Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One strategy to overcome multidrug resistance in neoplasia is to inhibit the gp170 glycoprotein (relative molecular mass, 170,000) that functions as a plasma membrane, energy-dependent, drug-efflux pump. The human colon cancer cell line HT-29, which grows as an ascitic tumor in athymic NCr-nu/nu nude mice, was made multidrug resistant by infection with an MDR1 (also known as PGY1) retrovirus. Referred to as HT-29mdr1, it was used to study reversal of drug resistance in vivo by the anti-P-glycoprotein monoclonal antibody MRK-16. Flow cytometry and radioimmunoassay demonstrated a marked increase in MRK-16 reactivity on HT-29mdr1 cells as compared with its reactivity on the parental, uninfected cell line (HT-29par). The 50% inhibitory concentrations (IC50) of vincristine on HT-29par and HT-29mdr1 cells were 2.5 and 15 ng/mL, respectively. The MRK-16 monoclonal antibody did not affect the vincristine sensitivity of the HT-29par cells. Pretreatment of HT-29mdr1 cells with 10 micrograms/mL MRK-16 in tissue culture partially restored the vincristine sensitivity (IC50 = 7 ng/mL). This modulation of vincristine sensitivity by MRK-16 was then tested in vivo. The median survival times of mice given intraperitoneal transplants of 5 x 10(6) HT-29par or HT-29mdr1 were 37 and 39 days, respectively. Treatment of mice with 1 mg/kg vincristine weekly for 3 weeks, beginning 10 days after tumor injection, resulted in a significant increase in the median survival time of the HT-29par tumor-bearing mice (68 days, P less than .0001), but it had no effect on the HT-29mdr1 tumor-bearing mice. However, treatment of mice bearing the HT-29mdr1 tumor with MRK-16 before vincristine therapy reversed the resistance to the drug (median survival time = 64 days, P less than .0001). The MRK-16 monoclonal antibody alone had no effect on the median survival time of mice given an injection of either HT-29par or HT-29mdr1 cells. These results suggest that strategies employing monoclonal antibody against gp170 may be clinically useful to reverse multidrug resistance.
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PMID:Reversal of drug resistance in a human colon cancer xenograft expressing MDR1 complementary DNA by in vivo administration of MRK-16 monoclonal antibody. 168 Nov 10

The relationship was analyzed between drug resistance and MDR1 (with MDR signifying multiple drug resistance) and glutathione S transferase-pi (GST-pi) gene expression in four stomach and four colon cancer cell lines. Northern blot analysis by pmdr1 probe showed that stomach cancer cell lines had no detectable level of MDR1 mRNA expression. By contrast, some levels of MDR1 mRNA expression were found in two colon cancer cell lines, indicating doxorubicin resistance. To examine the MDR1 mRNA in each cell level, in situ hybridization was used. It was found that all colon cell lines and two stomach cell lines had more silver grains per cell than KB cells (a human KB kidney epidermoid carcinoma cell line). However, the number of silver grains in each cell was heterogeneous in the colon and stomach cell lines. Low-level MDR1 mRNA expression could be detected even in cell lines without MDR1 mRNA expression by northern blot hybridization. These results suggest the possibility that all gastrointestinal cell lines can acquire multiple drug resistance. In addition, all examined gastrointestinal cell lines had high GST-pi mRNA expression. This GST-pi gene expression shows cisplatin resistance in the examined cell lines. Heterogeneity of GST-pi mRNA expression also was shown at the cellular level.
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PMID:Expression of MDR1 and glutathione S transferase-pi genes and chemosensitivities in human gastrointestinal cancer. 173 85

The expression of MDR1 gene was investigated in human solid tumors with respect to adriamycin resistance. Forty fresh human surgical specimens were analyzed by RNA dot blot assay for their expression of the human MDR1 gene and by immunohistological staining using a monoclonal antibody against P-glycoprotein (MDR1 gene product). The MDR1 mRNA level was increased in 11 cases of 40 cancer patients, including three rectal cancers, two breast cancers, two gastric cancers, one colon cancer, one renal cell carcinoma, one gall bladder cancer and one malignant lymphoma of stomach. However, considerable variation of the MDR1 mRNA level was noted among cancers of a specific type. Immunohistochemical studies with the monoclonal antibody were shown to be positive in 18 tumors. In all tumors tested, the MDR1 mRNA level and the immunohistochemical analysis showed a significant correlation. However, two of five tumors which resisted adriamycin treatment were found to be negative in MDR1 transcript, but positive in immunohistological analysis. These results indicate that immunohistochemical analysis would be more sensitive for detecting P-glycoprotein-expression, and that resistance to adriamycin, being multifactorial, can be associated at least, in part with the increased amount of MDR1 gene product.
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PMID:Expression of the multidrug resistance gene in human tumors. 198 Sep 15

