INFECTIOUS PAPILLOMATOSIS OF RABBITS : WITH A NOTE ON THE HISTOPATHOLOGY

The Enigmatic Origin of Papillomavirus Protein Domains

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.

Establishment of human metastatic colorectal cancer model in rabbit liver: A pilot study

Rationale and objectives

To develop a human metastatic colorectal cancer (mCRC) model in a rabbit liver.

Materials and methods

Immunosuppression in 4 adult New Zealand White rabbits weighing 3.5 to 4.5 kg was induced with daily subcutaneous injection of 15 mg/kg Cyclosporine A (CsA). On day 3 open mini-laparotomy was performed and 0.2 ml (1.8x10⁵ cells) suspension of HCT-116 and HT-29 human CRC cells were injected into the left and right medial lobe respectively. On day 10 the CsA dose was reduced to 10 mg/kg daily maintenance dose. Rabbits were weighed weekly, closely monitored for CsA side effects (weight loss, gingival hyperplasia and gut modification). Rabbits were sacrificed 5, 6, 7, and 8 weeks after cells injection. Liver tumors were collected for histopathology and immunohistochemical analysis.

Results

HT-29 Tumor growth was observed in 3 rabbits (75%). Tumors measured 3, 4 and 6 mm after 5, 6 and 8 weeks respectively. Microscopically, tumors contained hyperchromatic, pleomorphic cells that stained for monoclonal carcinoembryonic antigen (CEA), polyclonal CEA, cytokeratin 20, vascular markers (CD31, CD34), and vascular endothelial growth factor (VEGF) by immunohistochemistry, supporting involvement by the poorly differentiated HT-29 colorectal cancer cell line. No gross tumor growth or microscopic viability was observed from HCT-116 cell injection. CsA extra-hepatic manifestations included minimal gum hyperplasia and decrease in gut motility in 3 rabbits (75%), which was treated with Azithromycin 15 mg/kg and Cisapride 0.5 mg/kg every 12 hours, respectively.

Conclusion

We successfully developed a human metastatic colon cancer model in immunosuppressed rabbit liver using HT-29 cells.

The effect of paclitaxel-eluting covered metal stents versus covered metal stents in a rabbit esophageal squamous carcinoma model

BACKGROUND

The use of self-expanding metallic stents (SEMSs) is the current treatment of choice for malignant gastrointestinal obstructions. However, these stents can promote only drainage and have no antitumor effect. Some studies have reported that drug-eluting SEMSs may have tumor inhibition potential. The aim of this study was to evaluate the efficiency and safety of paclitaxel-eluting SEMSs (PEMSs) in rabbit esophageal cancer models.

MATERIALS AND METHODS

A PEMS was covered with a paclitaxel-incorporated membrane, in which the concentration of paclitaxel was 10% (wt/vol). The rabbit models were created endoscopically. Then, a PEMS or SEMS was endoscopically inserted into the rabbit esophagus. Two weeks after stent placement, the rabbits were sacrificed, and we evaluated the tumor volume, area of the wall defect, area of the tumor under endoscopic ultrasound (EUS) before and after stent placement, status of the proximal esophageal obstruction, tumor metastasis food-intake and weight loss.

RESULTS

A total of 26 rabbits received stent insertion and survived until sacrifice, and migration occurred in 4 cases, 3 in SEMS group and 1 in PEMS group. For the remaining 22 rabbits, at the sacrificed time, the average tumor volume was 7.00±4.30 cm3 in the SEMS group and 0.94±1.51 cm3 in the PEMS group (P<0.05). The area of the esophageal wall defect was 0.70±0.63 cm2 in the SEMS group and 0.17±0.16 cm2 in the PEMS group (P<0.05). The tumor area under EUS was 4.40±1.47 cm2 in the SEMS group and 1.30±1.06 cm2 in the PEMS group (P<0.05). At the time of stent placement, tumor area under EUS was comparable in the two groups. Other indices did not significantly differ between the two groups.

CONCLUSIONS

SEMS and PEMS are both safe and effective to relieve dysphagia in rabbit esophageal cancer models. A PEMS can serve as an alternative tool for advanced esophageal cancer that may inhibit tumor growth by serving as a drug sustained-release platform. Clinical trials of the stent are warranted in the future.

Papillomaviruses: a systematic review

In the last decades, a group of viruses has received great attention due to its relationship with cancer development and its wide distribution throughout the vertebrates: the papillomaviruses. In this article, we aim to review some of the most relevant reports concerning the use of bovines as an experimental model for studies related to papillomaviruses. Moreover, the obtained data contributes to the development of strategies against the clinical consequences of bovine papillomaviruses (BPV) that have led to drastic hazards to the herds. To overcome the problem, the vaccines that we have been developing involve recombinant DNA technology, aiming at prophylactic and therapeutic procedures. It is important to point out that these strategies can be used as models for innovative procedures against HPV, as this virus is the main causal agent of cervical cancer, the second most fatal cancer in women.

Rabbit Oncology: Diseases, Diagnostics, and Therapeutics

Neoplasia has long been reported as a rare finding in rabbits, but over the past decades the number of reports on neoplastic disease in rabbits has risen considerably. Similar to other animals, neoplastic changes may occur in any organ system, but the rate in which the organ systems are affected differs considerably. In rabbits, tumors have predominantly been found in the urogenital, hemolymphatic, and integumentary systems. This article discusses current insights on the etiopathogenesis, clinical signs, diagnosis, and treatment of the commonest neoplastic diseases in rabbits and offer guidelines for the correct diagnosis and treatment of the rabbit oncologic patient.

