Molecular cytogenetic analysis of a novel high-grade canine T-lymphoblastic lymphoma demonstrating co-expression of CD3 and CD79a cell markers

Concordance of the Histopathologic Diagnosis of Concurrent Duodenal and Ileal Biopsy Specimens in Dogs

Histopathologic discordance between gastrointestinal (GI) locations in canine chronic inflammatory enteropathy (CIE) has prompted recommendations to biopsy both the duodenum and ileum, while further evaluation is required for non-CIE. We aimed to determine the concordance of histopathologic diagnosis between duodenal and ileal endoscopic or full-thickness biopsy specimens for all dogs with CIE and GI neoplasia and to assess the association between histopathologic discordance between GI locations with clinicopathologic variables. Seventy-nine dogs were eligible, with endoscopic (74) or full-thickness (5) biopsy specimens. Clinicopathological data were recorded for all dogs. Concordance of histopathologic diagnosis was retrospectively assessed for concurrent duodenal and ileal biopsy specimens by a single board-certified veterinary pathologist using the modified World Small Animal Veterinary Association (WSAVA) Gastrointestinal Standardization Group guidelines. Sixty-seven dogs were diagnosed with CIE and 5 with enteric-associated T-cell lymphoma-2 (EATL-2). Concordance of histologic diagnosis between duodenal and ileal sites was similar between endoscopic (73.0%) and full-thickness (80.0%) biopsy groups. For the CIE cases, lymphoplasmacytic enteritis had the highest concordance (73.0%) and eosinophilic enteritis the least (16.7%). Of the 5 neoplastic cases, 5/5 (100%) were present at the duodenum but only 3/5 (60%) in the ileum. No clinicopathologic variables demonstrated a statistically significant association with discordance. We conclude that the level of discordance necessitates concurrent biopsy of both duodenum and ileum in all dogs with chronic GI signs. The rate of EATL-2 was lower than rates reported for cats.

Identifying Lung Cancer Cell Markers with Machine Learning Methods and Single-Cell RNA-Seq Data

Non-small cell lung cancer is a major lethal subtype of epithelial lung cancer, with high morbidity and mortality. The single-cell sequencing technique plays a key role in exploring the pathogenesis of non-small cell lung cancer. We proposed a computational method for distinguishing cell subtypes from the different pathological regions of non-small cell lung cancer on the basis of transcriptomic profiles, including a group of qualitative classification criteria (biomarkers) and various rules. The random forest classifier reached a Matthew’s correlation coefficient (MCC) of 0.922 by using 720 features, and the decision tree reached an MCC of 0.786 by using 1880 features. The obtained biomarkers and rules were analyzed in the end of this study.

CD3 and CD20 co-expression in a case of canine peripheral T-cell lymphoma with prominent cardiac and peripheral nerve involvement

An 8-y 9-mo-old male Pug dog was presented because of anorexia, hindlimb ataxia, vomiting, and progressive weight loss. Clinical examinations revealed atrophic hindlimb muscles with decreased postural reaction, enlargement of the cardiac silhouette and megaesophagus on radiograph, and reduced cardiac contractility on ultrasonography. The dog died 10 d after the initial examination, and an autopsy was performed. Grossly, the heart was enlarged, with multifocal-to-coalescing extensive plaque-like areas of discoloration on the epicardial surface. On cross-section, the ventricles were moderately dilated, and discoloration extended into the myocardium. Peripheral lymph nodes were of normal size. Histologically, atypical lymphoid cells replaced the myocardium and also extensively infiltrated peripheral nerve bundles in various organs. With immunohistochemistry, the neoplastic cells exhibited strong immunoreactivity for CD3 and CD20, and were negative for CD8, granzyme B, CD79α, and Pax5. Double-label immunofluorescence confirmed co-expression of CD3 and CD20 by the neoplastic cells. Molecular clonality analysis presented a clonal T-cell receptor gamma gene rearrangement. The case was diagnosed as a CD3+/CD20+ peripheral T-cell lymphoma with prominent cardiac and peripheral nerve involvement, indicating neurolymphomatosis.

