Epithelial neoplasms of the skin, the cutaneous mucosa and the transitional epithelium in dogs: an immunolocalization study for papillomavirus antigen

Long-Term Culture of Canine Ocular Cells That Maintain Canine Papillomaviruses

Canine ocular papillomas occur on the haired skin of eyelids, conjunctival epithelium, and rarely on the cornea. Using PCR typing assays with canine papillomavirus type-specific primer sets, our study confirmed that the papillomas contained canine papillomavirus type 1. The positive result from a rolling circle amplification assay indicated the CPV1 viral genome in the cells is a circular episomal form. We also successfully established the first canine corneal cell line using the conditional reprogramming method. The cells exhibited an epithelial cell morphology, grew rapidly in vitro, and could be maintained long term. For the continued growth of the canine corneal cells, feeder cells played a more important role than Rho-kinase inhibitor Y-27632. More importantly, the viral CPV1 genome was maintained in the canine corneal cells during the long-term expansion. Unlimited supplies of these cells provide as a model for the study CPV in dog cells, and a platform for drug screening for effective therapies against canine papillomavirus infection in the future.

Development of multiple cutaneous and follicular neoplasms associated with canine papillomavirus type 3 in a dog

A 12-year-old spayed English pointer dog developed multiple skin lesions including pigmented viral plaques, basal cell carcinomas, squamous cell carcinomas and trichoblastomas. Canine papillomavirus type 3 was detected in multiple lesions suggesting common aetiology.

Expression of the hippo signalling pathway effector YAP during canine epidermal tumourigenesis

Cutaneous papilloma (CP) and cutaneous squamous cell carcinoma (CSCC) are frequent epidermal tumours in dogs. In this regard, the study of the deregulated activity of signalling molecules during the epidermal tumourigenesis process could be the basis for the development of novel molecular mechanism-based antitumour treatments for CP and CSCC canine patients. Recent evidence suggests that the development and progression of CP and CSCC involve the dysregulated activation of the Hippo signalling pathway effector YAP. Thus, in the present study, we evaluated the immunohistochemical expression pattern of YAP in sections of tissue microarrays constructed from canine samples of normal epidermis, CP, preneoplastic epidermis, and CSCC. In samples of CP, preneoplastic epidermis, and CSCC, YAP expression was significantly increased relative to normal epidermis. This emerging evidence suggests that the dysregulated activity of the Hippo signalling pathway effector YAP represents a frequent event during canine epidermal tumourigenesis, pointing to this protein as a potential therapeutic target for the treatment of CP and CSCC in dogs.

Aberrant Expression of E-cadherin/β-catenin During Epidermal Tumourigenesis in Dogs

Clinically relevant epidermal tumours in dogs include cutaneous papillomas (CPs) and cutaneous squamous cell carcinomas (CSCCs). The development of CPs and CSCCs involves dysregulation in expression of E-cadherin/β-catenin; however, knowledge about the contribution of these molecules to epidermal tumourigenesis in dogs is limited. This study examined the immunohistochemical expression pattern of E-cadherin/β-catenin in samples of normal canine epidermis, CPs, preneoplastic epidermis and CSCCs, using tissue microarrays, in order to elucidate whether the dysregulated expression of these molecules may contribute to the pathogenesis of clinically relevant epidermal tumours in dogs. We also investigated the correlation between the immunohistochemical expression pattern of E-cadherin/β-catenin in these tissue microarrays to further evaluate whether the disruption of the adherens junction interactions plays a relevant role in canine epidermal tumourigenesis. In samples of CP and preneoplastic epidermis, the membrane immunoreactivity of E-cadherin/β-catenin was conserved, while in CSCC, the immunoreactivity of these molecules was significantly reduced, independently of the tumour location. There was significant correlation between the membrane expression of E-cadherin/β-catenin in CSCC. β-catenin also showed cytoplasmic and nuclear expression in samples of CP, preneoplastic epidermis and CSCC. These results support the hypothesis that dysregulated expression of E-cadherin/β-catenin may play a critical role in the pathogenesis of relevant canine epidermal tumours, not only due to the disruption of the intercellular adherens junctions, but also due to the dysregulated activity of the signalling pathways in which these molecules are involved.

Electrochemotherapy induces tumor regression and decreases the proliferative index in canine cutaneous squamous cell carcinoma

Canine cutaneous squamous cell carcinoma (cSCC) is the most common skin cancer in dogs, and, due to its low metastatic rate, local treatments, such as electrochemotherapy (ECT), promote disease control or even complete remission (CR). This study aimed to evaluate the gene and protein expression of Bcl-2 and Bcl-2 associated X protein (BAX), the proliferative index and clinical parameters in dogs with cSCC subjected to ECT. A prospective nonrandomized clinical study was performed using dogs with naturally occurring cSCC that was treated with ECT. Eighteen lesions from 11 dogs were selected. The tumor size at day 0 (D0) had no impact on survival or prognosis (P > 0.05). Tumor samples had a lower proliferative index after ECT (D21) than before ECT (P = 0.031). The survival of subjects with Ki67 values lower and higher than the Ki67 median value were not significantly different (P > 0.05). Regarding apoptotic markers, there were no significant differences in the gene and protein expression levels of BAX or Bcl-2 at D0 and D21 (P > 0.05) or in the overall survival of subjects with different levels of apoptotic markers. In conclusion, there was no change in BAX or Bcl-2 gene and protein expression in response to ECT at the time points evaluated, but ECT was able to reduce tumor volume and cellular proliferation in cSCC.

