Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P14784 (IL-2 receptor)
 3,849 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has previously been demonstrated that retinoic acid (RA) enhances the blastogenic responses of human thymocytes. We have now delineated the cellular mechanism of this activity. When RA was added to resting thymocyte cultures in the presence of recombinant interleukin-2 (rIL-2), blastogenesis was increased two- to fourfold. By assessing the proportion of cells that became Tac-positive and showed DNA synthesis early in the activation process, we determined that the augmentation by RA was not caused by an increased recruitment of resting cells that are activated to undergo blast transformation. Instead, RA markedly potentiated the growth rate of long-term rIL-2-dependent thymocyte blasts and, correspondingly, increased the Tac expression on these proliferating cells. Thus, RA enhancement of thymocyte responses appears to be mediated by an increase in IL-2-receptor expression on thymocyte blasts, resulting in augmented IL-2-dependent growth. This effect is independent of the original activating stimulus since enhancement of thymocyte responses to phytohemagglutinin (PHA) was also shown to be caused solely by increased proliferation of IL-2-dependent blast growth. In contrast to these effects on thymocytes, peripheral blood lymphocyte (PBL) proliferative responses were unaffected by RA treatment and, correspondingly, RA affected neither IL-2 receptor expression on PBL blasts nor the growth of these cells. Taken together, the results of this study suggest that RA can modulate IL-2-dependent immune responses, in part, by upregulating the expression of IL-2 receptors on proliferating T lymphoblasts generated from cells at restricted stages of development.
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PMID:Retinoic acid upregulates interleukin-2 receptors on activated human thymocytes. 313 32

Since all-trans retinoic acid (ATRA) and granulocyte colony-stimulating factor (G-CSF) not only enhance proliferation and differentiation of normal myeloid cells but also synergistically promote the differentiation of myeloid leukemic blast cells in vitro, we have started a pilot study of combined treatment with ATRA and G-CSF in patients with myelodysplastic syndrome, to analyze the effect of these drugs on hematopoietic differentiation. ATRA was given at 45 mg/m2/day p.o. from week 1-12 and G-CSF at 5 micrograms/kg/day s.c. from week 5-12 with dose modifications according to the absolute neutrophil counts (ANC). A total of 15 patients, predominantly with refractory anemia, were treated. During initial ATRA therapy, a bilineage response with increases of both ANC and platelet counts occurred in three patients. During combined ATRA/G-CSF therapy, ANC increased in all patients, and platelets increased in three out of 14 evaluable patients. An increase in hemoglobin concentration and a decrease in transfusion requirements occurred in one patient each. In the bone marrow, the myeloid-to-erythroid ratio increased during ATRA treatment and remained increased during concomitant G-CSF administration, while the maturation index of myeloid cells increased only in response to ATRA therapy, but returned to baseline during ATRA/G-CSF treatment. Cytogenetic analysis demonstrated persistence of the abnormal clones in all patients. The number of circulating progenitor cells CFU-GM increased in all patients studied. Serum concentrations of the soluble TNF receptor and IL-2 receptor both increased, while TNF-alpha--already elevated prior to therapy--and soluble ICAM-1 concentrations did not significantly change. Adverse effects included dermatitis and cheilosis in most patients, and a drop in platelet counts related to G-CSF in one patient. The pilot study demonstrates that the combination treatment with ATRA/G-CSF is well tolerated, leading to normalization of ANC in most, and improvement of platelets and red blood cells in a subgroup of patients.
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PMID:Effect of combination therapy with all-trans-retinoic acid and recombinant human granulocyte colony-stimulating factor in patients with myelodysplastic syndromes. 751 Mar 54

