Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023467 (acute myeloid leukemia)
 35,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The HL-60 cell line, derived from a patient with acute promyelocytic leukemia, proliferates continuously in suspension culture and consists predominantly (greater than 90%) of promyelocytes. These cells can be induced to differentiate to morphologically and functionally mature granulocytes by incubation with a wide variety of compounds, including butyrate and hypoxanthine and polar planar compounds such as dimethyl sulfoxide and hexamethylene bisacetamide. We have now found that retinoic acid (all-trans-retinoic acid) induces differentiation (as measured morphologically and by the ability to reduce nitroblue tetrazolium) of HL-60 at concentrations as low as 1 nM. Maximal differentiation (approximately 90%) occurs at 1 micro M, a concentration 1/500th to 1/160,000th the concentrations of butyrate (0.5 mM) and dimethyl sulfoxide (160 mM) that promote a similar increase in differentiation. Continuous exposure to retinoic acid is necessary for optimal differentiation, with the percentage of mature cells in the culture directly related to the length of time of exposure to retinoic acid. Retinoic acid and 13-cis-retinoic acid are equally effective in inducing differentiation of HL-60. Retinol (vitamin A), retinal, and retinyl acetate are approximately 1/1000th less potent. This study suggests that retinoids could provide a therapeutic tool in the treatment of acute myeloid leukemia, a disease that has been looked upon as primarily involving a block in myeloid differentiation, and indicates that retinoids, in addition to their well-characterized involvement in epithelial cell differentiation, may also be involved in the differentiation of certain hematopoietic cells.
 ...
PMID:Induction of differentiation of the human promyelocytic leukemia cell line (HL-60) by retinoic acid. 693 Jun 76

Retinoic acid and hydrocortisone (HC) have been shown to regulate the drug sensitivity of the blast cells of acute myeloblastic leukemia (AML). We asked if the proto-oncogene bcl-2 played a role in this regulation. As target cells we used the continuous lines, OCI/AML-1, OCI/AML-2 or OCI/AML-5; expression of bcl-2 can be detected by Northern analysis of RNA from OCI/AML-2 or OCI/AML-5 cells; bcl-2 expression can be found in OCI/AML-1 cells only by using RT-PCR. Exposure of OCI/AML-2 or OCI/AML-5 cells to retinoic acid (all-trans retinoic acid, ATRA) led to a down-regulation of bcl-2 expression that was first seen after 2 h of exposure and was complete after a day. The down-regulation could be prevented by exposing the cells to ara-C either before or after ATRA; decrease in bcl-2 protein was moderate and only obvious after 36 h of ATRA treatment. Nuclear run-on experiments provided evidence that bcl-2 down-regulation was occurring at transcriptional and post-translational levels. Since bcl-2 is considered to have anti-oxidant activity, we tested the sensitivity of the three cell lines to H2O2; we found that OCI/AML-1, the line with very low bcl-2 expression, was a 100-fold more H2O2-sensitive than OCI/AML-2 or OCI/AML-5, where bcl-2 expression can be detected readily. We then asked if H2O2 sensitivity could be regulated. We found that exposure of cells to HC before H2O2 was protective while ATRA after peroxide treatment increased killing; this is the same pattern of regulation observed when AML blasts are exposed to HC before, or ATRA after ara-C. Finally, we asked whether N-acetylcysteine (NAC), a known radical scavenger would protect cells against ara-C killing. Significant protection was observed when NAC was given before drug, but not if given after drug. NAC protection against ara-C killing was seen for OCI/AML-1 and 2 cells, but not for OCI/AML-5 cells. We interpret the results as follows: ara-C kills cells in two ways: first, directly, by incorporation into DNA and chain termination; second, indirectly, by inducing the production of toxic radicals. Bcl-2 reduces the oxidant activity of such radicals, and is protective. ATRA regulates ara-C toxicity by its action on bcl-2. Left unexplained are the action of HC, which does not affect bcl-2 expression and the mechanism by which ara-C prevents down-regulation of bcl-2 by ATRA.
 ...
PMID:Mechanism of cytosine arabinoside toxicity to the blast cells of acute myeloblastic leukemia: involvement of free radicals. 776 41

Retinoic acid (RA) is an interesting agent which has been shown to induce differentiation and complete remission in patients with acute promyelocytic leukemia. 1,25-(OH)2-delta 16-23-yne-cholecalciferol (16-23-D3) and 1,25-(OH)2-23-yne-cholecalciferol (23-D3) are vitamin D3 analogs capable of inducing differentiation of myeloid leukemic cells with little effect on either calcium absorption or mobilization. Using HL-60 myeloid leukemic cells as in vitro model for human acute myeloid leukemia we observed an additive to synergistic interaction between RA and 16-23-D3 or 23-D3 with respect to the inhibition of cell growth and DNA synthesis, the induction of differentiation and the loss of cell clonogenicity. In addition, we observed that RA and 16-23-D3 interact additively with respect to the reduction of c-myc mRNA expression. These results suggest that Ra used in combination with 16-23-D3 or 23-D3 may be an interesting chemotherapeutic regimen to evaluate in patients with acute myeloid leukemia.
 ...
PMID:Interaction of retinoic acid and vitamin D3 analogs on HL-60 myeloid leukemic cells. 839 95

