The impact of sphingosine kinase 1 on the prognosis of hepatocellular carcinoma patients with portal vein tumor thrombus

Background. Though there is considerable evidence that sphingosine kinase 1(SPHK1) plays a key role in hepatocellular carcinoma(HCC) progression, the prognostic value of SPHK1 expression in HCC with portal vein tumor thrombus (PVTT) remains unclear. Aims. The purpose of this study was to investigate the relationship of SPHK1 expression with PVTT and HCC recurrence after hepatectomy. Methods. After screening of gene expression profiling of tumor cell lines, real-time PCR and immunohistochemistry were used to investigate the SPHK1 expression in PVTT and HCC samples. The clinical data of 199 HCC patients with nonmain PVTT who underwent liver resection with curative intention were studied. Results. We identified SPHK1 as the most over-expressed gene in PVTT via gene expression profiling of one human PVTT cell line (CSQT-2). SPHK1 expression was an independent factor affecting survival (hazard ratio [HR] 1.799, 95% confidence interval [CI] 1.337–2.368, P < 0.001) and tumor recurrence (HR 1.451, 95% CI 1.087-1.935, P = 0.011). Patients with SPHK1 over-expression had a poorer prognosis than those with SPHK1 under-expression (P < 0.001 and P = 0.011 for survival and tumor recurrence). Conclusions. SPHK1 might represent a novel and useful prognostic marker of HCC progression in patients with PVTT.