Essential roles for soluble virion-associated heparan sulfonated proteoglycans and growth factors in human papillomavirus infections

Targeting ferroptosis for precision medicine in cervical cancer

Cervical cancer (CC) is a prevalent malignant tumor in the female reproductive system, with rising incidence rates among younger women posing a significant public health challenge. Human papillomavirus (HPV) infection is the primary cause, driving carcinogenesis by promoting abnormal proliferation of tumor cells. Ferroptosis is a form of regulated necrosis that is caused by an iron-dependent accumulation of lipid peroxides with rupture of the plasma membrane. Targeting ferroptosis-related molecules and pathways can selectively induce cervical cancer cell death, while alterations in the expression of ferroptosis-related genes provide promising biomarkers for prognostic assessment. Advances in research on biomarkers and molecular targets are improving predictions of therapeutic outcomes, overcoming drug resistance, and optimizing immunotherapy strategies, thereby opening new avenues for precision medicine. This review focuses on the molecular mechanisms underlying ferroptosis in cervical cancer, discusses its potential applications in early diagnosis and prognosis evaluation, and summarizes the latest advancements in targeted therapy, aiming to provide a novel perspective for the clinical management of cervical cancer.

Human papilloma virus (HPV) mediated cancers: an insightful update

Human papillomavirus (HPV), a DNA virus, is a well-documented causative agent of several cancers, including cervical, vulvar, vaginal, penile, anal, and head & neck cancers. Major factors contributing to HPV-related cancers include persistent infection and the oncogenic potential of particular HPV genotypes. High-risk HPV strains, particularly HPV-16 and HPV-18, are responsible for over 70% of cervical cancer cases worldwide, as well as a significant proportion of other genital and head and neck cancers. At the molecular level, the oncogenic activity of these viruses is driven by the overexpression of E6 and E7 oncoproteins. These oncoproteins dysregulate the cell cycle, inhibit apoptosis, and promote the accumulation of DNA damage, ultimately transforming normal cells into cancerous ones. This review aims to provide a comprehensive overview of the recent advances in HPV-related cancer biology and epidemiology. The review highlights the molecular pathways of HPV-driven carcinogenesis, focusing on the role of viral oncoproteins in altering host cell targets and disrupting cellular signalling pathways. The review explores the therapeutic potential of these viral proteins, and discusses current diagnostic and treatment strategies for HPV-associated cancers. Furthermore, the review highlights the critical role of HPV in the development of various malignancies, emphasizing the persistent challenges in combating these cancers despite advancements in vaccination and therapeutic strategies. We also emphasize recent breakthroughs in utilizing biomarkers to monitor cancer therapy responses, such as mRNAs, miRNAs, lncRNAs, proteins, and genetic markers. We hope this review will serve as a valuable resource for researchers working on HPV, providing insights that can guide future investigations into this complex virus, which continues to be a major contributor to global morbidity and mortality.

Human Papillomavirus Type 16 Stimulates WAVE1- and WAVE2-Dependent Actin Protrusions for Endocytic Entry

Human papillomavirus type 16 (HPV16) is an etiological agent of human cancers that requires endocytosis to initiate infection. HPV16 entry into epithelial cells occurs through a non-canonical endocytic pathway that is actin-driven, but it is not well understood how HPV16-cell surface interactions trigger actin reorganization in a way that facilitates entry. This study provides evidence that Wiskott-Aldrich syndrome protein family verprolin-homologous proteins 1 and 2 (WAVE1 and WAVE2) are molecular mediators of actin protrusions that occur at the cellular surface upon HPV addition to cells, and that this stimulation is a key step prior to endocytosis and intracellular trafficking. We demonstrate through post-transcriptional gene silencing and genome editing that WAVE1 and WAVE2 are critical for efficient HPV16 infection, and that restoration of each in knockout cells rescues HPV16 infection. Cells lacking WAVE1, WAVE2, or both internalize HPV16 at a significantly reduced rate. Microscopic analysis of fluorescently labeled cells revealed that HPV16, WAVE1, WAVE2, and actin are all colocalized at the cellular dorsal surface within a timeframe that precedes endocytosis. Within that same timeframe, we also found that HPV16-treated cells express cellular dorsal surface filopodia, which does not occur in cells lacking WAVE1 and WAVE2. Taken together, this study provides evidence that WAVE1 and WAVE2 mediate a key step prior to HPV entry into cells that involves actin reorganization in the form of cellular dorsal surface protrusions.

Sexually transmitted human papillomavirus and related sequelae

SUMMARYMore than 40 types of sexually transmitted human papillomavirus (HPV) infect the oropharyngeal and anogenital mucosa-high-risk types are associated with precancerous and cancerous lesions of the cervix, vagina, vulva, penis, anus, and oropharynx, and low-risk types cause non-malignant disease, such as anogenital warts. Though most HPV infections resolve spontaneously, immunodeficiencies may result in persistent infection and increased risk of HPV-related sequelae. The mechanism by which HPV results in malignant transformation is multifaceted, involving interactions with numerous cellular pathways, the host immune system, and potentially the host microbiome. Vaccination against HPV is highly efficacious in the prevention of infection and related sequelae, and there now exist several approved formulations that protect against both high- and low-risk types. Despite the advent of vaccination, early detection and treatment of cervical and anal precancerous lesions continues to be integral to secondary prevention-molecular HPV testing, cytology, and tissue biopsy allow for triaging of patients, after which appropriate treatment with close follow-up can avert cancer development.

HSPG-binding peptide Pep19-2.5 is a potent inhibitor of HPV16 infection

Peptide-based therapeutics are gaining attention for their potential to target various viral and host cell factors. One notable example is Pep19-2.5 (Aspidasept), a synthetic anti-lipopolysaccharide peptide that binds to heparan sulfate proteoglycans (HSPGs) and has demonstrated inhibitory effects against certain bacteria and enveloped viruses. This study explores, for the first time, the effectiveness of Pep19-2.5 against a non-enveloped virus, using pseudoviruses of the oncogenic human papillomavirus type 16 (HPV16) as a model. HPV16 infects epithelial cells of the skin and mucosa by using multiple cell surface receptors with initial attachment to HSPGs. Pharmacological inhibition with Pep19-2.5 in HeLa and HaCaT cells resulted in a concentration-dependent reduction of HPV16 PsV infection, with near-complete blockade observed at higher concentrations. The half-maximal inhibitory concentration (IC50) was determined to be 116 nM in HeLa cells and 183 nM in HaCaT cells, highlighting its potent antiviral activity. Our results demonstrate that Pep19-2.5 not only inhibits HPV16 PsV binding to the cell surface but also significantly reduces infection when administered post-binding. Imaging analyses revealed Pep19-2.5-dependent release of large cell-associated crowds of viral particles, suggesting interference with the transfer to secondary receptor molecules. This was corroborated by the effectiveness of Pep19-2.5 in an HSPG-negative cell line, indicating that the peptide disrupts virus binding to both primary and secondary interaction partners. Based on these findings, we propose that the antimicrobial effect of Pep19-2.5 is not limited to HSPG-dependent infections. Additionally, Pep19-2.5 may be a valuable tool for dissecting specific steps in the viral entry process.

