What do we know about canine osteosarcoma treatment? Review

Immunohistochemical Investigation into Protein Expression Patterns of FOXO4, IRF8 and LEF1 in Canine Osteosarcoma

Osteosarcoma (OSA) is the most common type of primary bone malignancy in people and dogs. Our previous molecular comparisons of canine OSA against healthy bone resulted in the identification of differentially expressed protein-expressing genes (forkhead box protein O4 (FOXO4), interferon regulatory factor 8 (IRF8), and lymphoid enhancer binding factor 1 (LEF1)). Immunohistochemistry (IHC) and H-scoring provided semi-quantitative assessment of nuclear and cytoplasmic staining alongside qualitative data to contextualise staining (n = 26 patients). FOXO4 was expressed predominantly in the cytoplasm with significantly lower nuclear H-scores. IRF8 H-scores ranged from 0 to 3 throughout the cohort in the nucleus and cytoplasm. LEF1 was expressed in all patients with significantly lower cytoplasmic staining compared to nuclear. No sex or anatomical location differences were observed. While reduced levels of FOXO4 might indicate malignancy, the weak or absent protein expression limits its primary use as diagnostic tumour marker. IRF8 and LEF1 have more potential for prognostic and diagnostic uses and facilitate further understanding of their roles within their respective molecular pathways, including Wnt/beta-catenin/LEF1 signalling and differential regulation of tumour suppressor genes. Deeper understanding of the mechanisms involved in OSA are essential contributions towards the development of novel diagnostic, prognostic, and treatment options in human and veterinary medicine contexts.

Ancient Diseases in Vertebrates: Tumours through the Ages

Paleo-oncology studies neoplastic diseases in fossilised animals, including human remains. Recent advancements have enabled more accurate diagnoses of ancient pathologies despite the inherent challenges in identifying tumours in fossils-such as the rarity of well-preserved specimens, the predominance of bone remains, and the difficulty in distinguishing neoplastic from non-neoplastic lesions. This study compiles reports of tumours in fossilised animals, highlighting that neoplasms are present in a wide range of vertebrates and drawing comparisons to modern instances of similar diseases. The findings underscore the multifactorial aetiology of tumours, which involves genetic, environmental, and lifestyle factors, and suggest that tumours have been around for at least 350 million years.

Pilot Clinical Trial to Evaluate In Situ Calcium Phosphate Cement Injection for Conservative Surgical Management of Appendicular Osteosarcoma in Dogs

Cementoplasty is a minimally invasive procedure that consists of injecting a bone substitute into the tumor lesion to provide bone reinforcement and alleviate pain. This study aimed to demonstrate the feasibility, safety, and efficacy of cementoplasty with a calcium phosphate cement in osteosarcoma to reduce pain and preserve limb function. Throughout the 6-month study, dogs received no adjuvant therapy, and dogs' evaluations included a clinical examination, monitoring of postoperative complications, radiographic follow-up, and assessment of limb function and pain scores. Out of 12 dogs enrolled, 10 were withdrawn before study completion due to deterioration in their general condition. Nine (9) dogs were followed until D28, six until D56, and two until D183. Compared to D0, more than 50% of the dogs showed improvement in both veterinarian and owner scores at their final visit. Throughout the study, 10 major and 4 minor complications were reported, all unrelated to the procedure. This open non-controlled study provides first evidence of the feasibility, safety, and efficacy of cementoplasty procedure using a calcium phosphate bone cement to relieve pain and preserve limb function in dogs suffering from appendicular osteosarcoma.

Proteomic Analyses Reveal the Role of Alpha-2-Macroglobulin in Canine Osteosarcoma Cell Migration

Canine osteosarcoma (OSA) is an aggressive bone neoplasia with high metastatic potential. Metastasis is the main cause of death associated with OSA, and there is no current treatment available for metastatic disease. Proteomic analyses, including matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI TOF/TOF MS), are widely used to select molecular targets and identify proteins that may play a key role in primary tumours and at various steps of the metastatic cascade. The main aim of this study was to identify proteins differently expressed in canine OSA cell lines with different malignancy phenotypes (OSCA-8 and OSCA-32) compared to canine osteoblasts (CnOb). The intermediate aim of the study was to compare canine OSA cell migration capacity and assess its correlation with the malignancy phenotypes of each cell line. Using MALDI-TOF/TOF MS analyses, we identified eight proteins that were significantly differentially expressed (p ≤ 0.05) in canine OSA cell lines compared to CnOb: cilia- and flagella-associated protein 298 (CFAP298), general transcription factor II-I (GTF2I), mirror-image polydactyly gene 1 protein (MIPOL1), alpha-2 macroglobulin (A2M), phosphoglycerate mutase 1 (PGAM1), ubiquitin (UB2L6), ectodysplasin-A receptor-associated adapter protein (EDARADD), and leucine-rich-repeat-containing protein 72 (LRRC72). Using the Simple Western technique, we confirmed high A2M expression in CnOb compared to OSCA-8 and OSCA-32 cell lines (with intermediate and low A2M expression, respectively). Then, we confirmed the role of A2M in cancer cell migration by demonstrating significantly inhibited OSA cell migration by treatment with A2M (both at 10 and 30 mM concentrations after 12 and 24 h) in a wound-healing assay. This study may be the first report indicating A2M's role in OSA cell metastasis; however, further in vitro and in vivo studies are needed to confirm its possible role as an anti-metastatic agent in this malignancy.

Identification of allograft inflammatory factor-1 suppressing the progression and indicating good prognosis of osteosarcoma

BACKGROUND

Osteosarcoma is one of the most common cancers worldwide. Intense efforts have been made to elucidate the pathogeny, but the mechanisms of osteosarcoma are still not well understood. We aimed to investigate the potential biomarker, allograft inflammatory factor-1 (AIF1), affecting the progression and prognosis of osteosarcoma.

METHODS

Three microarray datasets were downloaded from GEO datasets and one was obtained from the TCGA dataset. The differentially expressed genes (DEGs) were identified. GO and KEGG functional enrichment analyses of overlapped DEGs were performed. The PPI network of overlapped DEGs was constructed by STRING and visualized with Cytoscape. Overall survival (OS) and Metastasis free survival (MFS) were analyzed from GSE21257. Finally, the effect of the most relevant core gene affecting the progression of osteosarcoma was examined in vitro.

RESULTS

One hundred twenty six DEGs were identified, consisting of 65 upregulated and 61 downregulated genes. Only AIF1 was significantly associated with OS and MFS. It was found that AIF1 could be enriched into the NF-κB signaling pathway. GSEA and ssGSEA analyses showed that AIF1 was associated with the immune invasion of tumors. Cell experiments showed that AIF1 was underexpressed in osteosarcoma cell lines, while the malignant propriety was attenuated after overexpressing the expression of AIF1. Moreover, AIF1 also affects the expression of the NF-κB pathway.

CONCLUSION

In conclusion, DEGs and hub genes identified in the present study help us understand the molecular mechanisms underlying the carcinogenesis and progression of osteosarcoma, and provide candidate targets for diagnosis and treatment of osteosarcoma.

Osteosarcoma of the wing in a sulfur-crested cockatoo

A 26-year-old female sulfur-crested cockatoo (Cacatua galerita) was evaluated for vocalizing through the night and extending her right wing. Physical examination revealed a large, firm mass extending from the humerus to the distal aspect of the elbow. Computed tomography confirmed a large aggressive mass of the right distal humerus with a large soft tissue component, severe osteolysis, and adjacent periosteal proliferation. Fine-needle aspirates of the mass were most compatible with sarcoma, and osteosarcoma was prioritized. An unstained slide was treated with nitroblue tetrazolium chloride/5-bromo-4-chloro-3-indolyl phosphate toluidine salt-phosphatase (NBT/BCIP) substrate for ALP detection and was strongly positive, confirming a diagnosis of osteosarcoma. A month later, the patient underwent wing amputation and arrested during recovery from anesthesia. Post-mortem examination and histopathology were consistent with osteosarcoma. This case report highlights a rare occurrence of osteosarcoma in a cockatoo as well as its cytologic and histologic features. Additionally, this report provides support for NBT/BCIP application in ALP-expressing tumors, a cytochemical stain that has been minimally investigated in avian species.

Applications and Potentials of a Silk Fibroin Nanoparticle Delivery System in Animal Husbandry

Silk fibroin (SF), a unique natural polymeric fibrous protein extracted from Bombyx mori cocoons, accounts for approximately 75% of the total mass of silk. It has great application prospects due to its outstanding biocompatibility, biodegradability, low immunogenicity, and mechanical stability. Additionally, it is non-toxic and environmentally friendly. Nanoparticle delivery systems constructed with SF can improve the bioavailability of the carriers, increase the loading rates, control the release behavior of the deliverables, and enhance their action efficiencies. Animal husbandry is an integral part of agriculture and plays a vital role in the development of the rural economy. However, the pillar industry experiences a lot of difficulties, like drug abuse while treating major animal diseases, and serious environmental pollution, restricting sustainable development. Interestingly, the limited use cases of silk fibroin nanoparticle (SF NP) delivery systems in animal husbandry, such as veterinary vaccines and feed additives, have shown great promise. This paper first reviews the SF NP delivery system with regard to its advantages, disadvantages, and applications. Moreover, we describe the application status and developmental prospects of SF NP delivery systems to provide theoretical references for further development in livestock production and promote the high-quality and healthy development of animal husbandry.