Retinoic acid exhibits effects on the proliferation and differentiation of many hematopoietic cells. Cellular responsiveness to retinoic acid (RA) is conferred through two distinct classes of nuclear receptors, the RA receptors (RARs) and the retinoid X receptors (RXRs). The RARs bind to both 9-cis- and all-trans-RAs, but 9-cis-RA alone directly binds and activates RXR. This suggested that 9-cis-RA could have expanded hematopoietic activities as compared with all-trans-RA. We compared the abilities of 9-cis- and all-trans-RAs to induce differentiation and inhibit proliferation of three acute myelogenous leukemia (AML) cell lines and fresh leukemic cells from 28 patients and found that: (1) 9-cis-RA in general was more potent than all-trans-RA in suppressing the clonal growth of two AML cell lines and 17 AML samples from patients, including four from individuals with acute promyelocytic leukemia (APL). Eleven leukemic samples, including three from patients with chronic myelogenous or chronic myelomonocytic leukemia, were relatively refractory to both retinoids. (2) The range of activities of both retinoids was similar except that the clonal growth of samples from three AML patients were inhibited by 9-cis-RA, but not by all-trans-RA. (3) Both retinoids inhibited the clonal proliferation of leukemia cells without necessarily inducing their differentiation; in fact, the only fresh AML cells that were able to undergo differentiation were from patients with APL and one individual with M2 AML. (4) Both retinoids enhanced myeloid and erythroid clonal growth from normal individuals, and 9-cis-RA showed slightly more stimulation of the myeloid clonal growth than did the all-trans-RA. Our study suggests that 9-cis-RA is worthy of further study for the treatment of selected individuals with AML.
 ...
PMID:9-cis-retinoic acid: effects on normal and leukemic hematopoiesis in vitro. 842 82

Retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (D3) are well known for inducing differentiation in many leukemic cell lines. The nuclear signalling pathways of RA and D3 are mediated through their cognate receptors, the retinoic acid receptor (RAR) and vitamin D3 receptor (VDR), respectively. Retinoid X receptor (RXR) is an auxiliary factor that forms a heterodimer with RAR and VDR, enabling their efficient transcriptional activation. 9-cis RA, a high-affinity ligand for RXR, greatly enhanced D3-induced CD14 expression in U937 cells, while RA alone did not induce CD14 expression. 9-cis RA also resulted in morphological changes of U937 cells to macrophage-like cells when combined with D3, while RA alone resulted in granulocyte-like cells. RA and D3 together enhanced c-fms expression, phagocytic activity, and acted synergistically to promote nitroblue tetrazolium reduction activity and inhibit proliferation. Northern analysis showed that U937 cells constitutively expressed RAR-alpha, VDR and RXR-alpha mRNAs. RA or D3 alone or in combination did not affect RAR-alpha and VDR expression, while 9-cis RA and 9-cis RA plus all-trans RA significantly reduced RXR-alpha expression. Interestingly, D3 could restore the down-regulation of RXR-alpha mRNA by 9-cis RA. These findings suggest that there is crossover of the nuclear signalling pathways of RA and D3. This may have clinical implications in that RA and D3 may be used in combination for differentiation-inducing therapy in acute myelogenous leukemia and myelodysplastic syndrome.
 ...
PMID:All-trans and 9-cis retinoic acid enhance 1,25-dihydroxyvitamin D3-induced monocytic differentiation of U937 cells. 911 35

Retinoic acid has the ability to induce differentiation in some myeloid leukaemia cell lines and has been used to induce remission in acute promyelocytic leukaemia patients. We have analysed changes in gene expression, by differential display, in HL60 cells exposed to all-trans retinoic acid (ATRA) for only 1 h. Only about 0.4% of the genes examined by this technique showed changes in expression level, and all four of the gene fragments identified were downregulated during the short 1 h exposure. Two of the fragments were novel, a third was MYC and the fourth was the FUS proto-oncogene. Northern analysis showed that FUS was downregulated within 1 h only during induced neutrophil differentiation but not at all during induced monocyte differentiation. Unlike the sensitive cell lines, ATRA-resistant cell lines did not show a downregulation of FUS over a 24 h period of exposure to ATRA. Using a semiquantitative PCR analysis, no difference in FUS levels was observed between ATRA-sensitive and -resistant cell lines. A similar analysis was carried out on primary acute myeloid leukaemia (AML), peripheral stem cell harvests (PBSC) and cord blood samples. The PBSC and cord blood samples had FUS levels that were similar or generally less than the cell lines. However, much higher levels were seen in 63% of the AML samples examined. The data presented are consistent with previous reports for a role for FUS in the promotion and maintenance of cellular proliferation.
 ...
PMID:High FUS/TLS expression in acute myeloid leukaemia samples. 1069 62

