Characterizing the metabolic role of STAT3 in canine osteosarcoma

Signal transducer and activator of transcription 3 (STAT3) dysregulation has been characterized in canine OS, with previous data suggesting that constitutive STAT3 activation contributes to survival and proliferation in OS cell lines in vitro. Recently, the contribution of STAT3 to tumour metabolism has been described across several tumour histologies, and understanding the metabolic implications of STAT3 loss may elucidate novel therapeutic approaches with synergistic activity. The objective of this work was to characterize metabolic benchmarks associated with STAT3 loss in canine OS. STAT3 expression and activation was evaluated using western blotting in canine OS cell lines OSCA8 and Abrams. STAT3 was deleted from these OS cell lines using CRISPR-Cas9, and the effects on proliferation, invasion and metabolism (respirometry, intracellular lactate) were determined. Loss of STAT3 was associated with decreased basal and compensatory glycolysis in canine OS cell lines, without modulation of cellular proliferation. Loss of STAT3 also resulted in diminished invasive capacity in vitro. Interestingly, the absence of STAT3 did not impact sensitivity to doxorubicin in vitro. Our data demonstrate that loss of STAT3 modulates features of aerobic glycolysis in canine OS impacting capacities for cellular invasions, suggesting a role for this transcription factor in metastasis.

Pharmacokinetic Exposures Associated With Oral Administration of Sorafenib in Dogs With Spontaneous Tumors

Sorafenib is a multi-kinase small molecule inhibitor that targets serine/threonine and tyrosine kinases including the RAF kinase family, VEGFR-2, and PDGFR. The aim of this study was to evaluate the systemic pharmacokinetics of a previously defined tolerable oral dose of sorafenib in tumor-bearing dogs. Six client-owned dogs with a cytologic or histologic diagnosis of cancer were enrolled in this open-label, tolerability study. Dogs were administered sorafenib at an intended dose of 3 mg/kg and serum samples were obtained for analysis of sorafenib serum concentrations at 0, 1, 2, 6, 12, 24, 48, 72, 96, and 168 h post-drug administration. Median time to peak serum sorafenib concentration occurred at 4 h (range 2–12 h) resulting in an average serum concentration of 54.9 ± 33.5 ng/mL (118.2 ± 72.1 nM). Mean sorafenib levels declined by over 70% relative to peak serum concentrations by 24 h in all dogs, suggesting the value of at least twice daily administration. Doses of 3 mg/kg were well-tolerated and no patients in the study experienced adverse events that were attributable to sorafenib. Future trials in dogs with cancer are recommended at this dosing schedule to assess the effect of sorafenib administration on anti-tumor efficacy signals and relevant pharmacodynamic target modulation in vivo.

Development of an exosomal gene signature to detect residual disease in dogs with osteosarcoma using a novel xenograft platform and machine learning

Osteosarcoma has a guarded prognosis. A major hurdle in developing more effective osteosarcoma therapies is the lack of disease-specific biomarkers to predict risk, prognosis, or therapeutic response. Exosomes are secreted extracellular microvesicles emerging as powerful diagnostic tools. However, their clinical application is precluded by challenges in identifying disease-associated cargo from the vastly larger background of normal exosome cargo. We developed a method using canine osteosarcoma in mouse xenografts to distinguish tumor-derived from host-response exosomal messenger RNAs (mRNAs). The model allows for the identification of canine osteosarcoma-specific gene signatures by RNA sequencing and a species-differentiating bioinformatics pipeline. An osteosarcoma-associated signature consisting of five gene transcripts (SKA2, NEU1, PAF1, PSMG2, and NOB1) was validated in dogs with spontaneous osteosarcoma by real-time quantitative reverse transcription PCR (qRT-PCR), while a machine learning model assigned dogs into healthy or disease groups. Serum/plasma exosomes were isolated from 53 dogs in distinct clinical groups ("healthy", "osteosarcoma", "other bone tumor", or "non-neoplastic disease"). Pre-treatment samples from osteosarcoma cases were used as the training set, and a validation set from post-treatment samples was used for testing, classifying as "osteosarcoma detected" or "osteosarcoma-NOT detected". Dogs in a validation set whose post-treatment samples were classified as "osteosarcoma-NOT detected" had longer remissions, up to 15 months after treatment. In conclusion, we identified a gene signature predictive of molecular remissions with potential applications in the early detection and minimal residual disease settings. These results provide proof of concept for our discovery platform and its utilization in future studies to inform cancer risk, diagnosis, prognosis, and therapeutic response.

Serum IL-6 and MCP-1 concentrations in dogs with lymphoma before and after doxorubicin treatment as a potential marker of cellular senescence

BACKGROUND

Chemotherapy can induce cellular senescence and a secretory phenotype characterized by an increased expression of inflammatory cytokines, such as IL-6 and MCP-1. Increased IL-6 and MCP-1 serum concentrations have been documented in dogs with lymphoma, but no studies have evaluated the effects of chemotherapy on cytokine concentrations.

OBJECTIVES

To measure IL-6 and MCP-1 in 16 client-owned dogs with lymphoma, at baseline and before and after doxorubicin, as a potential marker for senescence and correlate cytokine concentrations with treatment response and toxicities.

METHODS

Serum IL-6 and MCP-1 concentrations at baseline, 0-h, 3-h, 6-h, 24-h and 1 week post doxorubicin were measured using a canine ELISA. We hypothesized that IL-6 and MCP-1 concentrations would increase following doxorubicin as a result of induction of cellular senescence.

RESULTS

IL-6 concentrations were unchanged from baseline to 0-h but significantly decreased 1 week post doxorubicin (p = 0.001) compared to 0-6 h (p = 0.045) and 24-h (p = 0.001) time points. MCP-1 concentrations significantly decreased from baseline to 0-h (p = 0.003). Compared to 0-6 h, MCP-1 concentrations transiently increased at 24-h (p = 0.001) and decreased at 1 week (p = 0.014) post doxorubicin. Changes in IL-6 and MCP-1 concentrations did not correlate with leukocyte count, response to treatment or chemotherapy toxicities.

CONCLUSIONS

Changes in IL-6 and MCP-1 concentrations did not support doxorubicin-induced cellular senescence or correlate with leukocyte count, response to treatment or chemotherapy toxicity. However, our results suggest that remission status and doxorubicin treatment may influence cytokine concentrations and future studies are warranted to investigate the role of these cytokines as biomarkers.

Characterization of receptor tyrosine kinase activation and biological activity of toceranib phosphate in canine urothelial carcinoma cell lines

Background

Urothelial carcinoma (UC) accounts for > 90% of canine tumors occurring in the urinary bladder. Toceranib phosphate (TOC) is a multi-target receptor tyrosine kinase (RTK) inhibitor that exhibits activity against members of the split kinase family of RTKs. The purpose of this study was to evaluate primary UC tumors and UC cell lines for the expression and activation of VEGFR2, PDGFRα, PDGFRβ, and KIT to assess whether dysregulation of these RTKs may contribute to the observed biological activity of TOC.

Results

Transcript for VEGFR2, PDGFRα, PDGFRβ, and KIT was detected in all UC tissue samples and UC cell lines. The Proteome Profiler™ Human Phospho-RTK Array Kit (R & D Systems) provided a platform to assess phosphorylation of 42 different RTKs in primary UC tumors and UC cell lines. Evidence of PDGFRα and PDGFRβ phosphorylation was present in only 11% or 33% of UC tumors, respectively, and 25% of UC cell lines. Treatment of UC cell lines with TOC had no significant impact on cell proliferation, including UC cell lines with evidence of PDGFRβ phosphorylation.

