Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027627 (metastases)
 103,950 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In some human malignancies resistance to chemotherapy is caused by an energy-dependent efflux system, responsible for the removal of chemotherapeutics out of the resistant tumor cells. A major component of this efflux system is the permeability glycoprotein (p-glycoprotein), which depends on the multidrug-resistance gene MDR1. We have tested p-glycoprotein in primary and metastatic human melanoma by use of the monoclonal antibody C219; a substantial expression was only observed in 1/37 primary melanomas and in 1/27 melanoma metastases. None of the patients with negative metastases responded to chemotherapy. Moreover a complete remission of metastatic growth was observed in the patient with the metastasis significantly expressing the p-glycoprotein. Sequential studies revealed no significant increase of p-glycoprotein-positive cells during and after chemotherapy. We conclude that drug resistance in human melanoma does not usually depend on the p-glycoprotein-related efflux system. Other mechanisms are obviously responsible for drug resistance in this human malignancy.
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PMID:p-glycoprotein expression in malignant melanoma. 167 31

In order to improve survival in a disease where the majority of deaths occur from metastases, the integration of systemic chemotherapy is crucial. Research efforts must continue to focus on refining case selection criteria, improving complete response proportions, and overcoming drug resistance. The blanket recommendation of a single therapeutic strategy such as radical surgery, chemotherapy, or radiation therapy to all patients is quickly becoming an outdated approach. Refinements in the understanding of the clinical, pathologic, and molecular features of urothelial tumors will ultimately improve case selection. Evaluation of NM23 RNA levels, or DNA ploidy and T138 surface antigen expression, which have been shown to correlate with metastatic potential, may hold important therapeutic implications. The use of hematopoietic growth factors has the potential to improve both the tolerance of chemotherapy and complete response proportions, a prerequisite for cure. A recent report from Japan of granulocyte colony-stimulating factor with MVAC and other chemotherapy regimens for urothelial tumors corroborated an initial report in reducing the duration of neutropenia. However, the dose response curves for most of the known active agents are not well defined and, ultimately, new agents and strategies will be required. Gallium nitrate, when administered by continuous intravenous infusion, has significant single agent activity in cisplatin-refractory patients with 9/31 responses (29%), including 6 CRs (19%) and further studies are warranted. Drug resistance remains a major obstacle, and as the mechanisms are unravelled, more rational therapies can be designed. For example, resistance to Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH) and vinblastine, two components in the MVAC regimen, are mediated in part by the MDR1 gene. Attempts are ongoing to identify prospectively those tumors with high levels of expression that may be more amenable to treatment with drugs that are not affected by this mechanism. The neoadjuvant approach allows an in vivo assessment of response to chemotherapy as well as the potential for bladder preservation. In most cases additional therapy directed at the primary is required as clinical understaging is a significant problem and pCR proportions are less than 30%. For some patients, initial surgery followed by treatment based on pathologic criteria may represent a better strategy. In these cases the recommendation for adjuvant treatment potentially limits therapy to a population of patients for whom therapy is essential. Based on available data, this would include patients with positive lymph nodes at the time of surgery. Ideally, patients with invasive bladder cancer should be entered into clinical trials designed to assess the impact of these strategies on survival.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The evolving role of chemotherapy for muscle infiltrating bladder cancer. 177 75

Drug resistance is one of the major impediments to the treatment of advanced neuroblastoma. Two neuroblastoma cell lines established from the same patient before (KP-N-AY) and after (KP-N-AYR) chemotherapy are described. Both cell lines were established from bone-marrow metastases of a 2 1/2-year-old patient with stage IV neuroblastoma. Chromosomal analysis, catecholamine assessment and the surface membrane phenotype of these cell lines confirmed that the tumors were of neuroblastoma origin. Compared with the KP-N-AY cell line, the KP-N-AYR line had decreased N-myc amplification but increased N-myc expression. An in vitro sensitivity test using a clonogenic assay showed the KP-N-AYR cell line to be 3.0-fold resistant to adriamycin and 2.7-fold resistant to cis-platinum as compared with the KP-N-AY cell line. The expression of the multi-drug-resistance gene (MDR1) was not observed in either cell line by the ribonuclease protection assay. The KP-N-AY cell line revealed only faint MDR1 RNA by the polymerase chain reaction, whereas the KP-N-AYR cell line had no expression of the MDR1 gene. The level of glutathione-S-transferase-pi was significantly higher in the KP-N-AYR cell line than in the KP-N-AY cell line. These findings suggest that the development of clinical drug resistance may be associated with the enhanced glutathione-S-transferase-pi activity but not with MDR1 gene expression.
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PMID:Different drug sensitivity in two neuroblastoma cell lines established from the same patient before and after chemotherapy. 200 54

