title: Silencing of human papillomavirus (HPV) E6/E7 oncogene expression affects both the contents and the amounts of extracellular microvesicles released from HPV-positive cancer cells.
abstract: The human papillomavirus (HPV) E6/E7 oncogenes play a crucial role in the HPV-induced carcinogenesis. In this study, the authors investigated whether silencing of endogenous HPV E6/E7 expression may influence the contents or amounts of extracellular microvesicles (eMVs) released from HPV-positive cancer cells. It was found that eMVs secreted from HeLa cells are enriched for Survivin protein. RNA interference studies revealed that maintenance of both intracellular and microvesicular Survivin amounts was strongly dependent on continuous E6/E7 expression. This indicates that intracellular HPV activities are translated into visible alterations of protein contents in eMVs. Besides Survivin, eMVs from HeLa cells contain additional members of the inhibitor of apoptosis protein (IAP) family (XIAP, c-IAP1 and Livin). In contrast, no evidence for the presence of the HPV E6 and E7 oncoproteins in eMVs was obtained. Moreover, it was found that silencing of HPV E6/E7 expression led to a significant increase of exosomes-representing eMVs of endocytic origin-released from HeLa cells. This effect was associated with the reinduction of p53, stimulation of the p53 target genes TSAP6 and CHMP4C that can enhance exosome production and induction of senescence. Taken together, these results show that silencing of HPV E6/E7 oncogene expression profoundly affects both the composition and amounts of eMVs secreted by HPV-positive cancer cells. This indicates that HPVs can induce molecular signatures in eMVs that may affect intercellular communication and could be explored for diagnostic purposes.
authors.affiliation: Molecular Therapy of Virus-Associated Cancers, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, Heidelberg, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Honegger
authors.forename: Jenny
authors.initials: J
authors.lastname: Leitz
authors.forename: Julia
authors.initials: J
authors.lastname: Bulkescher
authors.forename: Karin
authors.initials: K
authors.lastname: Hoppe-Seyler
authors.forename: Felix
authors.initials: F
authors.lastname: Hoppe-Seyler
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D016922:Cellular Senescence / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism; D055354:Exosomes / Q000378:metabolism*; D006367:HeLa Cells; D052161:Human papillomavirus 18 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D010088:Oxidoreductases; D030361:Papillomavirus Infections; D034622:RNA Interference; D034741:RNA, Small Interfering; D000077022:Survivin; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: C107489:BIRC5 protein, human; C541008:CHMP4C protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C052603:E6 protein, Human papillomavirus type 18; C052633:E7 protein, Human papillomavirus type 18; D056827:Endosomal Sorting Complexes Required for Transport; D051034:Inhibitor of Apoptosis Proteins; D015513:Oncogene Proteins; D009856:Oncogene Proteins, Viral; D034741:RNA, Small Interfering; D000077022:Survivin; D016159:Tumor Suppressor Protein p53; D010088:Oxidoreductases; C486677:STEAP3 protein, human; D000110:Acetylcholinesterase
keywords: HPV; Survivin; cervical cancer; exosomes; senescence; tumor virology