Overview of Infectious Causes of Human Cancers

Emerging evidence has demonstrated that almost each person is infected at least one potentially cancer-causing organism; however, only a small proportion of infected individual develops cancer. In this review, to elucidate the potential role of infectious organisms in the development and progression of human cancers, we summarize the previous history and current understandings of infection-associated cancers and highlight the common molecular mechanisms of cancers caused by infectious agents and their potential cofactors, which may bring us to effectively prevent and reduce the infection-associated cancers in the future.

Recent advances in preclinical model systems for papillomaviruses

Preclinical model systems to study multiple features of the papillomavirus life cycle have greatly aided our understanding of Human Papillomavirus (HPV) biology, disease progression and treatments. The challenge to studying HPV in hosts is that HPV along with most PVs are both species and tissue restricted. Thus, fundamental properties of HPV viral proteins can be assessed in specialized cell culture systems but host responses that involve innate immunity and host restriction factors requires preclinical surrogate models. Fortunately, there are several well-characterized and new animal models of papillomavirus infections that are available to the PV research community. Old models that continue to have value include canine, bovine and rabbit PV models and new rodent models are in place to better assess host-virus interactions. Questions arise as to the strengths and weaknesses of animal PV models for HPV disease and how accurately these preclinical models predict malignant progression, vaccine efficacy and therapeutic control of HPV-associated disease. In this review, we examine current preclinical models and highlight the strengths and weaknesses of the various models as well as provide an update on new opportunities to study the numerous unknowns that persist in the HPV research field.

Control of viral replication and transcription by the papillomavirus E8^E2 protein

Human papillomaviruses have adjusted their replication levels to the differentiation state of the infected keratinocyte. PV genomes replicate in undifferentiated cells at low levels and to high levels in differentiated cells. Genome replication requires the viral E1 helicase and the viral E2 transcription/replication activator. The limited replication in undifferentiated cells is predominantly due to the expression of the highly conserved E8^E2 viral repressor protein, which is a fusion between E8 and the C-terminal half of the E2 protein. E8^E2 is a sequence-specific DNA binding protein that inhibits viral gene expression and viral genome replication. The E8 domain is required for repression activities, which are mainly due to the interaction with cellular NCoR/SMRT corepressor complexes. In the case of HPV16, the most carcinogenic HPV type, E8^E2 not only limits genome replication in undifferentiated cells but also productive replication in differentiated epithelium. E8^E2 is expressed from a separate promoter that is controlled by unknown cellular factors and the viral transcription and replication regulators E1, E2 and E8^E2. In summary, E8^E2 is an important negative regulator whose levels may be critical for the outcome of HPV infections.

Viral Carcinogenesis

Cancer has been recognized for thousands of years. Egyptians believed that cancer occurred at the will of the gods. Hippocrates believed human disease resulted from an imbalance of the four humors: blood, phlegm, yellow bile, and black bile with cancer being caused by excess black bile. The lymph theory of cancer replaced the humoral theory and the blastema theory replaced the lymph theory. Rudolph Virchow was the first to recognize that cancer cells like all cells came from other cells and believed chronic irritation caused cancer. At the same time there was a belief that trauma caused cancer, though it never evolved after many experiments inducing trauma. The birth of virology occurred in 1892 when Dimitri Ivanofsky demonstrated that diseased tobacco plants remained infective after filtering their sap through a filter that trapped bacteria. Martinus Beijerinck would call the tiny infective agent a virus and both Dimitri Ivanofsky and Marinus Beijerinck would become the fathers of virology. Not to long thereafter, Payton Rous founded the field of tumor virology in 1911 with his discovery of a transmittable sarcoma of chickens by what would come to be called Rous sarcoma virus or RSV for short. The first identified human tumor virus was the Epstein-Barr virus (EBV), named after Tony Epstein and Yvonne Barr who visualized the virus particles in Burkitt's lymphoma cells by electron microscopy in 1965. Since that time, many viruses have been associated with carcinogenesis including the most studied, human papilloma virus associated with cervical carcinoma, many other anogenital carcinomas, and oropharyngeal carcinoma. The World Health Organization currently estimates that approximately 22% of worldwide cancers are attributable to infectious etiologies, of which viral etiologies is estimated at 15-20%. The field of tumor virology/viral carcinogenesis has not only identified viruses as etiologic agents of human cancers, but has also given molecular insights to all human cancers including the oncogene activation and tumor suppressor gene inactivation.

Human papillomavirus molecular biology

Human papillomaviruses are small DNA viruses with a tropism for squamous epithelia. A unique aspect of human papillomavirus molecular biology involves dependence on the differentiation status of the host epithelial cell to complete the viral lifecycle. A small group of these viruses are the etiologic agents of several types of human cancers, including oral and anogenital tract carcinomas. This review focuses on the basic molecular biology of human papillomaviruses.

In vitro and Animal Models for Antiviral Therapy in Papillomavirus Infections

The need for antiviral therapies for papillomavirus infections is well recognized but the difficulties of reproducing the infectious cycle of papillomaviruses in vitro has hindered our understanding of virus-cell interactions and the regulation of viral gene expression during permissive growth. Recent advances in understanding the temporal expression and function of papillomavirus proteins has enabled consideration of a targeted approach to papillomavirus chemotherapy and in particular the inhibition of viral replication by targeting the E1 and E2 proteins. There are in vitro culture systems available for the screening of new chemotherapeutic agents, since significant advances have been made with culture systems which promote epithelial differentiation in vitro. However, to date, there are no published data which show that virions generated in vitro can infect keratinocytes and initiate another round of replication in vitro. In vivo animal models are therefore necessary to assess the efficacy of antivirals in preventing and treating viral infection, particularly for the low-risk genital viruses which are on the whole refractory to culture in vitro. Although papillomaviruses affect a wide variety of hosts in a species-specific manner, the animals most useful for modelling papillomavirus infections include the rabbit, ox, mouse, dog, horse, primate and sheep. The ideal animal model should be widely available, easy to house and handle, be large enough to allow for adequate tissue sampling, develop lesions on anatomical sites comparable with those in human diseases and these lesions should be readily accessible for monitoring and ideally should yield large amounts of infectious virus particles for use in both in vivo and in vitro studies. The relative merits of the various papillomavirus animal models available in relation to these criteria are discussed.

