Inhibition of human papillomavirus-16 long control region activity by interferon-gamma overcome by p300 overexpression

Extrachromosomal HPV-16 LCR transcriptional activation by HDACi opposed by cellular differentiation and DNA integration

Histone deacetylase inhibitors (HDACi) have been shown to render HPV-carrying cells susceptible to intrinsic and extrinsic apoptotic signals. As such, these epigenetic drugs have entered clinical trials in the effort to treat cervical cancer. Here, we studied the effect of common HDACi, with an emphasis on Trichostatin A (TSA), on the transcriptional activity of the HPV-16 Long Control Region (LCR) in order to better understand the impact of these agents in the context of the HPV life cycle and infection. HDACi strongly induced transcription of the firefly luciferase reporter gene under the control of the HPV-16 LCR in a variety of cell lines. In the HaCaT keratinocyte cell line undergoing differentiation induced by TSA, we observed a reduction in LCR-controlled transcription. Three major AP-1 binding sites in the HPV-16 LCR are involved in the regulation by TSA. However, whatever the status of differentiation of the HaCaT cells, TSA induced integration of extra-chromosomal transfected DNA into the cellular genome. Although these data suggest caution using HDACi in the treatment of HR HPV infection, further in vivo studies are necessary to better assess the risk.

Human papillomavirus type 56 polymorphism in Canadian women with and without cervical lesions

BACKGROUND

The genomic diversity of high-risk human papillomaviruses (HPV) has been associated with viral persistence and HPV-induced lesions. Studies on HPV56 persistence are still pending.

OBJECTIVE

To assess the association between HPV56 polymorphism and HPV56 persistence and presence of high-grade cervical intraepithelial neoplasia (CIN2,3) or cancer.

STUDY DESIGN

HPV56-positive cervical specimens from 204 women selected from a total of 4669 participants recruited in 5 epidemiological studies (parent studies) were further analyzed by PCR-sequencing of the long control region (LCR).

RESULTS

Of the 81 women followed prospectively in cohort studies who could be classified, 34 had persistent and 47 had transient HPV56 infections. Variant HPV56-LCR-MTL-21 was detected more frequently in persistent infections (52.9%, 95% CI: 36.7-68.6%) than in transient infections (25.5%, 95% CI: 15.1-39.4). Considering only women recruited in a cohort of women infected or at high risk for HIV infection, infection with variant HPV56-LCR-MTL-21 (OR=4.4, 95% CI: 1.3-14.5) was significantly associated with HPV56 persistence controlling in multivariate analysis for high risk HPV detection and HIV infection. A variation at nucleotide 7800 in HPV56-LCR-MTL-21 resulted in the loss of a binding site for Elf-1 embedded in one of the E2 binding sites, a potential activator or repressor of expression of the HPV genome. HPV56 polymorphism was not associated with CIN2,3 or cancer in women enrolled in cross-sectional and case-control studies.

CONCLUSION

Polymorphism in HPV56 may influence the risk that infections with this type will persist.

Salivary mucoepidermoid carcinoma: demonstration of transcriptionally active human papillomavirus 16/18

