Biomedical subjects

L Cleris

Publications and source records attributed to L Cleris.

14 recordsLinked to original sources

PubMed2003

Effect of imatinib on haematopoietic recovery following idarubicin exposure.

SCF is a potent pro-proliferative cytokine crucial for haematopoiesis, which binds to c-kit and activates its tyrosine kinase activity. Inactivating mutations of either SCF or c-kit have been described in mice and lead to increased sensitivity to treatment with ionising radiation. Imatinib is a tyrosine kinase inhibitor with high affinity for c-Abl, PDGFR and c-kit. In this study we investigated the effect of concomitant administration of imatinib and idarubicin, an anthracycline with haematosuppressive activity, in nu/nu mice and murine bone marrow cells. Double-treated animals showed significantly increased mortality compared to mice that received imatinib or idarubicin alone only when idarubicin and imatinib were given simultaneously. The combined treatment induced a more severe neutropenia with a slower recovery when compared to mice treated with idarubicin alone. The myeloid metaplasia usually observed in the spleen after idarubicin treatment was absent in mice co-treated with imatinib. Bone marrow from double-treated animals also showed decreased numbers of megakaryocytes and myeloid precursor cells. In vitro culture of murine bone marrow cells in the presence of imatinib inhibited SCF-induced proliferation and recovery from treatment with idarubicin. Our results indicate that the simultaneous administration of imatinib enhances idarubicin-induced haematopoietic toxicity in vivo and in vitro.

Animals↗

PubMed2001

Decrease in drug accumulation and in tumour aggressiveness marker expression in a fenretinide-induced resistant ovarian tumour cell line.

We investigated whether the efficacy of fenretinide (HPR) against ovarian tumours may be limited by induction of resistance. The human ovarian carcinoma cell line A2780, which is sensitive to a pharmacologically achievable HPR concentration (IC(50)= 1 microM), became 10-fold more resistant after exposure to increasing HPR concentrations. The cells (A2780/HPR) did not show cross-resistance to the synthetic retinoid 6-[3-adamantyl-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437) and were not sensitive, similarly to the parent line, to all-trans-retinoic acid, 13-cis-retinoic acid or N-(4-methoxyphenyl)retinamide. A2780/HPR cells showed, compared to parental cells, a 3-fold reduction in colony-forming ability in agar. The development of HPR resistance was associated with a marked increase in retinoic acid receptor beta (RARbeta) mRNA and protein levels, which decreased, together with drug resistance, after drug removal. The expression of cell surface molecules associated with tumour progression including HER-2, laminin receptor and beta1 integrin was markedly reduced. The increase in the levels of reactive oxygen species is not involved in HPR-resistance because it was similar in parental and resistant cells. Conversely differences in pharmacokinetics may account for resistance because, in A2780/HPR cells, intracellular peak drug levels were 2 times lower than in A2780 cells and an as yet unidentified polar metabolite was present. These data suggest that acquired resistance to HPR is associated with changes in marker expression, suggestive of a more differentiated status and may be explained, at least in part, by reduced drug accumulation and increased metabolism.

Antineoplastic Agents↗

PubMed2001

Growth-inhibitory effect of STI571 on cells transformed by the COL1A1/PDGFB rearrangement.

Dermatofibrosarcoma protuberans (DP) is a skin tumor of intermediate malignancy characterized by high recurrence rates, for which surgical excision is the main therapy. All DP cases carry a specific t(17;22) translocation, resulting in a COL1A1/PDGFB rearrangement. The subsequently deregulated production of PDGFB generates autocrine stimulation of PDGFrbeta, leading to malignant transformation. Using NIH-3T3 cells transformed by the COL1A1/PDGFB rearrangement (5A cell line), we explored the possibility of blocking the PDGFB autocrine loop, both in vitro and in vivo, using STI571, an inhibitor of the PDGF receptor and of ABL kinase activity. The presence of small amounts of serum in the culture medium was required for the in vitro growth and morphological transformation of 5A cells. In the presence of STI571, the growth rate was reduced and the associated transformed phenotype changed to a flattened one. This effect could be reversed on removal of the inhibitor. The growth rate of tumors induced by 5A cells in nude mice was reduced by STI571 administration. Interestingly, this effect was also evident on pre-existing tumors, but no tumor eradication was observed. This is consistent with the reversible effects of the inhibitor observed in vitro but differs from the eradication effect of STI571 on BCR-ABL-induced tumors. Our data indicate that STI571 might be a candidate compound for the pharmacological treatment of DP and demonstrate that the same compound may act in different ways (cytotoxic vs. cytostatic), according to the specificity of the inhibited tyrosine kinase, namely, ABL or PDGFrbeta.

