Experiments on the cause of the rabbit carcinomas derived from virus-induced papillomas. II. Loss by the Vx2 carcinoma of the power to immunize hosts against the papilloma virus

Cottontail Rabbit Papillomavirus (CRPV) Related Animal Models for Head and Neck Cancer Research: A Comprehensive Review of the Literature

Having suitable animal models is crucial to mimic human disease states and for the successful transfer of experimental data into clinical practice. In the field of papillomavirus research, the domestic rabbit (Oryctolagus cuniculus) has served as an indispensable model organism for almost 100 years. The identification and characterization of the first papillomaviruses in rabbits, their carcinogenic potential and their immunogenicity have contributed significantly to the state of knowledge on the genetics and life cycle of papillomaviruses in general, as well as the development of antiviral strategies such as vaccination procedures. Due to the high species specificity of papillomaviruses, only rabbit papillomaviruses (RPVs) can be used for animal studies on papilloma-based tumor diseases in the rabbit. The major focus of this article is on cottontail rabbit papillomavirus (CRPV)-related rabbit squamous cell carcinoma (RSCC). A brief history outlines the discovery and generation of experimentally used RSCC tumors. A comprehensive overview of the current CRPV-associated VX2 carcinoma-based tumor models with a major focus on human head and neck squamous cell carcinoma (HNSCC) tumor models is provided, and their strengths in terms of transferability to human HNSCC are discussed.

Tertiary Lymphoid Structures (TLSs) and Stromal Blood Vessels Have Significant and Heterogeneous Impact on Recurrence, Lymphovascular and Perineural Invasion amongst Breast Cancer Molecular Subtypes

BACKGROUND

Tertiary lymphoid structures (TLSs) mediate local antitumor immunity, and interest in them significantly increased since cancer immunotherapy was implemented. We examined TLS- tumor stromal blood vessel interplay for each breast cancer (BC) molecular subtype related to recurrence, lymphovascular invasion (LVI), and perineural invasion (PnI).

METHODS

TLSs were quantified on hematoxylin and eosin stain specimens followed by CD34/smooth muscle actin (SMA) double immunostaining for stromal blood vessel maturation assessment. Statistical analysis linked microscopy to recurrence, LVI, and PnI.

RESULTS

TLS negative (TLS-) subgroups in each BC molecular subtype (except to Luminal A) have higher LVI, PnI, and recurrence. A significant rise in LVI and PnI were observed for the HER2+/TLS- subgroup (p < 0.001). The triple negative breast cancer (TNBC)/TLS- subgroup had the highest recurrence and invasion risk which was also significantly related to tumor grade. PnI but not LVI significantly influenced recurrence in the TNBC/TLS+ subgroup (p < 0.001). TLS-stromal blood vessel interrelation was different amongst BC molecular subtypes.

CONCLUSION

BC invasion and recurrence are strongly influenced by TLS presence and stromal blood vessels, especially for HER2 and TNBC BC molecular subtypes.

Mesenchymal Stem Cells Promote Tumor Progression via Inducing Stroma Remodeling on Rabbit VX2 Bladder Tumor Model

Background and aim: Mesenchymal stem cells (MSCs) are capable of impacting tumor progression but its role in tumor stroma remodeling still remains unclear. This present study was aimed to evaluate the potential function of MSCs on tumor stroma remodeling using rabbits VX2 bladder tumor model. Methods: The VX2 bladder tumor models were established by injecting mixed cell suspensions (10⁶ of VX2 tumor cells and 0/10⁶/10⁷ of autologous MSCs in group A, B, C, respectively) into the bladder mucosa using thirty male New Zealand white rabbits. The tumor volume was measured by ultrasound at the time points of 1st, 2nd, 3rd and 4th week after inoculation. At the end of the fourth week, the tumor tissue expressions of basic fibroblast growth factor (bFGF), transforming growth factor beta 1 (TGFβ-1), hepatocyte growth factor (HGF), matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9) were determined using Real-time quantitative PCR and immunohistochemistry. Masson trichrome staining and Cy3-FITC double-labelled immunofluorescence staining were used to determine the MSCs distribution in tumor tissue in another two rabbits implanted with a cell suspension of 10⁶ VX2 tumor cells and 10⁶ autologous MSCs. Results: MSCs were homogeneously distributed in tumor tissues after 7 days of inoculation, which were not consistent with the distribution of tumor stroma. After 21 days of inoculation, MSCs have been integrated into tumor interstitial tissue and mainly distributed in the mesenchyma around the tumor nest. At the 1st, 2nd, 3rd and 4th week time point, tumor volume in group A < group B < group C, and the difference has statistical significance (all p<0.001).The relative mRNA and protein levels of bFGF, TGFβ-1 and HGF were significantly higher in group B and C compared with group A (all p<0.05), as well as the mRNA levels of bFGF, HGF were higher in group C than group B (p<0.05), and the protein levels of bFGF, TGFβ-1 were higher in group C than group B (p<0.05). The mRNA and protein levels of MMP2 were significantly higher in group B, C than group A (p<0.05). MMP9 was increasingly over expressed along with the growing amount of MSCs inoculated within tumor, both at the level of mRNA and protein (all p<0.05). Conclusion: MSCs participate in tumor stroma remodeling via inducing overexpression of some important growth factors and MMPs.

Local Intratracheal Delivery of Perfluorocarbon Nanoparticles to Lung Cancer Demonstrated with Magnetic Resonance Multimodal Imaging

Eighty percent of lung cancers originate as subtle premalignant changes in the airway mucosal epithelial layer of bronchi and alveoli, which evolve and penetrate deeper into the parenchyma. Liquid-ventilation, with perfluorocarbons (PFC) was first demonstrated in rodents in 1966 then subsequently applied as lipid-encapsulated PFC emulsions to improve pulmonary function in neonatal infants suffering with respiratory distress syndrome in 1996. Subsequently, PFC nanoparticles (NP) were extensively studied as intravenous (IV) vascular-constrained nanotechnologies for diagnostic imaging and targeted drug delivery applications.

Methods: This proof-of-concept study compared intratumoral localization of fluorescent paramagnetic (M) PFC NP in the Vx2 rabbit model using proton (¹H) and fluorine (¹⁹F) magnetic resonance (MR) imaging (3T) following intratracheal (IT) or IV administration. MRI results were corroborated by fluorescence microscopy.

