Secreted protein acidic and rich in cysteine (SPARC) is associated with nasopharyngeal carcinoma metastasis and poor pro
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RESEARCH
Open Access
Secreted protein acidic and rich in cysteine (SPARC) is associated with nasopharyngeal carcinoma metastasis and poor prognosis Hai-Yun Wang1,2†, Yang-Yang Li1,2†, Qiong Shao2, Jing-Hui Hou3, Fang Wang1,2, Man-Bo Cai1,4, Yi-Xin Zeng1,4 and Jian-Yong Shao1,2,4*
Abstract Background: The aim of the present study was to analyse the expression of Secreted protein acidic and rich in cysteine (SPARC) in nasopharyngeal carcinoma (NPC) specimens, and to evaluate its correlation with clinicopathologic features, including survival of patients with NPC Methods: NPC tissue microarrays (TMAs) were constructed from Sun Yat-sen University Cancer Center (SYSUCC), another three centers on mainland China, Singapore and Hong Kong. Using quantitative RT-PCR and Westernblotting techniques, we detected mRNA and protein expression of SPARC in NPC cell lines and immortalized nasopharyngeal epithelial cells (NPECs) induced by Bmi-1 (NPEC2 Bmi-1). The difference of SPARC expression in the cell lines was tested using a t-test method. The relationship between the SPARC expression and clinicopathological data was assessed by chi-square. Survival analysis was estimated using the Kaplan-Meier approach with log-rank test. Univariate and multivariate analyses of clinical variables were performed using Cox proportional hazards regression models. Results: The expression levels of SPARC mRNA and protein were markedly higher in NPC cell lines than in NPEC2 Bmi-1. Especially, the expression levels of SPARC mRNA and protein were much lower in the 6-10B than in the 5-8 F (P = 0.002, P = 0.001). SPARC immunostaining revealed cytoplasmic localization in NPC cells and no staining in the stroma and epithelium. In addition, high level of SPARC positively correlated with the status of distant metastasis (P = 0.001) and WHO histological classification (P = 0.023). NPC patients with high SPARC expression also had a significantly poorer prognosis than patients with low SPARC expression (log-rank test, P < 0.001), especially patients with advanced stage disease (log-rank, P < 0.001). Multivariate analysis suggested that the level of SPARC expression was an independent prognostic indicator for the overall survival of patients with NPC (P < 0.001). Conclusions: SPARC expression is common in NPC patients. Our data shows that elevated SPARC expression is a potential unfavorable prognostic factor for patients with NPC. Keywords: SPARC, Nasopharyngeal carcinoma, Metastasis
* Correspondence: [email protected] † Contributed equally 1 State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou 510060, People’s Republic of China Full list of author information is available at the end of the article © 2012 Wang et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the ori
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