Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was undertaken to determine whether small cell lung cancer (SCLC) cell lines produce immunosuppressive factors and, if they do, to characterize the factors. The supernatants of SCLC cell lines, H69 and N857, inhibited not only the blastogenic response of human peripheral blood lymphocytes (PBL) to phytohemagglutinin or concanavalin A, but also the cytotoxic activity of lymphokine-activated killer cells. Neither was inhibited by supernatants from non-SCLC cell lines PC9, QG56, and A549. The immunosuppressive activity of H69 supernatant was stable upon heating to 56 degrees C for 60 min, but labile when heated to 70 degrees C for 10 min. The activity was abolished after dialysis at pH 2.0 or pH 11.0, but not at pH 4.5 or pH 9.0. Digestion with trypsin or proteinase eliminated the immunosuppressive activity, whereas treatment with neuraminidase, mixed glycosidase, DNase or RNase had no effect, suggesting that the immunosuppressive activity in H69 supernatant is due to a protein factor. This H69-derived immunosuppressive factor was isolated by ion exchange chromatography using a gradient of 0.04 to 0.08 M NaCl solution. Gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the factor to have molecular weights of 98 kD and 102 kD, respectively. These results suggest that SCLC cells produce a potent immunosuppressive factor which may account for the immune deficiency in SCLC patients.
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PMID:Characterization and purification of an immunosuppressive factor produced by a small cell lung cancer cell line. 185 Jul 26

Previously, we showed that in vitro resistance to daunorubicin (DNR) at initial diagnosis was related to a poor long-term clinical outcome in childhood acute lymphoblastic leukemia (ALL), and that cells of relapsed ALL were in vitro more resistant to DNR than cells of untreated ALL. Topoisomerase II (Topo II) is an intracellular target for anthracyclines and epipodophyllotoxins. Decreased levels and/or activity of Topo II have been associated with multidrug resistance in cell lines. We investigated Topo II alpha gene expression in fresh leukemic samples from 19 children with untreated and 14 children with relapsed ALL using a sensitive RNase protection assay. The in vitro cytotoxicity of the Topo II inhibitors DNA and teniposide (VM26) was measured using the MTT assay, and the cell cycle distribution of leukemic samples was analyzed by DNA flow cytometry. Results showed that (1) relapsed ALL samples were more resistant to DNR, but not to VM26 compared to untreated samples; (2) large interpatient variations existed in both Topo II alpha gene expression and in vitro cytotoxicity results; (3) Topo II alpha gene expression was detectable in 29/33 childhood ALL samples with a median expression of 5% the level of a relatively chemosensitive human small cell lung cancer cell line; (4) Topo II alpha gene expression did not differ between untreated and relapsed ALL; (5) Topo II alpha gene expression was positively correlated with the percentage of ALL cells in S- and G2M-phase, but not with the in vitro cytotoxicity of the drugs tested. In conclusion, resistance to DNR in childhood ALL can not be explained by decreased levels of Topo II alpha gene expression, but additional Topo II activity studies in fresh leukemia samples may need further exploration.
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PMID:Topoisomerase II alpha gene expression in childhood acute lymphoblastic leukemia. 756 5

Calcitonin (CT) and calcitonin gene related peptide (CGRP) are derived from preprohormones encoded by three mRNAs (CT, alpha-CGRP and beta-CGRP) from two genes (CALC1 and CALC2) on chromosome 11. Among 16 small cell lung cancer cell lines examined by RNase protection assay, 9 (56%) had detectable CT mRNA, 8 (50%) had alpha-CGRP mRNA, and 13 (81%) had beta-CGRP mRNA. At least one CALC1 transcript (CT or alpha-CGRP) was found in 11 (69%) cell lines with three having only CT mRNA, two having only alpha-CGRP mRNA, and six having both. beta-CGRP mRNA was detected in all of these 11 cell lines expressing a CALC1 transcript. Immunoreactive CT was detected by radioimmunoassay in eight of nine SCLC cell lines expressing CT mRNA, and immunoreactive CGRP was detected in 12 of 13 cell lines expressing a CGRP mRNA. The variety of expression of these three peptides in different cell lines of the same cell type should provide a useful system for further study of the control of expression of these peptides.
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PMID:Small cell lung carcinoma cell lines express mRNA for calcitonin and alpha- and beta-calcitonin gene related peptides. 801 84