Infection and cancer in multicellular organisms

Evolutionary considerations suggest that oncogenic infections should be pervasive among animal species. Infection-associated cancers are well documented in humans and domestic animals, less commonly reported in undomesticated captive animals, and rarely documented in nature. In this paper, we review the literature associating infectious agents with cancer to evaluate the reasons for this pattern. Non-malignant infectious neoplasms occur pervasively in multicellular life, but oncogenic progression to malignancy is often uncertain. Evidence from humans and domestic animals shows that non-malignant infectious neoplasms can develop into cancer, although generally with low frequency. Malignant neoplasms could be difficult to find in nature because of a low frequency of oncogenic transformation, short survival after malignancy and reduced survival prior to malignancy. Moreover, the evaluation of malignancy can be ambiguous in nature, because criteria for malignancy may be difficult to apply consistently across species. The information available in the literature therefore does not allow for a definitive assessment of the pervasiveness of infectious cancers in nature, but the presence of infectious neoplasias and knowledge about the progression of benign neoplasias to cancer is consistent with a widespread but largely undetected occurrence.

Genotype-specific concordance of oral and genital human papillomavirus infections among marital couples is low

Data on genotype-specific concordance of oral-oral and genital-oral HPV infections among marital couples are key to understand HPV transmission between spouses. Genotype-specific concordance of HPV infections (oral/genital) and their co-variates among 131 marital couples were determined during 6-year follow-up (FU). Seven oral scrapings were taken from both spouses, accompanied by six genital samplings from the women and one (at baseline) from the male partners. HPV-genotyping was performed by nested PCR and a Luminex®-based Multimetrix Assay. Demographic data were collected with questionnaires at baseline and study conclusion. Prevalence of oral HPV varied from 10.3 to 27.0 % and 15.8 to 31.3 % in women and men, respectively. At baseline, 37.6 % of the male genital samples were HPV-positive while in female genital samples, HPV prevalence varied from 13.3 to 59.4 %. Only 15 couples had HPV genotype-specific concordance (oral-oral n = 7; male oral-female genital n = 9; female oral-male genital n = 2). In the nested case-control setting, higher number of deliveries (OR 0.145, 95%CI 0.030-0.706, p = 0.017) and higher number of intercourse (OR 0.488, 95%CI 0.243-0.978, p = 0.043) decreased the likelihood of concordant HPV infections while practicing oral sex increased the risk (OR 0.299, 95%CI 0.120-0.748, p = 0.010). In multivariate analysis, the likelihood of concordance was decreased by higher number of pregnancies of the female partner (p = 0.020) and by higher frequency of intercourse reported by the male spouse (p = 0.027). To conclude, asymptomatic HPV infections were common in both spouses while genotype-specific concordance was low. This supports the view that HPV profile of the spouses has been established before the current marital relationship.

Historical review of the causes of cancer

In the early 1900s, numerous seminal publications reported that high rates of cancer occurred in certain occupations. During this period, work with infectious agents produced only meager results which seemed irrelevant to humans. Then in the 1980s ground breaking evidence began to emerge that a variety of viruses also cause cancer in humans. There is now sufficient evidence of carcinogenicity in humans for human T-cell lymphotrophic virus, human immunodeficiency virus, hepatitis B virus, hepatitis C virus, human papillomavirus, Epstein-Barr virus, and human herpes virus 8 according to the International Agency for Research on Cancer (IARC). Many other causes of cancer have also been identified by the IARC, which include: Sunlight, tobacco, pharmaceuticals, hormones, alcohol, parasites, fungi, bacteria, salted fish, wood dust, and herbs. The World Cancer Research Fund and the American Institute for Cancer Research have determined additional causes of cancer, which include beta carotene, red meat, processed meats, low fibre diets, not breast feeding, obesity, increased adult height and sedentary lifestyles. In brief, a historical review of the discoveries of the causes of human cancer is presented with extended discussions of the difficulties encountered in identifying viral causes of cancer.

Significance, cytomorphology of decoy cells in polyomavirus-associated nephropathy: Review of clinical, histopathological, and virological correlates with commentary

Human polyomaviruses (PyV) are ubiquitous, remaining predominantly inactive hence asymptomatic in the healthy, immunocompetent population. BK and JC PyV potentially infect pan-urinary tract epithelial cells. With reactivation, PyV disrupt cell cycling mechanisms, facilitating viral replication leading to cell necrosis, exfoliation, and, infrequently, carcinogenesis. Exfoliated PyV-infected cells pose diagnostic pitfalls, hence they are termed "decoy cells" as they may mimic high-grade urothelial carcinoma cells. BK polyomavirus-associated-nephropathy (BKVAN) is an inflammatory disease causing interstitial fibrosis with tubular atrophy in renal transplant recipients, increasing risk of graft loss. BKVAN is confirmed by renal biopsy, and managed by immunosuppression modulation. As voided urine may provide pan-reno-urinary tract sampling, cytopathology may serve a critical diagnostic purpose coupled with decoy cell quantification and indirect BK PyV load gauging. Thus, identification of decoy cells and differentiation from high-grade urothelial carcinoma cells, and degenerated, benign urothelial cells, is clinically essential. PyV virology and pathobiology in the context of renal transplantation, immuno-suppression and BKVAN, and, decoy cell cytomorphology and cytopreparation with commentary are highlighted. Decoy cell overall characteristics: variable degeneration; cytomegaly; comet-like shapes; angular cytoplasmic extensions; eccentric, polar nuclear placements; moderate anisocytosis; typically single cells with high N:C ratios. Cytoplasmic features: moderate-abundance; granular, blue-gray monochromatism. Nuclear features: karyomegaly; haphazardly-scattered chromatin densities; smudged, homogeneous, basophilic ground glass masses displacing chromatin alongside inner periphery of regular, symmetrical nuclear envelopes. Background features: granular cellular debris; inflammatory cells; intact and lyzed erythrocytes. Decoy cells lack coarse chromatin as in high-grade urothelial carcinoma cells. Benign urothelial cells exhibit low N:C ratios with fine chromatin distribution and euchromasia.