It was previously demonstrated that retinoic acid (RA) can enhance the functional responses of human T lymphocytes by increasing surface IL-2R alpha chain protein expression on proliferating T blasts, resulting in augmented IL-2-dependent growth. In the present study, we used IL-2-maintained lymphoblasts generated from human thymocytes to show that RA enhancement of IL-2R alpha is accompanied by an increase in steady-state levels of IL-2R alpha mRNA. This increase occurred within 1 hr after the addition of RA to the culture and was inhibited by the presence of the protein synthesis inhibitor cycloheximide. RA did not alter the stability of either IL-2R alpha on the cell surface or IL-2R alpha mRNA, suggesting regulation by RA at the level of transcription. This contention was supported by the demonstrated ability of RA to activate the IL-2R alpha promoter in a chloramphenicol acetyltransferase plasmid construct that was transfected into the blast cells. In addition to inducing IL-2R alpha expression, RA also increased the surface expression and mRNA levels of IL-2R beta, the 75-kDa component of the IL-2 receptor that mediates IL-2 signal transduction. These new findings showing regulation by RA of both IL-2R alpha and IL-2R beta suggest multiple pathways by which this retinoid can modulate functional IL-2 receptors.
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PMID:Upregulation by retinoic acid of interleukin-2-receptor mRNA in human T lymphocytes. 767 84

Retinoids have anti-tumor activity in several malignant and premalignant conditions. Since Kaposi's sarcoma is regulated by steroid hormones both in vivo and in vitro, we hypothesized that retinoids may have anti-tumor effects in AIDS-related Kaposi's sarcoma. Thus, 27 patients with mucocutaneous, non-visceral AIDS-related Kaposi's sarcoma were treated with all-trans retinoic acid (tRA). Poor tolerance was observed at the initial starting dose of 150 mg/m2, and thus subsequent patients were treated using a weekly dose escalation, starting with 45 mg/m2 (given daily, in subdivided doses), to the target dose of 150 mg/m2 (given daily in three subdivided doses). Nearly half (46%) of the patients had extensive mucocutaneous disease with over 25 lesions. No patient had received prior cytotoxic chemotherapy. Ten patients had CD4 lymphocytes of 200/mm3 or greater (strata I); and 17 had under 200/mm3 CD4 lymphocytes (strata II). The median of the average daily tRA dose administered was 150 mg (90 mg/m2; there was no significant difference in the dose tolerance between the two strata). Adverse effects consisted of transient mild to moderate headaches in 65% of patients, mild to moderate skin dryness and cheilitis in 61%, and nausea and vomiting in 31%. Hematologic toxicities included hypertriglyceridemia in 62%, anemia in 23%, and neutropenia in 23%. Partial response to therapy was observed in 4/24 (17%) evaluable patients, occurring after 12, 20, 24, and 28 weeks of therapy, and lasting 4-24 weeks. Three responders had baseline CD4 lymphocyte counts < 200/mm3. Three additional patients experienced reduction in measured indicator lesions of greater than 25% but less than 50%, and seven patients experienced disease stabilization of 16 weeks or greater. In evaluable patients, the median time to disease progression was 22 weeks and the overall median survival in all patients was 27.3 months. No significant changes in CD4 lymphocyte counts, p24 antigen, and beta 2 microglobulin were observed over time. However, a statistically significant increase was observed in soluble IL-2 receptor levels while on tRA (p = 0.037). We conclude that tRA has activity in patients with mucocutaneous AIDS-related Kaposi's sarcoma with acceptable toxicity. tRA has immunological effects without upregulation of HIV parameters. Additional studies in combinations or with more active retinoids are warranted.
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PMID:All-trans retinoic acid for the treatment of AIDS-related Kaposi's sarcoma: results of a pilot phase II study. 780 21

