Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Arsenic trioxide (ATO) has been found to be an effective treatment for acute promyelocytic leukemia patients and is being tested for treating other hematologic malignancies. We have previously shown that AML1/MDS1/EVI1 (AME), a fusion gene generated by a t(3;21)(q26;q22) translocation found in patients with chronic myelogenous leukemia during blast phase, myelodysplastic syndrome, or acute myelogenous leukemia (AML), impairs hematopoiesis and eventually induces an AML in mice. Both fusion partners of AME, AML1 and MDS1/EVI1, encode transcription factors and are also targets of a variety of genetic abnormalities in human hematologic malignancies. In addition, aberrant expression of ectopic viral integration site 1 (EVI1) has also been found in solid tumors, such as ovarian and colon cancers. In this study, we examined whether ATO could target AME and related oncoproteins. We found that ATO used at therapeutic levels degrades AME. The ATO treatment induces differentiation and apoptosis in AME leukemic cells in vitro as well as reduces tumor load and increases the survival of mice transplanted with these cells. We further found that ATO targets AME via both myelodysplastic syndrome 1 (MDS1) and EVI1 moieties and degrades EVI1 via the ubiquitin-proteasome pathway and MDS1 in a proteasome-independent manner. Our results suggest that ATO could be used as a part of targeted therapy for AME-, AML1/MDS1-, MDS1/EVI1-, and EVI1-positive human cancers.
 ...
PMID:Targeted degradation of the AML1/MDS1/EVI1 oncoprotein by arsenic trioxide. 1714 82

Arsenic trioxide (As2O3) induces apoptosis in certain types of cancer cells. But the detailed mechanisms of As2O3 efficacy are not completely known. Here we demonstrate that As2O3 has a therapeutic effect on cervical cancer in vitro and in vivo. We investigated the As2O3-induced apoptosis in various cervical cancer cells. The apoptosis was triggered by mitochondrial pathway and associated with dissociation of Bcl-2 from Bax and VDAC, then the release of cytochrome c from Bax and VDAC channel, resulting in the activation of caspase-9 and caspase-3. The overexpression of Bcl-2 counteracted the As2O3-mediated apoptosis. The As2O3 treatment also resulted in an increased M phase cell cycle distribution by inducing microtubule polymerization. Two independent death-signaling pathways in cervical cancer cells were activated, one dominated by JNK/p38/GADD45 and one by p53 signals. Further investigation involving assessment of As2O3 on tumor cell growth in mice indicated that As203 also inhibited in vivo tumor growth. As2O3 as an inhibitor of cervical cancer proliferation both in vitro and in vivo suggests a potential clinical application in cervical cancer therapies.
 ...
PMID:Therapeutic effect of arsenic trioxide (As2O3) on cervical cancer in vitro and in vivo through apoptosis induction. 1737 90

The majority of aggressive forms of the childhood tumor neuroblastoma can with current treatment protocols not be cured and possess a major challenge in pediatric oncology. After initial rounds of chemotherapy, surgery and irradiation, which in most cases result in tumor regression, these aggressive neuroblastomas relapse and frequently develop drug resistance. As approximately 50% of the children with neuroblastoma have an aggressive form, there is a compelling demand for new treatment strategies. Arsenic trioxide has the capacity to kill multidrug-resistant neuro-blastoma cells in vitro and in vivo and the drug is currently being evaluated in clinical trials. In this report we discuss the background to the use of arsenic trioxide in cancer therapy and the currently known mechanisms by which arsenic trioxide kills human neuroblastoma cells.
 ...
PMID:Arsenic trioxide and neuroblastoma cytotoxicity. 1754 41

Arsenic trioxide (As2O3) is an effective therapy in acute promyelocytic leukemia (APL), but its use in other malignancies is limited by the higher concentrations required to induce apoptosis. We have reported that trolox, an analogue of alpha-tocopherol, increases As2O3-mediated apoptosis in a variety of APL, myeloma and breast cancer cell lines, while non-malignant cells may be protected. In the present study, we extended previous results to show that trolox increases As2O3-mediated apoptosis in the P388 lymphoma cell line in vitro, as evidenced by decrease of mitochondrial membrane potential and release of cytochrome c. We then sought to determine whether this combination can enhance antitumor effects while protecting normal cells in vivo. In BDF1 mice, trolox treatment decreased As2O3-induced hepatomegaly, markers of oxidative stress and hepatocellular damage. In P388 tumor-bearing mice, As2O3 treatment prolonged survival, and the addition of trolox provided a further significant increase in lifespan. In addition, the combination of As2O3 and trolox inhibited metastatic spread, and protected the tumor-bearing mice from As2O3 liver toxicity. Our results suggest, for the first time, that trolox might prevent some of the clinical manifestations of As2O3-related toxicity while increasing its pro-apoptotic capacity and clinical efficacy in hematological malignancies.
 ...
PMID:Trolox enhances the anti-lymphoma effects of arsenic trioxide, while protecting against liver toxicity. 1769 Jun 99

