Simvastatin exhibits antiproliferative effects on spheres derived from canine mammary carcinoma cells

Anticancer Effects of Mitoquinone via Cell Cycle Arrest and Apoptosis in Canine Mammary Gland Tumor Cells

Treating female canine mammary gland tumors is crucial owing to their propensity for rapid progression and metastasis, significantly impacting the overall health and well-being of dogs. Mitoquinone (MitoQ), an antioxidant, has shown promise in inhibiting the migration, invasion, and clonogenicity of human breast cancer cells. Thus, we investigated MitoQ's potential anticancer properties against canine mammary gland tumor cells, CMT-U27 and CF41.Mg. MitoQ markedly suppressed the proliferation and migration of both CMT-U27 and CF41.Mg cells and induced apoptotic cell death in a dose-dependent manner. Furthermore, treatment with MitoQ led to increased levels of pro-apoptotic proteins, including cleaved-caspase3, BAX, and phospho-p53. Cell cycle analysis revealed that MitoQ hindered cell progression in the G1 and S phases in CMT-U27 and CF41.Mg cells. These findings were supported using western blot analysis, demonstrating elevated levels of cleaved caspase-3, a hallmark of apoptosis, and decreased expression of cyclin-dependent kinase (CDK) 2 and cyclin D4, pivotal regulators of the cell cycle. In conclusion, MitoQ exhibits in vitro antitumor effects by inducing apoptosis and arresting the cell cycle in canine mammary gland tumors, suggesting its potential as a preventive or therapeutic agent against canine mammary cancer.

Effect of Melatonin on Chemoresistance Exhibited by Spheres Derived from Canine Mammary Carcinoma Cells

Mammary cancer is a frequent disease in female dogs, where a high proportion of cases correspond to malignant tumors that may exhibit drug resistance. Within the mammary tumor microenvironment, there is a cell subpopulation called cancer stem cells (CSCs), which are capable of forming spheres in vitro and resisting anti-tumor treatments, partly explaining the recurrence of some tumors. Previously, it has been described that spheres derived from canine mammary carcinoma cells CF41.Mg and REM 134 exhibit stemness characteristics. Melatonin has shown anti-tumor effects on mammary tumor cells; however, its effects have been poorly evaluated in canine mammary CSCs. This study aimed to analyze the effect of melatonin on the chemoresistance exhibited by stem-like neoplastic cells derived from canine mammary carcinoma to cytotoxic drugs such as doxorubicin and mitoxantrone. CF41.Mg and REM 134 cells were cultured in high-glucose DMEM supplemented with fetal bovine serum and L-glutamine. The spheres were cultured in ultra-low attachment plates in DMEM/F12 medium without fetal bovine serum and with different growth factors. The CD44+/CD24-/low phenotype was analyzed by flow cytometry. The viability of sphere-derived cells (MTS reduction) was studied in the presence of melatonin (0.1 or 1 mM), doxorubicin, mitoxantrone, and luzindole. In addition, the gene (RT-qPCR) of the multidrug resistance bombs MDR1 and ABCG2 were analyzed in the presence of melatonin. Both cell types expressed the MT1 gene, which encodes the melatonin receptor MT1. Melatonin 1 mM does not modify the CD44+/CD24-/low phenotype; however, the hormone reduced viability (p < 0.0001) only in CF41.Mg spheres, without inducing an additive effect when co-incubated with cytotoxic drugs. These effects were independent of the binding of the hormone to its receptor MT1, since, by pharmacologically inhibiting them, the effect of melatonin was not blocked. In CF41.Mg spheres, the relative gene expression of ABCG2 and MDR1 was decreased in response to the hormone (p < 0.001). These results indicate that melatonin negatively modulates the cell survival of spheres derived from CF41.Mg cells, in a way that is independent of its MT1 receptor. These effects did not counteract the resistance to doxorubicin and mitoxantrone, even though the hormone negatively regulates the gene expression of MDR1 and ABCG2.

