Heat shock proteins in canine transmissible venereal tumor

Canine Transmissible Venereal Tumor: An Infectious Neoplasia in Dogs

Canine transmissible venereal tumor is the oldest cancer in dogs and is transplanted via viable cancer cells. This cancer has a specific host, easy transmission, noticeable gross lesions, a predictable growth pattern, an immunologic relative host response, unique molecular characteristics, and is responsive to chemotherapeutic treatment. These points make researchers and practitioners interested in this cancer. Genital cases are noticeable and therefore easier to diagnose and treat than extragenital cases. By contrasting the anatomical features of the two types of cases, we highlight the uniqueness of canine transmissible venereal tumors and discuss the diagnosis, treatment, and prevention of this ancient cancer.

7Hsp70 serum levels in pet dogs-a potential diagnostic biomarker for spontaneous round cell tumors

The concentration of circulating heat shock protein 70 (Hsp70) was measured in liquid biopsies of canine tumor patients as a potential biomarker. Compared with rodent tumor models, spontaneously occurring tumors in pet dogs reflect the clinical situation of human patients better, as dogs cohabitate with their owners in the same environment, reach a much older age than rodents, can provide blood samples much more frequently, and receive up-to-date medical care and, similar to humans, their tumors show a high genetic heterogeneity. Due to the species-specific sequence homology of human and canine Hsp70, two human enzyme-linked immunosorbent assay (ELISA) systems (R&D and lipHsp70) were used to measure canine Hsp70 concentrations in serum and plasma. In general, higher Hsp70 concentrations were found in serum compared with plasma samples of dogs, and the lipHsp70 ELISA detected higher peak concentrations of Hsp70 in a broader range than the R&D ELISA. Compared with a tumor-free control group, serum Hsp70 concentrations were higher in tumor-bearing dogs, irrespective of breed, age, body weight, and gender. A sub-classification of the different tumors according to their cytological characteristics revealed significantly elevated Hsp70 serum concentrations in dogs with round cell tumors (p < 0.01), a heterogeneous group of malignancies with hematopoietic origin such as mast cells, plasma cells, lymphocytes, histiocytes, and melanomas. Future studies with larger patient cohorts and well-defined tumor sizes are necessary to elucidate the role of serum Hsp70 as a biomarker for tumor detection and monitoring of outcome in pet animals.

Expression Profiling of Hspb1 and Tp53 Genes through RT-qPCR in Different Cancer Types of Canis familiaris

Background: Diagnostic molecular marker studies are in vogue to have insight of most prevalent animal diseases including cancer. Objectives: Gene expression profiling of pro and anti-apoptotic genes was conducted in dog Lymphoma, CTVT, SCC, granuloma, perianal adenocarcinoma and mammary tumors. Materials and Methods: Cancerous tissues of 21 affected animals were obtained. Total RNA was extracted followed by cDNA synthesis. Comparative Ct method via Taqman assay (RT-qPCR) was used to quantify corresponding mRNA molecules, Tp53 and Hspb1, as normalized by GAPDH as the reference gene . Results:Hspb1 showed ectopic expression in lymphoma, CTVT and mammary tumors; its down-regulation was observed in granuloma and oral SCC with fold difference (FD) of ±35. Similarly, Tp53 as the tumor suppressor gene with pro-apoptotic properties, showed up-regulation in all tumor types, notably 80% of mammary tumors and 60% of CTVT. The FD values were 33.31 and 2.27, respectively. Conclusion: Altered transcriptomic response of Hspb1 and Tp53 was observed in all cancer types of Canis familiaris. The resulting profile depicts the involvement of the genes in cancer pathways. Thus, the data might be helpful for diagnosis, prognosis, identification and classification of these widespread neoplasms in this species.