Conclusions

Phosphorylation of several key RTKs targeted by TOC is present in a small subset of primary UC tumors and UC cell lines, suggesting that these RTKs do not exist in a state of continuous activation. These data suggest that activation of RTKs targeted by TOC is present in a small subset of UC tumors and UC cell lines and that treatment with TOC at physiologically relevant concentrations has no direct anti-proliferative effect on UC cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03027-0.

Abstract 671: Development of an exosomal biomarker signature to detect minimal residual disease in dogs with osteosarcoma using a novel xenograft platform and machine learning

Osteosarcoma, the most common primary bone tumor in humans and dogs, has a guarded prognosis. A major hurdle in developing more effective osteosarcoma therapies is the lack of disease-specific biomarkers to predict risk, prognosis, or therapeutic response. Exosomes are secreted extracellular microvesicles emerging as powerful diagnostic tools. However, the wide clinical use of exosomes is precluded by the challenges in identifying disease-associated cargo from the vastly larger background of normal exosome cargo. We developed a method using canine osteosarcoma xenografts to distinguish tumor-derived exosome mRNAs and host-response mRNAs, allowing for identification of osteosarcoma-specific gene signatures, which were then validated in samples from dogs with osteosarcoma. A canine osteosarcoma-associated gene signature was developed using exosomes from mouse xenograft experiments and a species-aware bioinformatics pipeline. Validation of the gene signature in canine serum exosomes was done by qRT-PCR analysis. Machine learning algorithms assigned dogs into healthy or disease groups based on the qRT-PCR data. Dogs in a validation set of clinical osteosarcoma cases with post-treatment samples were classified as “osteosarcoma -detected” or “osteosarcoma - NOT detected”, and clinical outcome measures were compared. An osteosarcoma-associated signature consisting of five mRNAs (SKA2, NEU1, PAF1, PSMG2, and NOB1) was identified using our canine osteosarcoma xenograft model. Serum exosomes were isolated from 53 dogs in distinct clinical groups, including “healthy”, “osteosarcoma”, “other bone tumor”, or “non-neoplastic disease”. Dogs in a validation set whose post-treatment samples were classified as “osteosarcoma - NOT detected” had longer remissions than dogs classified as “osteosarcoma - detected” for up to 15 months after treatment. In conclusion, we identified a gene signature associated with canine osteosarcoma for the detection of minimal residual disease. This gene signature was validated by qRT-PCR with serum exosomes from canine patients with osteosarcoma, and used to train artificial intelligence. The test results were predictive of molecular remissions in dogs up to 15 months after initiating therapy, suggesting it will have applications in the early detection and minimal residual disease settings. This study combines a bioinformatics approach to biomarker discovery with machine learning to correctly identify osteosarcoma in canine patients. These results set the stage for future discoveries to inform cancer risk, diagnosis, prognosis, and response to therapy.

Citation Format: Kelly M. Makielski, Alicia J. Donnelly, Ali Khammanivong, Milcah C. Scott, Hirotaka Tomiyasu, John Garbe, Lauren J. Mills, Gary R. Cutter, Andrea Ortiz, Dana C. Galvan, Kristi Ward, Alexa N. Montoya, Brad A. Bryan, Joelle M. Fenger, William C. Kisseberth, Subbaya Subramanian, Jaime F. Modiano. Development of an exosomal biomarker signature to detect minimal residual disease in dogs with osteosarcoma using a novel xenograft platform and machine learning [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 671.

The selective inhibitor of nuclear export (SINE) verdinexor exhibits biologic activity against canine osteosarcoma cell lines

Verdinexor (KPT-335) is a novel orally bioavailable selective inhibitor of nuclear export (SINE) compound that inhibits the function of the nuclear export protein Exportin 1 (XPO1/CRM1). In the present study, we sought to characterize the expression of XPO1 in primary canine osteosarcoma (OS) tumour samples, OS cell lines and normal osteoblasts and evaluate the in vitro activity of verdinexor alone or in combination with doxorubicin. Canine OS cell lines and a subset of primary OS tumours showed increased XPO1 transcript and protein expression as compared with normal canine osteoblast cells. All canine OS cell lines exhibited dose-dependent growth inhibition and increased caspase 3,7 activity in response to low nanomolar concentrations of verdinexor (IC₅₀ concentrations ranging from 21 to 74 nM). Notably, growth inhibition of normal canine osteoblast cell lines treated with verdinexor was observed at high micromolar concentrations (IC₅₀  = 21 μM). The combination of verdinexor and doxorubicin resulted in potent inhibition of cell viability and demonstrated synergetic activity in three canine OS cell lines. Concordantly, OS cell lines showed increased γH2A.X foci following treatment with doxorubicin and recovery in verdinexor compared with cells treated with doxorubicin and recovered in normal media for 24 hours. These findings demonstrate that verdinexor has biologic activity against canine OS cell lines at physiologically relevant doses and suggest that XPO1 inhibition in combination with standard doxorubicin treatment offers promising potential for chemotherapeutic intervention in canine OS.

Plasma Cytokeratin 18 and fecal Alpha-1 Antitrypsin concentrations in dogs with osteosarcoma receiving carboplatin chemotherapy

Gastrointestinal (GI) toxicosis is a common side effect of cytotoxic chemotherapy treatment in humans and dogs. Measurement of cytokeratin 18 (CK18), an intracellular structural protein released during epithelial apoptosis, and Alpha1‐Antitrypsin (A1AT) in faeces provides a mechanism for evaluating damage to the intestinal mucosa secondary to cytotoxic chemotherapy. Our goal was to evaluate the clinical utility of plasma CK18 and faecal A1‐AT levels as non‐invasive biomarkers of cytotoxic chemotherapy induced GI toxicity. We conducted a prospective cohort study in dogs (N = 10) with osteosarcoma undergoing amputation followed by carboplatin chemotherapy. We hypothesized that plasma CK18 and faecal A1‐AT levels would increase following carboplatin administration due to drug‐induced GI epithelial damage/apoptosis, and that plasma CK18 and faecal A1‐AT levels would correlate with severity of GI toxicity. Mean baseline plasma CK18 concentration was variable amongst patients; however, CK18 concentration prior to carboplatin chemotherapy treatment was not significantly different from CK18 levels after treatment. There was significant intra and inter‐patient variability in mean faecal A1‐AT levels at baseline. Mean A1‐AT concentration did not change significantly from day 0 to day 21. Gastrointestinal toxicity was minimal; therefore, we were unable to determine the association of plasma CK18 and faecal A1‐AT concentrations with development of GI toxicosis. In this study population, plasma CK18 and faecal A1‐AT concentration were not clinically useful biomarkers for the detection of GI toxicosis secondary to carboplatin administration. Further prospective evaluation of CK18 and A1‐AT as biomarkers of drug‐induced GI toxicity is warranted in a larger cohort of dogs receiving cytotoxic chemotherapy.

AVMA clinical trial registration number: AAHSD004827.

Characterization of WWOX expression and function in canine mast cell tumors and malignant mast cell lines

Background

The WW domain-containing oxidoreductase (WWOX) tumor suppressor gene is frequently lost in a variety of solid and hematopoietic malignancies in humans. Dysregulation of WWOX has been implicated as playing a key role in tumor cell survival, DNA damage repair, and genomic stability. The purpose of this study was to characterize WWOX expression in spontaneous canine mast cell tumors (MCTs) and malignant cell lines and investigate the potential contribution of WWOX loss on malignant mast cell behavior.

Methods/results

WWOX expression is decreased in primary canine MCTs and malignant mast cell lines compared to normal canine bone marrow-cultured mast cells. In transformed canine mastocytoma cell lines, overexpression of WWOX or WWOX knockdown had no effect on mast cell viability. Inhibition of WWOX enhanced clonogenic survival following treatment with ionizing radiation in the C2 mast cell line. Lastly, immunohistochemistry for WWOX was performed using a canine MCT tissue microarray, demonstrating that WWOX staining intensity and percent of cells staining for WWOX is decreased in high-grade MCTs compared to low-grade MCTs.

