Dataset Information

5-aza-2'-deoxycytidine (DAC) treatment downregulates the HPV E6 and E7 oncogene expression and blocks neoplastic growth of HPV-associated cancer cells.

ABSTRACT: High-risk human papillomaviruses (hr HPVs) may cause various human cancers and associated premalignant lesions. Transformation of the host cells is triggered by overexpression of the viral oncogenes E6 and E7 that deregulate the cell cycle and induce chromosomal instability. This process is accompanied by hypermethylation of distinct CpG sites resulting in silencing of tumor suppressor genes, inhibition of the viral E2 mediated control of E6 and E7 transcription as well as deregulated expression of host cell microRNAs. Therefore, we hypothesized that treatment with demethylating agents might restore those regulatory mechanisms. Here we show that treatment with 5-aza-2'-deoxycytidine (DAC) strongly decreases the expression of E6 and E7 in a panel of HPV-transformed cervical cancer and head and neck squamous cell carcinoma cell lines. Reduction of E6 and E7 further resulted in increased target protein levels including p53 and p21 reducing the proliferation rates and colony formation abilities of the treated cell lines. Moreover, DAC treatment led to enhanced expression of tumor the suppressive miRNA-375 that targets and degrades E6 and E7 transcripts. Therefore, we suggest that DAC treatment of HPV-associated cancers and respective precursor lesions may constitute a targeted approach to subvert HPV oncogene functions that deserves testing in clinical trials.

SUBMITTER: Stich M

PROVIDER: S-EPMC5581016 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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5-aza-2'-deoxycytidine (DAC) treatment downregulates the HPV E6 and E7 oncogene expression and blocks neoplastic growth of HPV-associated cancer cells.

Stich Maximilian M Ganss Lennard L Puschhof Jens J Prigge Elena-Sophie ES Reuschenbach Miriam M Guiterrez Ana A Vinokurova Svetlana S von Knebel Doeberitz Magnus M

Oncotarget 20160716 32

High-risk human papillomaviruses (hr HPVs) may cause various human cancers and associated premalignant lesions. Transformation of the host cells is triggered by overexpression of the viral oncogenes E6 and E7 that deregulate the cell cycle and induce chromosomal instability. This process is accompanied by hypermethylation of distinct CpG sites resulting in silencing of tumor suppressor genes, inhibition of the viral E2 mediated control of E6 and E7 transcription as well as deregulated expression ...[more]

PMID: 28881717

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Project description:BackgroundHuman papillomavirus (HPV) E6 and E7 oncoproteins play a crucial role in HPV-related diseases, such as cervical cancer, and can be used as ideal targets for therapeutic vaccines. Human leukocyte antigen (HLA) participates in the immune response to block HPV infection and invasion by its target/recognition function. HPV-33 and HPV-58 are highly prevalent among Chinese women. Therefore, it is of great significance to study the E6 and E7 region-specific gene polymorphisms of HPV-33 and HPV-58 in Southwest China and to identify ideal epitopes for vaccine design. Both HPV-33 and HPV-58 belong to α-9 genus HPV and are highly homologous, so their correlations are included in our research.MethodsTo study the E6 and E7 variations and polymorphisms of HPV-33 and HPV-58 in Southwest China, we collected samples, extracted and sequenced DNA, and identified variants. Nucleotide sequences were translated into amino acids by Mega 6.0 software. The physical/chemical properties, amino acid-conserved sequences and secondary structure of protein sequences were analysed by the Protparam server, ConSurf server and PSIPRED software. The T and B cell epitopes of the E6/E7 reference and variant sequences in HPV-33 and HPV-58 were predicted by the Immune Epitope Database (IEDB) analysis server and the ABCpred server, respectively.ResultsFive and seven optimal HLA-I restricted T cell epitopes were selected from HPV-33 and HPV-58 E6, respectively, and these optimal epitopes are mainly located in 41-58EVYDFAFADLTVVYREGN of HPV-33 E6 and 40-60SEVYDFVFADLRIVYRDGNPF of HPV-58 E6. Six optimal HLA-I-restricted T cell epitopes were selected from HPV-33 and HPV-58 E7, and these epitopes are mainly located in 77-90RTIQQLLMGTVNIV of HPV-33 E7 and 78-91RTLQQLLMGTCTIV of HPV-58 E7.ConclusionsHPV-33/HPV-58 E6/E7 gene polymorphisms and T/B cell epitopes of their reference and variant sequences were studied, and candidate epitopes were selected by bioinformatics techniques for therapeutic vaccine design for people in Southwest China. This study was the first to investigate the correlation of epitopes between HPV-33 and HPV-58. After experimental validation, these selected epitopes will be employed to induce a wide range of immune responses in heterogeneous HLA populations.

Project description:BACKGROUD:Variations in HPV LCR/E6/E7 have been shown to be associated with the viral persistence and cervical cancer development. So far, there are few reports about the polymorphisms of the HPV-58 LCR/E6/E7 sequences in Southwest China. This study aims to characterize the gene polymorphisms of the HPV-58 LCR/E6/E7 sequences in women of Southwest China, and assess the effects of variations on the immune recognition of viral E6 and E7 antigens. METHODS:Twelve LCR/E6/E7 of the HPV-58 isolates were amplified and sequenced. A neighbor-joining phylogenetic tree was constructed by MEGA 7.0, followed by the secondary structure prediction of the related proteins using PSIPRED v3.3. The selection pressure acting on the HPV-58 E6 and E7 coding regions was estimated by Bayes empirical Bayes analysis of PAML 4.8. Meanwhile, the MHC class-I and II binding peptides were predicted by the ProPred-I server and ProPred server. The transcription factor binding sites in the HPV-58 LCR were analyzed using the JASPAR database. RESULTS:Twenty nine SNPs (20 in the LCR, 3 in the E6, 6 in the E7) were identified at 27 nucleotide sites across the HPV-58 LCR/E6/E7. From the most variable to the least variable, the nucleotide variations were LCR > E7 > E6. The combinations of all the SNPs resulted in 11 unique sequences, which were clustered into the A lineage (7 belong to A1, 2 belong to A2, and 2 belong to A3). An insertion (TGTCAGTTTCCT) was found between the nucleotide sites 7280 and 7281 in 2 variants, and a deletion (TTTAT) was found between 7429 and 7433 in 1 variant. The most common non-synonymous substitution V77A in the E7 was observed in the sequences encoding the α-helix. 63G in the E7 was determined to be the only one positively selected site in the HPV-58 E6/E7 sequences. Six non-synonymous amino acid substitutions (including S71F and K93 N in the E6, and T20I, G41R, G63S/D, and V77A in the E7) were affecting multiple putative epitopes for both CD4+ and CD8+ T-cells. In the LCR, C7265G and C7266T were the most variable sites and were the potential binding sites for the transcription factor SOX10. CONCLUSION:These results provide an insight into the intrinsic geographical relatedness and biological differences of the HPV-58 variants, and contribute to further research on the HPV-58 epidemiology, carcinogenesis, and therapeutic vaccine development.

Dataset Information

5-aza-2'-deoxycytidine (DAC) treatment downregulates the HPV E6 and E7 oncogene expression and blocks neoplastic growth of HPV-associated cancer cells.

Publications

5-aza-2'-deoxycytidine (DAC) treatment downregulates the HPV E6 and E7 oncogene expression and blocks neoplastic growth of HPV-associated cancer cells.

Similar Datasets

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