Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 16 de 16
Filter
Add more filters










Publication year range
1.
Nucleic Acids Res ; 29(6): 1300-7, 2001 Mar 15.
Article in English | MEDLINE | ID: mdl-11238996

ABSTRACT

We have previously isolated the hpttg proto-oncogene, which is expressed in normal tissues containing proliferating cells and in several kinds of tumors. In fact, expression of hPTTG correlates with cell proliferation in a cell cycle-dependent manner. Recently it was reported that PTTG is a vertebrate analog of the yeast securins Pds1 and Cut2, which are involved in sister chromatid separation. Here we show that hPTTG binds to Ku, the regulatory subunit of the DNA-dependent protein kinase (DNA-PK). hPTTG and Ku associate both in vitro and in vivo and the DNA-PK catalytic subunit phosphorylates hPTTG in vitro. Furthermore, DNA double-strand breaks prevent hPTTG-Ku association and disrupt the hPTTG-Ku complexes, indicating that genome damaging events, which result in the induction of pathways that activate DNA repair mechanisms and halt cell cycle progression, might inhibit hPTTG-Ku interaction in vivo. We propose that hPTTG might connect DNA damage-response pathways with sister chromatid separation, delaying the onset of mitosis while DNA repair occurs.


Subject(s)
Antigens, Nuclear , DNA Helicases , DNA-Binding Proteins/metabolism , Neoplasm Proteins/metabolism , Nuclear Proteins/metabolism , Protein Serine-Threonine Kinases/metabolism , Saccharomyces cerevisiae Proteins , Animals , COS Cells , Cell Differentiation , Cell-Free System/chemistry , Cell-Free System/metabolism , DNA Damage , DNA-Activated Protein Kinase , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/genetics , Dimerization , HL-60 Cells , HeLa Cells , Humans , Jurkat Cells , Ku Autoantigen , Neoplasm Proteins/genetics , Nuclear Proteins/chemistry , Nuclear Proteins/genetics , Phosphorylation , Protein Binding , Protein Serine-Threonine Kinases/genetics , Protein Subunits , Proto-Oncogene Mas , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Saccharomyces cerevisiae/genetics , Securin , Substrate Specificity , Two-Hybrid System Techniques
2.
Biochem Biophys Res Commun ; 276(1): 362-70, 2000 Sep 16.
Article in English | MEDLINE | ID: mdl-11006130

ABSTRACT

The mechanism(s) by which HIV-1 infection contributes to depletion of CD4(+) T cell is not well understood. In this report, we investigated whether a recently identified isoform of growth factor receptor bound protein (Grb2), named Grb3-3, a signaling molecule that is associated with the MAP kinase pathway and with apoptosis could be involved. We find that Grb3-3 is markedly up-regulated following HIV-1 infection of CD4(+) peripheral blood mononuclear cells undergoing apoptosis. Although IL-2 deprived CD4(+) cells also undergo apoptosis to a similar extent, Grb3-3 upregulation is not detected under these experimental conditions. Transient overexpression of Grb3-3 in Jurkat T-cells also causes apoptosis. Upon staurosporine stimulation, Grb3-3 predisposes Sup-T1 cell to apoptosis. Finally, analysis of the HIV-1 genes responsible for Grb3-3 expression demonstrates that Tat and Nef can independently induces its expression, suggesting these two earliest viral gene products of HIV-1 may share some common pathway(s) in up-regulating Grb3-3 expression.


Subject(s)
Adaptor Proteins, Signal Transducing , CD4-Positive T-Lymphocytes/metabolism , HIV Infections/immunology , HIV Infections/metabolism , HIV-1 , Protein Biosynthesis , Apoptosis/genetics , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/pathology , GRB2 Adaptor Protein , HIV Infections/genetics , HIV Infections/pathology , Humans , Proteins/genetics , Up-Regulation
3.
J Biol Chem ; 275(40): 30925-33, 2000 Oct 06.
Article in English | MEDLINE | ID: mdl-10906142

