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Biomedical subjects

F Zunino

Publications and source records attributed to F Zunino.

At least 163 records · Page 9Linked to original sources
PubMed1990

Different interaction of cisplatin and etoposide on in vivo and in vitro tumor systems.

The effect of cisplatin (CDDP) in combination with etoposide (VP16) was examined on four human cell lines (one colon adenocarcinoma, LoVo; one ovarian carcinoma, IGROV-1; two small cell lung cancers, NCI-H146 and NCI-N592; and two murine leukemias, P388 and L1210). Simultaneous exposure to CDDP and subtoxic concentrations of VP16 for 1 h produced a cell killing in all cell lines comparable to that achieved by CDDP alone. Sequential exposure of NCI-H146 and NCI-N592 to CDDP for 1 h followed by VP16 for 96 h again produced an additive effect. When two of these cell lines were treated in in vivo models (i.p. P388 leukemia, s.c. NCI-N592) with suboptimal doses of the two drugs, a potentiation of the antitumor effects of the two drugs in simultaneous combination was evidenced by the increase in survival time and in the number of 'cures' in P388 leukemia bearing mice and by the inhibition of tumor size in NCI-N592. This comparative study, using the same cell lines in vitro and in vivo, indicates that the CDDP-VP16 potentiation observed in vivo does not reflect a specific interaction at the cellular-biochemical level. The results support the therapeutic interest of this combination (presumably as a result from favorable pharmacological interactions) even despite the lack of potentiation at cellular level, under comparable conditions of treatment.

Animals↗
PubMed1990

Effect of tumor necrosis factor on human tumor cell lines sensitive and resistant to cytotoxic drugs, and its interaction with chemotherapeutic agents.

We investigated the cytotoxic effects of recombinant tumor necrosis factor (TNF) alone and in combination with interferon-gamma (IFN-gamma) and/or cytotoxic drugs on a variety of human tumor cell lines (U937, IGROV-1, HT29, LoVo, MCF7 and U20S), including cell lines with in vitro acquired resistance (LoVo/DX and MCF7/DX selected for resistance to doxorubicin (DX) and characterized by pleiotropic drug resistance; U20S selected for resistance to cisplatin (CDDP], using MTT assay. U937 and MCF7 were sensitive to the cytotoxic effect of TNF, whereas all the other cells were insensitive up to 1000 U/ml (the maximum tested dose). Surprisingly, TNF was cytotoxic (30-40% cytotoxicity) against two resistant lines (LoVo/DX and U20S/Pt) but not against the parent sensitive lines. Treatment with increasing doses of TNF after 6 h incubation with a subtoxic concentration of IFN-gamma produced a synergistic effect in four cell lines (U937, HT29, LoVo/DX and MCF7), whereas in the other five the cell killing of the combination was comparable with that achieved by TNF alone. The combination of subtoxic doses of TNF and increasing doses of drugs targeted at DNA topoisomerase II (i.e. DX, actinomycin D and VP16) produced an additive cytotoxic effect in all cell lines. The same results were obtained combining TNF and CDDP, except in U20S/Pt cells in which TNF synergistically increased CDDP cytotoxicity. The combination of TNF and IFN-gamma enhanced cytotoxicity about 20-fold for DX and 6-fold for CDDP, evaluated in terms of the modification index, against LoVo/DX and U20S/Pt cells respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Agents↗
PubMed1990

Effect of glutathione and N-acetylcysteine on in vitro and in vivo cardiac toxicity of doxorubicin.

The effects of two sulfhydryl compounds, glutathione (GSH) and N-acetylcysteine (NAC), on the cardiotoxicity of doxorubicin (DXR) were tested on in vitro and in vivo models. DXR was administered to rats as 4 weekly i.v. doses of 3 mg/kg. GSH (1.5 mmoles/kg), given i.v. 10 min before and 1 hr after DXR, was found to prevent the development of the delayed cardiotoxic effects of DXR, as assessed by electrocardiographic and mechanical parameters, as well as by histological examination of left ventricular preparations. In contrast, equimolar oral doses of NAC (1 hr before and 2 hrs after DXR) were found to be ineffective. Both GSH and NAC prevented the negative inotropic effect produced by DXR on isolated rat atria. A good correlation exists between the cardioprotective effects of the two agents and their ability to enhance the non-protein sulfhydryl group content of the myocardium. Differences observed in vivo between GSH and NAC might be accounted for by pharmacokinetic factors.

