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Biomedical subjects

L Degos

Publications and source records attributed to L Degos.

At least 73 records · Page 4Linked to original sources
PubMed1995

Characterization of nuclear retinoic acid binding activity in sensitive leukemic cell lines: cell specific uptake of ATRA and RAR alpha protein modulation.

The diverse effects of all-trans retinoic acid (ATRA) on growth, differentiation and homeostasis of vertebrate organisms are mediated by three distinct isoforms of retinoic acid receptors (RARs). Although it is not known to what extent each RAR contributes to the different effects of ATRA, several studies have demonstrated that ATRA induced granulocytic differentiation in human myeloid leukemic cell lines is mediated by RAR alpha. In this study, we investigated ATRA binding affinity of the endogenous nuclear receptors of HL-60 and NB4 leukemic cells. Scatchard plot analysis yielded an apparent dissociation constant of 5 +/- 0.3 nM and 1400 +/- 80 receptor sites per cell in HL-60 cells, whereas the NB4 promyelocytic leukemic cell line showed a lower affinity (8.5 +/- 0.5 nM and 900 +/- 30 receptor sites per cell). Modulation of RAR alpha protein (5 fold excess) was found in NB4 cells after 24 hours ATRA exposure, whereas HL-60 cells required a 72-hour culture period to weakly increase the RAR alpha protein level. These data were closely related to the ATRA intracellular concentration and kinetics of terminal differentiation of the cells.

Animals↗
PubMed1995

Simultaneous determination of all-trans and 13-cis retinoic acids and their 4-oxo metabolites by adsorption liquid chromatography after solid-phase extraction.

All-trans retinoic acid (all-trans RA), the active metabolite of vitamin A, has been demonstrated to be an efficient alternative to chemotherapy in the treatment of acute promyelocytic leukemia (APL), the AML3 subtype of the FAB cytological classification. Complete remission is obtained by inducing terminal granulocytic differentiation of the leukemic cells. To study all-trans RA pharmacokinetics in patients with APL, a rapid, precise and selective high-performance liquid chromatographic (HPLC) assay was developed. This method is easy and shows good repeatability (C.V. = 8.41-12.44%), reproducibility (C.V. = 9.19-14.73%), accuracy (C.V. = 3.5-11%) and sensitivity with a detection limit of 5 pmol/ml. The analysis is performed using normal-phase HPLC in an isocratic mode with UV detection after solid-phase extraction on octadecyl (C18) columns. The mobile phase is hexane-dichloromethane-dioxane (78:18:4, v/v) containing 1% acetic acid.

Adsorption↗
PubMed1995

The PML growth-suppressor has an altered expression in human oncogenesis.

Altered sub-nuclear localisation of the nuclear body-associated PML protein in acute promyelocytic leukaemia, has been proposed to contribute to leukaemogenesis. We have recently shown that PML is a primary target gene of interferons. Here, it is shown that PML has growth suppressive properties and displays an altered expression pattern during human oncogenesis. PML is widely expressed in cell-lines and is cell-cycle regulated. Overexpression of the protein induces a sharp reduction in growth rates in vitro and in vivo. In contrast with cell-lines, in normal tissues (including those that rapidly proliferate) only a few cells have detectable PML levels. However, these can be upregulated by soluble factors (e.g. IFN, estrogens). Human epithelial tumors show a gradual increase of PML levels as the lesion progresses from benign dysplasia to carcinoma. A similar induction is found in the surrounding stroma and vessels, which likely results from paracrine interactions. Strikingly, when malignant cells turn invasive, they loose PML expression, while expression is conserved in the stromal compartment. These observations point to the existence of a consistent deregulation in the expression of the PML growth-suppressor during human oncogenesis.

Animals↗
PubMed1995

Unexpected high incidence of intracranial subdural haematoma during intensive chemotherapy for acute myeloid leukaemia with a monoblastic component.

