Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C1140680 (ovarian cancer)
 28,141 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumour levels of O6-alkylguanine-DNA-alkyltransferase (O6 AT) and glutathione content (GSH) were correlated with 1, 3-Bis (2-chloroethyl)-1-nitrosourea (BCNU) sensitivity in two human ovarian cancer xenografts (HOC8 and HOC18) and in two human glioblastoma xenografts (HG12 and HG15). HOC8 and HOC18, which were not responsive to BCNU treatment, showed O6 AT levels 14 and 23-fold higher than HG12 that was moderately sensitive to the same BCNU treatment. HG15, which was more sensitive to BCNU than HG12, showed significantly lower O6 AT levels. GSH levels were similar in all tumor xenografts. These data further stress the importance of O6 AT level as a relevant parameter for nitrosourea response in human tumours.
 ...
PMID:Tumour levels of O6-alkylguanine-DNA-alkyltransferase and sensitivity to BCNU of human xenografts. 129 58

We established a cisplatin-resistant human ovarian cancer cell line (HAC2/0.1) from the parent cell line (HAC2/P) by continuous exposure of HAC2/P to 0.1 microgram of cisplatin/ml. Drug sensitivity determined by colony assay revealed that HAC2/0.1 was 2.4 times as resistant to cisplatin as the parental cell line. HAC2/0.1 was 12.1 and 2.0 times as resistant to (4s)-4,11-diethyl-4-hydroxy-9-[(4-piperidinopiperidino)-carbony loxy]dione hydrochloride trithydrate (CPT-11) and 7-ethyl-10-hydroxy-CPT (SN-38; an active metabolite of CPT-11), respectively, than HAC2/P. We studied the mechanism of cross-resistance to CPT-11 in HAC2/0.1. The glutathione (GSH) content was higher in HAC2/0.1 than in HAC2/P. The activity of DNA topoisomerase I and the accumulation of CPT-11 and SN-38 were also the same. On the other hand, the conversion of CPT-11 to SN-38 in HAC2/0.1 was about 3-fold less than in HAC2/P. Treatment of the parent and resistant cell lines with buthionine sulfoxamine (BSO) decreased the GSH content of both cell lines and decreased the 50% inhibitory concentrations of all the tested drugs for HAC2/0.1. The accumulation of CPT-11 in HAC2/0.1 but not in HAC2/P was increased by BSO treatment. On the other hand, in HAC2/P the 50% inhibitory concentrations of SN-38 and CPT-11 were not influenced by BSO treatment. The 50% inhibitory concentration of CPT-11 for HAC2/0.1 was not reduced by BSO treatment to the level for HAC2/P, even though the GSH content had been reduced more than in HAC2/P. These results show that there is no clear relationship between GSH and resistance to CPT-11. The decreased conversion of CPT-11 to SN-38 is considered to be the main cause of resistance to CPT-11 in this cell line.
 ...
PMID:Mechanism of cross-resistance to a camptothecin analogue (CPT-11) in a human ovarian cancer cell line selected by cisplatin. 134 10

Platinum-based chemotherapy has led to an improvement in complete response rates and duration of median remission, but has only given a modest improvement in overall survival in patients with advanced ovarian cancer. Chemotherapy will in the future focus upon: (1) improving the complete remission rate with new induction regimens; (2) identifying strategies capable of converting partial remission into complete remission; (3) preventing or delaying recurrences in patients who do achieve a complete remission; (4) identifying mechanisms of antineoplastic drug resistance and pharmacologic techniques capable of reversing drug resistance. Among the treatment approaches being utilized are high-dose chemotherapy with autologous bone marrow transplantation, development of new chemotherapeutic regimens which include Taxol and hexamethylmelamine, and intraperitoneal chemotherapy. In addition, our understanding of the mechanisms of antineoplastic drug resistance has led to the development of novel therapeutic approaches. It has been demonstrated that resistance to platinum and alkylating agents is associated with both increased concentrations of cellular glutathione (GSH) as well as an increased capacity of tumor cells to repair damage to DNA. Inhibition of GSH biosynthesis with buthionine sulfoximine (BSO), a synthetic inhibitor of the enzyme gamma glutamyl cysteine synthetase, has led to the potentiation of alkylating agent activity in vitro and in vivo. A phase I trial of BSO plus melphalan is currently in progress and a trial of BSO plus carboplatin is planned. Inhibition of the DNA repair process with aphidicolin potentiates the cytotoxicity of cisplatin in drug-resistant tumor cells. Clinical trials of aphidicolin plus cisplatin await the completion of ongoing phase I trials of aphidicolin.
 ...
PMID:Role of chemotherapy in the future treatment of ovarian cancer. 135 5

