Interferon-beta does not change the level of O6-alkylguanine-DNA alkyltransferase in cancer patients' lymphocytes.
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Aged↗
Biomedical subjects
M D'Incalci
Publications and source records attributed to M D'Incalci.
Modulation of transcription factor--DNA interactions by anticancer drugs.
Anticancer drugs which bind DNA can alter the mechanism of gene transcription regulation. In this paper, we report examples of the ability of DNA-interacting drugs to alter the specific DNA binding and function of well-characterized transcription factors to their consensus DNA sequences. In particular, we have examined the effects of major groove binders such as methylating agents, chloroethylating agents and nitrogen mustards, and also minor groove binders such as distamycin derivatives. The results support the view that alterations of the DNA binding of transcription factors caused by the DNA-interacting agents may play an important role in the antitumor effects of these agents. Work is needed to obtain more highly DNA sequence-specific binders which can act as selective modulators of the transcription of genes involved in the malignant properties of cancer cells.
Alkylating Agents↗
Cyclosporin A markedly changes the distribution of doxorubicin in mice and rats.
Cyclosporin A (CsA) inhibits the membrane transport protein Pgp and can thus restore sensitivity to doxorubicin (Dx) and other antineoplastic agents in multidrug resistant cancer cells. Because Pgp is not expressed only in resistant tumor cells but also in normal tissues, CsA may modify the distribution of a concomitantly given antitumor agent which is a substrate for Pgp-mediated transport. We investigated Dx distribution in rats and mice injected i.p. with CsA then 30 min later with an i.v. dose of Dx. In both species CsA treatment markedly increased Dx concentrations in liver, adrenals and kidney, with a small but significant increase in the heart and no change in brain. The CsA-induced changes in Dx tissue levels were not related to inhibition of Dx metabolism or reduced fecal and renal Dx elimination. A marked delayed lethal toxicity of Dx was seen in mice treated with CsA and Dx but not with either drug alone. These results indicate that CsA can profoundly alter Dx pharmacokinetics and toxicity and suggest that caution is advisable when prescribing this combination to cancer patients using full Dx doses.
Animals↗
Intracellular glutathione heterogeneity in L1210 murine leukemia sublines made resistant to DNA-interacting anti-neoplastic agents.
Intracellular glutathione (GSH) content was measured by flow cytometry using monochlorobimane (mBCl) and by the enzymatic assay in a set of 6 sublines of murine L1210 leukemia cells made resistant to DNA-interacting agents having distinct mechanisms of action: L-phenylalanine mustard (L-PAM), 1,3-bis(2-chloroethyl)-I-nitrosourea (BCNU), cisplatin (DDP), N-deformyl-N-(4-N,N-bis(2-chloroethylamino) benzoyl) distamycin A (FCE 24517), doxorubicin (DX) and 3'-deamino-3' (2-methoxy-4-morpholinyl)-doxorubicin (FCE 23762). A significant correlation was demonstrated between the mean intracellular mBCl fluorescence values measured by flow cytometry and levels of GSH measured by the classical enzymatic assay, despite the possible influence of glutathione-S-transferases and of other thiols on the mBCl fluorescence. Although less specific, the flow cytometric method is more informative than the enzymatic assay, allowing detection of fluorescence distributions, which we proved to be characteristic of each subline. In order to assess a procedure enabling a quantitative analysis to be made of intercellular GSH heterogeneity, we propose the use of appropriate thresholds and parameters of the mBCl flow cytometric distribution. By use of this analysis procedure, distinct types of alterations, with respect to the heterogeneity distribution of the parental L1210 cell line, have been evidenced in resistant cells. A uniform increase in mBCl fluorescence was observed among cells of the sublines resistant to L-PAM and FCE-24517. The mean mBCl fluorescence increase in sublines resistant to DX and DDP was due to a higher number of cells with fairly high mBCl fluorescence, but still within the range spanned by the parental cell line. A less heterogeneous mBCl fluorescence distribution was found in the L1210 subline resistant to FCE 23762, which was, however, similar to a cloned sensitive line. Though GSH was linked to the principal cause of drug resistance only in the L-PAM-resistant cell line, alterations in heterogeneity, as detected by mBCl fluorescence distributions, were found in 5 out of 6 resistant lines.
