BackgroundGastrointestinal stromal tumors (GISTs) are common mesenchymal neoplasms in the gastrointestinal tract of humans and dogs. Little is known about the pathogenesis of these tumors. This study evaluated the role of c-KIT in canine GISTs; specifically, we investigated activating mutations in exons 8, 9, 11, 13, and 17 of c-KIT and exons 12, 14, and 18 of platelet-derived growth factor receptor, alpha polypeptide (PDGFRA), all of which have been implicated in human GISTs.MethodsSeventeen canine GISTs all confirmed to be positive for KIT immunostaining were studied. Exons 8, 9, 11, 13 and 17 of c-KIT and exons 12, 14, and 18 of PDGFRA, were amplified from DNA isolated from formalin-fixed paraffin-embedded samples.ResultsOf these seventeen cases, six amplicons of exon 11 of c-KIT showed aberrant bands on gel electrophoresis. Sequencing of these amplicons revealed heterozygous in-frame deletions in six cases. The mutations include two different but overlapping six base pair deletions. Exons 8, 9, 13, and 17 of c-KIT and exons 12, 14, and 18 of PDGFRA had no abnormalities detected by electrophoresis and sequencing did not reveal any mutations, other than synonymous single nucleotide polymorphisms (SNPs) found in exon 11 of c-KIT and exons 12 and 14 of PDGFRA.ConclusionsThe deletion mutations detected in canine GISTs are similar to those previously found in the juxtamembrane domain of c-KIT in canine cutaneous mast cell tumors in our laboratory as well as to those reported in human GISTs. Interestingly, none of the other c-KIT or PDGFRA exons showed any abnormalities in our cases. This finding underlines the critical importance of c-KIT in the pathophysiology of canine GISTs. The expression of KIT and the identification of these activating mutations in c-KIT implicate KIT in the pathogenesis of these tumors. Our results indicate that mutations in c-KIT may be of prognostic significance and that targeting KIT may be a rational approach to treatment of these malignant tumors. This study further demonstrates that spontaneously occurring canine GISTs share molecular features with human GISTs and are an appropriate model for human GISTs.

Canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas have been previously diagnosed as gastrointestinal stromal tumors (GIST), leiomyosarcomas, or nonspecified spindle cell sarcomas, but diagnostic criteria for each entity are poorly defined. We propose a classification for canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas based on microscopic, immunohistochemical, and molecular characteristics. Applying the classification to 40 canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas documented its diagnostic and prognostic value. Eighteen (45%) sarcomas were classified as GIST based on positive KIT immunoreactivity. All GISTs were positive for vimentin, 14 (78%) were positive for S-100, and 6 (33%) were positive for smooth muscle actin (SMA). In contrast to their human counterparts, canine GISTs occurred mainly in the small intestine (67%) but commonly metastasized (5/18) to liver, lymph nodes, and omentum. Six GISTs had an activated KIT mutation in exon 11 of c-Kit, but no mutations were detected in exons 8, 9, 13, and 17. Twelve (30%) sarcomas were classified as leiomyosarcomas based on positive labeling for SMA and negative labeling for KIT. Four of these neoplasms were well differentiated leiomyosarcomas characterized by weak to no labeling for vimentin, and 8 were poorly differentiated leiomyosarcomas characterized by strong labeling for vimentin. None of the leiomyosarcomas metastasized, but poorly differentiated leiomyosarcomas had a higher risk of local invasion. Ten (25%) sarcomas were classified as non-GIST/nonleiomyosarcomas that were negative for KIT and SMA but positive for vimentin and either S-100 and/or PGP 9.5. These neoplasms most likely represent sarcomas of neurogenic differentiation resembling Schwann cells or perineurial or endoneurial fibroblasts, respectively.

BackgroundHistiocytic sarcoma is a rare disorder in humans, however it is seen with appreciable frequency in certain breeds of dogs, such as Bernese mountain dog. The purpose of this study was to fully characterize a novel canine histiocytic sarcoma cell line, and utilize it as a tool to screen for potential therapeutic drugs.MethodsThe histiocytic sarcoma cell line was characterized by expression of cellular markers as determined by immunohistochemistry and flow cytometry techniques. The neoplastic cells were also evaluated for their capability of phagocytizing beads particles, and their potential to grow as xenograft in an immunodeficient mouse. We investigated the in vitro cytotoxic activity of a panel of thirteen compounds using the MTS proliferation assay. Inhibitory effects of different drugs were compared using one-way ANOVA, and multiple means were compared using Tukey’s test.ResultsNeoplastic cells expressed CD11c, CD14, CD18, CD45, CD172a, CD204, MHC I, and vimentin. Expression of MHC II was upregulated after exposure to LPS. Furthermore, the established cell line clearly demonstrated phagocytic activity similar to positive controls of macrophage cell line. The xenograft mouse developed a palpable subcutaneous soft tissue mass after 29 days of inoculation, which histologically resembled the primary neoplasm. Dasatinib, a tyrosine kinase pan-inhibitor, significantly inhibited the growth of the cells in vitro within a clinically achievable and tolerable plasma concentration. The inhibitory response to dasatinib was augmented when combined with doxorubicin.ConclusionsIn the present study we demonstrated that a novel canine histiocytic sarcoma cell line presents a valuable tool to evaluate novel treatment approaches. The neoplastic cell line favorably responded to dasatinib, which represents a promising anticancer strategy for the treatment of this malignancy in dogs and similar disorders in humans.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4132-0) contains supplementary material, which is available to authorized users.

