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Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitochondrial abnormalities represent a major cytopathology in Huntington's disease (HD), a fatal neurodegenerative disease caused by CAG repeat expansions in the gene encoding huntingtin (Htt). In the present study, we investigated whether defects in the mitochondrial respiratory function are consequences of the expression of mutant Htt or they promote the formation of Htt aggregates. To take advantage of existing mitochondrial DNA mutants, we developed human osteosarcoma 143B cells expressing mutant Htt in an inducible manner and found that cells expressing mutant Htt but not wild-type Htt exhibited a reduced activity of complex III and an increased activity of complex IV. Conversely, pharmacological treatments that inhibited complex III activity significantly promoted the formation of Htt aggregates. This complex III-mediated modulation of Htt aggregates was also observed in a neuronal progenitor RN33B cell line transduced by lentivirus carrying mutant Htt. This effect of complex III inhibition on the Htt aggregates appeared to be mediated by the inhibition of proteasome activity, but not by ATP depletion or production of reactive oxygen species. Accordingly, complex III mutant cells also showed decreased proteasome activity. These results suggest the presence of a feedback system connecting the mitochondrial respiratory complex III and the production of Htt aggregates. Our results suggest that therapeutic interventions targeting complex III and/or proteasome could ameliorate the progress of HD.
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PMID:Extended polyglutamine repeats trigger a feedback loop involving the mitochondrial complex III, the proteasome and huntingtin aggregates. 1735 14

Chloroacetaldehyde, a metabolite of the anticancer drug ifosfamide, may be responsible for serious adverse effects like encephalopathy in ifosfamide chemotherapy. In this study, we demonstrate that chloroacetaldehyde, but not ifosfamide, induces cell death in human osteosarcoma Saos-2 cells and we investigated the mechanism by which this occurs. Chloroacetaldehyde above 30 micromol/l induced significant cell death in a time-dependent manner. Thiol compounds such as N-acetyl cysteine, glutathione and dithiothreitol protected the cells against chloroacetaldehyde-induced cell death, although other nonthiol compounds and the antioxidative enzymes superoxide dismutase and catalase did not, suggesting that reactive oxygen species might not mediate cell death. In cells exposed to chloroacetaldehyde, levels of both total thiols and glutathione were significantly reduced. Chloroacetaldehyde also collapsed the mitochondrial membrane potential of these cells, induced the release of cytochrome c from mitochondria to the cytosol and significantly reduced cellular ATP levels during the course of death. The mitochondrial potential collapse was also prevented by thiol compounds. Flow cytometric analyses by means of annexin-V and propidium iodide double staining and immunofluorescence staining of active caspase-3 revealed that cells subjected to a lethal dose of chloroacetaldehyde displayed features characteristic of necrosis and that caspase-3 was not activated in response to chloroacetaldehyde. Taken together, these findings suggest that Saos-2 cells exposed to chloroacetaldehyde die by necrosis resulting from a decrease in intracellular thiols, disruption of the mitochondrial membrane potential and the depletion of cellular ATP.
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PMID:Necrotic pathway in human osteosarcoma Saos-2 cell death induced by chloroacetaldehyde. 1741 23

