1,720,962 research outputs found
The Extracellular Vesicles (EVs) and their role in primary and metastatic bone tumors
Full text linkExtracellular vesicles (EVs) are defined as spherical structures surrounded by a lipid bilayer released by cells into various biological fluids. EVs represent an important means of communication and transport of signal molecules between cells, playing a crucial role as mediators of many physiological and pathological processes, including cancer. In recent years, several studies have been emerging on their involvement in the onset and progression of primary bone tumors and metastases, both addressed in Chapter 1 of this PhD thesis.
In a previous work conducted in our lab, it was shown that there is extensive EV-mediated communication among the cells of the bone tissue. Since the latter is one of the most common sites for breast cancer metastases, we set out to evaluate the EVs-mediated interaction between MDA-MB-231 cells, a human osteotropic breast cancer cell line, and bone resident cells. In particular, we showed that EVs from MDA-MB-231 have a direct role on bone cell physiology, stimulating osteoclastogenesis, angiogenesis, and inhibiting osteoblast differentiation. We also observed that soluble factors, released by MDA-MB-231 cells, educate osteoblasts, increasing the osteoclastogenic potential of the EVs isolated from the latter and thus creating a microenvironment conducive to bone destruction and to tumor growth. These results are reported in more detail in Chapter 2.
Subsequently, we focused on the mechanisms underlying the progression of primary bone tumors, studying the EVs-mediated interaction between the human osteosarcoma cell line MNNG/HOS and the bone cells. We treated osteoblasts with EVs from MNNG/HOS, observing a significant reduction in their number, as well as their metabolic and alkaline phosphatase (Alp) activity. We found a reduction in the expression of genes associated with the cell cycle and osteoblast differentiation. Furthermore, we observed that osteoblasts were induced by tumor EVs to produce and release pro-inflammatory and pro-tumoral factors in the bone microenvironment. In addition to these results, described in Chapter 3, we found that EVs from MNNG/HOS increase the expression of Serpin b2 in osteoblasts, a protein often overexpressed in tumor tissues and still under our investigation. Furthermore, we found that EVs from MNNG/HOS promote angiogenesis, both in vitro and in vivo.
In conclusion, the results obtained during my PhD underline the importance of tumor-derived EVs in the crosstalk between cancer cells and resident cells in the bone microenvironment, and show their role in influencing bone cells behavior, in particular of osteoblasts, and their release of determining factors, hopefully useful in advancing the current research on therapeutic and prognostic potential of EVs in cancer treatment
Liquid biopsies in primary and secondary bone cancers
Full text linkLiquid biopsies are a powerful tool to non-invasively analyze tumor phenotype and progression as well as drug resistance. In the bone oncology field, liquid biopsies would be particularly important to develop, since standard biopsies can be very painful, dangerous (e.g., when found in proximity to the spinal cord), and hard to collect. In this review, we explore the recent advances in liquid biopsies in both primary (osteosarcoma and Ewing sarcoma) and secondary bone cancers (breast, prostate, and lung cancer-induced bone metastases), presenting their current role and highlighting their unexpressed potential, as well as the barriers limiting their possible adoption, including costs, scalability, reproducibility, and isolation methods. We discuss the use of circulating tumor cells, cell-free circulating tumor DNA, and extracellular vesicles for the purpose of improving diagnosis, prognosis, evaluation of therapy resistance, and driving therapy decisions in both primary and secondary bone malignancies
Osteoblast-derived extracellular vesicles influence MNNG/HOS osteosarcoma cells, reducing their migration and affecting their metabolic activity and redox balance
No full textPrimary Bone Tumors and Breast Cancer-Induced Bone Metastases: In Vivo Animal Models and New Alternative Approaches
Full text linkBone is the preferential site of metastasis for the most common tumors, including breast cancer. On the other hand, osteosarcoma is the primary bone cancer that most commonly occurs and causes bone cancer-related deaths in children. Several treatment strategies have been developed so far, with little or no efficacy for patient survival and with the development of side effects. Therefore, there is an urgent need to develop more effective therapies for bone primary tumors and bone metastatic disease. This almost necessarily requires the use of in vivo animal models that better mimic human pathology and at the same time follow the ethical principles for the humane use of animal testing. In this review we aim to illustrate the main and more suitable in vivo strategies employed to model bone metastases and osteosarcoma. We will also take a look at the recent technologies implemented for a partial replacement of animal testing
Effects of osteoblast-derived extracellular vesicles on aggressiveness, redox status and mitochondrial bioenergetics of MNNG/HOS osteosarcoma cells