Establishment and Characterization of Cell Lines from Canine Metastatic Osteosarcoma

Despite the advancements in treatments for other cancers, the outcomes for osteosarcoma (OSA) patients have not improved in the past forty years, especially in metastatic patients. Moreover, the major cause of death in OSA patients is due to metastatic lesions. In the current study, we report on the establishment of three cell lines derived from metastatic canine OSA patients and their transcriptome as compared to normal canine osteoblasts. All the OSA cell lines displayed significant upregulation of genes in the epithelial mesenchymal transition (EMT) pathway, and upregulation of key cytokines such as CXCL8, CXCL10 and IL6. The two most upregulated genes are MX1 and ISG15. Interestingly, ISG15 has recently been identified as a potential therapeutic target for OSA. In addition, there is notable downregulation of cell cycle control genes, including CDKN2A, CDKN2B and THBS1. At the protein level, p16INK4A, coded by CDKN2A, was undetectable in all the canine OSA cell lines, while expression of the tumor suppressor PTEN was variable, with one cell line showing complete absence and others showing low levels of expression. In addition, the cells express a variety of actionable genes, including KIT, ERBB2, VEGF and immune checkpoint genes. These findings, similar to those reported in human OSA, point to some genes that can be used for prognosis, targeted therapies and novel drug development for both canine and human OSA patients.

Vertebral Osteosarcoma in Two Cats-Diagnosis, Treatment, and Outcome

In this case report, we describe the diagnosis, treatment, and outcome of two feline cases of vertebral osteosarcoma. Case 1: A 6-year-old female neutered domestic longhaired cat was presented with progressive paraparesis, ataxia, and spinal hyperesthesia. MRI of the thoracolumbar spinal cord and vertebral column revealed a strongly contrast-enhancing mass lesion originating from the dorsal lamina and spinous process of T13. The lesion caused extradural compression of the spinal cord. Surgical debulking was performed, and the histopathological evaluation of surgical biopsies was consistent with vertebral osteosarcoma. The cat was paraplegic with intact nociception post-surgery. Subsequently, the cat recovered ambulation while remaining mildly ataxic and paraparetic at long-term follow-up. Post-operative chemotherapy was started with doxorubicin. CT scans at 2, 4, 9, 13, and 20 months post-surgery showed no signs of local recurrence or metastasis. Case 2: A 15.5-year-old male neutered domestic shorthaired cat was presented with progressive paraparesis, tail paresis, and spinal hyperesthesia. Radiographs and CT scan of the lumbar vertebral column showed a large mass originating from the dorsal lamina and spinous process of L6, suggestive of neoplasia, with severe compression of the spinal cord. Surgical debulking was performed, and the histopathological evaluation was consistent with vertebral osteosarcoma. Post-operative chemotherapy was started with doxorubicin. Seven months post-surgery, the patient was neurologically normal with no signs of metastatic disease. This case report highlights the possibility of good outcomes after the surgical treatment of feline vertebral osteosarcoma supplemented with post-surgical chemotherapy.

PEG-liposomal doxorubicin as a potential agent for canine metastatic osteosarcoma - in vitro and ex ovo studies

Introduction

Appendicular osteosarcoma (OSA) is a highly aggressive and metastatic primary bone tumour in dogs. Standard therapy is amputation and adjuvant chemotherapy (e.g. with doxorubicin). Liposomal drug delivery may augment therapeutic efficacy and reduce negative side effects. Polyethylene glycol (PEG)-liposomal doxorubicin treats human metastatic cancers effectively. The study aimed was to evaluate PEG-liposomal doxorubicin's inhibitory effect on canine metastatic proliferation and migration in vitro. It also aimed to appraise the drug's extravasation inhibition in vivo using the human medicine-proven chick embryo chorioallantoic membrane ex ovo model.

Material and Methods

The canine D-17 OSA cell line was cultured and inoculated with decreasing concentrations of PEG-liposomal doxorubicin and conventional doxorubicin in a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) test of cell viability, proliferation and cytotoxicity. Flow cytometry with Annexin V and Draq 7 staining confirmed the MTT test results, indicating dead, early and late apoptotic, and live cells. The inhibitory effect of the two preparations on cancer cell migration was investigated with a wound-healing assay. Culture plates seeded with cells were prepared. The cell monolayer was scratched and images of cells migrating to the scratch were captured at 0 h, 12 h and 24 h. Also, embryos were removed from three-day-incubated fertilised chicken eggs. On the 12th day, labelled D-17 cells were injected into each embryo. Embryos in one group received 100 μL of phosphate-buffered saline as controls, those in another group 30 μg/mL of PEG-liposomal doxorubicin, and those in the last group 6 μg/mL of conventional doxorubicin. The effectiveness of the intravascular administration of the D-17 cells was confirmed under a microscope.

Results

PEG-liposomal doxorubicin inhibited the migration of canine OSA cells more effectively than conventional doxorubicin (P ≤ 0.05). The ex ovo model showed that both drugs had similar impacts on canine metastatic OSA.

Conclusion

The liposomal form of the drug may be considered a potentially effective compound in canine metastatic OSA; nevertheless, further in vivo studies are essential to confirm this hypothesis.

Long-term adjuvant metronomic chemotherapy in a dog with recurrent maxillofacial osteosarcoma

Osteosarcoma (OSA) is the most common malignant bone tumour in dogs; however, OSA of the maxilla is uncommon compared to appendicular OSA. Oral melanoma also commonly occurs in dogs with frequent distant metastasis. The role of adjuvant chemotherapy has been questioned in maxillary OSA and melanoma. A 17-year-old English Cocker Spaniel was referred with a growing mass on the right maxilla and a right lower lip mass. Osteosarcoma was diagnosed after partial maxillectomy, and the right lower lip mass was diagnosed as oral melanoma. Metronomic chemotherapy (MC) was performed, and the number of doses was tapered due to side effects at 5 weeks after initiation of MC. After 130 weeks of MC, chemotherapy was suspended due to kidney disease. After the suspension of chemotherapy, findings suggesting recurrence and metastasis were detected. The dog suddenly died 193 weeks after surgery, which was 8-14 times longer than the expected survival time. To the best of our knowledge, this is the first case report of successful long-term combination therapy, including surgery and MC, in a dog with maxillary OSA and lip melanoma. Our results show that the survival time can be greatly extended if MC is performed with proper management.

Case report: Limb-sparing surgery of tibial chondrosarcoma with frozen autologous bone graft using liquid nitrogen in a dog

Chondrosarcoma is the second most common primary bone tumor after osteosarcoma in dogs. Chondrosarcoma has a good prognosis owing to its low metastatic rate and long survival time, even with amputation alone. However, amputation risks reducing the quality of life in patients with other orthopedic diseases of the non-affected limb, neurological diseases, or large body size. Limb-sparing surgery with frozen autologous bone grafting using liquid nitrogen allows bone quality to be maintained in the normal bone area while killing tumor cells, thereby preserving the affected limb. Thus, it is expected to maintain the quality of life. We describe herein limb-sparing surgery for tibial chondrosarcoma with frozen autologous bone graft using liquid nitrogen in an 8-year and 8-month-old castrated male bulldog weighing 29.2 kg. The patient had chondrosarcoma of the left tibia, suspected cranial cruciate ligament rupture of the right stifle, and degenerative lumbosacral stenosis. In such a case, amputation would increase the burden on the non-affected limb or spine, which could cause difficulty in walking; therefore, we performed limb-sparing surgery. Postoperatively, although a circumduction gait associated with stifle arthrodesis remained, the patient maintained the quality of life for 20 months, and the owner was satisfied with the results.

Isolation and Characterization of Novel Canine Osteosarcoma Cell Lines from Chemotherapy-Naïve Patients

The present study aimed to establish novel canine osteosarcoma cell lines (COS3600, COS3600B, COS4074) and characterize the recently described COS4288 cells. The established D-17 cell line served as a reference. Analyzed cell lines differed notably in their biological characteristics. Calculated doubling times were between 22 h for COS3600B and 426 h for COS4074 cells. COS3600B and COS4288 cells produced visible colonies after anchorage-independent growth in soft agar. COS4288 cells were identified as cells with the highest migratory capacity. All cells displayed the ability to invade through an artificial basement membrane matrix. Immunohistochemical analyses revealed the mesenchymal origin of all COS cell lines as well as positive staining for the osteosarcoma-relevant proteins alkaline phosphatase and karyopherin α2. Expression of p53 was confirmed in all tested cell lines. Gene expression analyses of selected genes linked to cellular immune checkpoints (CD270, CD274, CD276), kinase activity (MET, ERBB2), and metastatic potential (MMP-2, MMP-9) as well as selected long non-coding RNA (MALAT1) and microRNAs (miR-9, miR-34a, miR-93) are provided. All tested cell lines were able to grow as multicellular spheroids. In all spheroids except COS4288, calcium deposition was detected by von Kossa staining. We believe that these new cell lines serve as useful biological models for future studies.

