Specific inhibition of oncogene expression in vitro and in vivo by antisense oligonucleotides.
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Animals↗
Biomedical subjects
A Rosolen
Publications and source records attributed to A Rosolen.
Multichain structure of the IFN-alpha receptor on hematopoietic cells.
The structure of IFN-alpha receptor was studied by 1) developing antibodies against the receptor, and 2) screening a number of cell lines by affinity cross-linking to identify cells that express different IFN-alpha 2 receptor structures. We report that two different patterns of IFN-alpha 2 receptor are observed in human cells of hematopoietic origin. The predominant form of the IFN-alpha receptor is a multichain structure in which IFN-alpha 2 forms complexes of 110 and 130 kDa (alpha-subunit). A high Mr complex of 210 kDa results from the association of alpha-subunit and other receptor components. In contrast, another form of the receptor has been identified in the IFN-alpha-resistant U-937 cell line and in some cases of acute leukemia. This form of the IFN-alpha receptor is characterized by the presence of the alpha- subunit, and the absence of the 110- and 210-kDa bands. Also a novel 180-kDa complex and a more prominent 75-kDa band are observed. Functional studies performed in U-937 cells showed that this cell line is not only partially resistant to the antiproliferative and antiviral effects of IFN-alpha, but also fails to down-regulate the alpha-subunit of the IFN-alpha receptor upon IFN-alpha binding.
Cell Line↗
Antisense inhibition of gene expression: a tool for studying the role of NMYC in the growth and differentiation of neuroectoderm-derived cells.
To understand the role of individual genes in regulating biological processes, one must be able to interfere specifically with either their expression or function. While monoclonal antibodies have proven very useful in studying cell surface proteins, the specific inhibition of intracellular proteins in viable cells is a much more difficult problem. The goal of antisense technology is to develop small oligonucleotides, plasmids, or retroviral vectors that can be introduced easily into viable cells in order to inhibit gene products specifically. In this report, we will describe our use of antisense DNA and RNA to study the role of the NMYC proto-oncogene in neuroectodermal cell growth and differentiation.
Animals↗
Antisense inhibition of oncogene expression.
To understand the role of individual genes in regulating biological processes, one must be able to interfere specifically with either their expression or function. While monoclonal antibodies have proven very useful in studying cell surface proteins, the specific inhibition of intracellular proteins in viable cells is a much more difficult problem. The goal of antisense technology is to develop small oligonucleotides, plasmids, or retroviral vectors which can be readily introduced into living cells in order to inhibit specific gene expression. In this review, we briefly describe the principles of antisense usage, including problems of cellular uptake and intracellular distribution, mechanism of antisense action, and the properties of various oligonucleotide derivatives. In addition we present several examples of the biological effects of antisense administration used to study the role of specific genes in the regulation of cell growth and differentiation.
Animals↗
A phase I study of interleukin-2 in children with cancer.
Recombinant interleukin-2 (IL-2) produces clinical responses in approximately 20% of adult patients with renal cell carcinoma and melanoma, with both high-dose bolus and continuous infusion regimens. Because of the lower toxicity of continuous infusion, we elected to investigate in a Phase I trial a 5-day continuous infusion repeated for three weeks in children with malignancies refractory to standard therapy. Nineteen children with solid tumors and eight children with hematologic malignancies were entered into the study. The maximum tolerated dose was 3 x 10(6) U/m2/day, with dose-limiting toxicities occurring in five of seven patients treated at the 5 x 10(6) U/m2/day dose level. Dose-limiting toxicities included hypotension, hyperbilirubinemia, thrombocytopenia, pulmonary/pleural effusion, and nephrotoxicity. Serum IL-2 levels were detectable at the higher dose levels and were comparable to those observed in adult patients. Hematologic changes at the higher dose levels included rebound lymphocytosis occurring within 48 h of discontinuation of IL-2, eosinophilia, and decreased platelet counts. No objective responses to therapy were seen. We have identified a dose and schedule of administration for IL-2 in pediatric patients that can be given without intensive care unit support. Pediatric Phase II trials examining the anti-tumor activity of IL-2 given by this schedule are in progress.
Adolescent↗
In vivo modulation of N-myc expression by continuous perfusion with an antisense oligonucleotide.
In this study we investigated the in vivo efficacy of continuous subcutaneous perfusion of unmodified phosphodiester oligodeoxynucleotides. The in vitro sequelae of antisense inhibition of the target gene, N-myc, have been documented and include moderate growth inhibition without effects on myc expression, loss of secretogranin I expression, and morphologic alterations. We chose to use N-myc as a model target to determine if antisense effects observed in vitro can be reproduced in vivo. N-myc-expressing human neuroectodermal tumors were grown as subcutaneous xenografts in athymic mice. Antisense and sense oligodeoxynucleotides directed against N-myc were delivered to the vicinity of the tumor by a subcutaneously implanted microosmotic pump. Antisense treatment led to loss of N-myc protein from the tumor, as well as to the loss of the neuroendocrine differentiation marker protein secretogranin I. Myc protein expression remained unaffected. Mean tumor mass was reduced by 50% in antisense-treated animals, and antisense-treated tumors morphologically resembled antisense-transfected in vitro cell cultures. These results demonstrate that regional, in vivo perfusion of an unmodified oligonucleotide specifically downregulates gene expression in human tumor xenografts with concomitant effects on tumor phenotype and growth rate that correlate well with in vitro observations.
