17-AAG and Apoptosis, Autophagy, and Mitophagy in Canine Osteosarcoma Cell Lines

Advances in sex disparities for cancer immunotherapy: unveiling the dilemma of Yin and Yang

A wide sex disparity has been demonstrated in cancer incidence, tumor aggressiveness, prognosis, and treatment response of different types of cancer. The sex specificity of cancer appears to be a relevant issue in managing the disease, and studies investigating the role of sex and gender are becoming extremely urgent. Immunotherapy plays a leading role in cancer treatment, offering a new perspective on advanced malignancies. Gender has not been considered in standard cancer treatment, suggesting increasing the recognition of sex differences in cancer research and clinical management. This paper provides an overview of sex and gender disparities in cancer immunotherapy efficacy, anti-cancer immune response, predictive biomarkers, and so on. We focus on the molecular differences between male and female patients across a broad range of cancer types to arouse the attention and practice of clinicians and researchers in a sex perspective of new cancer treatment strategies.

Sex differences exist in the prevalence, tumor invasiveness, treatment responses, and clinical outcomes of pan-cancer, suggesting that, while not yet incorporated, sex will probably be considered in future practice guidelines.

Inherent genetic differences, overlapping epigenetic alterations, and sex hormone influences underpin everything. Androgen receptors influence the sexual differences in TME by regulating epigenetic and transcriptional differentiation programs. It highlights a sex-based therapeutic target for cancer immunotherapy.

Proper consideration of sex, age, sex hormones/menopause status, and socio-cultural gender differences in clinical investigation and gene association studies of cancer are needed to fill current gaps and implement precision medicine for patients with cancer.

Inhibition of Hsp90 during in vitro maturation under thermoneutral or heat shock conditions compromises the developmental competence of bovine oocytes

Heat shock protein 90 (Hsp90) is critical for cell homeostasis but its role on bovine oocyte maturation is not well known. We investigated the importance of Hsp90 for competence of bovine oocyte using 17-(allylamino)-17-demethoxygeldanamycin (17AAG), an inhibitor of Hsp90, during in vitro maturation (IVM). Three experiments evaluated the effect of 17AAG on developmental competence of oocytes matured in vitro under thermoneutral (38.5ºC) or heat shock (HS; 41.5ºC) temperatures. The first experiment found that the blastocyst rates were lower (P < 0.05) with 2 µM 17AAG compared with the untreated control (0 µM). The abundance of HSF1 transcripts was higher in oocytes matured with 2 µM than with 0 and 1 µM 17AAG, whereas the abundance of HSP90AA1 and HSPA1A transcripts was lower (P < 0.05) with 1 and 2 µM than with 0 µM. The second experiment found that 2 µM 17AAG for 12 or 24 h during IVM decreased (P < 0.05) the blastocysts rates. In the third experiment, the association of 2 μM 17AAG with HS for 12 h during IVM resulted in lower (P < 0.05) blastocysts rates than 17AAG, HS or untreated control. In conclusion, inhibition of Hsp90 during in vitro maturation compromises further embryo development; the association of Hsp90 inhibition with HS aggravates the deleterious effect of both on oocyte developmental competence.

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

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

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

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

Beclin-1 is a novel predictive biomarker for canine cutaneous and subcutaneous mast cell tumors

Mast cell tumors (MCTs) are the most common skin tumor of the dog, and accurately predicting their clinical behavior is critical in directing patient therapy, as they range from benign lesions to a fatal systemic disease. Grading is useful for prognosis, but it cannot predict the behavior of all MCTs. We hypothesized that biomarker immunolabeling in tumor tissues would correlate with patient morbidity and mortality. A clinically annotated tissue microarray (TMA) of primary, recurrent, and metastatic (to lymph node) canine dermal and subcutaneous MCTs was created. Some dogs whose MCTs were included in the TMA did not receive adjunctive treatment after surgical excision of the MCT, whereas others were treated with one or a combination of chemotherapy, radiation, or oral toceranib. Immunohistochemistry for beclin-1, an autophagy protein, was performed followed by digital image analysis. Beclin-1 immunolabeling was higher in recurrent tumors (mean H-score 110.8) than primary MCTs (mean H-score 73.5), and highest in lymph node metastases (mean H-score 138.5) with a significant difference in means (P < .001). While beclin-1 level was not prognostic, it was strongly predictive for survival after adjunctive treatment; dogs with high beclin-1-expressing tumors showed poorer survival compared to those with low beclin-1-expressing tumors (HR = 5.7, P = .02), especially in Kiupel high-grade tumors (HR = 16.3, P = .01). Beclin-1 immunolabeling was the only significant predictive factor by multivariable analysis (P = .04). These findings may improve our ability to predict the response to adjunctive therapy. Importantly, these data suggest that autophagy inhibitors may be useful in improving response to treatment for dogs with high-grade MCTs.

