Expressing HPV16 E7 Research Articles

The Mechanism of HPV-mediated DNA Methylation in the Promoter Region of Long-chain Non-coding RNA MAGI2-AS3 in the Occurrence and Development of Cervical Cancer

Background: Cervical cancer, a malignancy of gynecological origin, typically necessitates a therapeutic approach combining surgery and chemoradiotherapy as the primary intervention. However, the 5-year survival rate remains suboptimal, prompting researchers to explore novel strategies for the early diagnosis and treatment of cervical cancer. This study delves into the investigation of human papillomavirus (HPV)-mediated DNA methylation modifications within the promoter region of the long non-coding RNA MAGI2-AS3 during cervical cancer development. This paper is an experimental study, laboratory based, using cell lines. Methods: A lentivirus overexpression vector encoding HPV16 E6/E7 proteins was established for transfecting cervical epithelial cells. The methylation status of DNA in the MAGI2-AS3 promoter region was assessed using MassARRAY, and the MAGI2-AS3 gene expression was measured through quantitative real time polymerase chain reaction (qRT-PCR). Subsequently, the correlation between methylation levels and gene expression in cervical cancer was analyzed. Results: (1) Relative to the HPV-negative cervical cancer cell line C33A, MAGI2-AS3 expression significantly decreased in the HPV-positive cervical cancer cell line Siha. (2) The methylation rate of 16 CpG sites in the HPV-positive cervical cancer cell line Siha was notably higher compared to the HPV-negative cervical cancer cell line C33A. (3) To further substantiate the regulatory impact on DNA methylation and expression within the MAGI2-AS3 promoter region, we silenced the expression of HPV16 E6 in the HPV-positive cervical cancer cell line Siha using HPV16 E6 siRNA. The ensuing qRT-PCR analysis revealed a significant up-regulation of MAGI2-AS3 expression in the HPV16 E6 siRNA group when contrasted with the negative control group. MassARRAY analysis was employed to gauge the DNA methylation levels in the promoter region of the MAGI2-AS3 gene in HPV-positive cervical cancer cells (Siha) following HPV16 E6 silencing. The results demonstrated a significantly lower methylation rate at the CpG_29 site in the HPV16 E6 siRNA group compared to the HPV16 E6 siRNA group. Conclusions: The study establishes a close association between HPV infection and elevated methylation levels coupled with diminished expression of MAGI2-AS3. The influence of HPV infection on the malignant transformation of cervical epithelial cells is potentially mediated through the regulatory modulation of MAGI2-AS3 expression via DNA methylation.

Characterization of novel compounds that directly bind to and inactivate the HPV E6 protein for treatment of HPV-associated cervical and oropharyngeal cancers.

e15122 Background: The human papillomavirus (HPV) E6 protein is necessary for viral genome replication and is always expressed in HPV-induced malignancies. We performed in silico screening of chemical libraries for molecules that bind to a pocket on the cancer associated HPV-16 E6 protein. We focused on the protein-protein interaction of E6 with one of its cellular binding partners, the ubiquitin ligase E6AP. In a trimolecular complex with E6, E6AP ubiquitinates p53, leading to its destruction by the proteasome. We designed, synthesized, and characterized >300 compounds that 1) bind to the E6AP interaction surface of the HPV-16 E6 protein; 2) are armed with a ‘warhead’ to make an irreversible bond with a specific cysteine in this HPV-16 E6 binding pocket; 3) and restore levels of p53 and selectively decrease viability of HPV-16 expressing tumor derived cells. Methods: E6 inhibitor optimization was guided by in silico docking strategies, co-crystallization, and medicinal chemistry, followed by biochemical and cellular assays to iteratively design and synthesize molecules with increased E6 inhibitory activities. Results: We used whole protein mass spectrometry to interrogate covalent bonding to E6, showing irreversible binding to the cysteine in the targeted E6 binding pocket without the other 13 cysteines in E6, with Ki in the range of seconds. Biolayer interferometry and fluorescence polarimetry measured blockade of E6 with E6AP, with IC50 in the range of 400-600 nM. To establish in cell inactivation of E6, human cervical cancer derived SiHa cells that express HPV-16 E6 were incubated with compounds, showing dose dependent increase of p53 levels up to 8-fold after 24 hrs, an effect that was not observed in the HPV-16- cell line RPE-1 expressing wild-type p53. Viability of two cervical (SiHa, CaSki) and two oropharyngeal HPV-16+ cancer cell lines (UM-SC-47, UM-SCC-104) was reduced with an IC50 of ~2-3 µM, with an IC50>30µM in RPE-1 cells and telomerase immortalized human keratinocytes. These in vitro and cell-based experiments revealed dependence on the cysteine residue in the E6AP binding pocket of E6. For in vivo proof-of-concept studies, we developed mouse xenograft models, performed by engrafting SiHa, UM-SC-47 and UM-SCC-104 cancer derived cells subcutaneously into the flank of immunodeficient mice. Lead compounds were administered by intraperitoneal injection and demonstrated nearly complete inhibition (> 70% tumor reduction) in HPV-16 tumor growth compared to vehicle. Anti-tumor activity was not observed with the HPV-negative tumor cell line C33A. Conclusions: HPV-16 is identified in about 50% of all cervical cancers and the majority of head and neck malignancies. Inactivation of the HPV E6 protein represents the opportunity for a novel molecular targeted approach for medical treatment of HPV-16 expressing cancers of the cervix and oropharynx.

