Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cyclooxygenase-2 (COX-2) displays anti-apoptotic functions related to angiogenesis or blocking of bcl-2 functions. COX-2 overexpression has been found in various human malignancies, including esophageal squamous cell carcinoma (ESCC). The present study examined correlations between expression of COX-2 mRNA and ESCC responses to chemoradiotherapy (CRT). Expression of COX-2 mRNA obtained from 29 biopsy specimens before CRT was quantified using reverse transcriptase-polymerase chain reaction (RT-PCR) using Sybr Green I on the Roche LightCycler system. CRT comprised 5-fluorouracil plus cisplatin and 40 Gy of radiation. Mean COX-2 mRNA score was significantly higher in tumors (1222) than in normal epithelium (50; p=0.05). Expression of COX-2 mRNA was high in 14 patients, low in 8 and absent in 7. The effective response to CRT was achieved in 18 patients. Mean COX-2 mRNA score was significantly higher in ineffective cases (2910) than in effective cases (190; p<0.05). CRT was more effective in patients with low COX-2 mRNA expression than in those with high expression. COX-2 mRNA expression in biopsy specimens was closely related to CRT effectiveness. Examination of COX-2 mRNA expression is useful for predicting the effect of CRT in patients with ESCC.
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PMID:Predictive value of COX-2 for the effect of chemoradiotherapy on esophageal squamous cell carcinoma. 1575 44

The influence of amifostine alone and in combination with doxorubicin, cytarabine, and etoposide on the cell growth and on bcl-2, bax and p65 gene expression was investigated in human acute promyelocytic leukemia cell line HL-60. No or very little influence of the exposure of HL-60 cells to amifostine (10(-6) to 10(-2) M) on cell proliferation was shown. Proliferation of HL-60 cells exposed to doxorubicin, cytarabine, or etoposide dropped down with increasing doses of these drugs. Only in the case of doxorubicin, more effective inhibition of HL-60 cell growth was observed when combination of doxorubicin, cytarabine or etoposide with amifostine was used. Cytotoxic effect of cytarabine or etoposide was not reduced by amifostine. The lowering of the cytotoxic index (IC50) was observed only when HL-60 cells were preincubated with amifostine followed by doxorubicin treatment. IC50 was estimated as 2.1 x 10(-7) M and 0.9 x 10(-7) M for doxorubicin and doxorubicin with amifostine, respectively. This effect was accompanied by the induction of caspase 3 activity. HL-60 cells treated with doxorubicin alone showed about 35-fold increase in caspase 3 activity. The enzyme activity was stimulated by combination of doxorubicin with amifostine up to 94 times. Furthermore, the expression of bcl-2 and bax genes involved in apoptosis as well as tumor-associated p65 gene were determined. Semiquantitative reverse transcriptase polymerase chain reaction showed a decrease in bcl-2 and an increase in bax and p65 expression in HL-60 cells treated with doxorubicin in combination with amifostine when compared with the cells treated only with doxorubicin. Amifostine may potentiate doxorubicin therapeutic efficiency in human acute promyelocytic leukemia cells.
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PMID:Induction of caspase 3 activity, bcl-2 bax and p65 gene expression modulation in human acute promyelocytic leukemia HL-60 cells by doxorubicin with amifostine. 1598 19

Our previous study reported that oxysterol cholestane-3beta,5 alpha, 6 beta-triol (Triol) induced vascular smooth muscle cells (VSMCs) apoptosis, which was inhibited by selenium pretreatment. To further investigate the mechanisms of the inhibition, the glutathione peroxidase (GPx) activity, the total antioxidant capacity (T-AOC), the total superoxide dismutase (SOD) activity, and the level of lipid peroxidation (the content of malondialdehyde, MDA) of VSMCs were measured, and fluidity of cell membrane, reactive oxygen species (ROS) level, the reduction of mitochondrial membrane potential (Delta psi(m)), and the intracellular Ca(2+) in single cell were detected using several fluorescence indicators. Meanwhile, the mRNA levels of c-myc, bcl-2, GPx, and thioredoxin reductase (TR) were measured by reverse transcriptase polymerase chain reaction (RT-PCR) analysis. The results showed that the decrease of GPx activity, T-AOC, SOD activity, the fluidity of cell membrane, the Delta psi(m), and the mRNA expression of c-myc, bcl-2, GPx, and TR of VSMCs and the increase of MDA, ROS generation, and intracellular Ca(2+), significantly induced by Triol (10 microM, 24h) were inhibited to a different extent, respectively, when cells were pretreated with sodium selenite (50 nM, 12 or 24h) before exposure to Triol. These effects were time dependent and enhanced with prolongation of the time of pretreatment. In conclusion, the results in the present work showed that the mechanism of selenium inhibition of cell apoptosis induced by oxysterols in rat VSMCs was related with the antioxidation of selenoproteins.
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PMID:Mechanisms of selenium inhibition of cell apoptosis induced by oxysterols in rat vascular smooth muscle cells. 1603 82