Glycan-induced structural activation softens the human papillomavirus capsid for entry through reduction of intercapsomere flexibility

High-risk human papillomaviruses (HPVs) cause various cancers. While type-specific prophylactic vaccines are available, additional anti-viral strategies are highly desirable. Initial HPV cell entry involves receptor-switching induced by structural capsid modifications. These modifications are initiated by interactions with cellular heparan sulphates (HS), however, their molecular nature and functional consequences remain elusive. Combining virological assays with hydrogen/deuterium exchange mass spectrometry, and atomic force microscopy, we investigate the effect of capsid-HS binding and structural activation. We show how HS-induced structural activation requires a minimal HS-chain length and simultaneous engagement of several binding sites by a single HS molecule. This engagement introduces a pincer-like force that stabilizes the capsid in a conformation with extended capsomer linkers. It results in capsid enlargement and softening, thereby likely facilitating L1 proteolytic cleavage and subsequent L2-externalization, as needed for cell entry. Our data supports the further devising of prophylactic strategies against HPV infections.

WAVE1 and WAVE2 facilitate human papillomavirus-driven actin polymerization during cellular entry

Human PapillomavirusType 16 (HPV16) is an etiological agent of human cancers that requires endocytosis to initiate infection. HPV16 entry into epithelial cells occurs through a non-canonical endocytic pathway that is actin-driven, but it is not well understood how HPV16-cell surface interactions trigger actin reorganization in a way that facilitates entry. This study provides evidence that Wiskott-Aldrich syndrome protein family verprolin-homologous proteins 1 and 2 (WAVE1 and WAVE2) are molecular mediators of the actin polymerization that facilitates HPV endocytosis and intracellular trafficking. We demonstrate through post-transcriptional gene silencing and genome editing that WAVE1 and WAVE2 are critical for efficient HPV16 infection, and that restoration of each in knockout cells rescues HPV16 infection. Cells lacking WAVE1, WAVE2, or both, internalize HPV16 at a significantly reduced rate. Analysis of fluorescently labeled cells exposed to HPV16 and acquired by confocal fluorescence microscopy revealed that HPV16, WAVE1, WAVE2, and actin are all colocalized at the cellular dorsal surface. We also found that HPV16 stimulates WAVE1 and WAVE2-mediated cellular dorsal surface filopodia formation during the viral endocytic process. Taken together, this study provides evidence that the HPV endocytic process needed for infection is controlled by actin reorganization into filopodial protrusions and that this process is mediated by WAVE1 and WAVE2.

The effects of metabolites from three vaginal bacteria on the Syndecan-1 of cervical epithelial cells

This study aims to explore the impact of metabolites from three vaginal bacteria on the expression of Syndecan 1 (SDC-1). Human cervical epithelial cells (HcerEpic) were separately incubated with the cell-free supernatants of Lactobacillus crispatus (LCS group), Gardnerella vaginalis (GVS group), and Atopobium vaginalis (AVS group). LCS showed a proliferative effect on HcerEpic, with the most significant effect observed at a concentration of 30 % (P < 0.001). GVS and AVS exhibited some cytotoxicity, with significant growth inhibitory effects observed at concentrations of 30 % and 40 % (P < 0.01). Therefore, subsequent experiments were conducted using 30 % LCS, 40 % GVS, and 40 % AVS. In terms of cellular morphology, compared to the Control group, the LCS group showed more frequent fusion of cell sheets, with no obvious changes in the morphology of individual cells. In the GVS and AVS groups, some individual cells became round and smaller, with reduced protrusions and even a small amount of floating cells. The metabolic products of the three vaginal bacteria significantly upregulated the expression of IL-1β, IL-6, and TNF-α in HcerEpic (P < 0.05). In the GVS and AVS groups, the level of SDC-1 on the surface of HcerEpic was significantly decreased (P < 0.01), while the concentration of SDC-1 in the cell culture supernatant was significantly increased (P < 0.0001). Additionally, the level of SDC-1 mRNA was significantly downregulated (P < 0.01). In the LCS group, no significant changes were observed in SDC-1 protein and mRNA expression (P > 0.05). LCS promotes HcerEpic proliferation, without significant impact on SDC-1 expression and shedding. This provides molecular evidence for LCS as a protective factor against human papillomavirus infection in the cervix. Metabolites of GV and AV inhibit HcerEpic proliferation, induce cytokine secretion, suppress SDC-1 transcription and expression, and promote SDC-1 shedding.

Molecular mechanisms of human papilloma virus related skin cancers: A review

The human papillomavirus (HPV) belongs to the Papillomaviridae family of viruses which includes small, double-stranded DNA viral agents. Approximately 90% of HPV infections occur asymptomatically and resolve spontaneously. However, infection with high-risk viral strains can lead to the development of preneoplastic lesions, with an increased propensity to become cancerous. The location of these malignancies includes the oral cavity, cervix, vagina, anus, and vulva, among others. The role of HPV in carcinogenesis has already been demonstrated for the aforementioned neoplasia. However, regarding skin malignancies, the mechanisms that pinpoint the role played by HPV in their initiation and progression still elude our sight. Until now, the only fully understood mechanism of viral cutaneous oncogenesis is that of human herpes virus 8 infection in Kaposi sarcoma. In the case of HPV infection, however, most data focus on the role that beta strains exhibit in the oncogenesis of cutaneous squamous cell carcinoma (cSCC), along with ultraviolet radiation (UVR) and other environmental or genetic factors. However, recent epidemiological investigations have highlighted that HPV could also trigger the onset of other non-melanocytic, for example, basal cell carcinoma (BCC), and/or melanocytic skin cancers, for example, melanoma. Herein, we provide an overview of the role played by HPV in benign and malignant skin lesions with a particular focus on the main epidemiological, pathophysiological, and molecular aspects delineating the involvement of HPV in skin cancers.

Genetic predictors for bacterial vaginosis in women living with and at risk for HIV infection

PROBLEM

Bacterial vaginosis (BV) disproportionally impacts Black and Hispanic women, placing them at risk for HIV, sexually transmitted infections and preterm birth. It is unknown whether there are differences by genetic ancestry in BV risk or whether polymorphisms associated with BV risk differ by ancestry.

METHODS

Women's Interagency HIV Study (WIHS) participants with longitudinal Nugent scores were dichotomized as having (n = 319, Nugent 7-10) or not having BV (n = 367, Nugent 0-3). Genetic ancestry was defined by clustering of principal components from ancestry informative markers and further stratified by BV status. 627 single nucleotide polymorphisms (SNPs) across 41 genes important in mucosal defense were identified in the WIHS GWAS. A logistic regression analysis was adjusted for nongenetic predictors of BV and self-reported race/ethnicity to assess associations between genetic ancestry and genotype.

RESULTS

Self-reported race and genetic ancestry were associated with BV risk after adjustment for behavioral factors. Polymorphisms in mucosal defense genes including syndecans, cytokines and toll-like receptors (TLRs) were associated with BV in all ancestral groups.

CONCLUSIONS

The common association of syndecan, cytokine and TLR genes and the importance of immune function and inflammatory pathways in BV, suggests these should be targeted for further research on BV pathogenesis and therapeutics.

Therapeutic development targeting host heparan sulfate proteoglycan in SARS-CoV-2 infection

The global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to an urgent need for effective therapeutic options. SARS-CoV-2 is a novel coronavirus responsible for the COVID-19 pandemic that has resulted in significant morbidity and mortality worldwide. The virus is known to enter host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor, and emerging evidence suggests that heparan sulfate proteoglycans (HSPGs) play a crucial role in facilitating this process. HSPGs are abundant cell surface proteoglycan present in many tissues, including the lung, and have been shown to interact directly with the spike protein of SARS-CoV-2. This review aims to summarize the current understanding of the role of HSPGs in SARS-CoV-2 infection and the potential of developing new therapies targeting HSPGs.

Non-apoptotic cell death programs in cervical cancer with an emphasis on ferroptosis

BACKGROUND

Cervical cancer, a pernicious gynecological malignancy, causes the mortality of hundreds of thousands of females worldwide. Despite a considerable decline in mortality, the surging incidence rate among younger women has raised serious concerns. Immortality is the most important characteristic of tumor cells, hence the carcinogenesis of cervical cancer cells pivotally requires compromising with cell death mechanisms.