Conclusions

These data suggest that WWOX expression is attenuated or lost in primary canine MCTs and malignant mast cell lines. Given the observed increase in clonogenic survival in WWOX-deficient C2 mast cells treated with ionizing radiation, further investigation of WWOX and its role in mediating the DNA damage response in malignant mast cells is warranted.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12917-020-02638-3.

Evaluation of microwave ablation for local treatment of dogs with distal radial osteosarcoma: A pilot study

OBJECTIVE

To evaluate the feasibility and safety of microwave ablation (MWA) as a modality to induce tumor necrosis within distal radial osteosarcoma (OSA).

STUDY DESIGN

Pilot study.

ANIMALS

Six client-owned dogs with distal radius OSA confirmed by cytological examination.

METHODS

Dogs underwent computed tomography for surgical planning before general anesthesia for fluoroscopy-guided ablation. Computed tomography was repeated 48 hours after MWA, before amputation. The ablated tumor was evaluated with histopathology.

RESULTS

Six dogs underwent MWA of distal radius OSA. A lower power setting (30 W) was selected for the first two dogs to avoid collateral soft tissue damage. The power was increased to 75 W for the last four dogs. The temperature was maintained between 45°C and 55°C (113 °F-131 °F) at the bone/soft tissue interface. Tumor necrosis varied between 30% and 90% (median, 55%) according to histopathology. No intraoperative or periprocedural complications were observed.

CONCLUSION

Microwave ablation induced variable tumor necrosis and did not induce immediate postablation complications in these six dogs with distal radius OSA.

CLINICAL SIGNIFICANCE

These results justify further evaluation of MWA as a potential modality to treat primary bone lesions in dogs.

S100A4 mRNA-protein relationship uncovered by measurement noise reduction

Intrinsic biological fluctuation and/or measurement error can obscure the association of gene expression patterns between RNA and protein levels. Appropriate normalization of reverse-transcription quantitative PCR (RT-qPCR) data can reduce technical noise in transcript measurement, thus uncovering such relationships. The accuracy of gene expression measurement is often challenged in the context of cancer due to the genetic instability and "splicing weakness" involved. Here, we sequenced the poly(A) cancer transcriptome of canine osteosarcoma using mRNA-Seq. Expressed sequences were resolved at the level of two consecutive exons to enable the design of exon-border spanning RT-qPCR assays and ranked for stability based on the coefficient of variation (CV). Using the same template type for RT-qPCR validation, i.e. poly(A) RNA, avoided skewing of stability assessment by circular RNAs (circRNAs) and/or rRNA deregulation. The strength of the relationship between mRNA expression of the tumour marker S100A4 and its proportion score of quantitative immunohistochemistry (qIHC) was introduced as an experimental readout to fine-tune the normalization choice. Together with the essential logit transformation of qIHC scores, this approach reduced the noise of measurement as demonstrated by uncovering a highly significant, strong association between mRNA and protein expressions of S100A4 (Spearman's coefficient ρ = 0.72 (p = 0.006)). KEY MESSAGES: • RNA-seq identifies stable pairs of consecutive exons in a heterogeneous tumour. • Poly(A) RNA templates for RT-qPCR avoid bias from circRNA and rRNA deregulation. • HNRNPL is stably expressed across various cancer tissues and osteosarcoma. • Logit transformed qIHC score better associates with mRNA amount. • Quantification of minor S100A4 mRNA species requires poly(A) RNA templates and dPCR.

Radiation-induced sarcoma in a cat following hypofractionated, palliative intent radiation therapy for large-cell lymphoma

Case summary

A 5-year-old female spayed domestic shorthair cat was presented with a 4.5 × 3 cm ulcerated cutaneous mass on the nasal bridge with extension into the nasal cavity. Tissue biopsy was obtained and a diagnosis of large-cell lymphoma was confirmed on histopathology. The cat was started on prednisolone and injectable chemotherapy; however, only a partial response was observed. A CT scan revealed a highly infiltrative mass with extensive subcutaneous involvement, extending into the nasal cavity, resulting in lysis of numerous nasal and facial bones. The cat received hypofractionated, palliative intent radiation therapy (four fractions of 8 Gray) and a complete clinical response was achieved. Nine months after radiation therapy, minimal residual intranasal disease was observed on advanced imaging. Sixty-nine months after the completion of radiotherapy, a mass was observed dorsal to the right eye within the previous radiation field. CT scan revealed a mass associated with the right frontal sinus with extension throughout the nasal cavity and facial bones. Histopathology was consistent with a moderately differentiated sarcoma. Seventy-one months post-radiation therapy, the cat developed neurologic clinical signs and was humanely euthanized. Radiation-induced sarcoma was suspected based on human criteria, which included history of irradiation and tumor development within the irradiated field, a latent period after irradiation prior to the development of the second tumor and histopathologic confirmation of a different malignant neoplasm at the irradiated site.

Relevance and novel information

To our knowledge, this is the first report of a malignant radiation-induced sarcoma in a cat. Based on this case, radiation-induced sarcomas should be considered as a late-term side effect associated with radiation therapy in cats.

Abstract B081: Regulation and function of monocarboxylate transporters in osteosarcoma

Background: Osteosarcoma (OS), the most common malignant bone tumor in humans and dogs, shares several features in both species including clinical presentation and molecular alterations. Despite numerous efforts there have been no improvements in outcome: 30% of people and 90% of dogs still die of metastasis. In both species, macroscopic metastasis exhibits inherent resistance to multiple agents (kinase inhibitors, chemotherapy, immunotherapy, among others). In both dogs and humans, the OS genomes exhibit low somatic mutational load and no clear molecular drivers. These data, along with a history of failed clinical trials suggest that contemporary approaches to therapeutic advancement (kinase inhibitors, immune checkpoint blockade) will likely have limited clinical impact, necessitating therapeutic innovation. Monocarboxylate transporters (MCTs) move lactic acid across the plasma membrane, providing a mechanism for tumor cells to meet their bioenergetic needs in a variety of limiting microenvironments. The objective of this work is credential MCTs (MCT1/MCT4) as therapeutic targets in OS and investigate mechanisms of synthetic lethality. Methods: STAT3, MCT1 and MCT4 expression and function were modulated in canine and human OS cell lines using a combination of CRISPR/cas9 techniques and pharmacologic agents (AZD3965, AstraZeneca; syrosingopine, Sigma Aldrich). Western blotting, luciferase reporter assays and chromatin immunoprecipitation (ChIP) were used to investigate the transcriptional regulation of MCT1/MCT4. The metabolic effects of STAT3 and MCT inhibition were investigated through measurement of lactate (Lactate-Glo, Promega) and respirometry (Seahorse XFe96 extracellular flux analyzer), while cell proliferation and invasion were evaluated using sulforhodamine B and Matrigel invasion assays. Results: MCT1/MCT4 and were found to be expressed in all OS cell lines, although at variable levels. Following knockdown of STAT3, MCT4 expression was downregulated in several OS cell lines. ChIP assays confirm enrichment of STAT3 and FOXM1 at the MCT4 promoter, and this was confirmed in STAT3 deficient OS lines that exhibited decreased MCT4-dependent luciferase reporter activity. The absence of MCT1 or MCT4 was associated with decreased basal and compensatory glycolysis and increased intracellular lactate. In addition, decreased proliferation and invasive capacity were noted concurrent with MCT loss. Dual MCT1/MCT4 inhibition exhibited synergy with doxorubicin, as determined by a combination index < 1. Conclusions: Loss of MCT1 or MCT4 function in OS cells decreases basal and compensatory glycolysis, cellular proliferation and invasive capacity. MCT4 is a direct transcriptional target of STAT3 and FOXM1, both of which exhibit constitutive activation in OS, supporting a link between MCT4/STAT3/FOXM1 and aerobic glycolysis. Despite promising results in vitro, rational drug combinations may be needed to maximize the effect of MCT1/4 inhibition. Together these studies will create a blueprint for clinical translational with the goal of optimizing strategies in dogs with OS prior to human trials.