Identification of the specific microRNAs and competitive endogenous RNA mechanisms in osteoporosis

Objective

Osteoporosis and osteoarthritis are metabolic skeletal disorders. This study aimed to identify specific networks of competitive endogenous RNA (ceRNA) in osteoporosis that differ from those in osteoarthritis.

Methods

The dataset GSE74209 was downloaded from the Gene Expression Omnibus, and differentially expressed microRNAs (DEmiRNAs) in osteoporotic samples and osteoarthritic samples were identified. After predicting target genes and linked long noncoding (lnc)RNAs, ceRNA networks of DEmiRNAs were constructed. The nodes that overlapped between ceRNA networks and the Comparative Toxicogenomics Database were selected as key candidates.

Results

Fifteen DEmiRNAs (including 2 downregulated and 13 upregulated miRNAs) were identified in osteoporotic samples versus osteoarthritic samples; these targeted 161 genes and linked to 60 lncRNAs. The ceRNA network consisted of 6 DEmiRNAs, 63 target genes, and 53 lncRNAs. After searching the Comparative Toxicogenomics Database and mining the literature, 2 lncRNAs (MALAT1 and NEAT1), 2 DEmiRNAs (hsa-miR-32-3p, downregulated; and hsa-miR-22-3p, upregulated) and 6 genes (SP1, PTEN, ESR1, ERBB3, CSF1R, and CDK6) that relate to cell death, growth, and differentiation were identified as key candidates separating osteoporosis from osteoarthritis.

Conclusions

Two miRNA–ceRNA networks (including NEAT1/MALAT1-hsa-miR-32-3p-SP1/FZD6 and NEAT1/MALAT1-hsa-miR-22-3p-PTEN/ESR1/ERBB3/CSF1R/CDK6) might have crucial and specific roles in osteoporosis.

Osteoporosis: Current and Emerging Therapies Targeted to Immunological Checkpoints

Osteoporosis is a skeletal pathology characterized by compromised bone strength leading to increased risk of fracture, mainly the spine and hip fractures. Osteoporosis affects more than 200 million people worldwide and because of the skeletal fractures it causes, represents a major cause of morbidity, disability and mortality in older people. Recently, the new discoveries of osteoimmunology have clarified many of the pathogenetic mechanisms of osteoporosis, helping to identify new immunological targets for its treatment opening the way for new and effective therapies with biological drugs. Currently, there are basically two monoclonal antibodies for osteoporosis therapy: denosumab and romosozumab. Here, we focus on the modern approach to the osteoporosis management and in particular, on current and developing biologic drugs targeted to new immunological checkpoints, in the landscape of osteoimmunology.