Arsenic trioxide (ATO, Trisenox) is a potent anti-vascular agent and significantly enhances hyperthermia and radiation response. To understand the mechanism of the anti-tumor effect in vivo we imaged the binding of a fluorescently-labeled poly-caspase inhibitor (FLIVO) in real time before and 3 h or 24 h after injection of 8 mg/kg ATO. FSaII tumors were grown in dorsal skin-fold window chambers or on the rear limb and we observed substantial poly-caspase binding associated with vascular damage induced by ATO treatment at 3 and 24 h after ATO injection. Flow cytometric analysis of cells dissociated from the imaged tumor confirmed cellular uptake and binding of the FLIVO probe. Apoptosis appears to be a major mode of cell death induced by ATO in the tumor and the use of fluorescently tagged caspase inhibitors to assess cell death in live animals appears feasible to monitor and/or confirm anti-tumor effects of therapy.
 ...
PMID:Use of a fluorescently labeled poly-caspase inhibitor for in vivo detection of apoptosis related to vascular-targeting agent arsenic trioxide for cancer therapy. 1799 96

Arsenic trioxide (ATO) has been recommended for the treatment of refractory cases of acute promyelocytic leukemia (APL). Recent studies in our laboratory indicated that oxidative stress plays a key role in ATO-induced cytotoxicity in human leukemia (HL-60) cells. In the present investigation, we performed the MTT assay and trypan blue exclusion test for cell viability. We also performed the thiobarbituric acid test to determine the levels of malondialdehyde (MDA) production in HL-60 cells coexposed to either ascorbic acid (AA) and ATO or to n-acetyl-L-cysteine (NAC) and ATO. The results of MTT assay indicated that AA exposure potentiates the cytotoxicity of ATO in HL-60 cells, as evidenced by a gradual increase in MDA levels with increasing doses of AA. In contrary, the addition of NAC to ATO-treated HL-60 cells resulted in a dose-dependent decrease of MDA production. From these results, we conclude that the addition of the AA to ATO-treated HL-60 cells enhances the formation of reactive oxygen species (ROS), whereas the addition of NAC under the same experimental condition significantly (p < .05) decreases the level of ROS formation. On the basis of these direct in vitro findings, our studies provide evidence that AA may extend the therapeutic spectrum of ATO. The coadministration of NAC with ATO shows a potential specificity for tumor cells, indicating that it may not enhance the clinical outcome associated with ATO monotherapy in vivo.
 ...
PMID:Differential effect of ascorbic acid and n-acetyl-L-cysteine on arsenic trioxide-mediated oxidative stress in human leukemia (HL-60) cells. 1841 92

Arsenic trioxide (ATO) is a potent anti-tumor agent used to treat acute promyelocytic leukemia (APL), and more recently solid tumors including gliomas. However, the dose of ATO required to suppress gliomas is markedly higher than that used to treat APL, which leads to toxicity and undesirable side-effects, even though the local concentration of ATO in brains is relatively low after systemic administration. In an attempt to minimize the toxicity, enhance the penetrating activity across the blood-brain barrier, and reduce enzyme degradation, we prepared ATO encapsulated in liposomes, and investigated its therapeutic effect on C6 gliomas established in rat brains. The prepared ATO liposomes were stable at room temperature for 3 days and the latency rate was over 90% within 72 h. Intravenous injection of ATO liposomes led to a much higher concentration of ATO (5- fold, compared with ATO solution) in rat brains, resulting in inhibition of C6 gliomas in brains and prolonging the survival of rats bearing brain gliomas. ATO-liposome therapy resulted in fewer side effects, compared with free ATO solution. ATO-liposome therapy inhibited tumor angiogenesis by downregulating the expression of vascular endothelial growth factor (VEGF), and inducing cell apoptosis. The results warrant future investigation of the use of ATO encapsulated in liposomes to treat gliomas.
 ...
PMID:Intravenous administration of arsenic trioxide encapsulated in liposomes inhibits the growth of C6 gliomas in rat brains. 1846 54