Acetylcysteine↗
PubMed1990

DNA topoisomerase II as the primary target of anti-tumor anthracyclines.

Recent structure-activity relationship studies emphasize the critical role of topoisomerase II-mediated DNA cleavage on the cytotoxic activity of anthracycline anti-tumor antibiotics. Such studies have also given evidence of the peculiar features of the drug interference with DNA topoisomerase II activity. In contrast to other cytotoxic topoisomerase II inhibitors (acridines, epipodophyllotoxins), anthracyclines produce persistent DNA cleavable complexes. This property is more evident with doxorubicin derivatives than with daunorubicin derivatives. The strength of DNA binding apparently does not correlate with the stimulatory effect of anthracyclines on topoisomerase II-mediated DNA cleavage and with their cytotoxic potency. However, drug intercalation is still required for optimal drug activity. Such an observation suggests that the specific mode of DNA interaction, rather than the strength of binding, is important in determining the cytotoxic potency. The extent of anthracycline-induced cleavage results from a balance between a stimulation and a suppressive effect of the drug on topoisomerase II DNA cleavage. Anthracyclines are sequence selective in the induction of DNA cleavage by purified topoisomerase II. Despite the extensive effort in developing DNA intercalating agents as anti-tumor drugs, the limited success of such an approach could be rationalized in terms of the still inadequate 'rational design', since the molecular basis of specific drug-DNA topoisomerase II interaction (e.g. sites of cleavage, cell response to DNA damage, etc.) is not completely understood. Such studies indicating structural requirements in anthracycline molecules, which are critical for specific drug interference with topoisomerase II functions, provide the opportunity to re-examine the mechanism of action of these agents and to design new, more selective derivatives.

Animals↗
PubMed1990

Evidence of DNA topoisomerase II-dependent mechanisms of multidrug resistance in P388 leukemia cells.

A multidrug-resistant variant of the P388 leukemia cell line exhibits multiple biochemical changes, including reduced drug accumulation and markedly reduced DNA strand breakage induced by anthracyclines. To investigate whether the reduced formation of drug-induced DNA breaks was due to alteration of DNA topoisomerase II activity, nuclear extracts and partially purified enzymes from the sensitive line and the resistant subline were compared. DNA topoisomerase II activity in 0.35 M NaCl nuclear extracts from sensitive cells was approximately 1.7 times higher than that found in extracts from resistant cells, as determined by ability to unknot P4 phage DNA. In addition, it was found that teniposide-stimulated topoisomerase II DNA cleavage activity of nuclear extract from resistant cells was at least 10-fold lower than that from sensitive cells. This differential sensitivity paralleled a similar drug response of nuclei, as determined by the alkaline elution method. However, partially purified DNA topoisomerase II showed similar drug sensitivity in both cell lines. This finding suggests the presence of a modulating factor, which may be lost during purification. These results, indicating a reduction of both catalytic activity and DNA cleavage activity of DNA topoisomerase II in P388 multidrug-resistant cells, emphasize the importance of DNa topoisomerase function in the resistance mechanism. Thus, the concomitant involvement of multiple mechanisms could explain the high degree of resistance of these cells.

Adenosine Triphosphate↗
PubMed1989

Changes in the three-dimensional organization of LoVo cells associated with resistance to doxorubicin.

LoVo cells and a derived subline resistant to doxorubicin were compared in the spheroids system. The resistant line, unlike the parent one, was unable to grow as spheroids, but formed irregular loose aggregates. Moreover treatment of the resistant cells with membrane-active agents able to reverse pleiotropic drug resistance had no effect on the capability of these cells to grow as spheroids. The results indicate that the inability of resistant cells to form spheroids is not related to the resistance mechanism.

Adenocarcinoma↗
PubMed1989

Protein kinase C activation and lipid peroxidation by doxorubicin analogues.

Several doxorubicin analogues have been tested for their capacity to activate protein kinase C (PKC) and to induce lipid peroxidation in intact human platelets. Only doxorubicin and 4'-iodo-doxorubicin were able to induce lipid peroxidation and PKC activation the first being the most effective. N-acetyldoxorubicin, N-trifluoroacetyl-doxorubicin-14-valerate (AD32) and doxorubicin-14-propionate were not effective on either event. This correlation supports that PKC activation in human platelets by doxorubicin is mediated by lipid peroxidation and suggests that the effect is specific for anthracyclines with a doxorubicin aglycone and a free charged amino group in the sugar moiety. The results stress the new action of anthracyclines, whose pharmacologic implications are presently under investigation on nucleated cells.

