HPV16 E7 Oncoprotein Research Articles

Regulation of HPV E7 Stability by E6-Associated Protein (E6AP).

High-risk human papillomaviruses (HPVs) are responsible for most human cervical cancers, and uncontrolled expression of the two key viral oncoproteins, E6 and E7, stimulates the induction of carcinogenesis. Previous studies have shown that both E6 and E7 are closely associated with different components of the ubiquitin proteasome pathway, including several ubiquitin ligases. Most often these are utilized to target cellular substrates for proteasome-mediated degradation, but in the case of E6, the E6AP ubiquitin ligase plays a critical role in controlling E6 stability. We now show that knockdown of E6AP in HPV-positive cervical cancer-derived cells causes a marked decrease in E7 protein levels. This is due to a decrease in the E7 half-life and occurs in a proteasome-dependent manner. In an attempt to define the underlying mechanism, we show that E7 can also associate with E6AP, albeit in a manner different from that of E6. In addition, we show that E6AP-dependent stabilization of E7 also leads to an increase in the degradation of E7's cellular target substrates. Interestingly, ectopic overexpression of E6 oncoprotein results in lower levels of E7 protein through sequestration of E6AP. We also show that increased E7 stability in the presence of E6AP increases the proliferation of the cervical cancer-derived cell lines. These results demonstrate a surprising interplay between E6 and E7, in a manner which is mediated by the E6AP ubiquitin ligase. IMPORTANCE This is the first demonstration that E6AP can directly help stabilize the HPV E7 oncoprotein, in a manner similar to that observed with HPV E6. This redefines how E6 and E7 can cooperate and potentially modulate each other's activity and further highlights the essential role played by E6AP in the viral life cycle and malignancy.

Synthesis and immunogenicity of the linear conjugates of polyacrylic acid and antigenic peptide of human papillomavirus

Polyelectrolytes (polymers carrying positively or negatively charged groups) can be used as adjuvants in subunit vaccine formulations to increase the immunogenicity of antigenic molecules. A vaccine prototype can be obtained by covalently bonding antigenic molecules to polyelectrolytes or using their physical mixtures with polyelectrolytes. Covalent conjugates of polyelectrolytes with antigens are known to exhibit stronger immunogenicity compared to physical mixtures of antigens and polyelectrolytes. In this study, linear conjugates of polyacrylic acid (PAA) with an antigenic peptide sequence (STHVDIRTLEDLLMGW) of the HPV-16 E7 oncoprotein were produced. PAAs of different molecular weights with narrow dispersity were synthesized by RAFT polymerization. The linear conjugates of PAA and the peptide were obtained by covalent bonding via the chain-end thiol group of PAA and N-terminal maleimide group of the peptide using the maleimide-thiol reaction. For this purpose, the trithiocarbonate end group of the polymer was reduced with excess ethylenediamine to the thiol group. The produced PAA-peptide conjugates were characterized by GPC, fluorescence, and NMR spectroscopies. Conjugation efficiency was above 80% for all PAAs. Antigenic peptide conjugates of PAAs of different molecular weights were investigated in MTT and nitric oxide (NO) assays in which the linear PAA-peptide conjugates exhibit high biocompatibility and stimulated the macrophages to release high levels of NO.

Absolute Risk of Oropharyngeal Cancer After an HPV16-E6 Serology Test and Potential Implications for Screening: Results From the Human Papillomavirus Cancer Cohort Consortium.

Seropositivity for the HPV16-E6 oncoprotein is a promising marker for early detection of oropharyngeal cancer (OPC), but the absolute risk of OPC after a positive or negative test is unknown. We constructed an OPC risk prediction model that integrates (1) relative odds of OPC for HPV16-E6 serostatus and cigarette smoking from the human papillomavirus (HPV) Cancer Cohort Consortium (HPVC3), (2) US population risk factor data from the National Health Interview Survey, and (3) US sex-specific population rates of OPC and mortality. The nine HPVC3 cohorts included 365 participants with OPC with up to 10 years between blood draw and diagnosis and 5,794 controls. The estimated 10-year OPC risk for HPV16-E6 seropositive males at age 50 years was 17.4% (95% CI, 12.4 to 28.6) and at age 60 years was 27.1% (95% CI, 19.2 to 45.4). Corresponding 5-year risk estimates were 7.3% and 14.4%, respectively. For HPV16-E6 seropositive females, 10-year risk estimates were 3.6% (95% CI, 2.5 to 5.9) at age 50 years and 5.5% (95% CI, 3.8 to 9.2) at age 60 years and 5-year risk estimates were 1.5% and 2.7%, respectively. Over 30 years, after a seropositive result at age 50 years, an estimated 49.9% of males and 13.3% of females would develop OPC. By contrast, 10-year risks among HPV16-E6 seronegative people were very low, ranging from 0.01% to 0.25% depending on age, sex, and smoking status. We estimate that a substantial proportion of HPV16-E6 seropositive individuals will develop OPC, with 10-year risks of 17%-27% for males and 4%-6% for females age 50-60 years in the United States. This high level of risk may warrant periodic, minimally invasive surveillance after a positive HPV16-E6 serology test, particularly for males in high-incidence regions. However, an appropriate clinical protocol for surveillance remains to be established.