Cell lines established from the human colorectal and gastric cancers may provide very useful tools to the study of the disease and to develop and test new therapeutic approaches, and a large bank of well-characterized cell lines should reflect the diversity of tumor phenotypes and provide adequate models for the study of tumor heterogeneity. Colorectal lines are relatively easy to establish, while gastric cancer cell lines remain extremely difficult to propagate in long-term culture, and the number of cell lines is very limited. In this paper, we describe the up-to-date results of the characteristics of our nine colorectal cancer cell lines and four gastric cancer cell lines. Based on culture, xenograft, and ultrastructural morphologies, these cell lines could be subtyped into well-differentiated, moderately differentiated, poorly differentiated, and mucinous carcinomas. Basic properties concerning expression and secretion of antigens, neuroendocrine features, receptor binding of various gastrointestinal hormones and neurotransmitters, cytogenetic studies, gene amplification and expression, and chemosensitivity profiles are described. In particular, a greater number of receptors for hormones and neurotransmitters are expressed on human colorectal cancer cell lines compared to gastric cancer cell lines, raising the possibility that gastrointestinal hormones may have a greater autocrine effect on colon cancer cell growth. Despite major differences in the biology of colorectal cancer and gastric cancer as indicated by clinical studies, the multiple properties that we examined reveals marked similarities between the colorectal and gastric cancer cell lines. However, in vitro chemosensitivity patterns to cytotoxic drugs are very different in colorectal and gastric cell lines. Some of these observations may be due to the relatively low expression of the multidrug-resistance-associated (MDR1) gene in gastric cancer cell lines. In addition, colorectal cancer cell lines express receptors for peptide hormones more frequently.
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PMID:Biology of colorectal and gastric cancer cell lines. 880 95

Drug resistance, both primary and acquired, is a major obstacle to advances in cancer chemotherapy. In vitro, multidrug resistance can be mediated by P-glycoprotein (PGY1), a cell surface phosphoglycoprotein that acts to efflux natural products from cells. PGY1 is encoded by the MDR1 gene located at 7q21.1. Overexpression of MDR1 has been demonstrated in many cancers, both in patient tumors and in cell lines selected with a variety of chemotherapeutic agents. Recent studies in drug-selected cell lines and patients samples have identified hybrid mRNAs comprised of an active, but apparently random, gene fused 5' to MDR1. This observation indicates that random chromosomal rearrangements, such as translocations and inversions, leading to "capture" of MDR1 by constitutively expressed genes may be a mechanism for activation of this gene following drug exposure. In this study, fluorescence in situ hybridization (FISH) using whole chromosome paints (WCP) and bacterial artificial chromosome (BAC)-derived probes showed structural rearrangements involving 7q in metaphase and interphase cells, and comparative genomic hybridization (CGH) revealed high levels of amplification at chromosomal breakpoints. In an adriamycin-selected resistant colon cancer line (S48-3s/Adr), WCP4/WCP7 revealed t(4;7)(q31;q21) and BAC-derived probes demonstrated that the breakpoint lay between MDR1 and sequences 500-1000 KB telomeric to it. Similarly, in a subline isolated following exposure to actinomycin D (S48-3s/ActD), a hybrid MDR1 gene composed of heme oxygenase-2 sequences (at 16p13) fused to MDR1 was identified and a rearrangement confirmed with WCP7 and a subtelomeric 16p probe. Likewise, in a paclitaxel-selected MCF-7 subline where CASP sequences (at 7q22) were shown to be fused to MDR1, WCP7 showed an elongated chromosome 7 with a homogeneously staining regions (hsr); BAC-derived probes demonstrated that the hsr was composed of highly amplified MDR1 and CASP sequences. In all three selected cell lines, CGH demonstrated amplification at breakpoints involving MDR1 (at 7q21) and genes fused to MDR1 at 4q31, 7q22, and 16p13.3. Finally, in samples obtained from two patients with drug refractory ALL, BAC-derived probes applied to archived marrow cells demonstrated that a breakpoint occurred between MDR1 and sequences 500-1000 KB telomeric to MDR1, consistent with a random chromosomal rearrangement. These results support the proposal that random chromosomal rearrangement leading to capture and activation of MDR1 is a mechanism of acquired drug resistance.
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PMID:Cytogenetic and molecular characterization of random chromosomal rearrangements activating the drug resistance gene, MDR1/P-glycoprotein, in drug-selected cell lines and patients with drug refractory ALL. 971 96

