Molecular mechanisms underlying human papillomavirus E6 and E7 oncoprotein-induced cell transformation

High-risk HPV oncoproteins E6 and E7 and their interplay with the innate immune response: Uncovering mechanisms of immune evasion and therapeutic prospects

Human papillomaviruses (HPVs) are double-stranded DNA (dsDNA) tumor viruses causally associated with 5% of human cancers, comprising both anogenital and upper aerodigestive tract carcinomas. Despite the availability of prophylactic vaccines, HPVs continue to pose a significant global health challenge, primarily due to inadequate vaccine access and coverage. These viruses can establish persistent infections by evading both the intrinsic defenses of infected tissues and the extrinsic defenses provided by professional innate immune cells. Crucial for their evasion strategies is their unique intraepithelial life cycle, which effectively shields them from host detection. Thus, strategies aimed at reactivating the innate immune response within infected or transformed epithelial cells, particularly through the production of type I interferons (IFNs) and lymphocyte-recruiting chemokines, are considered viable solutions to counteract the adverse effects of persistent infections by these oncogenic viruses. This review focuses on the complex interplay between the high-risk HPV oncoproteins E6 and E7 and the innate immune response in epithelial cells and HPV-associated cancers. In particular, it details the molecular mechanisms by which E6 and E7 modulate the innate immune response, highlighting significant progress in our comprehension of these processes. It also examines forward-looking strategies that exploit the innate immune system to ameliorate existing anticancer therapies, thereby providing crucial insights into future therapeutic developments.

Microbiome reveals inflammatory-related bacteria and putative functional pathways involved in human papillomavirus-associated penile squamous cell carcinoma

BACKGROUND

Penile squamous cell carcinoma (PSCC) is a rare disease that is more prevalent in developing countries, such as Brazil, and is linked to poor genital hygiene, which promotes the proliferation of microorganisms. Dysbiosis has an effect on the local immune response, increases the risk of viral infection, and can generate inflammatory processes. Current knowledge of the microbiota found in penile tissues is limited, and the bacterial diversity of the PSCC remains unknown. In this investigation, the microbiota associated with penile cancer and its potential role in tumor development and progression were identified.

METHODS

The 16S rRNA gene was analyzed by next-generation sequencing in 19 tumors and their respective non-tumor adjacent tissues to perform taxonomic classification, analysis of core microbiome, abundance, and diversity of amplicon sequence variants (ASVs) (QIIME2 v.2020.2), and in silico functional prediction (PICRUST2, p < 0.05).

RESULTS

In both tissues, the phyla Proteobacteria and Firmicutes, and genera Alcaligenes and Fusobaterium, were the most prevalent. Tumors presented a greater relative abundance of Fusobacteriota, Campilobacteria, and Fusobacterium (p = 0.04, p = 0.04, and p = 0.039, respectively). In addition, the beta diversity analysis revealed a tendency for the formation of two distinct groups when only advanced tumors (pT2 and pT3) were considered. Further, the functional analysis identified the top 35 pathways, and 79.5% of PSCC samples contained pro-inflammatory microorganisms.

CONCLUSION

We describe the first microbiome of penile carcinoma, which revealed an abundant and diverse microbiota as well as inflammatory-related taxa (the phyla Proteobacteria and Firmicutes, the genera Fusobacterium and Prevotella, and the species Finegoldia magma and Pseudomonas geniculata) and molecular pathways (chitin derivates degradation, the protocatechuic acid pathway, inositol metabolism, and the sucrose pathway), which have also been linked to inflammation and carcinogenesis. Moreover, we found specific and abundant ASVs in both tumor and non-tumor tissues. Our data encourage further study to better understand the role of these microorganisms in penile carcinogenesis, offering an opportunity for advances in diagnosis, prognosis, and early therapy.

Detection of α-papillomaviruses in extragenital cutaneous squamous cell carcinomas

Previous studies have demonstrated that human papillomaviruses (HPVs) of the beta genus can contribute to the onset of cutaneous carcinomas in organ transplant recipients. In contrast, there are limited data related to the oncogenicity of alpha (α)-HPVs in the skin. Herein, we explore the characteristics of three cutaneous squamous cell carcinomas presenting α-HPV infection occurring in patients with HIV, in order to determine the role of α-HPV in these skin cancers.

Laurencia johnstonii extract reverses early lesions in the K14E7HPV16 murine cervical carcinogenesis model

Persistent infection with high-risk human papillomavirus (HR-HPV) is a well-established risk factor to the development of cervical intraepithelial neoplasia (CIN), a condition that can progress to cervical cancer (CC) a major health problem worldwide. Recently, there has been growing interest in exploring alternative therapies utilizing natural products, among which is the algae species Laurencia johnstonii Setchell & Gardner, 1924 (L. johnstonii), proposed for the management of precancerous lesions. The aim of this work was to determine the effect of an organic extract from L. johnstonii (ELj) in early cervical lesions (CIN 1). These CIN 1 lesions were generated in a murine model expressing the HR-HPV16 E7 oncoprotein (K14E7HPV transgenic mice) with a single exogenous hormonal stimulus using 17β-estradiol. The histopathological studies, the determination of cell proliferation and of the apoptotic levels in cervical tissue, showed that, seven doses of ELj (30 mg/kg weight per day diluted in a DMSO-saline solution [1:7]) lead to recovery the architecture of cervical epithelium. Accordingly, in the transgenic mice it was observed a statistically significant decrease of the PCNA expression levels, a marker of cell proliferation, and a statistically significant increase in the apoptosis levels using Caspase 3 as a marker. In addition, we determined the expression levels of the tumor suppressor miR-218 and the oncomiRNA miR-21. Interestingly, our results may suggest that ELj treatment tended to restore the normal expression of both miRNAs as compared with controls being more evident in the non-transgenic induced mice. Differences of p < 0.05 were considered statistically significant through the whole study. Based on these results, we propose that the use of ELj could be an alternative for the treatment of cervical early lesions.

PAD-mediated citrullination is a novel candidate diagnostic marker and druggable target for HPV-associated cervical cancer

Citrullination is an emerging post-translational modification catalyzed by peptidyl-arginine deiminases (PADs) that convert peptidyl-arginine into peptidyl-citrulline. In humans, the PAD family consists of five isozymes (PADs 1-4, 6) involved in multiple diseases, including cancer. Given that high-risk (hr) human papillomaviruses (HPVs) are the etiological agents of cervical cancer, in this study, we sought to determine whether PAD-mediated protein citrullination would play a functional role in the HPV-driven transformation of epithelial cells. Here we show that both total protein citrullination and PAD4 expression levels are significantly associated with cervical cancer progression. Specifically, epithelial immunostaining for PAD4 revealed an increasingly higher histoscore from low-grade (CIN1) to high-grade (CIN2, CIN3) cervical intraepithelial neoplasia, and invasive squamous cell carcinoma (SCC) lesions, raising the attractive possibility that PAD4 may be used as tumor staging markers. Furthermore, taking advantage of the epidermoid cervical cancer cell line CaSki, which harbors multiple copies of the integrated HPV16 genome, we show that the expression of E6 and E7 HPV oncoproteins is impaired by treatment with the pharmacological pan-PAD inhibitor BB-Cl-amidine. Consistently, p53 and p21, two targets of HPV oncoproteins, are upregulated by the PAD inhibitor, which undergoes cell growth arrest and apoptosis. Altogether, these findings highlight a novel mechanism by which hrHPVs alter host regulatory pathways involved in cell cycle and survival to gain viral fitness, raising the possibility that PADs may represent an attractive target for developing novel host-targeting antivirals effective in preventing cervical cancer progression.