Deregulation of PiwiL1 and associated RNAs in cervical cancer: is HPV oncogene responsible?

Although HPV infection is the major cause of tumorigenesis in cervical cancer; interestingly it has been noted that HPV infection does not always lead to cervical cancer. This suggests that there could be some unknown factor that directly or indirectly interacts with these HPV oncoproteins leading to tumorigenesis. Our study aims to understand whether any correlation exists between the Piwi homologs with HPV oncoproteins in cervical cancer. To begin with, the expression pattern of Piwi proteins were evaluated in cultured cervical cancer (C33A, SiHa, and CaSki) cell lines. We observed that all the Piwi variants were differentially expressed in all the selected cervical cancer cell lines with PiwiL1 showing the highest expression in CaSki cells, suggesting a positive correlation with HPV oncoproteins. On investigating this correlation further, we found that PiwiL1 was co‐expressed and physically interacted with HPV oncoproteins E6 and E7. Not only E6 and E7 physically interact with PiwiL1, but also accentuated its expression when over‐expressed in HaCaT cells. Since PiwiL1 protein is known for its overexpression in many cancers, we wanted to know how this molecule is regulated in cancer. For this, we have carried out an in silico analysis of the PiwiL1 promoter to find the possible binding TFs using multiple online tools such as Alibhabha, AllegenPromo, and TFsitescan. We further shortlisted the TFs based on their function in cancer, interestingly we found both p53 and E2F in the list. Further analysis of these selected factors suggested that PiwiL1 promoter activity was significantly upregulated in the presence of E2F, whereas it was downregulated with p53. The binding of these transcription factors and their differential regulation of PiwiL1 promoter could be one of the reasons for its over‐expressed status in cancer. In addition to this, it is also known that the Piwi‐piRNA complex act as guiding signals for factors that play a significant role in tumorigenesis. Therefore, we have constructed a pipeline to predict the piRNAs from a small RNA Sequencing Data (SRP119662) obtained from the NCBI database, we identified 2274 piRNAs from both control and tumor samples, out of this, only 9 piRNAs were found to be significantly differentially expressed compared to control. Even though in silico analysis predicted 6 piRNAs to be significantly upregulated and 3 piRNAs to be significantly downregulated, the qPCR analysis was not entirely in accordance to the prediction. Out of the 3 down‐regulated piRNAs, hsa_piR_007863 showed elevated levels in CaSki in comparison to HaCaT while hsa_piR_002320 which was predicted to be upregulated in tumor showed lower expression. Our preliminary data suggest that PiwiL1 protein and associated piRNAs may have an important role in HPV‐associated tumorigenesis, whose exact molecular mechanism needs to be further evaluated.

Molecular Detection Methods in HPV-Related Cancers.

Human papillomavirus (HPV) is responsible for most cervical cancers and some head and neck cancers, including oropharyngeal squamous cell carcinoma and sinonasal carcinoma. Cervical cancer is commonly diagnosed by liquid-based cytology, followed by HPV testing using commercially available DNA polymerase chain reaction (PCR), p16 immunohistochemistry (IHC), or DNA/RNA in situ hybridization. HPV in head and neck cancers is commonly diagnosed by p16 IHC or by RT-qPCR of HPV-16 E6 and E7 oncoproteins. Droplet digital PCR has been reported as an ultrasensitive and highly precise method of nucleic acid quantification for biomarker analysis and has been used to detect oncogenic HPV in oropharyngeal and cervical cancers.

