Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0007097 (carcinoma)
 152,788 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

SDZ 280-446 is a semi-synthetic derivative of a natural cyclic peptolide. Its ability to sensitise in vitro tumour cells whose resistance is due to P-glycoprotein-mediated anticancer-drug efflux was shown using four different pairs of parental drug-sensitive (Par-) and multidrug-resistant (MDR-) cell lines, from three different species (mouse, human, Chinese hamster) representing four different cell lineages (monocytic leukaemia, nasopharyngeal epithelial carcinoma, colon epithelial carcinoma, ovary fibroblastoid carcinoma), and using four different drug classes (colchicine, vincristine, daunomycin/doxorubicin and etoposide). By measuring its capacity to restore normal drug sensitivity of MDR-cells in culture in vitro, it appeared that SDZ 280-446 belongs to the same class of very potent chemosensitisers as the cyclosporin derivative SDZ PSC 833: both are about one order of magnitude more active than cyclosporin A (CsA), which is itself about one order of magnitude more active than other known chemosensitisers (including verapamil, quinidine and amiodarone which have already entered clinical trials in MDR reversal). Low concentrations of SDZ 280-446 could also restore cellular daunomycin retention in MDR-P388 cells to the levels found in the Par-P388 cells. SDZ 280-446 was also effective as a chemosensitiser when given orally in vivo. In a syngeneic mouse model, combined therapy with vinca alkaloids given i.p. and SDZ 280-446 given per os for 5 consecutive days significantly prolonged the survival of MDR-P388 tumour-bearing mice, when compared with mice receiving vinca alkaloids alone. Another protocol, using three cycles of i.p. doxorubicin at 4 day intervals, could also not increase MDR-P388 tumour-bearing mouse survival unless the mice received SDZ 280-446 orally 4 h before each doxorubicin injection. Though only very few combined therapy treatment protocols have been tested so far, clear increases in survival time of MDR-tumour-bearing mice were regularly obtained, leaving hope for major improvement of the therapy using other dosing schedules.
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PMID:SDZ 280-446, a novel semi-synthetic cyclopeptolide: in vitro and in vivo circumvention of the P-glycoprotein-mediated tumour cell multidrug resistance. 134 65

In many cell systems, resistance to cytotoxic drugs is acquired by the amplification and/or overexpression of the multidrug resistance (mdr) gene, which codes for the glycoprotein, p170 (P-glycoprotein). Moreover, in a variety of malignant tumours there is increasing evidence of the relationship between the DNA ploidy pattern of patients and their prognosis. In this study we aimed to evaluate these two potential indicators of constitutive drug resistance in human colorectal tumours. We employed a method to quantify simultaneously, on a per cell basis, mdr gene expression (using the C219 monoclonal antibody for P-glycoprotein) and nuclear DNA content with high-resolution bivariate flow cytometry. The study was performed on a human colon-carcinoma-derived cell line (LoVo) and its doxorubicin-resistant variant (LoVo/Dx) and on tumour samples and adjacent normal mucosa from 35 untreated patients with colon cancer. The P-glycoprotein was found in both LoVo and LoVo/Dx cells with levels slightly lower in the parental than in the resistant subline (P, NS). A multi-drug-resistant specific probe for mRNA expression and Western blot assay confirmed the specificity of p170 expression. All of the colon cancer with unimodal diploid DNA distribution and all the normal colonic mucosa samples showed P-glycoprotein expression, without a statistically significant difference in median values between tumours and normal samples. Tumours with bimodal DNA distribution showed median values of P-glycoprotein expression of their hyperdiploid cell clones significantly higher than those of their diploid clones and of the tumours with unimodal DNA distribution (P less than 0.005). Our results show the feasibility of bivariate flow-cytometric analysis of P-glycoprotein expression and DNA content on clinical material and support the hypothesis that the MDR phenotype and DNA ploidy together may influence the biological behaviour of colon cancer in vivo.
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PMID:Flow cytometric analysis of multidrug-resistance-associated antigen (P-glycoprotein) and DNA ploidy in human colon cancer. 135 83

