HPV16 E7 Research Articles

Characteristics of Cervical Cancer Caused by the Human Papillomavirus 18 and Its Genetic Variations in Vietnamese Women

BackgroundThe involvement of HPV18 in cervical cancer pathogenesis, as well as its high oncogenic potential and influence on the variation of cervical cancer distribution in different geographical regions, makes assessing the characteristics of cervical cancer and its variants the basis for considering potential carcinogenic HPV18 sequence variations and vaccine strategies. MethodsA prospective study was conducted at Vietnam Central Obstetrics Hospital from January 1, 2019 to December 31, 2020. HPV18 infection was confirmed in cervical cancer patients using molecular diagnostics. Nucleotide sequences of the HPV18 E6, E7, and L1 genes were used to analyze genetic variations. The demographic, clinical, and laboratory data of the patients were collected and statistically analyzed. ResultsAmong 48 patients with HPV18-infected cervical cancer, 79.2% were between the ages of 35–54; while only 20.8% were < 35 and > 54 years old. 100% of patients have been pregnant at some point in their lives, with ≥3 pregnancies accounting for 83.3%. Patients with cervical cancer caused by HPV18 infection were predominantly in stages 0 and I, with no patients in stages II, III, or IV. A single HPV18 infection generates much more cervical cancer cases than multiple HPV18 infections. Symptoms such as lower abdomen pain, unusual anginal discharge, and vaginal bleeding were observed in both stages 0 and I; however, vaginal bleeding after sex was only detected in women with stage I cervical cancer. Cervicitis, cervical ectropion, and ulcers are reported in cervical status stages 0 and I; however, warts and ulcers were only present in stage I. Magnetic resonance imaging produces far superior outcomes than ultrasound. All cytology and pathology tests confirmed L/HSIL, SCC, AC, and CIS. On the other hand, a single HPV18 infection was associated with a significantly higher risk of L/HSIL, SCC, AC, and CIS than multiple HPV18 infections. Nulceotide sequences of the E6, E7, and L1 genes revealed 20 mutations, including three (E6), five (E7), and twelve (L1) mutations. High-frequency mutations (95.8%–100% of HPV18 samples had mutations) occur at the following positions: C287G - P61P (E6 gene), G5503A - R25Q, C5701G - P91R, C6460G - P344R, C6625G - P399R, and C6842G - P471R (L1 gene). A phylogenetic tree based on the E6/E7/L1 gene sequence revealed that 100% belonged to A lineage, with 97.9% belonging AA (Asian Amerindian - A1) and 2.1% belonging to the E (European - A5). ConclusionPatients with a single HPV18 infection have a higher risk of cervical cancer than those infected with HPV18 and other high-risk strains simultaneously. HPV18 single-infection, on the other hand, had considerably higher incidences of L/HSIL, SCC, AC, and CIS than HPV18 co-infection. The HPV18 strain that was found in Vietnam belonged to lineage A (A1 and A5), which contains several oncogene mutations.

Oncoproteins E6 and E7 upregulate topoisomerase I to activate the cGAS-PD-L1 pathway in cervical cancer development.

Background: Cervical cancer (CC) stands as a significant health threat to women globally, with high-risk human papillomaviruses as major etiologic agents. The DNA damage repair (DDR) protein topoisomerase I (TOP1) has been linked to various cancers, yet its distinct roles and mechanisms in CC are not fully elucidated. Methods: We investigated TOP1 expression in cervical intraepithelial neoplasia (CIN) and CC tissues utilizing qRT-PCR and IHC, correlating findings with patient prognosis. Subsequent knockdown studies were performed in vitro and in vivo to evaluate the influence of TOP1 on tumor growth, DNA repair, and inflammatory responses. Results: TOP1 was highly expressed in CIN and CC, negatively correlating with patient prognosis. Inhibition of TOP1 impeded CC cell growth and disrupted DNA repair. TOP1 was shown to regulate tumor-promoting inflammation and programmed death-ligand 1 (PD-L1) production in a cGAS-dependent manner. HPV oncoproteins E6 and E7 upregulated TOP1 and activated the cGAS-PD-L1 pathway. Conclusions: TOP1 acts as a DNA repair mediator, promoting CC development and immune evasion. Targeting the TOP1-cGAS-PD-L1 axis could be a potential therapeutic strategy for CC.