Evaluation of Pax5 expression and comparison with BLA.36 and CD79αcy in feline non-Hodgkin lymphoma

Paired box gene 5 (Pax5) is a widely used B-cell marker for human and canine non-Hodgkin's lymphoma (nHL); however, in the literature there is only one case report using Pax5 in a cat B-cell lymphoma. The purposes of this study were to investigate the expression and detection of B-cell specific activator protein (BSAP) using a monoclonal anti-Pax5 antibody in feline nHL (FnHL) tissue samples to evaluate its diagnostic relevance as a B-cell marker. A total of 45 FnHL samples in 45 cats were evaluated. B-cell lymphoma was the most common immunophenotype (51.1%) for all the samples and T-cell the most common immunophenotype (64.3%) for the gastrointestinal (GI) form. Pax5 stained 82.6% of all B-cell lymphomas and no expression was found in any of the T-cell lymphomas. Anti-Pax5 antibody staining in FnHL is similar to that reported in human and canine counterparts and may offer an excellent B-cell marker in cats.

Vertebral Polyostotic Lymphoma in a Young Dog

An unusual clinical presentation of lymphoma with vertebral involvement in a dog is reported. A 20-month-old intact female Golden Retriever presented with progressive paraparesis and anorexia. Complete blood count and serum biochemistry profile demonstrated pancytopenia and hypercalcemia. Ventral fusion of the lumbar vertebrae by new bony tissue deposition was evident on X-ray and CT scan. Fine needle aspiration revealed neoplastic lymphoid cells in lymph nodes and bone marrow. Histologically, vertebral bone and osteophytes, liver, bone marrow, kidney, and lymph nodes were diffusely infiltrated by neoplastic, lymphoid cells, with scant cytoplasm and round hyperchromatic nuclei. Polyostotic and medullary T-cell lymphoma with spondylosis was diagnosed. Lymphoma mainly affecting bone is uncommon in the dog. The present case differs from previously described polyostotic lymphomas in clinical signs of the disease, mainly attributable to spondylarthrosis. In addition, lymphomatous proliferation was associated with osteoproductive lesions of the vertebrae.

Comparative genomic hybridization in detection of DNA changes in canine lymphomas

In this study, chromosomal imbalances in tumor tissues (lymphomas) and nucleotide changes in tumor suppressor TP53 were studied in a Bernese Mountain dog bitch and a cross breed bitch. Using comparative genomic hybridization, numerous chromosomal rearrangements were detected, which indicated the heterogeneity in tumor growth: in the cross breed bitch, a deletion on the chromosome 9, and duplications on chromosomes 5, 8 and 17 have been found. In the Bernese Mountain Dog bitch, losses on chromosomes 1, 5, 8, 12, 18, 22, 27, 29 and gains on chromosomes 1, 2, 9, 11, 15, 16, 18, 20, 23, 24, 25, 28, 29, 30, 34, 36, 37 and 38 were identified. With the sequencing of the TP53 gene, one silent mutation, transition A/G at position 138 in exon 5 was detected, without changing the amino acid.

The dog as a possible animal model for human non-Hodgkin lymphoma: a review

Lymphoma represents the most frequent hematopoietic cancer in dogs, and it shows significant overlap with the human disease. Several environmental factors have been associated with canine lymphoma, suggesting that they may contribute to lymphomagenesis. Canine lymphoma often presents in advanced stage (III-V) at diagnosis and, most commonly, has an aggressive clinical course requiring prompt treatment, which relies on the use of polychemotherapy. In this review, we will summarize the state-of-the-art of canine lymphoma epidemiology, pathobiology, diagnostic work-up and therapy, and will highlight the links to the corresponding human disease, providing evidence for the use of dog as an animal model of spontaneous disease.