Base Sequence↗
Episome-generated N-myc antisense RNA restricts the differentiation potential of primitive neuroectodermal cell lines.
Neuroectodermal tumors of childhood provide a unique opportunity to examine the role of genes potentially regulating neuronal growth and differentiation because many cell lines derived from these tumors are composed of at least two distinct morphologic cell types. These types display variant phenotypic characteristics and spontaneously interconvert, or transdifferentiate, in vitro. The factors that regulate transdifferentiation are unknown. Application of antisense approaches to the transdifferentiation process has allowed us to explore the precise role that N-myc may play in regulating developing systems. We now report construction of an episomally replicating expression vector designed to generate RNA antisense to part of the human N-myc gene. Such a vector is able to specifically inhibit N-myc expression in cell lines carrying both normal and amplified N-myc alleles. Inhibition of N-myc expression blocks transdifferentiation in these lines, with accumulation of cells of an intermediate phenotype. A concomitant decrease in growth rate but not loss of tumorigenicity was observed in the N-myc nonamplified cell line CHP-100. Vector-generated antisense RNA should allow identification of genes specifically regulated by the proto-oncogene N-myc.
Animals↗
Antisense inhibition of N-myc reduces cell growth but does not affect c-myc expression in the neuroepithelioma cell line CHP100.
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Base Sequence↗
Antisense suppression of N-myc expression inhibits the transdifferentiation of neuroectoderm tumor cell lines.
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Animals↗
Antisense inhibition of single copy N-myc expression results in decreased cell growth without reduction of c-myc protein in a neuroepithelioma cell line.
The N-myc gene is transiently expressed during normal embryonic development and abnormally expressed in several tumors of neuroendocrine origin. Little is known of the function of the N-myc gene product in either normal or neoplastic tissue. We utilized synthetic antisense oligodeoxynucleotides to specifically inhibit N-myc gene expression in the neuroepithelioma cell line CHP100. These cells contain single copy N-myc alleles but overexpress c-myc. N-myc antisense oligomer treatment was found to be growth inhibitory without affecting levels of c-myc protein. N-myc antisense oligomer-treated cells also lost the characteristic cellular heterogeneity displayed by CHP100 in vitro.
Cell Division↗
Putative gamma-subunit of the IL-2 receptor is detected in low, intermediate, and high affinity IL-2 receptor-bearing cells.
Three forms of the IL-2R have been reported: low, intermediate, and high affinity. Each form correlates with the expression of two different chains: p55 (alpha-subunit) and p75 (beta-subunit). We report here a putative new subunit of the IL-2R, termed p95-110 or gamma-subunit. This new subunit has a molecular mass of 95 to 110 kDa and is expressed in low, intermediate, and high affinity IL-2R-bearing cells. We propose that p95-110 is the partner of p75 in the formation of intermediate affinity IL-2R, inasmuch as neither p75 nor p95-110 alone can bind IL-2.
Cell Adhesion Molecules↗
Expression of low-, intermediate-, and high-affinity IL-2 receptors on B cell lines derived from patients with undifferentiated lymphoma of Burkitt's and non-Burkitt's types.
IL-2 receptors on T cells exist in at least three forms which differ in their ligand-binding affinity. The low-affinity IL-2 receptor (IL-2R) consists of the 55-kDa Tac protein (p55 alpha), the intermediate-affinity site corresponds to the 70-kDa molecule (p70 beta), and the high-affinity IL-2R consists of a noncovalent heterodimeric structure involving both p55 alpha and p70 beta. We studied 24 B cell lines (8 EBV-negative and 16 EBV-positive) for IL-2R expression in the presence or absence of the tumor promoter, teleocidin. 125I-IL-2 radioreceptor binding assays and crosslinking studies demonstrated the sole expression of p55 alpha in EBV-negative cell lines only, whereas p55 alpha present in EBV-positive cell lines was always associated with p70 beta to construct high-affinity IL-2R. p70 beta was not detected in any of the EBV-negative cell lines, but was expressed on most of the EBV-positive cell lines (13 of 16). Our data also indicate that the expression of p55 alpha and p70 beta by radiolabeling correlates with their expression in flow cytometry, and that a large excess of p55 alpha is required to construct high-affinity IL-2R. Coexpression of p55 alpha and p70 beta on human B cells contributed to constructing high-affinity IL-2R hybrid complex as shown by (i) rapid association rate contributed by p55 alpha and slow dissociation rate by p70 beta; (ii) teleocidin's ability to induce p55 alpha on cell lines which express p70 beta only, resulting in appearance of high-affinity IL-2R; (iii) blocking p55 alpha by anti-Tac mAb in cell lines which constitutively express high-affinity IL-2R eliminated both high- and low-affinity components. The existence of low, intermediate, and high IL-2R on human B cells bears important future implications for understanding the mechanism of IL-2 signaling and the role of IL-2 in B cell activation, proliferation, and differentiation.