Blockade of isoprenoids biosynthesis by simvastatin induces autophagy-mediated cell death via downstream c-Jun N-terminal kinase activation and cell cycle dysregulation in canine T-cell lymphoma cells

Statins are inhibitors of the mevalonic acid pathway that mediates cellular metabolism by producing cholesterol and isoprenoids and are widely used in treating hypercholesterolaemia in humans. Lipophilic statins, including simvastatin, induce death in various tumour cells. However, the cytotoxic mechanisms of statins in tumour cells remain largely unexplored. This study aimed to elucidate the cytotoxic mechanisms of simvastatin in canine lymphoma cells. Simvastatin induced cell death via c-Jun N-terminal kinase (JNK) activation and autophagy in canine T-cell lymphoma cell lines Ema and UL-1, but not in B-cell lines. Cell death was mediated by induction of caspase-dependent apoptosis in UL-1 cells, but not in Ema cells. Blockade of autophagy by lysosomal inhibitors attenuated simvastatin-induced JNK activation and cell death. Isoprenoids, including farnesyl pyrophosphate and geranylgeranyl pyrophosphate, attenuated simvastatin-induced autophagy, JNK activation, and cell death. In UL-1 cells, simvastatin treatment resulted in the cell cycle arrest at the G2/M phase, which was altered to G0/1 phase cell cycle arrest by treatment with lysosomal inhibitors. These findings demonstrate that depletion of isoprenoids by simvastatin induces autophagy-mediated cell death via downstream JNK activation and cell cycle dysregulation in canine T-cell lymphoma cells.

The effects of statin therapy on brain tumors, particularly glioma: a review

Brain tumors account for less than 2% of all malignancies. However, they are associated with the highest morbidity and mortality rates among all solid tumors. The most common malignant primary brain tumors are glioma or glioblastoma (GBM), which have a median survival time of about 14 months, often suffer from recurrence after a few months following treatment, and pose a therapeutic challenge. Despite recent therapeutic advances, the prognosis for glioma patients is poor when treated with modern therapies, including chemotherapy, surgery, radiation, or a combination of these. Therefore, discovering a new target to treat brain tumors, particularly glioma, might be advantageous in raising progression-free survival and overall survival (OS) rates. Statins, also known as competitive HMG-CoA reductase inhibitors, are effective medications for reducing cholesterol and cardiovascular risk. The use of statins prior to and during other cancer treatments appears to enhance patient outcomes according to preclinical studies. After surgical resection followed by concurrent radiation and treatment, OS for patients with GBM is only about a year. Statins have recently emerged as potential adjuvant medications for treating GBM due to their ability to inhibit cell growth, survival, migration, metastasis, inflammation, angiogenesis, and increase apoptosis in-vitro and in-vivo studies. Whether statins enhance clinical outcomes, such as patient survival in GBM, is still debatable. This study aimed to explore the effects of statin therapy in the context of cancer treatment, with a particular focus on GBM.

New molecular targets in canine hemangiosarcoma-Comparative review and future of the precision medicine

Human angiosarcoma and canine hemangiosarcoma reveal similarities not only in their aggressive clinical behaviour, but especially in molecular landscape and genetic alterations involved in tumorigenesis and metastasis formation. Currently, no satisfying treatment that allows for achieving long overall survival or even prolonged time to progression does not exist. Due to the progress that has been made in targeted therapies and precision medicine the basis for a new treatment design is to uncover mutations and their functions as possible targets to provide tailored drugs for individual cases. Whole exome or genome sequencing studies and immunohistochemistry brought in the last few years important discoveries and identified the most common mutations with probably crucial role in this tumour development. Also, despite a lack of mutation in some of the culprit genes, the cancerogenesis cause may be buried in main cellular pathways connected with proteins encoded by those genes and involving, for example, pathological angiogenesis. The aim of this review is to highlight the most promising molecular targets for precision oncology treatment from the veterinary perspective aided by the principles of comparative science. Some of the drugs are only undergoing laboratory in vitro studies and others entered the clinic in the management of other cancer types in humans, but those used in dogs with promising responses have been mentioned as priorities.

Simvastatin inhibits hepatic stellate cells activation by regulating the ferroptosis signaling pathway

BACKGROUND & AIMS

Ferroptosis is a form of regulated cell death and its promotion in hepatic stellate cells (HSCs) attenuates liver fibrosis. Statins, which are 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, may induce ferroptosis via the downregulation of glutathione peroxidase 4 (GPX4) by inhibiting the mevalonate pathway. However, little evidence is available regarding the association between statins and ferroptosis. Therefore, we investigated the association between statins and ferroptosis in HSCs.