IL-33/Vitamin D Crosstalk in Psoriasis-Associated Osteoporosis

Patients with psoriasis (Pso) and, in particular, psoriatic arthritis (PsoA) have an increased risk of developing osteoporosis (OP). It has been shown that OP is among the more common pathologies associated with Pso, mainly due to the well-known osteopenizing conditions coexisting in these patients. Pso and OP share common risk factors, such as vitamin D deficiency and chronic inflammation. Interestingly, the interleukin (IL)-33/ST2 axis, together with vitamin D, is closely related to both Pso and OP. Vitamin D and the IL-33/ST2 signaling pathways are closely involved in bone remodeling, as well as in skin barrier pathophysiology. The production of anti-osteoclastogenic cytokines, e.g., IL-4 and IL-10, is promoted by IL-33 and vitamin D, which are stimulators of both regulatory and Th2 cells. IL-33, together with other Th2 cytokines, shifts osteoclast precursor differentiation towards macrophage and dendritic cells and inhibits receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis by regulating the expression of anti-osteoclastic genes. However, while the vitamin D protective functions in OP and Pso have been definitively ascertained, the overall effect of IL-33 on bone and skin homeostasis, because of its pleiotropic action, is still controversial. Emerging evidence suggests a functional link between vitamin D and the IL-33/ST2 axis, which acts through hormonal influences and immune-mediated effects, as well as cellular and metabolic functions. Based on the actions of vitamin D and IL-33 in Pso and OP, here, we hypothesize the role of their crosstalk in the pathogenesis of both these pathologies.

The Osteoporosis/Microbiota Linkage: The Role of miRNA

Hundreds of trillions of bacteria are present in the human body in a mutually beneficial symbiotic relationship with the host. A stable dynamic equilibrium exists in healthy individuals between the microbiota, host organism, and environment. Imbalances of the intestinal microbiota contribute to the determinism of various diseases. Recent research suggests that the microbiota is also involved in the regulation of the bone metabolism, and its alteration may induce osteoporosis. Due to modern molecular biotechnology, various mechanisms regulating the relationship between bone and microbiota are emerging. Understanding the role of microbiota imbalances in the development of osteoporosis is essential for the development of potential osteoporosis prevention and treatment strategies through microbiota targeting. A relevant complementary mechanism could be also constituted by the permanent relationships occurring between microbiota and microRNAs (miRNAs). miRNAs are a set of small non-coding RNAs able to regulate gene expression. In this review, we recapitulate the physiological and pathological meanings of the microbiota on osteoporosis onset by governing miRNA production. An improved comprehension of the relations between microbiota and miRNAs could furnish novel markers for the identification and monitoring of osteoporosis, and this appears to be an encouraging method for antagomir-guided tactics as therapeutic agents.

Does Physical Exercise Always Improve Bone Quality in Rats?

For decades, the osteogenic effect from different physical activities on bone in rodents remained uncertain. This literature review presents for the first time the effects on five exercise models (treadmill running, wheel running, swimming, resistance training and vibration modes) in three different experimental rat groups (males, females, osteopenic) on bone quality. The bone parameters presented are bone mineral density, micro-architectural and mechanical properties, and osteoblast/osteocyte and osteoclast parameters. This review shows that physical activities have a positive effect (65% of the results) on bone status, but we clearly observed a difference amongst the different protocols. Even if treadmill running is the most used protocol, the resistance training constitutes the first exercise model in term of osteogenic effects (87% of the whole results obtained on this model). The less osteogenic model is the vibration mode procedure (31%). It clearly appears that the gender plays a role on the bone response to swimming and wheel running exercises. Besides, we did not observe negative results in the osteopenic population with impact training, wheel running and vibration activities. Moreover, about osteoblast/osteocyte parameters, we conclude that high impact and resistance exercise (such jumps and tower climbing) seems to increase bone formation more than running or aerobic exercise. Among the different protocols, literature has shown that the treadmill running procedure mainly induces osteogenic effects on the viability of the osteocyte lineage in both males and females or ovariectomized rats; running in voluntary wheels contributes to a negative effect on bone metabolism in older male models; whole-body vertical vibration is not an osteogenic exercise in female and ovariectomized rats; whereas swimming provides controversial results in female models. For osteoclast parameters only, running in a voluntary wheel for old males, the treadmill running program at high intensity in ovariectomized rats, and the swimming program in a specific ovariectomy condition have detrimental consequences.