Salmonella immunotherapy engineered with highly efficient tumor antigen coating establishes antigen-specific CD8+ T cell immunity and increases in antitumor efficacy with type I interferon combination therapy

ABSTRACT Bacteria-based cancer therapy employs various strategies to combat tumors, one of which is delivering tumor-associated antigen (TAA) to generate specific immunity. Here, we utilized a poly-arginine extended HPV E7 antigen (9RE7) for attachment on Salmonella SL7207 outer membrane to synthesize the bacterial vaccine Salmonella-9RE7 (Sal-9RE7), which yielded a significant improvement in the amount of antigen presentation compared to the previous lysine-extended antigen coating strategy. In TC-1 tumor mouse models, Sal-9RE7 monotherapy decreased tumor growth by inducing E7 antigen-specific immunity. In addition, pairing Sal-9RE7 with adjuvant Albumin-IFNβ (Alb-IFNβ), a protein cytokine fusion, the combination significantly increased the antitumor efficacy and enhanced immunogenicity in the tumor microenvironment (TME). Our study made a significant contribution to personalized bacterial immunotherapy via TAA delivery and demonstrated the advantage of combination therapy.

Detection of serum biomarkers of HPV-16 driven oropharynx and oral cavity cancer in Brazil

BackgroundHPV-16 driven oropharynx/oral cavity squamous cell carcinomas prevalence varies globally. We evaluated the presence of HPV-16 ctDNA and HPV-16 E6 antibodies in samples obtained from participants treated at the Instituto do Cancer do Estado de Sao Paulo, ICESP, and from whom tumoral HPV DNA, HPV-16 E6*I mRNA, and p16INK4a status was also accessed. MethodsHPV was genotyped by PCR-hybridization. All HPV DNA positive and ∼10 % HPV DNA negative cases underwent p16INK4a immunohistochemistry and E6*I RNA testing using a multiplex bead based protocol. HPV-16 ctDNA and anti-E6 antibodies were assessed by ddPCR (digital droplet PCR) and multiplex serology, respectively. ResultsThe prevalence of HPV-16 in oropharynx carcinoma (OPC) cases was low (8.7 %) when considering solely HPV-16 DNA detection, and even lower (5.2 %) when taken into consideration the concomitant detection of HPV-16 E6*I RNA and/or p16INK4 (HPV-16 attributable fraction - AF). None of the oral cavity cancer (OCC) cases were detected with HPV-16 DNA. HPV-16 ctDNA was more commonly detected than HPV-16 E6 antibodies (29.8 % versus 10.6 %). Both serum biomarkers attained 100 % sensitivity of detecting HPV-16 AF OPC, however the specificity of the HPV-16 anti-E6 biomarker was higher compared to ctDNA (93.2 % versus 75.0 %). Finally, when both HPV-16 ctDNA and anti-E6 biomarkers were considered together, the sensitivity and specificity for HPV-16 OPC detection was 100 % and about 70 %, respectively, independently of analyzing HPV-16 DNA positive or HPV-16 AF tumors. ConclusionsOur findings corroborate that serum biomarkers are highly sensitive and specific biomarkers for detection of HPV-associated OPC.

Preferential Expansion of HPV16 E1-Specific T Cells from Healthy Donors' PBMCs after Ex Vivo Immunization with an E1E2E6E7 Fusion Antigen.

Persistent human papillomavirus (HPV) infection is responsible for practically all cervical and a high proportion of anogenital and oropharyngeal cancers. Therapeutic HPV vaccines in clinical development show great promise in improving outcomes for patients who mount an anti-HPV T-cell response; however, far from all patients elicit a sufficient immunological response. This demonstrates a translational gap between animal models and human patients. Here, we investigated the potential of a new assay consisting of co-culturing vaccine-transduced dendritic cells (DCs) with syngeneic, healthy, human peripheral blood mononuclear cells (PBMCs) to mimic a human in vivo immunization. This new promising human ex vivo PBMC assay was evaluated using an innovative therapeutic adenovirus (Adv)-based HPV vaccine encoding the E1, E2, E6, and E7 HPV16 genes. This new method allowed us to show that vaccine-transduced DCs yielded functional effector T cells and unveiled information on immunohierarchy, showing E1-specific T-cell immunodominance over time. We suggest that this assay can be a valuable translational tool to complement the known animal models, not only for HPV therapeutic vaccines, and supports the use of E1 as an immunotherapeutic target. Nevertheless, the findings reported here need to be validated in a larger number of donors and preferably in patient samples.