Doxorubicin↗
PubMed1989

A preliminary clinical study of cyclophosphamide with reduced glutathione as uroprotector.

Reduced glutathione (GSH) has been reported to be an effective protector against cyclophosphamide-induced urotoxicity in experimental models, providing protection comparable to that of mesna. This paper describes our preliminary results of the clinical use of GSH in combination with cyclophosphamide. GSH was administered i.v. in two divided doses of 2.5 g, 15 min before and 30 min after escalating doses of cyclophosphamide ranging from 1.2 up to 1.6 g/m2 (1-h infusion). GSH was well tolerated and did not produce unexpected toxicity. The lack of bladder damage, including microscopic hematuria, supports the protective role of this thiol compound.

Adult↗
PubMed1989

Role of DNA breakage in cytotoxicity of doxorubicin, 9-deoxydoxorubicin, and 4-demethyl-6-deoxydoxorubicin in murine leukemia P388 cells.

Formation and persistence of DNA single- and double-strand breaks stimulated by doxorubicin, 9-deoxydoxorubicin, or 4-demethyl-6-deoxydoxorubicin in murine leukemia P388 cells were compared in relation to drug DNA affinity, cellular pharmacokinetics, and cytotoxicity. Although cellular uptake and retention and DNA affinity of the anthracycline derivatives were similar to those of the parent drug, cytotoxic potency was quite different, 9-deoxydoxorubicin being much less cytotoxic than doxorubicin, and 4-demethyl-6-deoxydoxorubicin the most effective agent. After 1-h exposure of cells to cytotoxic drug levels, the extent of DNA strand breaks produced by 4-demethyl-6-deoxydoxorubicin was greater than that produced by doxorubicin, whereas 9-deoxydoxorubicin induced very few DNA breaks. As for the parent drug, proteolytic treatment of cell lysates on the filter was needed to detect DNA cleavage produced by the analogues. A linear increase of DNA breaks was observed for 2 h following 4-demethyl-6-deoxydoxorubicin or doxorubicin addition; by contrast, DNA break levels reached a plateau after 45 min of exposure to 9-deoxydoxorubicin. DNA lesions produced by the derivatives persisted, and doxorubicin-induced DNA breaks even increased after drug removal, indicating an absence of DNA break resealing under our conditions. These observations indicate that modifications of the chromophore moiety of the anthracycline may enhance both drug cytotoxicity and specificity of drug-target interactions, and thus provide further strong evidence that the anthracycline effect on DNA integrity is a critical aspect of the mechanism of drug action.

Animals↗
PubMed1989

Effects of 5-FU and cis-DDP combination on human colorectal tumor xenografts.

The antitumor efficacy of the cis-diamminedichloroplatinum (cisDDP) and 5 fluorouracil (5FU) combination was evaluated in a panel of eight human colorectal carcinoma xenografts. Tumors differed in origin (primary or metastatic), differentiation degree and chemotherapy treatment. Xenografts were treated with repeated i.v. injections of cisDDP, 5FU, or both drugs at 24-h interval. Compared with controls, cisDDP achieved a significant tumor growth inhibition in five out of eight tumor lines, and 5FU in four out of seven. One of two unresponsive tumor lines was significantly inhibited by the combination, that was also more effective than either drug alone (p less than 0.05) in one responsive xenograft. Comparing the effects of the combination according to which drug was administered first, lower drug doses were tolerated using the cisDDP-5FU sequence, but the antitumor effects were similar at equitoxic doses. These results indicate a potential therapeutic benefit of the cisDDP-5FU combination for colorectal carcinoma patients and show that toxicity of the combination is influenced by the drug sequence.

Adult↗
PubMed1989

Formation, resealing and persistence of DNA breaks produced by 4-demethoxydaunorubicin in P388 leukemia cells.