Human Oncogenic Viruses: Characteristics and Prevention Strategies-Lessons Learned from Human Papillomaviruses

Approximately 12% of human cancers worldwide are associated with infectious agents, which are classified by the International Agency for Research on Cancer (IARC) as Group 1 within the agents that are carcinogenic to humans. Most of these agents are viruses. Group 1 oncogenic viruses include hepatitis C virus, hepatitis B virus (HBV), human T-cell lymphotropic virus type 1, Epstein-Barr virus, Kaposi sarcoma-associated herpesvirus, human immunodeficiency virus-1 and high-risk human papillomaviruses (HPVs). In addition, some human polyomaviruses are suspected of inducing cancer prevalently in hosts with impaired immune responses. Merkel cell polyomavirus has been associated with Merkel cell carcinoma and included by the IARC in Group 2A (i.e., probably carcinogenic to humans). Linking viruses to human cancers has allowed for the development of diagnostic, prophylactic and therapeutic measures. Vaccination significantly reduced tumours induced by two oncogenic viruses as follows: HBV and HPV. Herein, we focus on mucosal alpha HPVs, which are responsible for the highest number of cancer cases due to tumour viruses and against which effective prevention strategies have been developed to reduce the global burden of HPV-related cancers.

Genetic and epigenetic alterations in DNA repair genes and treatment outcome of chemoradiotherapy in cervical cancer

Cervical cancer (CaCx) is the deadliest malignancy among women which is caused by human papillomavirus (HPV) and anthro-demographical/clinicopathological factors. HPV oncoproteins E6 and E7 target p53 and RB (retinoblastoma) protein degradation, Ataxia telangiectasia mutated (ATM), ATM-RAD3-related (ATR) inactivation and subsequent impairment of non-homologous end joining (NHEJ), homologous recombination, and base excision repair pathways. There is also an accumulation of genetic and epigenetic alterations in Tumor Growth Suppressors (TGS), oncogenes, and DNA repair genes leading to increased genome instability and CaCx development. These alterations might be responsible for differential clinical response to Cisplatin-based chemoradiotherapy (CRT) in patients. This review explores HPV-mediated DNA damage as a risk factor in CaCx development, the mechanistic role of genetic and epigenetic alterations in DNA repair genes and their association with CRT and outcome, It also explores new possibilities for the development of genetic and epigenetic-based biomarkers for diagnostic, prognostic, and molecular therapeutic interventions.

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.

Fragment-based design and MD simulations of human papilloma virus-16 E6 protein inhibitors

The main objective of this study is to screen potential small molecule inhibitors against HPV (Human Papilloma Virus)-16 E6 protein (HPV16 E6P) using a fragment-based approach. Twenty-six natural HPV inhibitors were selected based on the review of the literature. Among them, Luteolin was selected as the reference compound. These 26 compounds were used to generate novel inhibitors against HPV16 E6P. Fragment script and BREED of Schrodinger software were used to build novel inhibitor molecules. The result in 817 novel molecules was docked into the active binding site of HPV E6 protein and the top ten compounds were screened based on binding affinity compared to Luteolin for further study. Compounds Cpd5, Cpd7, and Cpd10 were the most potent inhibitors of HPV16 E6P and these were non-toxic and showed high Gastrointestinal (GI) absorption and positive drug-likeness score. Complexes of these compounds were stable in the 200 ns Molecular Dynamics (MD) simulation. These 3 HPV16 E6P inhibitors could be the lead molecules as new drugs for HPV-related diseases.Communicated by Ramaswamy H. Sarma.

The effects of HPV oncoproteins on host communication networks: Therapeutic connotations

Human papillomavirus (HPV) infections are a leading cause of viral-induced malignancies worldwide, with a prominent association with cervical and head and neck cancers. The pivotal role of HPV oncoproteins, E5, E6, and E7, in manipulating cellular events, which contribute to viral pathogenesis in various ways, has been extensively documented. This article reviews the influence of HPV oncoproteins on cellular signaling pathways within the host cell, shedding light on the underlying molecular mechanisms. A comprehensive understanding of these molecular alterations is essential for the development of targeted therapies and strategies to combat HPV-induced premalignancies and prevent their progress to cancer. Furthermore, this review underscores the intricate interplay between HPV oncoproteins and some of the most important cellular signaling pathways: Notch, Wnt/β-catenin, MAPK, JAK/STAT, and PI3K AKT/mTOR. The treatment efficacies of the currently available inhibitors on these pathways in an HPV-positive context are also discussed. This review also highlights the importance of continued research to advance our knowledge and enhance therapeutic interventions for HPV-associated diseases.

Anti-tumor Effects of Cisplatin Synergist in Combined Treatment with Clostridium novyi-NT Spores Against Hypoxic Microenvironments in a Mouse Model of Cervical Cancer Caused by TC-1 Cell Line

Purpose

Despite the development of anti-human papillomavirus (HPV) vaccines, cervical cancer is still a common disease in women, especially in developing countries. The presence of a hypoxic microenvironment causes traditional treatments to fail. In this study, we presented a combined treatment method based on the chemotherapeutic agent cisplatin and Clostridium novyi-NT spores to treat normoxic and hypoxic areas of the tumor.

Methods

TC-1 Cell line capable of expressing HPV-16 E6/7 oncoproteins was subcutaneously transplanted into female 6-8 week old C57/BL6 mice. The tumor-bearing mice were randomly divided into four groups and treated with different methods after selecting a control group. Group 1: Control without treatment (0.1 mL sterile PBS intratumorally), Group: C. novyi-NT (107 C. novyi-NT). Group 3: Receives cisplatin intraperitoneally (10 mg/kg). Fourth group: Intratumoral administration of C. novyi-NT spores + intraperitoneal cisplatin. Western blot analysis was used to examine the effects of anti-hypoxia treatment and expression of hypoxia-inducible factor 1 (HIF-1) and vascular endothelial growth factor (VEGF) proteins.

Results

The results clearly showed that combined treatment based on C. novyi-NT and cisplatin significantly reduced the expression of HIF-1 alpha and VEGF proteins compared to cisplatin alone. At the same time, the amount of necrosis of tumor cells in the combined treatment increased significantly compared to the single treatment and the control. At the same time, the mitotic count decreased significantly.

Conclusion

Our research showed that developing a combined treatment method based on C. novyi-NT and cisplatin against HPV-positive cervical cancer could overcome the treatment limitations caused by the existence of hypoxic areas of the tumor.

SIRT1 is an actionable target to restore p53 function in HPV-associated cancer therapy

BACKGROUND

Our aim was to evaluate the efficacy and anti-cancer action of a precision medicine approach involving a novel SIRT1-dependent pathway that, when disrupted, leads to the restoration of a functional p53 in human papillomavirus (HPV)-transformed cells.

METHODS

The anticancer potential of inhibiting SIRT1 was evaluated by examining the effects of the specific SIRT1 inhibitor EX527 (also known as Selisistat) or genetic silencing, either individually or in conjunction with standard chemotherapeutic agents, on a range of HPV+ cancer cells and a preclinical mouse model of HPV16-induced cancer.

RESULTS

We show that SIRT1 inhibition restores a transcriptionally active K382-acetylated p53 in HPV+ but not HPV- cell lines, which in turn promotes G0/G1 cell cycle arrest and inhibits clonogenicity specifically in HPV+ cells. Additionally, EX527 treatment increases the sensitivity of HPV+ cells to sublethal doses of standard genotoxic agents. The enhanced sensitivity to cisplatin as well as p53 restoration were also observed in an in vivo tumorigenicity assay using syngeneic C3.43 cells harbouring an integrated HPV16 genome, injected subcutaneously into C57BL/6J mice.

CONCLUSIONS

Our findings uncover an essential role of SIRT1 in HPV-driven oncogenesis, which may have direct translational implications for the treatment of this type of cancer.

A novel antimycin analogue antimycin A2c, derived from marine Streptomyces sp., suppresses HeLa cells via disrupting mitochondrial function and depleting HPV oncoproteins E6/E7

AIMS

Novel antimycin alkaloid antimycin A2c (AE) was isolated from the culture of a marine derived Streptomyces sp. THS-55. We elucidated its chemical structure by extensive spectra and clarified the specific mechanism in HPV infected-cervical cancer.

MATERIALS AND METHODS

Colony formation assay, cell cycle analysis, hoechst 33342 staining assay, et.al were used to detect the inhibitory effect of AE on cervical cancer cells. Meanwhile, flow cytometry, western blotting, immunoprecipitation, RNA interference and molecular docking were used to analyze the mechanism of AE.

