Murine models of osteosarcoma: A piece of the translational puzzle

The generation and use of animal models of osteosarcoma in cancer research

Osteosarcoma is the most common malignant bone tumor affecting children and adolescents. Currently, the most common treatment is surgery combined with neoadjuvant chemotherapy. Although the survival rate of patients with osteosarcoma has improved in recent years, it remains poor when the tumor(s) progress and distant metastases develop. Therefore, better animal models that more accurately replicate the natural progression of the disease are needed to develop improved prognostic and diagnostic markers, as well as targeted therapies for both primary and metastatic osteosarcoma. The present review described animal models currently being used in research investigating osteosarcoma, and their characteristics, advantages, and disadvantages. These models may help elucidate the pathogenic mechanism(s) of osteosarcoma and provide evidence to support and develop clinical treatment strategies.

Cellular dynamics of distinct skeletal cells and the development of osteosarcoma

Bone contributes to the maintenance of vital biological activities. At the cellular level, multiple types of skeletal cells, including skeletal stem and progenitor cells (SSPCs), osteoblasts, chondrocytes, marrow stromal cells, and adipocytes, orchestrate skeletal events such as development, aging, regeneration, and tumorigenesis. Osteosarcoma (OS) is a primary malignant tumor and the main form of bone cancer. Although it has been proposed that the cellular origins of OS are in osteogenesis-related skeletal lineage cells with cancer suppressor gene mutations, its origins have not yet been fully elucidated because of a poor understanding of whole skeletal cell diversity and dynamics. Over the past decade, the advent and development of single-cell RNA sequencing analyses and mouse lineage-tracing approaches have revealed the diversity of skeletal stem and its lineage cells. Skeletal stem cells (SSCs) in the bone marrow endoskeletal region have now been found to efficiently generate OS and to be robust cells of origin under p53 deletion conditions. The identification of SSCs may lead to a more limited redefinition of bone marrow mesenchymal stem/stromal cells (BM-MSCs), and this population has been thought to contain cells from which OS originates. In this mini-review, we discuss the cellular diversity and dynamics of multiple skeletal cell types and the origin of OS in the native in vivo environment in mice. We also discuss future challenges in the study of skeletal cells and OS.

Recent and Ongoing Research into Metastatic Osteosarcoma Treatments

The survival rate for metastatic osteosarcoma has not improved for several decades, since the introduction and refinement of chemotherapy as a treatment in addition to surgery. Over two thirds of metastatic osteosarcoma patients, many of whom are children or adolescents, fail to exhibit durable responses and succumb to their disease. Concerted efforts have been made to increase survival rates through identification of candidate therapies via animal studies and early phase trials of novel treatments, but unfortunately, this work has produced negligible improvements to the survival rate for metastatic osteosarcoma patients. This review summarizes data from clinical trials of metastatic osteosarcoma therapies as well as pre-clinical studies that report efficacy of novel drugs against metastatic osteosarcoma in vivo. Considerations regarding the design of animal studies and clinical trials to improve survival outcomes for metastatic osteosarcoma patients are also discussed.

Biomarker potential of lncRNA GNAS-AS1 in osteosarcoma prognosis and effect on cellular function

BACKGROUND

Osteosarcoma (OS) is a type of bone cancer that occurs in children and adolescents at a rate of 5%. The purpose of this study is to explore the lncRNA GNAS-AS1 expression profile, prognosis significance in OS, and biological effect on OS cell function.

METHODS

One hundred eight pairs of tissues were collected, and OS cell lines were purchased. lncRNA GNAS-AS1 expression in these tissues and cells were analyzed by qRT-PCR. Clinical data were analyzed using chi-square tests, Kaplan-Meier curves (log-rank test), and Cox regression. CCK-8 and transwell assay were conducted to analyze the effect of lncRNA GNAS-AS1 on cell proliferation, invasion, and migration. The downstream miRNA was presumed.

RESULTS

The expression of lncRNA GNAS-AS1 was significantly increased in OS cells and tissues, and related to Enneking staging and distant metastasis. Patients with high lncRNA GNAS-AS1 expression represented shorter overall survival and was an independent prognostic predictor of OS. LncRNA GNAS-AS1 knockdown inhibited cell proliferation, migration, and invasion by regulated miR-490-3p partly at least.

CONCLUSIONS

LncRNA GNAS-AS1 can be used as a prognostic indicator and its inhibition suppress the development of OS, suggesting its value as novel therapeutic strategies in OS.

