Zinc-finger Protein331Regulated By Promoter Region Hypermethylation In Human Hepatocellular Carcinoma

Objective: Hepatocellular carcinoma (HCC) is the fifth most frequently diagnosedcancer worldwide and the third most frequent cause of cancer death. HCC representsone of the most rapidly spreading cancers in the world with a poor prognosis. However,early diagnosis of the cancer is hard to achieve because patients in the early stage haveno obvious symptoms, and majority of patients diagnosed in hospital are in theadvanced stage. So that early detection is important for the successful treatment ofHCC. To search a molecular biomarker that can be translated to widespread clinicalpractice is currently an area of active research.Cancer can arise from a combination of epigenetic and genetic abnormalities that resultin abnormal gene expression and function. Epigenetic modifications, primarily in theform of DNA hypermethylation of tumor suppressor genes and its related genes, havebeen demonstrated to occur frequently in the processes of HCC tumorigenesis andmetastasis. Differing from genetic alterations, the epigenetic alterations is reversible.So to research the epigenetic change of the cancer is important for its prevention andcure.Zinc-finger protein331(ZNF331), a Kruppel-associated box zinc-finger protein gene,was identified as a putative tumor suppressor in gastric cancer（GC） and multiplemyeloma (MM). In gastric cancer, loss of ZNF331is mainly caused by aberrantpromoter methylation, whereas deletions and mutations of this gene locus are infrequently seen. However, there is no similar report in HCC.The study from epigenetic and transcription level to identify the promoter methylationsituation of ZNF331in the hepatocellular cancer cell lines and to discuss the expressionsituation of ZNF331mRNA respectively. Meanwhile, we analysis its promotermethylation condition in hepatocellular cancer tissues to explore the molecularmechanism of hepatocellular cancer’s development and provide the theoretical basis ondiagnosis, prevention and treatment of hepatocellular cancer.Methods: Five human hepatic cancer cell lines and50cases of human primary hepaticcancer were employed to detect ZNF331promoter region methylation by methylationspecific PCR(MSP). Semi-quantitative RT-PCR was used to examine the expression ofZNF331.Results: Partial methylation was found in HBXF344, PLC/PRF/5, HepG2andBEL-7402cell lines. Unmethylation was found in SNU449cell line. Weak expressionwas found in HBXF344, PLC/PRF/5, HepG2and BEL-7402. ZNF331was expressedin SNU449cell line. Increased expression of ZNF331was found in HBXF344, HepG2,BEL-7402, PLC/PRF/5cell lines after5-Aza treatment. No expression changes wereexamined in SNU449cell line before and after5-Aza treatment. ZNF331wasmethylated in80%(40/50) of primary human hepatic cancer. But no methylation wasfound in normal liver tissues (0/10). No correlation was found between promoterregion methylation and gender, age, AFP level, hepatitis virus infection, tumor size ortumor stage.Conclusion: ZNF331is silenced by promoter region hypermethylation in humanhepatocellular carcinoma. ZNF331is frequently methylated in human primary hepatic cancer.