Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was performed to identify a potent and sequence-specific antisense oligonucleotide (ASO), to inhibit Hdm2 expression in human cancer cell lines and to study the downstream consequences. Ten chimeric 2'-O-methoxyethyl (MoE)-modified hemimers were synthesized that targeted various regions from the 5'- to the 3'-end of Hdm2 mRNA. The IC50 of the most potent ASO, NCH-4401, was subsequently determined and compared to the IC50 of a 2'-MoE-modified ASO, with a complete phosphorothioate backbone (NCH-4668), and to a 3 bp mismatched ASO (NCH4529). NCH4401 inhibited Hdm2 expression in SJSA-1 cells with an IC50 of 120 nm, whereas NCH-4668 was less potent with an IC50 of 180 nm. The mismatched control ASO was completely inactive, indicating a sequence-dependent mechanism of action of NCH-4401. NCH4401 was subsequently used to study the consequences of inhibiting Hdm2 expression in human osteosarcoma cells. NCH-4401 completely inhibited Hdm2 protein expression in SJSA-1 cells at a concentration of 300 nm, already 4 h after start of ASO treatment. At an ASO concentration of 300 nM, p53 protein was induced 12.5-fold and p21 was induced 8-fold over background levels, 24 h after start of ASO treatment. The dramatic induction of p53 in SJSA-1 cells prompted us to investigate whether the accumulation of p53 in these cells was followed by induction of apoptosis. However, no signs for apoptosis were detected in SJSA-1 cells, following induction of wild-type p53 using the Yopro method and the induction of caspase-3 activity. SJSA-1 cells were subsequently treated with NCH-4401 at different concentrations in combination with two well-known DNA-damaging agents, i.e. carboplatin and mitomycin C. Apoptosis induction following treatment of cells with DNA-damaging agents and NCH4401 was determined in parallel by measuring caspase-3 activation and uptake of the DNA dye Yopro. Carboplatin and mitomycin C together only slightly induced apoptosis in SJSA-1 cells to a factor of approximately 2-fold, as measured by the induction of caspase-3 activity. The downregulation of Hdm2 expression by NCH4401 did not induce apoptosis on its own and did not potentiate the mitomycin C/carboplatin-induced programmed cell death.
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PMID:Consequences of the inhibition of Hdm2 expression in human osteosarcoma cells using antisense oligonucleotides. 1171 35

Three prevalent mitochondrial DNA pathogenic mutations at positions 11778, 3460, and 14484, which affect different subunits of Complex I, cause retinal ganglion cell death and optic nerve atrophy in Leber's hereditary optic neuropathy (LHON). The cell death is painless and without inflammation, consistent with an apoptotic mechanism. We have investigated the possibility that the LHON mutation confers a pro-apoptotic stimulus and have tested the sensitivity of osteosarcoma-derived cybrid cells carrying the most common and severe mutations (11778 and 3460) to cell death induced by Fas. We observed that LHON cybrids were sensitized to Fas-dependent death. Control cells that bear the same mitochondrial genetic background (the J haplogroup) without the pathogenic 11778 mutation are no more sensitive than other controls, indicating that increased Fas-dependent death in LHON cybrids was induced by the LHON pathogenic mutations. The type of death was apoptotic by several criteria, including induction by Fas, inhibition by the caspase inhibitor zVAD-fmk (zVal-Ala-Asp-fluoro-methyl ketone), activation of DEVDase activity (Asp-Glu-Val-Asp protease), specific cleavage of caspase-3, DNA fragmentation, and increased Annexin-V labeling. These data indicate that the most common and severe LHON pathogenic mutations 11778 and 3460 predispose cells to apoptosis, which may be relevant for the pathophysiology of cell death in LHON, and potential therapy.
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PMID:Cells bearing mutations causing Leber's hereditary optic neuropathy are sensitized to Fas-Induced apoptosis. 1174 83