ABSTRACT

The MAPK pathway is required for T-cell activation; however, its role in modulating T-cell function following human immunodeficiency virus type 1 (HIV-1) infection is poorly understood. In this report, we investigated whether Grb3-3, an isoform of the Grb2 (growth factor receptor-bound protein-2) adaptor molecule that is associated with the MAPK pathway, could be involved. We found that Grb3-3, but not its isoform Grb2, is markedly up-regulated in CD4(+) peripheral blood mononuclear cells derived from either in vitro HIV-1-infected cultures or HIV-1-infected human subjects. Analysis of HIV-1 gene products indicated that Tat and Nef, both of which have been implicated in modulating T-cell function, can independently induce expression of Grb3-3. By using NFAT/AP-1, AP-1, or NFAT reporter assays, we found that Grb3-3 can potentiate NFAT (but not AP-1) promoter activity in Jurkat T-cells upon engagement of the T-cell receptor and CD28 co-receptor. In addition, potentiation of NFAT by Grb3-3 is substantially suppressed by MEKK1, a kinase that may play an important role in retaining NFAT in the cytoplasm, and by cyclosporin A. Finally, we also found that Grb3-3 potentiates HIV-1 long terminal (LTR) repeat promoter activity following T-cell receptor stimulation, an effect that can be largely suppressed by cyclosporin A. Taken together, this study indicates that Grb3-3 is a cellular factor that can be up-regulated by HIV-1. In addition, Grb3-3 can also function as a positive factor for T-cell activation and, in doing so, may aid in establishing an intracellular environment that can optimally support HIV-1 replication.


Subject(s)
Adaptor Proteins, Signal Transducing , DNA-Binding Proteins/metabolism , HIV-1/metabolism , MAP Kinase Kinase Kinase 1 , Nuclear Proteins , Proteins/metabolism , Transcription Factors/metabolism , Up-Regulation , Adult , Antibodies, Monoclonal/metabolism , Blotting, Western , CD28 Antigens/metabolism , CD4-Positive T-Lymphocytes/metabolism , CD4-Positive T-Lymphocytes/virology , Cell Nucleus/metabolism , Cyclosporine/pharmacology , Cytoplasm/metabolism , DNA-Binding Proteins/genetics , Female , GRB2 Adaptor Protein , Gene Products, nef/metabolism , Gene Products, tat/metabolism , HIV Infections/metabolism , Humans , Immunosuppressive Agents/pharmacology , Jurkat Cells , Leukocytes, Mononuclear/virology , Luciferases/metabolism , MAP Kinase Signaling System , Male , Middle Aged , NFATC Transcription Factors , Plasmids/metabolism , Promoter Regions, Genetic , Protein Isoforms , Protein Serine-Threonine Kinases/metabolism , Proteins/chemistry , Proteins/genetics , RNA, Messenger/metabolism , Receptors, Antigen, T-Cell/metabolism , Signal Transduction , Terminal Repeat Sequences , Time Factors , Transcription Factor AP-1/metabolism , Transcription Factors/genetics , Transfection , nef Gene Products, Human Immunodeficiency Virus , tat Gene Products, Human Immunodeficiency Virus
4.
Oncogene ; 19(3): 403-9, 2000 Jan 20.
Article in English | MEDLINE | ID: mdl-10656688

ABSTRACT

We recently isolated a cDNA for hpttg, the human homolog of rat pituitary tumor transforming gene. Now we have analysed the expression of hpttg as a function of cell proliferation. hPTTG protein level is up-regulated in rapidly proliferating cells, is down-regulated in response to serum starvation or cell confluence, and is regulated in a cell cycle-dependent manner, peaking in mitosis. In addition, we show that hPTTG is phosphorylated during mitosis. Immunodepletion and in vitro phosphorylation experiments, together with the use of a specific inhibitor, indicate that Cdc2 is the kinase that phosphorylates hPTTG. These results suggest that hpttg is induced by, and may have a role in, regulatory pathways involved in the control of cell proliferation.


Subject(s)
Neoplasm Proteins/metabolism , Oncogene Proteins/metabolism , Amino Acid Sequence , Animals , CDC2 Protein Kinase/physiology , COS Cells , Cell Cycle , Cell Division , HeLa Cells , Humans , Mitosis , Molecular Sequence Data , Phosphorylation , Proto-Oncogene Mas , Securin , src Homology Domains
5.
J Biol Chem ; 273(38): 24301-4, 1998 Sep 18.
Article in English | MEDLINE | ID: mdl-9733714