The dual functions of α-tubulin acetylation in cellular apoptosis and autophage induced by tanespimycin in lung cancer cells

Background

Reversible acetylation of α-tubulin has been implicated in modulating microtuble structures and functions, which may subsequently involve in cellular apoptosis and autophage. But how to trigger apoptosis or autophage at what level of acetylated α-tubulin (Ac-α-tubulin) are not known. This study aims to demonstrate the dual functions and molecular mechanisms of α-tubulin acetylation in cellular apoptosis and autophage induced by tanespimycin in Calu-1 cells simultaneously.

Methods

Calu-1 cells were treated with tanespimycin alone or combined administrations of different agents (including TSA, Docetaxel, Rapamycin, 3-MA and Z-vad) respectively and cell lysates were prepared to detect the given proteins by Western Blot. The cell survival was observed by inverted phase contrast microscope and estimated by SRB assay. HDAC6, TAT1 and Hsp90α/β proteins were knocked down by siRNA technique.

Results

By combination administration of tanespimycin with TSA or Docetaxel, the expression of Ac-α-tubulin and cellular apoptosis were enhanced markedly. While combination of tanespimycin and Rapamycin, α-tubulin acetylation and apoptosis were inhibited, but LC3B-II expression was facilitated substantially. When tanespimycin was combined with autophage inhibitor 3-MA, α-tubulin acetylation elevation was apparently, but LC3B-II was attenuated. Apoptosis inhibitor Z-vad blocked partially Caspases activation induced by tanespimycin, but failed to hinder α-tubulin acetylation elevation. According to results of RNA interference, acetyltransferase TAT1, deacetylase HDAC6 and Hsp90 modulated the expression level of α-tubulin acetylation.

Conclusion

We have elucidated that acetylation of α-tubulin induced by tanespimycin has dual functions in cellular apoptosis and autophage and the level of α-tubulin acetylation reaches a degree Calu-1 cells undergo cell apoptosis rather than autophage, implying that the level of acetylated α-tubulin may determine cell fate for survival or apoptosis.

Sex and Gender Influences on Cancer Immunotherapy Response

The global burden of cancer is growing and a wide disparity in the incidence, malignancy and mortality of different types of cancer between each sex has been demonstrated. The sex specificity of cancer appears to be a relevant issue in the management of the disease, and studies investigating the role of sex and gender are becoming extremely urgent. Sex hormones are presumably the leading actors of sex differences in cancer, especially estrogens. They modulate gene expression, alter molecules and generate disparities in effectiveness and side effects of anticancer therapies. Recently immunotherapy aims to improve anticancer treatment strategies reducing off-target effects of chemotherapy and direct cancer cells killing. It is recognized as a fruitful strategy to treat and possible to cure cancer. Immunotherapeutic agents are used to activate or boost the activation of the immune system to fight cancer cells through physiological mechanisms often evaded in the offensive march of the disease. These therapeutic strategies have allowed new successes, but also have serious adverse effects including non-specific inflammation and autoimmunity. Sex and gender issues are of primary importance in this field, due to their recognized role in inflammation, immunity and cancer, and the clarification and understanding of these aspects is a necessary step to increase the responses and to diminish the adverse effects of immunotherapy. This review describes the available knowledge on the role of sex and gender in cancer immunotherapy, and will offer insights to stimulate the attention and practice of clinicians and researchers in a gender perspective of new cancer treatment strategies.

Osteoporosis in Skin Diseases

Osteoporosis (OP) is defined as a generalized skeletal disease characterized by low bone mass and an alteration of the microarchitecture that lead to an increase in bone fragility and, therefore, an increased risk of fractures. It must be considered today as a true public health problem and the most widespread metabolic bone disease that affects more than 200 million people worldwide. Under physiological conditions, there is a balance between bone formation and bone resorption necessary for skeletal homeostasis. In pathological situations, this balance is altered in favor of osteoclast (OC)-mediated bone resorption. During chronic inflammation, the balance between bone formation and bone resorption may be considerably affected, contributing to a net prevalence of osteoclastogenesis. Skin diseases are the fourth cause of human disease in the world, affecting approximately one third of the world's population with a prevalence in elderly men. Inflammation and the various associated cytokine patterns are the basis of both osteoporosis and most skin pathologies. Moreover, dermatological patients also undergo local or systemic treatments with glucocorticoids and immunosuppressants that could increase the risk of osteoporosis. Therefore, particular attention should be paid to bone health in these patients. The purpose of the present review is to take stock of the knowledge in this still quite unexplored field, despite the frequency of such conditions in clinical practice.