Results: Dynamic ¹H-MR and ¹⁹F-MR images (3T) obtained over 72 h demonstrated marked and progressive accumulation of M-PFC NP within primary lung Vx2 tumors during the first 12 h post IT administration. Marked ¹H and ¹⁹F MR signal persisted for over 72 h. In contradistinction, IV M-PFC NP produced a modest transient signal during the initial 2 h post-injection that was consistent circumferential blood pool tumor enhancement. Fluorescence microscopy of excised tumors corroborated the MR results and revealed enormous intratumor NP deposition on day 3 after IT but not IV treatment. Rhodamine-phospholipid incorporated into the PFC nanoparticle surfactant was distributed widely within the tumor on day 3, which is consistent with a hemifusion-based contact drug delivery mechanism previously reported. Fluorescence microscopy also revealed similar high concentrations of M-PFC NP given IT for metastatic Vx2 lung tumors. Biodistribution studies in mice revealed that M-PFC NP given IV distributed into the reticuloendothelial organs, whereas, the same dosage given IT was basically not detected beyond the lung itself. PFC NP given IT did not impact rabbit behavior or impair respiratory function. PFC NP effects on cells in culture were negligible and when given IV or IT no changes in rabbit hematology nor serum clinical chemistry parameters were measured.

Conclusion: IT delivery of PFC NP offered unique opportunity to locally deliver PFC NP in high concentrations into lung cancers with minimal extratumor systemic exposure.

Bone mesenchymal stem cells differentiate into myofibroblasts in the tumor microenvironment

The aim of the present study was to investigate the tropism of mesenchymal stem cells (MSCs) to the tumor microenvironment, and to evaluate the feasibility of bone marrow mesenchymal stem cells differentiating into myofibroblasts in vitro. A total of 1 ml bone marrow was extracted from the greater trochanter of one male New Zealand rabbit, and MSCs were obtained by density gradient centrifugation and cultured routinely. The surface markers were analyzed by flow cytometry. A VX2 tumor was aseptically excised from another male New Zealand rabbit and primary cultured. The tropism of MSCs for 30% and 50% VX2 conditioned medium was determined by using Transwell migration assays. MSCs were incubated in 30% VX2 conditioned medium for 7 or 14 days. The messenger (m)RNA levels and protein expression of α-smooth muscle actin (α-SMA) and vimentin were measured by reverse transcription-polymerase chain reaction and western blotting. MSCs were observed to have a spindle shape. The cultured MSCs were cluster of differentiation (CD)44⁺, CD105⁺, CD106⁺ and CD34^-. VX2 cells demonstrated a spindle or polygon shape. In the Transwell assay, it was observed that the migrated cells appeared more frequently in the 30% VX2 conditioned medium group compared with the other groups when microscopically examined, which was additionally confirmed by the results of a colorimetric assay. The mRNA levels and protein expression of α-SMA and vimentin significantly increased in the test group compared with the control group at 7 days (P<0.01), and further increased in the test group at 14 days (P<0.01). The results of the present study demonstrated that MSCs have tropism for the tumor microenvironment and furthermore, may differentiate into myofibroblasts in the tumor microenvironment in vitro. The present study suggested that MSCs may migrate to the tumor and subsequently differentiate into myofibroblasts due to the tumor microenvironment, which may lead to promotion of the growth of the tumor. The present study additionally suggested that MSCs may be the precursors of tumor/carcinoma-associated myofibroblasts.

Angiogenesis dependent characteristics of tumor observed on rabbit VX2 hepatic carcinoma

OBJECTIVE

To evaluate angiogenesis dependent characteristics of carcinoma proliferation, metastasis and to found if there is tumor vascularity architecture defect.

METHODS

36 rabbits were random divided into 2 groups: Experimental group: 18 rabbits liver were implanted with VX2 tumor by surgery operation;

CONTROL GROUP

18 experimental rabbits performed the same surgery operation without tumor implantation, the course of tumor growth and blood vessel invasion was observed by autopsy. One slide was used for hematoxylin-eosin (HE) staining, one slide was used for elastic fiber staining by Victoria blue and Ponceau's histochemical staining, and one slide was used for vascular endothelial cell immunohistochemical staining with biotinylated-ulex europaeus agglutinin I (UEA I); all three slides were observed under an optical microscopic. One additional slide was systematically observed by electron microscopy. SPSS 19.0 software was used for the statistical analyses of the data.

RESULTS

The tumor grew acceleration after tumor angiogenesis, volume of original tumors was correlated with vascular caliber. The central tumor found necrosis without enough blood supply while tumor grew rapidly after tumor angiogenesis. The tumor infiltrated into liver blood sinus, blood vessels in hepatic interstitial tissue, the liver capsular vein and important organs metastasis such as lungs, kidneys, abdominal cavity caused rabbits died. The average vascular density count of 18 experimental rabbits under 400 times light microscope were 43.17 ± 8.68/vessels/High Power Field; Tumor vascular diameter all within 200 μm. Vascular elastic fiber staining presented tumor blood vessels internal, external elastic plate intact, vascular endothelial cells organelles of tumor were integrity without endothelial cells architecture defect found by pathologic observation.

CONCLUSION

Proliferation and metastasis of rabbit VX2 hepatic carcinoma was correlated with tumor angiogenesis and no tumor vascular architecture defect was found by pathologic observation, it need further exploration by other methods.

Automated Quantification of Tumor Viability in a Rabbit Liver Tumor Model after Chemoembolization Using Infrared Imaging

The rabbit VX2 tumor is a fast-growing carcinoma model commonly used to study new therapeutic devices, such as catheter-based therapies for patients with inoperable hepatocellular carcinoma. The evaluation of tumor viability after such locoregional therapies is essential to directing hepatocellular carcinoma management. We used infrared microspectroscopy for the automatic characterization and quantification of the VX2 liver tumor viability after drug-eluting beads transarterial chemoembolization (DEB-TACE). The protocol consisted of K-means clustering followed by principal component analysis (PCA) and linear discriminant analysis (LDA). The K-means clustering was used to classify the spectra from the infrared images of control or treated tumors and to build a database of many tissue spectra. On the basis of this reference library, the PCA-LDA analysis was used to build a predictive model to identify and quantify automatically tumor viability on unknown tissue sections. For the DEB group, the LDA model determined that the surface of tumor necrosis represented 91.6% ± 8.9% (control group: 33.1% ± 19.6%; Mann-Whitney P = 0.0004) and the viable tumor 2.6% ± 4% (control group: 62.2% ± 15.2%; Mann-Whitney P = 0.0004). Tissue quantification measurements correlated well with tumor necrosis (r = 0.827, P < 0.0001) and viable tumor (r = 0.840, P < 0.0001). Infrared imaging and PCA-LDA analysis could be helpful for easily assessing tumor viability.