METHODS

Two human HSC cell lines, LX-2 and TWNT-1, were treated with simvastatin, an HMG-CoA reductase inhibitor. Mevalonic acid (MVA), farnesyl pyrophosphate (FPP), and geranylgeranyl pyrophosphate (GGPP) were used to determine the involvement of the mevalonate pathway. We performed a detailed analysis of the ferroptosis signaling pathway. We also investigated human liver tissue samples from patients with nonalcoholic steatohepatitis to clarify the effect of statins on GPX4 expression.

RESULTS

Simvastatin reduced cell mortality and inhibited HSCs activation, accompanied by iron accumulation, oxidative stress, lipid peroxidation, and reduced GPX4 protein expression. These results indicate that simvastatin inhibits HSCs activation by promoting ferroptosis. Furthermore, treatment with MVA, FPP, or GGPP attenuated simvastatin-induced ferroptosis. These results suggest that simvastatin promotes ferroptosis in HSCs by inhibiting the mevalonate pathway. In human liver tissue samples, statins downregulated the expression of GPX4 in HSCs without affecting hepatocytes.

CONCLUSIONS

Simvastatin inhibits the activation of HSCs by regulating the ferroptosis signaling pathway.

Atorvastatin preferentially inhibits the growth of high ZEB-expressing canine cancer cells

The epithelial-to-mesenchymal transition (EMT) is fundamental in cancer progression and contributes to the acquisition of malignant properties. The statin class of cholesterol-lowering drugs exhibits pleiotropic anticancer effects in vitro and in vivo, and many epidemiologic studies have reported a correlation between statin use and reduced cancer mortality. We have shown previously that sensitivity to the anti-proliferative effect of statins varies among human cancer cells and statins are more effective against mesenchymal-like cells than epithelial-like ones in human cancers. There have only been few reports on the application of statins to cancer therapy in veterinary medicine, and differences in statin sensitivity among canine cancer cells have not been examined. In this study, we aimed to clarify the correlation between sensitivity to atorvastatin and epithelial/mesenchymal states in 11 canine cancer cell lines derived from mammary gland, squamous cell carcinoma, lung, and melanoma. Sensitivity to atorvastatin varied among canine cancer cells, with IC₅₀ values ranging from 5.92 to 71.5 μM at 48 h, which were higher than the plasma concentrations clinically achieved with statin therapy. Atorvastatin preferentially attenuated the proliferation of mesenchymal-like cells. In particular, highly statin-sensitive cells were characterized by aberrant expression of the ZEB family of EMT-inducing transcription factors. However, ZEB2 silencing in highly sensitive cells did not induce resistance to atorvastatin. Taken together, these results suggest that high expression of ZEB is a characteristic of highly statin-sensitive cells and could be a molecular marker for predicting whether cancers are sensitive to statins, though ZEB itself does not confer statin sensitivity.

From Conventional to Precision Therapy in Canine Mammary Cancer: A Comprehensive Review

Canine mammary tumors (CMTs) are the most common neoplasm in intact female dogs. Canine mammary cancer (CMC) represents 50% of CMTs, and besides surgery, which is the elective treatment, additional targeted and non-targeted therapies could offer benefits in terms of survival to these patients. Also, CMC is considered a good spontaneous intermediate animal model for the research of human breast cancer (HBC), and therefore, the study of new treatments for CMC is a promising field in comparative oncology. Dogs with CMC have a comparable disease, an intact immune system, and a much shorter life span, which allows the achievement of results in a relatively short time. Besides conventional chemotherapy, innovative therapies have a large niche of opportunities. In this article, a comprehensive review of the current research in adjuvant therapies for CMC is conducted to gather available information and evaluate the perspectives. Firstly, updates are provided on the clinical-pathological approach and the use of conventional therapies, to delve later into precision therapies against therapeutic targets such as hormone receptors, tyrosine kinase receptors, p53 tumor suppressor gene, cyclooxygenases, the signaling pathways involved in epithelial-mesenchymal transition, and immunotherapy in different approaches. A comparison of the different investigations on targeted therapies in HBC is also carried out. In the last years, the increasing number of basic research studies of new promising therapeutic agents on CMC cell lines and CMC mouse xenografts is outstanding. As the main conclusion of this review, the lack of effort to bring the in vitro studies into the field of applied clinical research emerges. There is a great need for well-planned large prospective randomized clinical trials in dogs with CMC to obtain valid results for both species, humans and dogs, on the use of new therapies. Following the One Health concept, human and veterinary oncology will have to join forces to take advantage of both the economic and technological resources that are invested in HBC research, together with the innumerable advantages of dogs with CMC as a spontaneous animal model.