Canine heat shock protein 27 promotes proliferation, migration, and doxorubicin resistance in the canine cell line DTK-F

Canine mammary tumors (CMTs) are the most common type of tumors in female dogs. Heat shock proteins are highly expressed in many cancers and are involved in tumor progression and chemoresistance in CMTs; however, the biological role of canine heat shock protein 27 (cHSP27) in CMTs has not been thoroughly characterized. This study investigated the roles of cHSP27 in cell growth, migration, anchorage, and resistance to doxorubicin (DOX) using DTK-F cells, a CMT cell line that does not express cHSP27. DTK-F cells were transfected with cHSP27 and stable overexpression was established. A mouse monoclonal antibody against cHSP27 was also produced. The biological functions of cHSP27 in DTK-F cells were then evaluated using a variety of assays. Overexpression of cHSP27 was associated with increased cell proliferation, clone formation, migration, and decreased DOX sensitivity. In conclusion, these data provide evidence that cHSP27 overexpression can promote anchorage-independent growth, migration, and increased DOX resistance in CMT cells.

Heat shock proteins: a therapeutic target worth to consider

Heat shock proteins (HSPs) are the molecular chaperones, that are not only expressed during the normal growth process of cell cycle consecutively, but also get induced in cells during various stress conditions produced by cellular insult, environmental changes, temperature, infections, tumors etc. According to their molecular weight and functions, HSPs are divided into five major families. HSP90, HSP70, HSP60 and HSP100 are the most studied members of the family. Experimental studies have proved that overexpression and/or inhibition of HSPs play an important role in maintaining the tolerance and cell viability under above-described stress conditions. HSP90 is found to be a promising the candidate for the diagnosis, prognosis and treatment of cancer. Similarly, HSP70, HSP60 and small HSPs experimentally and clinically have potential for the treatment of neurodegenerative disease, ischemia, cell death, autoimmunity, graft rejection, etc. In a way, exploring, the cytoprotective and immunoregulatory role of HSPs can open a new avenue for the drug discovery and treatment of critical diseases.

Heat shock protein expression analysis in canine osteosarcoma reveals HSP60 as a potentially relevant therapeutic target

Heat shock proteins (HSP) are highly conserved across eukaryotic and prokaryotic species. These proteins play a role in response to cellular stressors, protecting cells from damage and facilitating recovery. In tumor cells, HSPs can have cytoprotective effects and interfere with apoptotic cascades. This study was performed to assess the prognostic and predictive values of the gene expression of HSP family members in canine osteosarcoma (OS) and their potential for targeted therapy. Gene expressions for HSP were assessed using quantitative PCR (qPCR) on 58 snap-frozen primary canine OS tumors and related to clinic-pathological parameters. A significant increased expression of HSP60 was found in relation to shorter overall survival and an osteoblastic phenotype. Therefore, the function of HSP60 was investigated in more detail. Immunohistochemical analysis revealed heterogeneous staining for HSP60 in tumors. The highest immunoreactivity was found in tumors of short surviving dogs. Next HSP expression was shown in a variety of canine and human OS cell lines by qPCR and Western blot. In two highly metastatic cell lines HSP60 expression was silenced using siRNA resulting in decreased cell proliferation and induction of apoptosis in both cell lines. It is concluded that overexpression of HSP60 is associated with a poor prognosis of OS and should be evaluated as a new target for therapy.

Clonally transmissible cancers in dogs and Tasmanian devils

Tasmanian devil facial tumor disease (DFTD) and canine transmissible venereal tumor (CTVT) are the only known naturally occurring clonally transmissible cancers. These cancers are transmitted by the physical transfer of viable tumor cells that can be transplanted across histocompatibility barriers into unrelated hosts. Despite their common etiology, DFTD and CTVT have evolved independently and have unique life histories and host adaptations. DFTD is a recently emerged aggressive facial tumor that is threatening the Tasmanian devil with extinction. CTVT is a sexually transmitted tumor of dogs that has a worldwide distribution and that probably arose thousands of years ago. By contrasting the biology, molecular genetics and immunology of these two unusual cancers, I highlight the common and unique features of clonally transmissible cancers, and discuss the implications of clonally transmissible cancers for host-pathogen evolution.