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.

Establishment of successively transplantable rabbit VX2 cancer cells that express enhanced green fluorescent protein

Morphological detection of cancer cells in the rabbit VX2 allograft transplantation model is often difficult in a certain region such as serosal cavity where reactive mesothelial cells mimic cancer cells and both cells share common markers such as cytokeratins. Therefore, tagging VX2 cells with a specific and sensitive marker that easily distinguishes them from other cells would be advantageous. Thus, we tried to establish a successively transplantable, enhanced green fluorescent protein (EGFP)-expressing VX2 model. Cancer cells obtained from a conventional VX2-bearing rabbit were cultured in vitro and transfected with an EGFP-encoding vector, and then successively transplanted in Healthy Japanese White rabbits (HJWRs) (n = 8). Besides, conventional VX2 cells were transplanted in other HJWRs (n = 8). Clinicopathological comparison analyses were performed between the two groups. The success rate of transplantation was 100% for both groups. The sensitivity and specificity of EGFP for immunohistochemical detection of VX2 cells were 84.3 and 100%, respectively. No significant differences in cancer cell morphology, tumor size (P = 0.742), Ki-67 labeling index (P = 0.878), or survival rate (P = 0.592) were observed between the two. VX2 cells can be genetically altered, visualized by EGFP, and successively transplanted without significant alteration of morphological and biological properties compared to those of the conventional model.

Molecular MR imaging of neovascular progression in the Vx2 tumor with αvβ3-targeted paramagnetic nanoparticles

PURPOSE

To assess the dependence of neovascular molecular magnetic resonance (MR) imaging on relaxivity (r1) of αvβ3-targeted paramagnetic perfluorocarbon (PFC) nanoparticles and to delineate the temporal-spatial consistency of angiogenesis assessments for individual animals.

MATERIALS AND METHODS

Animal protocols were approved by the Washington University Animal Studies Committee. Proton longitudinal and transverse relaxation rates of αvβ3-targeted and nontargeted PFC nanoparticles incorporating gadolinium diethylenetrianime pentaacedic acid (Gd-DTPA) bisoleate (BOA) or gadolinium tetraazacyclododecane tetraacetic acid (Gd-DOTA) phosphatidylethanolamine (PE) into the surfactant were measured at 3.0 T. These paramagnetic nanoparticles were compared in 30 New Zealand White rabbits (four to six rabbits per group) 14 days after implantation of a Vx2 tumor. Subsequently, serial MR (3.0 T) neovascular maps were developed 8, 14, and 16 days after tumor implantation by using αvβ3-targeted Gd-DOTA-PE nanoparticles (n = 4) or nontargeted Gd-DOTA-PE nanoparticles (n = 4). Data were analyzed with analysis of variance and nonparametric statistics.

RESULTS

At 3.0 T, Gd-DTPA-BOA nanoparticles had an ionic r1 of 10.3 L · mmol(-1) · sec(-1) and a particulate r1 of 927000 L · mmol(-1) · sec(-1). Gd-DOTA-PE nanoparticles had an ionic r1 of 13.3 L · mmol(-1) · sec(-1) and a particulate r1 of 1 197000 L · mmol(-1) · sec(-1). Neovascular contrast enhancement in Vx2 tumors (at 14 days) was 5.4% ± 1.06 of the surface volume with αvβ3-targeted Gd-DOTA-PE nanoparticles and 3.0% ± 0.3 with αvβ3-targeted Gd-DTPA-BOA nanoparticles (P = .03). MR neovascular contrast maps of tumors 8, 14, and 16 days after implantation revealed temporally consistent and progressive surface enhancement (1.0% ± 0.3, 4.5% ± 0.9, and 9.3% ± 1.4, respectively; P = .0008), with similar time-dependent changes observed among individual animals.

CONCLUSION

Temporal-spatial patterns of angiogenesis for individual animals were followed to monitor longitudinal tumor progression. Neovasculature enhancement was dependent on the relaxivity of the targeted agent.

Hepatic arterial administration of ginsenoside Rg3 and transcatheter arterial embolization for the treatment of VX2 liver carcinomas

Ginsenoside Rg3 has been demonstrated to inhibit tumor cell proliferation and angiogenesis. However, its effect on liver tumors when administered via the hepatic artery has not been investigated. The purpose of this study was to evaluate the therapeutic effect of hepatic artery administration of Rg3 combined with transcatheter arterial embolization (TAE) in the treatment of liver tumors. A total of 48 rabbits with VX2 liver tumors were randomly divided into four groups: Group 1, Rg3; Group 2, TAE; Group 3, Rg3 and TAE; and Group 4, control. Abdominal contrast computed tomography (CT) scans were performed 2 weeks before and after intervention to assess tumor growth. Immunohistochemical staining was used to detect the expression of the angiogenesis biomarkers CD31 and VEGF, and the cell apoptosis marker caspase-3. Semi-quantitative RT-PCR and western blotting were employed to detect the expression of the caspase-3, Bax and Bcl-2 apoptosis-related genes and proteins. In addition, HepG2 cells were treated with Rg3 at different concentrations (0, 25, 50, 75 and 100 mg/l) in vitro. An MTT assay and western blot analysis were used to analyze the cell proliferation and VEGF expression. Compared with the other experimental groups, the Rg3 and TAE group expressed significantly lower levels of CD31 and VEGF (P<0.05), significantly increased levels of the pro-apoptotic genes caspase-3 and Bax (P<0.05), and significantly reduced levels of anti-apoptotic Bcl-2 at the mRNA and protein levels (P<0.05). In vitro, Rg3 inhibited HepG2 cell proliferation and downregulated VEGF expression significantly. These results indicated that ginsenoside Rg3 combined with TAE may effectively inhibit tumor growth by inhibiting tumor angiogenesis and inducing cancer cell apoptosis.

100 years of Rous sarcoma virus

The discovery of Rous sarcoma virus, which was reported by Peyton Rous in the Journal of Experimental Medicine 100 years ago, opened the field of tumor virology. It showed that some cancers have infectious etiology, led to the discovery of oncogenes, and laid the foundation for the molecular mechanisms of carcinogenesis. Rous spent his entire research career at The Rockefeller Institute, and he was the JEM's longest serving editor. Here, we comment briefly on the life of this remarkable scientist and on the importance of his discoveries.