Mutagenic Potential ofBos taurus Papillomavirus Type 1 E6 Recombinant Protein: First Description

Bovine papillomavirus (BPV) is considered a useful model to study HPV oncogenic process. BPV interacts with the host chromatin, resulting in DNA damage, which is attributed to E5, E6, and E7 viral oncoproteins activity. However, the oncogenic mechanisms of BPV E6 oncoprotein per se remain unknown. This study aimed to evaluate the mutagenic potential of Bos taurus papillomavirus type 1 (BPV-1) E6 recombinant oncoprotein by the cytokinesis-block micronucleus assay (CBMNA) and comet assay (CA). Peripheral blood samples of five calves were collected. Samples were subjected to molecular diagnosis, which did not reveal presence of BPV sequences. Samples were treated with 1 μg/mL of BPV-1 E6 oncoprotein and 50 μg/mL of cyclophosphamide (positive control). Negative controls were not submitted to any treatment. The samples were submitted to the CBMNA and CA. The results showed that BPV E6 oncoprotein induces clastogenesis per se, which is indicative of genomic instability. These results allowed better understanding the mechanism of cancer promotion associated with the BPV E6 oncoprotein and revealed that this oncoprotein can induce carcinogenesis per se. E6 recombinant oncoprotein has been suggested as a possible vaccine candidate. Results pointed out that BPV E6 recombinant oncoprotein modifications are required to use it as vaccine.

Relevance of Rabbit VX2 Tumor Model for Studies on Human Hepatocellular Carcinoma: A MicroRNA-Based Study

MicroRNAs are small (~22 nt), noncoding RNA molecules that have critical cellular functions in proliferation, differentiation, angiogenesis and apoptosis. miRNA expression profiling has been used to create signatures of solid tumors and, in many cases, it has been shown to correlate with the severity of the disease. The rabbit VX2 tumor model has been used widely to study a number of human cancers. Our objective in this study is to generate an miRNA signature of the VX2 tumor and to identify miRNAs that are highly expressed in this aggressive tumor. In this study, we performed miRNA profiling of the rabbit VX2 tumor using a microarray that has probes for 1292 unique miRNAs. Their expression in tumor samples was quantified and analyzed. We found that 35 miRNAs were significantly up-regulated in the VX2 tumor. Among these, 13 human miRNAs and eight members of the let-7 family were previously identified in cancers. In addition, we show that the expression of three miRNAs (miR-923, miR-1275, and miR-1308) is novel for the rabbit VX2 tumor, and their expression was not previously shown to be associated with any type of cancer. For the first time, we show the miRNA signature profile for a solid tumor in a rabbit model. miRNAs highly expressed in the VX2 tumor may serve as novel candidates for molecular biomarkers and as potential drug targets.

Nanomedical innovation: the SEON-concept for an improved cancer therapy with magnetic nanoparticles

Nanomedicine offers tremendous opportunities for the development of novel therapeutic and diagnostic tools. During the last decades, extensive knowledge was gained about stabilizing and the coating of nanoparticles, their functionalization for drug binding and drug release and possible strategies for therapies and diagnostics of different diseases. Most recently, more and more emphasis has been placed on nanotoxicology and nanosafety aspects. The section of experimental oncology and nanomedicine developed a concept for translating this knowledge into clinical application of magnetic drug targeting for the treatment of cancer and other diseases using superparamagnetic iron oxide nanoparticles. This approach includes reproducible synthesis, detailed characterization, nanotoxicological testing, evaluation in ex vivo models, preclinical animal studies and production of superparamagnetic iron oxide nanoparticles according to good manufacturing practice regulations.

Delayed and Aberrant Presentation of VX2 Carcinoma in a Rabbit Model of Hepatic Neoplasia

A socially-housed New Zealand white rabbit presented with a large subcutaneous mass on the ventral thorax approximately 11 mo after the intrahepatic delivery of a suspension of VX2 carcinoma cells to induce hepatocellular carcinoma as part of a nanoparticle study. The mass and closely associated axillary lymph node were removed en bloc. Immunohistochemical staining identified the mass as an undifferentiated carcinoma. The rabbit demonstrated no appreciable pathology at the study end point at 16 mo after VX2 inoculation. An additional rabbit from the same VX2 injection cohort was found at necropsy to have an unanticipated intraabdominal mass, also identified as an undifferentiated carcinoma. This case report summarizes the molecular analysis of both tumors through a novel PCR assay, which identified the delayed and aberrant onset of VX2 carcinoma in an extended timeframe not previously reported.

Animal models for photodynamic therapy (PDT)

Photodynamic therapy (PDT) combines visible light and photosensitizing dyes. Different animal models have been used to test PDT for cancer, infectious disease and cardiovascular disease. Mouse models of tumours include subcutaneous, orthotopic, syngeneic, xenograft, autochthonous and genetically modified.

