| Background : Hepatocellular Carcinoma(HCC) is the most common malignant tumors of the digestive system. HCC is also a high malignancy with insidious onset, which makes early diagnosis and treatment greatly difficult and results in poor prognosis. Currently, HCC is diagnosed by serology, imaging, biopsy and other methods, but none of these methods is optimal. Early HCC is amenable to surgical resection,and advanced HCC is amenable to transcatheter hepatic arterial chemoembolization(TACE) combined with palliative cares. Thereby, early diagnosis, effective interventions and assessing the prognosis of HCC are great a challenge for patient-healthcare practitioners. Several studies have shown that single nucleotide polymorphism(SNP) might be related to the pathogenesis and prognosis of HCC. In the present study, we aimed to study the SNPs of gene, and expected to find a more effective marker to guide clinical diagnosis and treatment of HCC.Biorhythm is a ubiquitous life phenomenon in eukaryotes,which is controlled by a series of rhythm-related genes. Currently, NPAS2 and other 9 circadian genes have been located and cloned in human chromosome. As a nuclear transcription factor, NPAS2 has been proved to play an important role in tumorigenesis, tumor progression, tumor metabolism and cell phenotype changes.Abnormally elevation of fatty acid synthesis plays a key role in tumor development. A lot of basic researches have proved that increased fatty acid synthesis in tumor cell can generate a large number of phospholipids, which are materials for formation of cell membranes and lipid signaling molecule. Furthermore, tumor cells membrane can also be changed by increased synthetic lipid synthesis, which contributes to signal transduction, intracellular material transport, invasion and metastasis. In contrast, inhibiting of fatty acid synthesis can significantly inhibit tumor cell proliferation, invasion and metastasis. Recent studies showed that fatty acid synthase related genes was up-regulated in HCC, while inhibiting fatty acid synthase related genes could inhibit the tumor cell proliferation of HCC. These results illustrate the key enzyme of fatty acid synthesis plays an important role in HCC tumorigenesis and development process.SNP is a widespread genetic variation in the genome. Numerous studies have confirmed that many diseases are affected by specific SNP. However,the relationship between SNP and HCC is not clear. Clinical observations found that the prognosis varied greatly in HCC patients after TACE treatment, and the difference of prognosis might be related to SNP. Identifying the SNP which were significantly associated with the prognosis of HCC patients has great values for assessing patient’s prognosis and making optimal treatment programs.Aims: To investigate the relationship between single nucleotide polymorphism in NPAS2 and fatty acid synthase related genes and prognosis of HCC patients after TACE treatment, and to investigate the affect of NPAS2 on synthesis of fatty acids in hepatoma cells.Methods: Blood samples were collected from HCC patients after TACE treatment, and SNP genotyping was performed using Sequenom iPLEX system. The relationship of SNPs(rs2057482, rs1957757 and rs2301113) in NPAS2 and ACACA and prognosis of HCC patients after TACE treatment was analysed by Kaplan-meier survival curve and Cox regression model. The affect of NPAS2 gene on fatty acid synthesis and proliferation in human hepatoma cell lines was also investigated.Results: Part 1.1) Different genotypes of SNP rs1053096 and rs2305160 in NPAS2 were significantly correlated with HCC patients’ prognosis after TACE treatment. 2) For HCC patients after TACE treatment,the genotypes(VV) of SNP rs1053096 and genotypes(WV+VV) of SNP rs2305160 were risk factors of prognosis.3) For HCC patients after TACE treatment,the genotypes(VV) of SNP rs1053096 and genotypes(WV+VV) of SNP rs2305160 exhibited a cumulative effect for prognosis.4)For HCC patients after TACE treatment,the haploid genotype(T_A) and polyploid genotypes(C_T-G_A and T_T-G_A) of SNP rs1053096 and SNP rs2305160 were risk factors of prognosis. Part 2. 1) SNP rs11871275 in ACACA gene and SNP rs9912300 in ACLY gene were significantly correlated with HCC patients’ prognosis after TACE treatment.2) For HCC patients after TACE treatment,the mutation genotypes of SNP rs11871275 in ACACA gene and SNP rs9912300 in ACLY gene exhibited a combined and cumulative effect with high levels of serum AFP on poorer prognosis. Part 3. 1) NPAS2 transcript levels were increase in HCC tissues compared to adjacent tissues.2) Upregulated NPAS2 promoted the synthesis of triglyceride and neutral fat in hepatoma cells.3) Reduced NPAS2 expression inhibited proliferation of hepatoma cells.Conclusion:1)SNP rs1053096 and rs2305160 in NPAS2 are significantly correlated with HCC patients’ prognosis after TACE treatment and have cumulative effect on poorer prognosis.2) SNP rs11871275 in ACACA gene and SNP rs9912300 in ACLY gene are significant correlated with HCC patients’ prognosis after TACE treatment,and they can more accurately predict clinical outcome combined with levels of serum AFP.3)NPAS2 gene might promote hepatoma cells proliferation by up-regulating fatty acid synthesis. |
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