Pharmacokinetic analysis of two different doses of simvastatin following oral administration in dogs

Simvastatin, used orally to treat hyperlipidemia, exhibits highly variable pharmacokinetics (PKs) in humans. The aim of this study was to investigate simvastatin PKs using noncompartmental analysis and population PK models following a single oral administration of two doses (20 and 80 mg) in dogs. Forty beagle dogs were randomly divided into two groups corresponding to the two doses. Blood samples were collected from each group according to the assigned schedule after oral administration. The plasma concentration of simvastatin was determined using liquid chromatography-tandem mass spectrometry. The area under the curve and maximum concentration of simvastatin increased in a dose-dependent manner with high variability. A two-compartment model with first-order absorption (K_a  = 1.83 hr^-1 ) and first-order elimination (clearance [CL/F] = 292 L/h; volume of distribution in the central compartment [V_c /F] = 1506 L) well described the PKs of simvastatin in dogs. Large variability in the PKs of simvastatin was quantitated via modeling approaches, allowing the differentiation of between-subject variability (144.8 CV% for K_a ; 94.7 CV% for CL/F; 97.5 CV% for V_c /F) and residual variability (62.7%). These findings will help facilitate the development of an optimal dose regimen of simvastatin in canines with hypercholesterolemia and may be useful in developing novel formulations.

Understanding of tumourigenesis in canine mammary tumours based on cancer stem cell research

Mammary tumours occur frequently in female dogs, where such tumours exhibit complexity when examined histologically. These tumours are composed not only of proliferative luminal epithelial cells, but also of myoepithelial cells and/or mesenchymal cells with cartilage and osseous tissues in a solitary mass. The origin of this complexed histogenesis remains speculative, but cancer stem cells (CSCs) are likely involved. CSCs possess self-renewing capacity, differentiation potential, high tumourigenicity in immunodeficient mice, and resistance to chemotherapy and radiation. These cells are at the apex of a hierarchy in cancer tissues and are involved in tumour initiation, recurrence, and metastasis. For these reasons, understanding the properties of CSCs is of paramount importance. Analysis of the characteristics of CSCs may contribute to the elucidation of the histogenesis underlying canine mammary tumours, formulation of novel CSC-targeted therapeutic strategies, and development of biomarkers for early diagnostic and prognostic applications. Here, we review research on CSCs in canine mammary tumours, focusing on: (1) identification and properties of CSCs; (2) hypotheses regarding hierarchal structures in simple type, complex type and mixed tumours of the canine mammary gland; and (3) current and prospective studies of CSC metabolism.

Effect of simvastatin on cell proliferation and Ras activation in canine tumour cells

Statins are inhibitors of the mevalonate cascade that is responsible for cholesterol biosynthesis and the formation of intermediate metabolites, farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP) used in the prenylation of proteins. Although statins are widely used in the treatment of hypercholesterolemia, recent studies suggest that they also inhibit proliferation of tumour cells by reducing prenylation of small GTP-binding proteins, such as, Ras. This study aimed to evaluate the effect of simvastatin on cell proliferation and Ras activation in various canine tumour cell lines, including hemangiosarcoma (HSA), melanoma, and lymphoma cell lines. Simvastatin inhibited cell proliferation of all cell lines tested in a concentration- and time-dependent manner, but the susceptibilities were different amongst the cell lines. Simvastatin induced apoptotic cell death via activation of caspase-3 and cell cycle arrest. The cytotoxic effects of simvastatin were attenuated by GGPP and FPP. Simvastatin decreased the amount of prenylated Ras and GTP-bound Ras in HSA and melanoma cell lines, but not in lymphoma cell lines. These results indicate that simvastatin induces cytotoxic effects through the depletion of GGPP and FPP in a variety of canine tumour cells, whereas multiple mechanisms are involved in the effects. Further study is required to elucidate the underlying mechanisms of simvastatin-induced cytotoxic effects in a variety of canine tumour cells.