The diastereoisomeric dichloro-[1-(2-, 3- and 4-hydroxyphenyl)-2-phenylethylenediamine]platinum(II) complexes were tested on two human ovarian cancer cell lines NIH: OVCAR-3 and SK-OV-3, both resistant against cisplatin. Dichloro-[threo-1-(3-hydroxyphenyl)-2-phenylethylenediamine]platinum(II) (threo-5-PtCl2) proved to be the most active representative of the new series, producing cytocidal effects at a concentration range of 2.5 to 5.0 microM on the NIH: OVCAR-3 cell line. On the more resistant SK-OV-3 cell line, threo-5-PtCl2 was only moderately active, while in combination with BSO, a GSH level lowering compound, threo-5-PtCl2 showed a strong synergistic effect.
 ...
PMID:Dichloro-[1-(hydroxyphenyl)-2-phenylethylenediamine]platinum(II) complexes: testing on the human ovarian cancer cell lines NIH: OVCAR3 and SK OV 3. 160 22

Glutathione (GSH) is a sulfur-containing nucleophile that protects against cisplatin-induced renal toxicity without reducing the antitumor activity of the cytotoxic agent. To document further the clinical role of GSH in improving the outcome of cisplatin-containing regimens, the feasibility of the GSH/cisplatin combination using a low-volume hydration protocol was evaluated in untreated ovarian cancer patients. Twelve patients at stage III (minimal residual disease) and 23 with localized disease at high risk for recurrence were treated with cisplatin (90 mg/m2, i.v. in 250 ml of normal saline over 30 min) and cyclophosphamide (600 mg/m2 i.v.) every 3 weeks. GSH (5 g in 200 ml of normal saline) was administered by a short-term infusion (15 min) prior to cisplatin. The hydration protocol consisted of 1 liter of fluids without diuretics. The treatment was well tolerated; no nephrotoxic or neurotoxic manifestations were observed. The renal excretion of cisplatin (23%) at 24 hours following infusion was lower than expected using a standard i.v. hydration protocol. No reduction of renal elimination of cisplatin could be detected in subsequent courses, thus suggesting a minimal degree of impairment in renal function. In the series of evaluable patients (11) with stage III disease, 9 had complete pathological response. In the series of patients with no clinically detectable disease initially, all were disease-free at treatment completion. Taken together with previous observations, these results support the view that the use of GSH is a successful approach in the attempt to optimize cisplatin treatment, providing a new modality of drug administration for out-patient treatment.
 ...
PMID:A feasibility study of cisplatin administration with low-volume hydration and glutathione protection in the treatment of ovarian carcinoma. 174 19