METHODS

The current study comprehensively reviewed the mechanisms of non-apoptotic cell death programs to provide possible disease management strategies.

RESULTS

Comprehensive evidence has stated that focusing on necroptosis, pyroptosis, and autophagy for disease management is associated with significant limitations such as insufficient understanding, contradictory functions, dependence on disease stage, and complexity of intracellular pathways. However, ferroptosis represents a predictable role in cervix carcinogenesis, and ferroptosis-related genes demonstrate a remarkable correlation with patient survival and clinical outcomes.

CONCLUSION

Ferroptosis may be an appropriate option for disease management strategies from predicting prognosis to treatment.

Myosin 9 and N-glycans jointly regulate human papillomavirus entry

Persistent high-risk HPV infection is closely associated with cervical cancer development, and there is no drug targeting HPV on the market at present, so it is particularly important to understand the interaction mechanism between HPV and the host which may provide the novel strategies for treating HPV diseases. HPV can hijack cell surface heparan sulfate proteoglycans (HSPGs) as primary receptors. However, the secondary entry receptors for HPV remain elusive. We identify myosin-9 (NMHC-IIA) as a host factor that interacts with HPV L1 protein and mediates HPV internalization. Efficient HPV entry required myosin-9 redistribution to the cell surface regulated by HPV-hijacked MEK-MLCK signaling. Myosin-9 maldistribution by ML-7 or ML-9 significantly inhibited HPV pseudoviruses infection in vitro and in vivo. Meanwhile, N-glycans, especially the galactose chains, may act as the decoy receptors for HPV, which can block the interaction of HPV to myosin-9 and influence the way of HPV infection. Taken together, we identify myosin-9 as a novel functional entry receptor for high-risk HPV both in vitro and in vivo, and unravel the new roles of myosin-9 and N-glycans in HPV entry, which provides the possibilities for host targets of antiviral drugs.

Small Molecule Inhibitors of Human Papillomavirus: A Review of Research from 1997 to 2021

Human papillomavirus (HPV) infections are the cause of warts, lesions and cancer, with different types of HPV causing different symptoms. HPV infections are the primary cause of cervical cancer. There are over 220 different types of HPV, and only nine of these can currently be vaccinated. There is a need to treat these viral infections without just treating the symptoms of the infection, as is currently the main method. There is a wide range of small molecules that have been used to inhibit various stages of the HPV infectious cycle. This review examined 132 small molecules from 121 studies that specifically target aspects of HPV infections. HPV DNA encodes for six early genes (E1 to E7, skipping E3) and two late genes (L1 and L2). According to the results, these targets for small molecule inhibitors fall into three categories: those targeting E1 and E2, targeting E6 and E7 and, finally, targeting L1 and L2. Inhibitors of E6 and E7 are the most widely studied targets, with the majority of HPV inhibition in this area. While compounds targeting both E1/E2 and E6/E7 have made it to clinical trials, there has been no significant advancement on the topic.

Targeting Cervical Cancer Stem Cells by Phytochemicals

Cervical cancer (CaCx) poses a significant global health challenge, ranking as the fourth most common cancer among women worldwide. Despite the emergence of advanced treatment strategies, recurrence remains a bottleneck in favorable treatment outcomes and contributes to poor prognosis. The chemo- or radio-therapy resistance coupled with frequent relapse of more aggressive tumors are some key components that contribute to CaCx-related mortality. The onset of therapy resistance and relapse are attributed to a small subset of, slow-proliferating Cancer Stem Cells (CSC). These CSCs possess the properties of tumorigenesis, self-renewal, and multi-lineage differentiation potential. Because of slow cycling, these cells maintain themselves in a semi-quiescent stage and protect themselves from different anti-proliferative anti-cancer drugs. Keeping in view recent advances in their phenotypic and functional characterization, the feasibility of targeting CSC and associated stem cell signaling bears a strong translational value. The presence of CSC has been reported in CaCx (CCSC) which remains a forefront area of research. However, we have yet to identify clinically useful leads that can target CCSC. There is compelling evidence that phytochemicals, because of their advantages over synthetic anticancer drugs, could emerge as potential therapeutic leads to target these CCSCs. The present article examined the potential of phytochemicals with reported anti-CSC properties and evaluated their future in preclinical and clinical applications against CaCx.

Research Progress on Antiviral Activity of Heparin

Heparin, as a glycosaminoglycan, is known for its anticoagulant and antithrombotic properties for several decades. Heparin is a life-saving drug and is widely used for anticoagulation in medical practice. In recent years, there have been extensive studies that heparin plays an important role in non-anticoagulant diseases, such as anti-inflammatory, anti-viral, anti-angiogenesis, anti-neoplastic, anti-metastatic effects, and so on. Clinical observation and in vitro experiments indicate that heparin displays a potential multitarget effect. In this brief review, we will summarize heparin and its derivative's recently studied progress for the treatment of various viral infections. The aim is to maximize the benefits of drugs through medically targeted development, to meet the unmet clinical needs of serious viral diseases.

Epigenetic and Genetic Keys to Fight HPV-Related Cancers

Cervical cancer ranks as the fourth most prevalent cancer among women globally, with approximately 600,000 new cases being diagnosed each year. The principal driver of cervical cancer is the human papillomavirus (HPV), where viral oncoproteins E6 and E7 undertake the role of driving its carcinogenic potential. Despite extensive investigative efforts, numerous facets concerning HPV infection, replication, and pathogenesis remain shrouded in uncertainty. The virus operates through a variety of epigenetic mechanisms, and the epigenetic signature of HPV-related tumors is a major bottleneck in our understanding of the disease. Recent investigations have unveiled the capacity of viral oncoproteins to influence epigenetic changes within HPV-related tumors, and conversely, these tumors exert an influence on the surrounding epigenetic landscape. Given the escalating occurrence of HPV-triggered tumors and the deficiency of efficacious treatments, substantial challenges emerge. A promising avenue to address this challenge lies in epigenetic modulators. This review aggregates and dissects potential epigenetic modulators capable of combatting HPV-associated infections and diseases. By delving into these modulators, novel avenues for therapeutic interventions against HPV-linked cancers have come to the fore.

Epidemiology, Molecular Pathogenesis, Immuno-Pathogenesis, Immune Escape Mechanisms and Vaccine Evaluation for HPV-Associated Carcinogenesis

Human papillomavirus (HPV) is implicated in over 90% of cervical cancer cases, with factors like regional variability, HPV genotype, the population studied, HPV vaccination status, and anatomical sample collection location influencing the prevalence and pathology of HPV-induced cancer. HPV-16 and -18 are mainly responsible for the progression of several cancers, including cervix, anus, vagina, penis, vulva, and oropharynx. The oncogenic ability of HPV is not only sufficient for the progression of malignancy, but also for other tumor-generating steps required for the production of invasive cancer, such as coinfection with other viruses, lifestyle factors such as high parity, smoking, tobacco chewing, use of contraceptives for a long time, and immune responses such as stimulation of chronic stromal inflammation and immune deviation in the tumor microenvironment. Viral evasion from immunosurveillance also supports viral persistence, and virus-like particle-based prophylactic vaccines have been licensed, which are effective against high-risk HPV types. In addition, vaccination awareness programs and preventive strategies could help reduce the rate and incidence of HPV infection. In this review, we emphasize HPV infection and its role in cancer progression, molecular and immunopathogenesis, host immune response, immune evasion by HPV, vaccination, and preventive schemes battling HPV infection and HPV-related cancers.