In vitro activity of various Kenyan tea extracts against HeLa human cervical cancer cell line and molecular docking of tea catechins on high-risk HPV16E6 protein

Tea (Camellia sinensis) has been revealed to possess potential anticancer properties attributed to its catechin content. This study aimed to investigate the growth-inhibitory effects of various tea extracts on the HeLa cell line and molecular docking analysis of catechins on Human papillomavirus16 oncoprotein 6 (HPV16E6). Different catechins content in black, green, and purple tea were determined by using High-performance liquid chromatography (HPLC); molecular docking of four main catechins on HPV16E6 and in vitro antiproliferative activity and cell apoptosis assay were carried out. Molecular docking results suggested that the tea catechins have the potential to bind to the HPV16 E6 oncoprotein involved in cervical cancer development. The antiproliferative assay results indicated that purple tea had the highest inhibitory activity at both 24 h and 48 h, with IC50 values of 121.1 ± 3.25 μg/mL and 100.1 ± 3.76 μg/mL respectively, followed by green tea with 168.9 ± 12.59 μg/mL and 124.7 ± 3.53 μg/mL IC50 while black tea showed the least effectiveness with IC50 of 221 ± 19.35 μg/mL and 159.6 ± 2.33 μg/mL. DNA fragmentation, a characteristic of apoptosis, was observed in cells treated with the tea extracts. All three tea extracts demonstrated potential anti-cervical cancer activity bIy inhibiting cell proliferation and inducing apoptosis. The tea catechins showed promising interactions with the HPV16 E6 oncoprotein.

Abstract A003: High-throughput TCR sequencing demonstrates induction of long-lasting HPV16-specific T cell responses in VB10.16 vaccinated advanced cervical cancer patients

Abstract Background: Assessment of vaccine-induced T cell responses is a primary pharmacodynamic readout in cancer vaccine clinical trials. High-throughput sequencing of T cell receptors (TCRs) is emerging as a rapid and scalable method, suitable for late-stage clinical trials, and offers sensitive and accurate quantification of the full T cell repertoire. Here we performed ELISpot and TCR sequencing on serial peripheral blood mononuclear cell (PBMC) samples from a clinical phase 2 trial investigating the therapeutic HPV16 cancer vaccine VB10.16 in combination with atezolizumab in advanced cervical cancer patients (NCT04405349). Methods: T cell responses were assessed by ex vivo IFN-g ELISpot (n=36). Immunosequencing of the TCRB locus was performed in 10 patients with available PBMCs, representing clinical response, stable disease, and progressive disease as best overall response. Immunosequencing of PBMC-derived gDNA was performed on up to five timepoints per patient, ranging from week 10 to 52. Novel and expanded clones from baseline to on-treatment timepoints were determined by a differential abundance framework, using binomial models in pair-wise comparisons, enabling longitudinal tracking of significantly expanded T cell clones. The sequences were matched and annotated to HPV16-specific TCRs present in a proprietary database of confirmed HLA class I HPV16-specific T cell clones; the database was constructed from querying the T cell repertoires of 92 healthy donors with 146 peptides derived from HPV16 E6 and E7 in MIRA assay. Results: An increased T cell response was significantly associated with disease control assessed by RECIST1.1 (n=24 patients with disease control vs n=12 patients with progressive disease, p=0.0113) and patients with a &amp;gt;2-fold increase measured by ex vivo IFN-g ELISpot showed a numerically improved progression-free survival (8 vs 3.7 months median PFS). The longitudinal tracking of TCRs provided a detailed insight into the dynamics of the overall TCR repertoire during treatment. Expansion of both pre-existing and newly expanded T cell clones was observed from week 10 and persisted until the end of treatment. Despite the non-exhaustive database, at least one verified HPV16-specific CD8 T cell clone was expanded in 8 out of 10 patients, supporting that the clonotypic expansion is caused by VB10.16. In 5 out of 7 patients with disease control, the breadth of HPV16-specific TCRs increased after vaccination, demonstrating induction of clinically relevant T cell responses. Conclusions: We demonstrate induction of strong and long-lasting HPV16-specific T cell responses after treatment with VB10.16 and atezolizumab in advanced cervical cancer patients. Induction of HPV16-specific T cell responses was significantly correlated with clinical efficacy. Immunosequencing and HPV16-specific annotation allowed longitudinal tracking of expanded TCRs and demonstrated a potential clinical relevance of increased repertoire diversity of HPV16-specific CD8 T cells in patients. Citation Format: Kaja C G Berg, Paula Bousquet, Milena Blaga, Thomas Bello, Mohammad Arabpour, Mikkel W Pedersen, Karoline Schjetne. High-throughput TCR sequencing demonstrates induction of long-lasting HPV16-specific T cell responses in VB10.16 vaccinated advanced cervical cancer patients [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A003.