Hyperhomocysteinemia is Associated with Inflammation, Bone Resorption, Vitamin B12 and Folate Deficiency and MTHFR C677T Polymorphism in Postmenopausal Women with Decreased Bone Mineral Density

Osteoporosis is an age-related bone disease, affecting mainly postmenopausal women, characterized by decreased bone mineral density (BMD) and consequent risk of fractures. Homocysteine (Hcy), a sulfur-aminoacid whose serum level is regulated by methylenetrahydrofolate reductase (MTHFR) activity and vitamin B12 and folate as cofactors, is a risk factor for inflammatory diseases. Literature data concerning the link between Hcy and osteoporosis are still debated. The aim of our study was to assess the relationship among Hcy and BMD, inflammation, vitamin status and bone turnover in postmenopausal osteoporosis. In 252 postmenopausal women, BMD was measured by dual-energy X-ray absorptiometry (DXA). In addition to serum Hcy, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and bone turnover markers (bone alkaline phosphatase-BAP, osteocalcin-OC, C-terminal telopeptide of type I collagen (CTX), vitamin deficiencies and MTHFR-C677T polymorphism were evaluated. Hcy, inflammation, bone resorption markers and prevalence of C677T polymorphism were higher, whereas vitamin D, B12, folate, and bone formation markers were lower in women with decreased BMD compared to those with normal BMD. Our results suggest a significant association between Hcy, BMD and inflammation in postmenopausal osteoporosis. The regulation of Hcy overproduction and the modulation of the inflammatory substrate could represent additional therapeutic approaches for osteoporosis prevention.

Neuroendocrine Cancer of the Breast: A Rare Entity

Neuroendocrine breast cancer (NEBC) is a rare histotype of breast carcinoma that presents, in most cases, positive hormone receptors and negative HER2. Indeed, the analysis of gene expression profiles revealed that NEBC belongs mainly to the luminal subtype. Cases of HER2-positive and triple-negative NEBC are rare. The cardinal treatment of early NEBC is surgery, similar to the treatment of invasive non-special histological type carcinoma. The use of radiotherapy follows the criteria applied in infiltrating breast cancer of non-special histotype. In the post-operative phase, therefore after the surgical treatment of mammary quadrantectomy, or mastectomy associated with homolateral sentinel lymph node removal ± axillary dissection, based on the histopathological characteristics of the tumor, the use of chemotherapy (anthracycline + taxane) and/or hormone therapy, whether or not associated with anti-HER2 therapy (trastuzumab) is the rule. Literature data report the use of cisplatin and etoposide, as in small cell lung cancers. Most of the information currently available derive from single case reports or a series of clinical cases; it follows the difficulty of formulating definite recommendations on the correct management of this histological type of breast cancer. This review describes available knowledge on this rare entity to improve the diagnostic and therapeutic strategies and offer insights to stimulate exploration of the many aspects still unknown.

Sex and Gender Aspects for Patient Stratification in Allergy Prevention and Treatment

Allergies are rapidly worsening in recent decades, representing the most common immunological diseases. The mechanism of disorders such as asthma, rhinocongiuntivitis, urticaria, atopic dermatitis, food and drug allergies, and anaphylaxis still remain unclear and consequently treatments is mostly still symptomatic and aspecific while developments of new therapies are limited. A growing amount of data in the literature shows us how the prevalence of allergic diseases is different in both sexes and its changes over the course of life. Genes, hormones, environmental and immunological factors affect sex disparities associated with the development and control of allergic diseases, while they more rarely are considered and reported regarding their differences related to social, psychological, cultural, economic, and employment aspects. This review describes the available knowledge on the role of sex and gender in allergies in an attempt to improve the indispensable gender perspective whose potential is still underestimated while it represents a significant turning point in research and the clinic. It will offer insights to stimulate exploration of the many aspects still unknown in this relationship that could ameliorate the preventive, diagnostic, and therapeutic strategies in allergic diseases.