Apo2L/TRAIL is a member of the tumor necrosis factor (TNF) family of cytokines that induces death of cancer cells but not normal cells. Its potent apoptotic activity is mediated through its cell surface death domain-containing receptors, DR4 and DR5. Apo2L/TRAIL interacts also with 3 "decoy" receptors that do not induce apoptosis, DcR1, DcR2, which lack functional death domains, and osteoprotegerin (OPG). The aim of our study was to investigate the cytotoxic activity of Apo2L/TRAIL on established osteogenic sarcoma cell lines (BTK-143, HOS, MG-63, SJSA-1, G-292 and SAOS2) and in primary cultures of normal human bone (NHB) cells. When used alone, Apo2L/TRAIL at 100 ng/ml for 24 hr induced greater than 80% cell death in only 1 (BTK-143) of the 6 osteogenic sarcoma cell lines. In contrast, Apo2L/TRAIL-resistant cells were susceptible to Apo2L/TRAIL-mediated apoptosis in the presence of the anticancer drugs, Doxorubicin (DOX), Cisplatin (CDDP) and Etoposide (ETP) but not Methotrexate (MTX) or Cyclophosphamide (CPM). Importantly, neither Apo2L/TRAIL alone nor in combination with any of these drugs affected primary normal human bone cells under equivalent conditions. Apo2L/TRAIL-induced apoptosis, and its augmentation by chemotherapy in the resistant cell lines was mediated through caspase-8 and caspase-3 activation. Furthermore, Apo2L/TRAIL-induced apoptosis and its augmentation by chemotherapy was effectively inhibited by caspase-8 zIETD-fmk and caspase-3 zDEVD-fmk protease inhibitors and by the pan-caspase inhibitor zVAD-fmk. The pattern of basal Apo2L/TRAIL receptor mRNA expression, or expression of the intracellular caspase inhibitor FLICE-inhibitory protein, FLIP, could not be readily correlated with resistance or sensitivity to Apo2L/TRAIL-induced apoptosis. However, the augmentation of Apo2L/TRAIL effects by chemotherapy was associated with drug-induced up-regulation of death receptors DR4 and DR5 mRNA and protein. No obvious correlation was seen between the expression of OPG mRNA or protein and susceptibility of cells to Apo2L/TRAIL-induced apoptosis. Stable over-expression of a dominant negative form of the Fas-associated death domain protein (FADD) in the Apo2L/TRAIL-sensitive BTK-143 cells completely inhibited Apo2L/TRAIL-induced cell death. Our results indicate that chemotherapy and Apo2L/TRAIL act synergistically to kill cancer cells but not normal bone-derived osteoblast-like cells, which has implications for future therapy of osteosarcoma.
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PMID:Chemotherapeutic agents sensitize osteogenic sarcoma cells, but not normal human bone cells, to Apo2L/TRAIL-induced apoptosis. 1199 38

Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to produce an anti-proliferative and pro-apoptotic effect on different types of cancer cell lines. Previously, we demonstrated that high dose of NS-398 (100 microM), a selective cyclooxygenase-2 inhibitor, induced a cell cycle slowing or arrest and, in contrast to low dose (10 microM), a marked decrease in apoptosis in human 1547 osteosarcoma cells. In this study, we investigated particularly the effect of 100 microM NS-398 on p53 and p21 expression, caspase activities and nuclear factor-kappaB (NF-kappaB). We found a correlation between p53, p21 mRNA expression and NF-kappaB activation and, we observed an induction of heat shock protein 70 expression with a large decrease in caspase-3 activity after 100 microM NS-398 treatment. Moreover, the inhibition of apoptosis was correlated with an increase in bcl-2/bax ratio. Our new findings confirm the novel anti-apoptotic property of NS-398 at 100 microM, as we previously found, which contrasts to the described NS-398 pro-apoptotic effect on other cancer cell lines.
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PMID:The anti-apoptotic property of NS-398 at high dose can be mediated in part through NF-kappaB activation, hsp70 induction and a decrease in caspase-3 activity in human osteosarcoma cells. 1201 7