Photodynamic therapy (PDT) employs non-toxic dyes called photosensitizers (PSs), which absorb visible light to give the excited singlet state, followed by the long-lived triplet state that can undergo photochemistry. In the presence of ambient oxygen, reactive oxygen species (ROS), such as singlet oxygen and hydroxyl radicals are formed that are able to kill cancer cells, inactivate microbial pathogens and destroy unwanted tissue. Although there are already several clinically approved PSs for various disease indications, many studies around the world are using animal models to investigate the further utility of PDT. The present review will cover the main groups of animal models that have been described in the literature. Cancer comprises the single biggest group of models including syngeneic mouse/rat tumours that can either be subcutaneous or orthotopic and allow the study of anti-tumour immune response; human tumours that need to be implanted in immunosuppressed hosts; carcinogen-induced tumours; and mice that have been genetically engineered to develop cancer (often by pathways similar to those in patients). Infections are the second biggest class of animal models and the anatomical sites include wounds, burns, oral cavity, ears, eyes, nose etc. Responsible pathogens can include Gram-positive and Gram-negative bacteria, fungi, viruses and parasites. A smaller and diverse group of miscellaneous animal models have been reported that allow PDT to be tested in ophthalmology, atherosclerosis, atrial fibrillation, dermatology and wound healing. Successful studies using animal models of PDT are blazing the trail for tomorrow's clinical approvals.

Modulation of therapeutic sensitivity by human papillomavirus

Human papillomaviruses (HPVs) are small double-stranded DNA viruses that pose significant public health concerns as the causative agent of approximately 5% of worldwide cancers. The HPV oncogenes E6 and E7 play key roles in carcinogenesis. In the last 15years there has been a significant increase in the incidence of HPV-related head and neck cancers arising primarily in the oropharynx. Patients with HPV-positive head and neck cancers (HNCs) have a significantly improved prognosis compared to those with HPV-negative disease. In this review we will discuss data suggesting how HPV oncogenes modulate both the intrinsic radiation sensitivity of HNCs and also have important effects upon the tumor microenvironment. Together, these findings contribute to the improved outcomes seen in patients with HPV-positive HNC.

Interaction of human papillomavirus type 16 particles with heparan sulfate and syndecan-1 molecules in the keratinocyte extracellular matrix plays an active role in infection

Oncogenic human papillomaviruses (HPVs) attach predominantly to extracellular matrix (ECM) components during infection of cultured keratinocytes and in the rodent vaginal challenge model in vivo. However, the mechanism of virion transfer from the ECM to receptors that mediate entry into host cells has not been determined. In this work we strove to assess the role of heparan sulfate (HS) chains in HPV16 binding to the ECM and determine how HPV16 release from the ECM is regulated. We also assessed the extent to which capsids released from the ECM are infectious. We show that a large fraction of HPV16 particles binds to the ECM via HS chains, and that syndecan-1 (snd-1) molecules present in the ECM are involved in virus binding. Inhibiting the normal processing of snd-1 and HS molecules via matrix metalloproteinases and heparanase dramatically reduces virus release from the ECM, cellular uptake and infection. Conversely, exogenous heparinase activates each of these processes. We confirm that HPV16 released from the ECM is infectious in keratinocytes. Use of a specific inhibitor shows furin is not involved in HPV16 release from ECM attachment factors and corroborates other studies showing only the intracellular activity of furin is responsible for modulating HPV infectivity. These data suggest that our recently proposed model, describing the action of HS proteoglycan processing enzymes in releasing HPV16 from the cell surface in complex with the attachment factor snd-1, is also relevant to the release of HPV16 particles from the ECM to promote efficient infection of keratinocytes.

A Century of Shope Papillomavirus in Museum Rabbit Specimens

Sylvilagus floridanus Papillomavirus (SfPV) causes growth of large horn-like tumors on rabbits. SfPV was described in cottontail rabbits (probably Sylvilagus floridanus) from Kansas and Iowa by Richard Shope in 1933, and detected in S. audubonii in 2011. It is known almost exclusively from the US Midwest. We explored the University of Kansas Natural History Museum for historical museum specimens infected with SfPV, using molecular techniques, to assess if additional wild species host SfPV, and whether SfPV occurs throughout the host range, or just in the Midwest. Secondary aims were to detect distinct strains, and evidence for strain spatio-temporal specificity. We found 20 of 1395 rabbits in the KU collection SfPV symptomatic. Three of 17 lagomorph species (S. nuttallii, and the two known hosts) were symptomatic, while Brachylagus, Lepus and eight additional Sylvilagus species were not. 13 symptomatic individuals were positive by molecular testing, including the first S. nuttallii detection. Prevalence of symptomatic individuals was significantly higher in Sylvilagus (1.8%) than Lepus. Half of these specimens came from Kansas, though new molecular detections were obtained from Jalisco—Mexico’s first—and Nebraska, Nevada, New Mexico, and Texas, USA. We document the oldest lab-confirmed case (Kansas, 1915), pre-dating Shope’s first case. SfPV amplification was possible from 63.2% of symptomatic museum specimens. Using multiple methodologies, rolling circle amplification and, multiple isothermal displacement amplification in addition to PCR, greatly improved detection rates. Short sequences were obtained from six individuals for two genes. L1 gene sequences were identical to all previously detected sequences; E7 gene sequences, were more variable, yielding five distinct SfPV1 strains that differing by less than 2% from strains circulating in the Midwest and Mexico, between 1915 and 2005. Our results do not clarify whether strains are host species specific, though they are consistent with SfPV specificity to genus Sylvilagus.