HPV16 E7 modulates the cell surface expression of MET and CD109 via the AP2 complex

Multiple cellular pathways are affected by HPV E6 and E7 oncoproteins, including endocytic and cellular trafficking. HPV-16 E7 can target the adaptor protein (AP) complex, which contains proteins important during endocytosis transport. To further investigate the role of HPV E7 during this process, we analysed the expression of cell surface proteins in NIKS cells expressing HPV-16 E7. We show that different cell surface proteins are regulated by HPV-16 E7 via interaction with AP2. We observed that the expression of MET and CD109 membrane protein seems to be upregulated in cells expressing E7. Moreover, the interaction of MET and CD109 with AP2 proteins is disrupted by HPV-16 E7. In addition, in the absence of HPV-16 E7, there is a downregulation of the cell membrane expression of MET and CD109 in HPV-positive cell lines. These results expand our knowledge of the functions of E7 and open new potential cellular pathways affected by this oncoprotein.

Human papillomavirus-16 E6 activates the pentose phosphate pathway to promote cervical cancer cell proliferation by inhibiting G6PD lactylation

High-risk human papillomaviruses (HPVs) are the causative agents of cervical cancer. Here, we report that HPV16 E6E7 promotes cervical cancer cell proliferation by activating the pentose phosphate pathway (PPP). We found that HPV16 E6 activates the PPP primarily by increasing glucose-6-phosphate dehydrogenase (G6PD) enzyme activity. Mechanistically, HPV16 E6 promoted G6PD dimer formation by inhibiting its lactylation. Importantly, we suggest that G6PD K45 was lactylated during G6PD-mediated antioxidant stress. In primary human keratinocytes and an HPV-negative cervical cancer C33A cells line ectopically expressing HPV16 E6, the transduction of G6PD K45A (unable to be lactylated) increased GSH and NADPH levels and, correspondingly, decreasing ROS levels. Conversely, the re-expression of G6PD K45T (mimicking constitutive lactylation) in HPV16-positive SiHa cells line inhibited cell proliferation. In vivo, the inhibition of G6PD enzyme activity with 6-aminonicotinamide (6-An) or the re-expression of G6PD K45T inhibited tumor proliferation. In conclusion, we have revealed a novel mechanism of HPV oncoprotein-mediated malignant transformation. These findings might provide effective strategies for treating cervical and HPV-associated cancers.

HPV16 E6 promoting cervical cancer progression through down-regulation of miR-320a to increase TOP2A expression.

Cervical cancer (CC) has become the fourth most common cancer worldwide and it is mainly caused by the infection of human papillomavirus (HPV), especially high-risk HPV16. Aberrant miRNA expression in CC is closely related to HPV16 infection, and the regulation of HPV16 E6 expression can affect a variety of miRNA expression. This study aims to exploring the miRNAs involved in E6 regulation in CC. Our study screened differentially expressed miRNAs in cervical cells of HPV16 infected and uninfected cervical cancer patients by analyzing the GSE81137 dataset of the gene expression omnibus database (GEO), and identified miR-320a that plays an anti-tumor role and is associated with good prognosis of cervical cancer. Explore the effect of HPV16 E6 on the expression of miR-320a in cervical cancer, and verify whether HPV16 E6 regulates the downstream target gene TOP2A expression through miR-320a, thereby affecting cervical cancer cell proliferation, apoptosis, migration, invasion, and EMT invitro and invivo. The bioinformatic methods selected the miR-320a, which was differentially expressed in cervical cells from HPV16-infected patients compared to uninfected patients. We further demonstrated that miR-320a level was regulated by HPV16 E6, which promoted the CC cell proliferation, migration, invasion, and inhibited apoptosis. In addition, we predicted the downstream target genes of miR-320a and confirmed that TOP2A was one of its targeting proteins. Moreover, HPV16 E6 promoted the TOP2A expression in CC cells through down-regulating miR-320a, leading to promoting CC development. We confirmed that HPV16 E6 promoted the TOP2A expression through down-regulation of miR-320a, thus promoting CC development, and the HPV16 E6/miR-320a/TOP2A axis may perform as a potential target for CC treatment.

Differential tumor immune microenvironment coupled with tumor progression or tumor eradication in HPV-antigen expressing squamous cell carcinoma (SCC) models.

