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Special Issue "Expert Views on HPV Infection"

A special issue of Viruses (ISSN 1999-4915). This special issue belongs to the section "Animal Viruses".

Deadline for manuscript submissions: closed (30 June 2017)

Special Issue Editors

Guest Editor
Dr. Alison A. McBride

Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
Website | E-Mail
Interests: Viral replication mechanisms, HPV, papillomaviruses, persistent infection, keratinocyte biology, host restriction factors, viral chromatin, genetic instability
Guest Editor
Dr. Karl Munger

Department of Developmental, Molecular and Chemical Biology Tufts University School of Medicine, Boston, MA 02111, USA
Website | E-Mail
Interests: Viral Oncology, HPV, papillomaviruses, persistent infections, keratinocyte biology, cellular chromatin, genomic instability, non-melanoma skin cancers

Special Issue Information

Dear Colleagues,

There are over two hundred different human papillomavirus (HPV) types, which replicate in mucosal and cutaneous stratified epithelial surfaces giving rise to a wide range of persistent lesions. A subset of these viruses are oncogenic and have been demonstrated to be the causative agent of approximately 5% human cancers. Papillomaviruses have a remarkable life style that relies on the differentiation state of the host epithelium; they infect the basal cells of the epithelium and establish a quiescent infection in the proliferative cells. As the infected cells differentiate, the productive life cycle is activated and virions are released from the surface of the epithelium. To support this life style, HPVs interact with, and manipulate, many key cellular pathways and the study of HPV infection has provided insight into many fundamental aspects of human biology. The goal of this Special Issue is to obtain expert viewpoints on unresolved, controversial or emerging topics related to the natural history, evolution, biology, and disease association of HPV infection.

Dr. Alison A. McBride
Dr. Karl Munger
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Viruses is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Human papillomavirus
  • Papillomaviruses
  • Oncogenic virus
  • Cancer

Published Papers (19 papers)

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Research

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Open AccessArticle The Enigmatic Origin of Papillomavirus Protein Domains
Viruses 2017, 9(9), 240; doi:10.3390/v9090240
Received: 18 July 2017 / Revised: 17 August 2017 / Accepted: 19 August 2017 / Published: 23 August 2017
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Abstract
Almost a century has passed since the discovery of papillomaviruses. A few decades of research have given a wealth of information on the molecular biology of papillomaviruses. Several excellent studies have been performed looking at the long- and short-term evolution of these viruses.
[...] Read more.
Almost a century has passed since the discovery of papillomaviruses. A few decades of research have given a wealth of information on the molecular biology of papillomaviruses. Several excellent studies have been performed looking at the long- and short-term evolution of these viruses. However, when and how papillomaviruses originate is still a mystery. In this study, we systematically searched the (sequenced) biosphere to find distant homologs of papillomaviral protein domains. Our data show that, even including structural information, which allows us to find deeper evolutionary relationships compared to sequence-only based methods, only half of the protein domains in papillomaviruses have relatives in the rest of the biosphere. We show that the major capsid protein L1 and the replication protein E1 have relatives in several viral families, sharing three protein domains with Polyomaviridae and Parvoviridae. However, only the E1 replication protein has connections with cellular organisms. Most likely, the papillomavirus ancestor is of marine origin, a biotope that is not very well sequenced at the present time. Nevertheless, there is no evidence as to how papillomaviruses originated and how they became vertebrate and epithelium specific. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessCommunication Molecular Mechanisms of Human Papillomavirus Induced Skin Carcinogenesis
Viruses 2017, 9(7), 187; doi:10.3390/v9070187
Received: 27 June 2017 / Revised: 7 July 2017 / Accepted: 7 July 2017 / Published: 14 July 2017
Cited by 1 | PDF Full-text (3109 KB) | HTML Full-text | XML Full-text
Abstract
Infection of the cutaneous skin with human papillomaviruses (HPV) of genus betapapillomavirus (βHPV) is associated with the development of premalignant actinic keratoses and squamous cell carcinoma. Due to the higher viral loads of βHPVs in actinic keratoses than in cancerous lesions, it is
[...] Read more.
Infection of the cutaneous skin with human papillomaviruses (HPV) of genus betapapillomavirus (βHPV) is associated with the development of premalignant actinic keratoses and squamous cell carcinoma. Due to the higher viral loads of βHPVs in actinic keratoses than in cancerous lesions, it is currently discussed that these viruses play a carcinogenic role in cancer initiation. In vitro assays performed to characterize the cell transforming activities of high-risk HPV types of genus alphapapillomavirus have markedly contributed to the present knowledge on their oncogenic functions. However, these assays failed to detect oncogenic functions of βHPV early proteins. They were not suitable for investigations aiming to study the interactive role of βHPV positive epidermis with mesenchymal cells and the extracellular matrix. This review focuses on βHPV gene functions with special focus on oncogenic mechanisms that may be relevant for skin cancer development. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Review