B-Lymphocytes↗
Expression of interleukin-2 receptor beta subunit in hematopoietic malignancies.
The expression of the interleukin-2 (IL-2) receptor was studied in neoplastic cells derived from acute leukemias, T-cell lymphoblastic lymphomas, peripheral T-cell lymphomas, chronic lymphocytic leukemias, well-differentiated lymphocytic lymphomas, and established cell lines by both flow cytometric analysis and sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) after affinity crosslinking of radiolabeled IL-2. Cells from most acute leukemias (19 of 22), irrespective of their subtype (T, common or nonlymphoid leukemias), as well as T-cell lymphoblastic lymphomas and peripheral T-cell lymphomas expressed only the p70-75 beta subunit of the IL-2 receptor. Cells from the more mature B-cell neoplasms, chronic lymphocytic leukemia, and well-differentiated lymphocytic lymphoma, expressed predominantly alpha beta IL-2 receptors (11 of 14). In contrast to these results, most cell lines established from hematopoietic malignancies do not express either chain of the IL-2 receptor. Further studies are necessary to determine the exact function of the IL-2R p70-75 beta subunit in immature hematopoietic cells, but its wide distribution throughout the hematopoietic system suggests that IL-2 may play a role in the early stages of hematopoiesis.
Cell Line↗
Stimulation of the beta-subunit of the IL-2 receptor induces MHC-unrestricted cytotoxicity in T acute lymphoblastic leukemia cells and normal thymocytes.
Recently, several laboratories have identified a novel protein(s) of 70,000 to 75,000 Da (IL-2R beta-subunit) that, when expressed with the p55 Tac protein (alpha-subunit), imparts high affinity IL-2 binding. Expression of the beta-subunit mediates acquisition of MHC-unrestricted cytotoxicity in large granular lymphocytes. We report that thymocytes and T acute lymphoblastic leukemia cells express the beta-subunit of the IL-2R in the absence of detectable alpha-subunit expression and that IL-2 induces acquisition of MHC-unrestricted cytotoxic activity in these cells through stimulation of the beta-subunit.
Child↗
Factor VIII/von Willebrand factor abnormalities during L-asparaginase treatment in patients with acute lymphoblastic leukemia.
Factor VIII/von Willebrand factor (VIII/vWf) related properties were studied in 10 patients affected by acute lymphoblastic leukemia during L-asparaginase-vincristine-prednisone treatment. These properties remained within the normal range during the period of observation without any difference from the basal values. On the contrary, VIII:C activity was already increased before medication and showed gradual additional elevation during the observation period, reaching a peak 1 week after discontinuation of L-asparaginase administration. Crossed immunoelectrophoresis of vWf, performed weekly in 2 patients during the period of medication, demonstrated a normal pattern before the beginning of treatment, but an apparently faster migrating peak during L-asparaginase therapy, suggesting a qualitative abnormality of vWf. No abnormal bleeding tendency was found in any of the patients.
Adolescent↗
The beta subunit of the interleukin-2 receptor mediates interleukin-2 induction of anti-CD3 redirected cytotoxic capability in large granular lymphocytes.
The interleukin 2 (IL 2) receptor was studied in three cases of large granular lymphocyte (LGL) lymphocytosis. All cases were nonreactive with anti-Tac monoclonal antibody (MoAb; recognizing the p55 alpha subunit of the IL 2 receptor). Sodium dodecyl sulfate (SDS)/polyacrylamide gel electrophoretic analysis (PAGE) of cells to which radio-labeled rIL 2 had been chemically crosslinked revealed uniform expression of the p70/75 beta subunit of the IL 2 receptor in the absence of the alpha subunit. Stimulation of this receptor with 2 nmol/L rIL 2 for five days led to acquisition of anti-CD3 redirected cytotoxicity. This was accompanied by a fivefold to tenfold elevation in the activity of intracellular N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl esterase, an LGL granule marker enzyme. These effects of IL 2 did not require induction of the Tac peptide.
Antigens, Surface↗
Failure of L-asparaginase to decrease protein C--A possible rebound phenomenon.
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Adolescent↗
Clotting complications of L-asparaginase therapy in children with ALL.
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Afibrinogenemia↗