3T3 Cells↗

PubMed2000

Role of alpha1 acid glycoprotein in the in vivo resistance of human BCR-ABL(+) leukemic cells to the abl inhibitor STI571.

BACKGROUND: Chronic myeloid leukemia is caused by a chromosomal translocation that results in an oncogenic fusion protein, Bcr-Abl. Bcr-Abl is a tyrosine kinase whose activity is inhibited by the antineoplastic drug STI571. This drug can cure mice given an injection of human leukemic cells, but treatment ultimately fails in animals that have large tumors when treatment is initiated. We created a mouse model to explore the mechanism of resistance in vivo. METHODS Nude mice were injected with KU812 Bcr-Abl(+) human leukemic cells. After 1 day (no evident tumors), 8 days, or 15 days (tumors >1 g), mice were treated with STI571 (160 mg/kg every 8 hours). Cells recovered from relapsing animals were used for in vitro experiments. Statistical tests were two-sided. RESULTS: Tumors regressed initially in all STI571-treated mice, but all mice treated 15 days after injection of tumor cells eventually relapsed. Relapsed animals did not respond to further STI571 treatment, and their Bcr-Abl kinase activity in vivo was not inhibited by STI571, despite high plasma concentrations of the drug. However, tumor cells from resistant animals were sensitive to STI571 in vitro, suggesting that a molecule in the plasma of relapsed animals may inactivate the drug. The plasma protein alpha1 acid glycoprotein (AGP) bound STI571 at physiologic concentrations in vitro and blocked the ability of STI571 to inhibit Bcr-Abl kinase activity in a dose-dependent manner. Plasma AGP concentrations were strongly associated with tumor load. Erythromycin competed with STI571 for AGP binding. When animals bearing large tumors were treated with STI571 alone or with a combination of STI571 and erythromycin, greater tumor reductions and better long-term tumor-free survival (10 of 12 versus one of 13 at day 180; P:<.001) were observed after the combination treatment. CONCLUSION: AGP in the plasma of relapsed animals binds to STI571, preventing this compound from inhibiting the Bcr/Abl tyrosine kinase. Molecules such as erythromycin that compete with STI571 for binding to AGP may enhance the therapeutic potential of this drug.

Animals↗

PubMed2000

Therapeutic effects of the combination of fenretinide and all-trans-retinoic acid and of the two retinoids with cisplatin in a human ovarian carcinoma xenograft and in a cisplatin-resistant sub-line.

We previously showed that fenretinide (4-HPR), a synthetic derivative of all-traits retinoic acid (RA), is effective in mice bearing the human ovarian carcinoma IGROV-1 and it significantly enhances the antitumour activity of cisplatin on the same tumour. The present study examined the therapeutic effects of the combination of 4-HPR and RA and of the two retinoids with cisplatin as intracavitary treatments of mice bearing IGROV-1 and IGROV-1/cisplatin tumours, the latter derived from a sub-line with an in vivo reduced sensitivity to cisplatin. 4-HPR, as a single agent, was effective against both tumours, whereas RA had no effect. In IGROV-1 tumour-bearing mice, the combination of RA and 4-HPR significantly improved the efficacy of 4-HPR, resulting in an antitumour activity similar to that obtained with cisplatin alone. N-(4-methoxyphenylretinamide), the main metabolite of 4-HPR, had no antitumour effect and it did not increase 4-HPR activity in IGROV-1 tumour-bearing mice. In the same tumour model, 4-HPR and RA separately increased cisplatin activity, even though for RA the increase was not statistically significant. In contrast, the association of the two retinoids together with cisplatin did not produce any benefit and resulted in increased toxicity. In IGROV-1/cisplatin tumour-bearing mice, the association of 4-HPR (but not of RA) to cisplatin significantly increased cisplatin activity, resulting in the reversal of cisplatin resistance. These findings demonstrate that 4-HPR may be effective and enhance cisplatin sensitivity in cisplatin-sensitive and -resistant ovarian tumours and that the association of RA and 4-HPR may result in increased 4-HPR antitumour activity.

Animals↗

PubMed1999

Role of retinoic acid receptor overexpression in sensitivity to fenretinide and tumorigenicity of human ovarian carcinoma cells.

