Abstract
Oncogenic protein E6 of human papillomavirus type 16 (HPV-16) is believed to involve in the aberrant methylation in cervical cancer as it upregulates DNA methyltransferase 1 (DNMT1) through tumor suppressor p53. In addition, DNA demethylating agent induces the expression of one of the HPV-16 E6 regulated microRNAs (miRs), miR-23b, in human cervical carcinoma SiHa cells. Thus, the importance of DNA methylation and miR-23b in HPV-16 E6 associated cervical cancer development is investigated. In the present study, however, it is found that miR-23b is not embedded in any typical CpG island. Nevertheless, a functional CpG island is predicted in the promoter region of C9orf3, the host gene of miR-23b, and is validated by methylation-specific PCR and bisulfite genomic sequencing analyses. Besides, c-MET is confirmed to be a target gene of miR-23b. Silencing of HPV-16 E6 is found to increase the expression of miR-23b, decrease the expression of c-MET and thus induce the apoptosis of SiHa cells through the c-MET downstream signaling pathway. Taken together, the tumor suppressive miR-23b is epigenetically inactivated through its host gene C9orf3 and this is probably a critical pathway during HPV-16 E6 associated cervical cancer development.
Keywords:
C9orf3; DNA methylation; HPV-16 E6; cervical cancer; miRNA-23b.
MeSH terms
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Aminopeptidases / genetics*
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Apoptosis / drug effects
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Apoptosis / genetics
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Azacitidine / analogs & derivatives
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Azacitidine / pharmacology
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Blotting, Western
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Cell Line, Tumor
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DNA (Cytosine-5-)-Methyltransferase 1
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DNA (Cytosine-5-)-Methyltransferases / antagonists & inhibitors
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DNA (Cytosine-5-)-Methyltransferases / genetics
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DNA (Cytosine-5-)-Methyltransferases / metabolism
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DNA Methylation*
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Decitabine
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Enzyme Inhibitors / pharmacology
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Female
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Gene Expression Regulation, Neoplastic*
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HCT116 Cells
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Human papillomavirus 16 / genetics
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Human papillomavirus 16 / metabolism
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Human papillomavirus 16 / physiology
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Humans
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MicroRNAs / genetics*
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Oncogene Proteins, Viral / genetics*
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Promoter Regions, Genetic / genetics
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Proto-Oncogene Proteins c-met / genetics
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Proto-Oncogene Proteins c-met / metabolism
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RNA Interference
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Repressor Proteins / genetics*
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Reverse Transcriptase Polymerase Chain Reaction
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Uterine Cervical Neoplasms / genetics
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Uterine Cervical Neoplasms / pathology
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Uterine Cervical Neoplasms / virology
Substances
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E6 protein, Human papillomavirus type 16
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Enzyme Inhibitors
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MIRN23a microRNA, human
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MicroRNAs
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Oncogene Proteins, Viral
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Repressor Proteins
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Decitabine
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DNA (Cytosine-5-)-Methyltransferase 1
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DNA (Cytosine-5-)-Methyltransferases
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DNMT1 protein, human
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Proto-Oncogene Proteins c-met
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AOPEP protein, human
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Aminopeptidases
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Azacitidine