Variations in Genes Encoding Human Papillomavirus Binding Receptors and Susceptibility to Cervical Precancer

BACKGROUND

Cervical cancer oncogenesis starts with human papillomavirus (HPV) cell entry after binding to host cell surface receptors; however, the mechanism is not fully known. We examined polymorphisms in receptor genes hypothesized to be necessary for HPV cell entry and assessed their associations with clinical progression to precancer.

METHODS

African American women (N = 1,728) from the MACS/WIHS Combined Cohort Study were included. Two case-control study designs were used-cases with histology-based precancer (CIN3+) and controls without; and cases with cytology-based precancer [high-grade squamous intraepithelial lesions (HSIL)] and controls without. SNPs in candidate genes (SDC1, SDC2, SDC3, SDC4, GPC1, GPC2, GPC3, GPC4, GPC5, GPC6, and ITGA6) were genotyped using an Illumina Omni2.5-quad beadchip. Logistic regression was used to assess the associations in all participants and by HPV genotypes, after adjusting for age, human immunodeficiency virus serostatus, CD4 T cells, and three principal components for ancestry.

RESULTS

Minor alleles in SNPs rs77122854 (SDC3), rs73971695, rs79336862 (ITGA6), rs57528020, rs201337456, rs11987725 (SDC2), rs115880588, rs115738853, and rs9301825 (GPC5) were associated with increased odds of both CIN3+ and HSIL, whereas, rs35927186 (GPC5) was found to decrease the odds for both outcomes (P value ≤ 0.01). Among those infected with Alpha-9 HPV types, rs722377 (SDC3), rs16860468, rs2356798 (ITGA6), rs11987725 (SDC2), and rs3848051 (GPC5) were associated with increased odds of both precancer outcomes.

CONCLUSIONS

Polymorphisms in genes that encode binding receptors for HPV cell entry may play a role in cervical precancer progression.

IMPACT

Our findings are hypothesis generating and support further exploration of mechanisms of HPV entry genes that may help prevent progression to cervical precancer.

Viral protein nanoparticles (Part 1): Pharmaceutical characteristics

Viral protein nanoparticles fill the gap between viruses and synthetic nanoparticles. Combining advantageous properties of both systems, they have revolutionized pharmaceutical research. Virus-like particles are characterized by a structure identical to viruses but lacking genetic material. Another type of viral protein nanoparticles, virosomes, are similar to liposomes but include viral spike proteins. Both systems are effective and safe vaccine candidates capable of overcoming the disadvantages of both traditional and subunit vaccines. Besides, their particulate structure, biocompatibility, and biodegradability make them good candidates as vectors for drug and gene delivery, and for diagnostic applications. In this review, we analyze viral protein nanoparticles from a pharmaceutical perspective and examine current research focused on their development process, from production to administration. Advances in synthesis, modification and formulation of viral protein nanoparticles are critical so that large-scale production of viral protein nanoparticle products becomes viable and affordable, which ultimately will increase their market penetration in the future. We will discuss their expression systems, modification strategies, formulation, biopharmaceutical properties, and biocompatibility.

Immune checkpoint inhibition combined with targeted therapy using a novel virus-like drug conjugate induces complete responses in a murine model of local and distant tumors

Metastases remain the leading cause of cancer-related death worldwide. Therefore, improving the treatment efficacy against such tumors is essential to enhance patient survival. AU-011 (belzupacap sarotalocan) is a new virus-like drug conjugate which is currently in clinical development for the treatment of small choroidal melanoma and high-risk indeterminate lesions in the eye. Upon light activation, AU-011 induces rapid necrotic cell death which is pro-inflammatory and pro-immunogenic, resulting in an anti-tumor immune response. As AU-011 is known to induce systemic anti-tumor immune responses, we investigated whether this combination therapy would also be effective against distant, untreated tumors, as a model for treating local and distant tumors by abscopal immune effects. We compared the efficacy of combining AU-011 with several different checkpoint blockade antibodies to identify optimal treatment regimens in an in vivo tumor model. We show that AU-011 induces immunogenic cell death through the release and exposure of damage-associated molecular patterns (DAMPs), resulting in the maturation of dendritic cells in vitro. Furthermore, we show that AU-011 accumulates in MC38 tumors over time and that ICI enhances the efficacy of AU-011 against established tumors in mice, resulting in complete responses for specific combinations in all treated animals bearing a single MC38 tumor. Finally, we show that AU-011 and anti-PD-L1/anti-LAG-3 antibody treatment was an optimal combination in an abscopal model, inducing complete responses in approximately 75% of animals. Our data show the feasibility of combining AU-011 with PD-L1 and LAG-3 antibodies for the treatment of primary and distant tumors.

Folliculin Prevents Lysosomal Degradation of Human Papillomavirus To Support Infectious Cell Entry

Human papillomavirus (HPV) infects epithelial basal cells in the mucosa and either proliferates with the differentiation of the basal cells or persists in them. Multiple host factors are required to support the HPV life cycle; however, the molecular mechanisms involved in cell entry are not yet fully understood. In this study, we performed a genome-wide clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated protein 9 (Cas9) knockout (KO) screen in HeLa cells and identified folliculin (FLCN), a GTPase-activating protein for Rag GTPases, as an important host factor for HPV infection. The introduction of single guide RNAs for the FLCN gene into HeLa, HaCaT, and ectocervical Ect1 cells reduced infection by HPV18 pseudovirions (18PsVs) and 16PsVs. FLCN KO HeLa cells also exhibited strong resistance to infection with 18PsVs and 16PsVs; nevertheless, they remained highly susceptible to infections with vesicular stomatitis virus glycoprotein-pseudotyped lentivirus and adeno-associated virus. Immunofluorescence microscopy revealed that the numbers of virions binding to the cell surface were slightly increased in FLCN KO cells. However, virion internalization analysis showed that the internalized virions were rapidly degraded in FLCN KO cells. This degradation was blocked by treatment with the lysosome inhibitor bafilomycin A1. Furthermore, the virion degradation phenotype was also observed in Ras-related GTP-binding protein C (RagC) KO cells. These results suggest that FLCN prevents the lysosomal degradation of incoming HPV virions by enhancing lysosomal RagC activity. IMPORTANCE Cell entry by human papillomavirus (HPV) involves a cellular retrograde transport pathway from the endosome to the trans-Golgi network/Golgi apparatus. However, the mechanism by which this viral trafficking is safeguarded is poorly understood. This is the first study showing that the GTPase-activating protein folliculin (FLCN) protects incoming HPV virions from lysosomal degradation and supports infectious cell entry by activating the Rag GTPases, presumably through the suppression of excessive lysosomal biosynthesis. These findings provide new insights into the effects of small GTPase activity regulation on HPV cell entry and enhance our understanding of the HPV degradation pathway.