Differentiation induction therapy is being tested in myelodysplastic syndromes to ameliorate maturation defects and to restore normal hematopoietic function. To this end, 17 patients (eight with refractory anemia, two with refractory anemia and ring sideroblasts, and seven with refractory anemia and excess of blast cells) were treated with a combination of all-trans-retinoic acid (ATRA), granulocyte colony-stimulating factor (G-CSF), erythropoietin (EPO), and alpha-tocopherol for durations of 8-16 weeks. Absolute neutrophil counts increased in all patients; platelet counts increased in five patients with discontinuation of transfusion needs in two of four transfusion-dependent patients. Stimulation of erythropoiesis was seen in eight patients with an increase in hemoglobin concentration in three, a discontinuation of transfusion requirements in another three, and a significant increase in reticulocyte counts as the only parameter in two patients. Clinically important multilineage responses with increases of hemoglobin levels or discontinuation of transfusion needs were thus seen in six patients (35.3%) with three patients having a trilineage response. Serum erythropoietin concentrations did not differ significantly between responders and nonresponders, but the erythroid response was accompanied by a rise in the serum transferrin receptor levels. In the bone marrow, the myeloid-to-erythroid ratio and the maturation index of myeloid cells increased during therapy, while the percentage of blast cells did not change. Cytogenetic analysis demonstrated the persistence of the abnormal clones. Prior to therapy, nonresponders had a significantly higher serum TNF level than responders. Serum concentrations of TNF-alpha and soluble TNF-alpha receptor significantly increased during therapy, but mainly in the patients without an erythroid and platelet response. Soluble IL-2 receptor and soluble ICAM-1 concentrations both increased. This pilot study demonstrates that treatment with ATRA/G-CSF/EPO/tocopherol is well tolerated, leading to normalization of neutrophil counts in most, and to improvement of platelets and red blood cells in a significant subgroup of patients.
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PMID:Improved multilineage response of hematopoiesis in patients with myelodysplastic syndromes to a combination therapy with all-trans-retinoic acid, granulocyte colony-stimulating factor, erythropoietin and alpha-tocopherol. 862 78

At the end of an immune response, most activated T cells spontaneously undergo programmed cell death (apoptosis). In the present study we show that all-trans retinoic acid (atRA), a major vitamin A metabolite, can inhibit the spontaneous apoptosis of activated human T lymphocytes in vitro. Isolated peripheral blood T lymphocytes were activated by 12-O-tetradecanoyl phorbol 13-acetate and cultured for up to 11 days without any further stimuli. With time, a gradual increase in cell death was observed. This spontaneous death of activated T cells was apoptotic, as demonstrated by cell shrinkage, DNA fragmentation and depolarization of the mitochondrial membrane. In the presence of physiological concentrations of atRA, the percentage of T cells exhibiting these apoptotic features was significantly reduced. After 5 days of stimulation, the percentage of TUNEL+ T cells decreased from 28 to 12% in the presence of atRA. The anti-apoptotic effect of atRA was mimicked by the retinoic acid receptor (RAR)-selective agonists 4-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid and AM-580, and totally abrogated by the RAR-selective antagonist Ro 41-5253. Cytokines of the IL-2 family have been shown to improve the survival of activated T cells. Strikingly, we found that the ability of atRA to inhibit apoptosis was significantly correlated with its ability to increase the production of IL-2. Furthermore, a blocking anti-IL-2 receptor antibody completely abrogated the anti-apoptotic effect of atRA. Together, these results suggest that retinoic acid inhibits spontaneous apoptosis of activated T lymphocytes through a RAR-dependent increase in IL-2 production.
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PMID:Survival of activated human T lymphocytes is promoted by retinoic acid via induction of IL-2. 1497 18

Hypoxia induces survival signals in hepatocellular carcinoma (HCC). Hypoxia and retinoic acid (RA) may also induce interleukin-2 (IL-2) receptor expression, and thus we evaluated if RA and IL-2 receptor-targeted therapy are indicated in hypoxic HCCs. RA induced IL-2 receptor expression (R alpha, R beta, R gamma) in HCC cells, whereas hypoxia specifically induced IL-2 R gamma expression. IL-2 stimulated hypoxic HCC cell growth via p42/44 MAPK activation. Combination of denileukin diftitox and RA significantly suppressed hypoxic HCC cell growth compared to single agent-treated or normoxic cells. Therefore, denileukin diftitox and RA may be therapeutically implicated in infiltrative HCCs which are exposed to hypoxic environments.
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PMID:Enhanced interleukin-2 diphtheria toxin conjugate-induced growth suppression in retinoic acid-treated hypoxic hepatocellular carcinoma cells. 1898 61