Human papilloma virus (HPV) is an etiological factor of head and neck squamous cell carcinoma (HNSCC). To investigate the role of HPV antigen in anti-tumor immunity, we established mouse models by expressing HPV16 E6 and E7 in a SCC tumor cell line. We obtained two HPV antigen-expressing clones (C-225 and C-100) transplantable into C57BL/6 recipients. We found that C-225 elicited complete eradication in C57BL/6 mice (eradicated), whereas C-100 grew progressively (growing). We examined immune tumor microenvironment (TME) using flow cytometry and found that eradicated or growing tumors exhibited differential immune profiles that may influence the outcome of anti-tumor immunity. Surprisingly, the percentage of CD8 and CD4 tumor-infiltrating lymphocytes (TILs) was much higher in growing (C-100) than eradicated (C-225) tumor. However, the TILs upregulated PD-1 and LAG-3 more potently and exhibited impaired effector functions in growing tumor compared to their counterparts in eradicated tumor. C-225 TME is highly enriched with myeloid cells, especially polymorphonuclear (PMN) myeloid-derived suppressor cells (MDSC), whereas the percentage of M-MDSC and tumor-associated macrophages (TAMs) was much higher in C-100 TME, especially M2-TAMs (CD206+). The complete eradication of C-225 depended on CD8 T cells and elicited anti-tumor memory responses upon secondary tumor challenge. We employed DNA sequencing to identify differences in the T cell receptor of peripheral blood lymphocytes pre- and post-secondary tumor challenge. Lastly, C-225 and C-100 tumor lines harbored different somatic mutations. Overall, we uncovered differential immune TME that may underlie the divergent outcomes of anti-tumor immunity by establishing two SCC tumor lines, both of which express HPV16 E6 and E7 antigens. Our experimental models may provide a platform for pinpointing tumor-intrinsic versus host-intrinsic differences in orchestrating an immunosuppressive TME in HNSCCs and for identifying new targets that render tumor cells vulnerable to immune attack.

Abstract PO-023: The AP-1 transcription factor component, JunB, regulates the expression of HPV genes in head and neck cancer

Abstract Within head and neck squamous cell carcinoma (HNSCC), those induced by the human papillomavirus (HPV+) have a more hypermethylated genome compared to those that are negative (HPV-). Therefore, our lab explored the usage of the demethylating agent 5-azacytidine (5-aza), an FDA-approved drug for the treatment of myelodysplasia and acute myeloid leukemia. Repurposing FDA-approved drugs is a strategic way to quickly provide patients with secondary therapeutic options, especially since the incidence of HPV+ HNSCC is now considered an epidemic in the US and Western Europe. Additionally, initial therapy for patients is aggressive leading to adverse, lifelong side effects. Despite having a higher cure rate than HPV-HNSCC, the recurrence rate is still approximately 30% for HPV+ HNSCC. Our lab has found that HPV+ HNSCC cells are more sensitive than HPV- cells to 5-aza as low doses of 5-aza delayed HPV+ xenograft tumor growth and 5-aza-treated HPV+ tumor samples from patients treated in a window trial had increased cell death. Despite demethylation inducing an active, open chromatin conformation, we also observed a marked downregulation of HPV genes expression after 5-aza. Decreased HPV E6 expression, followed by reactivation of tumor suppressor p53, induced p53-dependent apoptosis in HPV+ HNSCC. This decreased expression of HPV genes is an essential component of 5-aza-associated toxicity toward HPV+ HNSCC. Our lab has recently explored the molecular mechanisms of 5-aza on HPV+ HNSCC. We found that 5-aza transcriptionally downregulated the expression of HPV genes, including oncogenes E6 and E7. Microarray studies show marked downregulation of the proto-oncogene JunB, a component of the transcription factor AP-1 (Activator Protein 1) after 5-aza treatment. Experimental deletion of JunB inhibited oncogenes E6 and E7 and restored p53 but also indicated that untreated HPV+ HNSCCs depend on JunB for clonogenic growth. Through this study, we have identified a novel dependency on JunB in HPV+ HNSCC and revealed a new rational target that is desperately needed to treat recurrent/metastatic patients and decrease the toxicity associated with current treatment. Citation Format: Hina Rehmani, Natalia Isaeva, Travis P. Schrank, Wendell G. Yarbrough. The AP-1 transcription factor component, JunB, regulates the expression of HPV genes in head and neck cancer [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Innovating through Basic, Clinical, and Translational Research; 2023 Jul 7-8; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2023;29(18_Suppl):Abstract nr PO-023.

Expression of HPV-16 E6 and E7 oncoproteins alters Chlamydia trachomatis developmental cycle and induces increased levels of immune regulatory molecules.

Infection with Human Papillomavirus (HPV) is a recognized risk factor for Chlamydia trachomatis (CT) infection and vice versa. Coinfection of HPV and CT in women is a very common and usually asymptomatic finding that has been linked to increased risk of cervical cancer. It has been demonstrated that CT facilitates the entry of multiple high risk HPV genotypes, leading to damage of the mucosal barrier and interfering with immune responses and viral clearance, which ultimately favours viral persistence and malignant transformation. Although the facilitating effects elicited by CT infection on viral persistence have been reported, little is known about the consequences of HPV infection on CT development. Herein, we took advantage of a genetically modified human cervical cell line co-expressing HPV-16 major oncogenic proteins E6 and E7, as an experimental model allowing to investigate the possible effects that HPV infection would have on CT development. Our results show that CT infection of HPV-16 E6E7 expressing cells induced an upregulation of the expression of E6E7 oncoproteins and host cell inhibitory molecules PD-L1, HVEM and CD160. Additionally, smaller chlamydial inclusions and reduced infectious progeny generation was observed in E6E7 cells. Ultrastructural analysis showed that expression of E6 and E7 did not alter total bacterial counts within inclusions but resulted in increased numbers of reticulate bodies (RB) and decreased production of infectious elementary bodies (EB). Our results indicate that during CT and HPV coinfection, E6 and E7 oncoproteins impair RB to EB transition and infectious progeny generation. On the other hand, higher expression of immune inhibitory molecules and HPV-16 E6E7 are cooperatively enhanced in CT-infected cells, which would favour both oncogenesis and immunosuppression. Our findings pose important implications for clinical management of patients with HPV and CT coinfection, suggesting that screening for the mutual infection could represent an opportunity to intervene and prevent severe reproductive health outcomes, such as cervical cancer and infertility.