Malignant Transformation of a Canine Papillomavirus Type 1-Induced Persistent Oral Papilloma in a 3-Year-Old Dog

This case report describes a rare case of a persistent canine papillomavirus type 1 (CPV-1)-induced oral papilloma that underwent malignant transformation into an oral squamous cell carcinoma (OSCC) in a 3-year-old Labrador retriever cross. Initially, the patient had multiple and multifocal verrucous lesions populating the oral cavity exclusively. The papillomas persisted despite multiple surgical ablations, azithromycin, interferon α-2b, alternative medicines, and off-label drug use of an immunostimulant. After 1 year and 6 months, an aggressive lesion developed at the level of the left mandibular first molar (309) and progressed to a well-differentiated invasive OSCC. The presence of CPV-1 DNA in the OSCC, and the known oncogenic abilities of CPV-1, suggests that this virus might have played a significant role in the emergence of the OSCC that ultimately led to the patient's euthanasia due to poor quality of life. This is the first well-documented case where OSCC has developed from an oral papilloma caused by CPV-1 in which the presence of coinfection by another papillomavirus was excluded by multiple polymerase chain reaction tests using various primers.

Dysregulated expression of the key effectors of the mammalian target of rapamycin signalling pathway in cutaneous papillomas of dogs

Cutaneous papillomas (CP) are one of the most common skin neoplasms in dogs. Different murine models have shown that persistent activation of the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway has a central role in the development and progression of CP. The purpose of this study were to evaluate the immunohistochemical expression pattern of two key molecules involved in the PI3K/Akt/mTOR signalling pathway, pAkt^Ser473 , and pS6^Ser235/236 , on 36 canine specimens of CP using a tissue microarray. The results show that the PI3K/Akt/mTOR signalling pathway is persistently activated in CP of dogs, pointing to this pathway as a potential therapeutic target.

Quantitative Morphology as a Prognostic Factor in Feline Spontaneous Cutaneous Squamous Cell Carcinomas

In a study on cytological specimens from 30 cats with histologically confi rmed cutaneous squamous cell carcinoma, the morphometric variables mean nuclear area (MNA, μm2), mean nuclear perimeter (MNP, μm), mean nuclear diameter (D mean, μm), minimum nuclear diameter (D min, μm) and maximum nuclear diameter (D max, μm) were studied and compared to metastases in regional lymph nodes. The mean values of these parameters were signifi cantly greater in cats with lymph node metastases compared to parameters of tumour cells from cats which were lymph node-negative. A signifi cant positive correlation was observed between all studied morphometric parameters and metastases in the regional lymph nodes. In conclusion, computer -assisted nuclear morphometry could be used as a prognostic method in the diagnosis of spontaneous feline cutaneous squamous cell carcinomas.

Vulvar epithelioid hemangiosarcoma with solar elastosis in a mare

A 15-year-old female gray Appaloosa horse was presented with history of a mass over the right dorsal commissure of vulva for the past 7 months. Based on histopathological examination, and positive staining with factor VIII–related antigen, vimentin, and Verhoeff–van Gieson stain, the vulvar mass was diagnosed as hemangiosarcoma with marked solar elastosis.

Papillomavirus-Associated Cutaneous Neoplasia in Mammals

For humans, strong evidence indicates that some mucosal papillomavirus (PV) types cause genital and oral neoplasia, and weaker evidence suggests that some cutaneous PVs may cause cutaneous squamous cell carcinomas (SCC). For nonhuman species, strong evidence supports a causal role of PVs in the development of feline and equine sarcoids. Likewise, PVs are believed to cause cutaneous SCCs in rabbits, western barred bandicoots, and some rodents. Furthermore, some evidence suggests that PVs may influence the development of both feline and canine cutaneous SCCs. This review discusses the evidence that PVs cause human cutaneous SCCs and the proposed mechanisms for this action. It then reviews preneoplastic and neoplastic skin diseases that are associated with PV infection in nonhuman mammals.

Detection of antibodies against epidermodysplasia verruciformis-associated canine papillomavirus 3 in sera of dogs from Europe and Africa by enzyme-linked immunosorbent assay

The role of papillomaviruses (PVs) in the development of canine cancers is controversial. However, recently a novel canine PV (CPV3) was detected in a dog affected with a condition reminiscent of epidermodysplasia verruciformis (EV). The aim of the present study was to investigate the seroprevalence of CPV3 by using generic enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies against either canine oral PV (COPV) or CPV3. Therefore, the capsid proteins of both PV types were expressed as glutathione S-transferase fusion protein antigens and adsorbed to glutathione-casein-coated ELISA plates. After showing that PV type-specific antibodies could be detected in the sera from dogs with confirmed COPV or CPV3 infection, CPV3- and COPV-seropositive samples were detected in two sets of canine sera collected in Switzerland and South Africa, respectively. We found specific antibodies against COPV and CPV3 among the tested sera and also a large number that were positive for both antigens. The seroprevalences of PV antibodies of 21.9% (COPV) and 26.9% (CPV3) among the tested dogs from South Africa were higher than those among the dogs from Switzerland at 10.5% (COPV) and 1.3% (CPV3). Our data suggest a need for further CPV-related seroepidemiological surveys in different countries, especially in the context of clinical manifestations and possible breed predispositions. For this purpose, the newly developed ELISAs can be a useful tool.