ABSTRACT

Epidermal growth factor (EGF) receptor was shown to be involved in the activation pathway of the stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK) cascade not only by EGF, but also by UV radiation or osmotic stress. This paper describes a specific interaction between the COOH-terminal SH3 domain of Grb2 and the NH2-terminal regulatory domain of MEKK1 in ER22 cells overexpressing the EGF receptor. This interaction results in the formation of a constitutive complex between Grb2 and MEKK1 in both proliferating and resting cells. EGF stimulation causes this complex to be rapidly and transiently recruited by Shc proteins. The subsequent release of the Grb2-MEKK1 complex from Shc proteins correlates with JNK activation. Transfection of the NH2-terminal regulatory domain of MEKK1 specifically inhibits EGF-dependent JNK activation indicating that Grb2 is involved in MEKK1 activation. Thus, adaptor proteins have a new role in the regulation of the SAPK/JNK cascade after EGF stimulation.


Subject(s)
Adaptor Proteins, Signal Transducing , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Epidermal Growth Factor/physiology , ErbB Receptors/physiology , Mitogen-Activated Protein Kinases , Protein Serine-Threonine Kinases/metabolism , Proteins/metabolism , Animals , Cell Line , Chloramphenicol O-Acetyltransferase/biosynthesis , Enzyme Activation , Epidermal Growth Factor/pharmacology , ErbB Receptors/genetics , GRB2 Adaptor Protein , JNK Mitogen-Activated Protein Kinases , Kinetics , Protein Biosynthesis , Protein Serine-Threonine Kinases/biosynthesis , Protein Serine-Threonine Kinases/genetics , Proteins/genetics , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/metabolism , Recombinant Proteins/biosynthesis , Transcriptional Activation , Transfection , src Homology Domains
7.
Cancer Res ; 58(6): 1170-6, 1998 Mar 15.
Article in English | MEDLINE | ID: mdl-9515802

ABSTRACT

Mutated ras genes are found in a large number of human tumors and, therefore, constitute one of the primary targets for cancer treatment. Microinjection of the neutralizing anti-Ras monoclonal antibody Y13-259 was previously reported to induce transient phenotypic reversion of ras-transformed rodent fibroblasts in vitro. We have prepared a single-chain Fv fragment (scFv) derived from Y13-259, and here, we show that intracellular expression of the scFv led to the specific inhibition of the Ras signaling pathway in Xenopus laevis oocytes and NIH3T3 fibroblasts. Moreover, neutralizing Ras with the scFv specifically promoted apoptosis in vitro in human cancer cells but not in untransformed cells. As a step toward cancer gene therapy, we finally demonstrated that intratumor transduction of HCT116 colon carcinoma cells with the anti-Ras scFv using an adenoviral vector elicited sustained tumor regression in nude mice.


Subject(s)
Immunoglobulin Fragments/administration & dosage , Neoplasms, Experimental/therapy , Proto-Oncogene Proteins p21(ras)/antagonists & inhibitors , Animals , Antibodies, Monoclonal/administration & dosage , Apoptosis , Genes, p53 , Genes, ras , Humans , Immunotherapy , Mice , Mice, Nude , Microinjections , Proto-Oncogene Proteins p21(ras)/immunology , Signal Transduction , Transcriptional Activation , Tumor Cells, Cultured , Xenopus laevis
8.
Cell Signal ; 9(2): 153-8, 1997 Feb.
Article in English | MEDLINE | ID: mdl-9113414

ABSTRACT

One attractive candidate for a Ras effector protein, other than the Raf kinases, is Ras-GAP. Indeed, recent literature suggests that besides the Raf/MAP kinase cascade, additional pathways must be stimulated to elicit a full biological response to Ras. Ras binds the COOH terminal domain of Ras-GAP, while the NH2 terminal domain appears to be essential for triggering downstream signals. Since Ras-GAP itself has no obvious enzymatic function that might explain a role in processes associated with proliferation, differentiation or apoptosis, candidates for downstream Ras-GAP effectors that fulfill this role remain to be identified. The newly found GAP-SH3 domain Binding Protein (G3BP) may be one of these. This review will briefly overview the candidates Ras effectors and discuss the results that position Ras-GAP as a critical effector downstream of Ras.