No full textOsteosarcoma is the most common primary bone malignancy. The crosstalk between osteosarcoma and the surrounding tumour microenvironment (TME) drives key events that lead to metastasization, one of the main obstacles for definitive cure of most malignancies. Extracellular vesicles (EVs), lipid bilayer nanoparticles used by cells for intercellular communication, are emerging as critical biological mediators that permit the interplay between neoplasms and the tumour microenvironment, modulating re-wiring of energy metabolism and redox homeostatic processes. We previously showed that EVs derived from the human osteosarcoma cells influence bone cells, including osteoblasts. We here investigated whether the opposite could also be true, studying how osteoblast-derived EVs (OB-EVs) could alter tumour phenotype, mitochondrial energy metabolism, redox status and oxidative damage in MNNG/HOS osteosarcoma cells.These were treated with EVs obtained from mouse primary osteoblasts, and the following endpoints were investigated: i) cell viability and proliferation; ii) apoptosis; iii) migration and invasive capacity; iv) stemness features; v) mitochondrial function and energy metabolism; vi) redox status, antioxidant capacity and oxidative molecular damage. OB-EVs decreased MNNG/HOS metabolic activity and viability, which however was not accompanied by impaired proliferation nor by increased apoptosis, with respect to control. In addition, OB-EV-treated cells exhibited a significant reduction of motility and in vitro invasion as compared to untreated cells. Although the antioxidant N-acetyl-L-cysteine reverted the cytotoxic effect of OB-EVs, no evidence of oxidative stress was observed in treated cells. However, the redox balance of glutathione was significantly shifted towards a pro-oxidant state, even though the major antioxidant enzymatic protection did not respond to the pro-oxidant challenge. We did not find strong evidence of mitochondrial involvement or major energy metabolic switches induced by OB-EVs, but a trend of reduction in seahorse assay basal respiration was observed, suggesting that OB-EVs could represent a mild metabolic challenge for osteosarcoma cells. In summary, our findings suggest that OB-EVs could serve as important means through which TME and osteosarcoma core cross-communicate. For the first time, we proved that OB-EVs reduced osteosarcoma cells’ aggressiveness and viability through redox-dependent signalling pathways, even though mitochondrial dynamics and energy metabolism did not appear as processes critically needed to respond to OB-EVs
Human osteosarcoma cell secretome impairs neonatal mouse calvarial osteogenic cells functions and modifies the nanoparticles-derived protein profile
Full text linkOsteosarcoma is the most common pediatric primary bone tumor, whose growth strictly relies on a complex interplay among tumor cells, resident cells, and the bone matrix. We investigated the effects of secretome collected from the human osteosarcoma cell line MNNG/HOS on mouse primary osteogenic cells, finding that prolonged exposure alters osteoblast phenotype and activity. MNNG/HOS secretome also reduces the production and release of collagen type I, the most abundant constituent of the bone matrix, and hinders osteoblast ability to form nodule of mineralization, compared to osteogenic cells treated with their own secretome. Given the crucial role exerted by secretome on tumor growth, we aimed also to determine whether osteosarcoma cells secretome can influence the osteoblast release of extracellular nanoparticles (NPs) as well as NPs protein cargo. Intriguingly, we found that MNNG/HOS secretome exerts a direct effect on osteoblast-NPs, reprogramming their protein cargo and subsequently influencing extracellular matrix composition and collagen formation, in favor of tumor progression. Overall, our findings indicate the ability of MNNG/HOS cells to fuel their own malignancy by deranging bone matrix composition and stimulating osteoblast-nanoparticles shuttling of osteosarcoma promoting factors
Pre-proenkephalin 1 is Downregulated Under Unloading and is Involved in Osteoblast Biology
Full text linkPre-proenkephalin 1 (Penk1) is a pro-neuropeptide that belongs to the typical opioid peptide’s family, having analgesic properties. We previously found Penk1 to be the most downregulated gene in a whole gene profiling analysis performed in osteoblasts subjected to microgravity as a model of mechanical unloading. In this work, Penk1 downregulation was confirmed in the bones of two in vivo models of mechanical unloading: tail-suspended and botulinum toxin A (botox)-injected mice. Consistently, in the sera from healthy volunteers subjected to bed rest, we observed an inverse correlation between PENK1 and bed rest duration. These results prompted us to investigate a role for this factor in bone. Penk1 was highly expressed in mouse bone, but its global deletion failed to impact bone metabolism in vivo. Indeed, Penk1 knock out (Penk1−/−) mice did not show an overt bone phenotype compared to the WT littermates. Conversely, in vitro Penk1 gene expression progressively increased during osteoblast differentiation and its transient silencing in mature osteoblasts by siRNAs upregulated the transcription of the Sost1 gene encoding sclerostin, and decreased Wnt3a and Col1a1 mRNAs, suggesting an altered osteoblast activity due to an impairment of the Wnt pathway. In line with this, osteoblasts treated with the Penk1 encoded peptide, Met-enkephalin, showed an increase of Osx and Col1a1 mRNAs and enhanced nodule mineralization. Interestingly, primary osteoblasts isolated from Penk1−/− mice showed lower metabolic activity, ALP activity, and nodule mineralization, as well as a lower number of CFU-F compared to osteoblasts isolated from WT mice, suggesting that, unlike the transient inhibition, the chronic Penk1 deletion affects both osteoblast differentiation and activity. Taken together, these results highlight a role for Penk1 in the regulation of the response of the bone to mechanical unloading, potentially acting on osteoblast differentiation and activity in a cell-autonomous manner
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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