlated with triglyceride, fasting insulin, Homeostasis Model Assessment for Insulin Resistance Index (r=0.780, 0.762 and 0.891, respectively; P<0.05).

CONCLUSION

Serum SPARC level elevated in T2DM patients with coronary heart disease, which was correlated with the severity of coronary artery disease significantly.

Secreted protein acidic and rich in cysteine facilitates age-related cardiac inflammation and macrophage M1 polarization

To investigate the role of secreted protein acidic and rich in cysteine (SPARC) in age-related cardiac inflammation, we studied six groups of mice: young (3-5 mo old), middle-aged (10-12 mo old), and old (18-29 mo old) C57BL/6 wild-type (WT) and SPARC-null (Null) mice (n = 7-10/group). Cardiac function and structure were determined by echocardiography. The left ventricle was used for cytokine gene array and macrophage quantification by immunohistochemistry. Macrophage infiltration increased with age in WT (n = 5-6/group, P < 0.05 for young vs. old), but not in Null. Proinflammatory markers (Ccl5, Cx3cl1, Ccr2, and Cxcr3) increased in middle-aged and old WT, whereas they were increased only in old Null compared with respective young (n = 5-6/group, P < 0.05 for all). These results suggest that SPARC deletion delayed age-related cardiac inflammation. To further assess how SPARC affects inflammation, we stimulated peritoneal macrophages with SPARC (n = 4). SPARC treatment increased expression of proinflammatory macrophage M1 markers and decreased anti-inflammatory M2 markers. Echocardiography (n = 7-10/group) revealed an age-related increase in wall thickness of the left ventricle in WT (0.76 ± 0.02 mm in young vs. 0.91 ± 0.03 mm in old; P < 0.05) but not in Null (0.78 ± 0.01 mm in young vs. 0.84 ± 0.02 mm in old). In conclusion, SPARC deletion delayed age-related increases in macrophage infiltration and proinflammatory cytokine expression in vivo and in vitro. SPARC acts as an important mediator of age-related cardiac inflammation by increasing the expression of macrophage M1 markers and decreasing M2 markers.

Prognostic role of SPARC expression in gastric cancer: a meta-analysis

INTRODUCTION

Secreted protein acidic and rich in cysteine (SPARC) is involved in regulating cell adhesion, proliferation, migration, and tissue remodeling. We performed a meta-analysis to evaluate the association between SPARC expression and the clinicopathologic features and outcomes of gastric cancer patients.

MATERIAL AND METHODS

Publications that assessed the clinical or prognostic significance of SPARC in gastric cancer up to October 2013 were identified. A meta-analysis was performed to clarify the association between SPARC expression and clinical outcomes.

RESULTS

Ten studies, including 1417 cases, met the inclusion criteria. The data were analyzed and the results show that SPARC is not significantly associated with the depth of gastric cancer invasion (odds ratio (OR) = 1.17, 95% confidence interval (CI): 0.60-2.29, Z = 0.47, p = 0.64) or tumor differentiation (OR = 0.59, 95% CI: 0.22-1.58, Z = 1.06, p = 0.29). Moreover, SPARC was not significantly correlated with lymph node metastasis (OR = 0.72, 95% CI: 0.37-1.41, Z = 0.96, p = 0.34). However, SPARC overexpression was highly correlated with reduced overall survival (relative risk (RR) = 1.78, 95% CI: 1.52-2.09, Z = 7.10, p = 0.43).

CONCLUSIONS

The SPARC may play an important role in the progression of gastric cancer, and SPARC overexpression is closely correlated with poor patient survival. The SPARC is a potential clinical marker for the survival of gastric cancer patients; however, well-designed prospective studies are needed to confirm these findings.

Secreted protein acidic and rich in cysteine internalization and its age-related alterations in skeletal muscle progenitor cells

Aging causes phenotypic changes in skeletal muscle progenitor cells (Skm-PCs), such as reduced myogenesis and increased adipogenesis due to alterations in their environment or niche. Secreted protein acidic and rich in cysteine (SPARC), which is secreted into the niche of Skm-PCs, inhibits adipogenesis and promotes myogenesis. We have previously reported that Skm-PC responsiveness to SPARC declines with age, although the mechanism underlying this decline is unknown. In this study, we found that SPARC is internalized by Skm-PCs and that this uptake increases with age. Internalization is dependent on integrin-α5, a cell surface SPARC-binding molecule, and clathrin-mediated endocytosis. We also demonstrated that internalized SPARC is transported to Rab7-positive endosomes. Skm-PCs from old rats exhibited increased clathrin expression and decreased Rab7 expression exclusively in MyoD-negative cells. In loss-of-function analyses, clathrin knockdown increased the anti-adipogenic effect of SPARC, whereas Rab7 knockdown reduced it, indicating that alterations in SPARC internalization may mediate the age-related decline in its anti-adipogenic effect. These results provide insights into age-related SPARC resistance in Skm-PCs, which may lead to sarcopenia.

