Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Melanoma cells often display a multidrug-resistant phenotype, but the mechanisms involved are largely unknown. We have studied here the recently identified transport-associated proteins, MRP and LRP, and the well-known drug resistance marker P-glycoprotein using a panel of 16 human melanoma cell lines and 71 benign and malignant melanocytic tissue samples. By flow cytometry and immunohistochemistry, expression of P-glycoprotein was not detectable on the protein level in the 10 cell lines analyzed, although by reverse transcriptase polymerase chain reaction, MDR-1 gene expression was demonstrated in 2 of 10 cell lines. In addition, immunohistology revealed P-glycoprotein expression in only 1 of 71 melanocytic lesions. In contrast, MRP was detected in a subset of melanoma cell lines by reverse transcriptase polymerase chain reaction and immunohistology (4 of 10). LRP expression was observed in 8 of 10 melanoma cell lines by immunochemistry and in 10 of 10 by reverse transcriptase polymerase chain reaction. Furthermore, MRP was detected immunohistologically in almost 50% of primary and metastatic melanoma specimens, although no significant differences were found between metastases taken before or after chemotherapy. Expression of LRP was detected in a subset of nevi with nevus cells exhibiting up to 25% positive LRP reactivity. In 13 of 21 primary melanomas and 23 of 37 metastases, more than 25% of tumor cells were stained by the LRP-56 monoclonal antibody. Particularly in the group of metastases with more than 50% of LRP-positive cells, 7 of 11 of the metastases had been previously exposed to chemotherapeutic drugs. Although the expression of membrane transport proteins may explain only the chemoresistance toward lipophilic, natural compounds and not resistance against alkylating agents, the lack of P-glycoprotein expression after chemotherapeutic treatment and the significant expression of MRP and LRP in melanoma cells provide first insights into the drug-resistant phenotype in melanoma. Additional studies analyzing the role of MRP and LRP in chemoresistance of melanoma are warranted.
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PMID:Membrane transport proteins associated with drug resistance expressed in human melanoma. 749 78

Patients with metastatic breast cancer will receive 4-5 cycles of induction chemotherapy on one of the ongoing Medicine Branch protocols. Patients achieving at least a partial response, and who do not have evidence of bone marrow involvement and who do not have metastatic bone disease, will undergo PBSC and bone marrow harvest when hematologic recovery has occurred. Patients who have not achieved a PR, but who are responding to therapy, may be treated with additional cycles of therapy in an attempt to achieve a PR. Such patients will be eligible for transplant if a PR is obtained. 70% of the bone marrow and PBSC will be cryopreserved. The CD34+ subpopulation from the remaining 30% of the bone marrow and PBSC harvest will be obtained using an anti-CD34+ antibody and immunoabsorption column. The bone marrow and peripheral blood CD34 cells will be transduced with a retroviral vector expressing the human MDR-1 cDNA. Patients with positive bone scans or histologic evidence of bone marrow involvement will be excluded from the gene transfer component of the protocol. The MDR-1 transduced CD34 cells will be reinfused along with the non-transduced bone marrow and PBSC into patients following high dose ICE chemotherapy. Serial peripheral blood and bone marrow samples will be obtained to study hematopoietic reconstitution with MDR-1 transduced cells. Patients with residual or progressive disease after ABMT will be treated with taxol or vinblastine. In these relapsed patients, peripheral blood and bone marrow samples will be obtained to study whether chemotherapy amplifies the proportion of hematopoietic cells containing the MDR-1 provirus. We will monitor the nadir blood counts of each patient receiving salvage chemotherapy for evidence of myeloprotection and correlate this data with changes in the mean proviral copy number. Sites of relapsed tumor will be biopsied to test for the presence of the MDR-1 provirus.
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PMID:Retroviral mediated transfer of the human multidrug resistance gene (MDR-1) into hematopoietic stem cells during autologous transplantation after intensive chemotherapy for metastatic breast cancer. 752 2