A replicative recombinant HPV16 E7 expression virus upregulates CD36 in C33A cells.

In past decades, the role of high-risk HPV (HR-HPV) infection in cancer pathogenesis has been extensively studied. The viral E7 protein expressed in pre-malignant cells has been identified as an ideal target for immunological intervention. However, the cultivation of HPV in vitro remains a significant challenge, as well as the lack of methods for expressing the HPV E7 protein and generating replication-competent recombinant viral particles, which posed a major obstacle to further exploration of the function and carcinogenic mechanisms of the E7 oncoprotein. Therefore, it is imperative to investigate novel methodologies to construct replication-competent recombinant viral particles that express the HPV E7 protein to facilitate the study of its function. We initiated the construction of recombinant viral particles by utilizing the ccdB-Kan forward/reverse screening system in conjunction with the Red/ExoCET recombinant system. We followed the infection of C33A cells with the obtained recombinant virus to enable the continuous expression of HPV16 E7. Afterwards, the total RNA was extracted and performed transcriptome sequencing using RNA-Seq technology to identify differentially expressed genes associated with HPV-induced oncogenicity. We successfully established replicative recombinant viral particles expressing HPV16 E7 stably and continuously. The C33A cells were infected with recombinant viral particles to achieve overexpression of the E7 protein. Subsequently, RNA-Seq analysis was conducted to assess the changes in host cell gene expression. The results revealed an upregulation of the CD36 gene, which is associated with the HPV-induced oncogenic pathways, including PI3K-Akt and p53 signaling pathway. qRT-PCR analysis further identified that the upregulation of the CD36 gene due to the expression of HPV16 E7. The successful expression of HPV16 E7 in cells demonstrates that the replicated recombinant virus retains the replication and infection abilities of Ad4, while also upregulating the CD36 gene involved in the PI3K-Akt signaling and p53 pathways, thereby promoting cell proliferation. The outcome of this study provides a novel perspective and serves as a solid foundation for further exploration of HPV-related carcinogenesis and the development of replicative HPV recombinant vaccines capable of inducing protective immunity against HPV.

Effect of Lactobacillus delbrueckii subsp. lactis on vaginal radiotherapy for gynecological cancer

The aim of this study was to evaluate the effect of Lactobacillus delbrueckii subsp. lactis (L.del) on vaginal microbiota (VM) dysbiosis and vaginal radiation injury in gynecologic cancer patients. The inhibitory effects of L.del on cervical cancer cells were also studied in vitro. Gynecologic cancer patients receiving radiotherapy were randomized into control and L.del intervention groups. The control group received radiotherapy, while the intervention group received radiotherapy and L.del intervention (1 capsule/day placed into the deep vagina from the first day of radiotherapy until the end of treatment). Vaginal swab samples were collected on the first day pre-treatment and the last day post-treatment. DNA from 54 patients was extracted and assessed by the 16S rRNA sequencing method. Radiotherapy resulted in vaginal microbiome dysbiosis characterized by increased phylogenetic diversity and increased abundance of Brevundimonas, Streptococcus and Prevotella, but a decreased abundance of Lactobacillus. Level 2 vaginal radiation injury was positively associated with the abundance of Brevundimonas and gram-negative non-fermenting bacteria. Administration of L.del attenuated the reduction of Lactobacillus while also inhibiting the abundance of Streptococcus and Prevotella, thereby ameliorating radiotherapy-related vaginal microbiota dysbiosis. CLD inhibited the in vitro proliferation of SiHa cells by altering the expression of BCL2, HPV16-E6, HPV16-E7, IL6, MAP7, BAX, Caspase-3, Caspase-9 and LTF. In conclusion, L. del application can alleviate radiation-induced vaginal dysbiosis and restore Lactobacillus dominance of the vaginal microbiome. Moreover, CLD was found to inhibit cell growth and promote the apoptosis of SiHa cells in vitro. The registration number for this clinical trial is ChiCTR1900021784.

