Evaluation of expression profiles of hematopoietic stem cell, endothelial cell, and myeloid cell antigens in spontaneous and chemically induced hemangiosarcomas and hemangiomas in mice

Primary vascular tumors of bone: A comprehensive literature review on classification, diagnosis and treatment

Primary vascular tumors of bone are a heterogeneous group of neoplasms, ranging from benign hemangiomas to frankly malignant epithelioid hemangioendotheliomas and angiosarcomas. Over the years, their classification has been a matter of discussion, due to morphologic similarities and uncertainty regarding biologic behavior. Over the past decade, with the development of next-generation sequencing, there has been a significant improvement in the molecular characterization of these lesions. The integration of their morphologic, immunohistochemical and molecular features has led to a better stratification, with important prognostic and therapeutic implications. Nevertheless, primary vascular bone tumors still represent a challenge for medical oncologists. Given their rarity and heterogeneity, in the last few years, there has been no significant progress in medical treatment options, so further research is needed. Here we present a review of the current knowledge regarding primary vascular tumors of the bone, correlating clinicopathologic features with tumor behavior and therapeutic approaches.

Feline Oncogenomics: What Do We Know about the Genetics of Cancer in Domestic Cats?

Simple Summary

Cancer is a significant cause of suffering and death in domestic cats. In humans, an understanding of the genetics of different types of cancers has become clinically important for all aspects of patient care and forms the basis for most emerging diagnostics and therapies. The field of ‘oncogenomics’ characterises the alterations of cancer-associated genes that are found in tumours. Such a thorough understanding of the oncogenome of human tumours has only been possible due to a high-quality reference genome and an understanding of the genetic variation that can exist between people. Although a high-quality reference genome for cats has only recently been generated, investigations into understanding the genetics of feline cancers have been underway for many years, using a range of different technologies. This review summarises what is currently known of the genetics of both common and rare types of cancer in domestic cats. Drawing attention to our current understanding of the feline oncogenome will hopefully bring this topic into focus and serve as a springboard for more much-needed research into the genetics of cancer in domestic cats.

Abstract

Cancer is a significant cause of morbidity and mortality in domestic cats. In humans, an understanding of the oncogenome of different cancer types has proven critical and is deeply interwoven into all aspects of patient care, including diagnostics, prognostics and treatments through the application of targeted therapies. Investigations into understanding the genetics of feline cancers started with cytogenetics and was then expanded to studies at a gene-specific level, looking for mutations and expression level changes of genes that are commonly mutated in human cancers. Methylation studies have also been performed and together with a recently generated high-quality reference genome for cats, next-generation sequencing studies are starting to deliver results. This review summarises what is currently known of the genetics of both common and rare cancer types in cats, including lymphomas, mammary tumours, squamous cell carcinomas, soft tissue tumours, mast cell tumours, haemangiosarcomas, pulmonary carcinomas, pancreatic carcinomas and osteosarcomas. Shining a spotlight on our current understanding of the feline oncogenome will hopefully serve as a springboard for more much-needed research into the genetics of cancer in domestic cats.

Gene fusions in vascular tumors and their underlying molecular mechanisms

INTRODUCTION

The group of vascular tumors contains many different entities, and is considered difficult by pathologists, as they often have overlapping histological characteristics. Chromosomal translocations have been identified in ~20% of mesenchymal tumors and are considered the drivers of tumor formation. Many translocations have been discovered over the past decade through next-generation sequencing. This technological advancement has also revealed several recurrent gene fusions in vascular tumors.

AREAS COVERED

This review will discuss the various vascular tumors for which recurrent gene fusions have been identified. The gene fusions and the presumed molecular mechanisms underlying tumorigenesis are shown, and potential implications for targeted therapies discussed. The identification of these gene fusions in vascular tumors has improved diagnostic accuracy, especially since several of these fusions can be easily detected using surrogate immunohistochemical markers.

EXPERT OPINION

The identification of gene fusions in a subset of vascular tumors over the past decade has improved diagnostic accuracy, and has provided the pathologists with novel diagnostic tools to accurately diagnose these often difficult tumors. Moreover, the increased understanding of the underlying molecular mechanisms can guide the development of targeted therapeutic strategies.