KEY FINDINGS

AE exhibited potent cytotoxicity in vitro against HPV-transformed cervical cancer HeLa cell line. AE inhibited the proliferation, arrested cell cycle distribution, and triggered caspase dependent apoptosis in HeLa cells. Further studies revealed AE-induced apoptosis is mediated by the degradation of E6/E7 oncoproteins. Molecular mechanic investigation showed that AE degraded the levels of E6/E7 oncoproteins through reactive oxygen (ROS)-mediated ubiquitin-dependent proteasome system activation, and the increased ROS generation was due to the disruption of the mitochondrial function.

SIGNIFICANCE

This present work revealed that this novel marine derived antimycin alkaloid could target the mitochondria and subsequently degrade HPV E6/E7 oncoproteins, and have potential application in the design and development of lead compound for cervical cancer cells, as well as the development for tool compounds to dissect E6/E7 functions.

Immune microenvironment of cervical cancer and the role of IL-2 in tumor promotion

The tumor microenvironment (TME) is a heterogeneous mixture of resident and tumor cells that maintain close communication through their secretion products. The composition of the TME is dynamic and complex among the different types of cancer, where the immune cells play a relevant role in the elimination of tumor cells, however, under certain circumstances they contribute to tumor development. In cervical cancer (CC) the human papilloma virus (HPV) shapes the microenvironment in order to mediate persistent infections that favors transformation and tumor development. Interleukin-2 (IL-2) is an important TME cytokine that induces CD8+ effector T cells and NKs to eliminate tumor cells, however, IL-2 can also suppress the immune response through Treg cells. Recent studies have shown that CC cells express the IL-2 receptor (IL-2R), that are induced to proliferate at low concentrations of exogenous IL-2 through alterations in the JAK/STAT pathway. This review provides an overview of the main immune cells that make up the TME in CC, as well as the participation of IL-2 in the tumor promotion. Finally, it is proposed that the low density of IL-2 produced by immunocompetent cells is used by tumor cells through its IL-2R as a mechanism to proliferate simultaneously depleting this molecule in order to evade immune response.

Functions and mechanism of noncoding RNA in regulation and differentiation of male mammalian reproduction

Noncoding RNAs (ncRNAs) are active regulators of a wide range of biological and physiological processes, including the majority of mammalian reproductive events. Knowledge of the biological activities of ncRNAs in the context of mammalian reproduction will allow for a more comprehensive and comparative understanding of male sterility and fertility. In this review, we describe recent advances in ncRNA-mediated control of mammalian reproduction and emphasize the importance of ncRNAs in several aspects of mammalian reproduction, such as germ cell biogenesis and reproductive organ activity. Furthermore, we focus on gene expression regulatory feedback loops including hormones and ncRNA expression to better understand germ cell commitment and reproductive organ function. Finally, this study shows the role of ncRNAs in male reproductive failure and provides suggestions for further research.

The RIG-I agonist M8 triggers cell death and natural killer cell activation in human papillomavirus-associated cancer and potentiates cisplatin cytotoxicity

Although the activation of innate immunity to treat a wide variety of cancers is gaining increasing attention, it has been poorly investigated in human papillomavirus (HPV)-associated malignancies. Because these tumors harbor a severely impaired cGAS-STING axis, but they still retain a largely functional RIG-I pathway, another critical mediator of adaptive and innate immune responses, we asked whether RIG-I activation by the 5'ppp-RNA RIG-I agonist M8 would represent a therapeutically viable option to treat HPV+ cancers. Here, we show that M8 transfection of two cervical carcinoma-derived cell lines, CaSki and HeLa, both expressing a functional RIG-I, triggers intrinsic apoptotic cell death, which is significantly reduced in RIG-I KO cells. We also demonstrate that M8 stimulation potentiates cisplatin-mediated cell killing of HPV+ cells in a RIG-I dependent manner. This combination treatment is equally effective in reducing tumor growth in a syngeneic pre-clinical mouse model of HPV16-driven cancer, where enhanced expression of lymphocyte-recruiting chemokines and cytokines correlated with an increased number of activated natural killer (NK) cells in the tumor microenvironment. Consistent with a role of RIG-I signaling in immunogenic cell killing, stimulation of NK cells with conditioned medium from M8-transfected CaSki boosted NK cell proliferation, activation, and migration in a RIG-I-dependent tumor cell-intrinsic manner. Given the highly conserved molecular mechanisms of carcinogenesis and genomic features of HPV-driven cancers and the remarkably improved prognosis for HPV+ oropharyngeal cancer, targeting RIG-I may represent an effective immunotherapeutic strategy in this setting, favoring the development of de-escalating strategies.

Recent Updates on Viral Oncogenesis: Available Preventive and Therapeutic Entities

Human viral oncogenesis is a complex phenomenon and a major contributor to the global cancer burden. Several recent findings revealed cellular and molecular pathways that promote the development and initiation of malignancy when viruses cause an infection. Even, antiviral treatment has become an approach to eliminate the viral infections and prevent the activation of oncogenesis. Therefore, for a better understanding, the molecular pathogenesis of various oncogenic viruses like, hepatitis virus, human immunodeficiency viral (HIV), human papillomavirus (HPV), herpes simplex virus (HSV), and Epstein-Barr virus (EBV), could be explored, especially, to expand many potent antivirals that may escalate the apoptosis of infected malignant cells while sparing normal and healthy ones. Moreover, contemporary therapies, such as engineered antibodies antiviral agents targeting signaling pathways and cell biomarkers, could inhibit viral oncogenesis. This review elaborates the recent advancements in both natural and synthetic antivirals to control viral oncogenesis. The study also highlights the challenges and future perspectives of using antivirals in viral oncogenesis.

HPV16 Impacts NHERF2 Expression in Oropharyngeal Cancers

Infection with human papillomaviruses (HPVs), in particular with HPV type 16, is now considered to be a key risk factor for the development of a subset of oropharyngeal squamous cell carcinomas (OPSCC) that show different epidemiological, clinical, and prognostic characteristics from HPV-negative (HPV-) OPSCCs. So far, extensive research efforts aiming to distinguish these two distinct entities have not identified specific biomarkers, nor led to different therapies. Previous research has shown that HPV16 E6 oncoprotein binds NHERF2, inducing its proteasomal degradation, and consequently increasing cell proliferation; we therefore aimed to investigate how this might be reflected in human histological samples. We analyzed NHERF2 expression patterns in HPV16-positive (HPV16+) and HPV- OPSCC samples, to investigate any potential differences in NHERF2 pattern. Interestingly, we observed a statistically significant decrease in NHERF2 levels in HPV16+ and poorly differentiated HPV- OPSCCs, compared with healthy tissue. Furthermore, we observed a significant reduction in the percentage of NHERF2 immunoreactive cancer cells in HPV16+ tumors, compared with well and moderately differentiated HPV- OPSCCs, suggesting the importance of 16E6's targeting of NHERF2 in HPV-driven oncogenesis in the head and neck area.

Four conserved amino acids on human papillomavirus E6 predict clinical high-risk types

Human papillomavirus (HPV) types included in the genus alpha papillomavirus (alpha-HPVs) are subdivided into high- and low-risk HPVs associated with tumorigenicity. According to conventional risk classification, over 30 alpha-HPVs remain unclassified and HPV groups phylogenetically classified using the L1 gene do not exactly correspond to the conventional risk classification groups. Here, we propose a novel cervical lesion progression risk classification strategy. Using four E6 risk distinguishable amino acids (E6-RDAAs), we successfully expanded the conventional classification to encompass alpha-HPVs and resolve discrepancies. We validated our classification system using alpha-HPV-targeted sequence data of 325 cervical swab specimens from participants in Japan. Clinical outcomes significantly correlated with the E6-RDAA classification. Four of five HPV types in the data set that were not conventionally classified (HPV30, 34, 67, and 69) were high-risk according to our classification criteria. This report sheds light on the carcinogenicity of rare genital HPV types using a novel risk classification strategy.