Arsenite has been well-proved to act as both an environmental carcinogen as well as a tumor therapeutic agent. AP-1 is one of the transcription factors that can be induced upon arsenite stimulation. However, the study on the mechanism and the function of the arsenite-induced AP-1 transactivation remains far complete. Here we demonstrated that high dose of arsenite induced apoptotic response in mouse fibroblasts correlating with AP-1 transactivation, which events were mediated by both IKKalpha and IKKbeta, two major protein kinases responsible for NF-kappaB activation. In addition, the regulatory effect of IKKs on the arsenite-induced AP-1 activation was delivered by sequential induction of GADD45alpha expression and the activation of MAPKK (MKK3/4/6) and MAPK (JNK and p38K)-dependent pathways. We further provided evidence that p50, but not p65 subunit of NF-kappaB, was involved in GADD45alpha induction and the subsequent MAPKK/MAPK/AP-1 activation under arsenite exposure, while functional NF-kappaB induced by arsenite stimulation consisted of p65 but not of p50 subunit. Therefore, we concluded that both IKKalpha and IKKbeta can mediate arsenite-induced AP-1 transactivation through NF-kappaB activity-independent manner.
 ...
PMID:Both IKKalpha and IKKbeta are implicated in the arsenite-induced AP-1 transactivation correlating with cell apoptosis through NF-kappaB activity-independent manner. 1850 47

Arsenic trioxide (As2O3) shows a significant therapeutic effect upon acute promyelocytic leukemia (APL) and can induce the apoptosis of NB4 cells, which attracts scholars' great attention. Especially, the therapeutic effect on solid carcinoma has been paid more close attention to. The present study is to evaluate the effect of As2O3 on human colorectal carcinoma cells (LS-174T cell) and the activity of telomerase in vitro and in vivo. This research made use of the electron microscope, polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), fluorescence-activated cell sorter (FACS), MTT in vitro and in vivo (LS-174T xenograft model of nude mice). With the increasing concentration of As2O3, the ratio of living cells to dead cells decreased significantly, and the IC50 value was 5.23micromol/L; cells of the experimental groups endured a series of morphological changes similar to the features of apoptosis. Apoptosis curve of FACS pictures appeared after 24h, and the cells showed apoptosis in a time-dependent manner; As2O3 can inhibit the activity of telomerase of the cell extraction, obviously, in a concentration-dependent and time-dependent manner after 24h. As to the inhibition impact of As2O3 on the xenograft model of nude mice in the two indexes, tumor volume and weight, there was a significant difference between As2O3 and the control group; there was no difference between As2O3 and the fluorouracil (5-FU) group; in the group of peritoneal injections of As2O3, the cancer cells connected loosely with each other, nucleus changed markedly, and heterochromatin concentrated under the nucleus membrane. From the in vitro and in vivo experiment, we can see that As2O3 inhibited LS-174T cell growth mainly by inducing cell apoptosis, partly by the inhibition of telomerase activity.
 ...
PMID:Inhibition on LS-174T cell growth and activity of telomerase in vitro and in vivo by arsenic trioxide. 1860 28

Arsenic is a well-known human skin carcinogen whose mechanism of action remains to be elucidated. In this work using cultured human epidermal cells, arsenite suppressed accumulation of the transcriptionally active intracellular domain of Notch1. The cells responded to an active peptide from the Notch1 ligand, Jagged1, with increased levels of differentiation marker mRNAs and decreased colony-forming ability. Arsenite suppressed Jagged1 effects and expression of Jagged1 mRNA as well. Moreover, exposure of the cells to a gamma-secretase inhibitor prevented Notch1 processing, decreased cell size and differentiation marker expression, and increased proliferative potential, all effects that occur with arsenite treatment. Thus, arsenite action in suppressing keratinocyte differentiation while maintaining germinative capability could be due to inhibition of Notch1 signaling subsequent to ligand binding. This work also revealed that such arsenite action depends upon epidermal growth factor receptor kinase activity. These findings may help to explain how arsenite, by decreasing generation of the tumor suppressor Notch1, contributes to skin carcinogenesis.
 ...
PMID:Arsenite suppresses Notch1 signaling in human keratinocytes. 1863 35


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>