To determine the relative contribution of ectopic calcitonin (CT) production versus nonectopic secretion of CT in patients with small cell lung cancer (SCLC), serum and urine immunoreactive CT (iCT) levels of 86 different subjects were measured by radioimmunoassay (RIA) using two polyclonal antisera (Ab3b and Ab4). The subjects included 49 previously untreated patients with SCLC, 17 smokers, and 20 nonsmokers. Serum and urine iCT values were highest in the patients with SCLC, intermediate in the smokers, and lowest in the nonsmokers (p < 0.0003). Sixteen of the 49 patients with SCLC had tumor cell lines available for determination of CT mRNA expression by RNase protection assay (RPA) and iCT production by RIA. CT mRNA was detected in nine of 16 subjects and iCT in eight of 16. The tumor cell lines of seven patients had undetectable CT by both RPA and RIA, and of these, five had elevated urine or serum iCT values compared with those of nonsmokers, and two had levels above all values in the smoker group. Immunohistochemical staining of formalin-fixed, paraffin-embedded tumor samples detected iCT in two of four tumors from patients whose tumor cell lines had CT mRNA by RPA and iCT by RIA, but in none of six whose tumor cell lines had undetectable CT mRNA. Thus, increased iCT values in some patients with SCLC are likely due to sources other than CT production by tumor cells.
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PMID:Calcitonin elevation in small cell lung cancer without ectopic production. 811 80

Small cell lung cancer cell (SCLC) lines, NCI-H82, NCI-H660, and NCI-H1284, and HeLa cells were analyzed for the presence of atrial natriuretic peptide (ANP) receptors. In these SCLC cell lines and HeLa cells, ANP A receptor mRNA was identified by Southern blot analyses of polymerase chain reaction products and RNase protection assays using poly(A)(+)-selected RNA. Saturable binding assays revealed that HeLa cells had 2000 to 5000 high affinity atrial natriuretic peptide receptors per cell with a dissociation constant of 140 pM. In the SCLC cell lines, the binding was saturable but too low to accurately estimate the number of binding sites. After addition of human ANP, radioimmunoassays revealed accumulation of cyclic GMP in SCLC cells as well as HeLa cells in a dose-dependent fashion. The half-maximal stimulation concentration of cyclic GMP accumulation in HeLa and these SCLC cell lines was approximately 2 nM. Tetrazolyl blue assays and tritiated thymidine incorporation did not show any remarkable growth inhibition or growth stimulation of SCLC cell lines after addition of human ANP up to 3.3 microM, more than 1000-fold greater than the half-maximal stimulation concentration of cyclic GMP accumulation. Our results indicate that human SCLC cells express functional ANP receptors but ANP addition produced no detectable change in their growth pattern.
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PMID:Human small cell lung cancer cell lines express functional atrial natriuretic peptide receptors. 839 89

Human cells can become multidrug resistant (MDR) by an increase in the activity of the MDR1 P-glycoprotein or by other, as yet unknown mechanisms, referred to as non-P-glycoprotein mediated MDR (non-Pgp MDR). S. P. C. Cole et al. [Science (Washington DC), 258: 1650-1654, 1992] recently reported that in two cell lines non-Pgp MDR was associated with the overexpression of a new putative membrane transporter gene, MRP. Using an RNase protection assay we have analyzed the expression of MRP in non-Pgp MDR sublines of the human lung cancer cell lines SW-1573 (non-small cell lung cancer) and GLC4 (small cell lung cancer). In all of ten SW-1573 derived lines examined the MRP mRNA level was equal to that in the parental line, whereas MRP was 25-fold overexpressed in a resistant subline of GLC4. We conclude that overexpression of MRP cannot account for all forms of non-Pgp MDR.
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PMID:Analysis of the expression of MRP, the gene for a new putative transmembrane drug transporter, in human multidrug resistant lung cancer cell lines. 846 91

Recombinant human ribonuclease 1 (RNase 1) was chemically linked to recombinant human epidermal growth factor (EGF). The EGF-RNase conjugate showed dose-dependent cytotoxicity for EGF receptor-overexpressing A431 and TE-8 human squamous carcinoma cells with an IC50 of 2 x 10(-7)M and 10(-6)M, respectively, whereas the IC50 of RNase alone was almost 10(-4)M. An unconjugated mixture of EGF and RNase had no greater effect than RNase alone. The conjugate showed no detectable cytotoxicity against EGF receptor-deficient small cell lung cancer cells (H69). Addition of excess EGF in the medium protected A431 cells from the EGF-RNase conjugate cytotoxicity. The cytotoxicity of the EGF-RNase conjugate was positively correlated with the EGF receptor numbers of each cell line. The chimeric toxin composed of only human proteins might be a more useful anti-cancer agent with less immunogenicity than the conventional chimeric toxins.
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PMID:Epidermal growth factor receptor-dependent cytotoxicity for human squamous carcinoma cell lines of a conjugate composed of human EGF and RNase 1. 863 16