Animals↗
In vitro cytotoxicity of GC sequence directed alkylating agents related to distamycin.
Imidazole containing analogues 7, 10, and 17 of distamycin wherein the C-terminus contain a dimethylamino moiety have been shown to selectively bind to the minor groove of GC-rich sequences. Accordingly, these agents were employed as vectors for the delivery of a variety of alkylating agents to GC-rich sequences. The alkylating agents are attached to the N-terminus of these vectors thus providing the benzoyl N-mustards (8, 15, and 18 that contain one, two, and three imidazole units, respectively) and substituted acetamides 11-14. Results from the ethidium displacement assay for the formamides 7, 10, and 17 and mustards 15 and 18 showed that these agents bind to calf thymus DNA, poly(dA.dT), poly(dG.dC), and also to coliphage T4 DNA, thus confirming their binding in the minor groove. The reduced binding constants of these compounds for poly(dA.dT) while still binding as strongly, or more strongly, to poly(dG.dC) than distamycin provided evidence for their acceptance of GC sequences. Selectivity for GC-rich sequences was also indicated by CD titration studies. Titration of 10, 15, 17, and 18 to poly(dA.dT) produced weak drug-induced CD bands at approximately 330 nm; however, interaction of these agents to poly(dG.dC) in equimolar drug concentrations gave strong bands in this region. Results from dialysis and cross-link gel experiments provided evidence of alkylation and cross-linking of DNA by the mustards which could explain their enhanced cytotoxicity over the formamido analogues. The bifunctional N-mustard-containing analogues 15 and 18 are significantly more cytotoxic than the monoalkylating acetamides 11-14. The mustards also exhibited significant activity against cell lines derived from solid tumors such as melanomas, ovarian cancers, CNS cancers, and small cell lung cancer.
Alkylating Agents↗
The effects of a benzoic acid mustard derivative of distamycin A (FCE 24517) and related minor groove-binding distamycin analogues on the activity of major groove-binding alkylating agents.
The distamycin derivative FCE 24517 is a potent antitumour agent. Efforts have been made towards elucidating the mechanism of action of this compound which, to date, have highlighted a high level of DNA sequence specificity for covalent adduct formation. Compared to classical alkylating agents, FCE 24517 forms very few covalent adducts with double-stranded DNA, and thus appears to be a weak alkylating agent. Examination of the effects of this minor groove-binding agent on the major groove of DNA have been facilitated by use of the alkylating agents mustine, melphalan, dabis maleate, quinacrine mustard and uracil mustard. Pretreatment of plasmid DNA with FCE 24517 followed by reaction with any one of these mustards gave rise to a marked abolition of N-7 guanine adduct formation, as assayed by Maxam and Gilbert sequencing gels. The smallest effect was seen for quinacrine mustard, whereas total abolition of N-7 guanine alkylation was seen with uracil mustard. Using related structural analogues of FCE 24517 in the same experiments, it was not possible to reproduce this effect, with very few exceptions. Some effects were seen when using distamycin A itself in these experiments, although these were marginal compared to those seen for FCE 24517. We were able to extrapolate our findings to a whole cell system using murine L-1210 leukaemia cells. Alkaline elution experiments showed that treatment of cultured cells with FCE 24517 followed by either mustine or uracil mustard caused a marked inhibition of DNA interstrand crosslink formation, compared to treatment with mustine or uracil mustard alone. The present study has demonstrated the marked effect that FCE 24517 has upon the reactivity of double-stranded DNA, an effect possibly separate from that of its alkylating function. This study has highlighted the complex nature of the DNA interactive compound FCE 24517 which possess potent and broad spectrum antitumour activity.