Physiological and Pharmacological Roles of PTH and PTHrP in Bone Using Their Shared Receptor, PTH1R

Parathyroid hormone (PTH) and the paracrine factor, PTH-related protein (PTHrP), have preserved in evolution sufficient identities in their amino-terminal domains to share equivalent actions upon a common G protein-coupled receptor, PTH1R, that predominantly uses the cyclic adenosine monophosphate-protein kinase A signaling pathway. Such a relationship between a hormone and local factor poses questions about how their common receptor mediates pharmacological and physiological actions of the two. Mouse genetic studies show that PTHrP is essential for endochondral bone lengthening in the fetus and is essential for bone remodeling. In contrast, the main postnatal function of PTH is hormonal control of calcium homeostasis, with no evidence that PTHrP contributes. Pharmacologically, amino-terminal PTH and PTHrP peptides (teriparatide and abaloparatide) promote bone formation when administered by intermittent (daily) injection. This anabolic effect is remodeling-based with a lesser contribution from modeling. The apparent lesser potency of PTHrP than PTH peptides as skeletal anabolic agents could be explained by lesser bioavailability to PTH1R. By contrast, prolongation of PTH1R stimulation by excessive dosing or infusion, converts the response to a predominantly resorptive one by stimulating osteoclast formation. Physiologically, locally generated PTHrP is better equipped than the circulating hormone to regulate bone remodeling, which occurs asynchronously at widely distributed sites throughout the skeleton where it is needed to replace old or damaged bone. While it remains possible that PTH, circulating within a narrow concentration range, could contribute in some way to remodeling and modeling, its main physiological role is in regulating calcium homeostasis.

Non-rodent animal models of osteosarcoma: A review

Osteosarcoma is extremely malignant, and the most common cancer that affects bone. Current treatments involve surgical resection of the affected area and multi-agent chemotherapy, though survival rate is generally poor for those affected by metastases. As treatment for osteosarcoma has remained unchanged for the past few decades, there is a need for further advancements in the understanding of osteosarcoma biology and therapeutics. Thus, reliable animal models that can accurately recapitulate the disease are required. Though rodents represent the most popular animal model of osteosarcoma, they may not model the disease best. This review analyzes emerging alternative non-rodent animal models of osteosarcoma, such as the chick chorioallantoic membrane (CAM) assay, pigs, and canines. Each of these alternatives offer advantages over classic rodent models for pre-clinical research. Research of these cross-species platforms imparts knowledge of metastases biology and potential new treatments for osteosarcoma.

Genetically Engineered Pigs to Study Cancer

Recent decades have seen groundbreaking advances in cancer research. Genetically engineered animal models, mainly in mice, have contributed to a better understanding of the underlying mechanisms involved in cancer. However, mice are not ideal for translating basic research into studies closer to the clinic. There is a need for complementary information provided by non-rodent species. Pigs are well suited for translational biomedical research as they share many similarities with humans such as body and organ size, aspects of anatomy, physiology and pathophysiology and can provide valuable means of developing and testing novel diagnostic and therapeutic procedures. Porcine oncology is a new field, but it is clear that replication of key oncogenic mutation in pigs can usefully mimic several human cancers. This review briefly outlines the technology used to generate genetically modified pigs, provides an overview of existing cancer models, their applications and how the field may develop in the near future.

The correlation between the methylation of PTEN gene and the apoptosis of osteosarcoma cells mediated by SeHA nanoparticles

The invasive spreading of residual osteosarcoma cells becomes a serious threat to human health, urgently needing new bone regenerative biomaterials for orthopedic therapy. Thus, in this work, selenite-substituted hydroxyapatite (SeHA) nanoparticles were prepared for both inhibiting the recurrence of the tumor and accelerating the regenerative repair of bone defect. Physicochemical characterization showed these synthetic nanoparticles were spherical poly-crystals with the shape of snowflakes. Such structure benefited them to inhibit the cellular viability of osteosarcoma cells by about (58.90 ± 14.37)% during 24 h co-culturing. The expression level of cell growth-related genes such as PTEN, MMP-9, Cyclin D1, Cyclin A2, Annexin A2 and CDC2 decreased. Bisulfite Sequence PCR of PTEN gene exhibited about (22.40 ± 5.39)%, (45.91 ± 6.36)% and (25.90 ± 5.36)% promoter methylation in control, HA and SeHA group. Animal experiment also proved the similar effects. Almost no recurrence were observed in SeHA group. Oppositely, the slowly recurrent growth of the remnant tumor appeared in purely surgical group. The overall survival and toxicity analysis showed that, in the usage dose of 0-0.1 g, the SeHA-0.01 exhibited higher inhibitory recurrence and metastasis potentials, lower renal toxicity and better anti-inflammation function. Immunohistochemistry stain showed the reduced expression of PTEN, MMP-9, Ki-67 and Annexin A2, but slightly increased expression of DNMT1 and BMP-2. Compared the methylation status of PTEN gene in each group, it was confirming that SeHA nanoparticles hardly possessed the de-methylation effect, but the pure HA strikingly increased the methylation level of such gene. It seemed the dopant selenite ions possessed de-methylation effect onto PTEN gene. Therefore, from the viewpoint of inhibiting metastatic potentials, the SeHA-0.01 might be a feasible biomaterial to inhibit the relapse of the tumor post-surgery.