We report a high incidence of subacute, chronic and sometimes occult intracranial subdural haematoma (SDH) occurring during intensive chemotherapy for acute myeloid leukaemia (AML) with a monoblastic component. Between March 1990 and January 1993, 86 AML patients from our institution were randomized in the multicentric French AML 90 trial. Eight patients (9%) presented a grade > 2 haemorrhagic event, which was intracranial SDH in five of them. All these five SDH patients had hyperleucocytic AML4 or AML5 and had experienced at least one lumbar puncture (LP) before SDH diagnosis (with intrathecal chemotherapy in four cases). SDH diagnosis was assessed on a brain computed tomography scan which was performed 1-9 d after initial SDH symptoms (mainly mild headaches considered a result of prior LP). All these five patients recovered from this severe event after a specified therapy. SDH does not appear to be an uncommon complication of AML4 and AML5 therapy. Its incidence might be under-reported because of poor symptomatology. Lumbar punctures, known to cause exceptional SDH in nonleukaemic patients, might trigger these haemorrhagic events, eventually in combination with other predisposing factors such a haemostasis disorders or leukaemic CNS infiltration.

Acute Disease↗
PubMed1995

All-trans retinoic acid pharmacokinetics and bioavailability in acute promyelocytic leukemia: intracellular concentrations and biologic response relationship.

PURPOSE: This study investigated the in vitro pharmacologic behavior and disposition kinetics of all-trans retinoic acid (ATRA) in acute myeloid leukemic (AML) cells, their sensitivity to its differentiating effect, and the in vivo response of acute promyelocytic leukemia (APL) patients after therapy. PATIENTS AND METHODS: Fresh leukemic cells from 14 AML patients (nine APL and five non-APL), were incubated in suspension culture in the absence or presence of 10(-6) mol/L ATRA. Intracellular ATRA concentration and ATRA metabolism was determined by high-performance liquid chromatography (HPLC). RESULTS: Immediate uptake is observed with maximal intracellular levels (Cmax) achieved after 24 hours of incubation. At this time, ATRA levels were variable, ranging from 20 to 230 pmol/10(6) cells (median, 100 pmol/10(6) cells). Comparison of ATRA intracellular levels with the in vitro response of patients' cell samples as measured by the percentage of nitro blue tetrazolium (NBT)-positive cells after a 3-day incubation period allowed us to discriminate a group of APL patients (n = 6) with high Cmax (group A; median, 200 pmol/10(6) cells) and maximal differentiation at day 3 (median, 80%), and a group of patients (n = 8, three APL and five non-APL) with low Cmax (group B; median, 35 pmol/10(6) cells) and poor in vitro response (median, 40%; APL cases only). Interestingly, all APL patients, except one included in group A (rapid in vitro ATRA uptakers), achieved a complete remission. CONCLUSION: These findings suggest that intracellular ATRA concentrations are determinant for ATRA response and should be taken into account when monitoring the efficacy of ATRA differentiation therapeutic trials in malignant disorders.

Adolescent↗
PubMed1995

Treatment of newly diagnosed acute promyelocytic leukemia (APL) by all transretinoic acid (ATRA) combined with chemotherapy: The European experience. European APL Group.

All transretinoic acid (ATRA) gives complete remission (CR) rates of 80 to 90% in newly diagnosed acute promyelocytic leukemia (APL). However, it has two major drawbacks (1) a rapid rise in WBC in some patients, with potentially fatal ATRA syndrome (2) rapid relapse with maintenance therapy using ATRA alone or low dose chemotherapy. The French APL group therefore designed a treatment approach with ATRA followed by intensive chemotherapy. The latter was administered after CR achievement with ATRA, or was rapidly added to ATRA in case of rapid rise in leukocyte counts. This combined approach, in a pilot study and in a randomized trial, proved superior to intensive chemotherapy alone, by slightly increasing the CR rate but more importantly by reducing the relapse rate. These results were confirmed by the Chinese, Japanese and New York groups. Our group (and other European groups) are now testing in a new randomized trial the better timing of ATRA and chemotherapy administration (ATRA followed by chemotherapy or ATRA plus chemotherapy) and the role (after an intensive consolidation) of maintenance treatment with intermittent ATRA, continuous low dose chemotherapy or both.

Adult↗
PubMed1995

In vivo thrombin and plasmin activities in patients with acute promyelocytic leukemia (APL): effect of all-trans retinoic acid (ATRA) therapy.