Melatonin decreases in vitro viability and migration of spheres derived from CF41.Mg canine mammary carcinoma cells

Background

Mammary cancer is a common disease affecting female dogs, where approximately 50% of the cases are malignant. There is a subpopulation of cancer cells with stem cell-like features within the tumour microenvironment, which can form in vitro spheres, cell structures that grow in anchor-free conditions. This cell population shows resistance to conventional antitumor treatments explaining in part the recurrence of some type of cancers. It has been previously reported that spheres derived from CF41.Mg canine mammary carcinoma cells exhibit several stemness features. Melatonin has shown antitumor effects on cancer mammary cells; nevertheless, its effects have been poorly evaluated on canine mammary cancer stem-like cells. In this regard, it has described that melatonin decreases the expression of OCT-4 in CMT-U2229 mammary cancer cells, a transcription factor that participates in the modulation of self-renewal and drug resistance in cancer stem-like cells. The aim of this study was to compare the effects of melatonin on viability and migration of canine mammary carcinoma CF41.Mg-spheres, and CF41.Mg-parental cells. CF41.Mg cells were grown in DMEM high-glucose medium containing 10% bovine foetal serum. CF41.Mg-spheres were cultured in ultra-low attachment plates with serum-free DMEM/F12 containing several growth factors. Cell viability (MTS reduction) and migration (transwell) assays were conducted in presence of melatonin (0.01, 0.1 or 1 mM).

Results

Melatonin decreased cell viability at 1 mM (P < 0.05), with a significant reduction in spheres compared to parental cells at 24 and 48 h (P < 0.05). Cell migration was inhibited in response to non-cytotoxic concentration of melatonin (0.1 mM) (P < 0.05) in spheres and monolayer of cells, no significant differences were detected between both cell subtypes.

Conclusions

These results indicate that melatonin reduces viability and migration of CF41.Mg cells, where spheres exhibit greater sensitivity to the hormone. Thus, melatonin represents a valuable potential agent against mammary cancer cells, especially cancer stem-like cells.

Lovastatin increases the proliferation and osteoblastic differentiation of human gingiva-derived stem cells in three-dimensional cultures

Lovastatin is a cholesterol-lowering agent that also has effects of cell proliferation and apoptosis. The present study was performed to evaluate the effects of lovastatin on the proliferation and osteogenic differentiation of three-dimensional cell spheroids formed from human gingiva-derived stem cells (GDSCs) using concave microwells. GDSCs were plated on polydimethylsiloxane-based concave micromolds and grown in the presence of lovastatin at concentrations of 0, 2 and 6 µM. The morphology of the cells was viewed under an inverted microscope, and cell viability was determined with Cell Counting kit-8 on days 2, 7 and 14. Alkaline phosphatase activity assays were performed to evaluate the osteogenic differentiation on days 2 and 8. Alizarin red-S staining was also used to assess the mineralization of the stem cell spheroids at day 14. The results confirmed that GDSCs formed spheroids in concave microwells. No significant changes were noted with longer incubation time, and no significant differences in cell viability were noted between the three lovastatin groups at each time point. Higher osteogenic differentiation was observed in the 2 µM group when compared with the control. Mineralized extracellular deposits were visible after Alizarin red-S staining, and higher mineralization was noted in the 2 and 6 µM lovastatin groups when compared with the 0 µM control. The relative mineralization values of the 0, 2 and 6 µM groups on day 14 were 39.0±9.6, 69.3±6.0 and 60.9±7.5, respectively. This study demonstrated that the application of lovastatin enhanced the osteogenic differentiation of cell spheroids formed from GDSCs. This suggests that combinations of lovastatin and stem cell spheroids may have the potential for use in tissue engineering.

Therapeutic targeting of lipid synthesis metabolism for selective elimination of cancer stem cells

Cancer stem cells (CSCs) are believed to have an essential role in tumor resistance and metastasis; however, no therapeutic strategy for the selective elimination of CSCs has been established. Recently, several studies have shown that the metabolic regulation for ATP synthesis and biological building block generation in CSCs are different from that in bulk cancer cells and rather similar to that in normal tissue stem cells. To take advantage of this difference for CSC elimination therapy, many studies have tested the effect of blocking these metabolism. Two specific processes for lipid biosynthesis, i.e., fatty acid unsaturation and cholesterol biosynthesis, have been shown to be very effective and selective for CSC targets. In this review, lipid metabolism specific to CSCs are summarized. In addition, how monounsaturated fatty acid and cholesterol synthesis may contribute to CSC maintenance are discussed. Specifically, the molecular mechanism required for lipid synthesis and essential for stem cell biology is highlighted. The limit and preview of the lipid metabolism targeting for CSCs are also discussed.