A potential role for Helicobacter pylori heat shock protein 60 in gastric tumorigenesis

Helicobacter pylori has been found to promote the malignant process leading to gastric cancer. Heat shock protein 60 of H. pylori (HpHSP60) was previously been identified as a potent immunogene. This study investigates the role of HpHSP60 in gastric cancer carcinogenesis. The effect of HpHSP60 on cell proliferation, anti-death activity, angiogenesis and cell migration were explored. The results showed that HpHSP60 enhanced migration by gastric cancer cells and promoted tube formation by umbilical vein endothelial cells (HUVECs); however, HpHSP60 did not increase cell proliferation nor was this protein able to rescue gastric cancer cells from death. Moreover, the results also indicated HpHSP60 had different effects on AGS gastric cancer cells or THP-1 monocytic cells in terms of their expression of pro-inflammatory cytokines, which are known to be important to cancer development. We propose that HpHSP60 may trigger the initiation of carcinogenesis by inducing pro-inflammatory cytokine release and by promoting angiogenesis and metastasis. Thus, this extracellular pathogen-derived HSP60 is potentially a vigorous virulence factor that can act as a carcinogen during gastric tumorigenesis.

Electroporation-mediated IL-12 gene therapy in a transplantable canine cancer model

Interleukin-12 (IL-12) is effective in treating many types of rodent tumors, but has been unsuccessful in most human clinical trials, suggesting that animal models of more clinical relevance are required for evaluating human cancer immunotherapy. Herein, we report on the effectiveness of gene therapy with plasmid encoding human IL-12 (pIL-12) through in vivo electroporation in the treatment of beagles with a canine tumor, the canine transmissible venereal tumor (CTVT). The optimal electroporation conditions for gene transfer into CTVTs were tested by luciferase activity and determined to be a voltage of 200 V and duration of 50 msec, with the number of shocks set at 10 pulses, and the use of an electrode with 2 needles. Under these conditions, intratumoral administration of as little as 0.1 mg pIL-12 followed by electroporation significantly inhibited the growth of well-established tumors and eventually led to complete tumor regression. Furthermore, local pIL-12 treatment also induced a strong systemic effect that prevented new tumor growth and cured established tumors at distant locations. Intratumoral administration of pIL-12 greatly elevated the IL-12 level in the tumor masses, but produced only a trace amount in the serum. A high level of IFN-gamma mRNA was also detected in the treated tumor masses. pIL-12 gene therapy attracted significantly more lymphocytes infiltrating the tumors, including CD4(+) and CD8(+) T cells, and the surface expression of MHC I and MHC II molecules on CTVT cells was greatly increased after pIL-12 therapy. This treatment also induced apoptosis of the tumor cells as detected by Annexin V. More importantly, delivery of pIL-12 with intratumoral electroporation did not result in any detectable toxicity in the dogs. We conclude that intratumoral electroporation of the pIL-12 gene could cause profound immunologic host responses and efficiently treat CTVT in beagle dogs. The results also indicate that CTVT is an excellent large animal cancer model for testing immunogene therapies mediated by electroporation.

Heat shock proteins in animal neoplasms and human tumours--a comparison

Heat shock proteins (HSPs) are implicated in all phases of cancer from proliferation, impaired apoptosis and sustained angiogenesis to invasion and metastasis. The presence of abnormal HSP levels in several human tumours suggests that these proteins could be used as diagnostic and/or prognostic markers, whilst the direct correlation between HSP expression and drug resistance in neoplastic tissues means they could also be used to predict cancer response to specific treatment. HSPs have also been successfully targeted in clinical trials modifying their expression or chaperone activity. Preliminary studies in veterinary medicine have also demonstrated the presence of altered HSP expression in neoplasms, and the study of carcinogenesis and the role of HSPs in animal models will surely be an additional source of information for clinical cancer research.