The role of retinoic acid receptor (RAR) expression in sensitivity to N-(4-hydroxyphenyl)retinamide (4HPR or fenretinide) as well as on the tumorigenicity of human ovarian carcinoma cells was examined. Two human ovarian cancer cell lines, A2780 and IGROV-1, with a 10-fold difference in sensitivity to 4HPR were chosen to study RAR involvement in the response to 4HPR. To determine which RAR was effective, RARalpha, beta and gamma were individually overexpressed in A2780 cells, which are the most sensitive to 4HPR. Sensitivity to 4HPR was increased in RARbeta-overexpressing clones, whereas it was slightly decreased in RARalpha transfectants (which had diminished RARbeta expression) and was unchanged in clones transfected with RARgamma. IGROV-1 cells, which are RARbeta negative, were transfected with RARbeta. Surprisingly, none of the obtained IGROV-1 RARbeta transfectants expressed RARbeta protein, in spite of RARbeta mRNA transcription. All clones were similar to the parental IGROV-1 cells in their sensitivity to 4HPR. Treatment with a pharmacologically achievable concentration of 4HPR (1 microM) led to a rapid 2-fold increase in RARbeta mRNA levels in A2780 cells, but it did not induce RARbeta expression in IGROV-1 cells. Analysis of the tumorigenicity of A2780-transfected clones revealed that overexpression of RARalpha was associated with a significant reduction in tumor takes (50% and 67%, respectively, vs. 96% for the parent line) and with a reduced growth rate. Oncogenicity was clearly decreased in only 1 of the 2 RARbeta-overexpressing clones (33% takes) and was unchanged in the 2 clones with increased RARgamma expression. Our results demonstrate that basal expression and 4HPR inducibility of RARbeta play a role in mediating 4HPR response in ovarian cancer cells. The findings of reduced oncogenicity of clones overexpressing RARalpha and of one clone overexpressing RARbeta indicate that RARalpha and RARbeta might have a tumor-suppressive effect in ovarian tumors.

Antineoplastic Agents↗

PubMed1999

In vivo eradication of human BCR/ABL-positive leukemia cells with an ABL kinase inhibitor.

BACKGROUND: The leukemia cells of approximately 95% of patients with chronic myeloid leukemia and 30%-50% of adult patients with acute lymphoblastic leukemia express the Bcr/Abl oncoprotein, which is the product of a fusion gene created by a chromosomal translocation [(9:22) (q34;q11)]. This oncoprotein expresses a constitutive tyrosine kinase activity that is crucial for its cellular transforming activity. In this study, we evaluated the antineoplastic activity of CGP57148B, which is a competitive inhibitor of the Bcr/Abl tyrosine kinase. METHODS: Nude mice were given an injection of the Bcr/Abl-positive human leukemia cell lines KU812 or MC3. Tumor-bearing mice were treated intraperitoneally or orally with CGP57148B according to three different schedules. In vitro drug wash-out experiments and in vivo molecular pharmacokinetic experiments were performed to optimize the in vivo treatment schedule. RESULTS: Treatment schedules administering CGP57148B once or twice per day produced some inhibition of tumor growth, but no tumor-bearing mouse was cured. A single administration of CGP57148B caused substantial (>50%) but short-lived (2-5 hours) inhibition of Bcr/Abl kinase activity. On the basis of the results from in vitro wash-out experiments, 20-21 hours was defined as the duration of continuous exposure needed to block cell proliferation and to induce apoptosis in these two leukemia cell lines. A treatment regimen assuring the continuous block of the Bcr/Abl phosphorylating activity that was administered over an 11-day period cured 87%-100% of treated mice. CONCLUSION: These data indicate that the continuous block of the oncogenic tyrosine kinase of Bcr/Abl protein is needed to produce important biologic effects in vivo.

Animals↗

PubMed1996

Induction of apoptosis by fenretinide (4HPR) in human ovarian carcinoma cells and its association with retinoic acid receptor expression.