Defucosylated Mouse-Dog Chimeric Anti-Human Epidermal Growth Factor Receptor 2 Monoclonal Antibody (H77Bf) Exerts Antitumor Activities in Mouse Xenograft Models of Canine Osteosarcoma

Human epidermal growth factor receptor 2 (HER2) has been studied in many human cancer types, and its overexpression and/or gene mutation contribute to the poor prognosis. Therefore, HER2 is an important therapeutic target in various cancer types, including breast and gastric cancers. We previously developed an anti-HER2 monoclonal antibody (mAb), H₂Mab-77 (mouse IgG₁, kappa), which detects HER2 and dog HER2 (dHER2) with high sensitivity and specificity. In this study, we produced a defucosylated mouse-dog chimeric anti-HER2 mAb (H77Bf), and investigated the reactivity against canine osteosarcoma D-17 cells by flow cytometry. Furthermore, we showed that H77Bf exerted antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity against D-17 cells in vitro and exhibited the potent antitumor activity in vivo. These results suggest that H77Bf exerts antitumor effects against dHER2-expressing canine tumors and could be valuable as part of an antibody treatment regimen for them.

Sorafenib and Doxorubicin Show Synergistic Effects in Human and Canine Osteosarcoma Cell Lines

Osteosarcoma (OSA) is the most common bone tumor in both humans and dogs and has a nearly ten-fold higher incidence in dogs than humans. Despite advances in the treatment of other cancers, the overall survival rates for OSA have stagnated for the past four decades. Therefore, there is a great need to identify novel and effective treatments. We screened a series of tyrosine kinase inhibitors and selected sorafenib, a multi-kinase inhibitor, for further evaluation alone and in combination with cisplatin, carboplatin, and doxorubicin on canine and human OSA cell lines. Our data point to synergistic effects when sorafenib is combined with doxorubicin, but not when combined with cisplatin or carboplatin, in both human and canine OSA. Based on current findings, clinical trials using a combination of doxorubicin and sorafenib in proof-of-concept studies in dogs are warranted. These studies can be carried out relatively quickly in dogs where case load is high and, in turn, provide useful data for the initiation of clinical trials in humans.

Doxorubicin-Loaded Lipid Nanoparticles Coated with Calcium Phosphate as a Potential Tool in Human and Canine Osteosarcoma Therapy

Osteosarcoma (OSA) is the most frequently diagnosed primary malignant bone tumor in humans and dogs. In both species, standard chemotherapy can be limited by multidrug resistance of neoplastic cells, which prevents intracellular accumulation of cytotoxic drugs, resulting in chemotherapy failure. In this study, a lipophilic ester of doxorubicin (C12DOXO) was loaded into nanoparticles (NPs) using the “cold microemulsion dilution” method. The resulting NPs were then coated with calcium phosphate (CaP) in two different ways to have calcium or phosphate ions externally exposed on the surface. These systems were characterized by determining mean diameter, zeta potential, and drug entrapment efficiency; afterward, they were tested on human and canine OSA cells to study the role that the coating might play in increasing both drug uptake into tumor cells and cytotoxicity. Mean diameter of the developed NPs was in the 200–300 nm range, zeta potential depended on the coating type, and C12DOXO entrapment efficiency was in the 60–75% range. Results of studies on human and canine OSA cells were very similar and showed an increase in drug uptake and cytotoxicity for CaP-coated NPs, especially when calcium ions were externally exposed. Therefore, applications in both human and veterinary medicine can be planned in the near future.

Inhaled recombinant human IL-15 in dogs with naturally occurring pulmonary metastases from osteosarcoma or melanoma: a phase 1 study of clinical activity and correlates of response

PURPOSE

Although recombinant human interleukin-15 (rhIL-15) has generated much excitement as an immunotherapeutic agent for cancer, activity in human clinical trials has been modest to date, in part due to the risks of toxicity with significant dose escalation. Since pulmonary metastases are a major site of distant failure in human and dog cancers, we sought to investigate inhaled rhIL-15 in dogs with naturally occurring lung metastases from osteosarcoma (OSA) or melanoma. We hypothesized a favorable benefit/risk profile given the concentrated delivery to the lungs with decreased systemic exposure.

EXPERIMENTAL DESIGN

We performed a phase I trial of inhaled rhIL-15 in dogs with gross pulmonary metastases using a traditional 3+3 cohort design. A starting dose of 10 µg twice daily × 14 days was used based on human, non-human primate, and murine studies. Safety, dose-limiting toxicities (DLT), and maximum tolerated dose (MTD) were the primary objectives, while response rates, progression-free and overall survival (OS), and pharmacokinetic and immune correlative analyses were secondary.

RESULTS

From October 2018 to December 2020, we enrolled 21 dogs with 18 dogs reaching the 28-day response assessment to be evaluable. At dose level 5 (70 μg), we observed two DLTs, thereby establishing 50 µg twice daily × 14 days as the MTD and recommended phase 2 dose. Among 18 evaluable dogs, we observed one complete response >1 year, one partial response with resolution of multiple target lesions, and five stable disease for an overall clinical benefit rate of 39%. Plasma rhIL-15 quantitation revealed detectable and sustained rhIL-15 concentrations between 1-hour and 6 hour postnebulization. Decreased pretreatment lymphocyte counts were significantly associated with clinical benefit. Cytotoxicity assays of banked peripheral blood mononuclear cells revealed significant increases in peak cytotoxicity against canine melanoma and OSA targets that correlated with OS.

CONCLUSIONS

In this first-in-dog clinical trial of inhaled rhIL-15 in dogs with advanced metastatic disease, we observed promising clinical activity when administered as a monotherapy for only 14 days. These data have significant clinical and biological implications for both dogs and humans with refractory lung metastases and support exploration of combinatorial therapies using inhaled rhIL-15.

Expression of the hedgehog signaling pathway and the effect of inhibition at the level of Smoothened in canine osteosarcoma cell lines

Osteosarcoma (OSA) is the most common malignant bone cancer in dogs. Canine and human OSA share several features, including tumor environments, response to traditional treatment, and several molecular pathways. Hedgehog (Hh) signaling is known to contribute to tumorigenesis and progression of various cancers, including human OSA. This study aimed to identify the role of the Hh signaling pathway in canine OSA cell lines, including Abrams, D17, and Moresco, focusing on the signal transducer Smoothened (SMO). mRNA and protein levels of Hh pathway components, including SHH, IHH, SMO, and PTCH1, were aberrant in all examined OSA cell lines compared with canine osteoblast cells. The SMO inhibitor cyclopamine significantly decreased cell viability and colony-forming ability in the canine OSA cell lines in a dose-dependent manner. Moresco cells, which expressed the highest level of SMO protein, were the most sensitive to the anticancer effect of cyclopamine among the three canine OSA cell lines tested. Hh downstream target gene and protein expression in canine OSA cell lines were downregulated after cyclopamine treatment. In addition, cyclopamine significantly increased apoptotic cell death in Abrams and Moresco cells. The findings that Hh/SMO is activated in canine OSA cell lines and cyclopamine suppresses OSA cell survival via inhibition of SMO suggest that the Hh/SMO signaling pathway might be a novel therapeutic target for canine OSA. This article is protected by copyright. All rights reserved.

In Silico Modeling of the Induction of Apoptosis by Cryptotanshinone in Osteosarcoma Cell Lines

Osteosarcoma (OS) is the most common primary malignant bone tumor of both children and pet canines. Its characteristic genomic instability and complexity coupled with the dearth of knowledge about its etiology has made improvement in the current treatment difficult. We use the existing literature about the biological pathways active in OS and combine it with the current research involving natural compounds to identify new targets and design more effective drug therapies. The key components of these pathways are modeled as a Boolean network with multiple inputs and multiple outputs. The combinatorial circuit is employed to theoretically predict the efficacies of various drugs in combination with Cryptotanshinone. We show that the action of the herbal drug, Cryptotanshinone on OS cell lines induces apoptosis by increasing sensitivity to TNF-related apoptosis-inducing ligand (TRAIL) through its multi-pronged action on STAT3, DRP1 and DR5. The Boolean framework is used to detect additional drug intervention points in the pathway that could amplify the action of Cryptotanshinone.