HPV16 E6/E7-mediated regulation of PiwiL1 expression induces tumorigenesis in cervical cancer cells.

PiwiL1 has been reported to be over-expressed in many cancers. However, the molecular mechanism by which these proteins contribute to tumorigenesis and their regulation in cancer cells is still unclear. We intend to understand the role of PiwiL1 in tumorigenesis and also its regulation in cervical cells. We studied the effect of loss of PiwiL1 function on tumor properties of cervical cancer cells in vitro and in vivo. Also we have looked into the effect of PiwiL1 overexpression in the malignant transformation of normal cells both in vitro and in vivo. Further RNA-seq and RIP-seq analyses were done to get insight of the direct and indirect targets of PiwiL1 in the cervical cancer cells. Here, we report that PiwiL1 is not only over-expressed, but also play a major role in tumor induction and progression. Abolition of PiwiL1 in CaSki cells led to a decrease in the tumor-associated properties, whereas, its upregulation conferred malignant transformation of normal HaCaT cells. Our study delineates a new link between HPV oncogenes, E6 and E7 with PiwiL1. p53 and E2F1 directly bind and differentially regulate PiwiL1 promoter in a context-dependant manner. Further, RNA-seq together with RIP-RNA-seq suggested a strong and direct role for PiwiL1 in promoting metastasis in cervical cancer cells. Our study demonstrates that PiwiL1 act as an oncogene in cervical cancer by inducing tumor-associated properties and EMT pathway. The finding that HPV oncogenes, E6/E7 can positively regulate PiwiL1 suggests a possible mechanism behind HPV-mediated tumorigenesis in cervical cancer.

Mangostenone Bioactive Compound from Garcinia mangostana L. as Antiviral Agent via Dual Inhibitors Against E6 HPV 16/18 Oncoprotein through Computational Simulation

HPV is a DNA virus from Papillomaviridae about 170 types have been identified and most of these viruses can triger cervial cancer disease. Types of HPV that can trigger cervical cancer consist of HPV-16 and HPV-18 with around 70% of cases, HPV-6 and HPV-11 only trigger genital warts. Types of HPV-16 and HPV-18 are high risk in triggering cervical cancer. High risk HPV types have the ability to interfere with the performance of tumor suppressors in cells through oncoprotein activity. E6 is a crucial oncoprotein because it allows degradation of tumor suppressors in host cells, E6 can be a major target in antiviral drug design. Inhibition of the E6 domain by antiviral candidate compounds is an important part of preventing the formation of the E6-p53 complex and preventing cancer development. Garcinia mangostana L. (Mangosteen) is a traditional medicine for treating bacterial, viral, fungal infections, as an antioxidant, and for degenerative diseases. This study aims to explore the potential of mangostenone compounds from Garcinia mangostana L. as HPV antivirals through inhibition of the E6 oncoprotein on HPV-16 and HPV-18 through in silico study. In silico analysis methods such as drug likeness, antiviral probability, docking simulation, chemical interaction analysis, and molecular visualization were used in this study to reveal HPV antiviral candidates from Mangostenone derivatives. Mangostenone derivative compounds from Garcinia mangostana L. can be antiviral candidates for HPV through a dual inhibitory mechanism by Mangostenone A. These compounds have strong activity through more negative binding affinity values and weak bonds such as hydrogen and hydrophobic bonds compared to other mangostenone derivative compounds.

γδ T cell-mediated cytotoxicity against patient-derived healthy and cancer cervical organoids.