Crystal Structures of Plk1 Polo-Box Domain Bound to the Human Papillomavirus Minor Capsid Protein L2-Derived Peptide

Human papillomaviruses (HPVs) can increase the proliferation of infected cells during HPV-driven abnormalities, such as cervical cancer or benign warts. To date, more than 200 HPV genotypes have been identified, most of which are classified into three major genera: Alphapapillomavirus, Betapapillomavirus, and Gammapapillomavirus. HPV genomes commonly encode two structural (L1 and L2) and seven functional (E1, E2, E4-E7, and E8) proteins. L2, the minor structural protein of HPVs, not only serves as a viral capsid component but also interacts with various human proteins during viral infection. A recent report revealed that L2 of HPV16 recruits polo-like kinase 1 (Plk1), a master regulator of eukaryotic mitosis and cell cycle progression, for the delivery of viral DNA to mitotic chromatin during HPV16 infection. In this study, we verified the direct and potent interactions between the polo-box domain (PBD) of Plk1 and PBD-binding motif (S-S-pT-P)-containing phosphopeptides derived from L2 of HPV16/HPV18 (high-risk alphapapillomaviruses), HPV5b (low-risk betapapillomavirus), and HPV4 (low-risk gammapapillomavirus). Subsequent structural determination of the Plk1 PBD bound to the HPV18 or HPV4 L2-derived phosphopeptide demonstrated that they interact with each other in a canonical manner, in which electrostatic interactions and hydrogen bonds play key roles in sustaining the complex. Therefore, our structural and biochemical data imply that Plk1 is a broad binding target of L2 of various HPV genotypes belonging to the Alpha-, Beta-, and Gammapapillomavirus genera.

Evidence for direct interaction between the oncogenic proteins E6 and E7 of high-risk human papillomavirus (HPV)

Human papillomaviruses (HPVs) are DNA tumor viruses that infect mucosal and cutaneous epithelial cells of more than 20 vertebrates. High-risk HPV causes about 5% of human cancers worldwide, and the viral proteins E6 and E7 promote carcinogenesis by interacting with tumor suppressors and interfering with many cellular pathways. As a consequence, they immortalize cells more efficiently in concert than individually. So far, the networks of E6 and E7 with their respective cellular targets have been studied extensively but independently. However, we hypothesized that E6 and E7 might also interact directly with each other in a novel interaction affecting HPV-related carcinogenesis. Here, we report a direct interaction between E6 and E7 proteins from carcinogenic HPV types 16 and 31. We demonstrated this interaction via cellular assays using two orthogonal methods: coimmunoprecipitation and flow cytometry-based FRET assays. Analytical ultracentrifugation of the recombinant proteins revealed that the stoichiometry of the E6/E7 complex involves two E7 molecules and two E6 molecules. In addition, fluorescence polarization showed that (I) E6 binds to E7 with a similar affinity for HPV16 and HPV31 (in the same micromolar range) and (II) that the binding interface involves the unstructured N-terminal region of E7. The direct interaction of these highly conserved papillomaviral oncoproteins may provide a new perspective for studying HPV-associated carcinogenesis and the overall viral life cycle.

PI3K/AKT/mTOR Signaling Pathway in HPV-Driven Head and Neck Carcinogenesis: Therapeutic Implications

High-risk human papillomaviruses (HR-HPVs) are the causal agents of cervical, anogenital and a subset of head and neck carcinomas (HNCs). Indeed, oropharyngeal cancers are a type of HNC highly associated with HR-HPV infections and constitute a specific clinical entity. The oncogenic mechanism of HR-HPV involves E6/E7 oncoprotein overexpression for promoting cell immortalization and transformation, through the downregulation of p53 and pRB tumor suppressor proteins, among other cellular targets. Additionally, E6/E7 proteins are involved in promoting PI3K/AKT/mTOR signaling pathway alterations. In this review, we address the relationship between HR-HPV and PI3K/AKT/mTOR signaling pathway activation in HNC with an emphasis on its therapeutic importance.

HPV16 E6 and E7 Oncoproteins Stimulate the Glutamine Pathway Maintaining Cell Proliferation in a SNAT1-Dependent Fashion

Persistent high-risk human papillomavirus infection is the main risk factor for cervical cancer establishment, where the viral oncogenes E6 and E7 promote a cancerous phenotype. Metabolic reprogramming in cancer involves alterations in glutamine metabolism, also named glutaminolysis, to provide energy for supporting cancer processes including migration, proliferation, and production of reactive oxygen species, among others. The aim of this work was to analyze the effect of HPV16 E6 and E7 oncoproteins on the regulation of glutaminolysis and its contribution to cell proliferation. We found that the E6 and E7 oncoproteins exacerbate cell proliferation in a glutamine-dependent manner. Both oncoproteins increased the levels of transporter SNAT1, as well as GLS2 and GS enzymes; E6 also increased LAT1 transporter protein levels, while E7 increased ASCT2 and xCT. Some of these alterations are also regulated at a transcriptional level. Consistently, the amount of SNAT1 protein decreased in Ca Ski cells when E6 and E7 expression was knocked down. In addition, we demonstrated that cell proliferation was partially dependent on SNAT1 in the presence of glutamine. Interestingly, SNAT1 expression was higher in cervical cancer compared with normal cervical cells. The high expression of SNAT1 was associated with poor overall survival of cervical cancer patients. Our results indicate that HPV oncoproteins exacerbate glutaminolysis supporting the malignant phenotype.

High-Risk Human Papillomavirus Infection in Lung Cancer: Mechanisms and Perspectives

Lung cancer is a very prevalent and heterogeneous group of malignancies, and most of them are etiologically associated with tobacco smoking. However, viral infections have been detected in lung carcinomas, with high-risk human papillomaviruses (HR-HPVs) being among them. The role of HR-HPVs in lung cancer has been considered to be controversial. This issue is due to the highly variable presence of this virus in lung carcinomas worldwide, and the low viral load frequently that is detected. In this review, we address the epidemiological and mechanistic findings regarding the role of HR-HPVs in lung cancer. Some mechanisms of HR-HPV-mediated lung carcinogenesis have been proposed, including (i) HPV works as an independent carcinogen in non-smoker subjects; (ii) HPV cooperates with carcinogenic compounds present in tobacco smoke; (iii) HPV promotes initial alterations being after cleared by the immune system through a "hit and run" mechanism. Additional research is warranted to clarify the role of HPV in lung cancer.

Description of CRISPR-Cas9 development and its prospects in human papillomavirus-driven cancer treatment

Human papillomaviruses (HPVs) have been recognized as the etiologic agents of various cancers and are called HPV-driven cancers. Concerning HPV-mediated carcinogenic action, gene therapy can cure cancer at the molecular level by means of the correction of specific genes or sites. CRISPR-Cas9, as a novel genetic editing technique, can correct errors in the genome and change the gene expression and function in cells efficiently, quickly, and with relative ease. Herein, we overviewed studies of CRISPR-mediated gene remedies for HPV-driven cancers and summarized the potential applications of CRISPR-Cas9 in gene therapy for cancer.

HPV-18E6 Inhibits Interactions between TANC2 and SNX27 in a PBM-Dependent Manner and Promotes Increased Cell Proliferation

While a great deal is known about the role of the E6 PDZ binding motif (PBM) in modulating the cellular proteins involved in regulating cell polarity, much less is known about the consequences of E6's interactions with SNX27 and the endocytic sorting machinery. We reasoned that a potential consequence of such interactions could be to affect the fate of multiple SNX27 endosomal partners, such as transmembrane proteins or soluble accessory proteins.