APL-associated hemostasis disorders result from at least two distinct mechanisms due to the release of procoagulant activities and plasminogen activators from the leukemic cells. These two mechanisms (thrombin activation and plasmin activation) may cleave the fibrinogen molecule, but their respective roles in low fibrinogen levels and bleeding diathesis genesis remain in dispute. In vivo ATRA therapy induces a rapid correction of both low fibrinogen level and bleeding tendency, but no clear explanation of this beneficial effect has been proposed. We prospectively investigated 27 APL patients at presentation for diffuse intravascular coagulation (DIC) markers (prothrombin activation fragment and thrombin/antithrombin complexes) and plasmin-dependent primary fibrinogenolysis markers (alpha 2 plasmin inhibitor consumption +/- plasmin/alpha 2 plasmin inhibitor complexes). Fourteen of these patients were then serially studied during the first 2 weeks of ATRA therapy. Four of them, however, developed an hyperleukocytosis requiring additional chemotherapy before the end of the 2nd week. At presentation, low level of fibrinogen was clearly associated with alpha 2 plasmin inhibitor deficiency (p < 0.01), while DIC was equally present in fibrinogenopenic and non-fibrinogenopenic patients. Moreover, was observed a rapid simultaneous correction of low fibrinogen levels and plasmin activation markers in APL patients undergoing ATRA therapy (before day 5), but a more prolonged persistence of DIC markers (until day 14). Initial bleeding syndrome seemed more frequent in patients with initial low fibrinogen level. These data indicate that plasmin-dependent primary fibrinogenolysis is the major etiologic factor of low fibrinogen level in APL patients. In vivo differentiation ATRA therapy induces a rapid decrease in the plasmin activation and a normalization of fibrinogen level, while DIC may in vivo persist for several weeks. Prospective studies evaluating antifibrinolytic agents as therapy of APL-associated hemostasis disorders should be considered. Additionally, prophylactic heparin therapy might be useful after day 5 in patients undergoing ATRA therapy, since they present a prolonged procoagulant tendency.

Adolescent↗
PubMed1995

Neutrophilic dermatoses during granulocytopenia.

BACKGROUND AND DESIGN: Noninfectious cutaneous neutrophilic lesions can occur during granulocytopenia, but their mechanism remains unknown. We undertook a retrospective study of the neutrophilic dermatoses that developed during granulocytopenia induced by chemotherapy for acute myelogenous leukemia. RESULTS: Seven men and one woman were included (2.6% of treated cases of acute myelogenous leukemia); half had acute myelogenous leukemia subtypes 4 and 5. The male-to-female ratio was 7:1. Neutrophilic eccrine hidradenitis was diagnosed in five cases, Sweet's syndrome in two cases, and difficult-to-classify neutrophilic dermatoses in one case. Cutaneous lesions appeared 12.5 days after the start of chemotherapy, and the mean leukocyte count was 0.426 x 10(9)/L. Three patients needed corticosteroids systemically. CONCLUSION: Neutrophilic dermatoses during chemotherapy-induced granulocytopenia seem to occur more frequently in men with acute myelogenous leukemia subtypes 4 and 5.

Adult↗
PubMed1995

Changes in microrheology of acute promyelocytic leukemia cells during all-trans retinoic acid (ATRA) differentiation therapy: a mechanism for ATRA-induced hyperleukocytosis?

According to French and European experience, hyperleukocytosis occurs during ATRA differentiation therapy in about 70% of de novo and 25% of relapsed APL cases. The most frequently suggested cause for this side-effect is an ATRA-induced proliferation of APL cells. However, no definite explanation for such a proliferative effect has been clearly established. Another mechanism directly related to the differentiation of marrow leukemic cells could be a change in their microrheology, allowing their release from the bone marrow and their transfer toward peripheral blood (PB) and tissues. Using a single cell aspiration assay into a glass restrictive channel, we measured APL cell viscosity values in five de novo APL patients. A deformability index (DI) was defined as the ratio of mean normal neutrophil viscosity x 100/mean APL cell viscosity. Results were the following: (1) at diagnosis, two patients had high marrow DI (96 and 250%) and three patients had low marrow DI (16, 17, and 40%); (2) when PB and marrow APL cells were simultaneously tested, PB APL cells display higher DI than marrow APL-cells; (3) the two patients with high initial marrow DI experienced an ATRA-induced hyperleukocytosis after only 1 day of treatment; (4) in the three patients with low initial marrow DI, the DI was increasing during ATRA therapy and hyperleukocytosis seemed to occur when a large amount of maturing APL cells reached a viscosity value similar to that of mature neutrophils. These results suggest that an asynchronism between rheological and morphological maturation in each APL cell might explain the occurrence of hyperleukocytosis in some patients during ATRA differentiation therapy.