Human papillomavirus-driven repression of NRF2 signalling confers chemo-radio sensitivity and predicts prognosis in head and neck squamous cell carcinoma

PurposeTo investigate the role of NRF2 signalling in conferring superior prognosis in patients with HPV positive (HPV+ve) head & neck squamous cell carcinomas (HNSCC) compared to HPV negative (HPV−ve) HNSCC and develop molecular markers for selection of HPV+ve HNSCC patients for treatment de-escalation trials. MethodsNRF2 activity (NRF2, KEAP1, and NRF2-transcriptional targets), p16, and p53 levels between HPV+ve HNSCC and HPV−ve HNSCC in prospective and retrospective tumor samples as well as from TCGA database were compared. Cancer cells were transfected with HPV-E6/E7 plasmid to elucidate if HPV infection represses NRF2 activity and sensitizes to chemo-radiotherapy. ResultsProspective analysis revealed a marked reduction in expression of NRF2, and its downstream genes in HPV+ve tumors compared to HPV−ve tumors. A retrospective analysis by IHC revealed significantly lower NQO1 in p16high tumors compared to p16low tumors and the NQO1 expression correlated negatively with p16 and positively with p53. Analysis of the TCGA database confirmed low constitutive NRF2 activity in HPV+ve HNSCC compared to HPV−ve HNSCC and revealed that HPV+ve HNSCC patients with ‘low NQO1’ expression showed better overall survival compared to HPV+ve HNSCC patients with ‘high NQO1’ expression. Ectopic expression of HPV-E6/E7 plasmid in various cancer cells repressed constitutive NRF2 activity, reduced total GSH, increased ROS levels, and sensitized the cancer cells to cisplatin and ionizing radiation. ConclusionLow constitutive NRF2 activity contributes to better prognosis of HPV+ve HNSCC patients. Co-expression of p16high, NQO1low, and p53low could serve as a predictive biomarker for the selection of HPV + ve HNSCC patients for de-escalation trials.

HPV-positive murine oral squamous cell carcinoma: development and characterization of a new mouse tumor model for immunological studies

BackgroundInfection with high-risk human papillomavirus (HPV) strains is one of the risk factors for the development of oral squamous cell carcinoma (OSCC). Some patients with HPV-positive OSCC have a better prognosis and respond better to various treatment modalities, including radiotherapy or immunotherapy. However, since HPV can only infect human cells, there are only a few immunocompetent mouse models available that enable immunological studies. Therefore, the aim of our study was to develop a transplantable immunocompetent mouse model of HPV-positive OSCC and characterize it in vitro and in vivo.MethodsTwo monoclonal HPV-positive OSCC mouse cell lines were established by inducing the expression of HPV-16 oncogenes E6 and E7 in the MOC1 OSCC cell line using retroviral transduction. After confirming stable expression of HPV-16 E6 and E7 with quantitative real-time PCR and immunofluorescence staining, the cell lines were further characterized in vitro using proliferation assay, wound healing assay, clonogenic assay and RNA sequencing. In addition, tumor models were characterized in vivo in C57Bl/6NCrl mice in terms of their histological properties, tumor growth kinetics, and radiosensitivity. Furthermore, immunofluorescence staining of blood vessels, hypoxic areas, proliferating cells and immune cells was performed to characterize the tumor microenvironment of all three tumor models.ResultsCharacterization of the resulting MOC1-HPV cell lines and tumor models confirmed stable expression of HPV-16 oncogenes and differences in cell morphology, in vitro migration capacity, and tumor microenvironment characteristics. Although the cell lines did not differ in their intrinsic radiosensitivity, one of the HPV-positive tumor models, MOC1-HPV K1, showed a significantly longer growth delay after irradiation with a single dose of 15 Gy compared to parental MOC1 tumors. Consistent with this, MOC1-HPV K1 tumors had a lower percentage of hypoxic tumor area and a higher percentage of proliferating cells. Characteristics of the newly developed HPV-positive OSCC tumor models correlate with the transcriptomic profile of MOC1-HPV cell lines.ConclusionsIn conclusion, we developed and characterized a novel immunocompetent mouse model of HPV-positive OSCC that exhibits increased radiosensitivity and enables studies of immune-based treatment approaches in HPV-positive OSCC.

N-Acetyl-L-Cysteine Reduces Cervical Carcinogenesis by Promoting Apoptosis.

Cervical cancer is the fourth leading cause of cancer death in women, and is one of the most common malignant tumors of the reproductive system. However, more effective treatment for cervical cancer is needed. In this study, we aim to investigate whether N-acetyl-L-cysteine (NAC) could inhibit the proliferation of human papillomavirus (HPV)-positive cells, and reduce cervical carcinogenesis. The cervical cancer cell lines SiHa, HeLa, HPV-negative cell line C33A, and the immortalized human cervical keratinocyte cells S12 were used. The protein expression was determined using Western blot assay. mRNA expression was determined using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cell proliferation was determined by Cell Counting Kit-8 assay. Cell apoptosis was evaluated using Annexin V-FITC apoptosis kits. The numbers of colonies were measured using colony-forming assay. Xenograft tumor necrosis and HPV16 E7 expression were determined using hematoxylin and eosin (H&E) staining and immunohistochemistry. Our results showed that NAC treatment at the concentration of 1.5mM significantly promoted cell apoptosis and reduced cell growth by inhibiting HPV16 E7 expression. NAC inhibited HPV16-oncoprotein-induced hypoxia-inducible factor (HIF)-1α protein expression and Akt activation invitro. Additionally, NAC suppressed tumor growth, as evidenced by the smaller tumor size in the xenograft mouse model and decreased HPV16 E7 expression in tumor tissues. Our findings demonstrate that NAC exhibits the potential to promote HPV-positive cell apoptosis, and suppress the proliferation of HPV-positive cells by inhibiting cell inhibitor of apoptosis protein 2 and HIF-1α.