Metastatic angioinvasive lymphoma (lymphomatoid granulomatosis) in a cat

A subcutaneous mass removed from the right rear leg of a 17-year-old, spayed, female Domestic Shorthair cat was characterized histopathologically by granulomatous inflammation, sheets of large atypical lymphoid cells, and necrosis. The walls of the small and medium caliber blood vessels were invaded transmurally by atypical lymphoid cells. A diagnosis of angioinvasive lymphoma (AIL), or lymphomatoid granulomatosis, was made based on histopathologic findings. The cat was euthanized 2 months later because of recurrence of the mass and elevated serum alanine aminotransferase activity, and a necropsy was performed. The histopathologic lesion of AIL was seen in the skin and subcutis of the right rear leg, and neoplastic cell infiltrates were seen in adjacent skeletal muscle, right superficial inguinal lymph node, liver, and spleen. By immunohistochemistry, variable numbers of neoplastic cells expressed B-lymphocyte antigen 36 (BLA36) or cluster of differentiation (CD)3 markers, indicative of B- and T-cell lineages, respectively. Neoplastic cells were uniformly positive for vimentin and uniformly negative for cytokeratins and myeloid/histiocytic antigen. Although the cat had received a Rabies virus vaccine subcutaneously in the right rear leg 6 months earlier, the AIL lesion was not typical of vaccine-induced sarcomas. The AIL in this cat was unusual because the extrapulmonary metastases involved the skin and subcutis.

Pax5 immunostaining in paraffin-embedded sections of canine non-Hodgkin lymphoma: a novel canine pan pre-B- and B-cell marker

The Pax5 gene encodes the B-cell specific activator protein (BSAP), a member of the highly conserved paired box (PAX)-domain family of transcription factors and a key regulator in the development and differentiation of B-cells. Pax5 serves as a valuable B-cell marker in the classification of human lymphoma patients as it is restricted to lymphomas of B-cell lineage. In dogs, detection of Pax5 protein in lymphoma tissue has not been reported. Therefore, we have investigated the expression and detection of BSAP using a monoclonal anti-Pax5 antibody (anti-BSAP, clone 24) in canine lymphoma tissue samples to evaluate its diagnostic relevance as a B-cell marker. A series of 25 lymph nodes from 23 canine non-Hodgkin lymphoma patients, a reactive canine lymph node, and a normal non-reactive canine lymph node, were evaluated. All B-cell non-Hodgkin lymphomas (15) were found to express Pax5 protein. In addition, there was a strong correlation between Pax5 and CD79a expression. Three CD3 positive and five CD3 and CD79a positive lymphomas were immunophenotypically negative for anti-Pax5, indicating a T-cell lineage. In conclusion, anti-Pax5 antibody may offer an excellent B-cell marker in canine lymphomas.

Canine cytogenetics--from band to basepair

Humans and dogs have coexisted for thousands of years, during which time we have developed a unique bond, centered on companionship. Along the way, we have developed purebred dog breeds in a manner that has resulted unfortunately in many of them being affected by serious genetic disorders, including cancers. With serendipity and irony the unique genetic architecture of the 21st century genome of Man's best friend may ultimately provide many of the keys to unlock some of nature's most intriguing biological puzzles. Canine cytogenetics has advanced significantly over the past 10 years, spurred on largely by the surge of interest in the dog as a biomedical model for genetic disease and the availability of advanced genomics resources. As such the role of canine cytogenetics has moved rapidly from one that served initially to define the gross genomic organization of the canine genome and provide a reliable means to determine the chromosomal location of individual genes, to one that enabled the assembled sequence of the canine genome to be anchored to the karyotype. Canine cytogenetics now presents the biomedical research community with a means to assist in our search for a greater understanding of how genome architectures altered during speciation and in our search for genes associated with cancers that affect both dogs and humans. The cytogenetics 'toolbox' for the dog is now loaded. This review aims to provide a summary of some of the recent advancements in canine cytogenetics.