The cytokines IL-6, initially recognized as a regulator of immune and inflammatory response and IL-8, a potential regulator of angiogenesis, also regulate the growth of many tumor cells. Human cancer cells selected for multidrug resistance to common chemotherapeutic agents demonstrate increased expression of IL-6 and IL-8. To determine whether IL-6 or IL-8 overexpression contributes directly to the drug resistant phenotype, IL-6 or IL-8 cDNA were introduced into the paclitaxel sensitive human osteosarcoma cell line U-2OS using the pIRESneo bicistronic expression vector. Interleukin-6 and IL-8 transfectants were selected for either high IL-6 or IL-8 secretion and evaluated in drug resistance assays. Two IL-6 and two IL-8 secreting clones express IL-6 or IL-8 levels of 10 ng/ml and 1 ng/ml in culture, while parental U-2OS and pIRESneo vector transfected control cells express IL-6 and IL-8 levels of 0.005 ng/ml and 0.1 ng/ml, respectively. MTT cytotoxicity with IL-6 transfected cells demonstrates a five-fold increase in resistance to paclitaxel and a four-fold increase in resistance to doxorubicin as compared to U-2OS. There are no changes in mitoxantrone or topotecan resistance in the IL-6 transfectants as compared to parental U-2OS. Northern analysis of IL-6 transfectants demonstrates that the resistant phenotype is not related to increased levels of MDR-1, MRP-1, or LRP. Western analysis also confirms that P-glycoprotein levels are not altered in IL-6 transfectants. Further supporting an MDR-1 independent mechanism of drug resistance, verapamil cannot reverse paclitaxel resistance in transfected cells, findings further supported by rhodamine 123 exclusion data. Treatment of IL-6 transfected cells with paclitaxel, compared with drug-sensitive parental U-2OS, shows U-2OS(IL-6) are significantly more resistant to apoptosis induced by paclitaxel and exhibit decreased proteolytic activation of caspase-3. In contrast U-2OS(IL-8) transfectants demonstrate no appreciable increase in paclitaxel resistance when compared with parental cells. In summary, while both IL-6 and IL-8 are overexpressed in paclitaxel resistant cell lines, only IL-6 has the potential to contribute directly to paclitaxel and doxorubicin resistance in U-2OS. This resistance is through a non-MDR-1 pathway.
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PMID:Overexpression of IL-6 but not IL-8 increases paclitaxel resistance of U-2OS human osteosarcoma cells. 1202 4

The cytotoxic effect of the chemotherapeutic drug etoposide (VP-16) is thought to result from its ability to induce DNA damage and thereby to trigger apoptosis. Internucleosomal DNA fragmentation occurs late during apoptosis in many cell types. However, whereas human osteosarcoma cells undergo internucleosomal DNA fragmentation during staurosporine-induced apoptosis, they fail to do so in response to VP-16. Recently, we showed that these cells also do not express the poly(ADP-ribosyl)ation-regulated Ca(2+)- and Mg(2+)-dependent endonuclease DNAS1L3. The possibility that this deficiency underlies the failure of these cells to undergo internucleosomal DNA fragmentation in response to VP-16 was investigated. The proteolytic processing and consequent activation of procaspase-3, cleavage of the inhibitory subunit of DNA fragmentation factor, and the degradation of DNA into 50-kb fragments occurred similarly in osteosarcoma cells exposed to either staurosporine or VP-16. However, the additional processing of the 50-kb DNA fragments to oligonucleosomal fragments was not apparent in the VP-16-treated cells. Ectopic expression of DNAS1L3 conferred on osteosarcoma cells the ability to undergo VP-16-induced internucleosomal DNA fragmentation. Furthermore, expression of DNAS1L3 markedly potentiated the cytotoxic effect of VP-16 in these cells. Both DNAS1L3-mediated and staurosporine-induced internucleosomal DNA fragmentation were Ca(2+) dependent, but only the DNAS1L3-mediated DNA cleavage was blocked by expression of a caspase-3-resistant mutant of poly(ADP-ribose) polymerase-1. The present work results suggest a direct relation between the activity of a chemotherapeutic drug (VP-16) and a specific endonuclease (DNAS1L3). They also indicate that internucleosomal DNA fragmentation plays an active role in apoptosis and that the failure of cancer cells to undergo such DNA degradation may contribute to the development of resistance to chemotherapeutic drugs.
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PMID:The Poly(ADP-ribose) polymerase-1-regulated endonuclease DNAS1L3 is required for etoposide-induced internucleosomal DNA fragmentation and increases etoposide cytotoxicity in transfected osteosarcoma cells. 1215 52