Citation Format: Heather L. Gardner, Joelle M. Fenger, Cheryl A. London. Regulation and function of monocarboxylate transporters in osteosarcoma [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B081. doi:10.1158/1535-7163.TARG-19-B081

MicroRNA expression in the cerebrospinal fluid of dogs with and without cervical spondylomyelopathy

BACKGROUND

Osseous-associated cervical spondylomyelopathy (OA-CSM) is a common condition of the cervical vertebral column that affects giant dog breeds. MicroRNAs (miRNAs) are small RNAs that regulate gene expression, and recent data suggest that circulating miRNAs present in biological fluids may serve as potential biomarkers for disease. The miRNA profiles of cerebrospinal fluid (CSF) from healthy dogs and dogs clinically affected by OA-CSM have not been described.

OBJECTIVE

To characterize the expression levels of miRNAs present in the CSF of normal Great Danes and identify differentially expressed miRNAs in the CSF of Great Danes clinically affected with OA-CSM.

ANIMALS

Client-owned dogs: 12 control, 12 OA-CSM affected.

METHODS

Cerebrospinal fluid samples were collected prospectively. MicroRNA expression was evaluated using the NanoString nCounter platform and quantitative real-time PCR.

RESULTS

We identified 8 miRNAs with significant differential expression. MiR-299-5p and miR-765 had increased expression levels in the CSF of OA-CSM-affected dogs, whereas miR-494, miR-612, miR-302-d, miR-4531, miR-4455, and miR-6721-5p had decreased expression levels in OA-CSM affected dogs compared to clinically normal dogs. Quantitative real-time PCR was performed to validate the expression levels of 2 miRNAs (miR-494 and miR-612), and we found a 1.5-fold increase in miR-494 expression and a 1.2-fold decrease in miR-612 in the CSF of the OA-CSM affected group (P = .41 and .89, respectively).

CONCLUSIONS AND CLINICAL IMPORTANCE

Data generated from our study represent an initial characterization of the miRNA profile of normal canine CSF and suggest that a distinct CSF miRNA expression profile is associated with OA-CSM.

miR-133a function in the pathogenesis of dedifferentiated liposarcoma

Background

Sarcomas are malignant heterogeneous tumors of mesenchymal derivation. Dedifferentiated liposarcoma (DDLPS) is aggressive with recurrence in 80% and metastasis in 20% of patients. We previously found that miR-133a was significantly underexpressed in liposarcoma tissues. As this miRNA has recently been shown to be a tumor suppressor in many cancers, the objective of this study was to characterize the biological and molecular consequences of miR-133a underexpression in DDLPS.

Methods

Real-time PCR was used to evaluate expression levels of miR-133a in human DDLPS tissue, normal fat tissue, and human DDLPS cell lines. DDLPS cells were stably transduced with miR-133a vector to assess the effects in vitro on proliferation, cell cycle, cell death, migration, and metabolism. A Seahorse Bioanalyzer system was also used to assess metabolism in vivo by measuring glycolysis and oxidative phosphorylation (OXPHOS) in subcutaneous xenograft tumors from immunocompromised mice.

Results

miR-133a expression was significantly decreased in human DDLPS tissue and cell lines. Enforced expression of miR-133a decreased cell proliferation, impacted cell cycle progression kinetics, decreased glycolysis, and increased OXPHOS. There was no significant effect on cell death or migration. Using an in vivo xenograft mouse study, we showed that tumors with increased miR-133a expression had no difference in tumor growth compared to control, but did exhibit an increase in OXPHOS metabolic respiration.

Conclusions

Based on our collective findings, we propose that in DDPLS, loss of miR-133a induces a metabolic shift due to a reduction in oxidative metabolism favoring a Warburg effect in DDLPS tumors, but this regulation on metabolism was not sufficient to affect DDPLS.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0583-2) contains supplementary material, which is available to authorized users.

Classical NF-κB Metabolically Reprograms Sarcoma Cells Through Regulation of Hexokinase 2

BACKGROUND

Metabolic reprogramming has emerged as a cancer hallmark, and one of the well-known cancer-associated metabolic alterations is the increase in the rate of glycolysis. Recent reports have shown that both the classical and alternative signaling pathways of nuclear factor κB (NF-κB) play important roles in controlling the metabolic profiles of normal cells and cancer cells. However, how these signaling pathways affect the metabolism of sarcomas, specifically rhabdomyosarcoma (RMS) and osteosarcoma (OS), has not been characterized.

METHODS

Classical NF-κB activity was inhibited through overexpression of the IκBα super repressor of NF-κB in RMS and OS cells. Global gene expression analysis was performed using Affymetrix GeneChip Human Transcriptome Array 2.0, and data were interpreted using gene set enrichment analysis. Seahorse Bioscience XFe24 was used to analyze oxygen consumption rate as a measure of aerobic respiration.

RESULTS

Inhibition of classical NF-κB activity in sarcoma cell lines restored alternative signaling as well as an increased oxidative respiratory metabolic phenotype in vitro. In addition, microarray analysis indicated that inhibition of NF-κB in sarcoma cells reduced glycolysis. We showed that a glycolytic gene, hexokinase (HK) 2, is a direct NF-κB transcriptional target. Knockdown of HK2 shifted the metabolic profile in sarcoma cells away from aerobic glycolysis, and re-expression of HK2 rescued the metabolic shift induced by inhibition of NF-κB activity in OS cells.

CONCLUSION

These findings suggest that classical signaling of NF-κB plays a crucial role in the metabolic profile of pediatric sarcomas potentially through the regulation of HK2.

Osteosarcoma: Accelerating Progress Makes for a Hopeful Future

Patients who develop osteosarcoma in 2017 receive treatment that remains essentially unchanged since the 1970s. Outcomes likewise remain largely unimproved. Large, collaborative, multinational efforts to improve therapy have evaluated strategies leveraging both cytotoxic intensification and immunomodulatory agents. While these have confirmed our capacity to conduct such trials, results have proved largely disappointing. This has motivated efforts to focus on the basic biology of osteosarcoma, where understanding remains poor but has improved significantly. Recent advances have identified characteristic genetic features of osteosarcoma, including profound chromosomal disruption, marked patient-patient heterogeneity, and a paucity of recurrent mutations. Analyses suggest genesis in early catastrophic genetic events, although the nature of the inciting events remains unclear. While p53 and Rb inactivation occurs in most osteosarcomas, the landscape of associated driver mutations has proved extensive. Few mutations recur with high frequency, though patterns continue to emerge that suggest recurrent alterations within specific pathways. Biological pathways implicated in osteosarcoma biology through genetic and other preclinical studies include PI3K/mTOR, WNT/βcatenin, TGFβ, RANKL/NF-κB, and IGF. Unfortunately, clinical studies evaluating targeted agents have to date yielded disappointing results, as have studies examining modern immunotherapeutics. It remains unclear whether this pattern of clinical failures exposes inadequacies of our preclinical models, unrealistic expectations for single-agent responses in heavily pretreated patients, or biology less relevant than suggested. Nearly all patients who succumb to osteosarcoma develop lung metastases, which exhibit marked chemoresistance. Much scientific effort has recently sought to enhance our mechanistic understanding of metastasis biology. This research has potential to reveal novel targets for preventing and treating metastasis and for uncovering key vulnerabilities of osteosarcoma cells. Efforts to implement drug development strategies that leverage clinical studies in veterinary patients have potential to accelerate the translation of novel experimental regimens toward human studies. These could reduce costs and development timelines, prioritize agents, and refine regimens prior to human clinical trials. The rise of philanthropic groups focused on osteosarcoma has enhanced cross-disciplinary and cross-institutional focus and provided much needed resources. Transformative new therapies will likely arise from collaborative, interdisciplinary efforts that extend our understanding of osteosarcoma's most basic inner workings.