Critical Residues Involved in the Coassembly of L1 and L2 Capsid Proteins of Human Papillomavirus 16

Human papillomaviruses (HPV) are small DNA viruses associated with cervical cancer, warts, and other epithelial tumors. Structural studies have shown that the HPV capsid consists of 360 copies of the major capsid protein, L1, arranged as 72 pentamers in a T=7 icosahedral lattice, coassembling with substoichiometric amounts of the minor capsid protein, L2. However, the residues involved in the coassembly of L1 and L2 remain undefined due to the lack of structure information. Here, we investigated the solvent accessibility surfaces (SASs) of the central cavity residues of the HPV16 L1 pentamer in the crystal structure because those internal exposed residues might mediate the association with L2. Twenty residues in L1 protein were selected to be analyzed, with four residues in the lumen of the L1 pentamer identified as important: F256, R315, Q317, and T340. Mutations to these four residues reduced the PsV (pseudovirus) infection capacity in 293FT cells, and mutations to R315, Q317, and T340 substantially perturb L2 from coassembling into L1 capsid. Compared with wild-type (WT) PsVs, these mutant PsVs also have a reduced ability to become internalized into host cells. Finally, we identified a stretch of negatively charged residues on L2 (amino acids [aa] 337 to 340 [EEIE]), mutations to which completely abrogate L2 assembly into L1 capsid and subsequently impair the endocytosis and infectivity of HPV16 PsVs. These findings shed light on the elusive coassembly between HPV L1 and L2. IMPORTANCE Over 200 types of HPV have been isolated, with several high-risk types correlated with the occurrence of cervical cancer. The HPV major capsid protein, L1, assembles into a T=7 icosahedral viral shell, and associates with the minor capsid protein, L2, which plays a critical role in the HPV life cycle. Despite the important role of the L2 protein, its structure and coassembly with L1 remain elusive. In this study, we analyzed the amino acid residues at the proposed interface between L1 and L2. Certain mutations at these sites decreased the amount of L2 protein assembled into the capsid, which, in turn, led to a decrease in viral infectivity. Knowledge about these residues and the coassembly of L1 and L2 could help to expand our understanding of HPV biology and aid in the development of countermeasures against a wide range of HPV types by targeting the L2 protein.

Current Challenges and Opportunities of Photodynamic Therapy against Cancer

BACKGROUND

Photodynamic therapy (PDT) is an established, minimally invasive treatment for specific types of cancer. During PDT, reactive oxygen species (ROS) are generated that ultimately induce cell death and disruption of the tumor area. Moreover, PDT can result in damage to the tumor vasculature and induce the release and/or exposure of damage-associated molecular patterns (DAMPs) that may initiate an antitumor immune response. However, there are currently several challenges of PDT that limit its widespread application for certain indications in the clinic.

METHODS

A literature study was conducted to comprehensively discuss these challenges and to identify opportunities for improvement.

RESULTS

The most notable challenges of PDT and opportunities to improve them have been identified and discussed.

CONCLUSIONS

The recent efforts to improve the current challenges of PDT are promising, most notably those that focus on enhancing immune responses initiated by the treatment. The application of these improvements has the potential to enhance the antitumor efficacy of PDT, thereby broadening its potential application in the clinic.

Tetraspanin-enriched Microdomain Containing CD151, CD9, and TSPAN 8 - Potential Mediators of Entry and Exit Mechanisms in Respiratory Viruses Including SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in Wuhan, the Hubei region of China, has become a pandemic worldwide. It can transmit through droplets and enter via oral, nasal, and eye mucous membranes. It consists of single-stranded RNA (positive-sense), nonstructural proteins including enzymes and transcriptional proteins, and structural proteins such as Spike, Membrane, Envelope, and Nucleocapsid -proteins. SARS-CoV-2 mediates S-proteins entry and exit via binding to host cell surface proteins like tetraspanins. The transmembrane tetraspanins, CD151, CD9, and tetraspanin 8 (TSPAN8), facilitate the entry of novel coronaviruses by scaffolding host cell receptors and proteases. Also, CD151 was reported to increase airway hyperresponsiveness to calcium and nuclear viral export signaling. They may facilitate entry and exit by activating the serine proteases required to prime S-proteins in tetraspanin-enriched microdomains (TEMs). This article updates recent advances in structural proteins, their epitopes and putative receptors, and their regulation by proteases associated with TEMs. This review furnishes recent updates on the role of CD151 in the pathophysiology of SARS-CoV-2. We describe the role of CD151 in a possible mechanism of entry and exit in the airway, a major site for infection of SARS-CoV-2. We also updated current knowledge on the role of CD9 and TSPAN 8 in the entry and exit mechanism of coronaviruses. Finally, we discussed the importance of some small molecules which target CD151 as possible targeted therapeutics for COVID-19. In conclusion, this study could identify new targets and specific therapeutics to control emerging virus infections.

Scramblases as Regulators of Proteolytic ADAM Function

Proteolytic ectodomain release is a key mechanism for regulating the function of many cell surface proteins. The sheddases ADAM10 and ADAM17 are the best-characterized members of the family of transmembrane disintegrin-like metalloproteinase. Constitutive proteolytic activities are low but can be abruptly upregulated via inside-out signaling triggered by diverse activating events. Emerging evidence indicates that the plasma membrane itself must be assigned a dominant role in upregulation of sheddase function. Data are discussed that tentatively identify phospholipid scramblases as central players during these events. We propose that scramblase-dependent externalization of the negatively charged phospholipid phosphatidylserine (PS) plays an important role in the final activation step of ADAM10 and ADAM17. In this manuscript, we summarize the current knowledge on the interplay of cell membrane changes, PS exposure, and proteolytic activity of transmembrane proteases as well as the potential consequences in the context of immune response, infection, and cancer. The novel concept that scramblases regulate the action of ADAM-proteases may be extendable to other functional proteins that act at the cell surface.

The association of telomere maintenance and TERT expression with susceptibility to human papillomavirus infection in cervical epithelium

The role of telomerase reverse transcriptase (TERT) induction and telomere maintenance in carcinogenesis including cervical cancer (CC) pathogenesis has been well established. However, it remains unclear whether they affect infection of high-risk human papillomavirus (hrHPV), an initiating event for CC development. Similarly, genetic variants at the TERT locus are shown to be associated with susceptibility to CC, but it is unclear whether these SNPs modify the risk for cervical HPV infection. Here we show that in CC-derived HeLa cells, TERT overexpression inhibits, while its depletion upregulates expression of Syndecan-1 (SDC-1), a key component for HPV entry receptors. The TCGA cohort of CC analyses reveals an inverse correlation between TERT and SDC-1 expression (R = -0.23, P = 0.001). We further recruited 1330 females (520 non-HPV and 810 hrHPV-infected) without CC or high-grade cervical intraepithelial neoplasia to analyze telomeres in cervical epithelial cells and SNPs at rs2736098, rs2736100 and rs2736108, previously identified TERT SNPs for CC risk. Non-infected females exhibited age-related telomere shortening in cervical epithelial cells and their telomeres were significantly longer than those in hrHPV-infected group (1.31 ± 0.62 vs 1.19 ± 0.48, P < 0.001). There were no differences in rs2736098 and rs2736100 genotypes, but non-infected individuals had significantly a higher C-allele frequency (associated with higher TERT expression) while lower T-allele levels at rs2736108 compared with those in the hrHPV group (P = 0.020). Collectively, appropriate telomere maintenance and TERT expression in normal cervical cells may prevent CC by modulating hrHPV infection predisposition, although they are required for CC development and progression.

Protamine Sulfate Is a Potent Inhibitor of Human Papillomavirus Infection In Vitro and In Vivo

Human papillomavirus (HPV) infections are transmitted through sexual or other close contact and are etiologically associated with epithelial warts, papillomas, and intraepithelial lesions that may progress to cancer. Indeed, 4.8% of the global cancer burden is linked to HPV infection. Highly effective vaccines protect against two to nine of the most medically important HPV genotypes, yet vaccine uptake is inadequate and/or cost prohibitive in many settings. With HPV-related cancer incidence expected to rise over the coming decades, there is a need for effective HPV microbicides. Herein, we demonstrate the strong inhibitory activity of the heparin-neutralizing drug protamine sulfate (PS) against HPV infection. Pretreatment of cells with PS greatly reduced infection, regardless of HPV genotype or virus source. Vaginal application of PS prevented infection of the murine genital tract by HPV pseudovirions. Time-of-addition assays where PS was added to cells before infection, during infection, or after viral attachment demonstrated strong inhibitory activities on early infection steps. No effect on virus infection was found for cell lines deficient in heparan sulfate expression, suggesting that PS binds to heparan sulfate on the cell surface. Consistent with this, prophylactic PS exposure prevented viral attachment, including under low-pH conditions akin to the human vaginal tract. Our findings suggest PS acts dually to prevent HPV infection: prophylactic treatment prevents HPV attachment to host cells, and postattachment administration alters viral entry. Clinical trials are warranted to determine whether protamine-based products are effective as topical microbicides against genital HPVs.