The tumoral production of brain natriuretic peptide (BNP) was studied using 9 small cell lung cancer (SCLC) cell lines which were established from patients with small cell lung cancer. BNP cDNA fragment was generated from 20 microg total RNA which was prepared from the human right cardiac atrium by reverse transcription-based polymerase chain reaction. Expression of BNP mRNA was detected in 30 microg total cellular RNA from these cell lines by RNase protection assays in 5 of 9 SCLC cell lines. Radioimmunoassays using 125I-radiolabeled human BNP(1-32) and antihuman BNP(1-32) antibody detected immunoreactivity in cell pellets from SCLC cell lines which had detectable BNP mRNA. BNP immunoreactivity in the cell pellets corresponds with the data from BNP mRNA analyses. We conclude that SCLC cells have detectable BNP mRNA by RNase protection assay and BNP immunoreactivity in the cells.
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PMID:Human small cell lung cancer cells produce brain natriuretic peptide. 994 2

Expression of several molecular determinants of apoptosis was analyzed in 10 untreated small cell (SCLC) and 6 untreated non-small cell (NSCLC) lung carcinoma cell lines. Although SCLC lines were more prone to spontaneous apoptosis compared with NSCLC lines, the former showed higher Bcl-2 expression and a higher Bcl-2/Bax ratio. In order to understand this apparent contradiction, the expression of pro-caspases as well as calpain was analyzed in these cell lines at the protein and mRNA levels. No differences in protein level of pro-caspases-2, -3, -7, and -9 and of calpain were detected between the SCLC and the NSCLC lines, but a striking difference in pro-caspase-8 expression was noted. All 6 NSCLC, but only 2 of the 10 SCLC lines, expressed pro-caspase-8 protein. Further experiments using the RNase protection assay indicated that the lack of pro-caspase-8 expression at the mRNA level was characteristic for SCLC. Using the same experimental approach, we found that SCLC cell lines in addition to pro-caspase-8 were deficient in mRNA expression of pro-caspases-1, -4, and -10, suggesting a different caspase-activating cascade in SCLC compared with NSCLC. This first systematic characterization of pro-caspase expression in lung cancer surprisingly showed that SCLC, which are more prone to undergo spontaneous apoptosis, are deficient in several pro-caspases and have a high Bcl-2/Bax ratio. Thus, the propensity of SCLC cells to undergo apoptosis cannot be explained only by the expression of factors involved in regulation or execution of apoptosis.
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PMID:Differences in expression of pro-caspases in small cell and non-small cell lung carcinoma. 1046 84

The non-pathogenic human adeno-associated virus, AAV, has been shown to sensitize human cancer cells and experimental tumors towards the action of chemotherapeutic agents such as cisplatin. Since chemotherapeutic drugs mainly involve the induction of apoptosis, we investigated whether 1 possible mechanism of AAV-mediated sensitization of human tumor cells may result from an enhancement of cisplatin-induced apoptosis. In HeLa and A549 cells, infection with AAV type 2 (AAV-2) increased cisplatin-induced DNA fragmentation but had no cytotoxic effect by itself. This enhanced apoptosis appeared to be mediated at least in part by a component of the viral capsid since empty or UV-inactivated AAV-2 particles were also able to boost cisplatin-induced DNA fragmentation. Interestingly, these effects were not observed after infection with AAV type 5 (AAV-5) or the autonomous parvovirus, H-1. AAV-2-mediated enhancement of apoptosis was not associated with a modification of the expression of CD95 ligand, CD95 receptor or other death receptors, as shown by RT-PCR and RNase protection assay. In contrast, using the mitochondrial fluorescent dye, JC-1 in flow cytometry, AAV-2 infection was found to further reduce the mitochondrial transmembrane potential after treatment with cisplatin in a caspase-independent manner, suggesting that increase of apoptosis by AAV-2 occurred at the mitochondrial level. In contrast, in cells of the small cell lung cancer line, P693, an enhancement of cisplatin-induced DNA fragmentation was not observed after infection with AAV-2. In these cells, sensitization to cisplatin-toxicity was associated with cell cycle arrest in G2/M. The data indicate that in the absence of viral gene expression, AAV-2-mediated sensitization to cisplatin involves multiple cellular pathways promoting cell death signals in a cell type-dependent manner. The results further support that AAV-2 particles may be appropriate adjuvants for improving cancer chemotherapy and may also have consequences regarding AAV-2-based vectors for gene therapy.
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PMID:Enhancement of cisplatin-induced apoptosis by infection with adeno-associated virus type 2. 1180 2


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