Osteosarcoma in the Post Genome Era: Preclinical Models and Approaches to Identify Tractable Therapeutic Targets

PURPOSE OF REVIEW

Osteosarcoma (OS) is the most common cancer of bone, yet is classified as a rare cancer. Treatment and outcomes for OS have not substantively changed in several decades. While the decoding of the OS genome greatly advanced the understanding of the mutational landscape of OS, immediately actionable therapeutic targets were not apparent. Here we describe recent preclinical models that can be leveraged to identify, test, and prioritize therapeutic candidates.

RECENT FINDINGS

The generation of multiple high fidelity murine models of OS, the spontaneous disease that arises in pet dogs, and the establishment of a diverse collection of patient-derived OS xenografts provide a robust preclinical platform for OS. These models enable evidence to be accumulated across multiple stages of preclinical evaluation. Chemical and genetic screening has identified therapeutic targets, often demonstrating cross species activity. Clinical trials in both PDX models and in canine OS have effectively tested new therapies for prioritization. Improving clinical outcomes in OS has proven elusive. The integrated target discovery and testing possible through a cross species platform provides validation of a putative target and may enable the rigorous evaluation of new therapies in models where endpoints can be rapidly assessed.

Smac mimetics LCL161 and GDC-0152 inhibit osteosarcoma growth and metastasis in mice

BACKGROUND

Current therapies fail to cure over a third of osteosarcoma patients and around three quarters of those with metastatic disease. "Smac mimetics" (also known as "IAP antagonists") are a new class of anti-cancer agents. Previous work revealed that cells from murine osteosarcomas were efficiently sensitized by physiologically achievable concentrations of some Smac mimetics (including GDC-0152 and LCL161) to killing by the inflammatory cytokine TNFα in vitro, but survived exposure to Smac mimetics as sole agents.

METHODS

Nude mice were subcutaneously or intramuscularly implanted with luciferase-expressing murine 1029H or human KRIB osteosarcoma cells. The impacts of treatment with GDC-0152, LCL161 and/or doxorubicin were assessed by caliper measurements, bioluminescence, 18FDG-PET and MRI imaging, and by weighing resected tumors at the experimental endpoint. Metastatic burden was examined by quantitative PCR, through amplification of a region of the luciferase gene from lung DNA. ATP levels in treated and untreated osteosarcoma cells were compared to assess in vitro sensitivity. Immunophenotyping of cells within treated and untreated tumors was performed by flow cytometry, and TNFα levels in blood and tumors were measured using cytokine bead arrays.

RESULTS

Treatment with GDC-0152 or LCL161 suppressed the growth of subcutaneously or intramuscularly implanted osteosarcomas. In both models, co-treatment with doxorubicin and Smac mimetics impeded average osteosarcoma growth to a greater extent than either drug alone, although these differences were not statistically significant. Co-treatments were also more toxic. Co-treatment with LCL161 and doxorubicin was particularly effective in the KRIB intramuscular model, impeding primary tumor growth and delaying or preventing metastasis. Although the Smac mimetics were effective in vivo, in vitro they only efficiently killed osteosarcoma cells when TNFα was supplied. Implanted tumors contained high levels of TNFα, produced by infiltrating immune cells. Spontaneous osteosarcomas that arose in genetically-engineered immunocompetent mice also contained abundant TNFα.

CONCLUSIONS

These data imply that Smac mimetics can cooperate with TNFα secreted by tumor-associated immune cells to kill osteosarcoma cells in vivo. Smac mimetics may therefore benefit osteosarcoma patients whose tumors contain Smac mimetic-responsive cancer cells and TNFα-producing infiltrating cells.

Upregulated TTYH2 expression is critical for the invasion and migration of U2OS human osteosarcoma cell lines

Ion channels have recently emerged as stable biomarkers and anticancer targets particularly when the applications of the currently available therapeutic regimens are limited, as in case of osteosarcoma, a malignant bone tumor. Here, we evaluated the expression of TTYH2, a presumably calcium-activated chloride channel, in a human osteosarcoma cell line U2OS. We used small-interfering RNA (siRNA)-mediated gene silencing to demonstrate the downregulation in the expression of TTYH2 that resulted in the decrease in the invasion and migration, but not proliferation, of U2OS cells. The expression levels of Slug and ZEB1, the transcription factors involved in epithelial-mesenchymal transition, significantly reduced after TTYH2 silencing. Based on these results, we suggest that TTYH2 may serve as a novel target for the treatment of osteosarcoma.