ΔNp63 mediates cellular survival and metastasis in canine osteosarcoma

p63 is a structural homolog within the 53 family encoding two isoforms, ΔNp63 and TAp63. The oncogenic activity of ΔNp63 has been demonstrated in multiple cancers, however the underlying mechanisms that contribute to tumorigenesis are poorly characterized. Osteosarcoma (OSA) is the most common primary bone tumor in dogs, exhibiting clinical behavior and molecular biology essentially identical to its human counterpart. The purpose of this study was to evaluate the potential contribution of ΔNp63 to the biology of canine OSA. As demonstrated by qRT-PCR, nearly all canine OSA cell lines and tissues overexpressed ΔNp63 relative to normal control osteoblasts. Inhibition of ΔNp63 by RNAi selectively induced apoptosis in the OSA cell lines overexpressing ΔNp63. Knockdown of ΔNp63 upregulated expression of the proapoptotic Bcl-2 family members Puma and Noxa independent of p53. However the effects of ΔNp63 required transactivating isoforms of p73, suggesting that ΔNp63 promotes survival in OSA by repressing p73-dependent apoptosis. In addition, ΔNp63 modulated angiogenesis and invasion through its effects on VEGF-A and IL-8 expression, and STAT3 phosphorylation. Lastly, the capacity of canine OSA cell lines to form pulmonary metastasis was directly related to expression levels of ΔNp63 in a murine model of metastatic OSA. Together, these data demonstrate that ΔNp63 inhibits apoptosis and promotes metastasis, supporting continued evaluation of this oncogene as a therapeutic target in both human and canine OSA.

MiR-34a regulates the invasive capacity of canine osteosarcoma cell lines

BACKGROUND

Osteosarcoma (OSA) is the most common bone tumor in children and dogs; however, no substantial improvement in clinical outcome has occurred in either species over the past 30 years. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and play a fundamental role in cancer. The purpose of this study was to investigate the potential contribution of miR-34a loss to the biology of canine OSA, a well-established spontaneous model of the human disease.

METHODOLOGY AND PRINCIPAL FINDINGS

RT-qPCR demonstrated that miR-34a expression levels were significantly reduced in primary canine OSA tumors and canine OSA cell lines as compared to normal canine osteoblasts. In canine OSA cell lines stably transduced with empty vector or pre-miR-34a lentiviral constructs, overexpression of miR-34a inhibited cellular invasion and migration but had no effect on cell proliferation or cell cycle distribution. Transcriptional profiling of canine OSA8 cells possessing enforced miR-34a expression demonstrated dysregulation of numerous genes, including significant down-regulation of multiple putative targets of miR-34a. Moreover, gene ontology analysis of down-regulated miR-34a target genes showed enrichment of several biological processes related to cell invasion and motility. Lastly, we validated changes in miR-34a putative target gene expression, including decreased expression of KLF4, SEM3A, and VEGFA transcripts in canine OSA cells overexpressing miR-34a and identified KLF4 and VEGFA as direct target genes of miR-34a. Concordant with these data, primary canine OSA tumor tissues demonstrated increased expression levels of putative miR-34a target genes.

CONCLUSIONS

These data demonstrate that miR-34a contributes to invasion and migration in canine OSA cells and suggest that loss of miR-34a may promote a pattern of gene expression contributing to the metastatic phenotype in canine OSA.

Abstract 5412: Expression and inhibition of monocarboxylate transporters in canine osteosarcoma

Background: A distinguishing feature of cancer cells is their ability to undergo aerobic glycolysis, even in the presence of oxygen. This process generates lactic acid, which must be removed from the cell in order to maintain proliferation and survival. Monocarboxylate transporters (MCTs) move lactic acid across the plasma membrane, providing a mechanism for tumor cells to meet their bioenergetic needs during glycolysis in a variety of limiting microenvironments. The objective of this work is to determine the biologic effects of modulating cellular metabolism through inhibition of MCT1 and MCT4 in canine osteosarcoma (OS), a well-established spontaneous large animal model of the human disease.

Methods: MCT1 and MCT4 expression was assessed in canine OS cell lines using qRT-PCR and western blotting. Immunohistochemistry and qRT-PCR were performed to determine relative MCT1 and MCT4 expression in primary canine OS tissues. The effects of small molecule inhibitors (NGY066 and NGY008) and shRNA approaches targeting MCT1 and MCT4 on proliferation and survival of canine OS were examined using the CyQUANT Cell Proliferation and Caspase-3/7 assays, respectively. The impact of MCT1/4 inhibition on cellular oxygen consumption was evaluated using the Seahorse Cell Mito Stress Test. Lastly, potential synergistic effects of combining metformin and doxorubicin with MCT1/4 inhibition in canine OS cell lines were investigated using the CyQUANT Assay.

Results: We found that while both MCT1 and MCT4 are expressed in canine OS lines and tissues, MCT1 is expressed at higher levels relative to MCT4 in the cell lines. Small molecule inhibitors directed against MCT1 and MCT4 did not significantly inhibit cell proliferation or induce apoptosis even in the presence of limiting cell culture conditions. Maximal respiratory capacity was not increased in canine OS cell lines following inhibition of MCT1 and MCT4 function. However, synergistic anti-proliferative activity was observed when OS cells were treated with doxorubicin or metformin in the presence of MCT1 and MCT4 inhibitors.

Conclusions: MCT1 and MCT4 are expressed in canine OS, and therefore represent a good model to evaluate the therapeutic potential of manipulating lactic acid transport. Importantly, drug combinations with synergistic activity may be necessary to realize the full potential of MCT1/4 inhibition.

Citation Format: Heather L. Gardner, Joelle M. Fenger, Vincent P. Sandanayaka, Cheryl A. London. Expression and inhibition of monocarboxylate transporters in canine osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5412. doi:10.1158/1538-7445.AM2017-5412

Abstract 3043: A novel Cpa3-Cre; miR-9 fl/fl mouse reveals a functional role for miR-9 in promoting mast cell invasion via up-regulation of CMA1

Introduction: Our laboratory previously demonstrated that miR-9 promotes the invasive properties of normal and malignant mast cells and that overexpression of miR-9 is associated with spontaneous metastasis in canine mast cell tumors (MCTs), a well-established large animal model of malignant mast cell disease. The purpose of this study was to further investigate the biologic effect and mechanisms by which mir-9 enhances normal mast cell invasion.

Methods: Bone marrow-derived mast cells (BMMCs) were generated from Cpa3-Cre; miR-9Δfl/Δfl, and Cpa3-Cre; miR-9Δfl/Δfl mice and Taqman miRNA assays were used to quantify mature miR-9 expression. BMMCs were evaluated for differences in proliferative capacity, the ability to migrate through Matrigel, sensitivity to degranulation, and the expression and release of growth factor expression and release following chemical stimulation. RNA sequencing was performed by the OSUCCC Genomics Resource and changes in protein and mRNA expression were validated with Western blotting and quantitative PCR.

