Human papillomavirus type 16 E6 suppresses microRNA-23b expression in human cervical cancer cells through DNA methylation of the host gene C9orf3

Oncotarget. 2017 Feb 14;8(7):12158-12173. doi: 10.18632/oncotarget.14555.

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

  • Aminopeptidases / genetics*
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Azacitidine / analogs & derivatives
  • Azacitidine / pharmacology
  • Blotting, Western
  • Cell Line, Tumor
  • DNA (Cytosine-5-)-Methyltransferase 1
  • DNA (Cytosine-5-)-Methyltransferases / antagonists & inhibitors
  • DNA (Cytosine-5-)-Methyltransferases / genetics
  • DNA (Cytosine-5-)-Methyltransferases / metabolism
  • DNA Methylation*
  • Decitabine
  • Enzyme Inhibitors / pharmacology
  • Female
  • Gene Expression Regulation, Neoplastic*
  • HCT116 Cells
  • Human papillomavirus 16 / genetics
  • Human papillomavirus 16 / metabolism
  • Human papillomavirus 16 / physiology
  • Humans
  • MicroRNAs / genetics*
  • Oncogene Proteins, Viral / genetics*
  • Promoter Regions, Genetic / genetics
  • Proto-Oncogene Proteins c-met / genetics
  • Proto-Oncogene Proteins c-met / metabolism
  • RNA Interference
  • Repressor Proteins / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Uterine Cervical Neoplasms / genetics
  • Uterine Cervical Neoplasms / pathology
  • Uterine Cervical Neoplasms / virology

Substances

  • E6 protein, Human papillomavirus type 16
  • Enzyme Inhibitors
  • MIRN23a microRNA, human
  • MicroRNAs
  • Oncogene Proteins, Viral
  • Repressor Proteins
  • Decitabine
  • DNA (Cytosine-5-)-Methyltransferase 1
  • DNA (Cytosine-5-)-Methyltransferases
  • DNMT1 protein, human
  • Proto-Oncogene Proteins c-met
  • AOPEP protein, human
  • Aminopeptidases
  • Azacitidine