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Open AccessReview Why Human Papillomavirus Acute Infections Matter
Viruses 2017, 9(10), 293; doi:10.3390/v9100293
Received: 9 July 2017 / Revised: 25 September 2017 / Accepted: 2 October 2017 / Published: 10 October 2017
PDF Full-text (414 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Most infections by human papillomaviruses (HPVs) are `acute’, that is non-persistent. Yet, for HPVs, as for many other oncoviruses, there is a striking gap between our detailed understanding of chronic infections and our limited data on the early stages of infection. Here we
[...] Read more.
Most infections by human papillomaviruses (HPVs) are `acute’, that is non-persistent. Yet, for HPVs, as for many other oncoviruses, there is a striking gap between our detailed understanding of chronic infections and our limited data on the early stages of infection. Here we argue that studying HPV acute infections is necessary and timely. Focusing on early interactions will help explain why certain infections are cleared while others become chronic or latent. From a molecular perspective, descriptions of immune effectors and pro-inflammatory pathways during the initial stages of infections have the potential to lead to novel treatments or to improved handling algorithms. From a dynamical perspective, adopting concepts from spatial ecology, such as meta-populations or meta-communities, can help explain why HPV acute infections sometimes last for years. Furthermore, cervical cancer screening and vaccines impose novel iatrogenic pressures on HPVs, implying that anticipating any viral evolutionary response remains essential. Finally, hints at the associations between HPV acute infections and fertility deserve further investigation given their high, worldwide prevalence. Overall, understanding asymptomatic and benign infections may be instrumental in reducing HPV virulence. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Natural History of HPV Infection across the Lifespan: Role of Viral Latency
Viruses 2017, 9(10), 267; doi:10.3390/v9100267
Received: 24 August 2017 / Revised: 18 September 2017 / Accepted: 19 September 2017 / Published: 21 September 2017
PDF Full-text (739 KB) | HTML Full-text | XML Full-text
Abstract
Large-scale epidemiologic studies have been invaluable for elaboration of the causal relationship between persistent detection of genital human papillomavirus (HPV) infection and the development of invasive cervical cancer. However, these studies provide limited data to adequately inform models of the individual-level natural history
[...] Read more.
Large-scale epidemiologic studies have been invaluable for elaboration of the causal relationship between persistent detection of genital human papillomavirus (HPV) infection and the development of invasive cervical cancer. However, these studies provide limited data to adequately inform models of the individual-level natural history of HPV infection over the course of a lifetime, and particularly ignore the biological distinction between HPV-negative tests and lack of infection (i.e., the possibility of latent, undetectable HPV infection). Using data from more recent epidemiological studies, this review proposes an alternative model of the natural history of genital HPV across the life span. We argue that a more complete elucidation of the age-specific probabilities of the alternative transitions is highly relevant with the expanded use of HPV testing in cervical cancer screening. With routine HPV testing in cervical cancer screening, women commonly transition in and out of HPV detectability, raising concerns for the patient and the provider regarding the source of the positive test result, its prognosis, and effective strategies to prevent future recurrence. Alternative study designs and analytic frameworks are proposed to better understand the frequency and determinants of these transition pathways. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Mechanisms by which HPV Induces a Replication Competent Environment in Differentiating Keratinocytes
Viruses 2017, 9(9), 261; doi:10.3390/v9090261
Received: 31 August 2017 / Revised: 14 September 2017 / Accepted: 15 September 2017 / Published: 19 September 2017
PDF Full-text (2012 KB) | HTML Full-text | XML Full-text
Abstract
Human papillomaviruses (HPV) are the causative agents of cervical cancer and are also associated with other genital malignancies, as well as an increasing number of head and neck cancers. HPVs have evolved their life cycle to contend with the different cell states found
[...] Read more.