Nuns, warts, viruses, and cancer

It has been known for more than 150 years that the risk of carcinoma of the uterine cervix correlates with the number of sexual partners. Laboratory and epidemiological evidence demonstrated that infection with certain human papillomavirus (HPV) types initiates the vast majority of, if not all, cervical cancer, as well as a substantial fraction of other cancers, including other anogenital cancer and oropharyngeal cancer. Pap smear testing resulted in a dramatic reduction in the incidence of cervical cancer in the developed world, and HPV vaccination has the potential to eradicate HPV-associated cancer worldwide and represents a major public health breakthrough. The major current challenge is to ensure that HPV vaccines are widely administered.

Intraperitoneal oxidative stress as an oncolytic immunomodulator?

Intraperitoneal oxidative stress effectively converts the immune response against the papillomavirus-associated rabbit VX2 carcinoma from tumor permissive to tumoricidal and leads to a sustainable oncolytic immune response that can be adoptively transferred.

Percutaneous ultrasound guided implantation of VX2 for creation of a rabbit hepatic tumor model

Creation of a VX2 tumor model has traditionally required a laparotomy and surgical implantation of tumor fragments. Open surgical procedures are invasive and require long procedure times and recovery that can result in post-operative morbidity and mortality. The purpose of this study is to report the results of a percutaneous ultrasound guided method for creation of a VX2 model in rabbit livers. A total of 27 New Zealand white rabbits underwent a percutaneous ultrasound guided approach, where a VX2 tumor fragment was implanted in the liver. Magnetic resonance imaging was used to assess for tumor growth and necropsy was performed to determine rates of tract seeding and metastatic disease. Ultrasound guided tumor implantation was successful in all 27 rabbits. One rabbit died 2 days following the implantation procedure. Two rabbits had no tumors seen on follow-up imaging. Therefore, tumor development was seen in 24/26 (92%) rabbits. During the follow-up period, tract seeding was seen in 8% of rabbits and 38% had extra-hepatic metastatic disease. Therefore, percutaneous ultrasound guided tumor implantation safely provides reliable tumor growth for establishing hepatic VX2 tumors in a rabbit model with decreased rates of tract seeding, compared to previously reported methods.

Study on the diagnosis of rabbit VX2 esophageal cancer and stent-therapy efficacy based on multiphoton microscopy

Histopathology is the gold standard for diagnosis of esophageal carcinoma. Based on two photon excited fluorescence (TPEF) and second harmonic generation (SHG), multiphoton microscopy (MPM) has become a novel optical tool adjunct to current histopathological techniques without any exogenous contrast agents. We thus investigated the potential of using TPEF and SHG techniques for differentiating cancer tissues from cancer tissues after paclitaxel-eluting stent implantation and normal esophageal tissues which are fresh and unstained without dying from the VX2 esophageal carcinoma rabbit models. Comparisons were made between MPM imaging and gold standard sections for each specimen stained with hematoxylin-eosin (H&E). Our results indicated that the MPM imaging technique could identify and distinguish among normal esophageal tissues, cancer tissues, as well as cancer tissues after stent implantation. Therefore, MPM potentially offers a powerful tool to not only diagnose esophageal cancer but also monitor stent-therapy efficacy.

Effect of ischemia reperfusion on rabbit VX2 cells in a hepatocellular carcinoma model

BACKGROUND

We established a rabbit VX2 cell liver carcinoma model to evaluate effects of ischemia reperfusion (IR) on reactive oxygen species (ROS) development and liver cell apoptosis rates.

METHODS

Thirty-six rabbits were divided into a control (n=6) and a VX2 hepatocellular carcinoma (HCC) model group (n=30), which received VX2 cell suspension injections into their livers. From the 30 HCC rabbits, 6 rabbits served as control without hepatic ischemia and the rest were treated with hepatic artery and portal vein clamps for 60 minutes. At 1 hour, 1 day, 3 days and 7 days of reperfusion, 6 rabbits were sacrificed and changes of catalase (CAT) and super-oxide dismutase (SOD) activities as well as apoptosis rates, measured by TUNEL assays, were compared between tumor tissues, normal tumor surrounding hepatic tissues and controls.

RESULTS

All treated animals developed liver tumors. The CAT activity increased in both tissues 1 hour after reperfusion (P < 0.05) and dropped to low levels in the hepatocarcinoma cells at day 1 after reperfusion (P < 0.01), but increased to higher levels than the control on day 3 (P < 0.05). SOD activity decreased significantly in both tissues until day 1 after reperfusion and kept low in the hepatocarcinoma cells until day 7 (P < 0.05). The apoptosis rates after IR increased more in cancer than in normal hepatic tissues (P < 0.01).

CONCLUSION

Injection of VX2 tumor cell suspension into rabbit liver parenchyma achieved good results for creating a liver tumor model. IR induced apoptosis of tumor tissue and normal hepatic tissues via ROS development.

Gordon Wilson Lecture: Infectious Disease Causes of Cancer: Opportunities for Prevention and Treatment

The role of infectious agents in cancer is generally underappreciated. However, approximately 20% of human cancers are caused by infectious agents and as such they rank second only to tobacco as a potentially preventable cause in humans. Specific viruses, parasites, and bacteria have been linked to specific human cancers. The infectious etiology for these specific cancers provides opportunities for prevention and treatment.

Rabbit hepatic arterial anatomy variations: implications on experimental design

BACKGROUND

The VX2 rabbit model of liver cancer is commonly used to evaluate the efficacy of locoregional anticancer therapy and knowledge of the hepatic arterial anatomy in the rabbit is important for catheter-directed experiments.

PURPOSE

To describe the normal anatomy and anatomic variations of the celiac axis and hepatic artery in the rabbit.