A review on the role of epidermal growth factor signaling in the development, progression and treatment of cervical cancer

The sub-committee constituted by the Indian Council of Medical Research (ICMR) for the management of cervical cancer (CC) detailed in the consensus document (2016) reported CC as a significant cause of morbidity and mortality in women. The incidence of an increase in CC and associated mortality in women is a major cause of cancer. To date, human papilloma viral (HPV) infection accounts for more than 99% of CC. However, there are individuals infected with HPV do not develop CC. There is a greater correlation between HPV infection and upregulation of the epidermal growth factor receptor (EGFR) signaling cascade during the initiation, sustenance, and progression of CC. Therefore, EGFR is often targeted to treat CC using tyrosine kinase inhibitors (TKIs) and monoclonal antibodies (mAB). The current review analyzed the existing clinical/pre-clinical studies and the significance of EGFR abundance using the Kaplan-Meier (KM) survival plot analysis for disease-free survival (DFS) and overall survival (OS). We performed a series of bioinformatics analyses to screen the crucial role of the EGFR gene in CC. Further, different transcription factors that are dysregulated due to EGFR abundance and their relevance were determined using computational tools in this review. Endogenous microRNAs (miRNA) that undergo changes due to alterations in EGFR during CC were identified using computational database and consolidated the information obtained with the published in the area of miRNA and EGFR with special reference to the initiation, sustenance and progression of CC. The current review aims to consolidate contemporary approaches for targeting CC using EGFR and highlight the current role of miRNA and genes that are differently regulated during CC involving EGFR mutations. Potential resistance to the available EGFR therapies such as TKIs and mABs and the need for better therapies are also extensively reviewed for the development of newer therapeutic molecules with better efficacy.

FGF signalling facilitates cervical cancer progression

Cervical cancer is one of the most frequently diagnosed cancers in women worldwide. While cervical cancer is caused by human papillomavirus (HPV), not all females infected with HPV develop the disease, suggesting that other factors might facilitate its progression. Growing evidence supports the involvement of the fibroblast growth factor receptor (FGFR) axis in several cancers, including gynecological. However, for cervical cancer, the molecular mechanisms that underpin the disease remain poorly understood, including the role of FGFR signaling. The aim of this study was to investigate FGF(R) signaling in cervical cancer through bioinformatic analysis of cell line and patient data and through detailed expression profiling, manipulation of the FGFR axis, and downstream phenotypic analysis in cell lines (HeLa, SiHa, and CaSki). Expression (protein and mRNA) analysis demonstrated that FGFR1b/c, FGFR2b/c, FGFR4, FGF2, FGF4, and FGF7 were expressed in all three lines. Interestingly, FGFR1 and 2 localized to the nucleus, supporting that nuclear FGFRs could act as transcription factors. Importantly, 2D and 3D cell cultures demonstrated that FGFR activation can facilitate cell functions correlated with invasive disease. Collectively, this study supports an association between FGFR signaling and cervical cancer progression, laying the foundations for the development of therapeutic approaches targeting FGFR in this disease.

HPV16 Entry into Epithelial Cells: Running a Gauntlet

During initial infection, human papillomaviruses (HPV) take an unusual trafficking pathway through their host cell. It begins with a long period on the cell surface, during which the capsid is primed and a virus entry platform is formed. A specific type of clathrin-independent endocytosis and subsequent retrograde trafficking to the trans-Golgi network follow this. Cellular reorganization processes, which take place during mitosis, enable further virus transport and the establishment of infection while evading intrinsic cellular immune defenses. First, the fragmentation of the Golgi allows the release of membrane-encased virions, which are partially protected from cytoplasmic restriction factors. Second, the nuclear envelope breakdown opens the gate for these virus–vesicles to the cell nucleus. Third, the dis- and re-assembly of the PML nuclear bodies leads to the formation of modified virus-associated PML subnuclear structures, enabling viral transcription and replication. While remnants of the major capsid protein L1 and the viral DNA remain in a transport vesicle, the viral capsid protein L2 plays a crucial role during virus entry, as it adopts a membrane-spanning conformation for interaction with various cellular proteins to establish a successful infection. In this review, we follow the oncogenic HPV type 16 during its long journey into the nucleus, and contrast pro- and antiviral processes.

Glucocorticoids Elevate Pseudomonas aeruginosa Binding to Airway Epithelium by Upregulating Syndecan-1 Expression

Glucocorticoids are commonly used for the treatment of asthma and chronic obstructive pulmonary disease (COPD). Inhaled corticosteroids are associated with a significantly increased risk of pneumonia. Syndecan-1 (SDC1) located in the cell membrane of airway epithelial cell is the crucial molecule mediating infections by P. aeruginosa (PA). In the present study, we found that SDC1 expression was upregulated and the adhesion of PA to human bronchial epithelial (HBE) cells increased to 125 and 138%, respectively, after stimulation by dexamethasone or budesonide. The HBE cells knocking down SDC1 showed lower affinity to PA compared with control. CCAAT-enhancer-binding protein β (C/EBP β) and its phosphorylated form participated in the regulation of glucocorticoid to SDC1 for interfering C/EBP β or inhibiting phosphorylation of C/EBP β by LiCl and BIO, which are inhibitors of glycogen synthase kinase 3β (GSK-3β), and could prevent glucocorticoids from upregulating SDC1 expression. One should be cautious in administering glucocorticoids in chronic lung disease because of their property of increasing the expression of SDC1 and PA binding to the airway epithelium.

Tetraspanins: Host Factors in Viral Infections

Tetraspanins are transmembrane glycoproteins that have been shown increasing interest as host factors in infectious diseases. In particular, they were implicated in the pathogenesis of both non-enveloped (human papillomavirus (HPV)) and enveloped (human immunodeficiency virus (HIV), Zika, influenza A virus, (IAV), and coronavirus) viruses through multiple stages of infection, from the initial cell membrane attachment to the syncytium formation and viral particle release. However, the mechanisms by which different tetraspanins mediate their effects vary. This review aimed to compare and contrast the role of tetraspanins in the life cycles of HPV, HIV, Zika, IAV, and coronavirus viruses, which cause the most significant health and economic burdens to society. In doing so, a better understanding of the relative contribution of tetraspanins in virus infection will allow for a more targeted approach in the treatment of these diseases.

Recent Advances in Our Understanding of the Infectious Entry Pathway of Human Papillomavirus Type 16

Papillomaviruses are a diverse viral species, but several types such as HPV16 are given special attention due to their contribution towards the pathogenesis of several major cancers. In this review, we will summarize how the knowledge of HPV16 entry has expanded since the last comprehensive HPV16 entry review our lab published in 2017.

The long and winding road: human papillomavirus entry and subcellular trafficking

Human papillomaviruses (HPVs) infect and replicate in differentiating mucosal and cutaneous epithelium. Most HPV infections are asymptomatic or cause transient benign neoplasia. However, persistent infections by oncogenic HPV types can progress to cancer. During infectious entry into host keratinocytes, HPV particles interact with many host proteins, beginning with major capsid protein L1 binding to cellular heparan sulfate and a series of enzymatic capsid modifications that promote infectious cellular entry. After utilizing the endosomal pathway to uncoat the viral genome (vDNA), the minor capsid protein L2/vDNA complex is retrograde trafficked to the Golgi, and thereafter, to the nucleus where viral transcription initiates. Post-Golgi trafficking is dependent on mitosis, with L2-dependent tethering of vDNA to mitotic chromosomes before accumulation at nuclear substructures in G1. This review summarizes the current knowledge of the HPV entry pathway, the role of cellular proteins in this process, and notes many gaps in our understanding.