A Cytogenetically Characterized, Genome-Anchored 10-Mb BAC Set and CGH Array for the Domestic Dog

The generation of a 7.5x dog genome assembly provides exciting new opportunities to interpret tumor-associated chromosome aberrations at the biological level. We present a genomic microarray for array comparative genomic hybridization (aCGH) analysis in the dog, comprising 275 bacterial artificial chromosome (BAC) clones spaced at intervals of approximately 10 Mb. Each clone has been positioned accurately within the genome assembly and assigned to a unique chromosome location by fluorescence in situ hybridization (FISH) analysis, both individually and as chromosome-specific BAC pools. The microarray also contains clones representing the dog orthologues of 31 genes implicated in human cancers. FISH analysis of the 10-Mb BAC clone set indicated excellent coverage of each dog chromosome by the genome assembly. The order of clones was consistent with the assembly, but the cytogenetic intervals between clones were variable. We demonstrate the application of the BAC array for aCGH analysis to identify both whole and partial chromosome imbalances using a canine histiocytic sarcoma case. Using BAC clones selected from the array as probes, multicolor FISH analysis was used to further characterize these imbalances, revealing numerous structural chromosome rearrangements. We outline the value of a combined aCGH/FISH approach, together with a well-annotated dog genome assembly, in canine and comparative cancer studies.

A novel canine lymphoma cell line: a translational and comparative model for lymphoma research

A novel canine lymphoma cell line, OSW, was established from the malignant pleural effusion of a dog with peripheral T-cell lymphoma. The immunoprofile as determined by flow cytometry was as follows: positive for CD45, CD49d, CD18, CD11a; weakly positive for CD11b, CD11c, CD11d; and negative for CD45RA, CD1a, CD1c, CD3, TCRalphabeta, TCRgammadelta, CD4, CD5, CD8a, CD8b, CD90(Thy1), CD21, MHCII, CD14(TUK4), CD34, and MPO. Immunocytochemistry of cytospin preparations was negative for cytoplasmic CD3, CD79a, and MPO, but was positive for CD20. The cell line had an oligoclonal T-cell receptor gamma (TCRgamma) gene rearrangement. Array comparative genomic hybridization (aCGH) and single locus probe (SLP) analysis showed that there were copy number increases of loci on dog chromosome 13 (CFA 13), and copy number decreases were evident for regions of CFA 11, 22, 26, 30 and 32, which include several of the more common chromosomal aberrations reported previously in canine lymphoma. The OSW cell line grows rapidly in vitro and is tumorigenic as a xenograft in SCID/NOD mice. OSW represents one of only a few reported canine lymphoma cell lines and is the most thoroughly characterized. This cell line and xenograft represent significant in vitro and in vivo models, respectively, for comparative and translational lymphoma research.

Construction of a 2-Mb resolution BAC microarray for CGH analysis of canine tumors

Recognition of the domestic dog as a model for the comparative study of human genetic traits has led to major advances in canine genomics. The pathophysiological similarities shared between many human and dog diseases extend to a range of cancers. Human tumors frequently display recurrent chromosome aberrations, many of which are hallmarks of particular tumor subtypes. Using a range of molecular cytogenetic techniques we have generated evidence indicating that this is also true of canine tumors. Detailed knowledge of these genomic abnormalities has the potential to aid diagnosis, prognosis, and the selection of appropriate therapy in both species. We recently improved the efficiency and resolution of canine cancer cytogenetics studies by developing a small-scale genomic microarray comprising a panel of canine BAC clones representing subgenomic regions of particular interest. We have now extended these studies to generate a comprehensive canine comparative genomic hybridization (CGH) array that comprises 1158 canine BAC clones ordered throughout the genome with an average interval of 2 Mb. Most of the clones (84.3%) have been assigned to a precise cytogenetic location by fluorescence in situ hybridization (FISH), and 98.5% are also directly anchored within the current canine genome assembly, permitting direct translation from cytogenetic aberration to DNA sequence. We are now using this resource routinely for high-throughput array CGH and single-locus probe analysis of a range of canine cancers. Here we provide examples of the varied applications of this resource to tumor cytogenetics, in combination with other molecular cytogenetic techniques.