The dynamics of glutathione species and ophthalmate concentrations in plasma from the VX2 rabbit model of secondary liver tumors

Purpose. Available tumor markers have low sensitivity/specificity for the diagnosis of liver tumors. The present study was designed to evaluate the oxidoreductive status of the liver as surrogates of tumor subsistence and growth. Methods. Glutathione species (GSH:GSSG), ophthalmate (OA) concentrations, and their turnover were measured in plasma of rabbits (n = 6) in their healthy state and in the state of tumor growth after implantation of the VX2 carcinoma in their liver. Tumors were allowed to grow for a period of 14 days when rabbits were sacrificed. Livers were removed and cysteine concentration was measured in liver tissue. Results. Tumor growth was found in 100% of the rabbits. Concentration and labeling of GSH/GSSG were similar in experimental animals before and after tumor implantation and to sham animals. In contrast, OA concentration increased significantly in experimental animals after tumor implantation when compared to same animals prior to tumor implantation and to sham animals (P < .05). The concentration of cysteine, a precursor of GSH, was found to be significantly lower in the liver tissue adjacent to the tumor (P < .05). Conclusion. Disturbances in the oxidoreductive state of livers appear to be a surrogate of early tumor growth.

Targeting of VX2 rabbit liver tumor by selective delivery of 3-bromopyruvate: a biodistribution and survival study

The aim of this study was to determine the biodistribution and tumor targeting ability of (14)C-labeled 3-bromopyruvate ([(14)C]3-BrPA) after i.a. and i.v. delivery in the VX2 rabbit model. In addition, we evaluated the effects of [(14)C]3-BrPA on tumor and healthy tissue glucose metabolism by determining (18)F-deoxyglucose (FDG) uptake. Last, we determined the survival benefit of i.a. administered 3-BrPA. In total, 60 rabbits with VX2 liver tumor received either 1.75 mM [(14)C]3-BrPA i.a., 1.75 mM [(14)C]3-BrPA i.v., 20 mM [(14)C]3-BrPA i.v., or 25 ml of phosphate-buffered saline (PBS). All rabbits (with the exception of the 20 mM i.v. group) received FDG 1 h before sacrifice. Next, we compared survival of animals treated with i.a. administered 1.75 mM [(14)C]3-BrPA in 25 ml of PBS (n = 22) with controls (n = 10). After i.a. infusion, tumor uptake of [(14)C]3-BrPA was 1.8 +/- 0.2% percentage of injected dose per gram of tissue (%ID/g), whereas other tissues showed minimal uptake. After i.v. infusion (1.75 mM), tumor uptake of [(14)C]3-BrPA was 0.03 +/- 0.01% ID/g. After i.a. administration of [(14)C]3-BrPA, tumor uptake of FDG was 26 times lower than in controls. After i.v. administration of [(14)C]3-BrPA, there was no significant difference in tumor FDG uptake. Survival analysis showed that rabbits treated with 1.75 mM 3-BrPA survived longer (55 days) than controls (18.6 days). Intra-arterially delivered 3-BrPA has a favorable biodistribution profile, combining a high tumor uptake resulting in blockage of FDG uptake with no effects on healthy tissue. The local control of the liver tumor by 3-BrPA resulted in a significant survival benefit.

Development of a rabbit pleural cancer model by using VX2 tumors

Primary and secondary pleural cancer remains an important clinical problem, with research progress limited by the lack of a suitable moderate- to large-sized (3 to 4 kg) animal model of pleural cancer. Many potential pleura-based imaging and treatment modalities cannot be investigated sufficiently by using currently available small murine animal models because their pleural space is not comparable to that of humans and therefore does not allow for the use of standard thoracoscopic techniques. Here we describe the development of a reproducible model of pleural malignancy in moderate-sized immunocompetent rabbits. Under thoracoscopic guidance, 9-15 x 10(6) VX2 carcinoma cells were inoculated into the plural space of 3 to 4 kg New Zealand white rabbits that had undergone gentle pleural abrasion. Malignant tumor involvement developed on the visceral and parietal pleural surfaces in an average of 2 to 4 wk. This novel pleural tumor model induction method likely will facilitate a broad range of investigations of pleural cancer diagnostics and therapeutics.

Cutaneous papillomatosis and carcinomatosis in the Western barred bandicoot (Perameles bougainville)

A progressive wart-like syndrome in both captive and wild populations of the Western barred bandicoot (WBB) is hindering conservation efforts to prevent the extinction of this endangered marsupial. In this study, 42 WBBs exhibiting the papillomatosis and carcinomatosis syndrome were examined. The disease was characterized by multicentric proliferative lesions involving cutaneous and mucosal surfaces, which were seen clinically to increase in size with time. Grossly and histologically the smaller skin lesions resembled papillomas, whereas the larger lesions were most commonly observed to be squamous cell carcinomas. Large amphophilic intranuclear inclusion bodies were observed in hyperplastic conjunctival lesions of 8 WBBs under light microscopy. Conjunctival lesions from 2 WBBs examined using transmission electron microscopy contained a crystalline array of spherical electron-dense particles of 45-nm diameter, within the nucleus of conjunctival epithelial cells, consistent with a papillomavirus or polyomavirus. Conjunctival samples from 3 bandicoots that contained intranuclear inclusion bodies also demonstrated a positive immunohistochemical reaction after indirect immunohistochemistry for papillomavirus structural antigens. Ultrastructural and/or immunohistochemical evidence of an etiologic agent was not identified in the nonconjunctival lesions examined. Here we describe the gross, histopathologic, ultrastructural, and immunohistochemical findings of a papillomatosis and carcinomatosis syndrome recently identified in the WBB.

