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Silencing of integrated human papillomavirus-16 oncogenes by small interfering RNA-mediated heterochromatization

Jayanth Kumar Palanichamy1, Mohit Mehndiratta, Mohita Bhagat

  • 1Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India.

Molecular Cancer Therapeutics
|July 1, 2010
PubMed

Insights

Small interfering RNAs (siRNA) can induce transcriptional gene silencing (TGS) by targeting gene promoters. A specific siRNA effectively silenced human papillomavirus-16 (HPV-16) oncogenes E6 and E7 epigenetically, showing therapeutic potential.

Area of Science:

  • Molecular Biology
  • Epigenetics
  • Virology

Background:

  • Transcriptional gene silencing (TGS) is a process where double-stranded or small interfering RNAs (siRNA) targeting gene promoters reduce gene expression.
  • Human papillomavirus-16 (HPV-16) is associated with cervical and other epithelial cancers, driven by oncogenes E6 and E7.

Purpose of the Study:

  • To identify and characterize siRNAs capable of inducing TGS specifically in HPV-16-positive cells.
  • To investigate the mechanism and specificity of TGS targeting the HPV-16 enhancer.

Main Methods:

  • Screening of multiple siRNAs targeting an NF-1 binding site in the HPV-16 enhancer.
  • Transfection of siRNAs into HPV-16-positive cell lines (siHa and CaSki).
  • Analysis of gene expression, heterochromatization, DNA methylation, and enhancer-associated transcripts.

Main Results:

  • One specific siRNA induced TGS of HPV-16 oncogenes E6 and E7 in HPV-16-positive cell lines.
  • The TGS was specific to the HPV-16 enhancer and associated with heterochromatization.
  • A decrease in an enhancer-associated transcript supported the RNA:RNA model for TGS.

Conclusions:

  • A specific siRNA can epigenetically silence HPV-16 E6 and E7 oncogenes via TGS.
  • This siRNA demonstrates specificity for the HPV-16 enhancer, not affecting HPV-18.
  • The findings suggest a potential therapeutic strategy for HPV-16-associated cancers.

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