Effective cell cycle completion requires both Myc and E2F activities. However, whether these two activities interact to regulate cell survival remains to be tested. Here we have analysed survival of inducible c-Myc-overexpressing cell lines derived from U2OS human osteosarcoma cells, which carry wild-type pRb and p53 and are deficient for p16 and ARF expression. Induced U2OS-Myc cells neither underwent apoptosis spontaneously nor upon reconstitution of the ARF-p53 axis and/or serum-starvation. However, they died massively when concomitantly exposed to inhibitors of E2F activity, including a constitutively active pRb (RbDeltacdk) mutant, p16, a stable p27 (p27T187A) mutant, a dominant-negative (dn) CDK2, or dnDP-1. Similar apoptotic effect was observed upon down-modulation of endogenous E2Fs through overexpression of E2F binding site oligonucleotides in U2OS-Myc cells, upon expression of RbDeltacdk or dnDP-1 in the Myc-amplified HL-60 (ARF-; p53-) human leukemia cells, and upon co-transfection of Myc and RbDeltacdk in SAOS-2 (ARF+; p53-) human osteosarcoma cells but not in human primary fibroblasts. Consistent with these results, a dnp53 mutant did not abrogate the Myc-induced apoptotic phenotype, which instead strictly depended on caspase-3-like proteases and on Myc transcriptional activity. Our data indicate that in contrast to normal cells, Myc-overexpressing human cancer cells need E2F activity for their survival, regardless of their ARF and p53 status, a notion that may have important implications for antineoplastic treatment strategies.
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PMID:E2F activity is essential for survival of Myc-overexpressing human cancer cells. 1222 53

Apo2 ligand (Apo2L/TRAIL) is a member of the tumor necrosis factor (TNF) cytokine family. Apo2L/TRAIL can selectively induce programmed cell death in transformed cells, although its wide tissue distribution suggests potential physiological roles. We have investigated the expression, in human osteoblast-like cells (NHBC), of Apo2L/TRAIL and the known Apo2L/TRAIL death receptors, DR4 and DR5, and the Apo2L/TRAIL decoy receptors, DcR-1, DcR-2, and osteoprotegerin (OPG). NHBC expressed abundant mRNA corresponding to each of these molecular species. Immunofluorescence staining demonstrated that Apo2L/TRAIL protein was abundant within the cytoplasm of NHBC and OPG was strongly expressed at the cell surface. DR5 and DcR-2 were present in the cell membrane and cytoplasm and DcR-1 was confined to the nucleus. DR4 staining was weak. Neither Apo2L/TRAIL alone, nor in combination with chemotherapeutic agents of clinical relevance to treatment of osteogenic sarcoma, induced cell death in NHBC, as assessed morphologically and by activation of caspase-3. In contrast, the human osteogenic sarcoma cell lines, BTK-143 and G-292, were sensitive to exogenous Apo2L/TRAIL alone, and to the combined effect of Apo2L/TRAIL/cisplatin and Apo2L/TRAIL/doxorubicin treatments, respectively. In NHBC, we observed strong associations between the levels of mRNA corresponding to the pro-apoptotic molecules, Apo2L/TRAIL, DR4, and DR5, and those corresponding to pro-survival molecules, DcR-1, DcR-2, OPG, and FLIP, suggesting that the balance between pro-survival and pro-apoptotic molecules is a mechanism by which NHBC can resist Apo2L/TRAIL-mediated apoptosis. In contrast, osteogenic sarcoma cells had low or absent levels of DcR-1 and DcR-2. These results provide a foundation to explore the role of Apo2L/TRAIL in osteoblast physiology. In addition, they predict that therapeutic use of recombinant Apo2L/TRAIL, in combination with chemotherapeutic agents to treat skeletal malignancies, would have limited toxic effects on normal osteoblastic cells.
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PMID:Human osteoblasts are resistant to Apo2L/TRAIL-mediated apoptosis. 1239 39