Herein we test the following hypotheses: (1) High-risk Human Papillomavirus (HR-HPV) may be involved in the etiology of mucoepidermoid carcinoma (MEC), and (2) The detection rate of HR-HPV in MEC has been increasing over time. Ninety-eight archival MEC specimens from three institutions spanning three decades were studied for HPV16/18 E6/E7 transcripts. RNA was extracted from formalin-fixed paraffin embedded specimens and HPV16/18 E6/E7 expression assessed by nested reverse transcription polymerase chain reaction (RT-PCR). A subset of MEC were also studied for MECT1-MAML2 fusion transcripts by nested RT-PCR and amplicon sequencing. The HPV expression data was validated by immunofluorescence (IF) with monoclonal HPV16/18 E6 antibody, PCR with the GP5+/6+ consensus primers, and sequencing of RT-PCR amplicons. HPV genome was localized by in-situ hybridization with the Ventana Inform HPVIII Family 16 probe. P16(INK4a) overexpression and aberrant p53 expression were assessed by immunohistochemistry. HPV16 E6/E7 transcripts were demonstrated in (29/98) 30% of MEC by RT-PCR. HPV18 E6/E7 transcripts were demonstrated in 13/98 (13%) of MEC by RT-PCR. Seven of 98 tumors (7%) demonstrated both HPV16/18. No significant association was found between HPV status and gender, age, and tumor site. All 13 HPV18+ MEC were diagnosed between 2001 and 2010, whereas 45 MEC diagnosed from 1977 to 2000 were negative for HPV18 (p = 0.002). By contrast, there was no significant difference with respect to HPV16 detection and date of diagnosis. All MEC that were positive for E6 protein were also HPV16/18 positive by RT-PCR. Sequencing a subset of RT-PCR amplicons confirmed HPV type- and region-specific sequences. PCR using GP5+/6+ consensus primers demonstrated HPV status concordance in 9 of 10 cases. DNA degradation was present in the last case; the RT-PCR amplicons were sequenced from this case which confirmed the presence of HPV type- and region-specific sequences. Strong (+4/+4) and diffuse (>50%) nuclear and cytoplasmic p16 expression was seen in 64% of MEC in the glandular regions, and 18% of MEC in the solid, squamoid regions. No correlation was seen between p16 expression and HPV status. Twenty-nine MEC (22 HPV+ and 7 HPV-negative) were selected for further evaluation for p53 expression. Strong aberrant nuclear p53 expression was present in only 2/22 HPV + MEC (9%, both Grade 3); no HPV-negative MEC demonstrated aberrant p53 expression. MECT1-MAML2 fusion transcripts were demonstrated in 23/37 (62%) MEC. No significant association was found between the presence of the MECT1-MAML2 fusion transcripts and tumor grade, HPV status, gender, era of diagnosis (2000 and earlier vs. 2001-2010) or tumor site. We demonstrate for the first time that transcriptionally active HPV16/18 is common to MEC. These findings were validated by demonstrating concordant results by separate PCR with consensus primers, and/or confirming the presence of HPV type- and region-specific sequences in the RT-PCR amplicons. We also visualized E6 viral oncoprotein and HPV genome within tumor cells. HR-HPV is thus potentially implicated in the pathogenesis of MEC. The frequency of HPV18 detection is significantly increased in MEC diagnosed after 2001, whereas we found no differences in the HPV16 detection rates per era of diagnosis.

Local expression of interferon-alpha and interferon receptors in cervical intraepithelial neoplasia

PURPOSE

The present study evaluated mRNA expression of interferon-alpha (IFN-alpha), IFN-alpha receptor subunits (IFNAR-1 and IFNAR-2) and an IFN-stimulated gene encoding the enzyme 2',5'-oligoadenylate synthetase (2'5'OAS) in biopsies on patients with varying grades of cervical intraepithelial neoplasia (CIN I, II and III).

METHODS

Uterine cervix biopsies were collected from women with CIN I, II and III (n = 28) and controls without CIN lesions or human papilloma virus (HPV) infection (n = 17). The presence of high and low-risk HPV DNA was determined using hybrid capture. The mRNA levels of IFNAR-1, IFNAR-2, IFN-alpha and 2'5'OAS were determined by RT-PCR with specific primers.

RESULTS

The control group exhibited a greater frequency of IFNAR-1 expression (10/17; 58.3%) than the CIN samples (4/28; 14.2%) (P = 0.0018), while, the expression of IFNAR-2 was also greater in the control samples (11/17; 64.7%) than in the patients with lesions (2/28; 7.1%) (P = 0.0018). Importantly, simultaneous expression of both receptors was observed only in the control group (8/17; 47.0%) (P = 0.0001). Among the CIN samples, there was one case of low expression of mRNA of IFNAR-1 and IFNAR-2. IFN-alpha was present in 14.2% (4/28) of the CIN samples but was not expressed in the control group. mRNA 2'5'OAS were expressed in 28.5% (8/28) of the CIN samples and 11.7% (2/17) of the control samples (not statistically significant). Fifty percent (14/28) of the CIN samples were positive for HPV DNA.

CONCLUSIONS

Cervical biopsy samples from control women or those without neoplasia or HPV infection displayed higher IFN-alpha receptor expression than those with CIN, while simultaneous expression of both IFN-alpha receptor subunits was found only in the control group. There was no significant difference in mRNA expression of IFN-alpha and 2'5'OAS between the control and CIN groups. Then we concluded that the samples obtained from patients with CIN present low levels of the IFN-alpha receptor mRNA.

