Down-regulation of the gax gene in smooth muscle cells of the splenic vein of portal hypertension patients

BACKGROUND: The expression of gax, an anti-prolifera-tive homeobox gene, is rapidly down-regulated in vascular smooth muscle cells (VSMCs) following arterial injury. Whether the down-regulation of gax is involved in modulating the proliferation of smooth muscle cells of the splenic vein in patients with portal hypertension has not yet been elucidated. The aim of this study was to investigate the expression of the mRNA of the gax gene in smooth muscle cells of the splenic vein in patients with portal hypertension. METHODS: Reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect the expression of gax mRNA and immunohistochemistry staining was performed to demonstrate the expression of PCNA protein in the splenic veins of 28 patients with portal hypertension and those of 12 normal controls. This study was approved by the Institutional Ethics Committee and informed consent was obtained from all participants. RESULTS: RT-PCR showed that the expression of gax mRNA was PCNA-positive and negative in the splenic vein of patients with portal hypertension (1.08 ± 0.04 and 1.39 ± 0.27, respectively). There was a significant difference in the 28 patients compared with the 12 normal controls ( P < 0.01). The relative expression of PCNA protein in the vascular tissues was significantly higher in the experimental group than in the control group. CONCLUSIONS: Down-regulation of gax mRNA and the overexpression of PCNA protein were seen in smooth muscle cells of the splenic vein in patients with portal hypertension, regulating the proliferation, migration and phenoty-pic change and resulting in remodelling of the splenic vein, which may play an important role in the pathogenesis and maintenance of portal hypertension.