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SPARC Expression (sparc + expression)

Distribution by Scientific Domains

Medical Sciences	71%

Selected Abstracts

Frequent inactivation of SPARC by promoter hypermethylation in colon cancers

INTERNATIONAL JOURNAL OF CANCER, Issue 3 2007
Eungi Yang
Abstract Epigenetic modification of gene expression plays an important role in the development of human cancers. The inactivation of SPARC through CpG island methylation was studied in colon cancers using oligonucleotide microarray analysis and methylation specific PCR (MSP). Gene expression of 7 colon cancer cell lines was evaluated before and after treatment with the demethylating agent 5-aza-2,-deoxycytidine (5Aza-dC) by oligonucleotide microarray analysis. Expression of SPARC was further examined in colon cancer cell lines and primary colorectal cancers, and the methylation status of the SPARC promoter was determined by MSP. SPARC expression was undetectable in 5 of 7 (71%) colorectal cancer cell lines. Induction of SPARC was demonstrated after treatment with the demethylating agent 5Aza-dC in 5 of the 7 cell lines. We examined the methylation status of the CpG island of SPARC in 7 colon cancer cell lines and in 20 test set of colon cancer tissues. MSP demonstrated hypermethylation of the CpG island of SPARC in 6 of 7 cell lines and in all 20 primary colon cancers, when compared with only 3 of 20 normal colon mucosa. Immunohistochemical analysis showed that SPARC expression was downregulated or absent in 17 of 20 colon cancers. A survival analysis of 292 validation set of colorectal carcinoma patients revealed a poorer prognosis for patients lacking SPARC expression than for patients with normal SPARC expression (56.79% vs. 75.83% 5-year survival rate, p = 0.0014). The results indicate that epigenetic gene silencing of SPARC is frequent in colon cancers, and that inactivation of SPARC is related to rapid progression of colon cancers. © 2007 Wiley-Liss, Inc. [source]

Proteomic analysis identified N-cadherin, clusterin, and HSP27 as mediators of SPARC (secreted protein, acidic and rich in cysteines) activity in melanoma cells

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 22 2007
María Soledad Sosa
Abstract Secreted protein, acidic and rich in cysteines (SPARC) is a secreted protein associated with increased aggressiveness of different human cancer types. In order to identify downstream mediators of SPARC activity, we performed a 2-DE proteomic analysis of human melanoma cells following antisense-mediated downregulation of SPARC expression. We found 23/504 differential spots, 15 of which were identified by peptide fingerprinting analysis. Three of the differential proteins (N-cadherin (N-CAD), clusterin (CLU), and HSP27) were validated by immunoblotting, confirming decreased levels of N-CAD and CLU and increased amounts of HSP27 in conditioned media of cells with diminished SPARC expression. Furthermore, transient knock down of SPARC expression in melanoma cells following adenoviral-mediated transfer of antisense RNA confirmed these changes. We next developed two different RNAs against SPARC that were able to inhibit in vivo melanoma cell growth. Immunoblotting of the secreted fraction of RNAi-transfected melanoma cells confirmed that downregulation of SPARC expression promoted decreased levels of N-CAD and CLU and increased secretion of HSP27. Transient re-expression of SPARC in SPARC-downregulated cells reverted extracellular N-CAD, CLU, and HSP27 to levels similar to those in the control. These results constitute the first evidence that SPARC, N-CAD, CLU, and HSP27 converge in a unique molecular network in melanoma cells. [source]

SPARC (Osteonectin) in Breast Tumors of Different Histologic Types and Its Role in the Outcome of Invasive Ductal Carcinoma

THE BREAST JOURNAL, Issue 3 2010
Yi-Hsuan Hsiao MD
Abstract:, The purpose of this study was to characterize the immunohistochemical distribution of secreted protein acidic and rich in cystein (SPARC) in benign and malignant breast tumors of different histologic types and define its association with the outcome of invasive ductal carcinoma (IDC) patients. A total of 286 samples of benign and malignant breast lesions between 1994 and 2005 were retrieved from National Taiwan University Hospital. Up to 11 years clinical follow-up data were available for 185 patients with IDC. Immunohistochemistry staining with SPARC was performed in tissue microarray or whole section. The association of expression of SPARC and cumulative overall survival of IDC patients were analyzed using Kaplan,Meier survival analysis and Cox regression analysis. Secreted protein acidic and rich in cystein was not expressed in benign breast phylloides and all benign breast tumors, while expressed in 17.2% of IDC, 85% of metaplastic carcinoma of the breast (MCB), and all malignant breast phylloides. Secreted protein acidic and rich in cystein was strongly expressed in mesenchymal components of MCB and expression levels in epithelial components were variable. The correlation of positive expression of SPARC and poor long-term survival in IDC is significant (p = 0.004). Individuals with positive SPARC expression had 2.34 times higher hazard of death compared with those with negative SPARC expression after adjusting for factors including positive lymph node, TNM tumor stage, estrogen receptor, and progesterone receptor. Secreted protein acidic and rich in cystein may be useful as a prognostic indicator for IDC. [source]

Immunohistochemical expression of SPARC is correlated with recurrence, survival and malignant potential in meningiomas

APMIS, Issue 9 2009
SUHEYLA UYAR BOZKURT
Meningioma is a common neoplasm that constitutes almost 30% of all primary central nervous system tumors and is associated with inconsistent clinical outcomes. The extracellular matrix proteins play a crucial role in meningioma cell biology and are important in tumor cell invasion and in progression to malignancy. SPARC (secreted protein, acidic and rich in cysteine) (osteonectin) is a matricellular glycoprotein that regulates cell function by interacting with different extracellular matrix proteins. The aim of this study was to evaluate the expression of SPARC with proliferation index, p53 reactivity in WHO grade 1 (benign), grade 2 (atypical) and grade 3 (anaplastic) meningiomas and correlate with clinical features of the patients, including location of the tumor, recurrence of the tumor and survival of patients. We studied 111 meningiomas, 69 being benign, 34 being atypical and eight being anaplastic meningiomas of various histological types. Using immunohistochemical analysis, we evaluated the expression of SPARC, Ki-67 (MIB-1) and p53 in meningiomas. Immunohistochemical scores of SPARC were determined as the sum of frequency (0,3) and intensity (0,3) of immunolabeling of the tumor cells. A high immunohistochemical score (4,6) for SPARC was more frequent in atypical and in anaplastic meningiomas than in benign meningiomas (p < 0.01). MIB-1 proliferation index showed significant association between tumor grades in meningiomas (p < 0.01). At the end of a follow-up period of 47.53 ± 25.04 months, 30 tumors recurred. A high SPARC expression was significantly associated with tumor recurrence (p = 0.02). The immunoreactivity of p53 protein and MIB-1 score were significantly higher in recurrent meningiomas than in non-recurrent meningiomas. The cumulative survival of patients with high SPARC expression was significantly lower than patients with low SPARC expression. The high SPARC expression scores were predominantly identified in meningothelial, fibrous and chordoid meningiomas; low SPARC expression scores were mostly spotted in secretory and psammomatous meningiomas. Evaluating SPARC expression might help assessing recurrence risk and survival estimation in meningiomas. [source]