In silico Study of Natural inhibitors for Human papillomavirus-18 E6 protein

Globally, the leading cause of death from cancer in women is infection with the human papillomavirus (HPV). This calls for imperative actions to explore anticancer drugs against this threatening viral infection, in which case, natural ingredients are presumed to be a promising source. Several studies show that plant-origin compounds such as allicin, apigenin, capsaicin, cyanidin, fisetin, genistein, laricitrin, naringenin, piperine, and syringetin have demonstrated therapeutic effects against several cancer types. In this study, the interaction mechanism of these compounds with HPV-18 E6 oncoprotein, that is known to downregulate tumor suppressor p53, was predicted using an in silico approach. Molecular docking simulations of natural ligands and E6 protein were performe, followed by chemical interaction analysis and 3D molecular visualization. Results indicated that fisetin is the best natural inhibitor as it has the lowest binding energy. It is highly recommended that the results of this study be used as a reference in designing anticancer drugs in vitro and in vivo.

HnRNP D activates production of HPV16 E1 and E6 mRNAs by promoting intron retention.

Human papillomavirus type 16 (HPV16) E1 and E6 proteins are produced from mRNAs with retained introns, but it has been unclear how these mRNAs are generated. Here, we report that hnRNP D act as a splicing inhibitor of HPV16 E1/E2- and E6/E7-mRNAs thereby generating intron-containing E1- and E6-mRNAs, respectively. N- and C-termini of hnRNP D contributed to HPV16 mRNA splicing control differently. HnRNP D interacted with the components of splicing machinery and with HPV16 RNA to exert its inhibitory function. As a result, the cytoplasmic levels of intron-retained HPV16 mRNAs were increased in the presence of hnRNP D. Association of hnRNP D with HPV16 mRNAs in the cytoplasm was observed, and this may correlate with unexpected inhibition of HPV16 E1- and E6-mRNA translation. Notably, hnRNP D40 interacted with HPV16 mRNAs in an HPV16-driven tonsillar cancer cell line and in HPV16-immortalized human keratinocytes. Furthermore, knockdown of hnRNP D in HPV16-driven cervical cancer cells enhanced production of the HPV16 E7 oncoprotein. Our results suggest that hnRNP D plays significant roles in the regulation of HPV gene expression and HPV-associated cancer development.

Sustained expression of HPV16 E7 oncoprotein promotes p-AKT(Ser473)/p-Src(Tyr527) signaling to drive precancerous lesions to invasive cervical cancer.

Human papillomavirus (HPV) E7 oncogene plays the most important role in cervical cancer. However, whether E7 oncoprotein is continuously expressed, associated with AKT(Ser473)/p-Src(Tyr527) signaling to trigger cervical carcinogenesis remains unclear. Here, we explored first if HPV16 E7 oncoprotein could be detected in clinical biopsies and is sustainedly expressed, and then investigated how this oncoprotein interacted with AKT(Ser473)/p-Src(Tyr527) signaling in cancer progression. We used ZHPV16E7384 affibody to detect E7 expression in HPV16-positive cervical cancer biopsies and animal tumors by immunohistochemistry (IHC). Results showed that ZHPV16E7384 affibody had intense and specific staining for E7 oncoprotein in the detected specimen. The E7 oncoprotein was continuously expressed to correspond with the development of precancerous lesions to invasive cervical cancer. IHC staining also revealed that AKT, p-AKT(Ser473), Src and p-Src(Tyr527) proteins were expressed in both patient biopsies and animal tumors, with the highest levels of p-AKT(Ser473)/p-Src(Tyr527) present in invasive cancer. Furthermore, siRNA experiments revealed that HPV16 E7 knockdown significantly impaired expression of p-AKT(Ser473)/p-Src(Tyr527) in both HPV16 E7-positive cancer cells and transformed cells. In addition, transient expression of HPV16 E7 protein promoted significantly expression of p-AKT(Ser473)/p-Src(Tyr527) in primary human keratinocytes. Finally, co-immunoprecipitation analysis proved that HPV 16 E7 protein interacted reciprocally with p-AKT(Ser473)/p-Src(Tyr527). In conclusion, we demonstrate that HPV16 E7 oncoprotein is continuously expressed to promote expression of p-AKT(Ser473)/p-Src(Tyr527) leading to drive the initiation and progression of cervical cancer. Our data provide a novel insight that HPV16 E7 activates p-AKT(Ser473)/p-Src(Tyr527) to establish a mechanistic link between the oncogene and the AKT/Src signaling to trigger cervical carcinogenesis.

