Study On The MRNA Expression Of SOX Gene Family In Heptocarcinogenesis

Hepatocellular carcinoma (HCC) is a common malignant cancer. It is the second death of all cancers in China which threaten the health of the population. The development of HCC is a multistep process and associated with multiple factors including virus infection, abnormal gene expression and exposure to alcohol. However, the precise molecular mechanisms of hepatocarcinogenesis remain unknown. The abnormal expression of SOX genes, which act as negative regulators in Wnt/β-catenin signaling pathway, are found to associate with the occurance and development of human tumors including glioma, colorectal and HCC.ObjectivesTo construct the mRNA expression profile of SOX genes and identify the possible relationship between SOX genes and to figure out whether SOX mRNA expression profile is related to the clinical and pathological characteristics of HCC and whether abnormal expression of SOX genes can induce the occurrence and development of HCC.Materials and methods1. Liver-derived tumor cell lines and liver tissues from HCC patientsThe cell lines were composed of Huh-7, PU-PRL-5, Sun-449, SMMC-7721, HepG2, HBx-F344, SK-Hepl.With informed consent obtained from the subjects.7 normal liver tissues,40 pairs of HCC tissues and paracarcinoma tissues were collected from HCC patients. The patients'clinical data were collected by trained students.2. SOX mRNA profiles in candidate samplesReal-time PCR was performed to determine the SOX mRNA levels in HCC cell lines, normal liver tissues, HCC tissues and paracarcinoma tissues. HMBS was quantified as an internal control.3. Data analysisThe SOX mRNA expression differences among HCC cell lines and normal tissue samples were analyzed by Paired-Samples T Test, and that among these HCC tissues and paracacinoma tissues were analyzed by Wilcoxon Signed Ranks Test. Spearman Rank Correlation analytical method was used to study the interactions between SOX gene expression levels. Fisher's Exact Test was used to analyze the association between the abnormal expression of SOX mRNA and clinical factors in 40 pairs of HCC tissues and paracacinoma tissues. P value less than 0.05 is considered signi-ficant. All data analyses were performed by using of SPSS12.0.Results1. SOX mRNA profiles in HCC cell linesThe mRNA expression levels of SOX2, SOX5, SOX6, SOX7, SOX13 and SOX17 were down-regulated in 7 HCC cell lines compared to 7 normal tissue samples, and their differences were statistically significant (t=2.753, P=0.033; t=3.150, P=0.035; t=3.160, P=0.020; t=2.826, P=0.030; t=2.827, P=0.030).2. SOX mRNA profiles in HCC tissues and paracacinoma tissuesA statistically significant down-regulation of SOX2/SOX7, SOX5 and SOX6 was found in 47.5% (19/40),40.0%(16/40),55.0% (22/40) of HCC tissues, respectively, when compared to corresponding paracarcinoma tissues (z=-1.978, P=0.048; z=-1.978, P=0.048; z=-2.755, P=0.006; z=-2.298, P=0.022). In contrast, SOX4 showed its up-regulation with statistical significance in 45.0%(18/40) of HCC tissues compared to paracarcinoma tissues (z=-2.097, P=0.036).3. Relationship among SOX genesSpearman Rank Correlation analysis showed that there is a significant correlation between SOX9 and SOX4, SOX13 and SOX5, SOX7 and SOX17, respectively, when compared the SOX mRNA profile before the occurence of HCC to the situation when the patients get HCC. While the correlation between SOX17and SOX4/SOX13, SOX7 and SOX4/SOX6/SOX9/SOX13, SOX2 and SOX4, SOX6 and SOX5/SOX13 (members from the same SOXD with SOX6), respectively, become weaker and even disappear as HCC occurrences and developments in an aggressive way.4. Relationship between SOX mRNA expression levels and the clinical and patho-logical characteristics in HCCFisher's Exact Test analysis suggested that SOX2, SOX7 and SOX9 express abnormally in HCC, which were related to HCC clinical stage (X2=7.087, P=0.028; X2=8.319, P=0.013;X2=5.868, P=0.046). The expression levels of SOX2 and SOX9 correlated to cirrhosis (X2=9.035, P=0.009;X2=7.203, P=0.021). Besides, SOX5 could promote the portal vein thrombus' genesis (X2=7.968, P=0.017), while SOX9 played an important role in the metastasis of HCC (X2=7.286, P=0.025).Conclusion1. SOX gene family express abnormally in HCC. They may stimulate the canonical Wnt/β-catenin signaling pathway and thereby contribute to carcinogenesis.2. It is presumed that SOX gene family may play a critical role in the development of HCC via their interaction with each other.3. The abnormal expression of SOX mRNA may be related to clinical stage, cirrhosis, portal vein thrombus'genesis, metastasis of HCC.