Lipid metabolism and oxidative stress in HPV-related cancers

High-risk human papillomavirus (HR-HPVs) are associated with the development of cervical, anus, vagina, vulva, penis, and oropharynx cancer. HR-HPVs target and modify the function of different cell biomolecules such as glucose, amino acids, lipids, among others. The latter induce cell proliferation, cell death evasion, and genomic instability resulting in cell transformation. Moreover, lipids are essential biomolecules in HR-HPVs infection and cell vesicular trafficking. They are also critical in producing cellular energy, the epithelial-mesenchymal transition (EMT) process, and therapy resistance of HPV-related cancers. HPV proteins induce oxidative stress (OS), which in turn promotes lipid peroxidation and cell damage, resulting in cell death such as apoptosis, autophagy, and ferroptosis. HR-HPV-related cancer cells cope with OS and lipid peroxidation, preventing cell death; however, these cells are sensitized by OS, which could be used as a target for redox therapies to induce their elimination. This review focuses on the role of lipids in HR-HPV infection and HPV-related cancer development, maintenance, resistance to therapy, and the possible treatments associated with lipids. Furthermore, we emphasize the significant role of OS in lipid peroxidation to induce cell death through apoptosis, autophagy, and ferroptosis to eliminate HPV-related cancers.

Inherited and acquired corona of coronavirus in the host: Inspiration from the biomolecular corona of nanoparticles

The family of coronavirus are named for their crown shape. Encoded by the genetic material inherited from the coronavirus itself, this intrinsic well-known "viral corona" is considered an "inherited corona". After contact with mucosa or the entrance into the host, bare coronaviruses can become covered by a group of dissolved biomolecules to form one or multiple layers of biomolecules. The layers acquired from the surrounding environment are named the "acquired corona". We highlight here the possible role of the acquired corona in the pathogenesis of coronaviruses, which will generate fresh insight into the nature of various coronavirus-host interactions.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

Heparanase-enhanced Shedding of Syndecan-1 and Its Role in Driving Disease Pathogenesis and Progression

Both heparanase and syndecan-1 are known to be present and active in disease pathobiology. An important feature of syndecan-1 related to its role in pathologies is that it can be shed from the surface of cells as an intact ectodomain composed of the extracellular core protein and attached heparan sulfate and chondroitin sulfate chains. Shed syndecan-1 remains functional and impacts cell behavior both locally and distally from its cell of origin. Shedding of syndecan-1 is initiated by a variety of stimuli and accomplished predominantly by the action of matrix metalloproteinases. The accessibility of these proteases to the core protein of syndecan-1 is enhanced, and shedding facilitated, when the heparan sulfate chains of syndecan-1 have been shortened by the enzymatic activity of heparanase. Interestingly, heparanase also enhances shedding by upregulating the expression of matrix metalloproteinases. Recent studies have revealed that heparanase-induced syndecan-1 shedding contributes to the pathogenesis and progression of cancer and viral infection, as well as other septic and non-septic inflammatory states. This review discusses the heparanase/shed syndecan-1 axis in disease pathogenesis and progression, the potential of targeting this axis therapeutically, and the possibility that this axis is widespread and of influence in many diseases.

Autophagy is induced in human keratinocytes during human papillomavirus 11 pseudovirion entry

Human papillomavirus type 11 (HPV11) is one of the main causes of condyloma acuminatum, a widespread sexually transmitted disease. During infection of its primary target cell, keratinocytes, it is likely to encounter the autophagy pathway, which is an intracellular maintenance process that is also able to target invading pathogens. It is currently unknown whether HPV11 is targeted by autophagy or whether it is able to escape autophagy-mediated killing. Here, we investigated the autophagy response during HPV11 pseudovirion (PsV) entry in human keratinocytes. Transmission electron microscopy showed that intracellular PsVs were sequestered in lumen of double-membrane autophagosomes that subsequently appeared to fuse with lysosomes, while confocal microscopy showed induction LC3 puncta, the hallmark of induced autophagy activity. Furthermore, quantitative infection assays showed that high autophagy activity resulted in reduced HPV11 PsV infectivity. Therefore, the autophagy pathway seemed to actively target invading HPV11 PsVs for destruction in the autolysosome. Western analysis on the phosphorylation state of autophagy regulators and upstream pathways indicated that autophagy was activated through interplay between Erk and Akt signaling. In conclusion, autophagy functions as a cellular protection mechanism against intracellular HPV11 and therefore therapies that stimulate autophagy may prevent recurrent condyloma acuminatum by helping eliminate latent HPV11 infections.

Theta-Defensins Inhibit High-Risk Human Papillomavirus Infection Through Charge-Driven Capsid Clustering

Persistent infection with high-risk human papillomavirus (hrHPV) genotypes results in a large number of anogenital and head and neck cancers worldwide. Although prophylactic vaccination coverage has improved, there remains a need to develop methods that inhibit viral transmission toward preventing the spread of HPV-driven disease. Defensins are a class of innate immune effector peptides that function to protect hosts from infection by pathogens such as viruses and bacteria. Previous work utilizing α and β defensins from humans has demonstrated that the α-defensin HD5 is effective at inhibiting the most common high-risk genotype, HPV16. A third class of defensin that has yet to be explored are θ-defensins: small, 18-amino acid cyclic peptides found in old-world monkeys whose unique structure makes them both highly cationic and resistant to degradation. Here we show that the prototype θ-defensin, rhesus theta defensin 1, inhibits hrHPV infection through a mechanism involving capsid clustering that inhibits virions from binding to cell surface receptor complexes.

Vesicular trafficking permits evasion of cGAS/STING surveillance during initial human papillomavirus infection

Oncogenic human papillomaviruses (HPVs) replicate in differentiating epithelium, causing 5% of cancers worldwide. Like most other DNA viruses, HPV infection initiates after trafficking viral genome (vDNA) to host cell nuclei. Cells possess innate surveillance pathways to detect microbial components or physiological stresses often associated with microbial infections. One of these pathways, cGAS/STING, induces IRF3-dependent antiviral interferon (IFN) responses upon detection of cytosolic DNA. Virion-associated vDNA can activate cGAS/STING during initial viral entry and uncoating/trafficking, and thus cGAS/STING is an obstacle to many DNA viruses. HPV has a unique vesicular trafficking pathway compared to many other DNA viruses. As the capsid uncoats within acidic endosomal compartments, minor capsid protein L2 protrudes across vesicular membranes to facilitate transport of vDNA to the Golgi. L2/vDNA resides within the Golgi lumen until G2/M, whereupon vesicular L2/vDNA traffics along spindle microtubules, tethering to chromosomes to access daughter cell nuclei. L2/vDNA-containing vesicles likely remain intact until G1, following nuclear envelope reformation. We hypothesize that this unique vesicular trafficking protects HPV from cGAS/STING surveillance. Here, we investigate cGAS/STING responses to HPV infection. DNA transfection resulted in acute cGAS/STING activation and downstream IFN responses. In contrast, HPV infection elicited minimal cGAS/STING and IFN responses. To determine the role of vesicular trafficking in cGAS/STING evasion, we forced premature viral penetration of vesicular membranes with membrane-perturbing cationic lipids. Such treatment renders a non-infectious trafficking-defective mutant HPV infectious, yet susceptible to cGAS/STING detection. Overall, HPV evades cGAS/STING by its unique subcellular trafficking, a property that may contribute to establishment of infection.