Telomerase, a reverse transcriptase that maintains telomere length, is highly activated in tumor cells and practically absent in somatic cells and hence considered a potential marker for tumorigenesis. A connection between telomerase activity and resistance to apoptosis has been established. Telomerase, therefore, has been proposed to represent a novel and potentially selective target for cancer therapy. Several synthetic compounds have been developed in recent years with a view to inhibit telomerase activity with telomere shortening below a critical length resulting in apoptosis. Such compounds are always highly toxic. Many plant-derived products act through the induction of apoptosis as a mechanism to suppress carcinogenesis. Curcumin, a phenolic compound isolated from the rhizome of the plant Curcuma longa Linn., has been reported to possess anti-tumor, apoptotic and anti-angiogenic properties. Apoptosis has emerged as the major mechanism by which anti-tumor agents eliminate pre-neoplastic cells or cells progressed to malignancy. The present study was undertaken to examine the mechanism of curcumin-induced apoptosis in human leukemia cell line K-562 with particular emphasis on the role of curcumin on telomerase activity. Induction of apoptosis by curcumin is initiated by the release of cytochrome c from mitochondria into the cytosol, and evidenced by the increase in DNA content in the sub-G1 region as obtained from FACS analysis. Apoptosis is mediated by the activation of caspases 3 and 8, up-regulation of the apoptotic gene bax with concomitant down-regulation of the anti-apoptotic gene bcl-2. Using TRAP assay it has been observed that curcumin inhibits telomerase activity in a dose and time-dependent manner, the inhibition being due to suppression of translocation of telomerase reverse transcriptase (TERT), a catalytic subunit, from cytosol to nucleus. Most significantly, the inhibition of telomerase activity by curcumin correlates with several parameters of apoptosis. The results suggest that telomerase status plays an important role in the induction of apoptosis in K-562 cells by curcumin.
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PMID:Inhibition of telomerase activity and induction of apoptosis by curcumin in K-562 cells. 1644 49

Using a rat model of moderate hypothermic (26 degrees C-28 degrees C) cardiopulmonary bypass (CPB) with hemodilution, we investigated hippocampal apoptotic gene expression and neuronal apoptosis up to 6 h after CPB. The CPB was performed on male rats (380-400 g) under general anesthesia with isoflurane and fentanyl. The right atrium and tail artery were cannulated, and a peristaltic pump and membrane oxygenator were used for CPB. Two groups were studied: Group 1 consisted of fasted rats (n = 15) subjected to 60 min of moderate hypothermic nonpulsatile CPB; Group 2 consisted of sham-operated rats (n = 15). At 1 h after CPB, in 6 rats per group, hippocampus was processed for the apoptotic gene (bcl-2 and bax) messenger RNAs detection by reverse transcriptase polymerase chain reaction, and messenger RNA expression was determined by the ratio of the polymerase chain reaction product of bcl-2 or bax to the beta-actin gene. At 6 h after CPB, in 6 rats per group, hippocampus expression of Bcl-2 and bax protein was determined by immunohistochemistry, and neuronal apoptosis was detected by TUNEL. At 6 h after CPB, in three rats per group, changes in hippocampal CA1 neuronal ultra structure were determined with electron microscopy. Group 1 had increased ratios of bcl-2/beta-actin, bax/beta-actin, and bax/bcl-2 mRNA at 1 h after CPB (bcl-2/beta-actin, 0.82 +/- 0.14 versus 0.63 +/- 0.07; P = 0.03; bax/beta-actin, 1.04 +/- 0.14 versus 0.56 +/- 0.03; P = 0.00; bax/bcl-2, 1.31 +/- 0.12 versus 0.84 +/- 0.09; P = 0.02; Group 1 versus Group 2, respectively). Group 1 had increased bcl-2 and bax protein expression in hippocampal CA1 region at 6 h after CPB (bcl-2, 0.18 +/- 0.05 versus 0.09 +/- 0.01; P = 0.02; bax, 0.20 +/- 0.06 versus 0.04 +/- 0.02; P = 0.01; Group 1 versus Group 2, respectively). Group 1 had increased TUNEL staining in hippocampus CA1 at 6 h after CPB (0.14 +/- 0.02 versus 0.03 +/- 0.01; P = 0.00; Group 1 versus Group 2, respectively). In Group 1 CA1 hippocampus neurons, ultra-structural changes consistent with apoptosis occurred. In rats, moderate hypothermic CPB with hemodilution is associated with CA1 hippocampus bax and bcl-2 gene expression and neuronal apoptosis during the early post-CPB recovery period.
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PMID:Hippocampus bcl-2 and bax expression and neuronal apoptosis after moderate hypothermic cardiopulmonary bypass in rats. 1655 91