We previously reported that fenretinide (4HPR) is effective against a human ovarian carcinoma xenografted in nude mice. The effects of 4HPR on ovarian tumors have been further studied in in vitro ovarian carcinoma cell lines A2780, IGROV-I, SW626 and OVCA432. A2780 was the most sensitive line: 50% growth inhibition was obtained after 3 days of exposure to 1 microM 4HPR, a pharmacologically achievable concentration, whereas approx. 10 microM 4HPR gave a similar inhibition in the other cell lines. All-trans retinoic acid (RA), at doses up to 10 microM, did not inhibit cell proliferation. Gel electrophoresis of DNA from either detached or attached A2780 cells treated with 4HPR revealed DNA ladders in detached cells. Apoptosis was also evidenced in detached 4HPR-treated cells by flow cytometry and microscopic observation. The difference in cell line sensitivity to the anti-proliferative effect of 4HPR was not related to drug uptake or efflux. Only A2780 cells, the most sensitive to 4HPR, expressed constitutive levels of RARbeta; moreover, the levels of RARalpha and RARgamma expression in these cells were higher than in the other cell lines. In A2780 cells, the association of an IC20 of 4HPR to cisplatin resulted in a strong potentiation of the anti-proliferative effect. These data show (i) that 4 HPR, in contrast to RA, has an anti-proliferative effect in human ovarian carcinoma cells which is related to induction of apoptosis and (ii) that among the tested lines, the most responsive to the drug expressed RARbeta and the highest levels of RARalpha and RARgamma. The results also suggest that 4HPR can potentiate the effects of cisplatin in ovarian carcinoma.

Antineoplastic Agents↗

PubMed1995

Modulation of markers associated with tumor aggressiveness in human breast cancer cell lines by N-(4-hydroxyphenyl) retinamide.

The retinoid N-(hydroxyphenyl) retinamide (4-HPR) appears to be a promising tool for chemoprevention of breast carcinoma, and clinical trials to evaluate its effect are in progress. However, its action on tumor cells has remained largely undefined. We report here that 4-HPR induced apoptosis and/or differentiation in breast cancer cell lines, independent of hormone receptor status and retinoic acid receptor expression, although it was slightly more efficient in inhibiting proliferation of estrogen receptor-positive cells. 4-HPR up-modulated expression of several differentiation markers (class 1 HLA, laminin, and beta 1 integrin chain) and down-regulated expression of molecules associated with tumor progression, including the p185/HER2 oncoprotein, the epidermal growth factor receptor, and the M(r) 67,000 laminin receptor. These data suggest that 4-HPR could exert a beneficial effect by inhibiting cell proliferation and modulating breast tumor aggressiveness.

Anticarcinogenic Agents↗

PubMed1993

Synthetic retinoid fenretinide is effective against a human ovarian carcinoma xenograft and potentiates cisplatin activity.

Fenretinide or N-(4-hydroxyphenyl) retinamide (4HPR) is a synthetic retinoid currently being tested clinically, which can inhibit the development and the growth of breast and prostate cancers in rodents. The efficacy of 4HPR alone and in combination with cisplatin was tested against the human ovarian carcinoma IGROV-1 xenograft i.p. Administration p.o. of 4HPR was not effective, whereas intracavitary treatment significantly increased the survival time of treated mice. It also enhanced the antitumor activity of cisplatin. These findings suggest that 4HPR may be an active agent against epithelial ovarian tumors.

Adenocarcinoma↗

PubMed1993

Retinoids: in vitro interaction with retinol-binding protein and influence on plasma retinol.

Studies have been conducted to investigate the structure-function relationships of retinoids in their in vitro interaction with plasma retinol-binding protein (RBP) and in their influence on plasma retinol concentration. Two classes of retinoids, one bearing modifications in the area of the retinol hydroxyl end group (fenretinide, N-(ethyl) retinamide, all-trans, and 13-cis retinoic acid) and the other one also bearing modifications in the area of the cyclohexene ring (etretinate, acitretin, and arotinoid Ro 13-7410), were investigated. Whereas substantial modifications of the retinol hydroxyl group do not prevent the binding to RBP, an intact trimethylcyclohexenyl group seems to be crucial for binding. Both classes of retinoids, administered orally at equimolar doses, reduce plasma retinol concentration in rats but with different kinetics. A marked lowering of plasma retinol occurs early (within 5 h) after administration of retinoids that interact with RBP in vitro, whereas it occurs at later times (24 h) after retinoids that do not interact with RBP. The concentrations of both classes of retinoids found in plasma do not account for the temporal difference in this effect. The early reduction of plasma retinol might be the consequence of in vivo specific binding of retinoids to RBP, as suggested by the in vitro results. The late reduction observed for retinoids lacking in vitro affinity for RBP is due to other mechanisms or to metabolism to retinoids binding to RBP.

Animals↗

PubMed1992

Postsurgical adjuvant chemoimmunotherapy with recombinant interleukin-2 and 1,3-bis-(2-chloroethyl)-1-nitrosourea on spontaneous metastases of a non-immunogenic murine tumour.

