Aberrant Promoter Methylation at CpG Cytosines Induce the Upregulation of the E2F5 Gene in Breast Cancer / 한국유방암학회지

PURPOSE: The promoter methylation status of cell cycle regulatory genes plays a crucial role in the regulation of the eukaryotic cell cycle. CpG cytosines are actively subjected to methylation during tumorigenesis, resulting in gain/loss of function. E2F5 gene has growth repressive activities; various studies suggest its involvement in tumorigenesis. This study aims to investigate the epigenetic regulation of E2F5 in breast cancer to better understand tumor biology. METHODS: The promoter methylation status of 50 breast tumor tissues and adjacent normal control tissues was analyzed. mRNA expression was determined using SYBR® green quantitative polymerase chain reaction (PCR), and methylation-specific PCR was performed for bisulfite-modified genomic DNA using E2F5-specific primers to assess promoter methylation. Data was statistically analyzed. RESULTS: Significant (p<0.001) upregulation was observed in E2F5 expression among tumor tissues, relative to the control group. These samples were hypo-methylated at the E2F5 promoter region in the tumor tissues, compared to the control. Change in the methylation status (Δmeth) was significantly lower (p=0.022) in the tumor samples, indicating possible involvement in tumorigenesis. Patients at the postmenopausal stage showed higher methylation (75%) than those at the premenopausal stage (23.1%). Interestingly, methylation levels gradually increased from the early to the advanced stages of the disease (p<0.001), which suggests a putative role of E2F5 methylation in disease progression that can significantly modulate tumor biology at more advanced stage and at postmenopausal age (Pearson's r=0.99 and 0.86, respectively). Among tissues with different histological status, methylation frequency was higher in invasive lobular carcinoma (80.0%), followed by invasive ductal carcinoma (46.7%) and ductal carcinoma in situ (20.0%). CONCLUSION: Methylation is an important epigenetic factor that might be involved in the upregulation of E2F5 gene in tumor tissues, which can be used as a prognostic marker for breast cancer.

Amino acid mutatios of gp41 2F5 and 4E10 neutralizing epitopes of 92 HIV-1 infected individuals and AIDS patients in China / 中华微生物学和免疫学杂志

Objective To study the amino acid mutations in neutralizing antibody 2F5 and 4E10 conserved epitopes ELDKWA and NWFDIT of HIV-1 membrane proximal external region(MPER)in 92 HIV-infected individuals and AIDS patients in China,and to provide a basis for the neutralizing antobodies immunotherapy and a design of vaccines. Methods Nest-PCR methods were used to amplity genes of the HIV-1 env gp41 region.The amplified fragments were sequenced by double-deoxygen terminal method and translated into amino acids for analysis.The mutations of 2F5 and 4E10 neutralizing epitopes were identified by comparison with the epitopes reference data in HIV-1 Sequence Database.Results There were mutations on both 2F5 and 4E10 neutralizing epitopes.2F5 conserved neutralizing epitopes major mutations tocused on E662A(14.1%),K665S(17.4%),A667K(16.3%),and 4E10 conserved neutralizing epltopes major mutations included N671S(13.0%),D674S(3.3%),T676S(16.3%).The mutation rates of 2F5 and 4E10 epitopes were significanfly different between CRF_B'C-clade and B'-clade(P<0.05).The mutata rates of CRF_B'C-clade were higher than that of CRFOI_AE-clade in 2F5 epitopes(P<0.05).The mutation rates of B'-clade in 4E10 eiptopes showed significant difference in slow progressors,HIV-infected individuals and AIDS patients,respectively(P<0.05).Conclusion The HIV-1 patients in China are demonstrated diversified mutations in 2F5 and 4E10 neutralizing epitopes.The mutation degrees of amlno acids in conserved neutralizing epitopes are different in different subtypes.There may be a correlation between neutralizing epitopes mutations of 4E10 with disease progression.