Expression of Hematopoietic Stem and Endothelial Cell Markers in Canine Hemangiosarcoma

Several chemicals and pharmaceuticals increase the incidence of hemangiosarcomas (HSAs) in mice, but the relevance to humans is uncertain. Recently, canine HSAs were identified as a powerful tool for investigating the pathogenesis of human HSAs. To characterize the cellular phenotype of canine HSAs, we evaluated immunoreactivity and/or messenger RNA (mRNA) expression of markers for hematopoietic stem cells (HSCs), endothelial cells (ECs), a tumor suppressor protein, and a myeloid marker in canine HSAs. Neoplastic canine cells expressed EC markers and a myeloid marker, but expressed HSC markers less consistently. The canine tumor expression results were then compared to previously published immunoreactivity results for these markers in human and mouse HSAs. There are 2 noteworthy differences across species: (1) most human HSAs had HSC marker expression, indicating that they were comprised of tumor cells that were less differentiated than those in canine and mouse tumors; and (2) human and canine HSAs expressed a late-stage EC maturation marker, whereas mouse HSAs were negative, suggesting that human and canine tumors may retain greater differentiation potential than mouse tumors. These results indicate that HSA development is variable across species and that caution is necessary when discussing translation of carcinogenic risk from animal models to humans.

Potent and PPARα-independent anti-proliferative action of the hypolipidemic drug fenofibrate in VEGF-dependent angiosarcomas in vitro

Angiosarcomas are highly aggressive tumors of endothelial origin, which carry a poor prognosis. Fenofibrate is a hypolipidemic drug, which acts by activating the transcription factor PPARα. It has also been widely reported to have ‘anti-cancer’ activity. The current study investigated its effect in a murine VEGF-dependent angiosarcoma cell-line, MS1 VEGF. The study utilised assays to monitor cell proliferation and viability, apoptosis, cell cycle progression, mitochondrial membrane potential, changes in protein expression, and changes in miRNA expression using microarrays. Fenofibrate showed potent anti-proliferative action in MS1 VEGF angiosarcoma cells, without inducing apoptosis. It enriched cells in G2/M cell cycle phase and hyperpolarised mitochondria. Other PPARα activators failed to mimic fenofibrate action. Inhibitors of PPARα and NFκB failed to reverse the inhibitory effect of fenofibrate and their combination with fenofibrate was cytotoxic. Fenofibrate downregulated the expression of key VEGF-effector proteins, including Akt, ERK, Bcl-2 and survivin, and a chemical inhibitor screen discovered relevance of these proteins to cell proliferation. A miRNA microarray revealed that fenofibrate differentially regulated cellular miRNAs with known roles in cancer and angiogenesis. The data raise the possibility that fenofibrate could be useful in angiosarcoma therapy, especially considering its well-established clinical safety and tolerability profile.

Vascular Tumors of Bone: The Evolvement of a Classification Based on Molecular Developments

The classification of vascular tumors of bone has been under debate over time. Vascular tumors in bone are rare, display highly overlapping morphology, and, therefore, are considered difficult by pathologists. Compared with their soft tissue counterparts, they are more often multifocal and sometimes behave more aggressively. Over the past decade, with the advent of next-generation sequencing, recurrent molecular alterations have been found in some of the entities. The integration of morphology and molecular changes has led to a better characterization of these separate entities.

Long bones, a slaughterhouse by-product, may serve as an excellent source for mesenchymal stem cells

Mesenchymal stem cells (MSCs) are one of the rarest sub-populations of bone marrow resident cells having inherent ability to differentiate into mesenchyme tissues e.g. bone, cartilage and adipose tissues. The natural selfrenewal ability and potential for lineage specific differentiation have made these cells an excellent material for research and therapy in regenerative medicine. But, successful isolation and in vitro expansion of these cells still remain the pivotal steps for majority of stem cell based applications. Various techniques have been successfully used for isolation of MSCs from laboratory animals, but those are difficult to apply for domestic species. Hence, harvesting MSCs from most domestic animals remains a real challenge. Here we have demonstrated an easy, convenient, low cost method of MSCs isolation from slaughtered animals. As a proof of concept, MSCs were isolated from bone marrow of 3 different species, namely, sheep, pig and goat. These cells expressed multiple markers and also retained their self-renewal potential, exhibited by successful sub-culturing over 30 passages. Moreover, MSCs expressed many pluripotency factors e.g. OCT4, Nanog, c-Myc, KLF2 and KLF4. This indicated that the bone marrow derived MSCs were at very early stage of commitment and therefore, possibly retained high plasticity. Since these cells are available from slaughtered animals, this circumvents the bioethical issues associated with invasive method of MSC isolation from bone marrow. This invaluable and easily adoptable method for isolation of MSCs from large domestic animal would encourage isolation process in other animals and help in future cell based researches and therapies in the field of regenerative medicine.