Canine osteosarcoma cells exhibit basal accumulation of multiple chaperone proteins and are sensitive to small molecule inhibitors of GRP78 and heat shock protein function

Osteosarcoma is the most common type of bone cancer in dogs and humans, with significant numbers of patients experiencing treatment failure and disease progression. In our search for new approaches to treat osteosarcoma, we previously detected multiple chaperone proteins in the surface-exposed proteome of canine osteosarcoma cells. In the present study, we characterized expression of representative chaperones and find evidence for stress adaptation in canine osteosarcoma cells relative to osteogenic progenitors from normal bone. We compared the cytotoxic potential of direct (HA15) and putative (OSU-03012) inhibitors of Grp78 function and found canine POS and HMPOS osteosarcoma cells to be more sensitive to both compounds than normal cells. HA15 and OSU-03012 increased the thermal stability of Grp78 in intact POS cells at low micromolar concentrations, but each induced distinct patterns in Grp78 expression without significant change in Grp94. Both inhibitors were as effective alone as carboplatin and showed little evidence of synergy in combination treatment. However, HMPOS cells with acquired resistance to carboplatin were sensitive to inhibition of Grp78 (by HA15; OSU-03012), Hsp70 (by VER-155008), and Hsp90 (by 17-AAG) function. These results suggest that multiple nodes within the osteosarcoma chaperome may be relevant chemotherapeutic targets against platinum resistance.

Quercetin and Methotrexate in Combination have Anticancer Activity in Osteosarcoma Cells and Repress Oncogenic MicroRNA-223

INTRODUCTION

Osteosarcoma (OS) is one of the most common bone neoplasms in adolescents. Notable short- and long-term toxic effects of OS chemotherapy regimens have been reported. Hence, new chemotherapeutic agents with the ability to potentiate OS chemotherapy drugs and protect non-tumorous tissues are required.

METHODS

Saos-2 cells were treated with Methotrexate (MTX) and Quercetin (Que) (a polyphenolic flavonoid with anti-tumor effects) alone and in combination. MTT assay was performed to investigate the cytotoxicity of the drugs. Moreover, apoptosis-involved genes, including miR-223, p53, BCL-2, CBX7, and CYLD expression were analyzed via qRT-PCR. Annexin V-FITC/PI kit was employed to assess the apoptosis rate.

RESULTS

The MTT results showed that Que increases MTX cytotoxicity on OS cells. The measured IC50s are 142.3 µM for QUE and 13.7 ng/ml for MTX. A decline in MTX IC50 value was observed from 13.7 ng/ml to 8.45 ng/ml in the presence of Que. Moreover, the mRNA expression outcomes indicated that the combination therapy significantly up-regulates the tumor suppressor genes, such as p53, CBX7, and CYLD, and declines anti-apoptotic genes BCL-2 and miR-223, which can lead to proliferation inhibition and apoptosis inducement. Furthermore, the apoptosis rate increased significantly from 6.03% in the control group to 38.35% in Saos-2 cells that were treated with the combination of MTX and Que.

CONCLUSION

Que, with the potential to boost the anticancer activity of MTX on Saos-2 cancer cells through proliferation inhibition and apoptosis induction, is a good candidate for combination therapy.

Synergistic Antitumor Interaction of Risedronate Sodium and Standard Anticancer Agents in Canine (D-17) and Human Osteosarcoma (U-2 OS) Cell Lines

The study discusses in vitro cytotoxicity of a combination of cytostatic drugs (doxorubicin, cisplatin, carboplatin, etoposide) and risedronate sodium against canine and human osteosarcoma (D-17 and U-2 OS). Standard protocols were used for the preparation of cell cultures and evaluation of their viability and apoptosis. MTT assay assessed the culture viability and EC50, while the apoptotic effect of the drugs was checked with a TUNEL assay. Doxorubicin alone showed the strongest cytotoxicity against D-17 (0.056 ± 0.019 µg/mL) and U-2 OS (0.051 ± 0.003 µg/mL), while the lowest cytotoxicity was observed for carboplatin (D-17, 6.45 ± 0.2 µg/mL and U2-OS, 27.5 ± 2.3 µg/mL). Risedronate sodium at 100, 10 and 1 µg/mL lowered viability in OS cell lines by 53.38 ± 1.46 and 49.56 ± 0.7%, 97.08 ± 3.32 and 74.92 ± 4.01%, and 102.67 ± 3.56 and 94.56 ± 3.52%, respectively. In all analyzed drug combinations, risedronate sodium significantly (* p < 0.05) increased the cytotoxicity against tested osteosarcoma cell lines. The decrease in cell viability caused by the studied compound combinations was weaker in canine than in human cell cultures. A combination of doxorubicin (all concentrations), cisplatin (1 µg/mL) and etoposide (1 µg/mL) with 100 µg/mL of risedronate sodium significantly improved the cytotoxicity of the drugs against canine and human osteosarcoma. Administration of carboplatin (1 µg/mL) and risedronate sodium (100 µg/mL), compared to carboplatin per se, produced no significant differences in cytotoxicity against the D-17 cell culture but significantly enhanced cytotoxicity in the U-2 OS line. The strongest apoptosis in both lines was detected for 0.01 µg/mL doxorubicin combined with 100 µg/mL risedronate sodium or 1 µg/mL cisplatin and 100 µg/mL risedronate sodium. In all combinations, the tested compounds revealed a synergistic mechanism of action.

Clinical Application of Artificial Intelligence: Auto-Discerning the Effectiveness of Lidocaine Concentration Levels in Osteosarcoma Femoral Tumor Segment Resection

Adolescents and children worldwide are threatened by osteosarcoma, a tumor that predominantly affects the long bone epiphysis. Osteosarcoma is the most common and highly malignant bone tumor in youngsters. Early tumor detection is the key to effective treatment of this disease. The discovery of biomarkers and the growing understanding of molecules and their complex interactions have improved the outcome of clinical trials in osteosarcoma. This article describes biomarkers of osteosarcoma with the aim of positively influencing the progress of clinical treatment of osteosarcoma. Femoral bone tumor is a typical condition of osteosarcoma. Due to the wide range of femoral stem types, complexities in the distal femur, and tumors in the rotor part of femur, physicians following the traditional clinical approach face difficulties in removing the lesion and fixing the femur with resection of the tumor segment. In this paper, the effect of small doses of different concentrations of lidocaine anesthesia in patients undergoing lumpectomy for osteosarcoma femoral tumor segments is investigated. A computer-based artificial intelligence method for automated determination of different concentration levels of lidocaine anesthesia and amputation of osteosarcoma femoral tumor segment is proposed. Statistical analysis is carried on the empirical data including intraoperative bleeding, intraoperative and postoperative pain scores, surgical operation time, postoperative complications, patient satisfaction, and local anesthetic dose. The results showed that the patients in the study group had low intraoperative bleeding, short operation time, low postoperative hematoma formation rate, high patient satisfaction, higher dosage of anesthetic solution, and low dosage of lidocaine. Results revealed that mean arterial pressure and heart rate in extubating and intubating were significantly lower in the observation group than in the control group, and a significant difference (P < 0.05) was observed between the two groups. This proves that the proposed algorithm can adequately reduce bleeding, alleviate postoperative pain, shorten operation time, reduce complications, accelerate recovery, and ensure better treatment results.

Defucosylated Anti-Epidermal Growth Factor Receptor Monoclonal Antibody (134-mG2a-f) Exerts Antitumor Activities in Mouse Xenograft Models of Canine Osteosarcoma

The epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein. Although EGFR is physiologically essential in normal cells, it contributes to tumor malignancy through gene amplification and/or protein overexpression, which augment signaling cascades in tumor cells. We previously developed an anti-human EGFR (hEGFR) monoclonal antibody (mAb), EMab-134 (mouse IgG₁, kappa), which detects hEGFR and dog EGFR (dEGFR) with high sensitivity and specificity. The mouse IgG_2a version of EMab-134 (134-mG_2a) has antitumor effects toward mouse xenografts of hEGFR-expressing oral squamous cell carcinomas. Furthermore, 134-mG_2a-f, the defucosylated version of 134-mG_2a, exhibits antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) in dEGFR-overexpressed CHO-K1 (CHO/dEGFR) cells and antitumor activities in mouse xenografts of CHO/dEGFR cells. Herein, the reactivity of 134-mG_2a-f against canine cancer cells with endogenous dEGFR was first examined by flow cytometry and immunocytochemistry. In vitro analysis demonstrated that 134-mG_2a-f highly exerted ADCC and CDC for a canine osteosarcoma cell line, D-17, which expresses endogenous dEGFR. Moreover, in vivo administration of 134-mG_2a-f significantly suppressed the development of D-17 compared with the results in response to control mouse IgG. These results suggest that 134-mG_2a-f exerts antitumor effects against dEGFR-expressing canine cancers, and could be valuable as part of an antibody treatment regimen for them.