IL-33/IL-31 Axis in Osteoporosis

The study of the immunoskeletal interface has led to the discovery of numerous cytokines involved in the regulation of bone remodeling, providing valuable information on the pathogenesis of osteoporosis. The role of inflammatory cytokines of the Th1 and Th17 profile in osteoporosis is well known. Here we focus on two newly discovered Th2 cytokines, IL-31 and IL-33, whose implications in osteoporosis are recently emerging. Clinical and experimental observations suggest an important role of the IL-33/IL-31 axis in osteoporosis. IL-33 induces IL-31 secretion by Th2 cells and inhibits RANKL-dependent osteoclastogenesis, thus counteracting bone loss. IL-31 influences Th1/Th17 osteoclastogenetic inflammation and limits Th2 osteoprotective processes, thus favoring osteoporosis. Better knowledge of the role of IL-31 and IL-33 and their receptor complexes in osteoporosis could provide an interesting perspective for the development of new and more effective therapies, possibly with less side effects.

Does Allergy Break Bones? Osteoporosis and Its Connection to Allergy

: Osteoporosis and allergic diseases are important causes of morbidity, and traditionally their coexistence has been attributed to causality, to independent processes, and they were considered unrelated. However, the increasing knowledge in the field of osteoimmunology and an increasing number of epidemiological and biological studies have provided support to a correlation between bone and allergy that share pathways, cells, cytokines and mediators. If the link between allergic pathology and bone alterations appears more subtle, there are conditions such as mastocytosis and hypereosinophilic or hyper-IgE syndromes characterized by the proliferation of cells or hyper-production of molecules that play a key role in allergies, in which this link is at least clinically more evident, and the diseases are accompanied by frank skeletal involvement, offering multiple speculation cues. The pathophysiological connection of allergy and osteoporosis is currently an intriguing area of research. The aim of this review is to summarize and bring together the current knowledge and pursue an opportunity to stimulate further investigation.

mTOR Links Tumor Immunity and Bone Metabolism: What are the Clinical Implications?

Phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) plays a crucial role in the control of cellular growth, proliferation, survival, metabolism, angiogenesis, transcription, and translation. In most human cancers, alterations to this pathway are common and cause activation of other downstream signaling pathways linked with oncogenesis. The mTOR pathway modulates the interactions between the stroma and the tumor, thereby affecting both tumor immunity and angiogenesis. Inflammation is a hallmark of cancer, playing a central role in the tumor dynamics, and immune cells can exert antitumor functions or promote the growth of cancer cells. In this context, mTOR may regulate the activity of macrophages and T cells by regulating the expression of cytokines/chemokines, such as interleukin (IL)-10 and transforming growth factor (TGF-β), and/or membrane receptors, such as cytotoxic T-Lymphocyte protein 4 (CTLA-4) and Programmed Death 1 (PD-1). Furthermore, inhibitors of mammalian target of rapamycin are demonstrated to actively modulate osteoclastogenesis, exert antiapoptotic and pro-differentiative activities in osteoclasts, and reduce the number of lytic bone metastases, increasing bone mass in tumor-bearing mice. With regard to the many actions in which mTOR is involved, the aim of this review is to describe its role in the immune system and bone metabolism in an attempt to identify the best strategy for therapeutic opportunities in the metastatic phase of solid tumors.

Establishment of three-dimensional canine osteosarcoma cell lines showing vasculogenic mimicry and evaluation of biological properties after treatment with 17-AAG