We investigated four mechanisms of intrinsic chemoresistance in a series of 67 human brain tumours including 31 gliomas (one grade I ganglioglioma, nine grade II and 10 grade III astrocytomas, 11 glioblastomas), 13 cerebral metastases, one medulloblastoma, one malignant teratoma, three ependymomas and 18 meningiomas. We studied four genes by northern blotting: multidrug-resistance (MDR 1), glutathione-s transferase (GST pi), dihydrofolate reductase (DHFR), and topoisomerase II (Topo II). The Topo II gene was absent in the normal adult brain (100%) and in 64% of the tumour samples tested. A second gene, GST pi, was found to be overexpressed in 38% of brain tumours. The two other chemoresistance-related genes were occasionally overexpressed in brain tumours (2% for MDR1, 9% for DHFR). Our results provide evidence that chemoresistance is intrinsic to the brain tissue and seems likely to be a multifactorial process.
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PMID:A study of the expression of four chemoresistance-related genes in human primary and metastatic brain tumours. 838 72

Anthracyclines were introduced for the treatment of breast cancer in the 1970s and were considered the most active single agents until the recent introduction of the taxoids. Although incorporation of anthracyclines into combination regimens has been shown to improve clinical outcomes, the duration of response and survival in women with metastatic disease is still modest, and 50% of women treated with adjuvant chemotherapy eventually relapse. Intrinsic and acquired drug resistance, leading to untreatable disease, are fundamental reasons for clinical failure in breast cancer, but the clinical relevance of the various known mechanisms of drug resistance is not clear. P-glycoprotein (Pgp)-mediated multidrug resistance, the most studied form of anthracycline resistance, can be inhibited by a variety of chemicals. While in vitro studies have demonstrated the efficacy of some Pgp inhibitors, and led to the development of more clinically acceptable agents, clinical studies have not shown a consistent advantage in using Pgp inhibitors. Since Pgp is a physiologic efflux mechanism, consideration also should be given to the possible consequences of its inhibition. Studies with Pgp knock-out transgenic mice suggest that Pgp is not essential for life, but that Pgp inhibition may make some tissues, such as the brain, more vulnerable to cytotoxic drugs. Correlating overexpression of the MDR1 gene in human tumor samples with treatment failure has not proved straightforward, and further studies are needed to clarify the contribution of multidrug resistance mechanisms to clinical anthracycline resistance. Mechanisms other than drug efflux pumps, which may contribute to anthracycline resistance, include changes in topoisomerase II, the major cellular target of anthracyclines. There remains a gulf between the laboratory definitions of drug resistance, which can be elucidated in great detail, and the clinical definition, which is based on the time to treatment failure. New drugs still need to be assessed empirically in the clinic, and these results may then be correlated with laboratory findings. We cannot yet reliably predict clinical efficacy, cross-resistance, or the mechanisms responsible for treatment failure from laboratory studies.
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PMID:Anthracycline resistance: the problem and its current definition. 927 1

To evaluate the clinically important mechanisms of drug resistance in breast cancer, the expression of the MRP gene and the corresponding one for the MDR1 gene were determined in primary breast carcinoma specimens by both reverse transcription-PCR (n = 134) and immunohistochemistry (n = 63). Expression of MRP RNA was observed in all breast cancer specimens. MDR1 RNA was detected in 80 (60%) of the carcinomas. Staining with monoclonal antibodies QCRL-1 and QCRL-3, which both recognize MRP, was strong in 15 (24%) and weak in the remaining 48 specimens (76%). Staining with C219, which recognizes P-glycoprotein, was strong in 6 (9%), weak in 30 (48%), and negative in 27 (43%) of the samples. Strong MRP staining was more frequent in T3 and T4 tumors than in T1 and T2 tumors and in the primary tumors of patients with distant metastases but was independent of age, menopausal status, histology, histological grade, estrogen receptor, progesterone receptor, and lymph node involvement. No correlation between MRP staining and expression of MDR1 RNA or P-glycoprotein was observed. Thus, these results indicate expression of both the MRP gene and the MDR1 gene in primary breast carcinomas and suggest that clinical drug resistance in breast cancer is most likely multifactorial.
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PMID:MRP and MDR1 gene expression in primary breast carcinomas. 981 92