Apoptosis in the transplanted canine transmissible venereal tumor during growth and regression phases

Twelve male, mongrel, adult dogs were subcutaneously transplanted with cells originated from two canine transmissible venereal tumors (TVT). The aim was to demonstrate and to quantify the occurrence of apoptosis in the TVT regression. After six months of transplantation, a tumor sample was obtained from each dog, being six dogs with TVT in the growing phase and six in the regression phase as verified by daily measurements. Samples were processed for histological and ultrastructural purposes as well as for DNA extraction. Sections of 4µm were stained by HE, Shorr, methyl green pyronine, Van Gieson, TUNEL reaction and immunostained for P53. The Shorr stained sections went through morphometry that demonstrated an increase of the apoptotic cells per field in the regressive tumors. It was also confirmed by transmission electron microscopy, which showed cells with typical morphology of apoptosis and by the TUNEL reaction that detected in situ the 3'OH nick end labeling mainly in the regressive tumors. The regressive TVTs also showed an intensified immunostaining for P53 besides a more intense genomic DNA fragmentation detected by the agarose gel electrophoresis. In conclusion, apoptosis has an important role in the regression of the experimental TVT in a way that is P53-dependent.

Identification of canine transmissible venereal tumor cells using in situ polymerase chain reaction and the stable sequence of the long interspersed nuclear element

Canine transmissible venereal tumor (CTVT) is a unique tumor that can be transplanted across the major histocompatibility complex (MHC) barrier by viable tumor cells. In dogs, CTVT grows progressively for a few months and then usually regresses spontaneously. A long interspersed nuclear element (LINE) insertion is found specifically and constantly in the 5' end of the CTVT cell c-myc gene, outside the first exon. The rearranged LINE-c-myc gene sequence has been used with polymerase chain reaction (PCR) to diagnose CTVT. However, in CTVT cells, the total length of the inserted LINE gene is not constant. In this experiment, variation in the inserted LINE gene was studied to determine which parts of the LINE sequence can be used as primers to identify CTVT cells with in situ PCR (IS PCR). The LINE gene was inserted between the TATA boxes in the promoter region of c-myc. In CTVT cells, deletions of different lengths are frequent in this gene. However, the 550-bp segment at the 5' end of the LINE-c-myc gene was stable. Thus, primers were designed to cover the stable 0.55-kb segment from the 5' end outside the first exon of the c-myc gene to the 5' end of LINE gene stable segment. With these primers and IS PCR, individual CTVT cells in formalin-fixed tissue sections and CTVT cultures were identified. Cells from other canine tumors were negative for this gene. In addition, the CTVT-specific, 0.55-kb segment was not found in any spindle-shaped cells from progressive or regressive phase CTVT. The IS PCR technique also did not detect any positive spindle-shaped cells in CTVT cell cultures. Thus, fibroblastic terminal differentiation is less likely to be a mechanism for spontaneous regression of CTVT cells.

Canine transmissible venereal tumour: Cytogenetic origin, immunophenotype, and immunobiology. A review

Canine transmissible venereal tumour (CTVT) is the only known naturally occurring tumour that can be transplanted as an allograft across major histocompatibility (MHC) barriers within the same species, and even to other members of the canine family, such as foxes, coyotes and wolves. The progression of this tumour is unique in that, it follows a predictable growth pattern. In natural and experimental cases, the growth pattern includes progressive growth phase, static phase and regression phase, and this is followed by transplantation immunity in immunocompetent adults, while metastasis occurs in puppies and immunosuppressed dogs. Because of the uniqueness of CTVT transmission and progression, experimental investigations of various aspects of the biology of CTVT have been used to provide clues to the immunobiology of both animal and human tumours. This review examines the current state of knowledge of the aspects of the cytogenetic origin, immunophenotype, immunobiology and immunotherapy of CTVT.