Efficacy of chemotherapy is limited in numerous tumors by specific cellular mechanisms that inactivate cytotoxic antitumoral drugs, such as ATP-dependent drug efflux and/or drug detoxification by glutathione. In reducing ATP pools and/or glutathione synthesis, it might be possible to enhance the efficacy of drugs affected by such resistance mechanisms. Reduction of the ATP pool and glutathione content is achievable in cancer cells by depleting the exogenous methionine (Met) supply and ethionine. Thus, the rationale for the present study was to use Met depletion to decrease the ATP and glutathione pools so as to sensitize tumors refractory to cytotoxic anticancer drugs. Met depletion was achieved by feeding mice a methionine-free diet supplemented with homocysteine. The effects of Met depletion combined with ethionine and/or chemotherapeutic agents were studied using human solid cancers xenografted into nude mice. TC71-MA (a colon cancer) SCLC6 (a small cell lung cancer), and SNB19 (a glioma) were found to be refractory to cisplatin, doxorubicin, and carmustine, respectively. These three drugs are used to treat such tumors and are dependent for their activity on the lack of cellular ATP- or glutathione-dependent mechanisms of resistance. TC71-MA, SCLC6, and SNB19 were Met dependent because their proliferation in vitro and growth in vivo were reduced by Met depletion. Cisplatin was inactive in the treatment of TC71-MA colon cancer, whereas a methionine-free diet, alone or in combination with ethionine, prolonged the survival of mice by 2-fold and 2.8-fold, respectively. When all three approaches were combined, survival was prolonged by 3.3-fold. Doxorubicin did not affect the growth of SCLC6, a MDR1-MRP-expressing tumor. A Met-deprived diet and ethionine slightly decreased SCLC6 growth and, in combination with doxorubicin, an inhibition of 51% was obtained, with survival prolonged by 1.7-fold. Combined treatment produced greater tumor growth inhibition (74%) in SCLC6-Dox, a SCLC6 tumor pretreated with doxorubicin. Growth of SNB19 glioma was not inhibited by carmustine, but when it was combined with Met depletion, survival duration was prolonged by 2-fold, with a growth inhibition of 80%. These results indicate the potential of Met depletion to enhance the antitumoral effects of chemotherapeutic agents on drug-refractory tumors.
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PMID:Methionine depletion enhances the antitumoral efficacy of cytotoxic agents in drug-resistant human tumor xenografts. 1069 May 50

Studies on the role of genetically polymorphic enzymes like cytochrome P450 1A1, arylamine N-acetyltransferase 2 or glutathione S-transferase M1 as cancer susceptibility factors date back more than 20 years, and some associations have been confirmed in several studies and meta-analyses. Overall, the extent of risk modulation due to these polymorphisms is only moderate but remains epidemiologically relevant. The role of some of these polymorphisms in human health may even be ambiguous: rapid acetylation, for example, protects from urinary bladder cancer but appears to increase the risk of laryngeal, lung and colon cancer. The first genetic polymorphisms in xenobiotics transporters such as P-gp (MDR1) and MRP2 have recently been identified. These polymorphisms may have great impact as cancer susceptibility factors as well as factors modulating the outcome of cancer treatment. Enzymes involved in generation or detoxification of reactive oxygen species also have to be considered; one of these enzymes, myeloperoxidase, constitutes a relatively strong lung cancer risk factor, as confirmed in 4 independent studies. Other genes, including those coding for DNA repair enzymes, signal transduction and cell growth regulation, may ultimately prove more important than the metabolic enzymes as cancer susceptibility factors. Study designs in molecular genetic epidemiology are evolving; large ongoing prospective trials increasingly allow confirmatory nested case control studies to be performed. However, carefully controlled, large case-control studies will remain the mainstay in molecular genetic epidemiology. Molecular genetic epidemiological evaluation of response to chemoprevention as well as response to the adverse events of cancer chemotherapy are likely to provide results that may be useful for individualized prevention and treatment in the near future. Since routine genotyping of all persons is now feasible, something like a genotype passport may soon become reality, and molecular and clinical epidemiological studies will have to provide the basis for understanding how to use genotype data for the benefit of the population.
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PMID:Molecular genetics of cancer susceptibility. 1097 Dec 8