Human papillomaviruses (HPV) are the causative agents of cervical cancer and are also associated with other genital malignancies, as well as an increasing number of head and neck cancers. HPVs have evolved their life cycle to contend with the different cell states found in the stratified epithelium. Initial infection and viral genome maintenance occurs in the proliferating basal cells of the stratified epithelium, where cellular replication machinery is abundant. However, the productive phase of the viral life cycle, including productive replication, late gene expression and virion production, occurs upon epithelial differentiation, in cells that normally exit the cell cycle. This review outlines how HPV interfaces with specific cellular signaling pathways and factors to provide a replication-competent environment in differentiating cells. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Immunopathogenesis of HPV-Associated Cancers and Prospects for Immunotherapy
Viruses 2017, 9(9), 254; doi:10.3390/v9090254
Received: 25 August 2017 / Revised: 7 September 2017 / Accepted: 8 September 2017 / Published: 12 September 2017
PDF Full-text (1035 KB) | HTML Full-text | XML Full-text
Abstract
Human papillomavirus (HPV) infection is a causative factor for various cancers of the anogenital region and oropharynx, and is supposed to play an important cofactor role for skin carcinogenesis. Evasion from immunosurveillance favors viral persistence. However, there is evidence that the mere presence
[...] Read more.
Human papillomavirus (HPV) infection is a causative factor for various cancers of the anogenital region and oropharynx, and is supposed to play an important cofactor role for skin carcinogenesis. Evasion from immunosurveillance favors viral persistence. However, there is evidence that the mere presence of oncogenic HPV is not sufficient for malignant progression and that additional tumor-promoting steps are required. Recent studies have demonstrated that HPV-transformed cells actively promote chronic stromal inflammation and conspire with cells in the local microenvironment to promote carcinogenesis. This review highlights the complex interplay between HPV-infected cells and the local immune microenvironment during oncogenic HPV infection, persistence, and malignant progression, and discusses new prospects for diagnosis and immunotherapy of HPV-associated cancers. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Epigenetic Alterations in Human Papillomavirus-Associated Cancers
Viruses 2017, 9(9), 248; doi:10.3390/v9090248
Received: 14 August 2017 / Revised: 25 August 2017 / Accepted: 25 August 2017 / Published: 1 September 2017
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Abstract
Approximately 15–20% of human cancers are caused by viruses, including human papillomaviruses (HPVs). Viruses are obligatory intracellular parasites and encode proteins that reprogram the regulatory networks governing host cellular signaling pathways that control recognition by the immune system, proliferation, differentiation, genomic integrity, and
[...] Read more.
Approximately 15–20% of human cancers are caused by viruses, including human papillomaviruses (HPVs). Viruses are obligatory intracellular parasites and encode proteins that reprogram the regulatory networks governing host cellular signaling pathways that control recognition by the immune system, proliferation, differentiation, genomic integrity, and cell death. Given that key proteins in these regulatory networks are also subject to mutation in non-virally associated diseases and cancers, the study of oncogenic viruses has also been instrumental to the discovery and analysis of many fundamental cellular processes, including messenger RNA (mRNA) splicing, transcriptional enhancers, oncogenes and tumor suppressors, signal transduction, immune regulation, and cell cycle control. More recently, tumor viruses, in particular HPV, have proven themselves invaluable in the study of the cancer epigenome. Epigenetic silencing or de-silencing of genes can have cellular consequences that are akin to genetic mutations, i.e., the loss and gain of expression of genes that are not usually expressed in a certain cell type and/or genes that have tumor suppressive or oncogenic activities, respectively. Unlike genetic mutations, the reversible nature of epigenetic modifications affords an opportunity of epigenetic therapy for cancer. This review summarizes the current knowledge on epigenetic regulation in HPV-infected cells with a focus on those elements with relevance to carcinogenesis. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Keratinocyte Differentiation-Dependent Human Papillomavirus Gene Regulation
Viruses 2017, 9(9), 245; doi:10.3390/v9090245
Received: 7 August 2017 / Revised: 24 August 2017 / Accepted: 25 August 2017 / Published: 30 August 2017
Cited by 1 | PDF Full-text (1387 KB) | HTML Full-text | XML Full-text
Abstract
Human papillomaviruses (HPVs) cause diseases ranging from benign warts to invasive cancers. HPVs infect epithelial cells and their replication cycle is tightly linked with the differentiation process of the infected keratinocyte. The normal replication cycle involves an early and a late phase. The