Vasculogenic mimicry (VM) is an alternative type of blood perfusion characterized by formation of non-endothelial cell-lined microcirculatory channels and is responsible for aggressive tumour biology and increased tumour-related mortality. VM-correlated genes are associated with vascular endothelial grown factor receptor 1 (VEGFR1), and hypoxia-related (hypoxia inducible factor 1 α-HIF1α) signalling pathways, whose molecules are client proteins of Hsp90 (heat shock protein 90) and are potential therapeutic targets. This pilot study was aimed to investigate vasculogenic mimicry in a three-dimensional (3D) cell culture system of two aggressive canine osteosarcoma (OSA) cell lines (D22 and D17), and to evaluate the response of these cells to 17-AAG (17-N-allylamino-17-demethoxygeldanamycin) treatment in relation to tubular-like structure formation in vitro. Only D17 cell line formed hollow matrix channels in long-term 3D cultures and assumed endothelial morphology, with cells expressing both Hsp90 and VEGFR1, but lacking expression of endothelial marker CD31. 17-AAG treatment inhibited migration of D17 OSA cells, also decreasing VM markers in vitro and inducing a reduction of HIF1α transcript and protein in this cell line. Taken together, these preliminary data indicate that the biological effects of 17-AAG on D17 3D culture and on HIF1α regulation can provide interesting information to translate these findings from the basic research to clinical approach for the treatment of canine OSA as a model in comparative oncology.

Heat shock protein 90α couples with the MAPK-signaling pathway to determine meiotic maturation of porcine oocytes

Heat shock protein 90 (Hsp90) functions as a molecular chaperone in its interaction with clients to influence multiple cellular and physiological processes. However, our current understanding on Hsp90's relationship with mammalian oocyte maturation is still very limited. Here, we aimed to investigate Hsp90's effect on pig oocyte meiotic maturation. Endogenous Hsp90α was constantly expressed at both mRNA and protein levels in porcine maturing oocytes. Addition of 2 µM 17-allylamino-17-demethoxygeldanamycin (17-AAG), the Hsp90 inhibitor, to in vitro mature cumulus-oocyte complexes (COC) significantly decreased Hsp90α protein level (P < 0.05), delayed germinal vesicle breakdown (GVBD) (P < 0.05), and impeded the first polar body (PB1) extrusion (P < 0.01) of porcine oocytes. 2 µM 17-AAG treatment during in vitro maturation also decreased the subsequent development competence as indicated by the lower cleavage (P < 0.001) and higher fragmentation (P < 0.001) rates of parthenotes, whereas no effects on the percentage and average cell number of blastocysts were found. Immunodepletion of Hsp90α by antibody microinjection into porcine oocytes at germinal vesicle and metaphase II stages induced similar defects of meiotic maturation and parthenote development, to that resulted from 2 µM inhibitor 17-AAG. For oocytes treated by 2 µM 17-AAG, the cytoplasm and membrane actin levels were weakened (P < 0.01), and the spindle assembly was disturbed (P < 0.05), due to decreased p-ERK1/2 level (P < 0.05). However, the mitochondrial function and early apoptosis were not affected, as demonstrated by rhodamine 123 staining and Annexin V assays. Our findings indicate that Hsp90α can couple with mitogen-activated protein kinase to regulate cytoskeletal structure and orchestrate meiotic maturation of porcine oocytes.

The autophagy inhibitor spautin-1, either alone or combined with doxorubicin, decreases cell survival and colony formation in canine appendicular osteosarcoma cells

Dogs diagnosed with appendicular osteosarcoma typically succumb to metastatic disease within a year of diagnosis. The current standard of care for curative intent, amputation followed by adjuvant chemotherapy, increases survival time but chemoresistance is a major contributor to mortality. Unfortunately, the mechanisms driving the progression of metastatic disease and the development of chemoresistance are unknown. One theory is that autophagy may contribute to chemoresistance by providing neoplastic cells with a mechanism to survive chemotherapy treatment. Our objective was to evaluate the effect of combining an autophagy inhibitor with a standard chemotherapeutic drug on response to chemotherapy in canine appendicular osteosarcoma cells. We hypothesized that combining the autophagy inhibitor spautin-1 with doxorubicin treatment would enhance chemoresponsiveness. Using commercial (D17) and primary cell lines derived from 1° and 2° sites of osteosarcoma, we showed that this combination treatment enhances cell killing and inhibits colony formation. Our findings support the theory that autophagy contributes to chemoresistance in canine appendicular osteosarcoma and indicate that adding an autophagy inhibitor to the standard of care has the potential to improve outcome.