Reactive oxygen species (ROS) have long been considered as toxic by-products of aerobic metabolism and appear involved in the pathogenesis of degenerative diseases. The physiological role of ROS as second messengers in cell signal transduction is, on the other hand, increasingly recognized. Here we investigated the effects of H(2)O(2) and extracellular nucleotides on calcium signalling in four osteoblastic cell lines. In the highly differentiated HOBIT cells, sensitive to nanomolar concentrations of ADP and UTP, millimolar H(2)O(2) induced oscillatory increases of the cytosolic calcium concentration followed by a steady and sustained calcium increase. Long lasting rhythmic calcium activity was induced by micromolar H(2)O(2) doses. The H(2)O(2)-induced calcium signals, due to both release from intracellular stores and influx from the extracellular milieu, were totally prevented by incubating the cells with the P2 receptor antagonist suramin or with the ATP/ADP hydrolyzing enzyme apyrase. In the osteosarcoma SaOS-2 cells micromolar H(2)O(2) failed to evoke calcium signals and millimolar H(2)O(2) induced a slowly developing calcium influx which was unaffected by suramin and apyrase. These cells responded to micromolar concentrations of ATP and ADP, but were largely insensitive to UTP. ROS 17/2.8 osteosarcoma cells were totally insensitive to ATP, ADP and UTP in keeping with the evidence that these cells lack functional purinergic receptors. In these cells, H(2)O(2) up to 1mM did not increase the cytosolic calcium concentration. In ROS/P2Y(2) cells, stably expressing the P2Y(2) receptor, spontaneous calcium oscillations were observed in 38% of the population and nanomolar concentration of extracellular ATP or UTP activated oscillations in quiescent cells. Spontaneous calcium signals were inhibited by suramin and apyrase. In these cells H(2)O(2) induced oscillatory calcium activity that was blocked by suramin and apyrase. The sensitivity of ROS/P2Y(2) cells to UTP decreased significantly in the presence of DTT, which was effective also in inhibiting spontaneous calcium oscillations. On the other hand, the membrane-impermeant thiol oxidant DTNB induced calcium oscillations that were inhibited by incubating the cells with suramin or apyrase. Since peroxide did not increase extracellular ATP in these cell lines, we propose that, in osteoblasts, mild oxidative conditions could activate purinergic signalling through the sensitization of P2Y(2) receptor.
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PMID:H(2)O(2) modulates purinergic-dependent calcium signalling in osteoblast-like cells. 1782 6

The purpose of this study was to investigate the anti-osteosarcoma effects and mechanisms of 4-O-amino-phenol-4'-demethylepipodophyllotoxin ether (ODE), a new derivative of podophyllotoxin. The results showed that ODE inhibited proliferation of K562, OS-9901, CNE, BGC-823 and Tca-8113 cells in a time- and concentration-dependent manner as determined by microculture tetrazolium (MTT) assay. OS-9901 and K562 cells treated with ODE for 24 h showed cell cycle arrest at G(2)/M and a parallel decrease in G(0)/G(1) and S phase as detected by flow cytometry (FCM). Meanwhile, a fraction of cells with hypodiploid DNA content representing apoptosis were detected by FCM. Morphology observation also revealed typical apoptotic features, including shrinkage of cellular and nuclear membranes, condensed heterochromatin around the nuclear periphery and cytoplasmic vacuolation in OS-9901 cells. Under a confocal laser scanning microscope, intracellular Ca2+ and Mg2+ concentrations were greatly increased whereas the pH value, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were markedly reduced in OS-9901 cells after treatment with ODE. Taken together, these results suggest that the anti-osteosarcoma mechanisms of ODE are attributed to apoptosis through increasing intracellular Ca2+ and Mg2+ concentrations, and reducing pH value, MMP and ROS.
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PMID:Anti-osteosarcoma effects and mechanisms of 4-O-amino-phenol-4'-demethylepipodophyllotoxin ether. 1823 65

Cells lacking mitochondrial genome (defined as rho(0)) are useful models in studies on cancer, aging, mitochondrial diseases and apoptosis, but several of their functional aspects have been poorly characterized. Using different clones of rho(0) cells derived from the human osteosarcoma line 143B, we have tested the effects of different apoptogenic molecules such as staurosporine (STS), doxorubicin, daunomycin and quercetin, and have analyzed apoptosis, mitochondrial membrane potential (MMP), levels of oxygen free radicals, reduced glutathione (GSH) content, and expression of P-glycoprotein (P-gp). When compared to parental cells, rho(0) cells resulted much less sensitive to apoptosis. MMP was well maintained in rho(0) cells, and remained unchanged after adding apoptogenic agents, and did not change after treatment with molecules able to depolarize mitochondria such as valinomycin. After adding STS, the production of reactive oxygen species was similar in both cell types, but rho(0) cells maintained higher levels of GSH. In rho(0) cells, P-gp was strongly over-expressed both at mRNA and protein level, and its functionality was higher. The resistance to apoptosis of rho(0) cells could be not only due to an increased scavenger capacity of GSH, but also due to a selection of multidrug resistant cells that hyperexpress P-gp.
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PMID:Resistance of mtDNA-depleted cells to apoptosis. 1830 87