Results and Conclusions: We generated a transgenic mouse carrying a floxed STOP-miR-9 transgene (miR-9Δfl/Δfl) in which expression of miR-9 occurs only after Cre-mediated recombination and crossed these mice with Cpa3-Cre mice which express Cre recombinase under the control of the carboxypeptidase A3 (Cpa3) promoter, restricting expression of miR-9 to mast cells and basophils. Bone marrow-derived mast cells (BMMCs) derived from Cpa3-Cre;miR-9Δfl/Δfl mice significantly enhanced the invasive phenotype of mast cells. Moreover, the enforced expression of miR-9 in BMMCs markedly changed the production and release of cytokine and growth factors in response to chemical stimulation, including substantial up-regulation of IL-4, IL-13, and GM-CSF transcript and enhanced TGF-β1 release. RNA sequencing revealed a unique transcriptional profile associated with miR-9 over-expression in the Cpa3-Cre;miR-9Δfl/Δfl derived BMMCs and identified increased expression of several mast cell-restricted proteases involved in extracellular matrix and tissue remodeling including CMA1 and MCP-6. Furthermore, transduction of Cpa3-Cre;miR-9Δfl/Δfl derived BMMCs with CMA1 shRNA abrogated miR-9-dependent mast cell invasion. Studies are underway to investigate the regulatory pathway mediated by miR-9 that contributes to CMA1 up-regulation and promotes the invasive phenotype. In summary, these data provide evidence supporting a critical role for miR-9 in mast cell invasion and suggest that dysregulation of miR-9 may contribute to pathologic conditions involving mast cell-mediated tissue remodeling.

Citation Format: Joelle M. Fenger, Feng Xu, Xaioli Zhang, Peter Y. Yu, Misty D. Bear, Shanice L. Reynolds, Michael L. Pennell, Vincenzo Coppola, William C. Kisseberth, Stephen J. Galli, Cheryl A. London. A novel Cpa3-Cre; miR-9fl/fl mouse reveals a functional role for miR-9 in promoting mast cell invasion via up-regulation of CMA1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3043. doi:10.1158/1538-7445.AM2017-3043

MiR-9 is overexpressed in spontaneous canine osteosarcoma and promotes a metastatic phenotype including invasion and migration in osteoblasts and osteosarcoma cell lines

Background

MicroRNAs (miRNAs) regulate the expression of networks of genes and their dysregulation is well documented in human malignancies; however, limited information exists regarding the impact of miRNAs on the development and progression of osteosarcoma (OS). Canine OS exhibits clinical and molecular features that closely resemble the corresponding human disease and it is considered a well-established spontaneous animal model to study OS biology. The purpose of this study was to investigate miRNA dysregulation in canine OS.

Methods

We evaluated miRNA expression in primary canine OS tumors and normal canine osteoblast cells using the nanoString nCounter system. Quantitative PCR was used to validate the nanoString findings and to assess miR-9 expression in canine OS tumors, OS cell lines, and normal osteoblasts. Canine osteoblasts and OS cell lines were stably transduced with pre-miR-9 or anti-miR-9 lentiviral constructs to determine the consequences of miR-9 on cell proliferation, apoptosis, invasion and migration. Proteomic and gene expression profiling of normal canine osteoblasts with enforced miR-9 expression was performed using 2D-DIGE/tandem mass spectrometry and RNA sequencing and changes in protein and mRNA expression were validated with Western blotting and quantitative PCR. OS cell lines were transduced with gelsolin (GSN) shRNAs to investigate the impact of GSN knockdown on OS cell invasion.

Results

We identified a unique miRNA signature associated with primary canine OS and identified miR-9 as being significantly overexpressed in canine OS tumors and cell lines compared to normal osteoblasts. Additionally, high miR-9 expression was demonstrated in tumor-specific tissue obtained from primary OS tumors. In normal osteoblasts and OS cell lines transduced with miR-9 lentivirus, enhanced invasion and migration were observed, but miR-9 did not affect cell proliferation or apoptosis. Proteomic and transcriptional profiling of normal canine osteoblasts overexpressing miR-9 identified alterations in numerous genes, including upregulation of GSN, an actin filament-severing protein involved in cytoskeletal remodeling. Lastly, stable downregulation of miR-9 in OS cell lines reduced GSN expression with a concomitant decrease in cell invasion and migration; concordantly, cells transduced with GSN shRNA demonstrated decreased invasive properties.

Conclusions

Our findings demonstrate that miR-9 promotes a metastatic phenotype in normal canine osteoblasts and malignant OS cell lines, and that this is mediated in part by enhanced GSN expression. As such, miR-9 represents a novel target for therapeutic intervention in OS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2837-5) contains supplementary material, which is available to authorized users.

Dogs as a Model for Cancer

Spontaneous cancers in client-owned dogs closely recapitulate their human counterparts with respect to clinical presentation, histological features, molecular profiles, and response and resistance to therapy, as well as the evolution of drug-resistant metastases. In several instances the incorporation of dogs with cancer into the preclinical development path of cancer therapeutics has influenced outcome by helping to establish pharmacokinetic/pharmacodynamics relationships, dose/regimen, expected clinical toxicities, and ultimately the potential for biologic activity. As our understanding regarding the molecular drivers of canine cancers has improved, unique opportunities have emerged to leverage this spontaneous model to better guide cancer drug development so that therapies likely to fail are eliminated earlier and therapies with true potential are optimized prior to human studies. Both pets and people benefit from this approach, as it provides dogs with access to cutting-edge cancer treatments and helps to insure that people are given treatments more likely to succeed.

Canine osteosarcoma: a naturally occurring disease to inform pediatric oncology

Osteosarcoma (OSA) is the most common form of malignant bone cancer in children and dogs, although the disease occurs in dogs approximately 10 times more frequently than in people. Multidrug chemotherapy and aggressive surgical techniques have improved survival; however, new therapies for OSA are critical, as little improvement in survival times has been achieved in either dogs or people over the past 15 years, even with significant efforts directed at the incorporation of novel therapeutic approaches. Both clinical and molecular evidence suggests that human and canine OSA share many key features, including tumor location, presence of microscopic metastatic disease at diagnosis, development of chemotherapy-resistant metastases, and altered expression/activation of several proteins (e.g. Met, ezrin, phosphatase and tensin homolog, signal transducer and activator of transcription 3), and p53 mutations, among others. Additionally, canine and pediatric OSA exhibit overlapping transcriptional profiles and shared DNA copy number aberrations, supporting the notion that these diseases are similar at the molecular level. This review will discuss the similarities between pediatric and canine OSA with regard to histology, biologic behavior, and molecular genetic alterations that indicate canine OSA is a relevant, spontaneous, large animal model of the pediatric disease and outline how the study of naturally occurring OSA in dogs will offer additional insights into the biology and future treatment of this disease in both children and dogs.

Abstract 540: Characterization of miR-9 expression and activation in canine osteosarcoma

Introduction: Osteosarcoma (OSA) is the most common malignant bone tumor in children and dogs. Despite aggressive treatment, no improvement in survival times has been achieved in the past 15 years with 40% of children and 90% of dogs still dying from disease. MicroRNAs (miRs) are non-protein coding RNAs that have been implicated as having a fundamental role in cancer. We analyzed primary canine OSA tumors and canine osteoblasts for miR expression and found miR-9 to be highly expressed in OSA tumors and cell lines as compared to normal osteoblasts. We hypothesize that miR-9 overexpression generates a pattern of gene dysregulation that contributes to the pathogenesis of OSA.

Methodology: Canine bone marrow derived stem cells were differentiated in vitro into osteoblasts and expression of bone-specific markers (ALP, OP, BMP-2) was detected by immunocytochemistry or RT-PCR. MiR expression profiling was performed on 48 primary canine OSA tumors and 3 osteoblast cultures using the NanoString nCounter human microRNA Expression Assay. Taqman miRNA assays were used to measure miR-9 expression in primary canine OSA tumors, OSA cell lines, primary osteoblast cultures, and commercially available osteoblast cell lines. Canine OSA16 and osteoblast cell lines were transduced with lentiviral pre-miR-9 or empty control vector constructs and cells were evaluated for differences in proliferative capacity, apoptosis, and the ability to migrate through Matrigel.