Progression of Serosal Vascular Proliferative Lesions to Hemangiosarcomas in the Uterus of the 26-Week Tg.rasH2 Mice Carcinogenicity Studies

Tg.rasH2 mice are predisposed to hemangiosarcomas. Following the spleen, the uterus is the second most commonly affected organ in the female mice. Female mice are also predisposed to spontaneous vascular proliferative lesions on the serosal surface of the uterus, in which there is proliferation of normal vessels that are lined by well-differentiated endothelial cells. The hemangiosarcomas and vascular proliferative lesions can occur independently. In our facility, we have recorded a total of 47 uterine hemangiosarcomas in 3,985 female Tg.rasH2 mice assigned to various groups in 38 studies. Of these 47 cases, we have seen 22 (46.8%) cases where there was a clear progression of the serosal uterine vascular proliferative lesion into a hemangiosarcoma. In the remaining 25 (53.2%) cases, the uterine hemangiosarcomas involved myometrium and endometrium, but there was no serosal vascular proliferation. Based on the retrospective analysis of our data, we demonstrate that the vascular proliferative lesions noted on the serosal surfaces can progress to hemangiosarcomas and therefore these vascular proliferative lesions should be considered as preneoplastic lesions.

Evaluation of potential activity of luseogliflozin on vascular proliferation in the mesenteric lymph node with or without vascular tumors in Sprague-Dawley rats in a carcinogenicity study

The incidence of mesenteric lymph node vascular tumors can vary in rats, and appropriate assessment of potential risk of tumorigenicity is needed when the incidence is higher in treated groups than in a control group. In a 2-year rat carcinogenicity study of luseogliflozin, a selective sodium-dependent glucose co-transporter 2 inhibitor for the treatment of type 2 diabetes mellitus, there was a slight but statistically significant increase in the total number of hemangiomas and hemangiosarcomas in the mesenteric lymph nodes in males at a high-dose. As part of the risk assessment for luseogliflozin, its effect on the vascular proliferation potential in the mesenteric lymph nodes was examined in a rat carcinogenicity study by performing an image analysis using specimens with double immunohistochemical staining for PCNA and CD34 in control and high-dose males. In addition, immunohistochemical staining for VEGF was performed to detect enhanced angiogenesis. In the high-dose males that did not have a hemangioma/hemangiosarcoma, neither an increased number of PCNA/CD34-positive cells nor changes in the expression pattern of VEGF was observed. On the other hand, in the high-dose males that had a hemangioma/hemangiosarcoma, the number of PCNA-positive cells was increased in the tumor areas, and the number in the hemangioma/hemangiosarcoma was approximately one-half of that in the hemangiosarcoma in the control male. In conclusion, no potential change leading to vascular proliferation/tumors was detected in the mesenteric lymph nodes of high-dose males receiving luseogliflozin.

Fat-associated lymphoid cluster in Cyprinus carpio: Characterisation and its relation with peritoneal haemangiosarcoma

FALC cells are natural helper cells producing Th2-type cytokines, which express c-kit, Sca-1, IL7R and CD45 in mouse and human. These cells are involved in allergic responses and contribute to the inflammatory reactions of adipose tissue; however, a lack of information prevails about the presence of these cells in other species. The aim of the study was to identify and characterise FALC cells in the common carp (Cyprinus carpio) using immunohistochemistry and molecular biology techniques as well as to explore their relationships with their microenvironment. Histological description of the FALC was performed using H&E and polyclonal antibodies were used against cell-surface markers such as c-kit, Sca-1 and CD45. Furthermore, gene expression of c-kit, Sca-1 and IL7R was assessed. C. carpio FALC cells express the same surface markers reported in FALC of the mouse at both the pre- and post-transcriptional level. By exposure to the soluble fraction of helminths, FALC cells produce abundant Th2 cytokines (IL-5, IL-6 and IL-13) but do not synthesise IL-1α. Additionally, FALC cells probably participate in vascular remodelling of the intestine vessels, inducing tumours because a malignant haemangiosarcoma in the peritoneal cavity was found. In this tumour, abundant FALC with their characteristic cell-surface markers were detected. The findings of this study suggest the involvement of some proto-oncogenes such as c-kit and Sca-1, and the deregulation of Src kinases modulated by CD45 present in C. carpio FALC with the ontogeny of peritoneal haemangiosarcoma in this fish species.