MATERIAL AND METHODS

Angiograms of 222 rabbits were retrospectively reviewed. The branching pattern of the celiac axis was classified and the diameters of the major branches were measured. Paired t-tests were used to compare the difference between the average sizes of arteries.

RESULTS

Variant celiac axis or hepatic artery anatomy was noted in 25.9% of angiograms, with the gastric branches arising from the proper hepatic artery in 23.3% of cases. The celiac axis could be successfully classified into one of five distinct branching patterns in 193 (86.9%) cases. The mean diameters of the right and left hepatic arteries were 0.67 mm (95% CI [0.64, 0.7]) and 1.25 mm (95% CI [1.19, 1.31]), respectively. The mean diameters of the medial and lateral branches of the left hepatic artery were 0.63 mm (95% CI [0.6, 0.67]) and 0.91 mm (95% CI [0.86, 0.96]), respectively. The right hepatic artery was significantly smaller than the left hepatic artery and the lateral branch of the left hepatic artery (all P values <0.0001).

CONCLUSION

Arterial variants in the rabbit are not uncommon. The proper hepatic artery often gives origin to gastric artery branches. To facilitate superselective intra-arterial intervention, the left lateral lobe of the liver should be targeted for tumor implantation because of the significant size difference between the right and left hepatic arteries.

Human papillomavirus vaccination: a case study in translational science

Each year 610,000 cases of anogenital and oropharyngeal cancers caused by human papillomavirus (HPV) occur worldwide. HPV vaccination represents a promising opportunity to prevent cancer on a global scale. The vaccine's story dates back to discoveries in chickens at the beginning of the 20th century with evidence that a cell-free filtrate could transmit the propensity to grow cancers. Later, studies with similarly derived filtrates from mammalian tumors showed that hosts could develop immunity to subsequent exposures. Epidemiologic studies linked cervical cancer to members of a family of viruses that cause papillomatosis and common warts. This led to work with DNA hybridization demonstrating a causal relationship. The formation of virus-like particles from viral capsid proteins led to the development of models for safe and effective vaccines. While much work remains with the acceptance of universal vaccination, the HPV vaccines Gardasil and Cervarix thus represent a century of successful translational research.

Oncogenes and RNA splicing of human tumor viruses

Approximately 10.8% of human cancers are associated with infection by an oncogenic virus. These viruses include human papillomavirus (HPV), Epstein–Barr virus (EBV), Merkel cell polyomavirus (MCV), human T-cell leukemia virus 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), hepatitis C virus (HCV) and hepatitis B virus (HBV). These oncogenic viruses, with the exception of HCV, require the host RNA splicing machinery in order to exercise their oncogenic activities, a strategy that allows the viruses to efficiently export and stabilize viral RNA and to produce spliced RNA isoforms from a bicistronic or polycistronic RNA transcript for efficient protein translation. Infection with a tumor virus affects the expression of host genes, including host RNA splicing factors, which play a key role in regulating viral RNA splicing of oncogene transcripts. A current prospective focus is to explore how alternative RNA splicing and the expression of viral oncogenes take place in a cell- or tissue-specific manner in virus-induced human carcinogenesis.

Intraperitoneal oxidative stress in rabbits with papillomavirus-associated head and neck cancer induces tumoricidal immune response that is adoptively transferable

PURPOSE

How tumors evade or suppress immune surveillance is a key question in cancer research, and overcoming immune escape is a major goal for lengthening remission after cancer treatment. Here, we used the papillomavirus-associated rabbit auricular VX2 carcinoma, a model for studying human head and neck cancer, to reveal the mechanisms underlying the antitumorigenic effects of intraperitoneal oxidative stress following O3/O2-pneumoperitoneum (O3/O2-PP) treatment.

EXPERIMENTAL DESIGN

Solid auricular VX2 tumors were induced in immune-competent adult New Zealand White Rabbits. Animals were O3/O2-PP- or sham-treated, after which they underwent tumor ablation upon reaching no-go criteria. CD3(+) tumor-infiltrating lymphocytes (TIL) were evaluated by immunohistochemistry, and expression levels of 84 immune response genes were measured by quantitative real-time PCR. Adoptive transfer of peripheral blood leukocytes (PBL)-derived from animals with tumor regression-into control animals with progressing tumors was implemented to assess acquired tumor resistance functionally.

RESULTS

Auricular VX2 tumors regressing after O3/O2-PP treatment exhibited increased levels of CD3(+) TILs; they also exhibited enhanced expression of genes that encode receptors involved in pattern recognition, molecules that are required for antigen presentation and T cell activation, and inflammatory mediators. Adoptive cell transfer of PBLs from donor rabbits with regressing tumors to recipient rabbits with newly implanted VX2 carcinoma resulted in acquired tumor resistance of the host and tumor regression.

CONCLUSION

Intraperitoneal oxidative stress effectively converts the immune response against the papillomavirus-associated rabbit VX2 carcinoma from tumor permissive to tumoricidal and leads to a sustainable, adoptively transferable oncolytic immune response.

Joint infectious causation of human cancers

Joint infectious causation of cancer has been accepted in a few well-studied instances, including Burkitt's lymphoma and liver cancer. In general, evidence for the involvement of parasitic agents in oncogenesis has expanded, and recent advances in the application of molecular techniques have revealed specific mechanisms by which host cells are transformed. Many parasites evolve to circumvent immune-mediated detection and destruction and to control critical aspects of host cell reproduction and survival: cell proliferation, apoptosis, adhesion, and immortalization. The host has evolved tight regulation of these cellular processes-the control of each represents a barrier to cancer. These barriers need to be compromised for oncogenesis to occur. The abrogation of a barrier is therefore referred to as an essential cause of cancer. Alternatively, some aspects of cellular regulation restrain but do not block oncogenesis. Relaxation of a restraint is therefore referred to as an exacerbating cause of cancer. In this chapter, we explore past and current evidence for joint infectious causation of cancer in the context of essential and exacerbating causes. We stress that discovery of joint infectious causation may provide great improvements in controlling cancer, particularly through the identification of many additional nonhuman targets for synergistic interventions for prevention and treatment.