Effects of statins on the chemoresistance-The antagonistic drug-drug interactions versus the anti-cancer effects

There has been growing interest in the potential anti-cancer activity of statins based on evidence of their anti-proliferative, pro-apoptotic, and radiosensitizing properties, but no studies have focused on the effects of statins on the chemoresistance. In spite of their direct cytostatic/cytotoxic effects on the cancer cells, statins via drug interactions may affect therapeutic effects of the chemotherapy agents and so cause chemoresistance in cancer cells. Here, we aim to present the molecular mechanisms underlying cytotoxic effects of statins on the cancer cells against those mechanisms by which statins may lead to chemoresistance, in order to clarify whether the positive effects of the co-treatment of statins on the efficiency of chemotherapeutic agents is due to the natural anti-cancer effects of statins or it is due to increasing the cellular concentrations of chemotherapy drugs in cancer cells.

CD24 Expression and differential resistance to chemotherapy in triple-negative breast cancer

Breast cancer (BC) is a leading cause of cancer-related death in women. Adjuvant systemic chemotherapies are effective in reducing risks of recurrence and have contributed to reduced BC mortality. Although targeted adjuvant treatments determined by biomarkers for endocrine and HER2-directed therapies are largely successful, predicting clinical benefit from chemotherapy is more challenging. Drug resistance is a major reason for treatment failures. Efforts are ongoing to find biomarkers to select patients most likely to benefit from chemotherapy. Importantly, cell surface biomarkers CD44+/CD24- are linked to drug resistance in some reports, yet underlying mechanisms are largely unknown. This study focused on the potential role of CD24 expression in resistance to either docetaxel or doxorubicin in part by the use of triple-negative BC (TNBC) tissue microarrays. In vitro assays were also done to assess changes in CD24 expression and differential drug susceptibility after chemotherapy. Further, mouse tumor xenograft studies were done to confirm in vitro findings. Overall, the results show that patients with CD24-positive TNBC had significantly worse overall survival and disease-free survival after taxane-based treatment. Also, in vitro cell studies show that CD44+/CD24+/high cells are more resistant to docetaxel, while CD44+/CD24-/low cells are resistant to doxorubicin. Both in vitro and in vivo studies show that cells with CD24-knockdown are more sensitive to docetaxel, while CD24-overexpressing cells are more sensitive to doxorubicin. Further, mechanistic studies indicate that Bcl-2 and TGF-βR1 signaling via ATM-NDRG2 pathways regulate CD24. Hence, CD24 may be a biomarker to select chemotherapeutics and a target to overcome TNBC drug resistance.

Salinomycin inhibits canine mammary carcinoma in vitro by targeting cancer stem cells

Salinomycin (SAL), a polyether ionophore antibiotic, has been demonstrated to selectively kill cancer stem cells (CSCs) in various types of human tumor. The aim of the present study was to investigate the effects of SAL on canine mammary CSCs. CSCs in canine mammary carcinoma cell lines (CMT7364 and CIPp) were identified using a sphere formation assay and flow cytometry. The chemoresistance, invasive potential and expression of stem cell-associated proteins of these spheres was then analyzed. This demonstrated that the spheres exhibited characteristics of CSCs, including a cluster of differentiation (CD)44⁺/CD24^-/low phenotype, upregulation of Wnt/β-catenin signaling pathway-associated proteins and chemoresistance. The viability of the spheres was decreased in a concentration- and time-dependent manner following treatment with SAL, and the spheres did not exhibit increased resistance to SAL compared with their parental cells. In addition, exposure to SAL inhibited sphere-formation and invasive potential in canine mammary CSCs in a dose-dependent manner. Furthermore, SAL decreased the CD44⁺/CD24^-/low population and downregulated the expression of Wnt/β-catenin signaling-associated proteins (β-catenin, Cyclin D1 and octamer-binding transcription factor 4) in the spheres. In conclusion, the present study demonstrated that SAL is an effective inhibitor of canine mammary CSCs in vitro, indicating that SAL is a promising chemotherapeutic agent for the treatment of canine mammary carcinoma.