Volociximab, a chimeric integrin alpha5beta1 antibody, inhibits the growth of VX2 tumors in rabbits

Angiogenesis, the process by which new blood vessels form from existing vasculature, is critical for tumor growth and invasion. Growth factors, such as VEGF, initiate signaling cascades resulting in the proliferation of resting endothelial cells. Blockade of growth factor pathways has proven effective in inhibiting angiogenesis and tumor growth in vivo. Integrins, including the integrin alpha5beta1, are also important mediators of angiogenesis and these adhesion molecules also regulate cancer cell growth and migration in vitro. Volociximab is a high affinity, function-blocking antibody against integrin alpha5beta1 that is currently in multiple Phase II oncology clinical trials. Volociximab displays potent anti-angiogenic activity in a monkey model of choroidal neovascularization. In this study, we explored the consequences of integrin alpha5beta1 blockade on tumorigenesis. Because volociximab does not cross-react with rodent alpha5beta1, the syngeneic rabbit VX2 carcinoma model was utilized as an alternative to standard mouse xenograft models for the assessment of anti-tumor activity of volociximab. Volociximab administered intravenously to rabbits bearing VX2 tumors is detectable on tumor cells and vasculature 45 min post-administration. Volociximab was found to significantly inhibit the growth of tumors growing subcutaneously or intramuscularly, despite a 20-fold lower affinity for rabbit integrin, relative to human. This effect was found to correlate with decreased blood vessel density within these tumors. These results support the use of volociximab in the intervention of malignant disease.

Effect of transcatheter arterial embolization on levels of hypoxia-inducible factor-1alpha in rabbit VX2 liver tumors

PURPOSE

To test the hypothesis that transcatheter arterial embolization (TAE) of VX2 rabbit liver tumors increases the expression of hypoxia-inducible factor-1alpha (HIF-1alpha), a transcription factor that regulates the expression of pro-angiogenic genes.

MATERIALS AND METHODS

VX2 tumors were implanted in the livers of eight New Zealand white rabbits. Once tumor growth was seen at T2-weighted turbo spin-echo magnetic resonance (MR) imaging, four of the eight rabbits underwent TAE with 45-150-mum polyvinyl alcohol particles. The remaining four rabbits served as non-TAE controls. The TAE end point was stasis of antegrade blood flow. All rabbits were sacrificed for tumor harvest 2 hours after TAE. Tumor tissue and corresponding normal liver tissue in each rabbit liver were stained with anti-human HIF-1alpha monoclonal antibody and reviewed with light microscopy. Percentages of stained viable tumor and normal liver cells were compared by using the Mann-Whitney U test (alpha=0.05).

RESULTS

In eight rabbits with 24 discrete liver tumors, the mean percentage (+/-standard deviation) of positive HIF-1alpha-stained cells in the TAE group was greater than that in the control group (19%+/-7.0 vs 12%+/-8.0, respectively) (P=.05). Normal liver tissue in both the TAE and control groups showed no HIF-1alpha staining.

CONCLUSION

Although HIF-1alpha is not expressed in normal rabbit liver parenchyma-even after TAE-HIF-1alpha expression is present in implanted VX2 rabbit liver tumors and significantly increased in lesions that have undergone embolization.

Relationships among tumor burden, tumor size, and the changing concentrations of fibrin degradation products and fibrinolytic factors in the pleural effusions of rabbits with VX2 lung tumors

The VX2 tumor is derived from a papilloma virus-induced rabbit epithelial cell line. If VX2 tumor cells (trapped in a plasma clot) are introduced intravenously into NZW rabbits, the cells lodge in the lung capillary bed and produce tumors. Independently of the tumor burden (ie, the total tumor weight per rabbit), approximately 15% of rabbits with VX2 lung tumors accumulate an effusion in the interpleural space and this pleural effusion contains products of hemostasis. We hypothesized that these products were of intra-tumoral origin and that they changed in concentration as tumor burden increased. Interrelationships among lung-, tumor-weights, and pleural effusion volumes, and the concentrations of fibrinolytic factors, their catabolic products, and other proteins of pleural effusions were measured in rabbits with a wide range of tumor burdens. Positive correlations between tumor burden and total lung weight and between pleural effusion volume and net lung weight suggested that interstitial fluid from the stroma of tumors passed directly into the extravascular space of the lung(s) and into the interpleural space(s). Analyses of pleural effusions indicated that plasminogen-, alpha(2)-antiplasmin-, and plasminogen activator inhibitor-1-related proteins, urokinase-like- and tissue-plasminogen activator activities, and vascular endothelial growth factor increased in concentration up to a tumor burden of approximately 20-25 g. Plasmin activity and intact fibrinogen were absent. The concentration of fibrin(ogen) degradation products did not change significantly up to a tumor burden of approximately 25 g but increased substantially as tumor burdens exceeded 25 g. In conclusion, interstitial fluid from tumors enters the extravascular space of the host and may accumulate with fluid from non-tumor sources as a pleural effusion. The concentrations of fibrinolytic factors and their products in pleural effusions reflect the tumor burden of the rabbit. Conceivably, the components of a malignant effusion contain much information about the extent of tumor growth.

Fibrinogen catabolism within the procoagulant VX-2 tumor of rabbit lung in vivo: Effluxing fibrin(ogen) fragments contain antiangiogenic activity

Many types of solid tumors are known to be procoagulant environments. This is partly because a hyperpermeable vascular system within the tumor allows plasma hemostatic factors to accumulate in relatively high concentrations in the stroma, and many solid-tumor cells express tissue factor or a procoagulant factor. These circumstances appear to exist in the VX-2 lung tumor of the New Zealand White (NZW) rabbit, and they sustain a measurable turnover of stromal deposits of fibrin(ogen). We have measured the turnover of fibrinogen within tumors of the VX-2 tumor-burdened rabbit and analysed the catabolic products of fibrin(ogen) and the status of fibrinolysis in tumor-derived interpleural effusate. Using intravenously injected (125)I-labeled rabbit fibrinogen as a marker, we found that fibrinogen (approximate blood concentration 1740 microg/mL) passed from blood to VX-2 tumor stroma, saturating the tumor at a concentration of approximately 348 microg fibrinogen/g in approximately 12 hours. We measured fibrin(ogen) fragments, at a concentration of approximately 292 microg/mL, in interpleural effusates that we recovered from 13% of the VX-2-burdened rabbits. Unreduced fibrin(ogen) fragments consisted of 4 major components with a relative molecular mass of approximately 250,000 (assumed to be fragment X; approximately 9% of total fragments from densitometry of immunoblots), 200,000 (d-dimer; 41%), 110,000 (fragment D; 49%), and 50,000 to 55,000 (fragment E; 1%-2%) kD. Total fibrin(ogen) fragments immunopurified from effusates exhibited an antiangiogenic effect when subjected to a chick embryo chorioallantoic membrane procedure. Interpleural effusates were devoid of plasmin activity or active plasminogen activator inhibitor-1 but contained plasmin complexes and active urokinase-like plasminogen activator (uPA), alpha(2)-antiplasmin, and thrombin-activatable fibrinolysis inhibitor. We speculate that VX-2 cells release uPA to activate fibrinolysis within the tumor stroma. Catabolic products of hemostasis (eg, fibrinolytic fragments, angiostatin) flux from the stroma into the interpleural space, thereby providing a net antiangiogenic property to the effusate and ultimately to the lymphatic and circulatory systems.