Alkylating Agents↗
Establishment of L1210 leukemia cells resistant to the distamycin-A derivative (FCE 24517): characterization and cross-resistance studies.
N-deformyl-N-[4-N,N-bis(2-chloroethylamino)benzoyl] distamycin-A (FCE 24517) is a new cytotoxic anti-tumor agent in phase-1 clinical trials. We have isolated stable FCE-24517-resistant cell sublines from murine leukemia L1210 cells by in vitro exposure to the drug. FCE 24517 selects a mixed population of resistant cells: the L1210/24517(1) cell line in vitro was in fact resistant to the selecting agent (RI 48.3), as well as to L-PAM (RI 5.4) and DX (RI 8.6) and over-expressed the mdr-I gene. When L1210/24517(1) cells were implanted in vivo and evaluated for sensitivity to the same agents, resistance was observed only to FCE 24517 and partially to L-PAM, whereas DX had the same anti-tumor efficacy as on the sensitive line. The clone derived from the above subline (L1210/24517(2)) was resistant to FCE 24517, distamycin-A and other cytotoxic compounds bearing the distamycin-A skeleton, and fully sensitive to DX and other anti-tumor compounds involved in the multi-drug resistance mechanisms, with a complete disappearance of the mdr phenotype. L1210/24517(2) cell line is partially cross-resistant to L-PAM, this resistance being accounted for by higher GSH intracellular levels, which however do not influence the resistance to FCE 24517. In fact, BSO treatment was capable of significantly modifying only the cytotoxicity of L-PAM. Our data suggest that L1210/24517(2) cells present a mechanism of resistance specific for FCE 24517 and related molecules.
Animals↗
Mass spectrometric identification and analysis of some aphidicolin metabolites in cancer patients.
We used gas chromatography/mass spectrometry to identify and quantitate some aphidicolin metabolites in plasma and urine of patients receiving aphidicolin-17-glycinate. The major metabolite found in plasma was 3-ketoaphidicolin, present at about one thent the concentrations of aphidicolin. 3-Ketoaphidicolin undergoes dehydroxymethylation to give 18-nor-3-ketoaphidicolin. This metabolite was also found in plasma and its concentration reached a maximum of 1% of aphidicolin. Small amounts of aphidicolin and 3-ketoaphidicolin were found free in urine but almost all of the drug was conjugated to glucuronic acid, as shown by mass spectrometric analysis of urine extracts and by enzymatic digestion with beta-glucoronidase followed by gas chromatographic/mass spectrometric analysis.
Animals↗
Flow-cytometric measurement of histone H1o in human cells.
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Cell Line↗
A limited sampling model for the pharmacokinetics of etoposide given orally.
A limited sampling model of etoposide after oral administration to estimate the area under the plasma concentration-time curve from 0 to 24 h (AUC) by determination of the drug plasma levels at only two time points was developed by a multiple regression analysis on a training data set of 15 patients receiving oral doses ranging from 54 to 90 mg/m2. The equation describing the model is AUC (micrograms ml-1 h) = 5.183 (micrograms ml-1 h) + 1.193 (h) x C1h (micrograms/ml) + 8.439 (h) x C4h (micrograms/ml) (R2 = 0.93, P = 0.0001), where C1h and C4h represent the plasma etoposide concentrations at 1 and 4 h, respectively. The model was validated prospectively on a test data set of 13 patients receiving oral doses ranging from 52 to 87 mg/m2 and, additionally, on a data set of 7 patients receiving oral doses ranging between 176 and 200 mg/m2, investigated in a previous study. Validation on both test data sets gave a relative mean predictive error of 0.1% and a relative root mean square error of 15.8% and 16.7%, respectively. The present study shows that it is possible to obtain a good estimate of the plasma AUC after oral administration of etoposide using a two-time-point sampling model. The model can be used to monitor the etoposide AUC in patients receiving chronic oral treatment.
Administration, Oral↗
Cis-diamminedichloroplatinum sensitivity of murine reticulum sarcoma cells in primary culture and after in vitro passages.