Recent efforts to improve the response rates in advanced ovarian cancer with the use of high-dose cisplatin have been limited by unacceptable toxicity. Based on experimental and clinical studies indicating that reduced glutathione (GSH) is a protective agent against cisplatin-induced toxicity, a new high-dose regimen including GSH as a chemoprotector was designed in an attempt to improve the efficacy and therapeutic index of cisplatin. A total of 40 consecutive patients with stage III (bulky) and IV ovarian carcinoma were treated with cisplatin (40 mg/m2 daily for 4 consecutive days) and cyclophosphamide (600 mg/m2 i.v. on day 4). The treatment was repeated every 3-4 weeks for five courses unless progression or severe toxicity occurred. Before each cisplatin administration, patients received GSH (1,500 mg/m2) i.v. over 15 min, with a standard i.v. hydration (2,000 ml fluid) without diuretics. Debulking surgery was initially attempted in 18 patients and, after 2-3 courses, in 16 patients; it could not be carried out in 6 patients. Three patients were not evaluable for response because they prematurely discontinued their treatment. In all, 23 patients (62%) achieved complete clinical remission (negative second-look laparotomy in 16), with an overall (complete + partial) response rate of 86%; 2 patients achieved disease-free status following second surgery. Nausea/vomiting was the most severe acute toxic effect; myelosuppression was acceptable. Renal impairment was effectively prevented by GSH. Neurotoxicity that was not associated with motor dysfunction was the most significant cumulative toxicity in patients (24/32) receiving 4-5 courses. The results of this study indicate that the use of GSH is a safe new method for high-dose cisplatin administration. This regimen is well-tolerated and very effective in ovarian cancer patients with bulky disease and warrants further evaluation.
 ...
PMID:Efficacy and safety of high-dose cisplatin and cyclophosphamide with glutathione protection in the treatment of bulky advanced epithelial ovarian cancer. 230 97

Intracellular glutathione (GSH) has been shown to be one of the major factors modulating tumor response to a variety of commonly used anti-neoplastic agents. In this study the GSH contents of human ovarian tumors from primary biopsies, nude mouse xenografts, and in vitro cell cultures were compared. Pronounced intratumor cell-to-cell heterogeneity in GSH content was observed in primary patient biopsies when assessed using flow cytometry. For example, in an ascites biopsy from a newly diagnosed patient, a 5.6-fold difference in GSH concentration existed between the cell subpopulations with the 5% highest and 5% lowest GSH contents. Similar intratumor heterogeneity in GSH content was also evident in nude mouse xenografts. In addition, for a particular tumor line, the intertumor variations of GSH content among individual whole tumors were much less than the intratumor variation among slices from an individual tumor. Nude mouse xenografts of human ovarian cancer had GSH contents that were on average only slightly lower (30%) than those found in primary biopsies. In contrast, tumor cells grown as in vitro cultures, particularly those in exponential growth phase, had GSH contents considerably greater (1.3- to 3.5-fold) than those found in situ. Plateau phase cultures, however, had lower GSH contents and were more comparable to those observed in tumors in vivo. Overall, it may be concluded that in situations where GSH plays an important part in determining tumor response to a particular treatment, nude mouse xenografts may represent the most appropriate experimental model system.
 ...
PMID:Heterogeneity of glutathione content in human ovarian cancer. 276 92

Patients with ovarian cancer often respond well to combination chemotherapy initially but the majority eventually relapse when, with further treatment, the initially successful regimen proves ineffectual. The cause of such failures frequently has been attributed to the development of drug resistance. Although the mechanisms of acquired resistance in situ are still poorly understood, studies in vitro have shown that cells selected for resistance to one drug often exhibit cross-resistance to other seemingly unrelated agents, suggesting a somewhat generalised mechanism of resistance. We have studied the role of glutathione (GSH) and drug transport in determining the sensitivity to adriamycin (ADR) of a panel of human ovarian cell lines established directly from biopsies of patients with diverse treatment histories. These cell lines exhibited inherent differences in sensitivity to ADR by a dose factor of up to 3; a difference that was considerably less than what has been reported when cells were selected for drug resistance in vitro. The differences in drug sensitivity reported here among the various cell lines appeared to be unrelated to drug transport, in terms of both influx and efflux. Moreover, although these cell lines have a wide range of GSH content, there was only a poor correlation between drug sensitivity and cellular GSH content per se. However, when exposed to a clinically relevant dose of ADR, the GSH content of cell lines that were 'sensitive' decreased, whereas that of cell lines that were 'resistant' increased. To take these time-dependent changes in GSH into consideration, the area under the GSH content versus time curve (AUC), with and without ADR treatment, was calculated for each cell line. When this latter factor was included in the analysis, greatly improved correlations were found between GSH kinetic parameters and responses to ADR. In particular, ADR resistance was found to be closely correlated with the positive changes in absolute GSH AUC following ADR treatment (r = 0.92; P less than 0.01). Using 35S-labelled cysteine and methionine as tracers, it was found that the essential difference between the 'resistant' and 'sensitive' lines was that the 'resistant' lines had higher steady-state rates of GSH synthesis than the 'sensitive' lines. These results demonstrate that changes in cellular GSH concentration during treatment may be an important indicator of tumour cell response to ADR.
 ...
PMID:Changes in cellular glutathione content during adriamycin treatment in human ovarian cancer--a possible indicator of chemosensitivity. 278 34