Experimental microcomputed tomography study of the 3D microangioarchitecture of tumors

Differences between soft X-ray imaging and microcomputed tomography (micro-CT) in the microangiographic depiction of small vessels in tumors were compared to evaluate the tumors' 3D microangioarchitecture and the progress of growth-related neovascularization. VX2 carcinomas transplanted to the auricles of 24 rabbits randomly assigned to three groups were examined after 1, 3, and 7 days. Eight rabbits without transplants were the controls. Barium sulfate was injected into the auricular artery, and conventional soft X-ray images and micro-CT microangiograms of auricle specimens were studied. Micro-CT detected vessels with diameters of less than 50 microm, and imaging from several angles clearly showed the network of tumor vessels. Moreover, micro-CT confirmed the 3D process of growth-related neovascularization. There were no significant differences between the present findings and those of our previously published microscopic study. Micro-CT should prove useful for evaluating the 3D microarchitecture of tumors and for clear imaging of tumor angiogenesis.

Evaluation of the microangioarchitecture of tumors by use of monochromatic x-rays

RATIONALE AND OBJECTIVES

The purpose was to compare differences in the depiction of small vessels in tumors seen on microangiograms from a conventional soft x-ray system with those from a synchrotron radiation system and to evaluate the microangioarchitecture of these tumors and the growth of neovascularization.

METHODS

VX2 carcinomas transplanted to the auricles of 15 rabbits randomized into three groups were investigated after 1, 3, and 7 days. Five normal rabbits were the controls. Barium sulfate, to which sufficient gelatin had been added, was injected into the auricular artery. Microangiograms of auricle specimens were obtained with both a conventional soft x-ray system and a synchrotron radiation system.

RESULTS

The conventional x-ray system could detect vessels with diameters of approximately 100 microm, whereas the monochromatic synchrotron radiation system could detect small vessels with diameters of less than 25 microm. On day 1, there was moderate vascularization and flexure vessels were present in the transplantation area. On day 3, dilated vessels were present in the peripheral areas of the tumors and tortuous vessels in the central areas. On day 7, hypovascular areas had increased in the central area.

CONCLUSIONS

The synchrotron radiation system confirmed the growth of neovascularization in the tumors. This system should provide a useful tool for evaluating the microangioarchitecture of tumors.

Glucose catabolism in the rabbit VX2 tumor model for liver cancer: characterization and targeting hexokinase

The rabbit VX2 tumor when implanted in the liver has proven convenient as a model for studying hepatocellular carcinomas. However, its metabolic properties have not been well studied. Significantly, studies described here show that the VX2 tumor exhibits a high glycolytic/high hexokinase phenotype that is retained following implantation and growth in rabbit liver. In addition, results of a limited screen show that the glycolytic rate is inhibited best by 2-deoxyglucose (2DOG) and 3-bromopyruvate (3BrPA), the former compound of which is phosphorylated by hexokinase but not further metabolized, while the latter directly inhibits hexokinase. Finally, when tested on hepatoma cells in culture both inhibitors facilitated cell death. These studies underscore the usefulness of the VX2 tumor model for the study of advanced liver cancer and for selecting anti-hepatoma agents.

Tumor-enhancement effect of a Mn3+ metalloporphyrin derivative (ATN-4T) in magnetic resonance imaging

Magnetic resonance imaging is routinely used for tumor recognition in cancer diagnosis. The tumor image-enhancing characteristics of ATN-4T (THF-Mn-Asp), a Mn3+ metalloporphyrin derivative, were evaluated in rabbits. ATN-4T (10 mM) was diluted in gelatin to final concentrations ranging from 100 to 1 microM. Increasing concentrations of ATN-4T resulted in higher signal intensities. VX2 (squamous cell carcinoma) tumor-bearing rabbits were injected with 50 micromol/kg ATN-4T intravenously and T1 -weighted images were recorded continuously. Tumor images were compared with images of surrounding muscle tissue. T1-weighted images from ATN-4T-treated rabbits showed a marked enhancement of tumor contrast from 30 to 240 min postinjection. Microscopic examination revealed that carcinoma cells were scattered throughout the high contrast area of the tumor and were not seen in the surrounding muscles. ATN-4T appears useful for enhancing the intensity of tumors imaged by magnetic resonance.

Changes in nerve fibers adjacent to transplanted VX2 carcinoma in rabbit tongue

This study was undertaken to examine the relationship between malignant tumor tissue and nerve fibers using a transplantation model and nerve fiber strains. Most of the neural tissue, as well as the other host tissues, showed severe degenerative changes as the transplanted tumor grew. Furthermore, the degenerative changes were chiefly confined to the area anterior to the tumor. These changes were probably provoked chiefly by the compressive effects of the rapidly enlarging transplant. The results could possibly explain clinical symptoms such as paralysis or disturbances in the movement of the tongue observed occasionally in some patients with lingual carcinomas.

Localized hyperthermic treatment of experimental bone tumors with ferromagnetic ceramics

Localized hyperthermic treatment was carried out with use of a metastatic bone tumor model in rabbits. The experimental bone tumor was created by transplantation of pieces of tumor line VX2 into the medullary canal of rabbit tibiae. Two weeks after the transplantation, a ferromagnetic ceramic pin was inserted in the medullary canal. Then, hyperthermia (HT) of the tumor was accomplished with use of an alternating magnetic field for 50 min. All the rabbits were killed 5 weeks after tumor transplantation, and the therapeutic effect was evaluated histologically and roentgenographically. Almost all the tumor cells within the bone marrow were killed by this procedure. The area of tumor necrosis in the HT group was significantly larger than in the control group. The pathological fracture rate and displacement rate were reduced significantly by this treatment (38.5 and 0%) compared with the controls (92.3 and 92.3%). Therefore, HT with the use of ferromagnetic ceramics was effective for local control of malignant bone tumors and seems to be a promising new method of treatment.