[...] Read more.
Human papillomaviruses (HPVs) cause diseases ranging from benign warts to invasive cancers. HPVs infect epithelial cells and their replication cycle is tightly linked with the differentiation process of the infected keratinocyte. The normal replication cycle involves an early and a late phase. The early phase encompasses viral entry and initial genome replication, stimulation of cell division and inhibition of apoptosis in the infected cell. Late events in the HPV life cycle include viral genome amplification, virion formation, and release into the environment from the surface of the epithelium. The main proteins required at the late stage of infection for viral genome amplification include E1, E2, E4 and E5. The late proteins L1 and L2 are structural proteins that form the viral capsid. Regulation of these late events involves both cellular and viral proteins. The late viral mRNAs are expressed from a specific late promoter but final late mRNA levels in the infected cell are controlled by splicing, polyadenylation, nuclear export and RNA stability. Viral late protein expression is also controlled at the level of translation. This review will discuss current knowledge of how HPV late gene expression is regulated. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview The Mouse Papillomavirus Infection Model
Viruses 2017, 9(9), 246; doi:10.3390/v9090246
Received: 7 August 2017 / Revised: 23 August 2017 / Accepted: 24 August 2017 / Published: 30 August 2017
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Abstract
The mouse papillomavirus (MmuPV1) was first reported in 2011 and has since become a powerful research tool. Through collective efforts from different groups, significant progress has been made in the understanding of molecular, virological, and immunological mechanisms of MmuPV1 infections in both immunocompromised
[...] Read more.
The mouse papillomavirus (MmuPV1) was first reported in 2011 and has since become a powerful research tool. Through collective efforts from different groups, significant progress has been made in the understanding of molecular, virological, and immunological mechanisms of MmuPV1 infections in both immunocompromised and immunocompetent hosts. This mouse papillomavirus provides, for the first time, the opportunity to study papillomavirus infections in the context of a small common laboratory animal for which abundant reagents are available and for which many strains exist. The model is a major step forward in the study of papillomavirus disease and pathology. In this review, we summarize studies using MmuPV1 over the past six years and share our perspectives on the value of this unique model system. Specifically, we discuss viral pathogenesis in cutaneous and mucosal tissues as well as in different mouse strains, immune responses to the virus, and local host-restricted factors that may be involved in MmuPV1 infections and associated disease progression. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Roles of APOBEC3A and APOBEC3B in Human Papillomavirus Infection and Disease Progression
Viruses 2017, 9(8), 233; doi:10.3390/v9080233
Received: 26 July 2017 / Revised: 16 August 2017 / Accepted: 16 August 2017 / Published: 21 August 2017
Cited by 1 | PDF Full-text (1494 KB) | HTML Full-text | XML Full-text
Abstract
The apolipoprotein B messenger RNA-editing, enzyme-catalytic, polypeptide-like 3 (APOBEC3) family of cytidine deaminases plays an important role in the innate immune response to viral infections by editing viral genomes. However, the cytidine deaminase activity of APOBEC3 enzymes also induces somatic mutations in host
[...] Read more.
The apolipoprotein B messenger RNA-editing, enzyme-catalytic, polypeptide-like 3 (APOBEC3) family of cytidine deaminases plays an important role in the innate immune response to viral infections by editing viral genomes. However, the cytidine deaminase activity of APOBEC3 enzymes also induces somatic mutations in host genomes, which may drive cancer progression. Recent studies of human papillomavirus (HPV) infection and disease outcome highlight this duality. HPV infection is potently inhibited by one family member, APOBEC3A. Expression of APOBEC3A and APOBEC3B is highly elevated by the HPV oncoproteins E6 and E7 during persistent virus infection and disease progression. Furthermore, there is a high prevalence of APOBEC3A and APOBEC3B mutation signatures in HPV-associated cancers. These findings suggest that induction of an APOBEC3-mediated antiviral response during HPV infection may inadvertently contribute to cancer mutagenesis and virus evolution. Here, we discuss current understanding of APOBEC3A and APOBEC3B biology in HPV restriction, evolution, and associated cancer mutagenesis. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Targeting Persistent Human Papillomavirus Infection