Risk-modeling of dog osteosarcoma genome scans shows individuals with Mendelian-level polygenic risk are common

Background

Despite the tremendous therapeutic advances that have stemmed from somatic oncogenetics, survival of some cancers has not improved in 50 years. Osteosarcoma still has a 5-year survival rate of 66%. We propose the natural canine osteosarcoma model can change that: it is extremely similar to the human condition, except for being highly heritable and having a dramatically higher incidence. Here we reanalyze published genome scans of osteosarcoma in three frequently-affected dog breeds and report entirely new understandings with immediate translational indications.

Results

First, meta-analysis revealed association near FGF9, which has strong biological and therapeutic relevance. Secondly, risk-modeling by multiple logistic regression shows 22 of the 34 associated loci contribute to risk and eight have large effect sizes. We validated the Greyhound stepwise model in our own, independent, case-control cohort. Lastly, we updated the gene annotation from approximately 50 genes to 175, and prioritized those using cross-species genomics data. Mostly positional evidence suggests 13 genes are likely to be associated with mapped risk (including MTMR9, EWSR1 retrogene, TANGO2 and FGF9). Previous annotation included seven of those 13 and prioritized four by pathway enrichment. Ten of our 13 priority genes are in loci that contribute to risk modeling and thus can be studied epidemiologically and translationally in pet dogs. Other new candidates include MYCN, SVIL and MIR100HG.

Conclusions

Polygenic osteosarcoma-risk commonly rises to Mendelian-levels in some dog breeds. This justifies caninized animal models and targeted clinical trials in pet dogs (e.g., using CDK4/6 and FGFR1/2 inhibitors).

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5531-6) contains supplementary material, which is available to authorized users.

Jaw osteosarcoma models in mice: first description

BACKGROUND

Osteosarcoma (OS) is the most common cancer of bone. Jaw osteosarcoma (JOS) is rare and it differs from other OS in terms of the time of occurrence (two decades later) and better survival. The aim of our work was to develop and characterize specific mouse models of JOS.

METHODS

Syngenic and xenogenic models of JOS were developed in mice using mouse (MOS-J) and human (HOS1544) osteosarcoma cell lines, respectively. An orthotopic patient-derived xenograft model (PDX) was also developed from a mandibular biopsy. These models were characterized at the histological and micro-CT imaging levels, as well as in terms of tumor growth and metastatic spread.

RESULTS

Homogeneous tumor growth was observed in both the HOS1544 and the MOS-J JOS models by injection of 0.25 × 10⁶ and 0.50 × 10⁶ tumor cells, respectively, at perimandibular sites. Histological characterization of the tumors revealed features consistent with high grade conventional osteosarcoma, and the micro-CT analysis revealed both osteogenic and osteolytic lesions. Early metastasis was encountered at day 14 in the xenogenic model, while there were no metastatic lesions in the syngenic model and in the PDX models.

CONCLUSION

We describe the first animal model of JOS and its potential use for therapeutic applications. This model needs to be compared with the usual long-bone osteosarcoma models to investigate potential differences in the bone microenvironment.

Tolerance to sustained activation of the cAMP/Creb pathway activity in osteoblastic cells is enabled by loss of p53

The loss of p53 function is a central event in the genesis of osteosarcoma (OS). How mutation of p53 enables OS development from osteoblastic lineage cells is poorly understood. We and others have reported a key role for elevated and persistent activation of the cAMP/PKA/Creb1 pathway in maintenance of OS. In view of the osteoblast lineage being the cell of origin of OS, we sought to determine how these pathways interact within the context of the normal osteoblast. Normal osteoblasts (p53 WT) rapidly underwent apoptosis in response to acute elevation of cAMP levels or activity, whereas p53-deficient osteoblasts tolerated this aberrant cAMP/Creb level and activity. Using the p53 activating small-molecule Nutlin-3a and cAMP/Creb1 activator forskolin, we addressed the question of how p53 responds to the activation of cAMP. We observed that p53 acts dominantly to protect cells from excessive cAMP accumulation. We identify a Creb1-Cbp complex that functions together with and interacts with p53. Finally, translating these results we find that a selective small-molecule inhibitor of the Creb1-Cbp interaction demonstrates selective toxicity to OS cells where this pathway is constitutively active. This highlights the cAMP/Creb axis as a potentially actionable therapeutic vulnerability in p53-deficient tumors such as OS. These results define a mechanism through which p53 protects normal osteoblasts from excessive or abnormal cAMP accumulation, which becomes fundamentally compromised in OS.