We developed a new radiosensitization treatment using a hydrogen peroxide solution (Oxydol)-soaked gauze named KORTUC I (Kochi Oxydol-Radiation Therapy for Unresectable Carcinomas) for superficially exposed and unresectable neoplasms, such as malignant melanoma and malignant fibrous histiocytoma (MFH), based on our experimental results which demonstrated hydrogen peroxide as a strong radiosensitizer for the highly radioresistant osteosarcoma cell line, HS-Os-1. Five patients entered our clinical trial, one of whom had unresectable malignant melanoma; one, unresectable MFH; one, unresectable extramammary Paget's disease; one, locally advanced breast cancer and one with locally recurrent skin cancer. These patients were treated with radiation therapy using a high-energy electron beam from a linear accelerator. The total dose was 48 Gy, and each fraction size was 4 Gy. Radiation therapy for these patients was performed three times per week. Each time the radiation therapy was carried out, the superficially exposed tumors of these patients were covered with hydrogen peroxide solution (Oxydol)-soaked gauze, and the lesion was gently massaged for several minutes so as to allow the hydrogen peroxide solution to soak deeply into the tumor. In the treatment results, two of these five patients showed a clinically complete response (cCR) two to three months following the end of the KORTUC I radiosensitization treatment. The other three patients showed a clinically partial response (cCR) showing a decrement of more than half of the pretreatment volume. KORTUC I was completed without any severe complications, excluding mild radiation-induced dermatitis/mucositis (Grade I). In conclusion, this newly developed radiosensitization treatment using hydrogen peroxide solution (Oxydol)-soaked gauze for superficially exposed unresectable/radioresistant neoplasms appears to be an effective and valuable method of radiosensitization in terms of the blockade of anti-oxidative enzymes such as peroxidases, resulting in local oxygen production. Moreover, the KORTUC I radiosensitization treatment is relatively inexpensive and the method can therefore be utilized worldwide for many patients suffering from superficially exposed and locally advanced radioresistant neoplasms such as malignant melanoma, malignant fibrous histiocytoma (MFH) and various types of sarcomas.
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PMID:New radiosensitization treatment (KORTUC I) using hydrogen peroxide solution-soaked gauze bolus for unresectable and superficially exposed neoplasms. 1849 41

The purpose of this study was to evaluate the impact of mitochondrial DNA (mtDNA) on radiation sensitivity under hypoxic conditions. The cell lines used were rho+ and rho0, which carry wild-type mtDNA and no mtDNA, respectively. The rho0 cells do not utilize oxygen because they lack the capacity to carry out oxidative phosphorylation. To confirm the role played by mtDNA in different cell lines, two types of cell line were used: human fibroblast and osteosarcoma cells. Radiosensitivity was evaluated by the colony formation assay, micronucleus (MN) formation assay and comet assay. Hypoxia lowered radiosensitivity in all three experiments for all four cell lines. Between rho+ and rho0 cells, no difference was found in the results from the colony formation assay and comet assay. However, higher MN formation was found in rho+ cells than in rho0 cells, not only under room air conditions in both the fibroblast and osteosarcoma cell lines, but also under hypoxic conditions. Therefore, although hypoxia lowers the radiosensitivity in general, the impact of mtDNA persists under hypoxic conditions.
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PMID:Impact of mitochondrial DNA on hypoxic radiation sensitivity in human fibroblast cells and osteosarcoma cell lines. 1849 63