Co-Delivery of p53 Restored and E7 Targeted Nucleic Acids by Poly (Beta-Amino Ester) Complex Nanoparticles for the Treatment of HPV Related Cervical Lesions.

The p53 gene has the highest mutation frequency in tumors, and its inactivation can lead to malignant transformation, such as cell cycle arrest and apoptotic inhibition. Persistent high-risk human papillomavirus (HR-HPV) infection is the leading cause of cervical cancer. P53 was inactivated by HPV oncoprotein E6, promoting abnormal cell proliferation and carcinogenesis. To study the treatment of cervical intraepithelial neoplasia (CIN) and cervical cancer by restoring p53 expression and inactivating HPV oncoprotein, and to verify the effectiveness of nano drugs based on nucleic acid delivery in cancer treatment, we developed poly (beta-amino ester)537, to form biocompatible and degradable nanoparticles with plasmids (expressing p53 and targeting E7). In vitro and in vivo experiments show that nanoparticles have low toxicity and high transfection efficiency. Nanoparticles inhibited the growth of xenograft tumors and successfully reversed HPV transgenic mice’s cervical intraepithelial neoplasia. Our work suggests that the restoration of p53 expression and the inactivation of HPV16 E7 are essential for blocking the development of cervical cancer. This study provides new insights into the precise treatment of HPV-related cervical lesions.

A dual-signal electrochemical immunosensor for the detection of HPV16 E6 oncoprotein based on PdBP dendritic ternary nanospheres and MBSi-Chi nanocomposites.

Cervical cancer is a common cancer in women. HPV16 E6 oncoprotein is a reliable biomarker for cervical cancer. Although there are other methods for detecting E6 oncoprotein, the electrochemical method has more advantages, such as low cost, convenience and speed. In this study, a novel dual-signal electrochemical immunosensor for quick and sensitive detection of E6 oncoprotein based on a high efficiency catalyst and signal label was developed. Herein, to achieve quick detection, palladium-boron-phosphorus dendritic ternary nanospheres (PdBP NSs) not only acted as a catalyst to catalyze H2O2, but also as a support material to capture antibodies. Moreover, to realize sensitive detection, nanocomposites of mesoporous silica nanoparticles loaded with methylene blue and coated with chitosan (MBSi-Chi) were synthesized as a signal label, which can produce electrochemical signal. Under optimal conditions, the label-free immunosensor exhibited a linear range of 100 fg mL-1 to 4 ng mL-1 with a detection limit of 72.8 fg mL-1 (S/N = 3), and the sandwich-type immunosensor presented a linear range of 50 fg mL-1 to 4 ng mL-1 with a detection limit of 34.1 fg mL-1 (S/N = 3). The as-prepared dual-signal immunosensor had desirable specificity, stability and repeatability, implying its potential applications in clinical laboratory.

Inhibition of Autophagy by 3-MA Increases Oncolysis Effect of VSV in a Murine Model of Cancer

Vesicular stomatitis virus has been known as a potent antitumor agent because of its selective replication and lysis of tumor cells and immune-stimulating properties. In response to cellular stress and enhanced metabolism, tumor cells activate autophagy, to provide energy for the cells and preventing tumor destruction. Inhibition of autophagy can increase the therapeutic potential of many antitumor methods. This study aimed to check the efficacy of combined VSV and three-methyl adenine (3-MA) in treating a tumor model in mice. TC-1, a line of C57BL/6 mouse lung cells transformed by HPV-16 E7 and E6 oncoproteins, as well as human Ras, were used for experiments. The viability after treatment with the optimized concentration of 3-MA with or without combination with VSV was assessed by MTT. C57BL/6 male mice were injected with TC-1, and after tumor formation, 3-MA and VSV alone or in combination in two different protocols were injected into tumor mice. Tumor size, tumor-specific CTL response, and apoptosis rate were evaluated. The results showed that 3-MA combined with VSV causes more lethality in tumor cells in vitro. In vivo studies also showed that combined VSV and 3-MA treatment inhibits the progression of TC-1 cancer cells with higher efficiency, especially in daily 3-MA treatment along with four doses of VSV injection with four days' intervals. In addition, the rate of apoptosis and cytotoxic T cells activity in the groups injected with 3-MA and the virus were higher than groups receiving each agent alone. In conclusion, the association of VSV with 3-MA increases its oncolysis activity and subsequently more stimulates the immune system against the tumor. This finding suggests a combinational approach for tumor therapy with therapy. Combining oncolytic VSV with 3-MA as an autophagy inhibitor agent can improve the efficacy of tumor treatment. This combination therapy approach enhances apoptosis in tumors as well as T cell cytotoxicity against tumor cells.