Adult↗
PubMed1995

Differential uptake of all-trans retinoic acid by acute promyelocytic leukemic cells: evidence for its role in retinoic acid efficacy.

All-trans retinoic acid (ATRA) has been demonstrated to be an efficient alternative to chemotherapy in the treatment of acute promyelocytic leukemia (APL or AML3). Complete remission is obtained by inducing granulocytic differentiation of the leukemic cells. To date, the exact mechanism through which ATRA exerts its differentiating effect is not known. The present investigation was initiated to characterize ATRA intracellular concentrations achieved in human myeloid leukemic cells in relation to their different sensitivity to ATRA differentiating effect. During the first 24 h of incubation, a significant decrease of ATRA in the culture medium and a marked increase in the intracellular concentrations were observed. Maximal uptake by the leukemic cells was reached within minutes, with levels between 20 and 260 pmol/10(6) cells (median = 100). Interestingly, a correlation between ATRA-induced differentiation and the intracellular ATRA concentration achieved was observed. In fact, patients with intracellular levels below 60 pmol/10(6) cells defined slow uptakers, never exceeded 40% differentiated cells at day 3. On the other hand, cells with 2-4-fold higher concentration (100-250 pmol/10(6) cells) achieved 100% differentiated cells at day 3. This report suggests that intracellular ATRA concentration is a key pharmacological parameter that should be taken into account to gain further insights into ATRA sensitivity in APL patients.

Adolescent↗
PubMed1995

[Treatment of acute promyelocytic leukemia by all trans retinoic acid].

It has been shown in vitro that retinoids and especially all-trans retinoic acid (ATRA) were able to induce maturation of malignant cells from patients with acute promyelocytic leukemia (APL). Clinical studies have confirmed in vitro observations. Oral administration of ATRA is able to induce complete remissions in the majority of APL patients, either treated de novo or after failure of conventional chemotherapy. Complete remission are observed by a differentiation process and ATRA therapy in APL represents the first model of differentiation therapy. The major adverse effect of ATRA treatment is the occurrence in some cases of a "retinoic acid syndrome" associated with rapidly, progressive rise of leukocytes. This syndrome is corrected by the addition of chemotherapy. A progressive acquired resistance appears during ATRA treatment and for this reason post remission chemotherapy is indispensable. The superiority of the combination of ATRA+chemotherapy over chemotherapy alone for the incidence of relapse and for survival duration has been established in a randomized European trail (APL 91).

Female↗
PubMed1995

Induction of the PML protein by interferons in normal and APL cells.

PML has been identified through its fusion to the RAR alpha gene in acute promyelocytic leukemia (APL). The PML protein is specifically associated to nuclear bodies (NBs) whose alterations in APL were proposed to contribute to leukemogenesis. The role of this nuclear domain (which also harbors the Sp100 autoantigen and the NDP52 protein) is unknown. Here, we show that the PML protein, like Sp100 and NDP52, is induced by interferons (IFNs alpha, beta and gamma) in a large variety of human cells. Interestingly, the NBs that contain the three IFN-induced proteins appear to be associated to speckles labelled by the IFN-mediator Mx1. These observations link NBs to IFN response pathways, which may contribute to the elucidation of the biological role of these structures. In APL cells, IFNs induced both PML and PML/RAR alpha expression, resulting in an increased sequestration of PML and RXRs in the microspeckles induced by the fusion protein. As PML has growth suppressing properties, it may mediate some of the antiproliferative effects of IFN. In APL, inactivation of PML may result in disruption of growth control.

Antineoplastic Agents↗
PubMed1995

In vitro treatment with retinoids or the topoisomerase inhibitor, VP-16, evidences different functional apoptotic pathways in acute promyelocytic leukemic cells.