We have previously reported functional alterations in vitro in the hematopoietic compartment of patients with diffuse large B-cell lymphoma (DLBCL). In the present study, we assessed the presence of molecular alterations in hematopoietic cells derived from DLBCL marrow. Accordingly, the expression of four genes (i.e. ice, bcl-2, c-myc and p53) was assessed both, at the mRNA and protein levels, in three cell populations: (i) population I, consisting of morphologically recognizable precursor and mature cells; (ii) population II, enriched for CD34+ Lineage-negative (Lin-) cells; and (iii) population III, enriched for CD34+ CD38- Lin- cells. By using a multiplex reverse transcriptase-polymerase chain reaction system, we observed reduced expression of bcl-2 in population I, and c-myc in populations I and II from lymphoma marrow compared to their normal counterparts. On the other hand, expression of ice and p53 was not significantly different when comparing normal and DLBCL samples. At the protein level, all four molecules were expressed in a higher proportion of samples from DLBCL patients than in marrow samples from normal subjects. Interestingly, these proteins were expressed predominantly in primitive cells (population III), whereas the proportion of positive samples was reduced in population II, and even more in population I. Taken together, our results indicate that, in DLBCL, molecular alterations are present in hematopoietic cells from bone marrow, including morphologically recognizable precursor and mature cells, as well as primitive hematopoietic progenitors (CD34+ cells). To date, the physiological implications of these alterations are still unclear, and further studies should be undertaken to address this issue.
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PMID:Expression of ice, bcl-2, c-myc and p53 in different bone marrow cell populations from patients with diffuse large B-cell lymphoma. 1669 May 25

Curcumin (diferuloylmethane), a natural cancer chemopreventive compound, has been tested for its action in acute myeloblastic leukemia cell line HL-60. The results clearly show that curcumin induces apoptosis in these cells as evidenced by the release of cytochrome c from mitochondria to the cytosol and increase in the DNA content in sub G1 region as observed in FACS analysis. Apoptosis is apparently mediated by up-regulation of apoptotic gene bax and simultaneous down-regulation of anti-apoptotic gene bcl-2 followed by activation of caspases 3 and 8 and degradation of PARP. Telomerase, a reverse transcriptase, has been found to be activated in more than 80% of human cancers and, therefore, can be considered as a potential marker for tumorigenesis. Certain natural compounds have the potential of inhibiting telomerase activity leading to suppression of cell viability and induction of apoptosis. The present study shows that curcumin-induced apoptosis coincides with the inhibition of telomerase activity in a dose dependent manner.
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PMID:Curcumin-induced apoptosis in human leukemia cell HL-60 is associated with inhibition of telomerase activity. 1709 85