Osteosarcoma is the most frequent primitive malignant tumor of the skeletal system and is characterized by an extremely aggressive clinical course that lacks an effective treatment. This study is the first to investigate the anti-cancer effects of a new isoflavone-derived 7-hydroxy-3',4'-benzoisoflavone (HBI) in human osteosarcoma cells. HBI-induced cell apoptosis in human osteosarcoma cell lines. The accumulation of reactive oxygen species (ROS) is a critical mediator in HBI induced cell death. HBI also induced apoptosis signal-regulating kinase 1 (ASK1) dephosphorylation, p38, JNK and p53 phosphorylation. Transfection with ASK1, p38 and JNK small interfering RNA (siRNA) antagonized HBI-induced cell apoptosis. HBI also triggered the mitochondrial apoptotic pathway, as indicated by a change in Bax/Bcl2 ratio. Bax knockdown using a Bax siRNA strategy reduced Bax expression and subsequent cell death. In addition, ASK1, p38 and JNK siRNA reduced HBI-induced p53 phosphorylation and Bax expression. These results suggest that the ROS-ASK1-p38/JNK-p53 and Bax pathway plays a critical role in HBI's anti-cancer effects.
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PMID:The novel isoflavone 7-hydroxy-3',4'-benzoisoflavone induces cell apoptosis in human osteosarcoma cells. 1860 92

Retinoic acid (RA), a biologically active derivative of vitamin A, has protective effects against damage caused by H(2)O(2) or oxygen-glucose deprivation in mesangial and PC12 cells. In cultured human osteosarcoma cells, RA enhances the expression of bone morphogenetic protein-7 (BMP7), a trophic factor that reduces ischemia- or neurotoxin-mediated neurodegeneration in vivo. The purpose of this study is to examine whether RA reduces ischemic brain injury through a BMP7 mechanism. We found that intracerebroventricular administration of 9-cis-retinoic acid (9cRA) enhanced BMP7 mRNA expression, detected by RT-PCR, in rat cerebral cortex at 24 hr after injection. Rats were also subjected to transient focal ischemia induced by ligation of the middle cerebral artery (MCA) at 1 day after 9cRA injection. Pretreatment with 9cRA increased locomotor activity and attenuated neurological deficits 2 days after MCA ligation. 9cRA also reduced cerebral infarction and TUNEL labeling. These protective responses were antagonized by the BMP antagonist noggin given 1 day after 9cRA injection. Taken together, our data suggest that 9cRA has protective effects against ischemia-induced injury, and these effects involve BMPs.
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PMID:9-Cis-retinoic acid reduces ischemic brain injury in rodents via bone morphogenetic protein. 1880 83

Osteosarcoma is the most common primary bone tumor associated with childhood and adolescence. In the present study, we investigated the anticancer effect of a new isoflavone derivative, 3',4'-dichloro-3-(3,4-dichlorophenylacetyl)-2,4,6-trihydroxydeoxybenzoin (DDTD) in human osteosarcoma cells. DDTD induced cell apoptosis in human osteosarcoma cell lines (including: U2OS, MG-63, Saos2 and ROS 17/2.8). We found that the accumulation of reactive oxygen species is a critical mediator in DDTD-induced cell death. DDTD induced apoptosis signal-regulating kinase 1 (ASK1) dephosphorylation and its dissociation from 14-3-3. Treatment of osteosarcoma cells with DDTD induced p38 and p53 phosphorylation. Transfection with ASK1, mitogen activated protein kinase (MAPK) kinase (MKK)3/6, and p38 small interfering RNA (siRNA) antagonized the DDTD-induced cell apoptosis. DDTD also triggered the mitochondrial apoptotic pathway, as indicated by a change in Bax/Bcl2 ratio and Caspase-9 activation. Bax knockdown using a Bax siRNA strategy reduced Bax expression and subsequent cell death. In addition, transfection of cells with ASK1, MKK3/6, and p38 siRNA reduced DDTD-induced p38 activation, p53 phosphorylation and Bax expression. These results suggest that DDTD generates reactive oxygen species and activates the ASK1-MKK3/6-p38-p53-Bax pathway to cause osteosarcoma cell death.
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PMID:DDTD, an isoflavone derivative, induces cell apoptosis through the reactive oxygen species/apoptosis signal-regulating kinase 1 pathway in human osteosarcoma cells. 1882 83


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