Nonclinical Safety of the Sodium-Glucose Cotransporter 2 Inhibitor Empagliflozin

Empagliflozin, a selective inhibitor of the renal tubular sodium-glucose cotransporter 2, was developed for treatment of type 2 diabetes mellitus. Nonclinical safety of empagliflozin was studied in a battery of tests to support global market authorization. Safety pharmacology studies indicated no effect of empagliflozin on measures of respiratory or central nervous system function in rats or cardiovascular safety in telemeterized dogs. In CD-1 mouse, Wistar Han rat, or beagle dogs up to 13, 26, or 52 weeks of treatment, respectively, empagliflozin exhibited a toxicity profile consistent with secondary supratherapeutic pharmacology related to glucose loss and included decreased body weight and body fat, increased food consumption, diarrhea, dehydration, decreased serum glucose and increases in other serum parameters reflective of increased protein catabolism, gluconeogenesis, and electrolyte imbalances, and urinary changes such as polyuria and glucosuria. Microscopic changes were consistently observed in kidney and included tubular nephropathy and interstitial nephritis (dog), renal mineralization (rat) and tubular epithelial cell karyomegaly, single cell necrosis, cystic hyperplasia, and hypertrophy (mouse). Empagliflozin was not genotoxic. Empagliflozin was not carcinogenic in female mice or female rats. Renal adenoma and carcinoma were induced in male mice only at exposures 45 times the maximum clinical dose. These tumors were associated with a spectrum of nonneoplastic changes suggestive of a nongenotoxic, cytotoxic, and cellular proliferation-driven mechanism. In male rats, testicular interstitial cell tumors and hemangiomas of the mesenteric lymph node were observed; both tumors are common in rats and are unlikely to be relevant to humans. These studies demonstrate the nonclinical safety of empagliflozin.

Identification of three molecular and functional subtypes in canine hemangiosarcoma through gene expression profiling and progenitor cell characterization

Canine hemangiosarcomas have been ascribed to an endothelial origin based on histologic appearance; however, recent findings suggest that these tumors may arise instead from hematopoietic progenitor cells. To clarify this ontogenetic dilemma, we used genome-wide expression profiling of primary hemangiosarcomas and identified three distinct tumor subtypes associated with angiogenesis (group 1), inflammation (group 2), and adipogenesis (group 3). Based on these findings, we hypothesized that a common progenitor may differentiate into the three tumor subtypes observed in our gene profiling experiment. To investigate this possibility, we cultured hemangiosarcoma cell lines under normal and sphere-forming culture conditions to enrich for tumor cell progenitors. Cells from sphere-forming cultures displayed a robust self-renewal capacity and exhibited genotypic, phenotypic, and functional properties consistent with each of the three molecular subtypes seen in primary tumors, including expression of endothelial progenitor cell (CD133 and CD34) and endothelial cell (CD105, CD146, and αvβ3 integrin) markers, expression of early hematopoietic (CD133, CD117, and CD34) and myeloid (CD115 and CD14) differentiation markers in parallel with increased phagocytic capacity, and acquisition of adipogenic potential. Collectively, these results suggest that canine hemangiosarcomas arise from multipotent progenitors that differentiate into distinct subtypes. Improved understanding of the mechanisms that determine the molecular and phenotypic differentiation of tumor cells in vivo could change paradigms regarding the origin and progression of endothelial sarcomas.

Nitroglycerine-induced nitrate tolerance compromises propofol protection of the endothelial cells against TNF-α: the role of PKC-β2 and NADPH oxidase

Continuous treatment with organic nitrates causes nitrate tolerance and endothelial dysfunction, which is involved with protein kinase C (PKC) signal pathway and NADPH oxidase activation. We determined whether chronic administration with nitroglycerine compromises the protective effects of propofol against tumor necrosis factor (TNF-) induced toxicity in endothelial cells by PKC-β₂ dependent NADPH oxidase activation. Primary cultured human umbilical vein endothelial cells were either treated or untreated with TNF-α (40 ng/mL) alone or in the presence of the specific PKC-β₂ inhibitor CGP53353 (1 μM)), nitroglycerine (10 μM), propofol (100 μM), propofol plus nitroglycerin, or CGP53353 plus nitroglycerine, respectively, for 24 hours. TNF-α increased the levels of superoxide, Nox (nitrate and nitrite), malondialdehyde, and nitrotyrosine production, accompanied by increased protein expression of p-PKC-β₂, gP91phox, and endothelial cell apoptosis, whereas all these changes were further enhanced by nitroglycerine. CGP53353 and propofol, respectively, reduced TNF-α induced oxidative stress and cell toxicity. CGP53353 completely prevented TNF-α induced oxidative stress and cell toxicity in the presence or absence of nitroglycerine, while the protective effects of propofol were neutralized by nitroglycerine. It is concluded that nitroglycerine comprises the protective effects of propofol against TNF-α stimulation in endothelial cells, primarily through PKC-β₂ dependent NADPH oxidase activation.