The emergence of new cytotoxic agents and techniques for treatment of systemic disease as single modalities or in combination with irradiation and surgery will impact on the use of such agents in the management of systemic breast cancer. Metastatic breast carcinoma, unlike other solid tumors, is highly responsive to chemotherapy, response rates of 50 to 70% have been reported consistently, although there has not been a significant improvement on long-term survival of these patients in the last ten years. New therapeutic approaches include cytotoxic and hormonal agents, growth and differentiation factors, monoclonal antibodies, hematopoietic stem cell support, conquest of tumor cell resistance by MDR-modulation, genetic manipulation, identification of new targets on the tumor surface, synthesis of target-oriented designer-drugs and inhibition of tumor angiogenesis. In breast cancer the tumor growth correlates with vascularization and angiogenesis. Tumor angiogenesis is stimulated by the vascular endothelial growth factor (VEGF). Microvessel density is a significant predictor of survival among node-negative women, who are at risk for having occult metastases at presentation. These patients could then be given systemic adjuvant therapy. Animal experiments show promising inhibition of tumor growth in nude mice after application of antibodies against VEGF. Other methods of manipulation of molecular mechanisms of angiogenesis are under investigation.
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PMID:[Are there alternative forms of therapy in breast carcinoma? Status and perspectives for the treatment of metastasized breast carcinoma]. 753 44

The efficacy of mitotane in providing objective tumour responses in patients with adrenocortical carcinoma (ACC), has been recently questioned. Experience with non specific chemotherapy is limited. Tumour responses have been reported with cisplatin administered as a single agent or in combination. Other reports however failed to show benefit from cytotoxic chemotherapy. The very low number of patients included in each study, mostly of them previously treated with mitotane, may account for these controversial results. The finding that multidrug resistance mediated by MDR-1/P-glycoprotein can be reverted by mitotane provides a rational basis for exploring the use of mitotane in combination with chemotherapeutic agents. In a multicenter cooperative (SWOG) phase II study, a combination of mitotane+cisplatin appeared active in advanced ACC, with 30% response rate in 37 eligible patients. These results prompted us to evaluate the activity of a combination chemotherapy of Eto-poside, Adriamycin and Cisplatin (EAP) in association with mitotane (4 g daily per os). Up to now we treated 6 patients, obtaining 3 partial responses. Recently, new drugs as suramin and gossypol have been show to have some activity in patients with surgically unresectable ACC, suggesting the need for further investigation. In conclusion, cytotoxic drugs+mitotane and new adrenocorticolytic/cytotoxic agents, should be explored as first line treatments in patients with advanced ACC. However, due to the extreme rarity of the disease, coordinated multicenter investigations should be highly encouraged.
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PMID:Cytotoxic chemotherapy for adrenocortical carcinoma. 754 29

SDZ PSC 833 (PSC 833) is a cyclosporin A analogue that is under clinical investigation in combination with doxorubicin (Dx) or other anticancer agents as a type-1 multidrug resistance (MDR-1)-reversing agent. The present study was focused on the effects of PSC 833 on the distribution and toxicity of Dx in non-tumor-bearing CDF1 male mice. Mice were given PSC 833 i.p. at 30 min before i.v. Dx treatment. Dx levels were determined by a high-performance liquid chromatography (HPLC) assay at different times during a 72-h period following Dx treatment in the serum, heart, intestine, liver, kidney, and adrenals of mice. In all tissues, Dx area under the concentration-time curve (AUC) values were much greater in mice receiving 10 mg/kg Dx in combination with 12.5 or 25 mg/kg PSC 833 than in mice receiving Dx alone. The highest increase in Dx concentrations was found in the intestine, liver, kidney, and adrenals. Lower, albeit significant, differences were found in the heart. PSC 833 did not appear to influence either urinary or fecal Dx elimination or Dx metabolism to a great extent. Doses of PSC 833 devoid of any toxicity potentiated the acute and delayed toxicity of Dx dramatically. The mechanism responsible for this enhanced toxicity has not yet been elucidated but is likely to be related to an increased tissue retention of Dx due to inhibition of the P-glycoprotein (Pgp) pump by PSC 833, as has recently been proposed for cyclosporin A.
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PMID:Changes in doxorubicin distribution and toxicity in mice pretreated with the cyclosporin analogue SDZ PSC 833. 762 53