Murine models of human neoplasms are being used to expand our understanding of pathogenesis and to develop improved cancer therapies. MRP8-PMLRARalpha transgenic mice represent one model of human acute promyelocytic leukemia (APL). These mice develop leukemias that mirror characteristic features of human APL including responsiveness to retinoic acid and arsenic. This model is proving its value in elucidating mechanisms by which PMLRARalpha contributes to leukemia, identifying genetic changes that cooperate to cause leukemia, and investigating new molecular targets for leukemia therapy. These studies suggest that acute myeloid leukemias (AMLs) such as APL result from genetic changes that combine to both impair differentiation and allow immature cells to survive and proliferate outside of a normal microenvironment. Retinoic acid targets the central molecular lesion in human APL and has greatly improved survival. Molecularly targeted therapies that either restore maturation or abrogate growth autonomy represent a hope for improving survival of patients with other subtypes of AML.
 ...
PMID:Acute promyelocytic leukemia: a view from a mouse. 1135 54

Retinoic acid (RA) has important effects on cell differentiation and cell growth and on normal embryonic development. Intracellular retinoid signaling induced by endogenous or exogenous RA is regulated by retinoid binding proteins such as CRBPI, CRABPI and CRABPII and there are data suggesting that the expression of these proteins can influence the sensitivity to the growth inhibitory effects of ATRA. In this study, we investigated the basal and ATRA-induced expression of CRBPI and CRABPI and II in leukemic cell lines and in cells from patients with acute myeloid leukemia (AML). CRBPI as well as CRABPI and II were expressed in all tested cell lines and in leukemic cells from all 18 AML-patients. CRABPII mRNA expression was more abundant than CRBPI and CRABPI in both the cell lines and the patient cells but the levels compared the house keeping gene was lower in the patient cells. In all cell lines and in 69% of the patient samples, ATRA did upregulate CRABPII whereas CRBPI exhibited a varying response and CRABPI was more commonly downregulated. The sensitivity to the growth inhibitory effects of ATRA did not correlate with the basal expression of any of these proteins. However, ATRA-induced upregulation of CRABPII did significantly correlate with the ATRA sensitivity (p < 0.005) as well as with ATRA-induced upregulation of the retinoid receptor RARbeta (p < 0.05). We conclude that the retinoid binding proteins CRBPI and CRABPI and II are expressed in myeloid leukemic cells of non-M3 type but that the level of expression does not affect ATRA sensitivity.
 ...
PMID:The expression of cellular retinoid binding proteins in non-APL leukemic cells and its association with retinoid sensitivity. 1215 75

The use of intensive therapy overa brief period of time has produced dramatic improvements in outcome for pediatric patients with acute myelogenous leukemia (AML), as has been demonstrated in studies by the major cooperative groups in the United States and Europe. Still, despite high-intensity chemotherapy and bone marrow transplantation, only about half of the children diagnosed with AML are cured. Future improvements are unlikely to come from further increases in chemotherapy intensity. Alternative approaches, such as risk-directed therapy based on different prognostic criteria; differentiation therapy with all-trans-retinoic acid (ATRA, Vesanoid), arsenic trioxide (Trisenox), or azacytidine; and immunotherapy with monoclonal antibodies, tumor vaccines, or cytokines may lead to further advances.
 ...
PMID:What is the optimal therapy for childhood AML? 1220 45

Retinoic acid (RA) promotes granulocytic differentiation of normal hematopoietic cells and acute promyelocytic leukemia (APL) blasts by transcriptional modulation of myeloid regulatory genes. In this study, we have identified the C/EBP homologous protein (CHOP) as a novel retinoid-responsive gene using a polymerase chain reaction (PCR)-based cDNA subtraction method. All-trans retinoic acid (ATRA) induced a biphasic expression of CHOP mRNA in the NB4 and HL60 AML cell lines. Levels of CHOP expression increased within 1 hour of exposure to ATRA. ATRA expression became nearly absent between 6 and 24 hours, and a second phase of induction occurred after 48 hours. Retinoid-dependent regulation of CHOP expression was also observed in normal human neutrophils but not in peripheral blood mononuclear cells. In addition, retinoid-dependent regulation of CHOP expression was not observed in retinoid-nonresponsive cell lines HL60R and NB4-R2. CHOP expression was regulated at the transcriptional level and was independent of new protein synthesis. CHOP heterodimerized with C/EBPepsilon and negatively regulated the myeloid-specific gene lactoferrin. Furthermore, CHOP transcriptionally inhibited C/EBPalpha- and C/EBPepsilon-dependent induction of secondary granule gene expression. RA signaling in granulocytic differentiation involves regulated expression of CHOP and C/EBPepsilon in a coordinated fashion.
 ...
PMID:Retinoic acid regulates C/EBP homologous protein expression (CHOP), which negatively regulates myeloid target genes. 1530 77


<< Previous 1 2 3 Next >>