A novel papillomavirus in Adélie penguin (Pygoscelis adeliae) faeces sampled at the Cape Crozier colony, Antarctica

Papillomaviruses are epitheliotropic viruses that have circular dsDNA genomes encapsidated in non-enveloped virions. They have been found to infect a variety of mammals, reptiles and birds, but so far they have not been found in amphibians. Using a next-generation sequencing de novo assembly contig-informed recovery, we cloned and Sanger sequenced the complete genome of a novel papillomavirus from the faecal matter of Adélie penguins (Pygoscelis adeliae) nesting on Ross Island, Antarctica. The genome had all the usual features of a papillomavirus and an E9 ORF encoding a protein of unknown function that is found in all avian papillomaviruses to date. This novel papillomavirus genome shared ~60 % pairwise identity with the genomes of the other three known avian papillomaviruses: Fringilla coelebs papillomavirus 1 (FcPV1), Francolinus leucoscepus papillomavirus 1 (FlPV1) and Psittacus erithacus papillomavirus 1. Pairwise identity analysis and phylogenetic analysis of the major capsid protein gene clearly indicated that it represents a novel species, which we named Pygoscelis adeliae papillomavirus 1 (PaCV1). No evidence of recombination was detected in the genome of PaCV1, but we did detect a recombinant region (119 nt) in the E6 gene of FlPV1 with the recombinant region being derived from ancestral FcPV1-like sequences. Previously only paramyxoviruses, orthomyxoviruses and avian pox viruses have been genetically identified in penguins; however, the majority of penguin viral identifications have been based on serology or histology. This is the first report, to our knowledge, of a papillomavirus associated with a penguin species.

Review of the clinical and biologic aspects of human papillomavirus-positive squamous cell carcinomas of the head and neck

Human papillomavirus (HPV), a known etiology of a subset of head-and-neck squamous cell carcinomas (HNCs), causes numerous alterations in normal cellular functions. This article reviews the biology, detection, and treatment of HPV-positive HNC. The role of HPV oncoproteins in tumor development, the natural history of HPV infection, and risk factors for and prevention of transmission of oral HPV are considered. Commonly used methods for detecting HPV infection, including limitations of these methods, are discussed to aid the practicing clinician in using these tests in their clinical practice. Clinical characteristics of HPV-positive HNC, including potential explanations for the improved outcomes seen in patients with HPV-positive HNC, are assessed. Ongoing clinical trials specific for patients with HPV-positive HNC are described, and areas in need of additional research are summarized. Until the results of ongoing trials are known, treatment of HPV-positive HNC should not differ in clinical practice from treatment of similar non-HPV related cancers.

Human papillomavirus genomics: past, present and future

Human papillomaviruses (HPV) are a group of divergent DNA viruses, of which a select few evolutionarily related HPVs have emerged to be highly oncogenic and of significant medical importance. Essentially all cases of cervical cancer, as well as a subset of other anogenital and oral cancers are caused by this limited set of HPV types. At present, over 150 HPV types have been identified and may be classified into genera, species and types based upon comparison of the viral genome. Established nucleotide phylogenies sort the highly pathogenic HPV types to the genus Alphapapillomavirus (α-PV). A species group includes viral types with 60-70% genomic nucleotide similarity that share a most-recent common ancestor; for example the species group's alpha-9 (HPV16-related) and alpha-7 (HPV18-related), contain the majority of known oncogenic HPV types. Genomes from the same HPV type with 1-10% nucleotide differences designate HPV variant lineages. The established nucleotide variations observed in extant HPV genomes have been fixed through evolutionary processes prior to human population expansion and global dissemination. To characterize viral types and variants associated with pathology for clinical applications (e.g. screening), molecular epidemiological studies have proven essential for identifying links between HPV natural history and carcinogenicity. This chapter presents a historical account of HPV genomics in the context of major discoveries and advances over the past 2 thousand years.

Metabolomic Analysis of Liver Tissue from the VX2 Rabbit Model of Secondary Liver Tumors

Purpose. The incidence of liver neoplasms is rising in USA. The purpose of this study was to determine metabolic profiles of liver tissue during early cancer development. Methods. We used the rabbit VX2 model of liver tumors (LT) and a control group consisting of sham animals implanted with Gelfoam into their livers (LG). After two weeks from implantation, liver tissue from lobes with and without tumor was obtained from experimental animals (LT+/LT−) as well as liver tissue from controls (LG+/LG−). Peaks obtained by Gas Chromatography-Mass Spectrometry were subjected to identification. 56 metabolites were identified and their profiles compared between groups using principal component analysis (PCA) and a mixed-effect two-way ANOVA model. Results. Animals recovered from surgery uneventfully. Analyses identified a metabolite profile that significantly differs in experimental conditions after controlling the False Discovery Rate (FDR). 16 metabolites concentrations differed significantly when comparing samples from (LT+/LT−) to samples from (LG+/LG−) livers. A significant difference was also shown in 20 metabolites when comparing samples from (LT+) liver lobes to samples from (LT−) liver lobes. Conclusion. Normal liver tissue harboring malignancy had a distinct metabolic signature. The role of metabolic profiles on liver biopsies for the detection of early liver cancer remains to be determined.