Targeted Disruption of E6/p53 Binding Exerts Broad Activity and Synergism with Paclitaxel and Topotecan against HPV-Transformed Cancer Cells.

Simple SummaryThe identification of new specific anti-human papillomavirus (HPV) drugs is highly needed, as HPV-induced cancers still represent a significant medical issue. The aim of this study was to analyze in more detail the therapeutic potential of a compound, Cpd12, that acts by blocking the binding between HPV E6 oncoprotein and cellular tumor suppressor p53. We demonstrated that by blocking such an interaction, driven by highly conserved residues among oncogenic HPVs, Cpd12 exhibits broad activity against cervical cancer cell lines infected by different HPV genotypes and HPV-positive head-and-neck cancer cells. Interestingly, Cpd12 also showed the ability to inhibit cancer cell migration and to increase the activity of chemotherapeutic drugs such as taxanes and topoisomerase inhibitors. These findings improve the knowledge about the in vitro efficacy of Cpd12, paving the way to preclinical studies to develop new therapeutic strategies against HPV-induced tumors.High-risk human papillomaviruses (HR-HPV) are the etiological agents of almost all cervical cancer cases and a high percentage of head-and-neck malignancies. Although HPV vaccination can reduce cancer incidence, its coverage significantly differs among countries, and, therefore, in the next decades HPV-related tumors will not likely be eradicated worldwide. Thus, the need of specific treatments persists, since no anti-HPV drug is yet available. We recently discovered a small molecule (Cpd12) able to inhibit the E6-mediated degradation of p53 through the disruption of E6/p53 binding in HPV16- and HPV18-positive cervical cancer cells. By employing several biochemical and cellular assays, here we show that Cpd12 is also active against cervical cancer cells transformed by other HR-HPV strains, such as HPV68 and HPV45, and against a HPV16-transformed head-and-neck cancer cell line, suggesting the possibility to employ Cpd12 as a targeted drug against a broad range of HPV-induced cancers. In these cancer cell lines, the antitumoral mechanism of action of Cpd12 involves p53-dependent cell cycle arrest, a senescent response, and inhibition of cancer cell migration. Finally, we show that Cpd12 can strongly synergize with taxanes and topoisomerase inhibitors, encouraging the evaluation of Cpd12 in preclinical studies for the targeted treatment of HPV-related carcinomas.

HPV16 E1 dysregulated cellular genes involved in cell proliferation and host DNA damage: A possible role in cervical carcinogenesis.

HPV16 is the most prominent cause of cervical cancer. HPV16 E1, a helicase required for HPV replication exhibits increased expression in association with cervical cancer progression, suggesting that E1 has a similar effect on the host as the HPV16 E6 and E7 oncoproteins. This study aimed to determine whether expression of HPV16 E1 correlated with carcinogenesis by modulating cellular pathways involved in cervical cancer. HEK293T cells were transfected with pEGFP, pEGFPE1 or truncated forms of HPV16 E1. Cell proliferation, cell death, and the impact of HPV16 E1 on host gene expression was then evaluated. HPV16 E1 overexpression resulted in a significant reduction of cell viability and cellular proliferation (p-value<0.0001). Moreover, prolonged expression of HPV16 E1 significantly induced both apoptotic and necrotic cell death, which was partially inhibited by QVD-OPH, a broad-spectrum caspase inhibitor. Microarray, real time RT-PCR and kinetic host gene expression analyses revealed that HPV16 E1 overexpression resulted in the downregulation of genes involved in protein synthesis (RPL36A), metabolism (ALDOC), cellular proliferation (CREB5, HIF1A, JMJDIC, FOXO3, NFKB1, PIK3CA, TSC22D3), DNA damage (ATR, BRCA1 and CHEK1) and immune response (ISG20) pathways. How these genetic changes contribute to HPV16 E1-mediated cervical carcinogenesis warrants further studies.

Comprehensive Analysis of VEGFR2 Expression in HPV-Positive and -Negative OPSCC Reveals Differing VEGFR2 Expression Patterns.