Lineage differentiation of canine lymphoma/leukemias and aberrant expression of CD molecules

Multiparameter flow cytometry analysis and specific cluster differentiation (CD) molecules were used to determine the expression profiles of B- and T-cell antigens on lymph node preparations from 59 dogs with generalized or multisystemic lymphoma. Lymph node samples from 11 healthy dogs were labeled to validate the specificity of antibodies and to formulate guidelines for interpretation of the results obtained from lymphoma samples. In normal lymph nodes, T-lymphocytes expressing CD3, CD4, or CD8 beta represented 59+/-11%, 43+/-8%, or 16+/-5% of the total cells, whereas B-lymphocytes expressing either CD21 or surface IgM (IgM) represented 37+/-9% or 14+/-5%, respectively. Small lymphocytes could be distinguished from large lymphocytes by forward light scatter. Of the patient samples 29 different breeds were represented with Golden and Labrador retriever being the most common. The lymphoma samples segregated into three groups based on CD antigen expression. Thirty cases predominantly expressed one or more combinations of CD79a, IgM, and CD21 representing a B-cell lineage. Three B-cell cases also expressed the stem cell antigen, CD34. Sixteen cases expressed one or more combinations of CD3, CD4, and CD8 consistent with a T-cell lineage and CD3+CD4+CD8--phenotype was the most common. Thirteen cases showed a mixed expression profile for T- and B-cell antigens and in three cases CD14 was highly expressed. Clinical response was poorest for T-cell lymphomas. Leukemic states occurred in all three phenotypes; but mixed cell cases had the greatest proportion. Dual immunofluorescence staining confirmed co-expression of T-cell (CD3) and B-cell antigens (CD79a or CD21) on neoplastic lymphocytes of six mixed cell cases. In one mixed cell case, dual immunostaining identified lymphocyte populations that stained mutually exclusive for CD79a and CD3. Six mixed cell lymphomas tested by PCR showed clonality for rearranged antigen receptor. Four cases that were CD79a+CD3+ had TCRgamma chain gene rearrangements, whereas two cases that were CD3+CD8+CD21+ had Ig heavy chain rearrangement. One case expressing multiple CD molecules (CD3+CD8+CD21+CD14+) was PCR negative for both Ig and TCRgamma gene rearrangement and could not be classified into a B- or T-cell lineage. We show for the first time co-expression of B- and T-cell markers on lymphoma cells that had specific T- or B-cell gene rearrangements. These findings suggest that aberrant CD molecule expression is not an uncommon finding in canine lymphomas and is a useful diagnostic marker for malignancy.

Karyotype of canine soft tissue sarcomas: a multi-colour, multi-species approach to canine chromosome painting

Many canine tumour types represent useful models for tumours also found in humans. Studies of chromosomal abnormalities in canine tumours have been impeded by the complexity of the canine karyotype (2n = 78), which has made accurate identification of rearranged chromosomes difficult and laborious. To overcome this difficulty we have developed a seven-colour paint system for canine chromosomes, with six sets of chromosome paints covering all chromosomes except Y. Several pairs of canine autosomes co-locate in the flow karyotype. To distinguish these autosomes from each other, paint sets were supplemented with chromosomes of red fox and Japanese raccoon dog. Paints were used in fluorescence in-situ hybridization to analyse karyotypes in fourteen canine soft tissue sarcomas. Rearranged karyotypes were observed in seven tumours, but there was evidence for loss of rearrangement during tissue culture. Five tumours had rearrangements involving four chromosomes or fewer; one, a chondrosarcoma, had lost seven chromosomes whilst the last, a spindle cell sarcoma, had rearrangements involving eighteen chromosome pairs. The paint sets described here facilitate the complete cytogenetic analysis of balanced translocations and other inter-chromosomal rearrangements in canine tumours. We believe that this is the first canine tumour series to be subjected to this level of analysis.