Electroconvulsive seizure induces thrombospondin-1 in the adult rat hippocampus

Synaptic dysfunction has recently gained attention for its involvement in mood disorders. Electroconvulsive therapy (ECT) possibly plays a role in synaptic repair. However, the underlying mechanisms remain uncertain. Thrombospondin-1 (TSP-1), a member of the TSP family, is reported to be secreted by astrocytes and to regulate synaptogenesis. We investigated the effects of electroconvulsive seizure (ECS) on the expression of TSPs in the adult rat hippocampus. Single and repeated ECS significantly increased TSP-1 mRNA expression after 2h and returned to sham levels at 24h. Conversely, the TSP-2 and -4 mRNA levels did not change. Only repeated ECS induced TSP-1 proteins. ECS also induced glial fibrillary acidic protein (GFAP) expression. The GFAP expression occurred later than the TSP-1 mRNA expression following single ECS; however, it occurred earlier and was more persistent following repeated ECS. ECS had no effect on the α2δ-1 or neuroligin-1 expressions, both of which are TSP-1 receptors. Furthermore, chronic treatment with antidepressants did not induce the expression of TSP-1 or GFAP. These findings suggest that repeated ECS, but not chronic treatment with antidepressants, induces TSP-1 expression partially via the activation of astrocytes. Therefore, TSP-1 is possibly involved in the synaptogenic effects of ECS.

The stromal compartments in pancreatic cancer: are there any therapeutic targets?

Pancreatic ductal adenocarcinoma (PDAC) is characterised by an abundant stromal response also known as a desmoplastic reaction. Pancreatic Stellate Cells have been identified as playing a key role in pancreatic cancer desmoplasia. There is accumulating evidence that the stroma contributes to tumour progression and to the low therapeutic response of PDAC patients. In this review we described the main actors of the desmoplastic reaction within PDAC and novel therapeutic approaches that are being tested to block the detrimental function of the stroma.

The potential neuroprotective effect of human adipose stem cells conditioned medium against light-induced retinal damage

Human adipose-derived stem cells (hASCs) are present in adult adipose tissue and have been reported to secrete various factors that have neuroprotective effects. In the present study, we examined whether hASC-conditioned medium (hASC-CM) was effective against experimental degenerative retinal disease. Mature adipocytes (MAs) and hASCs were isolated from human subcutaneous adipose tissue. The isolated hASCs were identified based on their capacity for bone and neural differentiation. The effects of hASC-CM against tunicamycin-, H2O2-, and light-induced retinal photoreceptor damage were evaluated in vitro by measuring cell death. Moreover, we identified various factors present in hASC-CM using antibody arrays. Retinal damage induced in mice by exposure to white light was studied in vivo, and photoreceptor damage was evaluated according to the thickness of the outer nuclear layer and electroretinography results. In addition, the effect of hASC-CM on Akt phosphorylation at Ser473 was confirmed by western blotting. Finally, the effects of the secreted proteins identified in the hASC-CM on light-induced damage were evaluated in vivo. Isolated hASCs differentiated to osteocytes and neurons. hASC-CM protected against tunicamycin-, H2O2-, and light-induced cell death. In addition, hASC-CM inhibited photoreceptor degeneration and retinal dysfunction after exposure to light. Several proteins secreted by hASCs, such as the tissue inhibitor of metalloproteinase-1 (TIMP-1) and the secreted protein acidic and rich in cysteine (SPARC), protected against light-induced damage in vitro and in vivo. The results of the present study showed that hASC-CM has neuroprotective effects against light-induced retinal damage and suggest that hASCs have a therapeutic potential in retinal degenerative diseases via their secreted proteins, without requiring transplantation.

Age-dependent alterations in fibrillar collagen content and myocardial diastolic function: role of SPARC in post-synthetic procollagen processing

Advanced age, independent of concurrent cardiovascular disease, can be associated with increased extracellular matrix (ECM) fibrillar collagen content and abnormal diastolic function. However, the mechanisms causing this left ventricular (LV) remodeling remain incompletely defined. We hypothesized that one determinant of age-dependent remodeling is a change in the extent to which newly synthesized procollagen is processed into mature collagen fibrils. We further hypothesized that secreted protein acidic and rich in cysteine (SPARC) plays a key role in the changes in post-synthetic procollagen processing that occur in the aged myocardium. Young (3 mo old) and old (18-24 mo old) wild-type (WT) and SPARC-null mice were studied. LV collagen content was measured histologically by collagen volume fraction, collagen composition was measured by hydroxyproline assay as soluble collagen (1 M NaCl extractable) versus insoluble collagen (mature cross-linked), and collagen morphological structure was examined by scanning electron microscopy. SPARC expression was measured by immunoblot analysis. LV and myocardial structure and function were assessed using echocardiographic and papillary muscle experiments. In WT mice, advanced age increased SPARC expression, myocardial diastolic stiffness, fibrillar collagen content, and insoluble collagen. In SPARC-null mice, advanced age also increased myocardial diastolic stiffness, fibrillar collagen content, and insoluble collagen but significantly less than those seen in WT old mice. As a result, insoluble collagen and myocardial diastolic stiffness were lower in old SPARC-null mice (1.36 +/- 0.08 mg hydroxyproline/g dry wt and 0.04 +/- 0.005) than in old WT mice (1.70 +/- 0.10 mg hydroxyproline/g dry wt and 0.07 +/- 0.005, P < 0.05). In conclusion, the absence of SPARC reduced age-dependent alterations in ECM fibrillar collagen and diastolic function. These data support the hypothesis that SPARC plays a key role in post-synthetic procollagen processing and contributes to the increase in collagen content found in the aged myocardium.