Simple SummaryUp to 50% of oropharyngeal squamous cell carcinomas (OPSCC) are associated with human papillomavirus type 16 (HPV16), the annual incidence of which is steadily increasing. HPV-positive and -negative OPSCC exhibit a different biology, which is characterized by distinct mutation signatures and expression patterns. It is known that VEGFR2 is commonly overexpressed in HNSCC, but the influence of HPV on VEGFR2 in OPSCC is still unknown, although VEGFR2 has emerged as a promising target in tumor therapy. The aim of our study was to evaluate whether HPV exerts specific effects on VEGFR2 expression in OPSCC and thus possibly on the regulation of vascularization. Interestingly, while HPV-negative carcinoma upregulates VEGFR2 in tumor cells, in HPV-positive carcinoma VEGFR2 is upregulated in tumor-supporting blood vessels. HPV-positive OPSCC with high VEGFR2 expression is associated with poor prognosis, supporting the prognostic significance of deregulated VEGF signaling for OPSCC patients.VEGF signaling regulated by the vascular endothelial growth factor receptor 2 (VEGFR2) plays a decisive role in tumor angiogenesis, initiation and progression in several tumors including HNSCC. However, the impact of HPV-status on the expression of VEGFR2 in OPSCC has not yet been investigated, although HPV oncoproteins E6 and E7 induce VEGF-expression. In a series of 56 OPSCC with known HPV-status, VEGFR2 expression patterns were analyzed both in blood vessels from tumor-free and tumor-containing regions and within tumor cells by immunohistochemistry using densitometry. Differences in subcellular colocalization of VEGFR2 with endothelial, tumor and stem cell markers were determined by double-immunofluorescence imaging. Immunohistochemical results were correlated with clinicopathological data. HPV-infection induces significant downregulation of VEGFR2 in cancer cells compared to HPV-negative tumor cells (p = 0.012). However, with respect to blood vessel supply, the intensity of VEGFR2 staining differed only in HPV-positive OPSCC and was upregulated in the blood vessels of tumor-containing regions (p < 0.0001). These results may suggest different routes of VEGFR2 signaling depending on the HPV-status of the OPSCC. While in HPV-positive OPSCC, VEGFR2 might be associated with increased angiogenesis, in HPV-negative tumors, an autocrine loop might regulate tumor cell survival and invasion.

The Not-So-Good, the Bad and the Ugly: HPV E5, E6 and E7 Oncoproteins in the Orchestration of Carcinogenesis.

Infection with HPV starts with the access of the viral particles to basal cells in the epidermis, potentially via microtraumas to the skin. The basal cells are able to keep away these pathogens in normal circumstances through a robust immune response from the host, as HPV infections are, in general, cleared within 2 to 3 weeks. However, the rare instances of persistent infection and/or in cases where the host immune system is compromised are major risk factors for the development of lesions potentially leading to malignancy. Evolutionarily, obligatory pathogens such as HPVs would not be expected to risk exposing the host to lethal cancer, as this would entail challenging their own life cycle, but infection with these viruses is highly correlated with cancer and malignancy—as in cancer of the cervix, which is almost always associated with these viruses. Despite this key associative cause and the availability of very effective vaccines against these viruses, therapeutic interventions against HPV-induced cancers are still a challenge, indicating the need for focused translational research. In this review, we will consider the key roles that the viral proteins play in driving the host cells to carcinogenesis, mainly focusing on events orchestrated by early proteins E5, E6 and E7—the not-so-good, the bad and the ugly—and discuss and summarize the major events that lead to these viruses mechanistically corrupting cellular homeostasis, giving rise to cancer and malignancy.

Development of models for cervical cancer screening: construction in a cross-sectional population and validation in two screening cohorts in China