P-glycoprotein (Pgp) encoded by the MDR1 gene, a predictor of chemoresistance, may also serve as a prognosticator of clinical outcome in cancer patients. The mutant tumour-suppressor p53 protein has been shown to activate the MDR1 promoter, whereas the wild-type p53 represses this activity in cultured cells. We have described the differential expression of Pgp and p53 proteins in betel- and tobacco-related oral tumorigenesis in the Indian population. Herein, Pgp expression was analysed in relation to p53 protein accumulation in pre-malignant and malignant oral lesions by immunohistochemical and flow-cytometric analyses. The relationship between Pgp and p53 protein accumulation and clinicopathological parameters as well as prognosis was determined. Expression of Pgp was observed in 81% of oral squamous cell carcinomas (SCCs) and 71% of pre-malignant lesions. Sixty-five of 75 p53-positive oral SCCs and 21/24 p53-positive pre-malignant lesions showed expression of Pgp. Significant correlation between Pgp and p53 expression was found not only in oral SCCs but also in pre-malignant lesions. Co-expression of Pgp and p53 proteins was indicative of poor prognosis. Follow-up studies of 35 patients showed that 7 of 10 oral SCCs with accumulation of Pgp and p53 proteins also exhibited shorter disease-free survival (recurrence/metastases). Our findings provide clinical evidence for a significant association between Pgp and p53 protein expression in oral tumorigenesis and may account for the aggressive nature of the tumour and poor prognosis.
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PMID:P-glycoprotein is positively correlated with p53 in human oral pre-malignant and malignant lesions and is associated with poor prognosis. 998 37

The prognosis of patients with tumors expressing P-glycoprotein (P-gp), the MDR1 gene product, is generally poor. It is assumed that this is due to decreased tumor responsiveness that results from decreased drug accumulation. We observed that treatment of animals bearing MDR1-transfected leukemic cells with P-gp substrates (i.e., drugs that are transported by P-gp) significantly worsened host survival compared to treatment with vehicle or non-P-gp substrates. This effect was seen with cancer chemotherapeutic agents (paclitaxel and vincristine) and with the MDR modulator, trans-flupenthixol. To determine the mechanism(s) underlying this observation, we studied alterations in pharmacokinetics, pharmacodynamics, and metastasis. We found that the drug-induced acceleration of disease was associated with increased metastases. P-gp(+) cells treated with P-gp substrates demonstrated several pro-metastatic features, including membrane ruffling and invasion through a hepatocyte monolayer. These results suggest that the treatment of MDR tumors with P-gp substrates may produce changes in malignant behavior that could adversely affect therapeutic outcomes.
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PMID:Treatment of multidrug resistant (MDR1) murine leukemia with P-glycoprotein substrates accelerates the course of the disease. 1058 Nov 84

Overexpression of P-glycoprotein (Pgp), a multidrug transporter encoded by the MDR1 gene, is associated with chemoresistance in some human solid tumor malignancies. To date, analyses of MDR1 levels in solid tumors have examined constitutive increases in expression at relapse. In the present study, we have evaluated the acute induction of MDR1 gene expression in a solid human tumor as a function of time in response to in vivo exposure to chemotherapy. Five patients with unresectable sarcoma pulmonary metastases underwent isolated single lung perfusion with doxorubicin. Relative MDR1 gene expression was measured in metastatic tumor nodules and normal lung specimens after initiation of chemoperfusion. In four of five patients, a 3-15-fold (median, 6.8) increase in MDR1 RNA levels was detected in tumors at 50 min after administration of doxorubicin. In contrast, normal lung samples had very low levels of MDR1 RNA prior to perfusion, and no acute increases were observed after therapy. These findings demonstrate, for the first time, that MDR1 gene expression can be rapidly activated in human tumors after transient in vivo exposure to cytotoxic chemotherapy.
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PMID:Rapid activation of MDR1 gene expression in human metastatic sarcoma after in vivo exposure to doxorubicin. 1058 42

The study evaluated the contribution of serum PS100 assay to the detection of lymph node metastases during the follow-up of patients previously treated for a malignant melanoma, in addition to (99m)Tc sestamibi (MIBI) scintigraphy and investigation for gene MDR1, in order to detect chemoresistance phenomena. The study included 37 patients with a clinically questionable lymph node around basin lymphatic areas of the previously surgically-treated malignant melanoma. The sensitivity and specificity of PS100 assay were 91% and 86.5%, respectively. The sensitivity and specificity of MIBI scintigraphy were 95% and 85%, respectively. Overexpression of gene MDR1 was observed in six cases. In the event of negative scintigraphic findings, the concomitant analysis of PS100 levels and the scintigraphic result enabled the metastatic MDR+ patients to be distinguished from the non-metastatic patients. PS100 assay may therefore be proposed for the follow-up of malignant melanoma.
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PMID:Interest of PS100 assay when (99m)Tc sestamibi scintigraphy failed to identify lymph node metastases of melanoma. 1152 50


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