In bone, a large proportion of osteoblasts, the cells responsible for deposition of new bone, normally undergo programmed cell death (apoptosis). Because mechanical loading of bone increases the rate of new bone formation, we hypothesized that mechanical stimulation of osteoblasts might increase their survival. To test this hypothesis, we investigated the effects of fluid shear stress (FSS) on osteoblast apoptosis using three osteoblast cell types: primary rat calvarial osteoblasts (RCOB), MC3T3-E1 osteoblastic cells, and UMR106 osteosarcoma cells. Cells were treated with TNF-alpha in the presence of cyclohexamide (CHX) to rapidly induce apoptosis. Osteoblasts showed significant signs of apoptosis within 4-6 h of exposure to TNF-alpha and CHX, and application of FSS (12 dyne/cm(2)) significantly attenuated this TNF-alpha-induced apoptosis. FSS activated PI3-kinase signaling, induced phosphorylation of Akt, and inhibited TNF-alpha-induced activation of caspase-3. Inhibition of PI3-kinase, using LY294002, blocked the ability of FSS to rescue osteoblasts from TNF-alpha-induced apoptosis and blocked FSS-induced inhibition of caspase-3 activation in osteoblasts treated with TNF-alpha. LY294002 did not, however, prevent FSS-induced phosphorylation of Akt suggesting that activation of Akt alone is not sufficient to rescue cells from apoptosis. This result also suggests that FSS can activate Akt via a PI3-kinase-independent pathway. These studies demonstrate for the first time that application of FSS to osteoblasts in vitro results in inhibition of TNF-alpha-induced apoptosis through a mechanism involving activation of PI3-kinase signaling and inhibition of caspases. FSS-induced activation of PI3-kinase may promote cell survival through a mechanism that is distinct from the Akt-mediated survival pathway.
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PMID:Fluid shear stress inhibits TNF-alpha-induced apoptosis in osteoblasts: a role for fluid shear stress-induced activation of PI3-kinase and inhibition of caspase-3. 1249 58

Doxorubicin (DOX) is a common anticancer drug. The mechanisms of DOX induced apoptosis and the involvement of reactive oxygen species (ROS) in apoptotic signaling were investigated in p53-null human osteosarcoma Saos-2 cells. Accumulation of pre-G1 phase cells and induction of DNA laddering, which are the hallmarks of apoptosis, were detected in cells at 48 h upon DOX treatment. Furthermore, DOX increased the intracellular hydrogen peroxide and superoxide levels, followed by mitochondrial membrane depolarization, cytochrome c release, caspase-3 activation, prior to DNA laddering in Saos-2 cells. In addition, DOX treatment also upregulated Bax and downregulated Bcl-2 levels in the cells. The role of ROS in DOX induced cell death was confirmed by the suppression effect of catalase on DOX induced ROS formation, mitochondrial cytochrome c release, procaspase-3 cleavage, and apoptosis in Saos-2 cells. The catalase treatment however only suppressed DOX induced Bax upregulation but had no effect on Bcl-2 downregulation. Results from the present study suggested that ROS might act as the signal molecules for DOX induced cell death and the process is still functional even in the absence of p53.
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PMID:Reactive oxygen species mediate doxorubicin induced p53-independent apoptosis. 1289 28


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