BackgroundCurrent methods for cervical cancer screening result in an increased number of referrals and unnecessary diagnostic procedures. This study aimed to develop and evaluate a more accurate model for cervical cancer screening.MethodsMultiple predictors including age, cytology, high-risk human papillomavirus (hrHPV) DNA/mRNA, E6 oncoprotein, HPV genotyping, and p16/Ki-67 were used for model construction in a cross-sectional population including women with normal cervix (N = 1085), cervical intraepithelial neoplasia (CIN, N = 279), and cervical cancer (N = 551) to predict CIN2+ or CIN3+. A base model using age, cytology, and hrHPV was calculated, and extended versions with additional biomarkers were considered. External validations in two screening cohorts with 3-year follow-up were further conducted (NCohort-I = 3179, NCohort-II = 3082).ResultsThe base model increased the area under the curve (AUC, 0.91, 95% confidence interval [CI] = 0.88–0.93) and reduced colposcopy referral rates (42.76%, 95% CI = 38.67–46.92) compared to hrHPV and cytology co-testing in the cross-sectional population (AUC 0.80, 95% CI = 0.79–0.82, referrals rates 61.62, 95% CI = 59.4–63.8) to predict CIN2+. The AUC further improved when HPV genotyping and/or E6 oncoprotein were included in the base model. External validation in two screening cohorts further demonstrated that our models had better clinical performances than routine screening methods, yielded AUCs of 0.92 (95% CI = 0.91–0.93) and 0.94 (95% CI = 0.91–0.97) to predict CIN2+ and referrals rates of 17.55% (95% CI = 16.24–18.92) and 7.40% (95% CI = 6.50–8.38) in screening cohort I and II, respectively. Similar results were observed for CIN3+ prediction.ConclusionsCompared to routine screening methods, our model using current cervical screening indicators can improve the clinical performance and reduce referral rates.

Targeting Human Papillomavirus-Associated Cancer by Oncoprotein-Specific Recombinant Antibodies.

In recent decades, recombinant antibodies against specific antigens have shown great promise for the therapy of infectious diseases and cancer. Human papillomaviruses (HPVs) are involved in the development of around 5% of all human cancers and HPV16 is the high-risk genotype with the highest prevalence worldwide, playing a dominant role in all HPV-associated cancers. Here, we describe the main biological activities of the HPV16 E6, E7, and E5 oncoproteins, which are involved in the subversion of important regulatory pathways directly associated with all known hallmarks of cancer. We then review the state of art of the recombinant antibodies targeted to HPV oncoproteins developed so far in different formats, and outline their mechanisms of action. We describe the advantages of a possible antibody-based therapy against the HPV-associated lesions and discuss the critical issue of delivery to tumour cells, which must be addressed in order to achieve the desired translation of the antibodies from the laboratory to the clinic.

Molecular Landscape and Computational Screening of the Natural inhibitors against HPV16 E6 Oncoprotein.

Background:Human Papillomavirus (HPV) is a small, non-enveloped, icosahedral and double-stranded DNA virus with a genome of 8 kb, belonging to the papillomaviridae family. HPV has been associated with 99.7% cases of cervical squamous cell carcinoma worldwide. The HPV E6 protein is known as a potent oncogene and is closely allied with the events that result in the malignant transformation of virally infected cells. Objective:The present study aims to target plant derived anticancer molecules for HPV driven cancer using a computational approach. Methods: In this study, E6 oncoprotein was targeted by 101 plant-derived nutraceuticals using the molecular docking method. The multiple sequence analysis and phylogenetic analysis of low risk and high risk 28 HPV E6 proteins were performed. Results:Withanolide D, Ginkgetin, Theaflavin, Hesperidin, and Quercetin-3-gluconide were identified as the potential inhibitors of HPV 16 E6 protein. The zinc finger domain was identified on all variants of HPV E6 oncoprotein while high-risk HPV18, HPV31, HPV33, HPV35, HPV39, HPV45, HPV58, HPV68 and HPV73: probable risk HPV53 and low-risk HPV43 and HPV70 contain PDZ domain. Conclusion:The current study using bioinformatics analysis approaches reveals a promising platform for developing anti-cancerous competitive inhibitors targeting HPV.

Serum HPV16 E7 Oncoprotein Is a Recurrence Marker of Oropharyngeal Squamous Cell Carcinomas