A series of MDR cell lines with various levels of P-glycoprotein have been established from a human colorectal carcinoma cell line, HCT-15, by stepwise exposure to adriamycin. The relative drug resistance of these cell lines correlated directly with both MDR1 mRNA levels and P-glycoprotein expression levels. Intracellular accumulation of adriamycin decreased inversely to their resistance. Drug sensitivities of these lines were reversed using verapamil. Since these cell lines are transplantable to nude mice, they may provide a useful animal model of MDR solid tumors for therapeutic experiments.
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PMID:Establishment of multidrug resistant human colorectal carcinoma HCT-15 cell lines and their properties. 167 19

It has previously been shown that B-859-35 ((-)-3-methyl-5- 3-(4,4-diphenyl-l-piperidinyl)-propyl-l,4-dihydro- 2,6-dimethyl-4-(3-nitrophenyl)-pyridine-3,5-dicarboxylate-hydrochloride) exerts a selective carcinostatic effect on some tumors. In order to evaluate whether the anti-cancer activity of B-859-35 can be modulated, we combined the new drug with several established anti-tumor drugs. A combination of B-859-35 with VP-16 (etoposide) in MDR(multi-drug-resistant-gene)-expressing Walker rat carcinoma cells shows synergism. A combination of B-859-35 with doxorubicin results in stronger synergism than verapamil/doxorubicin, especially at low concentrations of B-859-35. The resistance of mdrl(human multi-drug-resistance-gene)-expressing human HeLa KB-8-5 cells to doxorubicin can be reversed with non-toxic or weakly toxic concentrations of B-859-35 to the sensitivity of the parent KB-3-l cells. The finding that an anti-tumor drug is able to reverse multi-drug resistance makes B-859-35 an interesting drug for cancer treatment.
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PMID:B-859-35, a new drug with anti-tumor activity reverses multi-drug resistance. 184 22

Following EMS mutagenesis, three estramustine (EM) resistant DU 145 human prostatic carcinoma cell lines were clonally selected by exposure to incrementally increasing concentrations of the drug. Although only low levels of resistance (approximately 3-fold) were attainable, this resistance was stable in the absence of continuous drug exposure. These EM-resistant clones (EMR 4,9,12) did not exhibit cross resistance to vinblastine, taxol, or adriamycin, and had collateral sensitivity to cytochalasin B. None of the lines had elevated expression of P-glycoprotein mRNA or glutathione S-transferase activity, suggesting a phenotype distinct from the classic multi-drug resistance phenotype. This conclusion was supported further by the observation that two MDR cell lines (FLC mouse erythroleukaemic and SKOV3 human ovarian carcinoma cells) showed sensitivity to EM. Fluorescent activated cell sorting analysis of the effects of EM on cell cycle traverse revealed that at EM concentrations up to 20 microM an increasing percentage of wild type cells were blocked in G2/M; no such effect occurred in EMR lines. Differential interference contrast microscopy was employed to study EM's effect on mitosis. EMR lines were able to form functional, albeit smaller, spindles at EM concentrations that resulted in chromosomal disorganisation and inhibition of mitotic progression in wild type cells. EMR lines were able to progress through mitosis and cytokinesis at the same rate as untreated cells. Tritiated EM was used to evaluate potential drug uptake/efflux mutations in ERM clones. EMR 4 and 9 incorporate less EM than wild type cells; however, they have significantly decreased cellular volumes. The initial efflux rate constants for EMR clones were greater than for wild type cells. Within 5 min greater than 70% of the drug was lost from resistant cells compared to a 50% loss by the wild type. Although the specific mechanisms of resistance have yet to be defined, the lack of collateral resistance to other MDR/anti-microtubule agents could serve as the basis for the clinical use of EM in combination chemotherapy.
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PMID:Resistance to the antimitotic drug estramustine is distinct from the multidrug resistant phenotype. 189 55

The resistance of malignant tumors to chemotherapy is often associated with overexpression of the multidrug resistance gene MDR. Its gene product, P-glycoprotein, acts as a drug efflux pump for chemotherapeutic agents. The authors studied MDR expression in 28 adenocarcinomas arising in Barrett's esophagus (EAs) using a monoclonal antibody directed against this gene product. The results were compared with MDR expression in 27 gastric adenocarcinomas (GAs). P-glycoprotein was detected in both tumor and normal mucosa in 7 of 27 GAs and in 6 of 10 EAs that were resected without prior chemotherapy. Chemotherapy was given before surgical resection in 18 of the EAs studied. Five patients had a partial response to chemotherapy, and one had a complete eradication of his carcinoma; all of these tumors were negative for P-glycoprotein. Of 12 patients without chemotherapy response, 6 had tumors that expressed P-glycoprotein. The authors conclude that P-glycoprotein is present in EAs and GAs before exposure to chemotherapy. The presence of P-glycoprotein in tumors usually correlates with its presence in the adjacent mucosa. Its presence in tumor cells may be an indicator of lack of sensitivity to chemotherapy.
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PMID:Expression of a multidrug resistance gene in esophageal adenocarcinoma. Correlation with response to chemotherapy and comparison with gastric adenocarcinoma. 239 10