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Animals↗
Activity and unexpected lung toxicity of the sequential administration of two alkylating agents--dacarbazine and fotemustine--in patients with melanoma.
We report the results and discuss the toxicity of clinical trials based on a single concept: the decrease in O6alkyl DNA alkyltransferase (O6AT) resistance mechanism when a chloroethylating agent is used sequentially after a methylating agent. This decrease in O6AT being dose dependent, several increasing doses of dacarbazine (DTIC) have been tested (400 mg/m2 to 1000 mg/m2 every 4 weeks, 3-4 h before fotemustine (100 mg/m2 intravenously every 4 weeks). These results (mean overall response rate 27%) compared with reference regimes, demonstrate that DTIC is able to increase the alkylating power of fotemustine: same range of response rate with only half of the two drug doses compared to an alternated combination, high activity rate especially in lung metastases (10/42 complete responses + 13/42 partial responses), different pattern for haematotoxicity, and occurrence of a new side-effect: acute lung toxicity as adult respiratory distress syndrome (ARDS). This lung toxicity was totally unexpected since several hundreds of patients had been so far treated with fotemustine as single agent or in other combinations with DTIC without any case of acute or delayed lung toxicity. Prophylactic administration of corticoids was not effective and monitoring of the respiratory function was of no predictive value. Due to the additional depleting effects of DTIC on at least two main defence mechanisms--the O6AT system and cytosolic and/or nuclear glutathione--we suppose that the sequence is able to increase the alkylating power of fotemustine to an excessive extent and/or that the detoxication capacity of the cell against DTIC and/or fotemustine metabolites is overwhelmed. Other depletors of the O6AT activity which do not generate metabolites that compete for the same detoxication pathway as the chloroethylnitrosourea (CENU) metabolites should be tested.
Adult↗
Differential inhibition of the DNA binding of transcription factors NF kappa B and OTF-1 by nitrogen mustard and quinacrine mustard: transcriptional implications.
Nitrogen mustard (HN2) and quinacrine mustard (QM) both inhibited the binding of NF kappa B to the GC-rich consensus sequence in the HIV long terminal repeat (LTR), as assessed by gel-shift assays. QM also inhibited the binding of OTF-1 to the AT-rich octamer present in the H2B promoter whereas HN2 was inactive. Inhibition of the binding of transcription factors was due to the drug interaction with DNA, since it also occurred when transcription factors were added to DNA after removal of free drug. In Jurkat cells transfected with pI3CAT, where the chloramphenicol acetyltransferase (CAT) gene is under the control of the HIV LTR, both HN2 and QM inhibited CAT gene expression. However, in Jurkat cells transfected with plasmid -147, where the CAT gene is under the control of the H2B promoter, QM inhibited CAT expression but HN2 did not. These results were obtained at concentrations of HN2 or QM that inhibited total DNA and RNA synthesis to a similar extent. The present results suggest that the more selective pharmacological activity of HN2 (HN2 is an active antineoplastic agent whereas QM is inactive and very toxic) might be related to its preferential functional inhibition of GC-rich consensus sequence, possibly important in the regulation of genes involved in the malignant proliferation and behavior of some tumors.
Base Composition↗
Lack of bone marrow toxicity of high-dose cyclophosphamide associated with inefficient drug metabolism.
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Agranulocytosis↗
Antitumor activity of taxol (NSC-125973) in human ovarian carcinomas growing in the peritoneal cavity of nude mice.
