(1/83) High-risk but not low-risk HPV E2 proteins bind to the APC activators Cdh1 and Cdc20 and cause genomic instability.
Human papillomaviruses (HPVs) from the high-risk group are associated with cervical cancer, in contrast to HPVs from the low-risk group which are associated with benign lesions of the genital tract. Here, we show that high-risk, but not low-risk HPV E2 proteins, promote a mitotic block, often followed by metaphase-specific apoptosis, and which is independent of the viral oncogenes E6 and E7. High-risk HPV E2-expressing cells also show polyploidy, chromosomal mis-segregation and centrosome amplification leading to genomic instability. We link these defects to a specific and unusually strong interaction between high-risk E2 and both Cdc20 and Cdh1, two activators of the Anaphase Promoting Complex (APC), abnormal localization of Cdh1, and accumulation of APC substrates like cyclin B, in vivo. The finding that high-risk, but not low-risk HPV E2 proteins, induce genomic instability, raises the intriguing possibility that E2 proteins play a role in the oncogenic potential of high-risk papillomaviruses. (+info)
(2/83) Randomized controlled trial of an adjuvanted human papillomavirus (HPV) type 6 L2E7 vaccine: infection of external anogenital warts with multiple HPV types and failure of therapeutic vaccination.
BACKGROUND: Cellular immunity is involved in spontaneous clearance of anogenital warts caused, most typically, by human papillomavirus (HPV) type 6 or 11, supporting the concept of therapeutic vaccination. A therapeutic vaccine composed of HPV-6 L2E7 fusion protein and AS02A adjuvant was evaluated in conjunction with conventional therapies in subjects with anogenital warts. METHODS: A total of 457 subjects with anogenital warts were screened, of which 320 with HPV-6 and/or HPV-11 infection were enrolled into 2 double-blind, placebo-controlled substudies. Three doses of vaccine or placebo were administered along with either ablative therapy or podophyllotoxin. RESULTS: Although a positive trend toward clearance was seen in patients infected with only HPV-6, in neither substudy did the vaccine significantly increase the efficacy of conventional therapies, despite induction of adequate immune responses. Extensive HPV typing by polymerase chain reaction demonstrated that a majority of screened subjects (73.7%) were infected with HPV-6 and/or HPV-11 and that a large proportion (40.1%) were infected with multiple HPV types. HPV types that put subjects at high risk of development of cervical cancer were detected in 39.8% of subjects. CONCLUSIONS: Infection with multiple HPV types, including high-risk types, is common in anogenital wart disease. Therapeutic vaccination failed to increase the efficacy of conventional therapies. (+info)
(3/83) Hyperbaric oxygen inhibits benign and malignant human mammary epithelial cell proliferation.
BACKGROUND: Hyperbaric oxygenation (HBO) therapy is the administration of 100%-inhaled oxygen to patients at increased atmospheric pressure. MATERIALS AND METHODS: We used an in vitro model to examine the effects of HBO on mammary cell proliferation. Normal mammary epithelia, primary tumor and metastatic tumor cells derived from the same patient and immortalized by transfection with the human papilloma virus E6 oncogene, as well as the MCF7 human mammary adenocarcinoma cell line, were studied. RESULTS: HBO (97.9% O2, 2.1% CO2, 2.4 atmospheres absolute) inhibited the proliferation of all 4 cell types as measured by light microscopy, [3H]thymidine uptake, a tetrazolium-based colorimetric assay and a clonogenicity assay. The anti-proliferative effect of HBO was time-dependent (p < 0.01 for all 4 cell types). Hyperoxia alone (95% O2, 5% CO2, 1 atmosphere absolute) and increased atmospheric pressure alone (8.75% O2, 2.1% CO2, 2.4 atmospheres absolute) also inhibited proliferation, but their effects were not as profound as HBO (p < 0.01 when either hyperoxia or increased pressure was compared to HBO for all 4 cell types). HBO enhanced the anti-proliferative effects of melphalan (p < 0.05), gemcitabine (p < 0.001) and paclitaxel (p < 0.001). The clonogenicity assay demonstrated that the effects of HBO were still evident 2 weeks after the exposure (p < 0.01 for all 4 cell types). Experiments using Hoechst-propidium iodide or annexin V-propidium iodide staining showed no HBO-induced increases in necrosis or apoptosis. CONCLUSION: HBO inhibits benign and malignant mammary epithelial cell proliferation, but does not enhance cell death. (+info)
(4/83) High level expression of human epithelial beta-defensins (hBD-1, 2 and 3) in papillomavirus induced lesions.