Limb-Sparing Surgery in Two Cats Using a Femoral Endoprosthesis with an Integrated Total Knee Replacement Implant

OBJECTIVE

 The aim of this study was to describe a novel limb-sparing technique for the management of feline bone neoplasia using a custom-made femoral endoprosthesis in combination with a total knee replacement (TKR) prosthesis.

METHODS

 Two cats with distal femoral bone tumours underwent pelvic limb salvage procedures with custom-made implants designed from patient-specific computed tomography images to replace the distal femur and the stifle. In case 1, the first-generation implant was a combination of a cemented femoral endoprosthesis with a uniaxial hinged cemented TKR prosthesis. Due to aseptic loosening of the endoprosthesis, revision was performed with a second-generation femoral endoprosthesis modified with a short intramedullary peg and a lateral bone plate for immediate stability. In case 2, a third-generation endoprosthesis with an intramedullary peg and two orthogonal bone plates for immediate stability, combined with a custom-designed rotationally hinged cemented TKR prosthesis, was used. Clinical and radiographic follow-up was recorded.

RESULTS

 After revision surgery in case 1 and with the third-generation implant in case 2, no complications were encountered. Both cats showed minor mechanical restriction of stifle range of motion and good clinical long-term outcome without local tumour recurrence.

CLINICAL SIGNIFICANCE

 The combination of a femoral endoprosthesis and a TKR prosthesis can be a viable alternative for distal femoral limb salvage in cats.

Defucosylated Mouse-Dog Chimeric Anti-EGFR Antibody Exerts Antitumor Activities in Mouse Xenograft Models of Canine Tumors

The epidermal growth factor receptor (EGFR) contributes to tumor malignancy via gene amplification and protein overexpression. Previously, we developed an anti-human EGFR (hEGFR) monoclonal antibody, namely EMab-134, which detects hEGFR and dog EGFR (dEGFR) with high sensitivity and specificity. In this study, we produced a defucosylated mouse–dog chimeric anti-EGFR monoclonal antibody, namely E134Bf. In vitro analysis revealed that E134Bf highly exerted antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity against a canine osteosarcoma cell line (D-17) and a canine fibroblastic cell line (A-72), both of which express endogenous dEGFR. Moreover, in vivo administration of E134Bf significantly suppressed the development of D-17 and A-72 compared with the control dog IgG in mouse xenografts. These results indicate that E134Bf exerts antitumor effects against dEGFR-expressing canine cancers and could be valuable as part of an antibody treatment regimen for dogs.

New technologies applied to canine limb prostheses: A review

Although only a few studies have investigated about the development of animal prosthesis, currently, there is an increasing interest in canine limb prosthesis design and its clinical application since they offer an alternative to killing the animal in extreme situations where amputating the limb is the only option. Restoring normal function of amputated canine limbs with the use of a prosthesis is challenging. However, recent advances in surgical procedures and prosthesis design technology appear promising in developing devices that closely recreate normal canine limb function. Surgical advances such as evolution of osseointegration (bone-anchored) prostheses present great promise. Likewise, modern computer-aided design and manufacturing technology, as well as novel motion analysis systems are now providing improved prosthesis designs. Advances in patient-customized prostheses have the potential to reduce the risk of implant failure. The objective of this investigation is to present a general review of the existing literature on modern surgical approaches, design and manufacturing methods, as well as biomechanical analyses so that veterinarians can make more and better-informed decisions on the development and selection of proper canine limb prosthesis. Isolated research efforts have made possible an improvement in stability, comfort, and performance of canine limb prosthesis. However, continued multidisciplinary research collaboration and teamwork among veterinarians, engineers, designers, and industry, with supporting scientific evidence, is required to better understand the development of canine limb prosthesis designs that closely replicate the normal limb function.

Histotripsy Ablation of Bone Tumors: Feasibility Study in Excised Canine Osteosarcoma Tumors

Osteosarcoma (OS) is a primary bone tumor affecting both dogs and humans. Histotripsy is a non-thermal, non-invasive focused ultrasound method using controlled acoustic cavitation to mechanically disintegrate tissue. In this study, we investigated the feasibility of treating primary OS tumors with histotripsy using a 500-kHz transducer on excised canine OS samples harvested after surgery at the Veterinary Teaching Hospital at Virginia Tech. Samples were embedded in gelatin tissue phantoms and treated with the 500-kHz histotripsy system using one- or two-cycle pulses at a pulse repetition frequency of 250 Hz and a dosage of 4000 pulses/point. Separate experiments also assessed histotripsy effects on normal canine bone and nerve using the same pulsing parameters. After treatment, histopathological evaluation of the samples was completed. To determine the feasibility of treating OS through intact skin/soft tissue, additional histotripsy experiments assessed OS with overlying tissues. Generation of bubble clouds was achieved at the focus in all tumor samples at peak negative pressures of 26.2 ± 4.5 MPa. Histopathology revealed effective cell ablation in treated areas for OS tumors, with no evidence of cell death or tissue damage in normal tissues. Treatment through tissue/skin resulted in generation of well-confined bubble clouds and ablation zones inside OS tumors. Results illustrate the feasibility of treating OS tumors with histotripsy.

BAIAP2L2 promotes the proliferation, migration and invasion of osteosarcoma associated with the Wnt/β-catenin pathway

BACKGROUND

Osteosarcoma is the most common bone cancer that significantly affects the quality of life of patients. Studies have shown that overexpression of BAIAP2L2 elevates the proliferation and growth of some types of cancer cells. However, the role of BAIAP2L2 in osteosarcoma is unclear. This study aimed to investigate the functions of BAIAP2L2 in the development of osteosarcoma.

METHODS

We used immunohistochemical and Western blot analysis to determine the expression levels of endogenic BAIAP2L2 in osteosarcoma cells. Cell counting kit-8 assay and colony formation assay were performed to investigate cell proliferation of tumor cells. Transwell assay was performed to detect cell migration. Flow cytometry assay was used to analyze cell apoptosis. The role of BAIAP2L2 in tumor growth was further explored in vivo.

RESULTS

We found that BAIAP2L2 was significantly upregulated in human osteosarcoma, and inhibition of BAIAP2L2 suppressed the proliferation of osteosarcoma cells. In addition, down-regulation of BAIAP2L2 could lead to osteosarcoma cancer cell apoptosis, inhibit cell migration and invasion, and induce the inactivation of the Wnt/β-catenin pathway. In addition, down-regulation of BAIAP2L2 inhibited tumor growth in vivo.

CONCLUSION

In conclusion, down-regulation of BAIAP2L2 inhibited the proliferation, migration, and invasion of osteosarcoma associated with the Wnt/β-catenin pathway.

Novel potent anti-STEAP1 bispecific antibody to redirect T cells for cancer immunotherapy

BACKGROUND

The prognosis for metastatic Ewing sarcoma family of tumors (EFT) is still poor despite high-dose chemotherapy and radiation treatment. Immunotherapies hold promise, but cancer antigen-targeting immunotherapies have largely failed to induce effective T cell receptor-mediated antitumor response. However, T cell-engaging bispecific antibodies (T-BsAbs) have yet to be adequately explored.

METHODS

Rehumanized STEAP1-IgG was used to build T-BsAb (named BC261) using the 2+2 IgG-[L]-scFv platform carrying the anti-CD3 huOKT3 scFv as the second specificity. Its binding epitope mapping, species cross-reactivity, tumor cell line staining, and in vitro cytotoxicity were investigated thoroughly. Its potency in driving tumor-infiltrating lymphocytes (TILs) was quantified using bioluminescence, correlated with in vivo antitumor response against cell line-derived or patient-derived xenografts (CDXs or PDXs) and compared with anti-STEAP1 T-BsAbs built on representative antibody platforms.

RESULTS

BC261 binding epitope was mapped to its second extracellular domain of STEAP1 shared among canine and primate orthologs. BC261 induced potent cytotoxicity against panels of EFT, prostate cancer, and canine osteosarcoma cell lines despite their low antigen density. BC261 drove significantly more TILs into tumors (30-fold) and exerted superior antitumor effects compared with the other standard BsAb platforms. The antitumor efficacy of BC261 was consistent against EFT and prostate cancer CDXs and PDXs.

CONCLUSIONS

BC261 was highly efficient in driving T cell infiltration and tumor ablation. Either as stand-alone therapeutics or for ex vivo armed T cells, this novel anti-STEAP1 T-BsAb BC261 has therapeutic potential.

