title: Highly potent and specific siRNAs against E6 or E7 genes of HPV16- or HPV18-infected cervical cancers.
abstract: Infection with high-risk types (type 16 or type 18) of human papillomaviruses (HPVs) increases a patient's risk of cervical cancer. Given the importance of the cervix and the severe side effects resulting from traditional cancer therapies, this study aimed to achieve targeted inhibition of viral oncogenes in tumor cells using small interfering RNAs (siRNA). To accomplish this, we developed nine siRNAs against either the E6 or E7 genes of HPV-16 or HPV-18 in several combinations, yielding siRNAs targeting 16E6, 16E7, 18E6 and 18E7. We measured the effectiveness of the siRNAs by examining E6 or E7 mRNA expression after transfection of the siRNAs into HPV-positive CaSki (HPV-16) or HeLa (HPV-18) cell lines. We found that the HPV-siRNAs significantly reduced cell growth and colony formation in both cell lines. Flow cytometry analysis revealed a significant increase in apoptosis. The siRNAs had no effect on cell growth, colony formation or apoptosis in HPV-negative C33A cells, demonstrating a lack of off-target effects. In addition, an in vivo xenograft study showed that intra-tumoral injection of the siRNAs reduced tumor growth in BALB/c nude mice. In conclusion, we have developed highly specific and potent HPV-siRNAs that successfully suppress tumor growth and induce apoptosis in HPV-positive cervical cancer cells. siRNA treatment has potential for further development as an adjuvant therapy for cervical cancer.
authors.affiliation: Department of Radiation Oncology, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: J T-C
authors.initials: JT
authors.lastname: Chang
authors.forename: T-F
authors.initials: TF
authors.lastname: Kuo
authors.forename: Y-J
authors.initials: YJ
authors.lastname: Chen
authors.forename: C-C
authors.initials: CC
authors.lastname: Chiu
authors.forename: Y-C
authors.initials: YC
authors.lastname: Lu
authors.forename: H-F
authors.initials: HF
authors.lastname: Li
authors.forename: C-R
authors.initials: CR
authors.lastname: Shen
authors.forename: A-J
authors.initials: AJ
authors.lastname: Cheng
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D005260:Female; D005814:Genes, Viral; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009856:Oncogene Proteins, Viral / Q000037:antagonists & inhibitors* / Q000235:genetics; D050725:Papillomavirus E7 Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage*; D012097:Repressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D014162:Transfection; D014183:Transplantation, Heterologous; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000628:therapy* / Q000821:virology
chemical_list: D004268:DNA-Binding Proteins; C068651:E6 protein, Human papillomavirus type 16; C052603:E6 protein, Human papillomavirus type 18; C052633:E7 protein, Human papillomavirus type 18; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16