Canine Lymphomas: a Morphological and Immunohistochemical Study of 55 Cases, with Observations on p53 Immunoexpression

The purpose was to determine the immunophenotype of canine lymphomas (CLs) classified according to the WHO nomenclature for domestic animals, and to relate these findings to the immunoexpression of p53 protein. Lymphomas were immunophenotyped with antibodies to CD79a, CD3, and p53 protein, suitable for paraffin wax-embedded tissue sections. Of 55 cases, 40 (72.7%) were of the B-cell phenotype, 12 (21.8%) of the T-cell phenotype, and three (5.4%) were non-B-non-T lymphomas. Of the 40 B-cell lymphomas, 31 were of the large B-cell type, six were lymphoplasmacytic, one lymphocytic, one follicular (grade II) and one unclassified low-grade. One of the peripheral T-cell lymphomas was morphologically consistent with anaplastic large cell lymphoma. Immunolabelling for p53 occurred in 24 B-cell and seven T-cell lymphomas. Lymphomas with high grade histology showed a significantly increased frequency of p53 positivity (P = 0.01). Positivity for p53 (more than 10% positive cells) tended to be associated with the T-cell phenotype (P = 0.06). Mean patient age was significantly higher in p53-positive cases (P = 0.02). These data are comparable with findings in human lymphomas.

A canine cancer-gene microarray for CGH analysis of tumors

As with many human cancers, canine tumors demonstrate recurrent chromosome aberrations. A detailed knowledge of such aberrations may facilitate diagnosis, prognosis and the selection of appropriate therapy. Following recent advances made in human genomics, we are developing a DNA microarray for the domestic dog, to be used in the detection and characterization of copy number changes in canine tumors. As a proof of principle, we have developed a small-scale microarray comprising 87 canine BAC clones. The array is composed of 26 clones selected from a panel of 24 canine cancer genes, representing 18 chromosomes, and an additional set of clones representing dog chromosomes 11, 13, 14 and 31. These chromosomes were shown previously to be commonly aberrant in canine multicentric malignant lymphoma. Clones representing the sex chromosomes were also included. We outline the principles of canine microarray development, and present data obtained from microarray analysis of three canine lymphoma cases previously characterized using conventional cytogenetic techniques.

Chromosome aberrations in canine multicentric lymphomas detected with comparative genomic hybridisation and a panel of single locus probes

Recurrent chromosome aberrations are frequently observed in human neoplastic cells and often correlate with other clinical and histopathological parameters of a given tumour type. The clinical presentation, histology and biology of many canine cancers closely parallels those of human malignancies. Since humans and dogs demonstrate extensive genome homology and share the same environment, it is expected that many canine cancers will also be associated with recurrent chromosome aberrations. To investigate this, we have performed molecular cytogenetic analyses on 25 cases of canine multicentric lymphoma. Comparative genomic hybridisation analysis demonstrated between one and 12 separate regions of chromosomal gain or loss within each case, involving 32 of the 38 canine autosomes. Genomic gains were almost twice as common as losses. Gain of dog chromosome (CFA) 13 was the most common aberration observed (12 of 25 cases), followed by gain of CFA 31 (eight cases) and loss of CFA 14 (five cases). Cytogenetic and histopathological data for each case are presented, and cytogenetic similarities with human non-Hodgkin's lymphoma are discussed. We have also assembled a panel of 41 canine chromosome-specific BAC probes that may be used for accurate and efficient chromosome identification in future studies of this nature.