The Effectiveness of Therapeutic Vaccines for the Treatment of Cervical Intraepithelial Neoplasia 3: A Systematic Review and Meta-Analysis

Cervical cancer (CC) is a disease that affects many women worldwide, especially in low-income countries. The human papilloma virus (HPV) is the main causative agent of this disease, with the E6 and E7 oncoproteins being responsible for the development and maintenance of transformed status. In addition, HPV is also responsible for the appearance of cervical intraepithelial neoplasia (CIN), a pre-neoplastic condition burdened by very high costs for its screening and therapy. So far, only prophylactic vaccines have been approved by regulatory agencies as a means of CC prevention. However, these vaccines cannot treat HPV-positive women. A search was conducted in several databases (PubMed, Scopus, Web of Science, and ClinicalTrials.gov) to systematically identify clinical trials involving therapeutic vaccines against CIN 3. Histopathological regression data, immunological parameters, safety, DNA clearance, and vaccine efficacy were considered from each selected study, and from the 102 articles found, 8 were selected based on the defined inclusion criteria. Histopathological regression from CIN 3 to CIN < 1 was 22.1% (95% CI: 0.627−0.967; p-value = 0.024), showing a vaccine efficacy of 23.6% (95% CI; 0.666−0.876; p-value < 0.001). DNA clearance was assessed, and the risk of persistent HPV DNA was 23.2% (95% CI: 0.667−0.885; p-value < 0.001). Regarding immunological parameters, immune responses by specific T-HPV cells were more likely in vaccinated women (95% CI: 1.245−9.162; p-value = 0.017). In short, these studies favored the vaccine group over the placebo group. This work indicated that therapeutic vaccines are efficient in the treatment of CIN 3, even after accounting for publication bias.

Exploration of shared gene signature with development of pre-eclampsia and cervical cancer

Background: The relationship between pre-eclampsia (PE) and cervical cancer (CC) has drawn more attention recently, while little is known about the shared pathogenesis of CC and PE. In the present research, we aimed to generate the shared gene network as well as the prognostic model to reveal the development of CC and PE.

Methods: The transcription data of CC and PE patients were obtained and enrolled into weighted gene co-expression network (WGCNA) analysis. Disease-specific modules in CC and PE were determined to discover the shared genes. The expression patterns of genes at protein level were examined by HPA database. Further, LASSO penalty regression and Cox analysis were applied to create a prognostic signature based on the shared genes, with survival curves and ROC plots employed to confirm the predictive capacity. To uncover the function roles and pathways involved in signature, gene set enrichment analysis (GSEA) was conducted. Finally, the immune infiltration status in CC was depicted using CIBERSORT algorithms.

Results: WGCNA determined three hub modules between CC and PE. A total of 117 shared genes were obtained for CC and PE and mainly enriched in cell proliferation, regulation of cell development and neuron differentiation. Then, we created a robust prognostic model based on the 10 shared genes by performing stepwise Cox analyses. Our proposed model presented a favorable ability in prognosis forecast and was correlated with the infiltration of immunocytes including B cells, macrophages and T cells. GSEA disclosed that high-risk group was involved in cancer-related pathways.

Conclusion: The present project identified the shared genes to uncover the pathogenesis of CC and PE and further proposed and validated a prognostic signature to accurately forecast the clinical outcomes of CC patients.

Regulation of the Innate Immune Response during the Human Papillomavirus Life Cycle

High-risk human papillomaviruses (HR HPVs) are associated with multiple human cancers and comprise 5% of the human cancer burden. Although most infections are transient, persistent infections are a major risk factor for cancer development. The life cycle of HPV is intimately linked to epithelial differentiation. HPVs establish infection at a low copy number in the proliferating basal keratinocytes of the stratified epithelium. In contrast, the productive phase of the viral life cycle is activated upon epithelial differentiation, resulting in viral genome amplification, high levels of late gene expression, and the assembly of virions that are shed from the epithelial surface. Avoiding activation of an innate immune response during the course of infection plays a key role in promoting viral persistence as well as completion of the viral life cycle in differentiating epithelial cells. This review highlights the recent advances in our understanding of how HPVs manipulate the host cell environment, often in a type-specific manner, to suppress activation of an innate immune response to establish conditions supportive of viral replication.

Rapidly evolving viral motifs mostly target biophysically constrained binding pockets of host proteins

Evolutionary changes in host-virus interactions can alter the course of infection, but the biophysical and regulatory constraints that shape interface evolution remain largely unexplored. Here, we focus on viral mimicry of host-like motifs that allow binding to host domains and modulation of cellular pathways. We observe that motifs from unrelated viruses preferentially target conserved, widely expressed, and highly connected host proteins, enriched with regulatory and essential functions. The interface residues within these host domains are more conserved and bind a larger number of cellular proteins than similar motif-binding domains that are not known to interact with viruses. In contrast, rapidly evolving viral-binding human proteins form few interactions with other cellular proteins and display high tissue specificity, and their interfaces have few inter-residue contacts. Our results distinguish between conserved and rapidly evolving host-virus interfaces and show how various factors limit host capacity to evolve, allowing for efficient viral subversion of host machineries.

AIB1 is a novel target of the high-risk HPV E6 protein and a biomarker of cervical cancer progression

The high-risk human papillomaviruses (HPV-16, -18) are critical etiologic agents in human malignancy, most importantly in cervical cancer. These oncogenic viruses encode the E6 and E7 proteins that are uniformly retained and expressed in cervical cancers and required for maintenance of the tumorigenic phenotype. The E6 and E7 proteins were first identified as targeting the p53 and pRB tumor suppressor pathways, respectively, in host cells, thereby leading to disruption of cell cycle controls. In addition to p53 degradation, a number of other functions and critical targets for E6 have been described, including telomerase, Myc, PDZ-containing proteins, Akt, Wnt, mTORC1, as well as others. In this study, we identified Amplified in Breast Cancer 1 (AIB1) as a new E6 target. We first found that E6 and hTERT altered similar profiling of gene expression in human foreskin keratinocytes (HFK), independent of telomerase activity. Importantly, AIB1 was a common transcriptional target of both E6 and hTERT. We then verified that high-risk E6 but not low-risk E6 expression led to increases in AIB1 transcript levels by real-time RT-PCR, suggesting that AIB1 upregulation may play an important role in cancer development. Western blots demonstrated that AIB1 expression increased in HPV-16 E6 and E7 expressing (E6E7) immortalized foreskin and cervical keratinocytes, and in three of four common cervical cancer cell lines as well. Then, we evaluated the expression of AIB1 in human cervical lesions and invasive carcinoma using immunohistochemical staining. Strikingly, AIB1 showed positivity in the nucleus of cells in the immediate suprabasal epithelium, while nuclei of the basal epithelium were negative, as evident in the Cervical Intraepithelial Neoplasia 1 (CIN1) samples. As the pathological grading of cervical lesions increased from CIN1, CIN2, CIN3 carcinoma in situ and invasive carcinoma, AIB1 staining increased progressively, suggesting that AIB1 may serve as a novel histological biomarker for cervical cancer development. For cases of invasive cervical carcinoma, AIB1 staining was specific to cancerous lesions. Increased expression of AIB1 was also observed in transgenic mouse cervical neoplasia and cancer models induced by E6E7 and estrogen. Knockdown of AIB1 expression in E6E7 immortalized human cervical cells significantly abolished cell proliferation. Taken together, these data support AIB1 as a novel target of HPV E6 and a biomarker of cervical cancer progression.

Green Tea Polyphenols Cause Apoptosis and Autophagy in HPV-16 Subgene-Immortalized Human Cervical Epithelial Cells via the Activation of the Nrf2 Pathway

Infection with human papillomavirus (HPV) is relatively common and certain high-risk HPV strains can induce epithelial dysplasia, increasing the risk of cervical cancer. Green tea polyphenol (GTP) preparations exhibit diverse anti-inflammatory, antioxidative, and antitumor properties In Vitro and In Vivo. Topical GTP application has been recommended as a treatment for genital warts, but the effect of GTP treatment on HPV infection and HPV-associated cancer remains to be established. The present study aimed to explore the mechanism by which GTP affected HPV type 16 (HPV-16)-positive immortalized human cervical epithelial cells. Survival, apoptosis, and autophagocytosis of these cells following GTP treatment was assessed using CCK-8 assay, flow cytometry, and monodansylcadaverine (MDC) staining. These cells were further transfected with an shRNA specific for Nrf2 to generate stable Nrf2-knockdown cells. The levels of Caspase-3, Bcl-2, Bax, P53, Rb, HPV-16 E6, HPV-16 E7, P62, Beclin1 and LC3B were determined via Western blotting. These analyses revealed that GTP treatment induced autophagy and apoptosis in HPV-16-positive cells, while Nrf2 gene knockdown reversed GTP-induced autophagic and apoptotic effects. Together, these results suggested that GTP could alleviate HPV infection and HPV-associated precancerous lesions In Vitro by regulating the Nrf2 pathway, highlighting the therapeutic potential of GTP in treating HPV infection.