The biochemical responses to 8-week supplementary treatment with selenium and/or vitamin E were evaluated in 41 patients with gynaecological cancer during cytotoxic chemotherapy, in Finland, a selenium-deficient country. After the control course of 1-day treatment with cytostat agents, 11 patients received a combination of selenium and vitamin E (sodium selenate, 200 micrograms/day + vitamin E, 300 mg/day), 11 received selenium (sodium selenate, 200 micrograms/day) and seven received vitamin E (300 mg/day) as supplementary therapy, while 12 patients had no supplementary drugs. Sodium selenate alone and combined with vitamin E significantly increased the serum selenium levels, but the activity of serum glutathione peroxidase (GSH-Px) increased significantly only in the selenium- and vitamin E-treated patients with low initial GSH-Px activity. The cytotoxic chemotherapy did not change the activity of GSH-Px, while the concentrations of lipid peroxides decreased. Sodium selenate alone or with vitamin E did not modify this decrease. Sodium selenate alone significantly decreased the capacity of the platelets to produce thromboxane A2; it increased high-density lipoprotein cholesterol levels and prevented the cytotoxic-chemotherapy-associated increase of creatine kinase. Selenium supplementation might thus be beneficial during cytotoxic chemotherapy in ovarian cancer patients with low selenium levels.
 ...
PMID:Supplementation with selenium, vitamin E and their combination in gynaecological cancer during cytotoxic chemotherapy. 291 78

The mechanisms responsible for the cross-resistance between radiation and certain antineoplastic agents have been examined in human ovarian cancer cell lines. Cell lines established from patients at a time when they were resistant to combination chemotherapy regimens, which included cisplatin and an alkylating agent as well as cell lines with resistance induced in vitro to melphalan and cisplatin, all have increased cellular levels of glutathione (GSH) compared with drug-sensitive cell lines from untreated patients. In addition, cell lines with acquired resistance to melphalan and cisplatin, but not to doxorubicin, were cross-resistant to radiation. L-Buthionine sulfoximine (BSO), an irreversible inhibitor of gamma-glutamylcysteine synthetase, lowered GSH levels in all the resistant cell lines studied. Lowering of GSH levels to less than 10% of control values potentiated the in vitro cytotoxicity of melphalan and cisplatin. Furthermore, BSO was also shown to potentiate the cytotoxicity of melphalan in a nude mouse model system of ovarian cancer in which mice die of disseminated intra-abdominal carcinomatosis. The BSO administered in the drinking water decreased GSH levels by 96%. A single melphalan treatment of 5 mg/kg following GSH depletion produced a 72% increase in median survival time compared with treatment with melphalan alone. In addition, depletion of GSH levels in cell lines with acquired resistance to melphalan led to a marked sensitization of these cells to irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Mechanisms of cross-resistance between radiation and antineoplastic drugs. 335 59


1 2 3 4 5 6 7 8 Next >>