Identification and characterization of cancer stem cells in canine mammary tumors

Cancer stem cells (CSC) represent a small subpopulation of cells in malignant tumors that possess the unique ability to self-renew, differentiate and resist chemo- and radiotherapy. These cells have been postulated to be the basis for some of the difficulties in treating cancer, and therefore, numerous approaches have been developed to specifically target and eliminate CSC in diverse types of cancer, including breast cancer. Spontaneously occurring mammary tumors in canines share clinical and molecular similarities with the human counterpart, making the dog a potentially powerful model for the study of human breast cancer and clinical trials. Studies focused on canine mammary CSC might therefore enhance our understanding of the biology and possible treatment of the disease in both dogs and humans. In this review, we discuss various approaches currently in use to isolate and characterize canine mammary CSC.

Effect of Melatonin in Epithelial Mesenchymal Transition Markers and Invasive Properties of Breast Cancer Stem Cells of Canine and Human Cell Lines

Cancer stem cells (CSCs) have been associated with metastasis and therapeutic resistance and can be generated via epithelial mesenchymal transition (EMT). Some studies suggest that the hormone melatonin acts in CSCs and may participate in the inhibition of the EMT. The objectives of this study were to evaluate the formation of mammospheres from the canine and human breast cancer cell lines, CMT-U229 and MCF-7, and the effects of melatonin treatment on the modulation of stem cell and EMT molecular markers: OCT4, E-cadherin, N-cadherin and vimentin, as well as on cell viability and invasiveness of the cells from mammospheres. The CMT-U229 and MCF-7 cell lines were subjected to three-dimensional culture in special medium for stem cells. The phenotype of mammospheres was first evaluated by flow cytometry (CD44⁺/CD24^low/- marking). Cell viability was measured by MTT colorimetric assay and the expression of the proteins OCT4, E-cadherin, N-cadherin and vimentin was evaluated by immunofluorescence and quantified by optical densitometry. The analysis of cell migration and invasion was performed in Boyden Chamber. Flow cytometry proved the stem cell phenotype with CD44⁺/CD24^low/- positive marking for both cell lines. Cell viability of CMT-U229 and MCF-7 cells was reduced after treatment with 1mM melatonin for 24 h (P<0.05). Immunofluorescence staining showed increased E-cadherin expression (P<0.05) and decreased expression of OCT4, N-cadherin and vimentin (P<0.05) in both cell lines after treatment with 1 mM melatonin for 24 hours. Moreover, treatment with melatonin was able to reduce cell migration and invasion in both cell lines when compared to control group (P<0.05). Our results demonstrate that melatonin shows an inhibitory role in the viability and invasiveness of breast cancer mammospheres as well as in modulating the expression of proteins related to EMT in breast CSCs, suggesting its potential anti-metastatic role in canine and human breast cancer cell lines.

Cardiovascular Risk and Level of Statin Use Among Women With Breast Cancer in a Cardio-Oncology Clinic

BACKGROUND

Because of the improvements in survival rates, patients with breast cancer are now more likely to die from cardiovascular disease than from cancer. Thus, providing appropriate preventive cardiovascular care to patients with cancer is of the utmost importance.

METHODS

We retrospectively compared the cardiovascular risk and management of 146 women treated at the Cardio-Oncology (Cardio-Onc) and the Obstetrics and Gynecology (Ob-Gyn) clinics. We calculated cardiovascular risk using the American College of Cardiology (ACC)/American Heart Association (AHA) atherosclerotic cardiovascular disease (ASCVD) risk calculator and the Framingham Risk Score Calculator. We also determined the prevalence of appropriate statin use according to both the 2013 ACC/AHA and the 2002 Adult Treatment Panel (ATP) III lipid guidelines.

RESULTS

The 10-year ASCVD risk score was not significantly different between the 2 cohorts. More patients in the Ob-Gyn cohort with an ASCVD risk score >7.5% were already appropriately on statins compared to patients in the Cardio-Onc cohort (60.9% vs 31.0%, respectively, P=0.003), but after the first Cardio-Onc visit, 4 additional patients with breast cancer were prescribed statins (44.8% total). Fourteen (19.2%) Cardio-Onc patients had a high Framingham Risk Score compared to 6 (8.2%) Ob-Gyn patients.

CONCLUSION

We demonstrated that the ASCVD risk is similar between women with breast cancer attending the Cardio-Onc clinic and the women without breast cancer attending the Ob-Gyn clinic, but the Cardio-Onc cohort had significantly more patients with a high Framingham Risk Score. Both clinics had similarly poor rates of appropriate statin prescribing rates according to the ATP III guidelines.