Viruses 2017, 9(8), 229; doi:10.3390/v9080229
Received: 30 July 2017 / Revised: 30 July 2017 / Accepted: 15 August 2017 / Published: 18 August 2017
Cited by 2 | PDF Full-text (1478 KB) | HTML Full-text | XML Full-text
Abstract
While the majority of Human papillomavirus (HPV) infections are transient and cleared within a couple of years following exposure, 10–20% of infections persist latently, leading to disease progression and, ultimately, various forms of invasive cancer. Despite the clinical efficiency of recently developed multivalent
[...] Read more.
While the majority of Human papillomavirus (HPV) infections are transient and cleared within a couple of years following exposure, 10–20% of infections persist latently, leading to disease progression and, ultimately, various forms of invasive cancer. Despite the clinical efficiency of recently developed multivalent prophylactic HPV vaccines, these preventive measures are not effective against pre-existing infection. Additionally, considering that the burden associated with HPV is greatest in regions with limited access to preventative vaccination, the development of effective therapies targeting persistent infection remains imperative. This review discusses not only the mechanisms underlying persistent HPV infection, but also the promise of immunomodulatory therapeutic vaccines and small-molecular inhibitors, which aim to augment the host immune response against the viral infection as well as obstruct critical viral–host interactions. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Changing Stem Cell Dynamics during Papillomavirus Infection: Potential Roles for Cellular Plasticity in the Viral Lifecycle and Disease
Viruses 2017, 9(8), 221; doi:10.3390/v9080221
Received: 7 July 2017 / Revised: 7 August 2017 / Accepted: 8 August 2017 / Published: 12 August 2017
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Abstract
Stem cells and cellular plasticity are likely important components of tissue response to infection. There is emerging evidence that stem cells harbor receptors for common pathogen motifs and that they are receptive to local inflammatory signals in ways suggesting that they are critical
[...] Read more.
Stem cells and cellular plasticity are likely important components of tissue response to infection. There is emerging evidence that stem cells harbor receptors for common pathogen motifs and that they are receptive to local inflammatory signals in ways suggesting that they are critical responders that determine the balance between health and disease. In the field of papillomaviruses stem cells have been speculated to play roles during the viral life cycle, particularly during maintenance, and virus-promoted carcinogenesis but little has been conclusively determined. I summarize here evidence that gives clues to the potential role of stem cells and cellular plasticity in the lifecycle papillomavirus and linked carcinogenesis. I also discuss outstanding questions which need to be resolved. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Human Papillomavirus and the Stroma: Bidirectional Crosstalk during the Virus Life Cycle and Carcinogenesis
Viruses 2017, 9(8), 219; doi:10.3390/v9080219
Received: 30 June 2017 / Revised: 3 August 2017 / Accepted: 4 August 2017 / Published: 9 August 2017
Cited by 1 | PDF Full-text (1580 KB) | HTML Full-text | XML Full-text
Abstract
Human papillomaviruses (HPVs) are double-stranded DNA (dsDNA) tumor viruses that are causally associated with human cancers of the anogenital tract, skin, and oral cavity. Despite the availability of prophylactic vaccines, HPVs remain a major global health issue due to inadequate vaccine availability and
[...] Read more.
Human papillomaviruses (HPVs) are double-stranded DNA (dsDNA) tumor viruses that are causally associated with human cancers of the anogenital tract, skin, and oral cavity. Despite the availability of prophylactic vaccines, HPVs remain a major global health issue due to inadequate vaccine availability and vaccination coverage. The HPV life cycle is established and completed in the terminally differentiating stratified epithelia, and decades of research using in vitro organotypic raft cultures and in vivo genetically engineered mouse models have contributed to our understanding of the interactions between HPVs and the epithelium. More recently, important and emerging roles for the underlying stroma, or microenvironment, during the HPV life cycle and HPV-induced disease have become clear. This review discusses the current understanding of the bidirectional communication and relationship between HPV-infected epithelia and the surrounding microenvironment. As is the case with other human cancers, evidence suggests that the stroma functions as a significant partner in tumorigenesis and helps facilitate the oncogenic potential of HPVs in the stratified epithelium. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Exosomes and Other Extracellular Vesicles in HPV Transmission and Carcinogenesis