Immunohistochemical Characterisation of GLUT1, MMP3 and NRF2 in Osteosarcoma

Osteosarcoma (OSA) is an aggressive bone malignancy. Unlike many other malignancies, OSA outcomes have not improved in recent decades. One challenge to the development of better diagnostic and therapeutic methods for OSA has been the lack of well characterized experimental model systems. Spontaneous OSA in dogs provides a good model for the disease seen in people and also remains an important veterinary clinical challenge. We recently used RNA sequencing and qRT-PCR to provide a detailed molecular characterization of OSA relative to non-malignant bone in dogs. We identified differential mRNA expression of the solute carrier family 2 member 1 (SLC2A1/GLUT1), matrix metallopeptidase 3 (MMP3) and nuclear factor erythroid 2–related factor 2 (NFE2L2/NRF2) genes in canine OSA tissue in comparison to paired non-tumor tissue. Our present work characterizes protein expression of GLUT1, MMP3 and NRF2 using immunohistochemistry. As these proteins affect key processes such as Wnt activation, heme biosynthesis, glucose transport, understanding their expression and the enriched pathways and gene ontologies enables us to further understand the potential molecular pathways and mechanisms involved in OSA. This study further supports spontaneous OSA in dogs as a model system to inform the development of new methods to diagnose and treat OSA in both dogs and people.

Cytotoxicity of a Lipid-Rich Extract from Native Mexican Avocado Seed (Persea americana var. drymifolia) on Canine Osteosarcoma D-17 Cells and Synergistic Activity with Cytostatic Drugs

Osteosarcoma is the most common malignant bone tumor in both children and dogs. It is an aggressive and metastatic cancer with a poor prognosis for long-term survival. The search for new anti-cancer drugs with fewer side effects has become an essential goal for cancer chemotherapy; in this sense, the bioactive compounds from avocado have proved their efficacy as cytotoxic molecules. The objective of this study was to determine the cytotoxic and antiproliferative effect of a lipid-rich extract (LEAS) from Mexican native avocado seed (Persea americana var. drymifolia) on canine osteosarcoma D-17 cell line. Also, the combined activity with cytostatic drugs was evaluated. LEAS was cytotoxic to D-17 cells in a concentration-dependent manner with an IC₅₀ = 15.5 µg/mL. Besides, LEAS induced caspase-dependent cell apoptosis by the extrinsic and intrinsic pathways. Moreover, LEAS induced a significant loss of mitochondrial membrane potential and increased superoxide anion production and mitochondrial ROS. Also, LEAS induced the arrest of the cell cycle in the G0/G1 phase. Finally, LEAS improved the cytotoxic activity of cisplatin, carboplatin, and in less extension, doxorubicin against the canine osteosarcoma cell line through a synergistic effect. In conclusion, avocado could be a potential source of bioactive molecules in the searching treatments for osteosarcoma.

Feasibility and safety of whole lung irradiation in the treatment of canine appendicular osteosarcoma

Whole lung irradiation (WLI) has been used successfully in humans as an adjuvant treatment for osteosarcoma. The aim of this study is to describe the feasibility and safety of WLI in dogs with appendicular osteosarcoma. Twelve client-owned dogs with appendicular osteosarcoma that had successfully completed amputation and four doses of carboplatin without evidence of gross metastasis were enrolled in this prospective clinical trial. Ten once-daily fractions of 1.75 Gy were administered to the planning target volume encompassing the lungs. Overall, WLI was well tolerated in these patients. No dogs developed symptoms of pneumonitis or pulmonary fibrosis. Haematopoietic toxicity evaluated during radiation therapy was found to be mild. The median disease free interval for WLI treated dogs was not significantly different than the median DFI for a group of historic control dogs (376 days for WLI treated dogs versus 304.5 days for control dogs; p = 0.5461). Although no significant improvement in outcome was observed with this study, WLI appears to be safe in dogs and warrants further investigation to characterize the efficacy and toxicity.

Molecular Mechanisms of Canine Osteosarcoma Metastasis

Osteosarcoma (OSA) represents the most common bone tumor in dogs. The malignancy is highly aggressive, and most of the dogs die due to metastasis, especially to the lungs. The metastatic process is complex and consists of several main steps. Assessment of the molecular mechanisms of metastasis requires in vitro and especially in vivo studies for a full evaluation of the process. The molecular and biological resemblance of canine OSA to its human counterpart enables the utilization of dogs as a spontaneous model of this disease in humans. The aim of the present review article is to summarize the knowledge of genes and proteins, including p63, signal transducer and activator of transcription 3 (STAT3), Snail2, ezrin, phosphorylated ezrin-radixin-moesin (p-ERM), hepatocyte growth factor-scatter factor (HGF-SF), epidermal growth factor receptor (EGFR), miR-9, and miR-34a, that are proven, by in vitro and/or in vivo studies, to be potentially involved in the metastatic cascade of canine OSA. The determination of molecular targets of metastatic disease may enhance the development of new therapeutic strategies.

Canine osteosarcoma checkpoint expression correlates with metastasis and T-cell infiltrate

BACKGROUND

Immune-targeted therapies are being successfully implemented into cancer clinical practice. In particular checkpoint inhibitors are employed to modulate the immune microenvironment of solid tumors. We sought to determine the expression of PD-L1, HVEM, and B7H3 in human and canine osteosarcoma, and correlate expression with clinical features and tumor infiltrating lymphocytes in naturally-occurring canine osteosarcoma.

METHODS

Flow cytometry was used to measure ligand surface expression of five human and three canine cell lines. Immunohistochemistry was utilized for expression of ligands and lymphocyte markers in thirty-seven treatment-naïve canine osteosarcoma patients.

RESULTS

All cell lines expressed all three ligands at variable levels in both species. Metastatic lesions were associated with higher expression of all three ligands in patient tumor samples. PD-L1 expression strongly correlated with B7H3 and HVEM expression, while HVEM and B7H3 were weakly correlated. Whereas peritumoral T-cell expression positively correlated with PD-L1 and HVEM tumor expression, the presence of T-cells intratumorally were rare. Furthermore, intratumor penetration by T-cells was greatest in metastatic lesions, despite log-fold increases in peritumoral T-cells. In summary, PD-L1, HVEM, and B7H3 are expressed in osteosarcoma, with metastatic disease lesions expressing higher levels. We show for the first time that these ligands expressed on osteosarcoma cells positively correlate with each other and the presence of peritumoral T cell infiltration. Furthermore, osteosarcoma appears to be an intratumoral immune desert with significant resistance to effector T cells. Multiple agents targeting checkpoints are in clinical practice, and may have immune modulating benefit in osteosarcoma.

Targeting Mechanotransduction in Osteosarcoma: A Comparative Oncology Perspective

Mechanotransduction is the process in which cells can convert extracellular mechanical stimuli into biochemical changes within a cell. While this a normal process for physiological development and function in many organ systems, tumour cells can exploit this process to promote tumour progression. Here we summarise the current state of knowledge of mechanotransduction in osteosarcoma (OSA), the most common primary bone tumour, referencing both human and canine models and other similar mesenchymal malignancies (e.g., Ewing sarcoma). Specifically, we discuss the mechanical properties of OSA cells, the pathways that these cells utilise to respond to external mechanical cues, and mechanotransduction-targeting strategies tested in OSA so far. We point out gaps in the literature and propose avenues to address them. Understanding how the physical microenvironment influences cell signalling and behaviour will lead to the improved design of strategies to target the mechanical vulnerabilities of OSA cells.

Oncogenic roles of lncRNA BLACAT1 and its related mechanisms in human cancers

Long non-coding RNAs (lncRNAs) play indispensable roles in mediating regulation of epigenetics, and their dysregulation is strongly associated with the initiation and progression of human cancers. Recently, lncRNA bladder cancer-associated transcript 1 (BLACAT1) has been observed to exert oncogenic effects on cancers, including glioma, breast cancer, lung cancer, hepatocellular carcinoma, gastric cancer, colorectal cancer, ovarian cancer, cervical cancer and osteosarcoma. Additional mechanical analyses have uncovered that lncRNA BLACAT1 is positively correlated with tumor stage, lymph node metastasis and distant metastasis of primary tumors via involvement with various cellular activities, thus leading to poor overall survival and progression-free survival (PFS). In this review, we generalize the oncogenic roles of BLACAT1 in multiple human cancers through correlation with clinical implications and cellular activities. Moreover, we forecast its potential clinical application as a novel biomarker and a promising therapeutic target for cancers.

microRNA-524-5p inhibits proliferation and induces cell cycle arrest of osteosarcoma cells via targeting CDK6

BACKGROUND

Osteosarcoma (OS) is one of the most commonly diagnosed malignant tumors that mainly affects children and adolescents. The underlying molecular mechanisms that are responsible for the initiation and development of OS are still not clear. Increasing evidence suggested the tumor suppressor role of microRNA-524-5p in a variety of cancers via targeting key pathways involved in tumorigenesis. The aim of this study was to characterize the function of miR-524-5p in OS.

METHODS

A total 50 paired OS tissues and adjacent normal tissues were collected from OS patients. The expression of miR-524-5p in OS tissues and cells was detected by RT-qPCR. The CCK-8 assay, flow cytometry and transwell assay were applied to determine the proliferation and invasion abilities of OS cells. The targets of miR-524-5p were predicted using the miRDB dataset and confirmed by luciferase reporter assay and western blot analysis.

