title: Efficacy of TRAIL treatment against HPV16 infected cervical cancer cells undergoing senescence following siRNA knockdown of E6/E7 genes.
abstract: In this study we investigated E6 and E7 oncogenes from the Human Papilloma Virus as targets for siRNA knockdown in order to boost the efficacy of the anti-cancer drug 'tumor necrosis factor-related apoptosis inducing ligand' (TRAIL). SiHa cells were treated with TRAIL following transfection with E6/E7 siRNA and the expression of death receptors DR4 and DR5, cell viability, apoptosis, senescence and cell cycle analysis were undertaken using flow cytometry, MTT viability assay and cellular β-galactosidase activity assays. E6/E7 siRNA resulted in significant upregulation of death receptors DR4 and DR5 but did not result in an enhanced sensitivity to TRAIL. Our results indicate that E6/E7-siRNA induces senescence rather than apoptosis in SiHa cells. The occurrence of senescence in drug resistant cervical cancer cells such as the SiHa cell line by E6/E7 siRNA, among other factors, may prevent TRAIL induced activation of extrinsic and intrinsic pathways that lead to apoptotic cell death. Our findings are significant for combinatorial strategies for cancer therapy since the induction of senescence can preclude apoptosis rendering cells to be recalcitrant to TRAIL treatment.
authors.affiliation: Center for Bioelectronics and Biosensors, The Biodesign Institute at Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Seron
authors.initials: S
authors.lastname: Eaton
authors.forename: Peter
authors.initials: P
authors.lastname: Wiktor
authors.forename: Derek
authors.initials: D
authors.lastname: Thirstrup
authors.forename: Douglas
authors.initials: D
authors.lastname: Lake
authors.forename: Vinay Janthakahalli
authors.initials: VJ
authors.lastname: Nagaraj
mesh_terms: D045744:Cell Line, Tumor; D016922:Cellular Senescence / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D055785:Gene Knockdown Techniques; D052162:Human papillomavirus 16; D006801:Humans; D009856:Oncogene Proteins, Viral / Q000037:antagonists & inhibitors* / Q000235:genetics; D050725:Papillomavirus E7 Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D030361:Papillomavirus Infections / Q000188:drug therapy / Q000628:therapy*; D034741:RNA, Small Interfering / Q000235:genetics; D012097:Repressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000627:therapeutic use*; D014162:Transfection; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy / Q000628:therapy*
chemical_list: C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C059731:oncogene protein E7, Human papillomavirus type 16