BACKGROUND: The unique mechanism of action of taxol (NSC-125973) as microtubule stabilizing agent and its potential activity in clinical trials have generated considerable interest in the development of this agent. As taxol was reported to be active on advanced and refractory ovarian carcinomas we focused our studies on the xenograft model of human ovarian carcinoma that develops ascites and tumor dissemination in the peritoneal cavity of nude mice. METHODS: The antitumor activity of taxol was evaluated on two human ovarian carcinoma xenografts (HOC8 and HOC22) transplanted i.p. in nude mice. Drug was given i.v. at doses of 20-34.5 mg/kg every four days three times (Q4 x 3) and the increment of life span (%ILS) was evaluated. Cisplatin at the dosage of 4mg/kg, Q4 x 3 was used as reference drug in each experiment. RESULTS: Taxol given at doses of 20 mg/kg and 34.5 mg/kg to early-stage HOC22 (treatment starting 3 days after tumor transplant) cured all the mice, while the same dose regimens given to advanced HOC22 (treatment starting 14 days after tumor transplant) significantly prolonged the survival time of the mice (ILS = 197% and 300%). Taxol given 3 days after HOC8 transplant significantly prolonged the survival time of tumor-bearing nude mice, inducing complete responses in 50% and 25% of mice receiving, respectively, 34.5 mg/kg/injection and 20 mg/kg/injection. On both ovarian carcinoma xenografts taxol was more active than equitoxic doses of the reference drug cisplatin. CONCLUSIONS: The therapeutic activity against ovarian carcinoma xenografts supports the potential of taxol in the treatment of this neoplasia and forms the basis for future investigations aimed at optimizing the therapeutic activity of taxol given alone or in combination with other drugs.
Animals↗
Low-dose oral etoposide in epithelial cancer of the ovary.
AIMS: To evaluate antitumour activity, toxicity, pharmacokinetics, and the pharmacodynamic relationship with neutropenia of low-dose oral etoposide (E) in patients (pts) with epithelial cancer of the ovary previously treated with cisplatin. PATIENTS AND METHODS: Eighteen pts receiving 50 mg daily of oral E for 21 days every 4 weeks. CBC with differential repeated every week. E plasma levels determined by HPLC method (sensitivity limit: 0.1 microgram/ml) with evaluation during the first cycle of bioavailability and weekly 24-hour drug concentrations. RESULTS: Among 17 evaluable pts, 1 partial remission of 9 months. Dose-limiting neutropenia of high inter-patient variability. Mean bioavailability value of 75%, ranging from 44% to 100%. No correlation between mean 24-hour E plasma levels and ANC nadir or relative decrease of ANC during the first cycle. CONCLUSIONS: Low-dose oral E is ineffective as salvage treatment in epithelial cancer of the ovary. The large variability of neutropenia requires a careful hematological monitoring to avoid severe myelosuppression.
Administration, Oral↗
Chronic oral etoposide in small-cell lung cancer: clinical and pharmacokinetic results.
AIMS: To evaluate antitumour activity, toxicity, pharmacokinetics, and the pharmacodynamic relationship with neutropenia of chronic oral etoposide (E) in patients (pts) with small-cell lung cancer (SCLC) previously untreated with chemotherapy. PATIENTS AND METHODS: Twenty-seven (14 extensive-, 13 limited-stage) pts receiving 100 mg daily of oral E for 21 days every 4 weeks. CBC with differential repeated every week. E plasma levels determined by HPLC method (sensitivity limit: 0.1 microgram/ml) with evaluation during the first cycle of weekly 24-hour drug concentrations. RESULTS: Among 25 evaluable pts, 60% (95% CI: 39%-79%) overall response, 144 and 217 days of median PFS and survival. Dose-limiting non-cumulative neutropenia of high interpatient variability. Linear reduction (30% per week) of absolute neutrophil counts (ANC) up to the 3rd week, recovering the following week. Risk factors for neutropenia (age, PS, serum creatinine and albumin) not identified. High inter-patient variability of 24-hour E plasma levels. A weak correlation between mean 24-hour E plasma levels and ANC nadir or relative decrease of ANC, but higher relative decrease of ANC in pts with 24-hour E plasma levels of > 0.32 microgram/ml. CONCLUSIONS: Chronic oral E is effective in SCLC pts previously untreated with chemotherapy. Careful hematological monitoring is essential to avoid severe myelosuppression. The degree of neutropenia might be related to the maintenance of a critical drug concentration level for a critical period of time.
Administration, Oral↗