The use of drugs such as calcium channel blocker agents and cyclosporins as an approach to reverse the MDR phenomenon in controlled clinical trials has demonstrated the combination of these agents to markedly alter the pharmacokinetics of a number of cytotoxins associated with MDR characteristics, including doxorubicin, etoposide, paclitaxel, and vincristine. These effects are likely to be the combined effects of MDR modulators to produce decreased metabolism of the cytotoxins via the cytochrome P-450 system and decreased biliary and renal transport/excretion. It still remains to be established if the mdr1 gene is a primary drug transporter in these organs. Specificity of MDR modulators for drug metabolism and excretion requires further study, because some modulators of MDR, such as progesterone, have shown no interaction with cytotoxins (that is, doxorubicin) in clinical trials. Trials to date have indicated many modulators of MDR at doses which achieve concentrations that reverse MDR in vitro may lead to alterations of tissue function and enhance toxicity to normal tissue. In vitro data suggest many MDR modulators will enhance hematologic toxicity, beyond that predicted by the increased exposure from pharmacokinetic effects. When these interactions occur, it has been necessary to reduce the dosages of the cytotoxins in the range of 40% to 50% in most trials, if similar normal tissue toxicity--that is, myelosuppression or neuropathy--is expected. However, these empiric dose modifications in the absence of concurrent pharmacokinetic monitoring could compromise tumor exposure. Other toxicities that may be enhanced during the use of MDR modulators are nausea and vomiting, consistent with the hypothesis for a disruption of blood-brain barrier function, and augmented vinca alkaloid-associated autonomic and peripheral neuropathies. Future laboratory studies should define more effective modulators and the role of the mdr1 gene in normal tissue toxicology. These trials should focus on defining the pharmacokinetic and toxicologic interactions between the modulators and antineoplastic agents and formulate dosing guidelines for their testing in pivotal phase II and controlled phase III trials.
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PMID:MDR expression in normal tissues. Pharmacologic implications for the clinical use of P-glycoprotein inhibitors. 764 66

In the experiments, we examined the ability of a retroviral vector, pHaMASV, to encode two potential chemoprotective genes on separate transcription units. We previously described the pHaMSV vector, which includes the human MDR1 gene as a selectable marker and chemoprotective gene, plus an internal SV40 promoter for expressing a second heterologous gene along with MDR1 [M. E. Metz, D. M. Best, and S. E. Kane. Virology, 208: 634-643, 1995]. To test the ability of this vector to deliver two therapeutic genes simultaneously, the cDNA for human glutathione S-transferase pi (GST pi, the most abundant member of the glutathione S-transferase family in human tumor cells) was inserted into pHaMASV, and this plasmid was transfected into ecotropic packaging cells. The resulting pHaMASV.GST pi ecotropic retrovirus, which was produced at a titer of 2 x 10(6) colony-forming units/ml, was used to transduce NIH 3T3 cells. After initial selection in 60 ng/ml colchicine, a population of transduced cells was exposed to stepwise increasing colchicine concentrations to select for amplified expression of MDR1. As MDR1 expression increased, the expression of GST pi increased in concert, as demonstrated by Northern analysis, Western analysis, and measurement of glutathione S-transferase activity. Transduced cells growing in 1280 ng/ml colchicine had about 3-fold higher total glutathione S-transferase activity than nontransduced cells and 2.5-fold higher activity than transduced cells growing in 60 ng/ml colchicine. Northern hybridizations demonstrated a 3-5-fold increase in both the full-length retroviral message encoding MDR1 and the subgenomic mRNA encoding GST pi after amplification of resistance from 60 to 1280 ng/ml colchicine. The cytotoxic effects of several xenobiotics were evaluated in NIH 3T3 cells transfected with MDR1 (3T3.MDR) or transduced with the MDR1-GST pi retrovirus (3T3.GST640 or 3T3.GST1280) to evaluate the ability of our vector to produce a spectrum of drug resistances specific for the genes expressed. 3T3.MDR and 3T3.GST1280 cells expressing equivalent levels of MDR1 had identical levels of resistance to doxorubicin or colchicine. These results suggest that GST pi expression did not contribute to doxorubicin resistance in this model system. However, 3T3.GST640 cells were about 4-fold resistant to ethacrynic acid and 1-chloro-2,4-dinitrobenzene compared to cells expressing MDR1 alone, consistent with the ability of GST pi to conjugate both of these cytotoxins. Increases in drug resistance paralleled increases in gene-specific mRNA and recombinant protein levels in all cases.4+ chemotherapy.
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PMID:Transduction of NIH 3T3 cells with a retrovirus carrying both human MDR1 and glutathione S-transferase pi produces broad-range multidrug resistance. 766 83