Results and Conclusions: We identified 84 miRs (p ≤ 0.01) differentially expressed in primary canine OSA tumors compared to canine osteoblasts. MiR-9 was highly expressed in primary OSA tumors and cell lines as compared to normal osteoblast cell lines or primary cultures. Canine OSA16 and normal osteoblast cell lines, which express low levels of miR-9 were transduced with miR-9 lentiviral constructs resulting in high levels of miR-9 expression. Overexpression of miR-9 did not effect cell proliferation or apoptosis, but enhanced invasion through matrigel in both malignant OSA cells and normal osteoblasts. Our findings suggest that miR-9 may play an important role in regulating OSA cell invasion and suggest that overexpression of miR-9 in vivo may promote metastasis in canine OSA. Transcriptional and proteomic profiling of osteoblasts overexpressing miR-9 is underway to define key differences in mRNA and protein expression and phosphorylation that may contribute to the metastatic phenotype in canine OSA. This work will provide significant new data regarding the impact of miR-9 on molecular pathways in OSA, thereby laying the foundation for the development and testing of novel therapeutics in both children and dogs affected by this disease.

Citation Format: Joelle M. Fenger, Jason I. Couto, Misty D. Bear, Stefano Volinia, Jaime F. Modiano, Matthew Breen, Cheryl A. London, William C. Kisseberth. Characterization of miR-9 expression and activation in canine osteosarcoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 540. doi:10.1158/1538-7445.AM2014-540

Overexpression of miR-9 in mast cells is associated with invasive behavior and spontaneous metastasis

Background

While microRNA (miRNA) expression is known to be altered in a variety of human malignancies contributing to cancer development and progression, the potential role of miRNA dysregulation in malignant mast cell disease has not been previously explored. The purpose of this study was to investigate the potential contribution of miRNA dysregulation to the biology of canine mast cell tumors (MCTs), a well-established spontaneous model of malignant mast cell disease.

Methods

We evaluated the miRNA expression profiles from biologically low-grade and biologically high-grade primary canine MCTs using real-time PCR-based TaqMan Low Density miRNA Arrays and performed real-time PCR to evaluate miR-9 expression in primary canine MCTs, malignant mast cell lines, and normal bone marrow-derived mast cells (BMMCs). Mouse mast cell lines and BMMCs were transduced with empty or pre-miR-9 expressing lentiviral constructs and cell proliferation, caspase 3/7 activity, and invasion were assessed. Transcriptional profiling of cells overexpressing miR-9 was performed using Affymetrix GeneChip Mouse Gene 2.0 ST arrays and real-time PCR was performed to validate changes in mRNA expression.

Results

Our data demonstrate that unique miRNA expression profiles correlate with the biological behavior of primary canine MCTs and that miR-9 expression is increased in biologically high grade canine MCTs and malignant cell lines compared to biologically low grade tumors and normal canine BMMCs. In transformed mouse malignant mast cell lines expressing either wild-type (C57) or activating (P815) KIT mutations and mouse BMMCs, miR-9 overexpression significantly enhanced invasion but had no effect on cell proliferation or apoptosis. Transcriptional profiling of normal mouse BMMCs and P815 cells possessing enforced miR-9 expression demonstrated dysregulation of several genes, including upregulation of CMA1, a protease involved in activation of matrix metalloproteases and extracellular matrix remodeling.

Conclusions

Our findings demonstrate that unique miRNA expression profiles correlate with the biological behavior of canine MCTs. Furthermore, dysregulation of miR-9 is associated with MCT metastasis potentially through the induction of an invasive phenotype, identifying a potentially novel pathway for therapeutic intervention.

Abstract 184: Breed-associated differential microRNA expression in canine osteosarcoma

Introduction: MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression. miRNAs are dysregulated in cancer, suggesting they play a role in tumorigenesis. Osteosarcoma (OSA) is the most common bone tumor in dogs, however, little is known regarding mechanisms underlying malignant transformation in these tumors. Breeds such as Rottweilers and Greyhounds are at higher risk for developing OSA, suggesting that heritable factors play a role in this disease. We hypothesize that dysregulation of miRNAs in canine OSA is associated with specific breeds. Methods: RNA was isolated by the Trizol (Invitrogen) method from a panel of seven normal canine tissues and 48 primary canine OSA tumors from Greyhound, Golden Retriever, Rottweiler, and mixed breed dogs. miRNA expression was analyzed using the NanoString nCounter human microRNA Expression Assay, interrogating the expression of 752 human miRNAs; 168 of whose mature sequences are 100% conserved between human and dog (Sanger miRBase V15). Samples were hybridized to reporter CodeSets, processed on the nCounter prep station, and scanned with the nCounter Digital Analyzer. Nanominer software was used to perform data normalization. Real time PCR was performed using Applied Biosystems Taqman miRNA assays. Normalization was performed with U6 snRNA and miRNA expression was calculated utilizing the comparative Ct method. P-values of <0.05 were considered statistically significant. For reverse-transcription PCR reactions, cDNA was prepared using Superscript III (Invitrogen) and PCR was performed using ThermoPrime Taq Polymerase (ThermoScientific). Results: miRNA profiling of normal canine tissues revealed tissue-specific miRNA expression signatures. Real time PCR validation of tissue-specific miRNAs validated the use of the NanoString nCounter Assay as a platform for evaluating miRNA expression in canine tissues. Supervised hierarchical cluster analysis revealed distinct breed-associated miRNA expression signatures in canine OSA. 189 miRNAs were differentially expressed in Greyhound, Rottweiler, Golden Retriever, and mixed breed tumors (p<0.01). In an expanded cohort of Greyhound and Rottweiler tumors, real time PCR demonstrated that miR-494 is highly expressed in Rottweiler OSA as compared to Greyhound OSA (p<0.05) or normal canine osteoblasts from various dog breeds, including one Rottweiler. Studies are underway to assess the biological consequences of miR-494 overexpression in normal canine osteoblasts and OSA cell lines. Small RNA sequencing of these OSA samples using the Applied Biosystems SOLiD 4 sequencing platform is being performed to further define breed-associated miRNA signatures in canine OSA. Conclusions: These data reveal significant correlations between breed and miRNA expression in canine OSA, suggesting breed-associated patterns of miRNA dysregulation may play a role in the pathogenesis of OSA.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 184. doi:1538-7445.AM2012-184

Abstract 4825: Common genetic pathways are involved in canine diffuse large B cell lymphoma relapse and human diffuse large B cell lymphoma lympomagenesis

Background/Purpose: The genetic complexity of lymphoma is gradually being unraveled; however, new and better approaches to a molecular understanding are needed. Dogs make an exceptional model for the study of lymphoma because lymphoma occurs spontaneously in this species with a relatively high frequency and it shares many morphological and clinical characteristics with human lymphoma. Very little is known about genetic influences on time to relapse in the most common type of lymphoma in both humans and dogs – diffuse large B-cell lymphoma (DLBCL). Thus, the aim of this study was to determine what genes and pathways are significantly correlated with time to relapse in dogs with spontaneously occurring DLBCL treated with combination chemotherapy.

Methods: Snap frozen lymph node biopsy samples were taken from dogs diagnosed with DLBCL prior to chemotherapy treatment and upon relapse. A total of 31 paired tissue samples were acquired, and a subset of 20 samples were used for this analysis. Affymetrix Canine 2.0 Genechips were used for expression profiling. Spearman's Rank Correlation (SRC) was used to detect genes correlated with clinically relevant quantitative traits. Of available measures, time to relapse provided the most power and was the most relevant to the human condition.