A Critical Role for p53 during the HPV16 Life Cycle

Human papillomaviruses (HPV) are causative agents in ano-genital and oral cancers; HPV16 is the most prevalent type detected in human cancers. The HPV16 E6 protein targets p53 for proteasomal degradation to facilitate proliferation of the HPV16 infected cell. However, in HPV16 immortalized cells E6 is predominantly spliced (E6*) and unable to degrade p53. Here, we demonstrate that human foreskin keratinocytes immortalized by HPV16 (HFK+HPV16), and HPV16 positive oropharyngeal cancers, retain significant expression of p53. In addition, p53 levels increase in HPV16+ head and neck cancer cell lines following treatment with cisplatin. Introduction of full-length E6 into HFK+HPV16 resulted in attenuation of cellular growth (in hTERT immortalized HFK, E6 expression promoted enhanced proliferation). An understudied interaction is that between E2 and p53 and we investigated whether this was important for the viral life cycle. We generated mutant genomes with E2 unable to interact with p53 resulting in profound phenotypes in primary HFK. The mutant induced hyper-proliferation, but an ultimate arrest of cell growth; β-galactosidase staining demonstrated increased senescence, and COMET assays showed increased DNA damage compared with HFK+HPV16 wild-type cells. There was failure of the viral life cycle in organotypic rafts with the mutant HFK resulting in premature differentiation and reduced proliferation. The results demonstrate that p53 expression is critical during the HPV16 life cycle, and that this may be due to a functional interaction between E2 and p53. Disruption of this interaction has antiviral potential. IMPORTANCE Human papillomaviruses are causative agents in around 5% of all cancers. There are currently no antivirals available to combat these infections and cancers, therefore it remains a priority to enhance our understanding of the HPV life cycle. Here, we demonstrate that an interaction between the viral replication/transcription/segregation factor E2 and the tumor suppressor p53 is critical for the HPV16 life cycle. HPV16 immortalized cells retain significant expression of p53, and the critical role for the E2-p53 interaction demonstrates why this is the case. If the E2-p53 interaction is disrupted then HPV16 immortalized cells fail to proliferate, have enhanced DNA damage and senescence, and there is premature differentiation during the viral life cycle. Results suggest that targeting the E2-p53 interaction would have therapeutic benefits, potentially attenuating the spread of HPV16.

Taxifolin and Lucidin as Potential E6 Protein Inhibitors: p53 Function Re-Establishment and Apoptosis Induction in Cervical Cancer Cells

Simple Summary

Human papillomavirus (HPV)-related cancers continue to be a major medical concern, and there exists an urgent need to improve the current therapeutic approaches by combining strategies or proposing new compounds to offer more specific and less invasive treatments. The aim of this work was to discover potential inhibitors of the E6/E6AP/p53 complex formation. We started this work with an initial in silico approach including molecular docking and molecular dynamics simulations, and these tools allowed us to select potential inhibitors, using E6 protein as a target. In addition, we found that lucidin and taxifolin were able to selectively decrease the viability of HPV-positive cells to re-establish p53 protein levels and to induce apoptosis. These findings represent a promising starting point for the development of anti-HPV drugs.

Abstract

Cervical cancer is the fourth leading cause of death in women worldwide, with 99% of cases associated with a human papillomavirus (HPV) infection. Given that HPV prophylactic vaccines do not exert a therapeutic effect in individuals previously infected, have low coverage of all HPV types, and have poor accessibility in developing countries, it is unlikely that HPV-associated cancers will be eradicated in the coming years. Therefore, there is an emerging need for the development of anti-HPV drugs. Considering HPV E6’s oncogenic role, this protein has been proposed as a relevant target for cancer treatment. In the present work, we employed in silico tools to discover potential E6 inhibitors, as well as biochemical and cellular assays to understand the action of selected compounds in HPV-positive cells (Caski and HeLa) vs. HPV-negative (C33A) and non-carcinogenic (NHEK) cell lines. In fact, by molecular docking and molecular dynamics simulations, we found three phenolic compounds able to dock in the E6AP binding pocket of the E6 protein. In particular, lucidin and taxifolin were able to inhibit E6-mediated p53 degradation, selectively reduce the viability, and induce apoptosis in HPV-positive cells. Altogether, our data can be relevant for discovering promising leads for the development of specific anti-HPV drugs.

Human Papillomavirus Detected in Oropharyngeal Cancers from Chilean Subjects

High-risk human papillomaviruses (HR-HPV) are the causal agents of an important subset of oropharyngeal cancers that has increased considerably in incidence in recent years. In this study, we evaluated the presence of HPV in 49 oropharyngeal cancers from Chilean subjects. The presence of HPV DNA was analyzed by conventional PCR, the genotypes were identified through sequencing, and the expression of E6/E7 transcripts was evaluated by a reverse transcriptase polymerase chain reaction (RT-PCR). Additionally, to determine p16 expression—a surrogate marker for oncogenic HPV infection—a tissue array was constructed for immunohistochemistry (IHC). HPV was detected in 61.2% of oropharyngeal carcinomas, the most prevalent genotype being HPV16 (80%). E6 and E7 transcripts were detected in 91.6% and 79.1% of the HPV16-positive specimens, respectively, demonstrating functional HPV infections. Furthermore, p16 expression was positive in 58.3% of cases. These findings show a high prevalence of HR-HPV in oropharyngeal tumors from Chile, suggesting the necessity of additional studies to address this growing public health concern.

Long-read sequencing unveils high-resolution HPV integration and its oncogenic progression in cervical cancer

Integration of human papillomavirus (HPV) DNA into the human genome is considered as a key event in cervical carcinogenesis. Here, we perform comprehensive characterization of large-range virus-human integration events in 16 HPV16-positive cervical tumors using the Nanopore long-read sequencing technology. Four distinct integration types characterized by the integrated HPV DNA segments are identified with Type B being particularly notable as lacking E6/E7 genes. We further demonstrate that multiple clonal integration events are involved in the use of shared breakpoints, the induction of inter-chromosomal translocations and the formation of extrachromosomal circular virus-human hybrid structures. Combined with the corresponding RNA-seq data, we highlight LINC00290, LINC02500 and LENG9 as potential driver genes in cervical cancer. Finally, we reveal the spatial relationship of HPV integration and its various structural variations as well as their functional consequences in cervical cancer. These findings provide insight into HPV integration and its oncogenic progression in cervical cancer.

The molecular mechanisms underlying cervical carcinogenesis following integration of HPV DNA into the human genome remain elusive. Here, the authors perform long-read sequencing in 16 HPV16-positive cervical tumors and identify distinct integration types, structural variations and potential driver genes.

Like Brothers in Arms: How Hormonal Stimuli and Changes in the Metabolism Signaling Cooperate, Leading HPV Infection to Drive the Onset of Cervical Cancer

Despite all precautionary actions and the possibility of using vaccinations to counteract infections caused by human papillomaviruses (HPVs), HPV-related cancers still account for approximately 5% of all carcinomas. Worldwide, many women are still excluded from adequate health care due to their social position and origin. Therefore, immense efforts in research and therapy are still required to counteract the challenges that this disease entails. The special thing about an HPV infection is that it is not only able to trick the immune system in a sophisticated way, but also, through genetic integration into the host genome, to use all the resources available to the host cells to complete the replication cycle of the virus without activating the alarm mechanisms of immune recognition and elimination. The mechanisms utilized by the virus are the metabolic, immune, and hormonal signaling pathways that it manipulates. Since the virus is dependent on replication enzymes of the host cells, it also intervenes in the cell cycle of the differentiating keratinocytes and shifts their terminal differentiation to the uppermost layers of the squamocolumnar transformation zone (TZ) of the cervix. The individual signaling pathways are closely related and equally important not only for the successful replication of the virus but also for the onset of cervical cancer. We will therefore analyze the effects of HPV infection on metabolic signaling, as well as changes in hormonal and immune signaling in the tumor and its microenvironment to understand how each level of signaling interacts to promote tumorigenesis of cervical cancer.