Viruses 2017, 9(8), 211; doi:10.3390/v9080211
Received: 7 July 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 7 August 2017
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Abstract
Extracellular vesicles (EVs), including exosomes (Exos), microvesicles (MVs) and apoptotic bodies (ABs) are released in biofluids by virtually all living cells. Tumor-derived Exos and MVs are garnering increasing attention because of their ability to participate in cellular communication or transfer of bioactive molecules
[...] Read more.
Extracellular vesicles (EVs), including exosomes (Exos), microvesicles (MVs) and apoptotic bodies (ABs) are released in biofluids by virtually all living cells. Tumor-derived Exos and MVs are garnering increasing attention because of their ability to participate in cellular communication or transfer of bioactive molecules (mRNAs, microRNAs, DNA and proteins) between neighboring cancerous or normal cells, and to contribute to human cancer progression. Malignant traits can also be transferred from apoptotic cancer cells to phagocytizing cells, either professional or non-professional. In this review, we focus on Exos and ABs and their relationship with human papillomavirus (HPV)-associated tumor development. The potential implication of EVs as theranostic biomarkers is also addressed. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Integration of Human Papillomavirus Genomes in Head and Neck Cancer: Is It Time to Consider a Paradigm Shift?
Viruses 2017, 9(8), 208; doi:10.3390/v9080208
Received: 30 June 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 3 August 2017
PDF Full-text (562 KB) | HTML Full-text | XML Full-text
Abstract
Human papillomaviruses (HPV) are detected in 70–80% of oropharyngeal cancers in the developed world, the incidence of which has reached epidemic proportions. The current paradigm regarding the status of the viral genome in these cancers is that there are three situations: one where
[...] Read more.
Human papillomaviruses (HPV) are detected in 70–80% of oropharyngeal cancers in the developed world, the incidence of which has reached epidemic proportions. The current paradigm regarding the status of the viral genome in these cancers is that there are three situations: one where the viral genome remains episomal, one where the viral genome integrates into the host genome and a third where there is a mixture of both integrated and episomal HPV genomes. Our recent work suggests that this third category has been mischaracterized as having integrated HPV genomes; evidence indicates that this category consists of virus–human hybrid episomes. Most of these hybrid episomes are consistent with being maintained by replication from HPV origin. We discuss our evidence to support this new paradigm, how such genomes can arise, and more importantly the implications for the clinical management of HPV positive head and neck cancers following accurate determination of the viral genome status. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Somatic Host Cell Alterations in HPV Carcinogenesis
Viruses 2017, 9(8), 206; doi:10.3390/v9080206
Received: 11 July 2017 / Revised: 24 July 2017 / Accepted: 25 July 2017 / Published: 3 August 2017
PDF Full-text (2013 KB) | HTML Full-text | XML Full-text
Abstract
High-risk human papilloma virus (HPV) infections cause cancers in different organ sites, most commonly cervical and head and neck cancers. While carcinogenesis is initiated by two viral oncoproteins, E6 and E7, increasing evidence shows the importance of specific somatic events in host cells
[...] Read more.
High-risk human papilloma virus (HPV) infections cause cancers in different organ sites, most commonly cervical and head and neck cancers. While carcinogenesis is initiated by two viral oncoproteins, E6 and E7, increasing evidence shows the importance of specific somatic events in host cells for malignant transformation. HPV-driven cancers share characteristic somatic changes, including apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC)-driven mutations and genomic instability leading to copy number variations and large chromosomal rearrangements. HPV-associated cancers have recurrent somatic mutations in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and phosphatase and tensin homolog (PTEN), human leukocyte antigen A and B (HLA-A and HLA-B)-A/B, and the transforming growth factor beta (TGFβ) pathway, and rarely have mutations in the tumor protein p53 (TP53) and RB transcriptional corepressor 1 (RB1) tumor suppressor genes. There are some variations by tumor site, such as NOTCH1 mutations which are primarily found in head and neck cancers. Understanding the somatic events following HPV infection and persistence can aid the development of early detection biomarkers, particularly when mutations in precancers are characterized. Somatic mutations may also influence prognosis and treatment decisions. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Telomerase Induction in HPV Infection and Oncogenesis