Subject(s)
Proteins/metabolism , Signal Transduction/physiology , ras Proteins/metabolism , Animals , GTPase-Activating Proteins , Humans , ras GTPase-Activating Proteins
9.
Science ; 264(5161): 971-4, 1994 May 13.
Article in English | MEDLINE | ID: mdl-8178156

ABSTRACT

Growth factor receptor-bound protein 2 (Grb2) links tyrosine-phosphorylated proteins to a guanine nucleotide releasing factor of the son of sevenless (Sos) class by attaching to the former by its Src homology 2 (SH2) moiety and to the latter by its SH3 domains. An isoform of grb2 complementary DNA (cDNA) was cloned that has a deletion in the SH2 domain. The protein encoded by this cDNA, Grb3-3, did not bind to phosphorylated epidermal growth factor receptor (EGFR) but retained functional SH3 domains and inhibited EGF-induced transactivation of a Ras-responsive element. The messenger RNA encoding Grb3-3 was expressed in high amounts in the thymus of rats at an age when massive negative selection of thymocytes occurs. Microinjection of Grb3-3 into Swiss 3T3 fibroblasts induced apoptosis. These findings indicate that Grb3-3, by acting as a dominant negative protein over Grb2 and by suppressing proliferative signals, may trigger active programmed cell death.


Subject(s)
Adaptor Proteins, Signal Transducing , Apoptosis , ErbB Receptors/metabolism , Proteins/genetics , 3T3 Cells , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , Epidermal Growth Factor/pharmacology , GRB2 Adaptor Protein , Humans , Mice , Molecular Sequence Data , Proteins/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , T-Lymphocytes/cytology , Thymus Gland/metabolism , Transcriptional Activation/drug effects , Transfection
11.
Oncogene ; 8(6): 1477-85, 1993 Jun.
Article in English | MEDLINE | ID: mdl-7684828

ABSTRACT

A critical step in the activation of cellular Ras is the release of bound GDP. Oligonucleotide primers derived from a mouse cDNA sequence homologous to the Saccharomyces cerevisiae CDC25 gene product were used to screen a human brain cDNA library. The cloning led to the isolation of a 2.8-kb cDNA predicted to encode a protein of 488 amino acids. This protein was produced in Escherichia coli as a glutathione S-transferase fusion protein and functioned in vitro as a specific guanine nucleotide-releasing factor. Polyclonal antibodies raised against the last 281 amino acids of the protein allowed a protein in the molecular weight range of 55 kDa to be identified in human cortex homogenates. Analysis by Northern blotting led to the identification of a 5.5-kb mRNA in brain poly(A)+ RNA. The functionality of the encoded protein was evaluated after expression in different cells: (i) in Saccharomyces cerevisiae the effects of the cdc25.5 and RAS2 Ala-22 mutations were reversed; (ii) in chinese hamster ovary cells, a RAS-responsive element was transactivated as demonstrated by the expression of a CAT reporter gene under the control of the polyomavirus enhancer. Finally, in situ hybridization on of human chromosomes revealed a localization on band 15q2.4.


Subject(s)
Brain/metabolism , Cell Cycle Proteins , Cerebral Cortex/metabolism , Chromosomes, Human, Pair 15 , GTP-Binding Proteins/genetics , Proteins/genetics , Proteins/metabolism , Proto-Oncogene Proteins p21(ras)/metabolism , ras-GRF1 , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , Blotting, Western , Chromosome Banding , Chromosome Mapping , Cloning, Molecular , Fungal Proteins/genetics , GTP-Binding Proteins/metabolism , Glutathione Transferase/genetics , Glutathione Transferase/metabolism , Guanine Nucleotide Exchange Factors , Humans , Kinetics , Mice , Molecular Sequence Data , Oligodeoxyribonucleotides , Open Reading Frames , Poly A/genetics , Poly A/metabolism , RNA/genetics , RNA/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Recombinant Fusion Proteins/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins , Sequence Homology, Nucleic Acid , ras Guanine Nucleotide Exchange Factors
12.
J Biol Chem ; 268(15): 11113-8, 1993 May 25.
Article in English | MEDLINE | ID: mdl-8388382

ABSTRACT

The best characterized yeast guanine nucleotide releasing factor is CDC25, which acts on RAS and thereby stimulates cAMP production in Saccharomyces cerevisiae. In order to determine if CDC25 could be a specific GDP-GTP releasing factor for the mammalian proteins Ha-ras, Ki-ras, and N-ras, its functions were studied both in vitro and in NIH3T3 cells. The 561 amino acid composing the C-terminal domain of CDC25 (CDC25 C-domain) released guanine nucleotides (both GDP and GTP) from Ha-, Ki-, and N-ras but not from Rap1A, Rab5, and Rab11. CDC25 acted on oncogenically activated Ha-ras even if the last 23 amino acids (167-189) of the Ras proteins were not present. CDC25 transformed NIH3T3 cells; its transforming capacity was enhanced by overexpression of wild-type Ha-ras. CDC25 C-domain probably exerts its effects through the activation of cellular Ras proteins. These data suggest that the CDC25 C-domain can function as an upstream activator of Ras proteins in a heterologous system and therefore could be a useful tool to study the regulation of Ras activation by growth factor receptors.