The efficacy of the association of recombinant interleukin-2 (rIL-2) with chemotherapy has been investigated on an experimental model representative of clinical tumours, i.e. on post-surgical spontaneous metastases of a non-immunogenic tumour. We used the M5076 ovarian reticulum cell sarcoma, which metastasizes to the liver after intra-footpad implantation. Such a tumour appeared to be non-immunogenic by a variety of commonly used in vivo assays. Four clinically widely employed drugs, i.e. doxorubicin, cis-diamminedichloroplatinum II, cyclophosphamide and 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), were tested and BCNU proved to be the most effective one when administered as single injection at the maximum tolerated dose (33 mg/kg i.p.) 1 day after tumour excision. When moderate doses of rIL-2 (6 x 10(5) IU in three injections per day for 5 days) were administered at three different intervals after BCNU, namely before the nadir of white blood cells (1 day after BCNU), at the nadir (3 days after BCNU) or at recovery (6 days after BCNU), no increase in BCNU antitumour activity was observed. The same results were obtained by administering rIL-2 for 5 days before BCNU. Higher doses of rIL-2 (1.2 x 10(6) IU in three injections per day for 5 days), which were always well tolerated in sham-excised non-tumour-bearing mice, proved lethal in two out of four experiments in tumour-bearing animals. In the two experiments in which no lethality was observed, the administration of high doses of rIL-2 1 or 6 days after BCNU significantly increased the antitumour activity of BCNU alone. rIL-2 alone was not active even when administered at high doses. These results indicate that high but not moderate doses of rIL-2 may increase the activity of BCNU against a non-immunogenic tumour. Moreover, they suggest that rIL-2 tolerability is reduced in tumour-bearing mice.

Animals↗

PubMed1988

Effect of verapamil on doxorubicin activity and pharmacokinetics in mice bearing resistant and sensitive solid tumors.

The effect of the combined administration of verapamil (i.p. twice daily) and doxorubicin (i.v. once weekly) was tested in mice bearing the following: (a) a tumor with induced resistance to doxorubicin (B16VDXR melanoma line); (b) a tumor inherently resistant (MXT mammary carcinoma); and (c) four solid tumors sensitive to doxorubicin (B16 melanoma, B16V melanoma line, M5076 reticulum cell sarcoma, and Lewis lung carcinoma). Verapamil, given according to this treatment schedule, reached peak plasma concentrations of 3 microM. Such treatment did not enhance doxorubicin activity on either inherently or induced resistant tumors, whereas it significantly enhanced doxorubicin growth inhibition in all the sensitive tumors except the Lewis lung carcinoma. Doxorubicin pharmacokinetics after administration of the drug alone and in combination with verapamil was analyzed after the first and repeated treatments in animals bearing B16 melanoma or its resistant subline B16VDXR. The resistance of the B16VDXR line was associated with the ability of the tumor to retain less doxorubicin (AUC = 83 micrograms h/g) than the sensitive tumor B16 (AUC = 204 micrograms h/g) in spite of similar initial levels. The potentiating effect of doxorubicin activity by verapamil in B16 melanoma was not associated with increased doxorubicin levels or retention in the tumor, nor were differences in doxorubicin levels or retention found in the B16VDXR line. The combined treatment did not modify doxorubicin pharmacokinetics in plasma, heart, or spleen. These studies suggest that verapamil in vivo is ineffective in potentiating doxorubicin activity in tumors against which doxorubicin is inactive, that sensitive tumors are heterogeneous in their sensitivity to modulation by verapamil, and that this effect is not associated with modification of doxorubicin pharmacokinetics.

Animals↗

PubMed1988

Verapamil potentiation of doxorubicin resistance development in B16 melanoma cells both in vitro and in vivo.

The effect of the combined administration of doxorubicin (DX) and verapamil (VRP) on the induction of DX resistance of B16 melanoma cells, was investigated both in vitro and in vivo. Cells grown in the presence of increasing concentrations of DX and of 1 microM VRP, tested at several passages, were more resistant than cells grown with DX alone. The treatment of B16 melanoma bearing mice with the maximal tolerated dose of DX (12 mg kg-1 i.v.) and of VRP (25 mg kg-1 i.p.) selected a line (B16-DX. VRP) completely resistant to DX after 17 transplants, while treatment with DX alone selected a DX resistant line after 27 transplants. Lung metastases were significantly lower in the B16-DX. VRP line compared to the original B16 melanoma. The results suggest that the association of VRP with DX increases the rate of resistance development to DX.

Animals↗