Suppressive effect of doxorubicin on liver recurrence after resection of colonic VX2 cancer lesions: difference in efficacy according to the injection protocol

An animal model with liver cancer recurrence was induced by resecting colonic VX2 cancer lesions in 57 rabbits, and the effects of doxorubicin (ADR) on the recurrence were examined. Animals were divided into a control group and three chemotherapeutic groups: a portal injection group, to which ADR was injected into the portal vein after resection of the primary lesions; a peripheral injection group, to which ADR was injected into a peripheral vein after resection; and a preoperative injection group, to which an ADR dose of 0.5 mg/kg was peripherally injected 0, 1, and 2 days prior to resection followed by a portal injection of ADR 0.5 mg/kg after resection. The rate of liver recurrence was 100% in the control group, whereas it was 0% and 60% in the portal ADR 1.0 and 0.5 mg/kg injection groups, and 60% and 100% in the peripheral ADR 1.0 and 0.5 mg/kg injection groups. In the preoperative group, the rate was 0%, 100%, and 67% in the animals injected 2, 1, and 0 days prior to resection, respectively. These results suggest that portal injection or appropriate combinations of preoperative peripheral and portal injections of ADR are more effective than peripheral or portal injection alone in the suppression of liver recurrence.

Liver metastases induced by implantation of VX2 cancer into the gastrointestine

An experimental model with a high frequency of spontaneous liver metastases was induced by implantation of VX2 cancer cells into the gastrointestinal walls of 36 rabbits, and the developmental process of primary cancer lesions and metastases was examined histologically. Gastric and colonic cancer lesions showed similar growth patterns in both primary and metastatic lesions: the average diameter of primary lesions enlarged from 0.7-0.8 cm on Day 7 to 2.4-2.8 cm on Day 28. The frequency and average diameter of liver metastases were 25% and microscopically certificated levels on Day 14, 25% and 3 mm on Day 21, and 50% and 8 mm on Day 28 in the gastric wall-implantation group. They were, respectively, 20% and microscopically recognized levels on Day 14, 40% and 2 mm on Day 21, and 80% and 9 mm on Day 28 in the colonic wall-implantation group. Thus, the frequency and diameter of the metastases increased in parallel with the primary cancer growth. Liver metastases occurred only in animals with vascular invasion in primary lesions, though none of the animals with the invasion always showed the metastases. These results suggest that vascular invasion of cancer cells in the primary lesions may be a premise of liver metastases, and that this experimental model may be utilized as a useful tool for studying many aspects of the pathogenesis and/or therapy of the spontaneous liver metastases in gastrointestinal cancer.

Studies on heat treatment for immediate reimplantation of resected bone

Extracorporeal heat treatment for devitalizing the tumour-infiltrated bone segment without destroying its regenerative potential was investigated for the purpose of immediate reimplantation of the resected bone. Effects of heat treatment on cell viability and bone inductive properties were studied in cultured tumour cells and animal models. Heat treatment at 65 degrees C for 30 to 120 minutes resulted in complete devitalization of cells, preserving osteogenetic properties of the allogenic bone implant in the rabbit. The results of the experiments indicate that this procedure has advantages in devitalizing the resected bone for its immediate reimplantation and justify clinical application. The clinical application of this heat treatment in 3 cases is presented.

Study of the E2 gene product of the cottontail rabbit papillomavirus reveals a common mechanism of transactivation among papillomaviruses

The long control region (LCR) of the cottontail rabbit papillomavirus (CRPV) harbors a transcriptional promoter which can be transactivated, as reflected by cat gene expression, by cotransfection with plasmids which express the intact E2 open reading frame of CRPV, human papillomavirus type 18 (HPV18), and bovine papillomavirus type 1 (BPV1). The E2 protein of CRPV can also transactivate the LCRs of BPV1, HPV1, and HPV18 inserted in front of the cat gene in enhancer or promoter configuration. Competition experiments in vivo and binding studies with CRPV E2 protein synthesized in vitro suggest that the different E2 proteins transactivate transcription by a common mechanism involving binding to the same ACCG-CGGT target sequence. The C-terminal part of the protein is necessary for its DNA-binding function. Analysis of the transactivation data and of the LCR sequences of these four viruses suggests that the two cutaneous viruses (CRPV and BPV1) present a similar pattern of promoter regulation but that the activity of the promoters of genital human viruses is less dependent on E2 regulation and is at least partially regulated by cellular factors.

Two Shope papillomavirus-associated VX2 carcinoma cell lines with different levels of keratinocyte differentiation and transplantability

Two cell lines, named VX2T and VX2R, were isolated from the transplantable VX2 carcinoma, a wholly anaplastic tumor established from a carcinoma induced by the Shope cottontail rabbit papillomavirus (CRPV) (J.G. Kidd and P. Rous, J. Exp. Med. 71:813-838, 1940). The CRPV genome was found to be maintained and transcribed in both cell lines, as in the VX2 carcinoma. The VX2T cells retained the tumor-producing capacity in the rabbit and the low expression of epidermal keratinocyte differentiation of the VX2 tumor cells. The VX2R cells, although tumorigenic for nude mice, were no longer serially transplantable in the rabbit and expressed differentiated functions of keratinocytes. These data indicate that the anaplastic characteristic and the transplantability of VX2 carcinoma cells to immune competent allogenic hosts may be lost without any detectable modification of the physical state and transcription of the CRPV genome.

Cottontail rabbit papillomavirus-specific transcripts in transplantable tumors with integrated DNA

The viral DNA and viral transcripts of a VX2 and a VX7 transplantable carcinoma lines were analyzed. Both tumor lines contain equivalent numbers of gene copies per cell of exclusively integrated viral DNA. Integration is in head-to-tail tandem repeats, in probably three sites and at least two integration sites are common. In both tumors, about half of the viral genomes share a 90-bp deletion. Common integration sites and deletions suggest that the two tumor lines were derived from the same parent tumor. The tumors contain the same major viral transcripts of 1.3 and 2.0 kb also found in both papillomas and primary carcinomas of domestic rabbits [M. Nasseri, F. O. Wettstein, and J. G. Stevens, J. Virol. 44, 263-268 (1982)]. However, the carcinoma lines differ in their minor transcripts. VX7 has four minor transcripts of 5.2, 3.8, 3.6, and 3.0 kb and VX2 has two of 4.8 and 3.0 kb. The 4.8-kb transcript is relatively major and appears to be identical to a major transcript present in virus-producing tumors of cottontail rabbits [M. Nasseri and F. O. Wettstein, J. Virol. 51, 706-712 (1984)].

