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Open Access Research article

Overexpression of sphingosine kinase 1 is associated with salivary gland carcinoma progression and might be a novel predictive marker for adjuvant therapy

Guanglin Liu1, Haiqing Zheng2, Zhibing Zhang1, Zhiqiang Wu3, Huaping Xiong4, Jun Li3 and Libing Song1*

Author Affiliations

1 State Key Laboratory of Oncology in Southern China, Department of Experimental Research, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong, China

2 Department of Rehabilitation Medicine, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China

3 Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China

4 Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China

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BMC Cancer 2010, 10:495  doi:10.1186/1471-2407-10-495

Published: 16 September 2010

Abstract

Background

Overexpression of sphingosine kinase-1 (SPHK1) has been demonstrated to be associated with the development and progression in various types of human cancers. The current study was to characterize the expression of SPHK1 in salivary gland carcinomas (SGC) and to investigate the association between SPHK1 expression and progression of SGC.

Methods

The expression of SPHK1 was examined in 2 normal salivary gland tissues, 8 SGC tissues of various clinical stages, and 5 pairs of primary SGC and adjacent salivary gland tissues from the same patient, using real-time PCR and western blot analysis. Furthermore, the SPHK1 protein expression was analyzed in 159 clinicopathologically characterized SGC cases by immunohistochemistry. Statistical analyses were performed to determine the prognostic and diagnostic associations.

Results

SPHK1 expression was found to be markedly upregulated in SGC tissues than that in the normal salivary gland tissues and paired adjacent salivary gland tissues, at both mRNA and protein levels. Statistical analysis revealed a significant correlation of SPHK1 expression with the clinical stage (P = 0.005), T classification (P = 0.017), N classification (P = 0.009), M classification (P = 0.002), and pathological differentiation (P = 0.013). Patients with higher SPHK1 expression had shorter overall survival time, whereas patients with lower SPHK1 expression had better survival. Importantly, patients in the group without adjuvant therapy who exhibited high SPHK1 expression had significantly lower overall survival rates compared with those with low SPHK1 expression. Moreover, multivariate analysis suggested that SPHK1 expression might be an independent prognostic indicator for the survival of SGC patients.

Conclusions

Our results suggest that SPHK1 expression is associated with SGC progression, and might represent as a novel and valuable predictor for adjuvant therapy to SGC patients.