The positive identification of these genes demonstrates that our IVET systems are powerful tools for studying H. pylori gene expression in the host environment.

Histiocytic sarcoma in people is an uncommon and highly aggressive hematopoietic malignancy that accounts for less than 1% of all non-Hodgkin's lymphomas. Regardless of treatment, patients invariably carry a poor prognosis and a high mortality rate. The low number of cases limits investigations for more efficacious forms of treatment for this disorder. To date, there is no human histiocytic sarcoma cell line available for research purposes. Therefore, the establishment of a representative cell line would be highly beneficial. In the present study, we established a cell line from a tumor in a Bernese mountain dog that was morphologically characterized as a malignant histiocytic sarcoma. The diagnosis was further supported by the positive cellular expression of CD18 and vimentin by immunohistochemistry, and CD11c and MHC II by flow cytometry techniques. Together, the expression of these markers indicated a dendritic cell origin, in accordance to the cell type observed in the majority of histiocytic sarcoma cases in dogs. The established cell line has been maintained in tissue culture for a minimum of 50 passages over 12 months in RPMI 1640 medium supplemented with 15% heat-inactivated fetal bovine serum. Results from a pHrodo™ E. coli Bioparticles® assay indicated that the cells had phagocytic behavior. Furthermore, the cell line was successfully transplantable as a xenograft in immunodeficient mice when injected subcutaneously. A palpable tumor was observed within two weeks of injection and the tumor retrieved from the mice was histopathologically similar to the primary tumor. Finally, we performed cytotoxic assays in vitro with classical chemotherapeutic agents and novel therapeutic drugs, including tyrosine kinase inhibitors. The results from these assays demonstrated that dasatinib, a receptor tyrosine kinase pan-inhibitor, was able to significantly inhibit the growth of the cells in vitro within a clinically achievable, and tolerable plasma concentration. Interestingly, the antiproliferative response to dasatinib was augmented when combined to doxorubicin, a classical chemotherapeutic agent, indicating the potential benefits of drug combination for the treatment of this malignancy. In this study we successfully established a canine histiocytic sarcoma cell line that can be used as model for translational studies for similar disorders in humans. In addition, studies that require a cell line derived from dendritic cells can also benefit from this new established cell line. Citation Format: Marilia Takada, Maciej Parys, Emmalena Gregory-Bryson, Vilma Yuzbasiyan-Gurkan. A novel canine histiocytic sarcoma cell line provides a potential path to effective treatments with relevance for translational and comparative studies in humans. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3931. doi:10.1158/1538-7445.AM2014-3931

Histiocytic diseases encompass a spectrum of proliferative diseases in humans and dogs. While relatively rare in the human, histiocytic diseases are quite prevalent in certain breeds of dog. In the dog, these diseases range from benign histiocytoma to the malignancy, histiocytic sarcoma (HS). Disseminated HS has a poor prognosis and lacks effective treatment options. The goal of this study is to unravel the mechanisms of tumorigenesis in histiocytic diseases by analyzing the differential expression of microRNAs (miRNAs) along the spectrum of canine histiocytic diseases. As regulators of gene expression, miRNAs will provide insight into the pathways for tumorigenesis in histiocytic malignancies as compared to benign histiocytic diseases. MiRNA profiling of canine histiocytic diseases was conducted on cases of reactive histiocytosis, histiocytic sarcoma, and hemophagocytic histiocytic sarcoma. These samples were compared to normal canine histiocytes derived from peripheral blood. Based upon analysis of the profiling data, several miRNAs were selected for verification and quantification by quantitative reverse transcription PCR. The expression of the known canine miRNAs was evaluated by miRNA array. Data analysis with unsupervised clustering resulted in miRNA expression pattern clusters that were similar to the disease groups. The miRNA profiling data revealed three miRNA targets that were significantly upregulated in all cases as compared to normal canine histiocytes. Functional studies of these miRNAs are underway. These findings support the hypothesis that each histiocytic disease entity has a unique miRNA profile. These miRNAs and/or genes in the pathways they regulate may be targeted for novel and effective therapies. Comparative studies have the potential to elucidate HS tumorigenesis, and improve clinical outcome in dogs and humans. Citation Format: Emmalena Gregory-Bryson, Maciej Parys, Matti Kiupel, Vilma Yuzbasiyan-Gurkan. Identification of critical microRNA regulated pathways in histiocytic diseases. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5288. doi:10.1158/1538-7445.AM2013-5288