Cervical cancer is a leading cause of death among women globally, primarily driven by high-risk papillomaviruses. However, the effectiveness of chemotherapy is limited, underscoring the potential of personalized immunotherapies. Patient-derived organoids, which possess cellular heterogeneity, proper epithelial architecture and functionality, and long-term propagation capabilities offer a promising platform for developing viable strategies. In addition to αβ T cells and natural killer (NK) cells, γδ T cells represent an immune cell population with significant therapeutic potential against both hematologic and solid tumours. To evaluate the efficacy of γδ T cells in cervical cancer treatment, we generated patient-derived healthy and cancer ectocervical organoids. Furthermore, we examined transformed healthy organoids, expressing HPV16 oncogenes E6 and E7. We analysed the effector function of in vitro expanded γδ T cells upon co-culture with organoids. Our findings demonstrated that healthy cervical organoids were less susceptible to γδ T cell-mediated cytotoxicity compared to HPV-transformed organoids and cancerous organoids. To identify the underlying pathways involved in this observed cytotoxicity, we performed bulk-RNA sequencing on the organoid lines, revealing differences in DNA-damage and cell cycle checkpoint pathways, as well as transcription of potential γδ T cell ligands. We validated these results using immunoblotting and flow cytometry. We also demonstrated the involvement of BTN3A1 and BTN2A1, crucial molecules for γδ T cell activation, as well as differential expression of PDL1/CD274 in cancer, E6/E7+ and healthy organoids. Interestingly, we observed a significant reduction in cytotoxicity upon blocking MSH2, a protein involved in DNA mismatch-repair. In summary, we established a co-culture system of γδ T cells with cervical cancer organoids, providing a novel in vitro model to optimize innovative patient-specific immunotherapies for cervical cancer.

A novel HPV16 splicing enhancer critical for viral oncogene expression and cell immortalization.

High-risk carcinogenic human papillomaviruses (HPVs), e.g. HPV16, express the E6 and E7 oncogenes from two mRNAs that are generated in a mutually exclusive manner by splicing. The HPV16 E7 mRNA, also known as the E6*I/E7 mRNA, is produced by splicing between splice sites SD226 and SA409, while E6 mRNAs retain the intron between these splice sites. We show that splicing between HPV16 splice sites SD226 and SA409 is controlled by a splicing enhancer consisting of a perfect repeat of an adenosine-rich, 11 nucleotide sequence: AAAAGCAAAGA. Two nucleotide substitutions in both 11 nucleotide sequences specifically inhibited production of the spliced E6*I/E7 mRNA. As a result, production of E7 protein was reduced and the ability of HPV16 to immortalize human primary keratinocytes was abolished. The splicing-enhancing effect was mediated by the cellular TRAP150/THRAP3 protein that also enhanced splicing of other high-risk HPV E6*I/E7 mRNAs, but had no effect on low-risk HPV mRNAs. In summary, we have identified a novel splicing enhancer in the E6 coding region that is specific for high-risk HPVs and that is critically linked to HPV16 carcinogenic properties.

Human papillomavirus type 16 E6 promotes cervical cancer proliferation by upregulating transketolase enzymatic activity through the activation of protein kinase B.

Over 99% of precancerous cervical lesions are associated with human papillomavirus (HPV) infection, with HPV types 16 and 18 (especially type 16) found in over 70% of cervical cancer cases globally. E6, a critical HPV gene, triggers malignant proliferation by degrading p53; however, this mechanism alone cannot fully explain the oncogenic effects of HPV16 E6. Therefore, we aimed to investigate new targets of HPV oncogenic mechanisms. Our results revealed significant changes in nonoxidative pentose phosphate pathway (PPP) metabolites in HPV16-positive cells. However, the role of nonoxidative PPP in HPV-associated cell transformation and tumor development remained unexplored. In this study, we investigated the impact and mechanisms of HPV16 E6 on cervical cancer proliferation using the HPV-negative cervical cancer cell line (C33A). HPV16 E6 was found to promote cervical cancer cell proliferation both in vitro and in vivo, activating the nonoxidative PPP. Transketolase (TKT), a key enzyme in the nonoxidative PPP, is highly expressed in cervical cancer tissues and associated with poor prognosis. HPV16 E6 promotes cervical cancer cell proliferation by upregulating TKT activity through the activation of AKT. In addition, oxythiamine (OT), a TKT inhibitor, hindered tumor growth, with enhanced effects when combined with cisplatin (DDP). In conclusion, HPV16 E6 promotes cervical cancer proliferation by upregulating TKT activity through the activation of AKT. OT demonstrates the potential to inhibit HPV16-positive cervical cancer growth, and when combined with DDP, could further enhance the tumor-suppressive effect of DDP.