Monoclonal mouse anti-Fas antibody is directed against Fas antigen, a M(r) 36,000 encoded polypeptide that belongs to the family of cell surface proteins which includes nerve growth factor receptor, tumor necrosis factor (TNF) receptors, B-cell antigen CD40, and T-cell antigens OX40. Anti-Fas antibody mimics TNF-alpha in its cytolytic activity but not in other TNF-alpha-mediated activities. Thus, we examined if anti-Fas antibody synergizes in cytotoxicity with toxins and drugs. The present studies demonstrate that anti-Fas antibody in combination with diphtheria toxin (DTX), Adriamycin, or cis-platinum results in enhanced cytotoxicity and synergy and also overrides resistance to TNF, drugs, or toxins when tested against a battery of human tumor cell lines. Synergy with anti-Fas and DTX requires that DTX is enzymatically active, since inhibitors of DTX-mediated protein synthesis inhibition resulted in loss of synergy. When the plant toxin ricin was used, there was no synergy with anti-Fas antibody but rather an additive effect. The synergy was not obtained in a TNF receptor-negative line but was achieved with other anti-Fas-resistant lines. Cell lines resistant to either Adriamycin or cis-platinum were rendered sensitive by the combination of drug and anti-Fas antibody. Further, combination treatment of anti-Fas and Adriamycin overcame resistance of the gp 170-expressing, multidrug-resistant MDR ovarian line. In all cases, cytotoxicity was augmented by pretreatment of target cells with gamma-interferon which upregulates Fas antigen expression. These results show that anti-Fas antibody can synergize in cytotoxicity with toxins and chemotherapeutic drugs, and combination treatment can reverse resistance to TNF, toxins, and/or drugs.
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PMID:Overcoming tumor necrosis factor and drug resistance of human tumor cell lines by combination treatment with anti-Fas antibody and drugs or toxins. 768 21

Drug resistance has complicated chemotherapy of neoplastic disease since the early beginnings of the field. Successful use of drug therapy requires that tumor cells be more drug-responsive than the tissue of origin. This can occur with rapidly-dividing tumors which will be highly-responsive to drugs toxic in the S-phase of the cell cycle. Another drug sensitive population will consist of neoplastic cells unable to repair drug-induced damage which can be repaired by normal host cells. Even if one of these conditions is initially found, mutational events leading to drug resistance often occur. The most thoroughly explored mode of drug resistance involves MDR (multidrug resistance), an outward transport system which limits penetration of a variety of cytotoxic agents into the cytoplasm and nucleus. MDR is expressed by many normal cell types, and attempts at MDR circumvention appear to lead to new modes of host toxicity. It appears that new directions in cancer therapy will be needed to yield responses in the common slow-growing tumors which tend to be inherently drug-resistant.
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PMID:Modes of resistance to antitumor agents. 772 32

A phase I-II clinical trial was conducted to determine the maximum-tolerated dose (MTD) of oral cyclosporine (CsA) and vinblastine in patients with metastatic renal cell cancer (RCC) as well as to estimate the response rate. Sixteen patients received a 5 mg/kg oral loading dose of CsA followed by 3 days of CsA in 4 divided daily doses escalating from 10 mg/kg per day up to 17 mg/kg per day. Vinblastine (Vbl) was administered as an intravenous bolus on the morning of the 3rd day with dose escalation from 6 to 10 mg/m2. Cycles were repeated every 4 weeks until tumor progression. Forty-nine cycles of CsA with vinblastine were administered. The maximum tolerated dose of Vbl was 10 mg/m2, with neutropenia as the dose-limiting toxicity resulting in one death. CsA could not be escalated above 17 mg/kg per day because of nausea and vomiting. Other toxicities included constipation (100%), malaise (100%), temporary increase in pain (36%), and one seizure that may have been drug-related. There were no clinically significant changes in renal function or serum bilirubin. Mean peak whole-blood CsA level at the highest CsA dose level was 919 ng/ml (range: 414-1,827) with a trough prior to Vbl injection of 451 ng/ml (range: 128-1,229). There were no tumor responses. The combination of oral CsA and Vbl is not nephrotoxic but is poorly tolerated. In most patients optimal blood levels of CsA for reversal of MDR cannot be reliably achieved, and vinblastine dose intensity must be compromised because of the significant toxicity of this regimen.
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PMID:Phase I-II study of vinblastine and oral cyclosporin A in metastatic renal cell carcinoma. 774 14


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