Canine histiocytic sarcoma is an aggressive and uniformly-fatal round-cell neoplasm. The localized, peri-articular form of the disease (PAHS) appears to have statistically significant prolonged survival, when compared to the non - peri-articular form of the disease (non-PAHS). Knowledge of the molecular basis for the aggressiveness of the canine histiocytic sarcoma is foundational for developing effective treatments. The aim of this study was to characterize the molecular expression profiles of the different sub-types of the disease. Canine patients, with spontaneously-arising histiocytic sarcoma, were recruited for the study. Tumor tissue samples and peripheral blood were obtained and used for primary cell line development and gene expression analysis. Eight PAHS and 8 non-PAHS tumor samples were selected. RNA extraction, amplification and labeling were performed using standard techniques. Raw gene expression values were obtained using the Affymetrix GeneChip Canine Genome 2.0 Array. Background correction, normalization, PM correction, summarization, and expression analysis were performed using R/affy/limma. Gene set analysis was performed using BRB-ArrayTools, and the Molecular Signatures Database (MSigDB), to investigate gene ontology groups of genes whose expression was differentially regulated. Primary cell lines from tumor biopsies and peripheral blood samples were developed and characterized based on cellular morphology, growth characteristics, and immunophenotyping. In our gene expression array experiments, we identified specific gene transcripts that are more likely to represent true and biologically meaningful differences in expression levels between PAHS and non-PAHS. More specifically, metallopeptidase genes, and homeobox domain gene expression levels were enriched in the PAHS group, while ATP-binding cassette genes, and interleukin 1 receptor signaling gene expression levels were enriched in the non-PAHS group. Our results suggest presence of gene expression signatures that can provide insight in the diverse biologic behavior of the disease and highlight canine spontaneous tumors in understanding tumor biology. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5092. doi:1538-7445.AM2012-5092

Histiocytic diseases encompass a spectrum of proliferative diseases in humans and dogs. While these orphan malignancies are rare in the human, histiocytic diseases are relatively frequent in certain breeds of dog. In the dog, these diseases range from benign histiocytoma to malignant histiocytic sarcoma (HS). Disseminated HS has a poor prognosis and lacks effective treatment options in both humans and dogs. The overall goal of this study is to unravel the mechanisms of tumorigenesis in histiocytic diseases and identify better treatments. Our studies have focused on microRNAs (miRNAs), which are master regulators of gene expression and may have a significant role in tumorigenesis in histiocytic diseases. MiRNA profiling of canine histiocytic diseases was conducted on cases of reactive histiocytosis, HS, and hemophagocytic HS. These samples were compared to normal canine histiocytes derived from peripheral blood or peritoneal fluid. Several miRNAs were identified to be upregulated in the disease samples and were selected for validation by qRT-PCR. From these results, two miRNA targets were selected for further evaluation. We are probing the significance of the upregulation of these miRNAs by inhibiting their function in canine HS cell lines using chemical miRNA inhibitors and sponge constructs designed to competitively bind the upregulated miRNAs, thus preventing them from acting on their targets. Our results to date indicate that inhibiting these miRNAs in the canine HS cell line, DH82, decreases growth rate by as much as 39%. Studies into other aspects of tumorigenicity potentially affected by the inhibition of these miRNAs are underway. Our preliminary data suggests these miRNAs themselves may be effective therapeutic targets for histiocytic diseases. Additionally, further analysis of the pathways regulated by these miRNAs may identify critical gene targets in HS tumorigenesis and thus increase our understanding of these malignancies and discover novel and effective therapies. Comparative studies have the potential to provide opportunities for advancement in these orphan malignancies, and in this case, improve clinical outcome in dogs and humans. Citation Format: Emmalena J. Gregory-Bryson, Maciej Parys, Matti Kiupel, Vilma Yuzbasiyan-Gurkan. Effects of inhibition of upregulated microRNAs in canine histiocytic sarcoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4383. doi:10.1158/1538-7445.AM2014-4383