Decoding the Genetic and Structural Features of HPV16 E5 Oncogene in Cervical Cancer Isolates from Pakistan: A Pilot Study.

Many anogenital cancers are caused by high-risk HPV. The most common subtype is HPV16, which is prevalent in the world, including Pakistan. Various amino acid residues in HPV16 E5 are associated with high cell cycle progression and proliferation. Lack of studies on HPV16E5 in Pakistan prompted the current study. This is the first report on the occurrence of pathogenic E5 variant of HPV16 in tissue sections obtained from invasive cervical cancerous patients in Pakistan. A subset of 11 samples from HPV-positive biopsies were subjected to E5 gene amplification using PCR and analyzed using bioinformatics programs. The bioinformatics analysis detected mutations causing structural variations, which potentially contribute to the oncogenic properties of proteins. The two-point mutations, C3979A and G4042A, observed in isolate 11 caused the substitution of isoleucine for leucine and valine at positions 44 and 65 in E5 protein. The rest of the isolates had Leu44Val65 amino acids. Intratypic variations and phylogenetic analysis revealed that the majority of the isolates were closely clustered with European-Asian lineage. Moreover, C3979A and G4042A contributed to higher degree of interactions with host receptors, i.e. EGFR. This is the first study reporting HPV16 variants in a Pakistani population based on variations in the E5 region. Our findings indicate that isolate 11 has a strong interaction with the intracellular domain of EGFR, which may enhance the generation of downstream signals. Since this was a pilot study to explore E5 gene mutation, future studies with large samples are absolutely needed.

The combined HPV16-E2/E6/E7 T cell response in oropharyngeal cancer predicts superior survival

Tumor-infiltrating HPV16-E2-specific CD8+ Tcells have been detected in HPV16-induced oropharyngeal squamous cell carcinoma (OPSCC). Whether intratumoral CD4+ Tcells target HPV16 E2 and if HPV16-E2-specific immunity contributes to better clinical outcome is unknown. In a prospective HPV16+ OPSCC cohort, we regularly detect HPV16-E2-specific CD4+ and CD8+ intratumoral Tcells, albeit at lower frequencies than the co-infiltrating HPV16-E6/E7-specific Tcells. These HPV16-reactive Tcells produce multiple cytokines when activated, indicating their polyfunctionality. Importantly, their combined intratumoral presence predicts superior survival, emphasizing the value of HPV16-E2-specific Tcells in anti-tumor immunity and suggests its use as a target antigen for immunotherapy.

A Therapeutic DNA Vaccine Targeting HPV16 E7 in Combination with Anti-PD-1/PD-L1 Enhanced Tumor Regression and Cytotoxic Immune Responses.

Persistent infection of high-risk human papillomavirus (HPV) and the expression of E6 and E7 oncoproteins are the main causes of cervical cancer. Several prophylactic HPV vaccines are used in the clinic, but these vaccines have limited efficacy in patients already infected with HPV. Since HPV E7 is vital for tumor-specific immunity, developing a vaccine against HPV E7 is an attractive strategy for cervical cancer treatment. Here, we constructed an HPV16 E7 mutant that loses the ability to bind pRb while still eliciting a robust immune response. In order to build a therapeutic DNA vaccine, the E7 mutant was packaged in an adenovirus vector (Ad-E7) for efficient expression and enhanced immunogenicity of the vaccine. Our results showed that the Ad-E7 vaccine effectively inhibited tumor growth and increased the proportion of interferon-gamma (IFN-γ)-secreting CD8+ T cells in the spleen, and tumor-infiltrating lymphocytes in a mouse cervical cancer model was achieved by injecting with HPV16-E6/E7-expressing TC-1 cells subcutaneously. Combining the Ad-E7 vaccine with the PD-1/PD-L1 antibody blockade significantly improved the control of TC-1 tumors. Combination therapy elicited stronger cytotoxic T lymphocyte (CTL) responses, and IFN-γ secretion downregulated the proportion of Tregs and MDSCs significantly. The expressions of cancer-promoting factors, such as TNF-α, were also significantly down-regulated in the case of combination therapy. In addition, combination therapy inhibited the number of capillaries in tumor tissues and increased the thickness of the tumor capsule. Thus, Ad-E7 vaccination, in combination with an immune checkpoint blockade, may benefit patients with HPV16-associated cervical cancer.