Sensitive Electrochemiluminescence Biosensor Based on the Target Trigger Difference of the Electrostatic Interaction between an ECL Reporter and the Electrode Surface

The discrepancy of the electrostatic interaction of negatively charged signal molecules to long and short DNA strands of the modified electrode surface has been used for the first time to the develop an electrochemiluminescence (ECL) biosensor for human papillomavirus 16 (HPV 16) DNA detection. The short single-stranded capture probe (CP) was modified first on the surface of the gold electrode, which only has a small amount of negative charge. The electrostatic interaction between the negatively charged tris(2,2'-bipyridyl) ruthenium(II) chloride hexahydrate-doped SiO₂ nanoparticles (Ru@SiO₂ NPs) and CP is weak, hence Ru@SiO₂ NPs easily diffuse to the surface of the electrode to generate a strong ECL signal. Hybrid chain reaction (HCR) amplification products (long strand dsDNA) were prepared in homogeneous solution in advance. When the target was present, the dsDNA can be connected on the electrode surface and cause the enhancement of the negative charge on the electrode surface. Owing to electrostatic interaction and steric hindrance, Ru@SiO₂ NPs are difficult to diffuse to the electrode surface, resulting in a significantly reduced ECL signal. The decrease of ECL signal is linearly correlated with the logarithm of the HPV concentration under optimal conditions, with the detection range being 0.1 fM -5 pM with a limit of 1.41 aM. This innovative methodology expands the application of electrostatic interaction in ECL sensing, but can also easily develop biosensors for detecting other targets by changing the DNA sequence used in this strategy.

DNA image cytometry parameters to identify high-grade cervical lesions

OBJECTIVE

Evaluate the performance of different DNA image cytometry (DNA-ICM) ploidy parameters to categorize a DNA-ICM result, and consequently identify high-grade cervical intraepithelial neoplasia or worse (≥CIN2).

METHODS

Cervical samples from 232 women were collected for DNA-ICM analysis and biopsy confirmation. Five DNA parameters were used to define DNA aneuploidy: number of cells with exceeding events (EE) over 2.5cEE, 4cEE, 5cEE, 9cEE, and aneuploid stemlines. DNA-ICM results were categorized as normal, suspicious, and abnormal.

RESULTS

For individual DNA ploidy parameters, sensitivity for 50 cells with 2.5cEE, 45 cells with 4cEE, 1 cell with 9cEE and aneuploid stemline were 72.95%. 54.1%, 69.67% and 54.1%, while specificity were 80.0%, 90.0%, 89.09% and 95.45%, respectively. For 5cEE parameter, sensitivity for 1, 2, 3, 4 and 5 cells were 93.44%, 85.25%, 81.97%, 77.87% and 75.41%, while specificity were 46.36%, 63.64%, 74.55%, 76.36% and 80.91%, respectively. For categorized DNA-ICM results, a suspicious result revealed superior sensitivity to an abnormal result (87.70% vs 82.79%, P = 0.031), but inferior specificity (54.55% vs 75.45%, P <0.001). Both DNA-ICM results were statistically different from a normal result (P <0.05).

CONCLUSION

For prognostic purposes 1 cell with 9cEE, 45 cells with 4cEE and aneuploid stemline are the best parameters to categorize an abnormal DNA-ICM result, followed by 50 cells with 2.5cEE and 4 cells with 5cEE. For screening purposes, 10 cells with 2.5cEE, 10 cells with 4cEE, and 2 cells with 5cEE are suitable parameters to categorize a suspicious DNA-ICM result.

Dual Role of YY1 in HPV Life Cycle and Cervical Cancer Development

Human papillomaviruses (HPVs) are considered to be key etiological agents responsible for the induction and development of cervical cancer. However, it has been suggested that HPV infection alone may not be sufficient to promote cervical carcinogenesis, and other unknown factors might be required to establish the disease. One of the suggested proteins whose deregulation has been linked with oncogenesis is transcription factor Yin Yang 1 (YY1). YY1 is a multifunctional protein that is involved not only in the regulation of gene transcription and protein modification, but can also control important cell signaling pathways, such as cell growth, development, differentiation, and apoptosis. Vital functions of YY1 also indicate that the protein could be involved in tumorigenesis. The overexpression of this protein has been observed in different tumors, and its level has been correlated with poor prognoses of many types of cancers. YY1 can also regulate the transcription of viral genes. It has been documented that YY1 can bind to the HPV long control region and regulate the expression of viral oncogenes E6 and E7; however, its role in the HPV life cycle and cervical cancer development is different. In this review, we explore the role of YY1 in regulating the expression of cellular and viral genes and subsequently investigate how these changes inadvertently contribute toward the development of cervical malignancy.

Association between ТР53, MDM2 and NQO1 gene polymorphisms and viral load among women with human papillomavirus

The risk of cervical cancer is caused by persistent human papillomavirus (HPV) infection. Cervical cancer is the most frequent cancer among women. Our purpose was to investigate the association between TP53 215C>G (Pro72Arg), MDM2 -410T>G, and NQO1 609C>T gene polymorphisms with a high HPV load and the inf luence of gene-gene interactions on prolonged HPV infection. Eighty-nine women with a high HPV viral load and 114 healthy women were involved in a case–control study. Genotyping for TP53 215C>G (Pro72Arg) and MDM2 -410T>G SNPs was carried out by allele-specif ic PCR and genotyping for NQO1 609C>T was performed by a TaqMan assay. Quantitative analysis of HPV DNA was performed by AmpliSens® HPV HCR screen-titer-FRT test system. Gene-gene interactions were analyzed using the multifactor dimensionality reduction (MDR) method. The study of separate SNPs of MDM2 -410T>G and NQO1 609C>T genes did not reveal any statistically signif icant difference in genotype and allele frequencies among women within the two groups. The frequency of the 215G (72Arg) allele and 215GG (72Arg/ Arg) genotype of the TP53 gene was signif icantly higher in the case group than in the control group (OR = 1.74, 95 % CI = 1.10–2.73; p = 0.02 and OR = 1.97, 95 % CI = 1.13–3.46; p = 0.04, respectively). MDR analysis showed the signif icance of intergenic interactions of the three studied loci TP53 (rs1042522) – MDM2 (rs2279744) – NQO1 (rs1800566) for the formation of a high HPV load (OR = 3.05, 95 % CI = 1.73–5.46; p = 0.0001).

HPV-associated oropharyngeal cancer: epidemiology, molecular biology and clinical management

Human papillomavirus (HPV)-positive (HPV⁺) oropharyngeal squamous cell carcinoma (OPSCC) has one of the most rapidly increasing incidences of any cancer in high-income countries. The most recent (8th) edition of the UICC/AJCC staging system separates HPV⁺ OPSCC from its HPV-negative (HPV⁻) counterpart to account for the improved prognosis seen in the former. Indeed, owing to its improved prognosis and greater prevalence in younger individuals, numerous ongoing trials are examining the potential for treatment de-intensification as a means to improve quality of life while maintaining acceptable survival outcomes. In addition, owing to the distinct biology of HPV⁺ OPSCCs, targeted therapies and immunotherapies have become an area of particular interest. Importantly, OPSCC is often detected at an advanced stage owing to a lack of symptoms in the early stages; therefore, a need exists to identify and validate possible diagnostic biomarkers to aid in earlier detection. In this Review, we provide a summary of the epidemiology, molecular biology and clinical management of HPV⁺ OPSCC in an effort to highlight important advances in the field. Ultimately, a need exists for improved understanding of the molecular basis and clinical course of this disease to guide efforts towards early detection and precision care, and to improve patient outcomes.

The incidence of human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) is increasing rapidly in most developed countries. In this Review, the authors provide an overview of the epidemiology, molecular biology and treatment of HPV-positive OPSCC, including discussions of the role of treatment de-escalation and emerging novel therapies.