New insights in Hippo signalling alteration in human papillomavirus-related cancers

The persistent infection with high-risk human papillomavirus (HPV) is an etiologic factor for the development of different types of cancers, mainly attributed to the continuous expression of E6 and E7 HPV oncoproteins, which regulate several cell signalling pathways including the Hippo pathway. It has been demonstrated that E6 proteins promote the increase of the Hippo elements YAP, TAZ and TEAD, at protein level, as well as their transcriptional targets. Also, E6 and E7 oncoproteins promote nuclear YAP localization and a decrease in YAP negative regulators such as MST1, PTPN14 or SOCS6. Interestingly, Hippo signalling components modulate HPV activity, such as TEAD1 and the transcriptional co-factor VGLL1, induce the activation of HPV early and late promoters, while hyperactivation of YAP in specific cells facilitates virus infection by increasing putative HPV receptors and by evading innate immunity. Additionally, alterations in Hippo signalling elements have been found in HPV-related cancers and particularly, the involvement of HPV oncoproteins on the regulation of some of these Hippo components has been also proposed, although the precise mechanisms remain unclear. The present review addresses the recent findings describing the interplay between HPV and Hippo signalling in HPV-related cancers, a fact that highlights the importance of developing more in-depth studies in this field to establish key therapeutic targets.

p120 catenin recruits HPV to γ-secretase to promote virus infection

During internalization and trafficking, human papillomavirus (HPV) moves from the cell surface to the endosome where the transmembrane protease γ-secretase promotes insertion of the viral L2 capsid protein into the endosome membrane. Protrusion of L2 through the endosome membrane into the cytosol allows the recruitment of cytosolic host factors that target the virus to the Golgi en route for productive infection. How endosome-localized HPV is delivered to γ-secretase, a decisive infection step, is unclear. Here we demonstrate that cytosolic p120 catenin, likely via an unidentified transmembrane protein, interacts with HPV at early time-points during viral internalization and trafficking. In the endosome, p120 is not required for low pH-dependent disassembly of the HPV L1 capsid protein from the incoming virion. Rather, p120 is required for HPV to interact with γ-secretase-an interaction that ensures the virus is transported along a productive route. Our findings clarify an enigmatic HPV infection step and provide critical insights into HPV infection that may lead to new therapeutic strategies against HPV-induced diseases.

Regulation of autophagy by high- and low-risk human papillomaviruses

While high-risk human papillomavirus (HR-HPV) infection is related to the development of cervical, vulvar, anal, penile and oropharyngeal cancer, low-risk human papillomavirus (LR-HPV) infection is implicated in about 90% of genital warts, which rarely progress to cancer. The carcinogenic role of HR-HPV is due to the overexpression of HPV E5, E6 and E7 oncoproteins which target and modify cellular proteins implicated in cell proliferation, apoptosis and immortalization. LR-HPV proteins also target and modify some of these processes; however, their oncogenic potential is lower than that of HR-HPV. HR-HPVs have substantial differences with LR-HPVs such as viral integration into the cell genome, induction of p53 and retinoblastoma protein degradation, alternative splicing in HR-HPV E6-E7 open reading frames, among others. In addition, LR-HPV can activate the autophagy process in infected cells while HR-HPV infection deactivates it. However, in cancer HR-HPV might reactivate autophagy in advance stages. Autophagy is a catabolic process that maintains cell homoeostasis by lysosomal degradation and recycling of damaged macromolecules and organelles; nevertheless, depending upon cellular context autophagy may also induce cell death. Therefore, autophagy can contribute either as a promotor or as a suppressor of tumours. In this review, we focus on the role of HR-HPV and LR-HPV in autophagy during viral infection and cancer development. Additionally, we review key regulatory molecules such as microRNAs in HPV present during autophagy, and we emphasize the potential use of cancer treatments associated with autophagy in HPV-related cancers.

Manipulation of JAK/STAT Signalling by High-Risk HPVs: Potential Therapeutic Targets for HPV-Associated Malignancies

Human papillomaviruses (HPVs) are small, DNA viruses that cause around 5% of all cancers in humans, including almost all cervical cancer cases and a significant proportion of anogenital and oral cancers. The HPV oncoproteins E5, E6 and E7 manipulate cellular signalling pathways to evade the immune response and promote virus persistence. The Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway has emerged as a key mediator in a wide range of important biological signalling pathways, including cell proliferation, cell survival and the immune response. While STAT1 and STAT2 primarily drive immune signalling initiated by interferons, STAT3 and STAT5 have widely been linked to the survival and proliferative potential of a number of cancers. As such, the inhibition of STAT3 and STAT5 may offer a therapeutic benefit in HPV-associated cancers. In this review, we will discuss how HPV manipulates JAK/STAT signalling to evade the immune system and promote cell proliferation, enabling viral persistence and driving cancer development. We also discuss approaches to inhibit the JAK/STAT pathway and how these could potentially be used in the treatment of HPV-associated disease.

Tetraspanin CD9 affects HPV16 infection by modulating ADAM17 activity and the ERK signalling pathway

Human papillomaviruses (HPV) are causative agents of various tumours such as cervical cancer. HPV binding to the cell surface of keratinocytes leads to virus endocytosis at tetraspanin enriched microdomains. Complex interactions of the capsid proteins with host proteins as well as ADAM17-dependent ERK1/2 signal transduction enable the entry platform assembly of the oncogenic HPV type 16. Here, we studied the importance of tetraspanin CD9, also known as TSPAN29, in HPV16 infection of different epithelial cells. We found that both overexpression and loss of the tetraspanin decreased infection rates in cells with low endogenous CD9 levels, while reduction of CD9 expression in keratinocytes that exhibit high-CD9 protein amounts, led to an increase of infection. Therefore, we concluded that low-CD9 supports infection. Moreover, we found that changes in CD9 amounts affect the shedding of the ADAM17 substrate transforming growth factor alpha (TGFα) and the downstream phosphorylation of ERK. These effects correlate with those on infection rates suggesting that a specific CD9 optimum promotes ADAM17 activity, ERK signalling and virus infection. Together, our findings implicate that CD9 regulates HPV16 infection through the modulation of ADAM17 sheddase activity.

A Human Papillomavirus-Independent Cervical Cancer Animal Model Reveals Unconventional Mechanisms of Cervical Carcinogenesis

HPV infections are common in healthy women and only rarely cause cervical cancer, suggesting that individual genetic susceptibility may play a critical role in the establishment of persistent HPV infection and the development of cervical cancer. Here, we provide convincing in vitro and in vivo evidence showing that differential expression and activation of YAP1 oncogene determine individual susceptibility to HPV infection and cervical carcinogenesis. We found that hyperactivation of YAP1 in mouse cervical epithelium was sufficient to induce invasive cervical cancer. Cervical epithelial cell-specific HPV16 E6/E7 and YAP1 double-knockin mouse model demonstrated that high-risk HPV synergized with hyperactivated YAP1 to promote the initiation and progression of cervical cancer. Our mechanistic studies indicated that hyperactivation of YAP1 in cervical epithelial cells facilitated HPV infection by increasing the putative HPV receptor molecules and disrupting host cell innate immunity. Our finding reveals an unconventional mechanism for cervical carcinogenesis.

HPV infections are common in healthy women and only rarely cause cervical cancer. He et al. provide evidence that hyperactivation of the YAP1 oncogene can drive cervical cancer initiation and progression. YAP1 hyperactivation in cervical epithelial cells increases the HPV receptors and disrupts host cell innate immunity, facilitating HPV infection.