1. APP is activated by adenosine kinase to its 5'-phosphate (APP-MP). 2. APP-MP inhibits PRPP synthetase, and depletes cellular PRPP and purine and pyrimidine nucleotides. 3. APP inhibits synthesis of DNA and RNA, and blocks cells in G1 phase of the cell cycle. 4. APP retains full activity against MDR cells. 5. APP is equally active against quiescent and proliferating CHO cells. 6. APP has only weak activity against L1210 leukemia in vivo, but has substantial activity against mammary carcinoma 16/c. 7. In vitro, APP has a relatively high ratio of solid tumor: leukemia activity.
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PMID:Biochemical pharmacology and antitumor properties of 4-amino-8-[beta-D-ribofuranosylamino]pyrimido-[5,4-d]pyrimidine. 256 Mar 25

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

We have investigated the relationship between protein kinase C (PKC), levels of resistance and drug used for selection in a series of human KB carcinoma cell lines by comparing protein kinase C activity and PKC alpha, beta I, beta II, gamma, delta, epsilon, and zeta subspecies protein expression. PKC alpha protein expression was increased by 600% and 375% in KB-A1 and KB-C1 lines respectively over the parent KB-3-1 line; only KB-A1 cells showed increased PKC delta expression. Expression of other PKC subspecies was equal to that of KB-3-1 cells. There was considerable variation between the different KB cell lines in total cytosolic PKC activity, the KB-A1 and KB-C1 lines showing 400% and 350% increases respectively, KB-V1 and KB-8-5-11 about 180%, and KB-8-5 no increase relative to the parent KB-3-1 line. For calcium-independent PKC activity, the KB-C1 and KB-A1 lines only were increased over the KB-3-1 line. Immunoprecipitation with antisera to PKC subspecies confirmed that the increase in KB-A1 cytosolic total PKC activity was due largely to PKC alpha and partially to PKC delta. Membrane-associated PKC activity was increased by 500% and 350% in KB-A1 and KB-C1 lines respectively, by 250% and 270% in KB-V1 and KB-8-5-11, and not increased in KB-8-5 cells relative to the KB-3-1 cells. For KB-C1, KB-8-5-11, and KB-8-5 lines, which show decreasing resistance to colchicine, our results suggest a correlation between PKC and multidrug resistance in cells selected for resistance to this drug. There is no correlation between PKC and multidrug resistance for cells selected in different drugs. Our study therefore suggests that specific PKC subspecies are associated with the MDR phenotype of some KB cell lines, but that the extent of PKC involvement depends on the type of drug used for selection and its concentration.
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PMID:Changes in protein kinase C subspecies protein expression and activity in a series of multidrug-resistant human KB carcinoma cell lines. 770 29

Tamoxifen (TAM), a widely used agent in the hormonal therapy of breast cancer, is also an antagonist of P-glycoprotein (P-gp), a cell surface protein which confers drug resistance to cells. Here we report that in an estrogen receptor-deficient multidrug-resistant subline of MCF-7 human breast carcinoma cells (MCF-7/MDR), but not in the parent drug-sensitive cells (MCF-7/WT), clinically relevant concentrations (1-5 microM) of TAM inhibited the uptake and phosphorylation of ethanolamine and choline. These inhibitory effects resulted in decreased synthesis of the corresponding phospholipids. In view of the known dependence of P-gp function on phosphatidylethanolamine (PtdEtn), inhibition of PtdEtn synthesis may represent an additional mechanism by which TAM inhibits P-gp-mediated drug efflux.
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PMID:Tamoxifen inhibits uptake and metabolism of ethanolamine and choline in multidrug-resistant, but not in drug-sensitive, MCF-7 human breast carcinoma cells. 787 22


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