A Polymorphism At The MiR-502 Binding Site In The 3'-untranslated Region Of The SET8 Gene Is Associated With The Risk And Prognosis Of Epithelial Ovarian Cancer

Objective: Micro RNA(mi RNA)is a highly conservated small no-coding RNA recently years,About 1/3 of protein-coding genes is regulated by mi RNA in the human genome.It usually results in gene-silencing via translational repression or target degradation by base-pairing with complementary sequences of the 3'untranslated region(3'UTR)of a target m RNA.Mi RNA plays important roles in a broad range of biological processes,such as cell proliferation and differentiation,cell apoptosis,hormone secretion,tumorigenesis.Single nucleotide polymorphisms(SNP)is a variation that occurs when a single nucleotide sequence in the genome differs,which is widely distributed in the human genome,and it is the major genetic variation between different individual.SNPs in mi RNA binding sites can alter the expression of target genes,thereby affecting the risk of cancer.SET8,also known as SETD8,PR-SET7 or KMT5 a,encodes a histone H4 lysine 20 monomethyltransferase,The enzyme regulates gene transcription,cell cycle and tumor development by methylation of histone proteins.SNP(rs16917496)exists in the mi R-502 binding site in the 3' untranslated region of the SET8 gene.Studies found that it relate with the early happen of tumor.This study analyzes the relationship of polymorphism at the mi R-502 binding site in the 3' untranslated region of the SET8 gene with the risk,the clinical characteristics and the prognosis of EOC patients and finds new molecular targets for early diagnosis of EOC and to improve the prognosis of EOC patients.Methods:1 Sample collection and following up: This study included 100 patients who received operative treatment in the Second Hospital of Hebei MedicalUniversity between 2008 and 2012.The participants were histologically confirmed primary epithelial ovarian cancer.The patients did not have neoadjuvant chemotherapy or hormonic therapy before surgical treatment.Formalin-fixed,paraffin-embedded tissues for experiment were collected after operation.The patients' clinical characteristics(age,clinical stage,et al)were recorded.We followed up for 3-years survival status of post-operation patients by phones.The follow-up deadline was December 2014.Blood samples for control group were collected from 100 healthy controls at Second Hospital of Hebei Medical University.Patients in control group have complete medical history,with no associated diseases with EOC.2 DNA extraction,amplification and sequencing: The genomic DNA was extracted with Wizard Genomic DNA extraction kit from blood samples.The target gene of qualified DNA samples were then amplified by PCR,the forward primer is 5'-TCACGACGGT GCTACCTAAG-3',and the reverse primer is 5'-CATGCTGGTG TGACACAGTC-3'.The products were confirmed by agarose gel electrophoresis and sequencing.Polymorphisms were confirmed by repeating the analysis on both strands.3 Statistical analysis: Student's t-test was used to analysis measurement data,and ?2 test(Pearson Chi-Square test)was used to analysis enumeration data.The univariate analysis was performed by Kaplan-Meier method and Log-Rank method,the multifactor analysis was done by COX regression model.All analyses were performed by SPSS software 21.0,P<0.05 was considered statistically significant.Results:1 The frequency for each genotype(C/C Vs.T/T,C/C Vs.C/T and C/C Vs.C/T+T/T)were 0.138,0.020,0.048 between EOC patients and controls.Thus,rs16917496 is a cancer risk marker for epithelial ovarian cancer patients.2 The is no association exist for the genotype distribution of rs16917496 and the clinical characteristics of EOC patients.3 The univariate analysis showed that patients with C/C,C/T,T/Tgenotypes had a 3-year survival rate of 80%,74.1%,58.5%,respectively.There was no significant difference of 3-year survival rates between genotpes.4 Multivariate analysis with the Cox proportional hazards model was performed for these survival predictive factors.FIGO stage and tumor residual size were as independent predictors for EOC outcome.Conclusions:1 The polymorphism at the mi R-502 binding site in the 3'UTR of the SET8 genotype was related to the risk of epithelial ovarian cancer.2 SET8 genotype can not be used as the independent risk factor which was correlated with the prognosis of epithelial cancer patients.The different genotypes of rs16917496 targeting in SET8 are not significantly correlated to the different clinical characteristics of epithelial ovarian cancer patients.