A cell-based high-throughput assay for screening inhibitors of human papillomavirus-16 long control region activity

Cervical carcinomas express human papillomavirus (HPV) E6 and E7 oncoproteins, which are required to maintain the proliferative state of cancer cells. Repression of E6 and E7 expression results in acquisition of senescent phenotype and in the rescue of functional p53 and p105(Rb) pathways; therefore, therapies directed against either viral protein may be beneficial. However, the systems to study HPV in vitro are technically difficult and not convenient for screening of antiviral compounds. This has hampered the discovery of drugs against HPV. Here we describe the generation and use of a high-throughput screening system based on keratinocytes stably transfected with a reporter construct containing the regulatory sequence of E6 and E7 gene transcription (LCR) that allows easy detection of inhibitors of E6 and E7 expression in libraries of synthetic or biological compounds. The assay was used to screen a wide panel of cytokines: among them, IL-4, IL-13, TGF-beta1, TGF-beta2, TGF-beta3, TNF-alpha, IFN-alpha, and IFN-beta were found to induce a strong inhibition of the LCR activity. Our assay provides a validated tool in the search for drugs against HPV-associated cervical carcinomas and allowed the first systematic analysis of the effect of cytokines on the HPV-16 LCR transcriptional activity.

Long-term follow-up of patients treated with recombinant human interferon gamma for cervical intraepithelial neoplasia

OBJECTIVES

The immediate results of interferon gamma (IFN-gamma) treatment in the management of cervical intraepithelial neoplasia (CIN) have been described. However, little is known of the long-term results of this conservative treatment and we aimed to assess them.

METHODS

We conducted a 5-year follow-up of 13 women with either complete response to intracervical administration of 6,000,000 IU of IFN-gamma (remission from human papilloma virus-induced CIN occurred in nine cases) or partial response (a lower grade of CIN and/or HPV clearance was achieved in four cases).

RESULTS

We performed Papanicolaou smears and colposcopic examinations every 3 months for the first 2 years and every 6 months for the next 3 years. We found three cases of relapse of stage 1 CIN (CIN I), for a recurrence rate of 33.3%, and three cases of complete remission in four subjects with initial diagnosis of partial response. This allowed us to assess the overall lesion-free rate at 53% for the entire group of patients who had CIN I and CIN II treated with IFN-gamma.

CONCLUSIONS

Immunomodulation therapy with IFN-gamma has a high long-term efficacy; however, it is inferior to that of surgery.

Down-regulation of human papillomavirus E6/E7 oncogene by arsenic trioxide in cervical carcinoma cells

Arsenic trioxide (As2O3) has been implicated as a promising anticancer agent for treatment of many cancers including acute promylocytic leukemia. However, the molecular mechanisms are not yet fully defined in solid tumor cells, especially cervical cancer cells carrying human papillomavirus (HPV) genome. To analyze detailed mechanisms in vitro, we treated As2O3 to transformed HeLa cells, a well-studied cervical cancer cell line carrying HPV-18 sequence, and investigated its antiproliferative, antiviral and antimetastatic effects. As2O3 reduced survival and growth of HeLa cells in a dose- and time-dependent manner. Several indicatives of apoptosis were demonstrated by DNA fragmentation assay, DAPI nuclear staining and FACS analysis, respectively. Protein levels of p53 and cleavage of poly(ADP)-ribose polymerase were increased in a dose-dependent manner following treatment of As2O3. In parallel, semi-quantitative reverse transcription-polymerase chain reaction showed that the treatment inhibited HPV-18 E6/E7 viral gene expression in HeLa cells. Using transient transfection and CAT ELISA, we also found that AP-1 sites, located proximal to HPV-18 upstream regulatory region (URR) promoter, could be the major target sites for As2O3. Furthermore, As2O3-treated HeLa cells showed lesser capacity of invasion than those of untreated cells by in vitro invasion assay. Taken together, we proposed that antiviral effect, i.e. down-regulation of HPV E6/E7 oncogenes through targeting for AP-1 sites located in HPV URR might be associated with antiproliferative effect, i.e. induction of apoptosis as be resulted from the accumulation of p53, and that antimetastatic effect could be due to the targeted inactivation of AP-1, a transcription factor required for the expression of MMP-1 and -3. Therefore, our finding may provide a logical basis for the development of a new agent treating HPV-associated cervical neoplasia.