Abstract LB252: HPV integration events are heterogenous, clonally selected and associated with spatially distinct transcriptomic profiles in aggressive HPV positive oropharyngeal squamous cell carcinoma

Abstract HPV positive Oropharyngeal Squamous Cell Carcinoma (HPV positive OPSCC) is rising in incidence and, for patients that recur, survival is extremely poor. Recent technological advances have led to a better understanding of patterns of HPV integration in primary tumors but have not yet tested the evolution of these events in deadly forms of the disease. Therefore, we performed multi-region sequencing analysis on a cohort of 34 recurrent and metastatic patients with HPV positive OPSCC (29% survival rate) plus one recurrent HPV positive model pair, UPCI-90 and UPCI-152. We then used our recently developed capture-based sequencing HPV integration caller and assembler pipeline, SearcHPV, to identify patterns of viral integration into the host genome and Oxford Nanopore long-read whole genome sequencing to validate the integration events in selected cases. In total, 1591 HPV integrations were called and assembled. Unexpectedly, our analysis revealed that HPV integration events are heterogenous as multiple independent integration events were observed in different spatial regions of the same tumor. Further, when comparing independent and anatomically distinct regions of recurrence from the same patient, independent integration events were also observed. Heterogeneity of integration structures was found to include variation of local HPV copy number, distribution of the specific HPV integration sites within the structures as well as distinct characteristics of rearrangement breakpoints (human-HPV, HPV-HPV, human-human). Given this observation, we then evaluated the hypothesis that HPV integration events could be clonally selected by comparing the integration profiles from a cohort of matched primary and recurrent tumors. In this cohort, 64 integration events (11 exact same; 53 clustered in the same genes) were maintained throughout tumor progression to recurrence, while other integration events were lost, supporting a model of clonal evolution with driver and passenger integrations. We then explored this further using one recurrent HPV positive model pair, UPCI-90 and UPCI-152, using long-read whole genome sequencing which validated the heterogeneity and clonal selection of HPV integration events. Finally, to test if differences in HPV integration content in spatially distinct regions could drive spatially distinct phenotypic differences, we performed multi-region RNA-seq analysis on 8 HPV16 positive OPSCCs, which demonstrated spatial differences in HPV16 E7 expression, that were validated with RNAscope assays, as well as statistically significant spatial enrichment of independent oncogenic gene sets. Collectively, we report evidence showing that HPV integration events are heterogenous, clonally selected during progression and associated with distinct transcriptomic profiles. Based on this data, we now propose a new working model of disease pathogenesis in which heterogeneity and clonal evolution of HPV integration events serve as a critical driver of the disease process. Citation Format: Wenjin Gu, Apurva Bhangale, Collin V. Brummel, Elizabeth Gensterblum-Miller, Matthew E. Spector, Ryan E. Mills, Chad Brenner. HPV integration events are heterogenous, clonally selected and associated with spatially distinct transcriptomic profiles in aggressive HPV positive oropharyngeal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB252.

Estrogen induces genomic instability in high-risk HPV-infected cervix and promotes the carcinogenesis of cervical adenocarcinoma

High-risk human papillomavirus (HPV) infection is the major cause of cervical cancer. However, the factors that modulate the process from infection to carcinogenesis are poorly understood. Although cervical cancer is clinically considered an estrogen-independent tumor, the role of estrogen in cervical cancer, particularly cervical adenocarcinoma, remains controversial. In this study, we showed that estrogen/GPR30 signaling induced genomic instability, which leads to carcinogenesis in high-risk HPV-infected endocervical columnar cell lines.The expression of estrogen receptors in a normal cervix was confirmed through immunohistochemical analysis which showed that G protein-coupled receptor 30 (GPR30) was predominantly expressed in endocervical glands and estrogen receptor-α (ERα) was expressed at higher levels in the squamous epithelium than in the cervical gland. E2 increased the proliferation of cervical cell lines, particularly normal endocervical columnar and adenocarcinoma cells via GPR30 rather than ERα, and increased the accumulation of DNA double-strand breaks (DSBs) in high-risk HPV-E6-expressing cells. The increase in DSBs was caused by the impairment of Rad 51 and accumulation of topoisomerase-2-DNA complexes under HPV-E6 expression. In addition, chromosomal aberrations increased in cells with E2-induced DSB accumulation. Collectively, we conclude that E2 exposure in high-risk HPV-infected cervical cells increases DSBs, leading to genomic instability and thus carcinogenesis via GPR30.