Crocin, extracted and purified from Gardenia jasminoids Ellis in our laboratory, has been reported to have antioxidative, hypolipidaemic and anti-atherosclerorotic effects. However, the underlying molecular mechanisms by which crocin acts as a cytoprotective agent remain to be elucidated. In the present study, we examined the mechanisms of crocin, the digentiobiosyl ester of crocetin, on bovine aortic endothelial cell apoptosis induced by hydrogen peroxide (H2O2). The cells were obtained from the thoracic aorta of newborn calves, and apoptosis was induced by 200 microM H2O2. Before addition of H2O2, the cells were pretreated with different concentrations of crocin for 6 hr. After incubation of the cells with H2O2, a comparative reverse transcriptase-polymerase chain reaction-based repeated amplification protocol assay was used to determine the ratio of bcl-2/bax mRNA expression, and cells loaded with fluo-3/AM were subjected to laser scanning confocal microscopy for detection of intracellular calcium ([Ca2+]i) levels. Treatment of the cells with H2O2 alone decreased the ratio of bcl-2/bax expression to almost twice of those of untreated cells (from 0.33+/-0.05 to 0.16+/-0.02). In the presence of 1 and 10 microM crocin, the ratios were enhanced when compared with H2O2 alone respectively (from 0.16+/-0.02 to 0.58+/-0.04, 1.18+/-0.13). The treatment of cells with crocin alone had little effect on the value of this ratio. In the presence or absence of extracellular Ca2+, H2O2 could induce intracellular calcium elevation not only in the elevation presence of extracellular Ca2+ (Hanks), but also without extracellular calcium present (D-Hanks). But the extent of [Ca2+]i under conditions lacking extracellular calcium is less. Crocin concentration dependently inhibited the [Ca2+]i elevation induced by H2O2 under these two conditions. Our data suggest that crocin may exert anti-atherosclerotic effects by increasing the expression ratio of bcl-2/bax, as a result, inhibiting the bovine aortic endothelial cell apoptosis that plays an important role in the initiation and progression of atherosclerosis.
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PMID:Increased expression ratio of Bcl-2/Bax is associated with crocin-mediated apoptosis in bovine aortic endothelial cells. 1721 8

This study was purposed to investigate the reversal effect of sodium selenite on multidrug resistance in adriamycin-resistant leukemic cell line K562/ADR and its mechanisms. The cytotoxicity and the reversal effect of sodium selenite on K562/ADR cells were assayed by MTT method; the apoptosis rate of K562 and K562/ADR cells were detected by flow cytometery, the mRNA expressions of mdr1 and bcl-2 were measured by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). The results showed that 10 micromol/L sodium selenite significantly increased the cytotoxicity of adriamycin to K562/ADR cell and the reverse index (RI) was 2.31; the early apoptosis rate of K562 cells was elevated after treatment with 5 micromol/L Na(2)SeO(3) for 48 hours; and the medium-term and late apoptosis rate was elevated after treatment with both 5 and 10 micromol/L Na(2)SeO(3) for 48 and 72 hours. Both doses of 5 and 10 micromol/L Na(2)SeO(3) increased the early apoptosis rate of K562/ADR at 48 hours, and also increased the medium-term and late apoptosis rate after treating for 48 and 72 hours. The apoptosis rate was higher at dose of 10 micromol/L than that at 5 micromol/L, the apoptosis rate at 72 hours also was higher than that at 48 hours. The expressions of mdr1 mRNA and bcl-2 mRNA were decreased significantly by 10 micromol/L sodium selenite. It is concluded that sodium selenite can reverse the multidrug resistance in K562/ADR partially by down-regulating the expressions of mdr1 mRNA and bcl-2 mRNA, and increasing apoptosis rate of K562/ADR cells.
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PMID:[Reversal effect of sodium selenite on multidrug resistance in K562/ADR cell line and its mechanisms]. 1770 98

Two cases of primary prostatic synovial sarcoma presenting as a prostatic mass are presented in patients aged 44 and 46 years. Histologically, both tumors were mainly composed of uniform spindle cells forming interlacing fascicles. Clusters of immature epithelioid cells were also observed among the spindle cells in case 1. Immunohistochemically, the tumor cells of both cases were strongly positive for vimentin, bcl-2, CD99, and E-cadherin, as well as focally positive for cytokeratin. However, they were negative for prostate-specific antigen, S-100 protein, CD34, CD117, muscle-specific actin, desmin, and calretinin. The presence of an SYT-SSX gene fusion resulting from t(X;18) was demonstrated from paraffin blocks by reverse transcriptase polymerase chain reaction in both cases. To the authors' knowledge, these represent the fifth and sixth reported cases of prostatic synovial sarcoma. Accurate diagnosis depends on morphologic and immunohistochemical examination and proper molecular analysis.
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PMID:Primary synovial sarcoma of the prostate: report of 2 cases and literature review. 1838 92


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