RESULTS

The expression of miR-524-5p was decreased in OS tissues and cell lines. OS patients with lymph node metastasis harbored relative lower level of miR-524-5p. Overexpression of miR-524-5p in OS cells significantly suppressed the proliferation, drove cell cycle arrest and apoptosis. The mechanism investigation revealed that miR-524-5p bound the 3'-untranslated region (UTR) of Cyclin Dependent Kinase 6 (CDK6) and repressed the expression of CDK6 in OS cells. Overexpressed CDK6 was found in OS tissues, which was inversely correlated with that of miR-524-5p. Moreover, forced expression of CDK6 significantly reversed the anti-cancer effects of miR-524-5p on the proliferation, apoptosis and cell cycle arrest of OS cells.

CONCLUSIONS

Our results identified the tumor-suppressive role of miR-524-5p in OS via targeting CDK6, which may lead to the identification of novel therapeutic target for the treatment of OS.

Anticancer Effects of Cold Atmospheric Plasma in Canine Osteosarcoma Cells

Osteosarcoma is known to be one of the frequently occurring cancers in dogs. Its prognosis is usually very poor, with a high incidence of lung metastasis. Although radiation therapy has become a major therapeutic choice for canine osteosarcoma, the high costs and unexpected side effects prevent some patients from considering this treatment. Cold atmospheric plasma (CAP) is an ionized gas with high energy at low temperatures, and it produces reactive oxygen species that mediate many signaling pathways. Although many researchers have used CAP as an anticancer therapeutic approach in humans, its importance has been neglected in veterinary medicine. In this study, D-17 and DSN canine osteosarcoma cell lines were treated with CAP to observe its anticancer activity. By high-content screening and flow cytometry, CAP-treated cells showed growth arrest and apoptosis induction. Moreover, the osteosarcoma cells exhibited reduced migration and invasion activity when treated with CAP. Overall, CAP exerted an anticancer effect on canine osteosarcoma cell lines. CAP may have the potential to be used as a novel modality for treating cancer in veterinary medicine.

Inhibition of copper chaperones sensitizes human and canine osteosarcoma cells to carboplatin chemotherapy

Osteosarcoma (OSA) is the most common primary bone cancer in children, adolescents and dogs. Current combination surgical and chemotherapeutic treatments have increased survival. However, in recurrent or metastatic disease settings, the prognosis significantly decreases, representing an urgent need for better second-line and novel chemotherapeutics. The current gold standard for combination chemotherapy in OSA often includes a platinum agent, for example, cisplatin or carboplatin. These platinum agents are shuttled within the cell via copper transporters. Recent interest in targeting copper transport has been directed towards antioxidant protein 1 (Atox1) and copper chaperone for superoxide dismutase 1 (CCS), with Atox1 demonstrating the ability to aggregate platinum agents, preventing them from forming DNA adducts. DC_AC50 is a small molecule inhibitor of both Atox1 and CCS. To assess the impact of targeting these pathways on chemotherapy response, two human and two canine OSA cell lines were utilized. After treatment with single agent or combination drugs, cell viability was evaluated and pharmacological synergism calculated using the combination index method. Apoptosis, cell cycle distribution, clonogenic survival and migration were also evaluated. DC_AC50 synergised with carboplatin in combination treatment of human and canine OSA cells to reduce cancer cell viability. DC_AC50-treated cells were significantly less mitotically active, as demonstrated by decreased expression of phospho-histone H3 and cell cycle analysis. DC_AC50 also potentiated carboplatin-induced apoptosis in OSA cells and decreased clonogenic survival. Finally, DC_AC50 reduced the migratory ability of OSA cells. These results justify further investigation into inhibiting intracellular copper chaperones as a means of reducing/preventing acquired chemotherapy resistance.

Predictive modeling for cancer drug discovery using canine models

INTRODUCTION

Rodent models of cancer lack many features associated with the disease in humans. Because dogs closely share an environment with humans, as well as comparable pathophysiology of cancer, they represent a powerful model with which to study novel approaches to cancer treatment.

AREAS COVERED

The authors summarize the weaknesses of rodent models of cancer and the ongoing need for better animal models with which to study potential therapeutic approaches. The homology of cancer in dogs and humans is described, along with examples specific to several common cancer types.

EXPERT OPINION

Laboratory mice and rats will continue to play a central role in cancer research; however, because of a variety of limitations, pet dogs with spontaneous cancer offer unique opportunities for research and should be included in the preclinical development of therapeutic compounds. Environmental homology between dogs and humans, along with biological and molecular similarities present circumstances that strengthen the translational rigor of studies conducted using canine patients. Progress will depend on a sufficient number of dogs to be diagnosed with cancer and available for use in studies; and essential to this will be the availability of enhanced resources for diagnosis of cancer in canine patients and reliable coordination between research scientists, veterinarians, and physicians.

The Potential Selective Cytotoxicity of Poly (L- Lactic Acid)-Based Scaffolds Functionalized with Nanohydroxyapatite and Europium (III) Ions toward Osteosarcoma Cells

Osteosarcoma (OSA) is malignant bone tumor, occurring in children and adults, characterized by poor prognosis. Despite advances in chemotherapy and surgical techniques, the survival of osteosarcoma patients is not improving significantly. Currently, great efforts are taken to identify novel selective strategies, distinguishing between cancer and normal cells. This includes development of biomimetic scaffolds with anticancer properties that can simultaneously support and modulate proper regeneration of bone tissue. In this study cytotoxicity of scaffolds composed from poly (L-lactic acid) functionalized with nanohydroxyapatite (nHAp) and doped with europium (III) ions-10 wt % 3 mol % Eu³⁺: nHAp@PLLA was tested using human osteosarcoma cells: U-2 OS, Saos-2 and MG-63. Human adipose tissue-derived stromal cells (HuASCs) were used as non-transformed cells to determine the selective cytotoxicity of the carrier. Analysis included evaluation of cells morphology (confocal/scanning electron microscopy (SEM)), metabolic activity and apoptosis profile in cultures on the scaffolds. Results obtained indicated on high cytotoxicity of scaffolds toward all OSA cell lines, associated with a decrease of cells' viability, deterioration of metabolic activity and activation of apoptotic factors determined at mRNA and miRNA levels. Simultaneously, the biomaterials did not affect HuASCs' viability and proliferation rate. Obtained scaffolds showed a bioimaging function, due to functionalization with luminescent europium ions, and thus may find application in theranostics treatment of OSA.

Aldoxorubicin-loaded nanofibers are cytotoxic for canine mammary carcinoma and osteosarcoma cell lines in vitro: A short communication

Chemotherapeutic drugs are given parenterally to treat various canine tumors. A limitation of parenteral administration is low drug penetration into the tumor, which reduces tumoricidal activity. Various drug carriers have been used to enhance tumor delivery, including albumin, liposomes and nanoparticles. A novel peptide-based nanofiber precursor (NFP) has been developed that is designed to take advantage of the leaky tumor neovasculature to promote drug delivery after parenteral administration. In this study, we loaded aldoxorubicin, an albumin-bound prodrug version of doxorubicin, onto NFP and tested the in vitro cytotoxicity in canine mammary carcinoma (CMT12, CMT25) and osteosarcoma (HMPOS, D-17, Abrams) cell lines. The half maximal inhibitory concentration (IC50) was determined with a luminescence-based cell viability assay. The IC50 for aldoxorubicin-loaded NFP was lower than free aldoxorubicin or doxorubicin in all cell lines, whereas non-drug loaded NFP had no cytotoxic effects. There were differences in IC50 between the osteosarcoma lines, with lower and higher IC50 for HMPOS and D-17 cells, respectively, with all drugs (aldoxorubicin-loaded NFP, free aldoxorubicin or free doxorubicin). Our results indicate that drug-loaded NFPs are cytotoxic for various canine mammary carcinoma and osteosarcoma cell lines in vitro and hold promise as a mechanism for enhancing delivery of chemotherapeutic agents to canine tumors.

Melarsomine suppresses canine osteosarcoma cell survival via inhibition of Hedgehog-GLI signaling

The Hedgehog-GLI signaling pathway is activated in human and canine osteosarcoma (OSA) and represents a potential therapeutic target for cancers, including OSA. Arsenic trioxide represses GLI expression. Melarsomine, an arsenic compound-containing drug, has been approved for the treatment of canine heartworm disease. Hence, we hypothesized that melarsomine inhibits GLI signaling in canine OSA cell lines. The present study aimed to assess this hypothesis. Cell viability and colony formation were decreased in the canine OSA cell lines Abrams and D17 after treatment with melarsomine. Melarsomine-induced apoptotic cell death was assessed via cell cycle analysis using propidium iodide staining. Quantitative real-time reverse transcription polymerase chain reaction and western blot analyses revealed a downregulation of genes downstream of the Hedgehog signaling pathway, including GLI1, GLI2, and PTCH, after melarsomine treatment. The present results suggest that melarsomine exerts antitumor effects and serves as a GLI inhibitor in canine OSA cells. Additional studies are required to evaluate and confirm the anticancer effect and relevant therapeutic dose of melarsomine in vivo.