Abstract 1212: Horizontal transfer of functional human papillomavirus genes in head and neck squamous cell carcinoma

Abstract Human papillomavirus (HPV) infections are currently associated with more than 70% of oropharyngeal squamous cell carcinomas (OPSCCs). HPV-positive OPSCCs display a distinct biologic behavior and treatment response and thus are now considered a distinct entity than HPV-negative OPSCCs. However, the underlying process of HPV-related OPSCC carcinogenesis is not entirely clear. HPV as a driver of cervical carcinogenesis is well-characterized with identification of a canonical mechanism dependent on HPV DNA integration, loss of HPV E2 gene expression, and increased expression of HPV E6 and E7 oncogenes with no active infection present in malignant lesions. However, whole genome sequencing found no HPV DNA integration in ~25% of HPV-associated OPSCC, suggesting an alternative mechanism of HPV carcinogenesis. Expression of all HPV genes, including self-assembling capsid proteins, in a substantial portion of HPV+ OPSCC, led us to hypothesize that tumors with episomal HPV are capable of transferring HPV genes to surrounding cells and that HPV gene transfer contributes to carcinogenesis in this subset of OPSCC. Our data support this hypothesis, showing that growth media from HPV+ OPSCC cell lines, as well as isolates from HPV+ tumors or nodal metastases, effectively transferred functional HPV genes to cells lacking HPV. The HPV DNA Transferring Agent (HDTA) derived from HPV+ OPSCC contained HPV L1 capsid protein and intact HPV genome protected from DNAase degradation. Initial characterization revealed that anti-L1 antibody blocked gene transfer and that exposure of cells to the HDTA initiated a robust innate immune response in recipient cells. Negative staining of HDTA isolate from metastatic lymph nodes revealed many pleomorphic, electron-dense particles with diameter ranging between 20 and 80nM, with approximately 40% of particles being between 50 and 60nM, consistent with the size of HPV. We propose that development and/or maintenance of OPSCCs depend on continuous production of HDTA capable of transferring HPV genes into neighboring cells. This paradigm of tumorigenesis/maintenance in OPSCC is most likely to apply to cancers lacking HPV integration, but may also apply to tumors with integration, since recent data suggested that integrated HPV may excise from the genome to recreate a transient episomal like structure, even containing cellular DNA. Our findings offer novel insights into oropharyngeal carcinogenesis and suggest targeting HDTA as a new therapeutic strategy for HPV-positive OPSCCs. Citation Format: Jason Tasoulas, Wendell Gray Yarbrough, Natalia Issaeva. Horizontal transfer of functional human papillomavirus genes in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1212.

Abstract 3925: JunB regulates expression of HPV genes in head and neck cancer

Abstract The incidence of HPV-positive head and neck squamous cell carcinoma (HNSCC) is now being considered an epidemic in the US and Western Europe as rates have surpassed those for cervical cancer. For approximately 14,400 patients per year in the US, initial therapy is aggressive and often results in adverse lifelong side effects such as difficulty swallowing and speaking. Despite having a higher cure rate than HPV-negative HNSCC, the recurrence rate is still approximately 30%. Therefore, new treatment options need to be available for these relapsed patients. Our lab was prompted to explore demethylation as a therapeutic option as HPV-positive HNSCC have a more hypermethylated genome than HPV-negative cancers. 5-azacytidine (5-aza) is a synthetic cytidine analog that causes DNA demethylation by trapping methyltransferases to chromatin; it is FDA-approved for the treatment of myelodysplasia and acute myeloid leukemia. Our lab found that low doses of 5-aza delayed HPV-positive xenograft tumor growth and that HPV-positive tumor samples from patients treated with 5-aza in a window trial had increased apoptosis. They also observed a marked downregulation of HPV gene expression after 5-aza. Decreased HPV E6 expression, followed by reactivation of tumor suppressor p53, induced p53-dependent apoptosis in HPV-positive HNSCC. To further explore the mechanism of this sensitivity to 5-Aza, we first determined that 5-aza regulates the transcription of HPV genes, but not the stability of HPV transcripts. We found that the transcriptional regulation of HPV genes after 5-aza depends on the proto-oncogene JunB, a component of the transcription factor Activator Protein 1 (AP-1). Additionally, silencing of JunB abolished the expression of HPV E6/E7 genes and reactivated tumor suppressor p53 in HPV-positive HNSCC. Furthermore, we revealed that clonogenic survival of HPV-positive head and neck cancer cells is dependent on JunB expression. Our study exposes an important component of 5-Aza-associated sensitivity and toxicity in HPV-positive HNSCC and identifies a novel dependency on JunB, potentially providing a new rational targeted therapy. Citation Format: Hina Rehmani, Travis P. Schrank, Natalia Issaeva, Wendell G. Yarbrough. JunB regulates expression of HPV genes in head and neck cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3925.

HPV16 E6 induces chromosomal instability due to polar chromosomes caused by E6AP-dependent degradation of the mitotic kinesin CENP-E

Chromosome segregation during mitosis is highly regulated to ensure production of genetically identical progeny. Recurrent mitotic errors cause chromosomal instability (CIN), a hallmark of tumors. The E6 and E7 oncoproteins of high-risk human papillomavirus (HPV), which causes cervical, anal, and head and neck cancers (HNC), cause mitotic defects consistent with CIN in models of anogenital cancers, but this has not been studied in the context of HNC. Here, we show that HPV16 induces a specific type of CIN in patient HNC tumors, patient-derived xenografts, and cell lines, which is due to defects in chromosome congression. These defects are specifically induced by the HPV16 oncogene E6 rather than E7. We show that HPV16 E6 expression causes degradation of the mitotic kinesin CENP-E, whose depletion produces chromosomes that are chronically misaligned near spindle poles (polar chromosomes) and fail to congress. Though the canonical oncogenic role of E6 is the degradation of the tumor suppressor p53, CENP-E degradation and polar chromosomes occur independently of p53. Instead, E6 directs CENP-E degradation in a proteasome-dependent manner via the E6-associated ubiquitin protein ligase E6AP/UBE3A. This study reveals a mechanism by which HPV induces CIN, which may impact HPV-mediated tumor initiation, progression, and therapeutic response.