BACKGROUND: Epithelial defensins including human beta-defensins (hBDs) and alpha-defensins (HDs) are antimicrobial peptides that play important roles in the mucosal defense system. However, the role of defensins in papillomavirus induced epithelial lesions is unknown. RESULTS: Papilloma tissues were prospectively collected from 15 patients with recurrent respiratory papillomatosis (RRP) and analyzed for defensins and chemokine IL-8 expression by quantitative, reverse-transcriptase polymerase chain reaction (RT-PCR) assays. HBD-1, -2 and -3 mRNAs were detectable in papilloma samples from all RRP patients and the levels were higher than in normal oral mucosal tissues from healthy individuals. Immunohistochemical analysis showed that both hBD-1 and 2 were localized in the upper epithelial layers of papilloma tissues. Expression of hBD-2 and hBD-3 appeared to be correlated as indicated by scatter plot analysis (r = 0.837, p < 0.01) suggesting that they were co-inducible in papillomavirus induced lesions. Unlike hBDs, only low levels of HD5 and HD6 were detectable in papillomas and in oral mucosa. CONCLUSION: Human beta-defensins are upregulated in respiratory papillomas. This novel finding suggests that hBDs might contribute to innate and adaptive immune responses targeted against papillomavirus-induced epithelial lesions. (+info)
(5/83) Activation of p53 in cervical cancer cells by human papillomavirus E6 RNA interference is transient, but can be sustained by inhibiting endogenous nuclear export-dependent p53 antagonists.
p53 is degraded in cervical cancer cells by the human papillomavirus E6 and can be stabilized with short interfering RNA (siRNA) molecules targeting E6 mRNA. In this in vitro study, we show that E6 siRNA-induced p53 activation is transient in HeLa cervical cancer cells despite continuous suppression of E6 mRNA; activation can be sustained if the endogenous p53 antagonists COP1, MDM2, Pirh2, and c-Jun-NH(2)-kinase are also targeted by siRNAs or by inhibiting the nuclear export of p53 with leptomycin B. The direct targeting of any one of these four cellular p53 antagonists had no effect on p53 activity when E6 was intact, but inhibited the fading off of E6 siRNA-induced p53 activation in nonstress conditions. The effect was additive when multiple cellular antagonists were concomitantly inhibited, indicating that all these proteins degrade p53 when E6 is inactivated. The antiproliferative effect induced by E6 silencing was enhanced when the endogenous p53 antagonists were additionally targeted. In conclusion, if human papillomavirus E6 is inhibited under nonstress conditions, the subsequent p53 activation is quickly reversed by the endogenous p53 degenerative machinery. The present results indicate that several cellular p53 antagonists must be inhibited for sustained p53 activity if E6 siRNA therapy is attempted and if no combined genotoxic therapy is applied. (+info)
(6/83) The large and small isoforms of human papillomavirus type 16 E6 bind to and differentially affect procaspase 8 stability and activity.