Viruses 2017, 9(7), 180; doi:10.3390/v9070180
Received: 15 June 2017 / Revised: 5 July 2017 / Accepted: 7 July 2017 / Published: 10 July 2017
PDF Full-text (481 KB) | HTML Full-text | XML Full-text
Abstract
Telomerase extends the repetitive DNA at the ends of linear chromosomes, and it is normally active in stem cells. When expressed in somatic diploid cells, it can lead to cellular immortalization. Human papillomaviruses (HPVs) are associated with and high-risk for cancer activate telomerase
[...] Read more.
Telomerase extends the repetitive DNA at the ends of linear chromosomes, and it is normally active in stem cells. When expressed in somatic diploid cells, it can lead to cellular immortalization. Human papillomaviruses (HPVs) are associated with and high-risk for cancer activate telomerase through the catalytic subunit of telomerase, human telomerase reverse transcriptase (hTERT). The expression of hTERT is affected by both high-risk HPVs, E6 and E7. Seminal studies over the last two decades have identified the transcriptional, epigenetic, and post-transcriptional roles high-risk E6 and E7 have in telomerase induction. This review will summarize these findings during infection and highlight the importance of telomerase activation as an oncogenic pathway in HPV-associated cancer development and progression. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessFeature PaperReview Virus/Host Cell Crosstalk in Hypoxic HPV-Positive Cancer Cells
Viruses 2017, 9(7), 174; doi:10.3390/v9070174
Received: 22 June 2017 / Revised: 22 June 2017 / Accepted: 29 June 2017 / Published: 5 July 2017
PDF Full-text (885 KB) | HTML Full-text | XML Full-text
Abstract
Oncogenic types of human papillomaviruses (HPVs) are major human carcinogens. The expression of the viral E6/E7 oncogenes plays a key role for HPV-linked oncogenesis. It recently has been found that low oxygen concentrations (“hypoxia”), as present in sub-regions of HPV-positive cancers,
[...] Read more.
Oncogenic types of human papillomaviruses (HPVs) are major human carcinogens. The expression of the viral E6/E7 oncogenes plays a key role for HPV-linked oncogenesis. It recently has been found that low oxygen concentrations (“hypoxia”), as present in sub-regions of HPV-positive cancers, strongly affect the interplay between the HPV oncogenes and their transformed host cell. As a result, a state of dormancy is induced in hypoxic HPV-positive cancer cells, which is characterized by a shutdown of viral oncogene expression and a proliferative arrest that can be reversed by reoxygenation. In this review, these findings are put into the context of the current concepts of both HPV-linked carcinogenesis and of the effects of hypoxia on tumor biology. Moreover, we discuss the consequences for the phenotype of HPV-positive cancer cells as well as for their clinical behavior and response towards established and prospective therapeutic strategies. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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Open AccessReview Deciphering the Multifactorial Susceptibility of Mucosal Junction Cells to HPV Infection and Related Carcinogenesis
Viruses 2017, 9(4), 85; doi:10.3390/v9040085
Received: 27 March 2017 / Revised: 13 April 2017 / Accepted: 18 April 2017 / Published: 20 April 2017
PDF Full-text (14372 KB) | HTML Full-text | XML Full-text
Abstract
Human papillomavirus (HPV)-induced neoplasms have long been considered to originate from viral infection of the basal cell layer of the squamous mucosa. However, this paradigm has been recently undermined by accumulating data supporting the critical role of a discrete population of squamo-columnar (SC)
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Human papillomavirus (HPV)-induced neoplasms have long been considered to originate from viral infection of the basal cell layer of the squamous mucosa. However, this paradigm has been recently undermined by accumulating data supporting the critical role of a discrete population of squamo-columnar (SC) junction cells in the pathogenesis of cervical (pre)cancers. The present review summarizes the current knowledge on junctional cells, discusses their high vulnerability to HPV infection, and stresses the potential clinical/translational value of the novel dualistic model of HPV-related carcinogenesis. Full article
(This article belongs to the Special Issue Expert Views on HPV Infection)
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