Genotoxic stress leads to nuclear translocation of the Y-box transcription factor YB-1 and enhanced expression of the multidrug resistance gene MDR1. Because hyperthermia is used for the treatment of colon cancer in combination with chemoradiotherapy, we investigated the influence of hyperthermia on YB-1 activity and the expression of multidrug resistance-related genes. Here we report that hyperthermia causes YB-1 translocation from the cytoplasm into the nucleus of human colon carcinoma cells HCT15 and HCT116. Nuclear translocation of YB-1 was associated with increased MDR1 and MRP1 gene activity, which is reflected in strong efflux pump activity. However, a combination of hyperthermia and drug treatment effectively reduced cell survival of the HCT15 and HCT116 cells. These results demonstrate that activation of MDR1 and MRP1 gene expression and increased efflux pump activity after hyperthermia were insufficient to cause an increase in drug resistance in colon cancer cell lines. The ability of hyperthermia to abrogate drug resistance in the presence of an increase in functional MDR proteins may provide an explanation for the efficacious results seen in the clinic in colon cancer patients treated with a combination of hyperthermia and chemotherapy.
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PMID:Hyperthermia-induced nuclear translocation of transcription factor YB-1 leads to enhanced expression of multidrug resistance-related ABC transporters. 1136 62

gamma-Glutamylcysteine synthetase (gamma-GCS) is a key enzyme in glutathione (GSH) synthesis, and is thought to play a significant role in intracellular detoxification, especially of anticancer drugs. Increased levels of GSH are commonly found in the drug-resistant human cancer cells. We designed a hammerhead ribozyme against gamma-GCS mRNA (anti-gamma-GCS Rz), which specifically down-regulated gamma-GCS gene expression in the HCT-8 human colon cancer cell line. The aim of this study was to reverse the cisplatin and multidrug resistance for anticancer drugs. The cisplatin-resistant HCT-8 cells (HCT-8DDP cells) overexpressed MRP and MDR1 genes, and showed resistance to not only cisplatin (CDDP), but also doxorubicin (DOX) and etoposide (VP-16). We transfected a vector expressing anti-gamma-GCS Rz into the HCT-8DDP cells (HCT-8DDP/Rz). The anti-gamma-GCS Rz significantly suppressed MRP and MDR, and altered anticancer drug resistance. The HCT-8DDP/Rz cells were more sensitive to CDDP, DOX and VP-16 by 1.8-, 4.9-, and 1.5-fold, respectively, compared to HCT-8DDP cells. The anti-gamma-GCS Rz significantly down-regulated gamma-GCS gene expression as well as MRP/MDR1 expression, and reversed resistance to CDDP, DOX and VP-16. These results suggested that gamma-GCS plays an important role in both cisplatin and multidrug resistance in human cancer cells.
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PMID:Reversal of cisplatin and multidrug resistance by ribozyme-mediated glutathione suppression. 1150 53

The effects of various flavonoids and carotenoids on Rhodamine 123 accumulation in multidrug-resistant Colo 320 human colon cancer cells expressing MDR1/LRP were studied. The Colo 205 cell line was used as a drug-sensitive control. Rotenon, Catechin, Neohesperidin, Naringin, Robinin, Phloridzin, Robinetin, Dihydrobinetin, Dihydrofisetin, Kampferol, Dihidroquercetin, Sakuranin and Sakuranetin were tested on Colo 320 cells: only Rotenon was found to be effective as regards multidrug resistance (MDR) reversal, while a majority of the flavonoids, such as Catechin, Neohesperidin, Naringin, Robinin, Phloridzin, Dihydrobinetin and Sakuranetin, had only marginal effects on Rhodamine 123 accumulation. The tested carotenoids (beta-Cryptoxanthin, Luteoxanthin, Anteroxanthin, Violeoxanthin, Apple peel fetoxanthin, Lutein, Violaxanthin and Neoxanthin) were able to increase Rhodamine 123 accumulation in Colo 320 cells. Verapamil was applied as a resistance-modifying positive control. The levels of apoptosis induction in drug-resistant and sensitive cell lines were also compared. The results indicated that the tested flavonoids were weak apoptosis inducers on MDR and parent cells, without significant differences. A majority of the carotenoids induced only early apoptosis, but apoptosis and cell death were not induced in MDR colon cancer cells.
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PMID:Effects of selected flavonoids and carotenoids on drug accumulation and apoptosis induction in multidrug-resistant colon cancer cells expressing MDR1/LRP. 1579 8


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