Human papillomavirus type 16 (HPV-16) has developed numerous ways to modulate host-initiated immune mechanisms. The HPV-16 E6 oncoprotein, for example, can modulate the cellular level, and consequently the activity, of procaspase 8, thus modifying the cellular response to cytokines of the tumor necrosis factor family. E6 from HPV-16, but not E6 from the low-risk types 6b and 11, alters the cellular level of procaspase 8 in a dose-dependent manner. Both the large and small (E6*) isoforms of E6, which originate by way of alternate splicing, can modulate procaspase 8 stability. Intriguingly, although both isoforms bind to procaspase 8, the large isoform accelerates the degradation of procaspase 8 while the small isoform stabilizes it. Binding leads to a change in the ability of procaspase 8 to bind either to itself or to FADD (Fas-associated death domain), with the large version of E6 able to inhibit this binding while the small isoform does not. Consistent with this model, knockdown of the large version of E6 by small interfering RNA leads to increases in the levels of procaspase 8 and its binding to both itself and FADD. Thus, these alternatively spliced isoforms can modulate both the level and the activity of procaspase 8 in opposite directions. (+info)
(7/83) Seroprevalence of human papillomaviruses and Chlamydia trachomatis and cervical cancer risk: nested case-control study.
A nested case-control study of invasive and in situ cervical cancer was performed within a community-based cohort of 13,595 Taiwanese women assembled in 1991, with a follow-up period of 9 years. Baseline serum or plasma samples were analysed for antibodies against human papillomavirus (HPV) types 6, 16 and 18 and Chlamydia trachomatis. In total, 114 cases (42 incident cases identified during follow-up and 72 prevalent cases identified at baseline) and 519 matched controls were included in the study. HPV-16 seropositivity was strongly associated with cervical cancer (OR=6.33; 95% CI 3.45-11.62). Overall, C. trachomatis was not associated with cervical cancer, but was associated with cervical cancer in analyses restricted to incident cases of cancer (OR=2.94; 95% CI 1.17-7.42) or to cases in which serum samples were analysed (OR=3.13; 95% CI 1.16-8.47). An antagonistic interaction between HPV-6 and -16 was found in a multiplicative model. These results suggest that different HPV types might interfere in cervical carcinogenesis and that C. trachomatis is associated with cervical cancer in prospective studies, and support the notion that HPV-16 seropositivity is strongly associated with cervical cancer. (+info)
(8/83) Incidence and duration of cervical human papillomavirus 6, 11, 16, and 18 infections in young women: an evaluation from multiple analytic perspectives.
OBJECTIVE: To estimate the incidence and duration of cervical human papillomavirus (HPV)-6, HPV-11, HPV-16, and HPV-18 infections in a population of young American women. METHODS: The study population consisted of U.S. women who at baseline were 16 to 23 years of age, reported zero to five lifetime sexual partners, never having been pregnant, and never having had a prior abnormal Papanicolaou test and were enrolled in the placebo arm of a randomized multicenter clinical trial of a HPV-16 L1 virus-like particle vaccine. Women underwent type-specific endocervical/ectocervical swab HPV DNA testing at approximately 6-month intervals for up to 48 months of follow-up. To contribute person-time in the analyses of type-specific HPV incidence, a woman must have had at least three satisfactory swab specimens available and been negative for the relevant HPV type (HPV-6, HPV-11, HPV-16, or HPV-18) on her first two trial swabs. The duration of incident HPV infections was estimated using Kaplan-Meier survival analysis methods. RESULTS: Person-years of exposure ranged by type-specific analysis from 2,645 to 3,188, with an incidence rate per 100 person-years of 3.6 for HPV-6, 0.4 for HPV-11, 5.4 for HPV-16, and 2.1 for HPV-18. With censoring at the time of treatment for cervical intraepithelial neoplasia, where done, the mean duration of incident infections was 9.3, 8.4, 18.2, and 16.4 months, respectively, for HPV-6 (n = 103), HPV-11 (n = 13), HPV-16 (n = 142), and HPV-18 (n = 62). When the duration of HPV infections was truncated at the time of cervical intraepithelial neoplasia detection (any grade), where applicable, mean duration figures were 8.4, 8.1, 14.0, and 15.1 months for HPV-6, HPV-11, HPV-16, and HPV-18 infections, respectively. CONCLUSIONS: Previous studies of the mean duration of cervical HPV infection have been based on prevalent infections and/or featured relatively short duration of follow-up. This study tested women for HPV infection over a period of up to 48 months and observed a mean duration of incident HPV-16/HPV-18 infections approximately twice that of HPV-6/HPV-11. (+info)