Down-regulation of RAC2 by small interfering RNA restrains the progression of osteosarcoma by suppressing the Wnt signaling pathway

Osteosarcoma (OS) is the most common primary malignancy of bone and is characterized by a high malignant and metastatic potential. Microarray-based differentially expressed gene screening determined RAC2 as the candidate gene related to OS. Highly expressed RAC2 and activated Wnt signaling pathway were determined in OS tissues using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The OS cells were transfected with siRNA-RAC2 or treated with BIO (activator of Wnt pathway), whereby the effects of siRNA-RAC2 on cell proliferation, invasion, cycle and apoptosis were analyzed by CCK-8, Transwell assay and flow cytometry. The mRNA and protein levels of RAC2 and the Wnt signaling pathway-, proliferation- and apoptosis-related genes in OS cells were determined by RT-qPCR and Western blot assay. Importantly, siRNA-mediated RAC2 silencing inhibited the activation of the Wnt signaling pathway in OS. siRNA-RAC2 inhibited the proliferation and invasion, while impeded OS cell cycle progression and facilitated cell apoptosis. However, activation of Wnt signaling pathway reversed the effects of siRNA-RAC2. Finally, orthotopic xenograft OS mouse model confirmed the in vivo anti-tumor effects by silencing RAC2. Taken together, RAC2 gene silencing could suppress OS progression. The mechanism was obtained by inhibiting the activation of the Wnt signaling pathway.

Efficacy of an anti-cancer strategy targeting SET in canine osteosarcoma

Osteosarcoma (OSA) is the most common bone tumor in dogs. Protein phosphatase 2A (PP2A), an evolutionary conserved serine/threonine protein phosphatase, is a crucial tumor suppressor. SET is a PP2A inhibitory protein that directly interacts with PP2A and suppresses its phosphatase activity. SET has been reported as a contributor of wide range of human and dog tumor malignancies. However, the role of SET in canine OSA (cOSA) remains unknown. In this study, we investigated the role of SET in cOSA by using 2 cOSA cell lines: POS (primary origin) and HM-POS (metastatic origin). Knockdown (KD) of SET expression was noted to slightly suppress POS cell proliferation only. Furthermore, SET KD effectively suppressed colony formation ability of both POS and HM-POS cells. SET KD was observed to repress ERK1/2, mTOR, E2F1, and NF-κB signaling in HM-POS cells, whereas it inhibited only ERK1/2 signaling in POS. Further, it was observed that SET-targeting drug, FTY720, exerted anti-cancer effects in both POS and HM-POS cells. Moreover, the drug also enhanced the anti-cancer effect of cisplatin. The data suggested that a combination therapy, based on SET targeting drugs and cisplatin, could be a potent strategy for cOSA.

Personalized 3D-printed endoprostheses for limb sparing in dogs: Modeling and in vitro testing

Osteosarcoma is the most common type of bone cancer in dogs, treatable by amputation or limb-sparing surgery. For the latter, commercially available plate - endoprosthesis assemblies require contouring, to be adapted to the patient's bone geometry, and lead to sub-optimal results. The use of additively-manufactured personalized endoprostheses and cutting guides for distal radius limb-sparing surgery in dogs presents a promising alternative. Specialized software is used for the bone structure reconstruction from the patient's CT scans and for the design of endoprostheses and cutting guides. The prostheses are manufactured from a titanium alloy using a laser powder bed fusion system, while the cutting guides are manufactured from an ABS plastic using a fused deposition modeling system. A finite element model of an instrumented limb was developed and validated using experimental testing of a cadaveric limb implanted with a personalized endoprosthesis. Personalized endoprostheses and cutting guides can reduce limb sparing surgery time by 25-50% and may reduce the risk of implant failure. The numerical model was validated using the kinematics and force-displacement diagrams of the implant-limb construct. The model indicated that a modulus of elasticity of an implant material ranging from 25 to 50 GPa would improve the stress distribution within the implant. The results of the current study will allow optimization of the design of the personal implants in both veterinary and human patients.

YM155 enhances the cytotoxic activity of etoposide against canine osteosarcoma cells

Canine osteosarcoma (OSA) is an aggressive and highly malignant primary bone tumor. Its poor survival outcome remains problematic despite recent advances in anti-cancer therapy, therefore highlighting the need for alternative treatment options or drug repositioning. The aim of this study was to determine if YM155, a small-molecule survivin inhibitor, potentiates the chemotherapeutic efficacy of etoposide against canine OSA in vitro and in vivo. In cell culture, YM155 enhanced the cytotoxic effect of etoposide against canine OSA cell lines; however, the molecular mechanism behind this effect was heterogeneous, as only one cell line had an elevated apoptotic level. In addition, this effect was not associated with survivin suppression in two of the cell lines. These results suggest that the molecular target of YM155 is not restricted to survivin alone. When tested on a murine xenograft model, the average tumor volume of the combination treatment group (YM155, 5 mg/kg, intraperitoneally, 5 consecutive days/week; and etoposide, 20 mg/kg, intraperitoneally, every 5 days) was 66% smaller than the control group, although this difference was not statistically significant (P=0.17). Further studies to improve the treatment protocol are necessary to confirm the findings of this study.

In vitro effects of the activity of novel platinum (II) complex in canine and human cell lines

The anticancer activity of novel platinum derivative, a complex of platinum with tris(2-carboxyethyl)phosphine (Pt-TCEP), has been evaluated in canine (D-17) and human osteosarcoma (U2-OS) cell lines. Viability of cells after incubation for 24 or 72 hours with increasing concentrations (0.625, 1.25, 2.50, 5, 10 and 20 μM) of Pt-TCEP was tested in an MTT assay and compared to effect of cisplatin. Longer-term effect of Pt-TCEP was evaluated in the colony-forming unit assay after 24 hours exposure to the Pt-TCEP (2 and 3 μM) and subsequent incubation for 2 weeks. The influence of the compound on the cell cycle was measured after 24 hours treatment with Pt-TCEP (3 μM). Its pro-apoptotic activity was examined after 24 hours treatment with Pt-TCEP (1.25, 2.50, 5, 10 and 20 μM) using flow cytometry. Expression of main proteins involved in apoptosis was measured after exposure for 24 hours to 3 or 5 μM Pt-TCEP in Western Blot. The compound much more effectively decreased cell viability than cisplatin in case of both cell lines. IC₅₀ of Pt-TCEP was 5.93 ± 0.12 in D-17 and 3.45 ± 0.14 in U2-OS cell lines after 24 hours, and 1.77 ± 0.14 in D-17 and 1.53 ± 0.11 in U2-OS after 72 hours (P < .05). The compound arrested cells in the G2/M phase and inhibited the ability of cells to form colonies. Pt-TCEP induced caspase-dependent apoptosis. The expression of the anti-apoptotic Bcl-X_L protein was decreased after Pt-TCEP treatment in both cell lines. The results confirmed anti-cancer activity of Pt-TCEP against canine and human osteosarcoma cell lines.

Surgical decompression, with or without adjunctive therapy, for palliative treatment of primary vertebral osteosarcoma in dogs

Vertebral osteosarcoma (OSA) is the most common primary vertebral tumor in dogs, however studies examining the survival time after surgical decompression of these tumors are limited. There is also limited information regarding the benefit of adjunctive treatments such as radiation therapy or chemotherapy in these patients. The goal of this study was to determine survival time of dogs with primary vertebral OSA after palliative decompressive surgery alone and combined with radiation therapy and/or chemotherapy. Records from 22 client-owned dogs diagnosed with primary vertebral OSA and treated with decompressive surgery were collected retrospectively from eight referral institutions. Survival time was assessed for dogs treated with surgery alone as well as dogs who received adjunctive radiation therapy and/or chemotherapy. Median survival time in the 12 dogs treated with surgery alone was 42 days (range: 3-1333 days). The three dogs treated with surgery and chemotherapy had a median survival time of 82 days (range: 56-305 days). Only one dog was treated with surgery and radiation therapy; this dog survived 101 days. Six dogs were treated with surgery, radiation therapy and chemotherapy; these dogs had a median survival time of 261 days (range: 223-653 days). Cause of death in all cases that survived the initial postoperative period was euthanasia secondary to confirmed or suspected tumor regrowth. The results of this study suggest that definitive radiation therapy, possibly combined with concurrent chemotherapy, significantly improves survival in dogs treated with palliative decompressive surgery for vertebral OSA and should be the treatment of choice in selected cases.