Understanding the mechanisms inherent to malignant cell eradication is a major determinant for cancer therapy. Recent data have demonstrated that apoptosis may be one of the mechanisms through which both cytotoxic and differentiating drugs may eliminate malignant cells. Treatment of acute promyelocytic leukemia (APL) by all-trans retinoic acid (ATRA) is the first model of differentiation therapy allowing achievement of more than 90% complete remission (CR). However, disease-free survival (DFS) is short if patients are not subsequently treated with chemotherapy. In order to address the question of APL cells' elimination during ATRA therapy, we studied phenotypic and molecular features of 14 APL cases relative to cell survival in primary culture in the presence or absence of ATRA. Compared to other acute myeloid leukemia (AML) subtypes, APL cells in short-term suspension culture present a better survival rate (P < 0.001). After incubation with ATRA, cell survival was not altered and was correlated with a concomitant absence of apoptosis, despite a significant decrease of the BcL-2 protein in APL differentiated cells. Indeed, after 6 days of culture, only 3 +/- 0.5% of APL cells exhibit morphological features of apoptosis after ATRA treatment compared to 30 +/- 5% in HL-60-treated cells. Treatment of APL cells with 9-cis RA, 13-cis RA or analogs of RAR alpha or RXR alpha also failed to induce apoptosis. Treatment of either APL or ATRA-differentiated APL cells with 40 microM etoposide resulted in DNA fragmentation and morphological changes characteristic of apoptosis in 23 +/- 5% cells after only 20 h of treatment and 68 +2- 3% after 48 h suggesting that other pathways of apoptosis are still functional in APL cells. Though these in vitro data cannot fully represent the mechanism of cell death and cell elimination in vivo, they clearly indicate that ATRA alone may not induce leukemic clone eradication by apoptosis correlating with the persistence of minimal residual disease and constant relapse after CR obtained with ATRA alone.

Apoptosis↗
PubMed1995

[A new concept: treatment using differentiation of the malignant cell in man].

Against the dogma of the irreversibility of malignant cells, although genetical abnormalities, human leukemic cells have been differenciated. According to Leo Sachs proposals on the proliferation-differentiation balance impairment in malignancies we have shown various orientation for the differentiation therapy: inhibition of malignant cells using low dose of Cytosine Arabinoside in acute myeloid leukemia; suppression of the growth factor effect such as the role of interferon in hairy cell leukemia; targetted differentiation process by all trans retinoic acid in acute promyelocytic leukemia with the obtention of complete remission in all cases; differentiation of malignant and normal cells by G-CSF in acute myeloid leukemia in elderly patients. Differentiation therapy induces a modulation in the cell program. Cells mature, becoming differentiated, die, disappear and are replaced by normal cells. The addition of differentiation treatment to chemotherapy greatly improves the chance of long term survival.

Adolescent↗
PubMed1994

Selective induction of apoptosis in myeloid leukemic cell lines by monoacetone glucose-3 butyrate.

Butyric acid is a potent cell growth inhibitor and differentiation inducer. Our previous studies have shown that MAG=3but, a monosaccharide ester of butyric acid, used at 1 mM, induces apoptosis in the HL-60 cell line. We report here that this drug can also induce apoptosis in the U-937 leukemic cell lines whereas the myeloblastic KG1 and the NB4 promyelocytic leukemic cell lines were refractory to induction of apoptosis. In order to determine what can trigger cells to undergo apoptosis, cell cycle analysis, induction of differentiation and p53, c-myc and Bcl-2 expression was studied. Apoptosis was correlated to an arrest of cell growth in the G1 phase of the cell cycle and to an induction of differentiation through the monocytic pathway in HL-60 and U-937 cells. Time course studies demonstrated DNA fragmentation after few hours incubation with the drug, while morphological signs appeared later (days 2 or 3). Northern blot analysis and flow cytometric studies have shown that cell death induced by MAG=3but was not associated to an overexpression of c-myc and p53. However, in the HL-60 cells, BCL-2 protein expression was decreased after MAG=3but treatment, corroborating the apoptosis observed.

Apoptosis↗
PubMed1994

[Retinoid receptors and hematologic diseases].

Acute promyelocytic leukemia is a rare disease combining a specific cell type, a bleeding diathesis and a translocation t(15;17). All trans retinoic acid is able to induce a maturation of malignant cells, up to terminal differentiation. After 2 months of treatment a complete remission is obtained without any aplastic anemia. The bleeding diathesis rapidly disappears. However relapses occur within few months due to the catabolism of retinoic acid induced by the treatment itself. A chemotherapy is generally proposed, in order to consolidate the complete remission. The combination of retinoic acid and chemotherapy has dramatically increased the probability of long term survival. The breakpoint of the translocation t(15;17) is located inside the retinoic acid receptor gene on chromosome 17. A new product is made, due to the fusion of the truncated retinoic acid receptor and a gene on chromosome 15. The hybrid product blocks the program normally performed by the retinoic acid receptor and consequently blocks the maturation of the granulocytes. Why pharmacological doses restore the impaired program is still an enigma.

Humans↗