HPV16 E7 protein antagonizes TNF-α-induced apoptosis of cervical cancer cells via Daxx/JNK pathway

Human papillomavirus (HPV) E7 protein as an important viral factor was involved in the progression of cervical cancer by mediating the cellular signaling pathways. Daxx (Death domain-associated protein) can interact with a variety of proteins to affect the viral infection process. However, the interaction and its related function between HPV16 E7 and Daxx have not been adequately investigated. Here, it was found that HPV16 E7 can interact with Daxx in HeLa or C33A cells by co-immunoprecipitation. HPV16 E7 protein treatment can up-regulate Daxx protein expression, while the interference in Daxx expression and the agonists for JNK can both reduce the antagonistic effects of HPV16 E7 on TNF-α-induced apoptosis, suggesting that Daxx/JNK pathway may be involved in the anti-apoptotic activity of HPV16 E7.

Immune responses, therapeutic anti-tumor effects, and tolerability upon therapeutic HPV16/18 E6/E7 DNA vaccination via needle-free biojector.

Respectively, HPV16 and HPV18 cause 50% and 20% of cervical cancer cases globally. Viral proteins E6 and E7 are obligate drivers of oncogenic transformation. We recently developed a candidate therapeutic DNA vaccine, pBI-11, that targets HPV16 and HPV18 E6 and E7. Single-site intramuscular delivery of pBI-11 via a needle elicited therapeutic anti-tumor effects in mice and is now being tested in high-risk human papillomavirus+ head and neck cancer patients (NCT05799144). Needle-free biojectors such as the Tropis device show promise due to ease of administration, high patient acceptability, and the possibility of improved delivery. For example, vaccination of patients with the ZyCoV-D DNA vaccine using the Tropis device is effective against COVID19, well tolerated, and licensed. Here we show that split-dose, multi-site administration and intradermal delivery via the Tropis biojector increase the delivery of pBI-11 DNA vaccine, enhance HPV antigen-specific CD8+ T-cell responses, and improve anti-tumor therapeutic effects, suggesting its translational potential to treat HPV16/18 infection and disease.

HPV16 infection promotes the malignant transformation of the esophagus and progression of esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) may be correlated with HPV infection, and the mechanism underlying the ESCC formation induced by HPV16 infection remains elusive. Here, we overexpressed HPV16 E6 and E7 and coordinated the overexpression of these two genes in EPC2 and ESCC cells. We found that E7 and coordinated expression of E6 and E7 promoted the proliferation of EPC2 cells, and upregulation of shh was responsible for cell proliferation since the use of vismodegib led to the failure of organoid formation. Meanwhile, overexpression of E6 and E7 in ESCC cells promoted cell proliferation, migration, and invasion in vitro. Importantly, E6 and E7 coordinately increased the capability of tumor growth in nude mice, while vismodegib slowed the growth of tumors in NCG mice. Moreover, a series of genes and proteins changed in cell lines after overexpression of the E6 and E7 genes, the potential biological processes and pathways were systematically analyzed using a bioinformatics assay. Together, these findings suggest that the activation of the hedgehog pathway induced by HPV16 infection may initially transform basal cells in the esophagus and promote following malignant processes in ESCC cells. The application of hedgehog inhibitors may represent a therapeutic avenue for ESCC treatment.