Human Papillomavirus E7 and p16INK4a mRNA Multiplexed Quantification by a QuantiGeneTM Proof-of-Concept Assay Sensitively Detects Infection and Cervical Dysplasia Severity.

Persistent infection with human papillomavirus (HPV) can lead to cervical cancer (CxCa). During the progression to CxCa, the expression of HPV oncogenes E6 and E7 is upregulated. In turn, cellular proteins such as p16INK4a are also modulated. The combined detection of HPV oncogenes and cellular biomarkers indicative for dysplasia could be informative and convey better specificity than the current HPV tests that cannot discriminate transient infection from dysplastic changes. The QuantiGeneTM 2.0 Plex Assay platform was chosen for the effective multiplexing and quantitative detection of seven HPV-E7 mRNA targets (HPV6, 16, 18, 31, 45, 59, and 68) and the cellular mRNA of p16INK4a as a biomarker for HPV-induced transformation. Actin-beta (ACTB) and hypoxanthine-guanine phosphoribosyltransferase 1 (HPRT1) were included as reference markers. Sequences for the specific capture and detector probes were customized and developed by ThermoFisher and formulated as a QuantiGene proof-of-concept (QG-POC) plex-set. The crude lysates of the HPV-positive cervical cancer cell lines CaSki (HPV16), HeLa (HPV18), MRHI-215 (HPV45), Erin59 (HPV59), ME180 (HPV68), and the HPV-negative cell line C33A, as well as liquid-based cytology smear samples (n = 441) were analyzed. The study was a proof-of-concept evaluating the feasibility of the platform. Logistic regression and receiver operating characteristic (ROC) analyses were performed to test for the sensitivity and specificity of HPV detection and dysplastic stage discrimination. A QG-POC assay specifically and sensitively detects the HPV-E7 mRNA of seven different genotypes with an assay linearity between 20 and 13,000 cells. Cellular mRNA was detected from the crude lysates of cell lines and of cellular material from clinical liquid-based cytology smear samples. By combining HPV-E7 and p16INK4a expression normalized to ACTB, high-grade dysplasia (HCIN) and invasive cervical cancer (CxCa) were detectable, discriminable, and correlated to the biomarker expression strength. The ROC analysis from the multivariate logistic regression model including HPV-E7 and p16 INK4a resulted in an AUC of 0.74, at the optimal cut-off (sensitivity: 70.4%; specificity: 66.0%) for HCIN detection. CxCa was detected with an AUC of 0.77 (sensitivity: 81.8%, specificity: 77.4%). The QG-POC assay is sufficiently sensitive to detect and quantify HPV-E7 and cellular mRNA species. Multiplexing allows the specific detection of at least 10 analytes in a single reaction. Determining the abundance of E7 and p16INK4a transcripts when normalized to ACTB is informative about the presence of cervical dysplasia and potentially discriminates between low-grade and high-grade dysplasia and invasive cervical cancer. Further studies including more HPV genotypes and biomarkers are warranted.

HPV upregulates MARCHF8 ubiquitin ligase and inhibits apoptosis by degrading the death receptors in head and neck cancer.

The membrane-associated RING-CH-type finger ubiquitin ligase MARCHF8 is a human homolog of the viral ubiquitin ligases Kaposi's sarcoma herpesvirus K3 and K5 that promote host immune evasion. Previous studies have shown that MARCHF8 ubiquitinates several immune receptors, such as the major histocompatibility complex II and CD86. While human papillomavirus (HPV) does not encode any ubiquitin ligase, the viral oncoproteins E6 and E7 are known to regulate host ubiquitin ligases. Here, we report that MARCHF8 expression is upregulated in HPV-positive head and neck cancer (HNC) patients but not in HPV-negative HNC patients compared to normal individuals. The MARCHF8 promoter is highly activated by HPV oncoprotein E6-induced MYC/MAX transcriptional activation. The knockdown of MARCHF8 expression in human HPV-positive HNC cells restores cell surface expression of the tumor necrosis factor receptor superfamily (TNFRSF) death receptors, FAS, TRAIL-R1, and TRAIL-R2, and enhances apoptosis. MARCHF8 protein directly interacts with and ubiquitinates the TNFRSF death receptors. Further, MARCHF8 knockout in mouse oral cancer cells expressing HPV16 E6 and E7 augments cancer cell apoptosis and suppresses tumor growth in vivo. Our findings suggest that HPV inhibits host cell apoptosis by upregulating MARCHF8 and degrading TNFRSF death receptors in HPV-positive HNC cells.