Physical state and transcription of the cottontail rabbit papillomavirus genome in warts and transplantable VX2 and VX7 carcinomas of domestic rabbits

The physical state and the transcription of the genome of cottontail rabbit papillomavirus (CRPV) in non-virus-producing warts and in the VX2 and VX7 transplantable carcinomas of domestic rabbits were compared. The CRPV DNA present in VX2 and VX7 carcinomas (10 to 20 and 100 to 200 genome equivalents per diploid cell, respectively) was found to be entirely integrated into the cellular DNA, most probably as head-to-tail tandem repeats, in contrast to warts, in which viral DNA (10 to 100 copies per diploid cell) was found only as free, mainly monomeric, molecules. In the VX7 tumor, ca. 50% of the viral DNA molecules were found to be longer than one genome length, indicating that viral DNA rearrangements had occurred. A major viral transcript of 1,250 bases was detected in warts and in VX2 and VX7 carcinomas. Complementary sequences were localized within the E region, the putative transforming region inferred from the nucleotide sequence of the CRPV genome (I. Giri, O. Danos, and M. Yaniv, manuscript in preparation). Analysis of heteroduplexes formed between single-stranded CRPV DNA and polyadenylated RNAs from the VX2 tumor showed that the 1,250-base RNA resulted from the splicing of the sequences corresponding to the open reading frame E6 to those corresponding to the 3' third of E2. A second viral transcript, measuring 2,000 bases, was detected in warts and, in lesser amounts than the 1,250-base species, in VX2 carcinoma, and a 2,100-base RNA was found in VX7 carcinoma. Complementary sequences to these messengers were localized to the same part of the genome as the 1,250-base species and to a contiguous fragment situated upstream. Heteroduplex analysis showed that the 2,000-base species from VX2 carcinoma resulted from the splicing of the sequences corresponding to E6 and E7 to those corresponding to the 3' third of E2. The sequences spliced out upon the maturation of the two messengers of VX2 carcinoma correspond to E1, the two-thirds of E2, and most of E4. Additional transcripts were found in VX7 carcinoma, a major 3,100-base species transcribed from the E region, and several minor species, measuring from 2,400 bases, which all hybridize with a subgenomic fragment contained in the L region encoding the viral capsid polypeptides. This could account for the antiviral antibodies found in animals bearing the VX7 carcinoma.

Intraarterial versus intravenous adriamycin in the rabbit Vx-2 tumor system

Intraarterial (IA) chemotherapy can theoretically result in a high tissue level of the drug with reduced systemic toxicity compared with intravenous (IV) administration. The authors compared these two modes of therapy using Adriamycin (doxorubicin) in the rabbit Vx-2 tumor system. Vx-2 was implanted in hind limb muscle, and silastic catheters were placed in the jugular vein and femoral artery. Nuclear imaging of technetium-99m-labeled autologous erythrocytes in nine animals was used to measure the kinetics of tumor blood flow. Presence of tumor increased flow through the involved limb up to threefold. One minute following injection there was no difference in concentration of 99mTc in tumor whether labeled cells were introduced IA or IV. Twelve rabbits received IA (N = 6) or IV (N = 6) Adriamycin (3 mg/kg), while eight animals received normal saline IA or IV as controls. Tumor progressed in all control rabbits, whereas there was an objective or complete response in 83% of animals receiving Adriamycin. One hundred percent of those treated IA responded compared with 67% for IV (P = 0.04). Median time to initial response in animals treated IA was 7 days versus 21 days for those treated IV (P = 0.02). Thus, IA Adriamycin achieves a more complete and more rapid response than the drug given IV. This occurs despite a large tumor blood flow and rapid equilibration using both methods.

Integration and methylation of shope papilloma virus DNA in the transplantable Vx2 and Vx7 rabbit carcinomas

The Shope papilloma virus (SPV) DNA present in SPV-induced benign and malignant rabbit tumors, particularly in the transplantable carcinoma Vx2 and Vx7, was examined with regard to physical states and extent of methylation. Vx2 and Vx7 carcinomas contained 10-22 viral genomes per diploid cell, and domestic and cottontail rabbit papillomas 40-400 and 1000-8000, respectively. The digestion of Vx2 and Vx7 DNA with the restriction enzyme KpnI, which does not cleave SPV DNA, yielded a single virus-specific DNA band about nine times larger than the genome length, but EcoRI, which cuts the circular SPV DNA once, cleaved this DNA to the genome-size fragments. However, three or four weak bands which may contain viral segments linked to cellular sequences were also identified, and at least two were shared by both Vx2 and Vx7 carcinomas. The analysis with a set of MspI and HpaII, which discriminates the methylated DNA sequence -CC*GG-, showed that 10-40% of the sites of viral DNA are methylated in papillomas, 30-80% in primary carcinomas, and more than 90% in the transplantable carcinomas.

Immunology of human papillomavirus: warts

Great progress has been made over the last five years in our understanding of papillomavirus (PV) biology. New technology has enabled investigators to understand the relationship between the PV and its host. The PV cannot be cultured in vitro, and this has led to limitations for those wishing to study the biology of this virus. However, utilizing recombinant DNA technology, investigators now have abundant quantities of human papillomavirus (HPV) DNA for study. Such HPV genomes may be labeled with a radioisotope such as P32 and used as a "probe" in hybridization studies to see if a given tissue contains HPV DNA. No longer are we limited to electron microscopy and immune studies in our efforts to identify HPV within benign or malignant tissues. Ultimately, we hope to understand the relationship between the virus and its host. This paper will concentrate on one aspect of this relationship--the immunology of HPV.

Experimental study on trans-nodal cancer chemotherapy for metastatic lymph nodes

As complete dissection of metastatic lymph nodes in the upper mediastinum is impossible in conventional surgery for esophageal carcinoma, we devised a form of intraoperative local adjuvant cancer chemotherapy for metastatic lymph nodes of the mediastinum, via tracheal bifurcation lymph nodes located at the anatomical pivot in the upper mediastinal lymph flow. Emulsion type bleomycin (BLM) was injected into the bifurcation lymph nodes of mongrel dogs, and BLM was identified in the pulmotracheal lymph nodes within 20 minutes. When the cervicothoracic lymph nodes in the ipsilateral side were dissected beforehand, the BLM levels in the contralateral side doubled those seen in the controls. In rabbits with VX2 carcinoma, the level of BLM decreased in lymph nodes with metastasis, however, the spread was still evident even when about 75 per cent of the nodes were occupied with metastasis.