Results: One known pathway altered in human DLBCL involves BCL6. Our analysis found a significant gene expression signature for BCL6 pathways associated with relapsed patients (Fisher's Exact Test, p=0.0005375). Additionally, we reviewed multiple pathways associated with time to relapse and identified a novel unregulated gene- STAP1- that is highly correlated with time to relapse (r = 0.81, p=0.0000018). A protein encoded by this gene functions as a docking protein, acting downstream of Tec tyrosine kinase in B-cell antigen receptor signaling and has not been previously associated with lymphoma. NSMAF, part of the ceramide lipid signaling pathway, was also significantly correlated with patient time to relapse (r=0.76, p=.000014). NSMAF is required for TNF-mediated activation of neutral sphingomyelinase and may play a role in regulating TNF-induced cellular responses such as inflammation, proliferation, and apoptosis. Interestingly, STAP1 has been associated with lipid levels in human subjects. While further validation is required to confirm the results, these findings hint at previously unknown signaling interactions.

Conclusion: We identified genes and pathways that were significantly related to patient time to relapse in canine DLBCL. These results suggest that canine DLBCL shares molecular features with human DLBCL, but also exhibits unique interactions of signaling pathways. Taken together, this validates the dog as a model for the study of DLBCL and lends insight into pathways that may lead to the development of novel therapeutic targets.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4825. doi:10.1158/1538-7445.AM2011-4825

Abstract 1143: Deep sequencing of microRNAs in canine diffuse large B-cell lymphoma

Introduction: MicroRNAs (miRNAs) are small non-coding RNAs 18-24 nucleotides in length that regulate gene expression by targeting the 3’ untranslated region of mRNAs. MiRNAs are often dysregulated in cancer, suggesting they play a role in tumorigenesis. Canine diffuse large B-cell lymphoma (DLBCL) represents one of the most common spontaneously occurring canine cancers. The clinical presentation, histology and biology of canine DLBCL closely parallels the human counterpart of this disease. We hypothesize that canine DLBCL possess a unique miRNA expression signature and that differential microRNA expression contributes to chemoresistance and prognosis. In this study, we sought to determine which miRNAs are differentially expressed in chemotherapy-naïve and relapsed DLBCL and are associated with overall survival.

Methods: Total RNA was isolated by the Trizol method from 48 primary DLBCL lymph node biopsies. 24 of these biopsies represented paired chemotherapy-naïve and relapsed DBCL lymph node biopsies from 12 individual dogs. Clinical follow-up data for dogs treated with CHOP-based protocols was available for 24 dogs. Fragmented libraries were prepared for sequencing from RNA from DLBCL lymph node biopsies. Small RNA sequencing was performed using the Applied Biosystems SOLiD 4 Sequencing system. Data alignment, parsing, and normalization were performed using miRBase V16. Genomic coordinates of miRNAs and isomiRNAs were based on C. familiaris CanFam2.0.

Results: 41 of 48 samples passed quality control criteria for statistical analysis. Small RNA sequencing of canine DLBCL lymph nodes identified many non-canonical isomiRNAs. In some cases, isomiRNAs were expressed at higher levels than the canonical miRNA according to miRBase. The expression of specific miRNAs was significantly different in paired chemotherapy-naive and relapsed canine DLBCL lymph node biopsies. MiR-21, a miRNA with known importance in human tumorigenesis, was significantly overexpressed in relapsed DLBCL as compared to chemotherapy-naïve DLBCL (p<0.001). Overexpression of cfa-miR-204 in canine DLBCL was predictive of poor overall survival (p<0.008).

Conclusion: Our findings suggest that overexpression of cfa-miR-21, contributes to tumor progression in chemotherapy resistant canine DLBCL. Small RNA sequencing revealed that overexpression of cfa-miR-204 in canine DLBCL negatively affects survival. Characterization of miRNA expression in canine DLBCL will facilitate our understanding the biology of this disease and has the potential to identify diagnostic/prognostic factors and targets for therapeutic intervention. Given the clinical and molecular similarities of human and dog lymphoma, this study highlights several miRNA alterations associated with canine lymphoma and suggests that prognostic indicators in dogs may lead to a greater understanding of the genetic events involved in DLBCL initiation and progression in both species.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1143. doi:10.1158/1538-7445.AM2011-1143

Abstract 3011: MicroRNA expression profiles in benign and aggressive canine mast cell tumors

Introduction: MicroRNAs (miRNAs) are small non-coding RNAs (ncRNAs) 18-24 nucleotides in length that regulate gene expression primarily by targeting mRNAs according to the degree of complementarity with their 3’ untranslated region (UTR). MiRNAs are often dysregulated in cancer, suggesting they play a role in tumorigenesis. Canine mast cell tumors (MCT) are a common cutaneous tumor of dogs whose biological behavior varies from relatively benign disease that is cured with surgical excision to aggressive, locally invasive, highly metastatic disease that is poorly responsive even to multimodality therapy. We hypothesize that high grade MCTs possess a unique miRNA expression signature distinct from that found in benign MCTs and that this contributes to their aggressive behavior. In this study, we sought to determine which miRNAs are differentially expressed in benign and aggressive canine MCT.

Methods: Total RNA was isolated by the Trizol (Invitrogen) method from 12 biologically low grade (surgical cure) and 12 biologically high grade (patient died from MCT disease). Mature miRNA expression analysis of preamplified cDNA was done using TaqMan Low Density Arrays (TLDAs), interrogating the expression profile of 378 miRNAs, 151 of whose mature sequences are 100% conserved between human and dog (Sanger miRBase release 12). Normalization was performed with the small nuclear RNA U6 and microRNA expression was calculated utilizing the comparative Ct method. Statistical analysis was performed with RealTime Statminer software (Integromics). P-values of <0.05 were considered statistically significant.

Results: The expression of specific miRNAs was significantly different in biologically low grade and high grade MCTs. 51 miRNAs were differentially expressed in high grade versus low grade tumors (p<0.05). MiRNAs with known importance in human tumorigenesis, including several members of the miR 17-92 cluster (hsa-miR-17, −18a, −18b) and its paralog, the miR-106b-25 cluster (hsa-miR-106b, −93, −25) were significantly overexpressed in high grade tumors as compared to low grade tumors.

Conclusion: Our findings indicate that specific miRNAs contribute to the biologically aggressive canine MCT phenotype. Hierarchical clustering revealed distinct miRNA expression signatures in high grade tumors compared to low grade tumors. Characterization of miRNA expression in canine MCTs will facilitate our understanding the biology of this disease and has the potential to identify diagnostic/prognostic factors and targets for therapeutic intervention.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3011.

Structure and function of tuna tail tendons

The caudal tendons in tunas and other scombrid fish link myotomal muscle directly to the caudal fin rays, and thus serve to transfer muscle power to the hydrofoil-like tail during swimming. These robust collagenous tendons have structural and mechanical similarity to tendons found in other vertebrates, notably the leg tendons of terrestrial mammals. Biochemical studies indicate that tuna tendon collagen is composed of the (alpha1)(2),alpha2 heterotrimer that is typical of vertebrate Type I collagen, while tuna skin collagen has the unusual alpha1,alpha2,alpha3 trimer previously described in the skin of some other teleost species. Tuna collagen, like that of other fish, has high solubility due to the presence of an acid-labile intermolecular cross-link. Unlike collagen in mammalian tendons, no differences related to cross-link maturation were detected among tendons in tuna ranging from 0.05 to 72 kg (approx. 0.25-6 years). Tendons excised post-mortem were subjected to load cycling to determine the modulus of elasticity and resilience (mean of 1.3 GPa and 90%, respectively). These material properties compare closely to those of leg tendons from adult mammals that can function as effective biological springs in terrestrial locomotion, but the breaking strength is substantially lower. Peak tendon forces recorded during steady swimming appear to impose strains of much less than 1% of tendon length, and no more than 1.5% during bursts. Thus, the caudal tendons in tunas do not appear to function as elastic storage elements, even at maximal swimming effort.