The incidence of human papillomavirus-associated oropharyngeal cancer (HPV⁺ OPSCC) is expected to continue to rise over the coming decades until the benefits of gender-neutral prophylactic HPV vaccination begin to become manifest.

The incidence of HPV⁺ OPSCC appears to be highest in high-income countries, although more epidemiological data are needed from low- and middle-income countries, in which HPV vaccination coverage remains low.

The substantially better prognosis of patients with HPV⁺ OPSCC compared to those with HPV^– OPSCC has been recognized in the American Joint Committee on Cancer TNM8 staging guidelines, which recommend stratification by HPV status to improve staging.

The molecular biology and genomic features of HPV⁺ OPSCC are similar to those of other HPV-associated malignancies, with HPV oncogenes (E6 and E7) acting as key drivers of pathogenesis.

Treatment de-intensification is being pursued in clinical trials, although identifying the ~15% of patients with HPV⁺ OPSCC who have recurrent disease, and who therefore require more intensive treatment, remains a key challenge.

Structural and biochemical analysis of the PTPN4 PDZ domain bound to the C-terminal tail of the human papillomavirus E6 oncoprotein

High-risk genotypes of human papillomaviruses (HPVs) are directly implicated in various abnormalities associated with cellular hyperproliferation, including cervical cancer. E6 is one of two oncoproteins encoded in the HPV genome, which recruits diverse PSD-95/Dlg/ZO-1 (PDZ) domain-containing human proteins through its C-terminal PDZ-binding motif (PBM) to be degraded by means of the proteasome pathway. Among the three PDZ domain-containing protein tyrosine phosphatases, protein tyrosine phosphatase non-receptor type 3 (PTPN3) and PTPN13 were identified to be recognized by HPV E6 in a PBM-dependent manner. However, whether HPV E6 associates with PTPN4, which also has a PDZ domain and functions as an apoptosis regulator, remains undetermined. Herein, we present structural and biochemical evidence demonstrating the direct interaction between the PBM of HPV16 E6 and the PDZ domain of human PTPN4 for the first time. X-ray crystallographic structure determination and binding measurements using isothermal titration calorimetry demonstrated that hydrophobic interactions in which Leu158 of HPV16 E6 plays a key role and a network of intermolecular hydrogen bonds sustain the complex formation between PTPN4 PDZ and the PBM of HPV16 E6. In addition, it was verified that the corresponding motifs from several other high-risk HPV genotypes, including HPV18, HPV31, HPV33, and HPV45, bind to PTPN4 PDZ with comparable affinities, suggesting that PTPN4 is a common target of various pathogenic HPV genotypes.

Long noncoding RNA SNHG3 promotes malignant phenotypes in cervical cancer cells via association with YAP1

Long non-coding RNA (LncRNA) Small Nucleolar RNA Host Gene 3 (SNHG3) is involved in the occurrence and development of various cancers. However, the exact function and mechanism of SNHG3 in cervical cancer (CC) are still unclear. In this context, we identified a significant increase of SNHG3 expression in CC tissues. Upregulation of SNHG3 expression was associated with advanced FIGO stage and metastasis, and indicated poor overall survival of the CC patients. Functionally, SNHG3 enhanced the proliferation, migration and invasion of CC cells in vitro, and facilitated CC growth in vivo. Further investigation uncovered that SNHG3 interacted with oncoprotein YAP1, thus suppressing its degradation. Additionally, SNHG3 modulated the transcription of several target genes of YAP1. The oncogenic role of SNHG3 was partially attributable to YAP1. Taken together, our research revealed the prognostic and functional roles for SNHG3 in CC, suggesting that SNHG3 could serve as a biomarker for prognosis and a therapeutic target for CC.

Human papillomaviruses: diversity, infection and host interactions

Human papillomaviruses (HPVs) are an ancient and highly successful group of viruses that have co-evolved with their host to replicate in specific anatomical niches of the stratified epithelia. They replicate persistently in dividing cells, hijack key host cellular processes to manipulate the cellular environment and escape immune detection, and produce virions in terminally differentiated cells that are shed from the host. Some HPVs cause benign, proliferative lesions on the skin and mucosa, and others are associated with the development of cancer. However, most HPVs cause infections that are asymptomatic and inapparent unless the immune system becomes compromised. To date, the genomes of almost 450 distinct HPV types have been isolated and sequenced. In this Review, I explore the diversity, evolution, infectious cycle, host interactions and disease association of HPVs.

Usefulness of E7 mRNA in HPV16-Positive Women to Predict the Risk of Progression to HSIL/CIN2

Objective: To evaluate whether E7 mRNA can predict the risk of progression in women with HPV16 infection. Design: A prospective observational study. Setting: A tertiary university hospital. Population: A cohort of 139 women referred to colposcopy for an abnormal screening result fulfilling the following inclusion criteria: (1) a positive test result confirming HPV16 infection; (2) a biopsy sample with a histological diagnosis of an absence of lesion or low-grade SIL/CIN grade1 (LSIL/CIN1); (3) no previous HPV vaccination; (4) no pregnancy; and (5) no previous cervical treatments; and (6) no immunosuppression. Methods: At the first visit, all women underwent a cervical sample for liquid-based cytology, HPV testing and genotyping, and HPV16 E7 mRNA analysis and a colposcopy with at least one colposcopy-guided biopsy. Follow-up visits were scheduled every six months. In each control, a liquid-based Pap smear, HPV testing, as well as a colposcopy examination with biopsy if necessary were performed. Main outcome measures: Histological diagnosis of HSIL/CIN2+ at any time during follow-up. Results: E7 mRNA expression was positive in 55/127 (43.3%) women included in the study and seven (12.7%) progressed to HSIL/CIN2+. In contrast, only 1/72 (1.4%) women with no HPV16 E7 mRNA expression progressed (p = 0.027). HPV16 E7 mRNA expression was associated with a 10-fold increased risk of progression (HR 10.0; 95% CI 1.2–81.4). Conclusions: HPV16 E7 mRNA could be useful for risk stratification of women with HPV16 infection in whom a HSIL/CIN2+ has been ruled out. Funding: Instituto de Salud Carlos III (ICSIII)-Fondo de Investigación Sanitaria and ERDF ‘One Way to Europe’ (PI17/00772).

Gene Targeting of HPV18 E6 and E7 Synchronously by Nonviral Transfection of CRISPR/Cas9 System in Cervical Cancer

High-risk human papillomavirus (HPV) E6 and E7 genes display vital oncogenic properties in cervical cancer. Eliminating HPV driver gene or loss of function by the clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 system is a promising treatment for the HPV-associated cancer. Thus, this study designed a CRISPR/Cas9 system to target the E6 and E7 genes at once, to detect whether it have efficacy in vitro and in vivo. Meanwhile, CRISPR/Cas9 system was measured after transfection with liposomes but virus. Cervical cancer lines (HeLa and SiHa) were used in this study. Sanger sequencing confirmed that the single CRISPR/Cas9 vector [termed E6E7-knockout (KO)] containing guide RNAs could targeting both HPV18 E6 and E7 genes in vitro. In addition, double-targeting E6 and E7 increased p53 protein expression significantly while compared with E6 or E7 targeting, respectively. Mice with xenografts were divided into four groups: three doses of experimental groups (20, 40, and 60 μg) and one control group. The E6E7-KO through liposome delivery was injected into tumors. Tumor growth was measured and protein expression was observed through immunohistochemistry. The toxic side effects in vivo were also evaluated. E6E7-KO induced cell apoptosis and inhibited cell proliferation markedly in vitro. E6E7-KO downregulated the messenger RNA and protein expression of E6 and E7, whereas p53 and p21 protein levels were upregulated accordingly. Notably, E6E7-KO delivery by liposome exhibited an effect in vivo. Tumor growth was inhibited in the E6E7-KO groups, which was accompanied by decreased E6/E7 protein expression and increased p53/p21 protein expression, especially the level of p53 protein expression. Therefore, E6E7-KO could have synergy efficient by p53 pathway. Furthermore, local injection with CRISPR/Cas9 by nonviral delivery may be regarded as a potential therapy for cervical cancer in the future.