Subject(s)
Cell Cycle Proteins , Cell Transformation, Neoplastic , Fungal Proteins/metabolism , GTP-Binding Proteins/metabolism , Guanosine Diphosphate/metabolism , Proto-Oncogene Proteins p21(ras)/metabolism , Saccharomyces cerevisiae/metabolism , ras-GRF1 , 3T3 Cells , Animals , Enhancer Elements, Genetic , Escherichia coli/genetics , Fungal Proteins/genetics , GTP-Binding Proteins/genetics , Guanosine Triphosphate/metabolism , Kinetics , Mice , Mice, Nude , Neoplasm Transplantation , Plasmids , Polyomavirus/genetics , Recombinant Proteins/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins , Transfection/methods
13.
Mol Cell Biol ; 13(1): 39-43, 1993 Jan.
Article in English | MEDLINE | ID: mdl-8380225

ABSTRACT

The carboxy-terminal part of the Saccharomyces cerevisiae SDC25 gene product (SDC25 C domain) can elicit activation of mammalian Ras proteins. Specifically, SDC25 C domain functions as an exchange factor for cellular Ras proteins in CHO cells. In this study, we used the dominant inhibitory Ha-Ras Asn-17 mutant and SDC25 C domain to further investigate the interaction between cellular Ras proteins and their putative endogenous guanine nucleotide-releasing factors. Transcription from the polyomavirus thymidine kinase gene (Py tk) promoter is strongly inhibited by the expression of Ha-Ras Asn-17 in NIH 3T3 cells. Coexpression of SDC25 C domain overcomes the negative effect of the Ras mutant on the Py tk promoter. On the other hand, transactivation of the Ras-responsive element of the Py tk promoter induced by SDC25 C domain is lost upon coexpression of increasing amounts of Ha-Ras Asn-17. In addition, coexpression of SDC25 C domain overcomes the inhibition of proliferation of NIH 3T3 cells caused by Ha-Ras Asn-17. These results are consistent with the idea that the Ha-Ras Asn-17 mutant functions by titrating an upstream activator of cellular Ras proteins.


Subject(s)
Fungal Proteins/metabolism , GTP-Binding Proteins/metabolism , Gene Expression Regulation , Proto-Oncogene Proteins p21(ras)/metabolism , 3T3 Cells , Animals , Cell Division , Enhancer Elements, Genetic , Genes, Dominant , Genes, ras , Guanine Nucleotides/metabolism , Mice , Polyomavirus/genetics , Recombinant Proteins/metabolism , Saccharomyces cerevisiae/genetics , Structure-Activity Relationship , Transcription, Genetic , Transfection , rap GTP-Binding Proteins
14.
Oncogene ; 8(1): 215-8, 1993 Jan.
Article in English | MEDLINE | ID: mdl-7999142

ABSTRACT

Ras proteins in mammalian cells cycle between a GTP-bound 'on' state and a GDP-bound 'off' state. Activation of Ras p21 results from the dissociation of tightly bound GDP and the exchange of bound GDP for GTP. A guanine nucleotide exchange factor is required for this activation. Activation promotes interaction with effector molecules and allows the signal to be transduced. In Saccharomyces cerevisiae, the function of guanine nucleotide exchange has been ascribed to the product of the CDC25 gene. The C-terminus domain of SDC25, a homologue of CDC25, can substitute for the CDC25 protein in yeast. We have demonstrated that the SDC25 C-terminus domain promotes GTP binding to Ras p21 in CHO cells. In the present study, we found that the stable expression of the SDC25 C-terminus domain induced transformation of NIH3T3 cells. Ras proteins in these tumorigenic cells were GTP bound. In addition, the coexpression of wild-type Ha-Ras protein with the SDC25 C-terminus was found to enhance the tumorigenic properties of the NIH3T3 cells. These results imply that, in subsets of human tumours, cellular Ras p21 might be found in its GTP-bound active form as a consequence of an oncogenic activation of a mammalian Ras guanine nucleotide exchange factor.