Investigating the Potential Role of IKZF3 in HPV-Associated Carcinogenesis

HPVs cause approximately 5% of all human cancers. They encode two viral transforming proteins, E6 and E7, that are consistently expressed in these cancers. The HPV E6 and E7 proteins contribute to carcinogenesis by binding and functionally compromising multiple cellular regulatory proteins, most prominently the p53 and retinoblastoma (pRB) tumor suppressors, respectively. To discover additional cellular regulatory circuits that are dysregulated by E6 and E7 expression, we performed RNA sequencing analyses of HPV16 E6 and E7 expressing primary human genital epithelial cells. These experiments revealed that the Ikaros Zinc Finger 3 (IKZF3) transcription factor is highly upregulated in HPV16 E6/E7 expressing keratinocytes as compared to control keratinocytes. IKZF3 plays a key role in lymphocyte development, and when over-expressed or mutated, contributes to hematopoietic malignancies. IKZF3 is expressed at a very low level in normal epithelial cells, but the expression is upregulated in solid tumors, including invasive breast, cervical, and lung cancers. IKZF3 expression in these tumors causes upregulation of lymphocyte-specific genes, conferring lymphocyte-like behavior referred to as "lymphocyte mimicry," which presumably enables cancer cell survival in the bloodstream, thus potentially contributing to cancer metastasis. There is an FDA-approved drug, lenalidomide, that targets IKZF3 for degradation. Hence, we set out to determine whether IKZF3 might contribute to cervical carcinogenesis. We treated HPV16-positive SiHa and CaSki cervical cancer cells with 10 uM of lenalidomide for 12 hours. Cells were treated with equal amounts of DMSO as a negative control. Then, IKZF3 and E7 mRNA expression were determined using qRT-PCR after 12 hours of treatment. Gene expression was analyzed relative to GAPDH, and the results were analyzed using 2-way ANOVAs with Dunnett's correction for multiple comparisons. Western Blot experiments were performed to examine IKZF3, pRB, E7, and p53 (to indirectly assess E6) protein expression levels after 12 hours of lenalidomide treatment. Actin protein was used as a loading control. Each of these experiments were performed 3 times, qRT-PCR experiments were each performed in triplicate, and the results were graphed using a scientific 2-D graphing and statistics software. Although Western Blot showed that IKZF3 protein levels were significantly decreased by lenalidomide treatment, there was no change in pRB, E7, and p53 protein expression upon IKZF3 depletion. Similarly, there was no decrease in E7 mRNA expression. We showed by western blotting that targeting IKZF3 for proteasome-mediated degradation with lenalidomide effectively decreased the steady-state levels of IKZF3. However, we did not consistently observe an associated decrease in HPV gene expression. We are currently analyzing the transcriptome changes that IKZF3 depletion causes in cervical carcinoma cells to determine whether this may affect anoikis resistance.

HPV Infection Causes Dependence on Alternative DNA Damage Response Pathways Providing Cancer Specific Targets for Radiosensitization

Cancer-specific radiosensitization is an attractive approach to improving the efficacy of radiotherapy. However, drugs targeting ubiquitous DNA damage response pathways are not cancer specific and can increase radiation related side effects. Thus, there is an unmet need for tumor specific molecular targets. This approach requires an identification of DNA damage signaling pathways that are unique to cancer cells. We hypothesized that by expressing its genome in the host cells HPV infection can rewire DNA damage signaling making HPV-positive tumor cells dependent on alternative pathways to survive radiation, which can be exploited for radiosensitization of HPV-induced cancers. We have performed a CRISPR/Cas9 screen in HPV-positive SiHa cells that either express HPV16 proteins E6 and E7 or contain a selective knock-out of E6 or E7. We used next-generation sequencing to determine the abundance of gRNA in cells that were mock-treated or irradiated. We identified genes that were required for survival of radiation specifically in the context of E6 or E7 expression. Results of the screen were validated by generating knock-outs of the discovered genes using CRISPR/Cas9. By applying an array of molecular tools to analyze cell survival, cell cycle progression and mitotic progression we assessed the role of these genes in radiation response in HPV-positive cancer cells. We have identified genes that are required for survival of radiation-induced DNA damage in the context of either E6 or E7 expression. We demonstrate that targeting these genes results in hypersensitization of cervical cancer cells to radiation specifically in the presence of E6 or E7. We show that the gene product required for survival in E6-expressing cells is critical for mitotic progression after radiation exposure serving as a member of a protein complex stabilizing the attachment of mitotic spindle to centromeres. We have uncovered specific genes that are critical for DNA damage response and cell survival after radiation exposure in HPV-positive cells. Our findings suggest that expression of the HPV proteins E6 and E7 rewires DNA damage signaling causing dependence on alternative response pathways. We propose that these pathways can be targeted for a tumor-specific radiosensitization of HPV-induced cancers.