Simple SummaryClassical markers alone, such as HPV DNA, p16 and HPV mRNA expression, are not enough to stratify HPV-positive head and neck squamous cell carcinoma (HNSCC) patients, but when combined with serological markers, the latter are strong indicators of prognosis in oropharyngeal squamous cell carcinoma (OPSCC) patients. Specifically, HPV16 E7 oncoprotein in serum at the time of diagnosis, correlates with disease recurrence and patient overall survival. To our knowledge, this is the first study to investigate HPV E7 oncoprotein in patient serum. The E7 oncoprotein detection in serum at the time of diagnosis may be useful as a non-invasive procedure for HPV-positive OPSCC patient stratification and follow-up, helping to identify patients at risk for tumor recurrence and metastasis during follow-up, and ultimately, providing a tool for clinicians to identify patients for de-escalation treatment or those to be kept under close surveillance.Despite improved prognosis for many HPV-positive head and neck squamous cell carcinomas (HNSCCs), some cases are still marked by recurrence and metastasis. Our study aimed to identify novel biomarkers for patient stratification. Classical HPV markers: HPV-DNA, p16 and HPV mRNA expression were studied in HNSCC (n = 67) and controls (n = 58) by qPCR. Subsequently, ELISA tests were used for HPV16 L1 antibody and HPV16 E7 oncoprotein detection in serum at diagnosis and follow-up. All markers were correlated to relapse-free survival (RFS) and overall survival (OS). HPV-DNA was found in HNSCCs (29.85%), HPV16-DNA in 95% of cases, HPV16 E7 mRNA was revealed in 93.75%. p16 was overexpressed in 75% of HPV-positive HNSCC compared to negative samples and controls (p < 0.001). Classical markers correlated with improved OS (p < 0.05). Serological studies showed similar proportions of HPV16 L1 antibodies in all HNSCCs (p > 0.05). Serum E7 oncoprotein was present in 30% HPV-positive patients at diagnosis (p > 0.05) and correlated to HNSCC HPV16 E7 mRNA (p < 0.01), whereas it was associated to worse RFS and OS, especially for oropharyngeal squamous cell carcinoma (OPSCC) (p < 0.01). Detection of circulating HPV16 E7 oncoprotein at diagnosis may be useful for stratifying and monitoring HPV-positive HNSCC patients for worse prognosis, providing clinicians a tool for selecting patients for treatment de-escalation.

Abstract 1210: NFX1-123: A potential therapeutic target in cancer

Abstract Background: NFX1-123 is the longer splice variant isoform of the NFX1 gene and is highly expressed in cervical cancer. Cervical cancer is caused by high-risk HPV infections, and NFX1-123 is a protein partner with the HPV oncoprotein E6. Together, NFX1-123 and E6 affect cellular growth, longevity, differentiation, and the immune response. The expression status of NFX1-123 in cancers beyond cervical cancer, and its potential as therapeutic target, has not been investigated. Methods: TSVdb of TCGA was used to quantify NFX1-123 expression in 25 primary cancers tissues compared to adjacent normal tissues. The NFX1-123 protein structure was predicted using I-TASSER: Interactive Threading ASSEmbly Refinement tool. The modeled structure was submitted to the MTi-Openscreen Virtual screening web-server using ZINC-Database to retrieve suitable drug molecules, and further screening was evaluated by PyRx interphase and AutoDock Vina. The top four compounds, found to bind in silico to NFX1-123, were tested experimentally to determine their inhibitory effects on NFX1-123-related cellular growth and survival by MTT assay. Results: 44% of cancers (11 of 25) had significant differences in NFX1-123 expression when compared to adjacent normal solid tissues. Nine of 11 cancers (88%) had greater NFX1-123 expression: breast invasive carcinoma, cholangiocarcinoma, colon adenocarcinoma, renal cell carcinoma, renal papillary cell carcinoma, hepatocellular carcinoma, lung adenocarcinoma, sarcoma, and stomach adenocarcinoma. Two of 11 cancers (18%) had reduced NFX1-123 expression: lung squamous cell carcinoma, and pheochromocytoma and paraganglioma. Additionally, HPV+ head and neck cancers had greater expression of NFX1-123 compared to HPV- head and neck cancers. Bioinformatics and proteomic predictive analysis revealed the 3-D structure of the NFX1-123; with this structure, drug libraries were screened for high binding affinity compounds. 17 drugs with binding energies range from -11.3 to -10 Kcal/mol. were found. The top four compounds were used to treat HPV- and HPV+ cervical and head and neck cancer cell lines in culture, and two (R428 and Ketoconazole) were found to reduce NFX1-123 protein levels and inhibit cell growth and survival. R428 was also found to inhibit NFX1-123 and regulate autophagy and autophagy-mediated cell death. Conclusion: Nine out of 25 (36%) cancers expressed high levels of NFX1-123, and drug targeting of NFX1-123 can lead to cell growth inhibition. NFX1-123 may be a potential novel therapeutic target in cancers that highly express NFX1-123. Citation Format: Sreenivasulu Chintala, Anand Anbarasu, Rachel A. Katzenellenbogen. NFX1-123: A potential therapeutic target in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1210.