Subject(s)
Cell Transformation, Neoplastic , Fungal Proteins/toxicity , Proto-Oncogene Proteins/toxicity , Saccharomyces cerevisiae/genetics , 3T3 Cells , Amino Acid Sequence , Animals , Fungal Proteins/genetics , GTP-Binding Proteins/genetics , Gene Expression Regulation , Genes, ras , Guanosine Triphosphate/metabolism , Mice , Molecular Sequence Data , Proto-Oncogene Proteins p21(ras)/metabolism , rap GTP-Binding Proteins
15.
Science ; 256(5058): 825-7, 1992 May 08.
Article in English | MEDLINE | ID: mdl-1317056

ABSTRACT

Controversy exists as to whether the interaction of a guanosine triphosphatase activating protein (GAP) with Ras proteins functions both to initiate and to terminate Ras-dependent signaling events or only to terminate them. GAP-C, a carboxyl-terminal fragment of GAP that is sufficient to stimulate GTPase activity, inhibited the stimulation of transcription produced by some oncoproteins (v-Src, polyoma middle T, wild-type Ras, and oncogenic Ras) but not that produced by v-Mos. Wild-type GAP did not affect transcription induced by oncogenic Ras but reversed the inhibitory effect of GAP-C on transcription induced by oncogenic Ras. These results indicate that GAP is a negative regulator of wild-type Ras and elicits a downstream signal by interacting with Ras-GTP (guanosine triphosphate).


Subject(s)
Cell Cycle Proteins , Cell Transformation, Neoplastic , Enhancer Elements, Genetic , Genes, ras , Polyomavirus/genetics , Proteins/metabolism , Transcriptional Activation , ras-GRF1 , 3T3 Cells , Animals , Antigens, Polyomavirus Transforming/genetics , CHO Cells , Chloramphenicol O-Acetyltransferase/genetics , Chloramphenicol O-Acetyltransferase/metabolism , Cricetinae , Fungal Proteins/genetics , Fungal Proteins/metabolism , GTPase-Activating Proteins , Humans , Mice , Oncogene Proteins v-mos , Oncogenes , Promoter Regions, Genetic , Protein-Tyrosine Kinases/genetics , Retroviridae Proteins, Oncogenic/genetics , Signal Transduction , Simian virus 40/genetics , Transcription, Genetic , Transfection , ras GTPase-Activating Proteins
16.
Anticancer Drug Des ; 5(4): 319-35, 1990 Nov.
Article in English | MEDLINE | ID: mdl-1981310

ABSTRACT

The MDR P-glycoprotein has been described as a major factor of multidrug resistance. This transmembrane glycoprotein acts like an energy dependent efflux pump which possesses a broad specificity. It seems to be acting as a pump requiring drug fixation prior to extrusion. With the aim of investigating which parameters influence the recognition of drugs by the MDR system, we have determined the toxicities of different drugs on human and murine sensitive and resistant cell lines. For this purpose we have isolated and characterized a human adriamycin-resistant cell line, CEM/Adr, which presents an MDR phenotype. The tested drugs were ellipticine and olivacine derivatives which differ through discrete lateral chain substitutions. The influence of lateral chain lipophilicity and nitrogen quaternarization on drug recognition was studied. Small modifications in the chemical structure of the drugs have induced large changes in their toxicities and in the cross-resistance levels of the MDR cells to the tested compounds. The cross-resistances of the murine and human cells to the various compounds were strikingly different. The validity of murine screening models in the selection of anti-tumor drugs for human therapy must therefore be questioned.


Subject(s)
Antineoplastic Agents, Phytogenic/pharmacology , Ellipticines/pharmacology , Leukemia P388/drug therapy , ATP Binding Cassette Transporter, Subfamily B, Member 1 , Animals , Cell Survival/drug effects , Doxorubicin/pharmacology , Drug Resistance/genetics , Drug Screening Assays, Antitumor/methods , Gene Amplification , Humans , Leukemia P388/genetics , Leukemia P388/pathology , Lipid Metabolism , Membrane Glycoproteins/metabolism , Mice , Phenotype , Solubility , Structure-Activity Relationship , Tumor Cells, Cultured
SELECTION OF CITATIONS
SEARCH DETAIL
...