Detection of novel papillomaviruses in canine mucosal, cutaneous and in situ squamous cell carcinomas

Papillomavirus (PV) DNA is frequently uncovered in samples of human skin squamous cell carcinomas (SCC). However, the role of these viruses in the development of such cancers in canine species remains controversial. While approximately 100 human PVs are known, only one single canine oral PV (COPV) has been identified and studied extensively. Therefore, we applied a narrow-range polymerase chain reaction (PCR) suitable for the detection of classical canine and feline PVs, as well as a broad-range PCR, which has been used for the detection of various novel PVs in humans, in order to analyse 42 paraffin-embedded samples, representing three different forms of canine SCCs. Ten samples of skin tissues with various non-neoplastic conditions served as controls. While none of the negative controls reacted positively, PV DNA was discovered in 21% of the tested SCC samples. Interestingly, the classical COPV was amplified from only one sample, while the other positive cases were associated with a variety of thus far unknown PVs. This study suggests that a fraction of canine SCC is infected with PVs and that a genetic variety of canine PVs exists. Therefore, these results will facilitate the future study of the role of PVs in the development of canine skin cancers.

Cellular immunolocalization of gastric and pancreatic lipase in various tissues obtained from dogs

OBJECTIVE

To determine cellular immunolocalization of canine gastric lipase (cGL) and canine pancreatic lipase (cPL) in various tissues obtained from clinically healthy dogs.

SAMPLE POPULATION

Samples of 38 tissues collected from 2 climically healthy dogs.

PROCEDURES

The cGL and cPL were purified from gastric and pancreatic tissue, respectively, obtained from dogs. Antisera against both proteins were developed, using rabbits, and polyclonal antibodies were purified by use of affinity chromatography. Various tissues were collected from 2 healthy dogs. Primary antibodies were used to evaluate histologic specificity. Replicate sections from the collected tissues were immunolabeled for cGL and cPL and examined by use of light microscopy.

RESULTS

Mucous neck cells and mucous pit cells of gastric glands had positive labeling for cGL, whereas other tissues did not immunoreact with cGL. Pancreatic acinar cells had positive labeling for cPL, whereas other tissues did not immunoreact with cPL.

CONCLUSIONS AND CLINICAL RELEVANCE

We concluded that cGL and cPL are exclusively expressed in gastric glands and pancreatic acinar cells, respectively. Also, evidence for cross-immunoreactivity with other lipases or related proteins expressed by other tissues was not found for either protein. Analysis of these data suggests that gastric lipase is a specific marker for gastric glands and that pancreatic lipase is a specific marker for pancreatic acinar cells. These markers may have clinical use in the diagnosis of gastric and exocrine pancreatic disorders, respectively.

Digital papillomatosis in a confined Beagle

Papillomavirus-induced papillomas were diagnosed on multiple digits of all 4 feet of a young Beagle. No other cutaneous or oral involvement was identified. Papillomavirus antigen was confirmed by immunoperoxidase localization within keratinocyte nuclei. In addition to the typical basophilic intranuclear inclusions associated with papillomavirus infections, keratinocytes within the papillomas contained large, eosinophilic cytoplasmic inclusions that previously have been described in a Boxer with cutaneous lesions associated with a papillomavirus infection. The papillomas in this Beagle regressed completely within 2 months of the initial diagnosis.

Molecular characteristics of cutaneous papillomavirus from the canine pigmented epidermal nevus

To investigate the relation between the canine pigmented epidermal nevus (PEN) and cutaneous papillomavirus, we cloned and sequenced the L1 gene of papillomavirus from the canine pigmented epidermal nevus (PEN). Amplification of DNA sample with the L1 consensus primers yielded an expected fragment of approximately 450-bp. The nucleotide sequences of the fragment showed about 64% of sequence similarity to the L1 region of human papillomavirus isolate CP6108 and less than 57% sequence similarity to those of canine oral papillomavirus (COPV). In situ hybridization determined the presence of papillomavirus DNA mainly in the upper stratum granulosum of skin in this case. The results indicated that the canine cutaneous papillomavirus from the PEN lesion was genetically close to human papillomavirus rather than COPV.

Canine viral infections

The ophthalmic effects of viral infection are varied. With the added possibility for pathologic effects of attenuated vaccine viruses, the diagnosis of viral diseases can be a challenge. In many cases, ocular manifestations can provide added support to a presumptive diagnosis of viral disease, thereby underscoring the benefit of thorough ophthalmic examination of any animal with nonspecific signs of illness.