The formation and disappearance of DNA single-strand breaks (SSB) produced by 4-demethoxydaunorubicin (4-dmDR) in P388 murine leukemia cells and in a resistant subline were examined by alkaline elution methods in relation to cellular pharmacokinetics. DNA strand breaks produced by this intercalating agent were essentially DNA lesions mediated by topoisomerase II, even at very high drug concentrations, since they were detected as protein-associated breaks by filter elution. Similarly, the appearance of delayed DNA breaks in cells exposed to high concentrations, following drug removal, showed predominance of protein-associated breaks, thus supporting a similar mechanism of breakage induction. This finding indirectly suggests that, in this experimental model, free radical production makes little (if any) contribution to DNA damage, and also that DNA effects are not the consequence of early cell death. In contrast to a rapid disappearance of protein-associated strand breaks produced by intercalating agents and topoisomerase II inhibitors of different classes, DNA breaks induced by low concentrations of the anthracycline derivative are only partially reversible following drug removal, but they persisted and even increased with high concentrations. Thus, not only the extent of DNA breaks but also their persistence may contribute to the cytotoxic potency of anthracyclines. The importance of DNA lesions to cytotoxic action of the anthracycline is also emphasized by drug effect on the resistant line. A negligible effect on DNA of resistant cells was detected at drug concentrations lethal to sensitive cells. However, exposure to equitoxic drug concentrations resulted in a comparable amount of DNA breaks in sensitive and resistant cells. Although faster DNA rejoining in resistant cells may be in part attributable to increased efflux of drug, no correlation exists between cell drug accumulation and extent of DNA lesions. With equitoxic drug concentrations cellular drug content was higher in resistant cells, suggesting an intrinsic insensitivity of this variant to DNA cleavage effects of the anthracycline.

Animals↗
PubMed1989

Protective effect of reduced glutathione against cisplatin-induced renal and systemic toxicity and its influence on the therapeutic activity of the antitumor drug.

Reduced glutathione has been shown to be an effective protector against cisplatin-induced nephrotoxicity of potential clinical value, since it does not reduce antitumor activity of the cytotoxic drug. This paper extends previous observations on the protective potential of reduced glutathione against cisplatin-induced nephrotoxicity, in different rodent models. Following i.v. administration, glutathione protection against cisplatin-induced nephrotoxicity was found to be critically dependent on timing of thiol administration. Whereas the sulfhydryl compound provided almost complete protection in CD rats, the protective effect against toxic renal damage was only partial in mice of different strains. In spite of the modest protection against kidney toxicity, glutathione reduced lethal toxicity in the mouse. Under the same experimental conditions at protective dose levels, the tripeptide thiol did not interfere with the antitumor effectiveness of cisplatin, in any of the tumor models examined. The kidney content of non-protein sulfhydryls of CD rats produced by the effective dose of glutathione was markedly higher than that found in the mouse treated with the same dose. This finding is consistent with a differential protection provided by glutathione against cisplatin-induced renal toxicity in these species.

Animals↗
PubMed1989

P-glycoprotein gene amplification and expression in multidrug-resistant murine P388 and B16 cell lines.

P-glycoprotein gene (mdrl) amplification and expression were examined in murine leukaemia P388/DX and melanoma B16VDXR cell lines, which exhibit a high level of resistance to a selecting agent, doxorubicin, and express a multidrug-resistant phenotype because they are cross-resistant to multiple cytotoxic drugs. The multidrug-resistant phenotype was obtained in different conditions of selection (in vivo and in vitro for P388/DX and B16VDXR, respectively). In both multidrug-resistant cell lines, an increased expression of P-glycoprotein gene (5 kb transcript detected in Northern blots) was observed and the level of P-glycoprotein mRNA correlated with the degree of resistance. In addition, high molecular weight mRNAs homologous to mdrl gene sequence were consistently detected only in P388/DX cells. Overexpression was associated with a high level of gene amplification only in resistant melanoma cells, whereas it occurred in P388/DX cells with a marginal increase in gene copy number. These results, suggesting that different genetic mechanisms could be responsible for P-glycoprotein overexpression, emphasise the complexity of genetic regulation that may affect tumour cell sensitivity to cytotoxic agents.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1988

Sequence dependence of the antitumor and toxic effects of 5-fluorouracil and cis-diamminedichloroplatinum combination on primary colon tumors in mice.

Primary colon tumors of different sizes and malignancy, chemically induced by methylazoxymethanol in outbred CF-1 mice, were used to investigate the antitumor effects of 5-Fluorouracil (5FU) and cis-diammine-dichloroplatinum (DDP), given weekly i.v. as single agents or in combination. When single-drug chemotherapy was tested, DDP showed higher efficacy than 5FU. In fact, in two separate experiments a significant reduction (P less than 0.05) of tumor number (TN) and tumor burden was obtained by treatment with the optimal dose of DDP (4.5 mg/kg per injection) and not by that of 5FU (52 mg/kg). When the two drugs were combined (24-h interval), studies carried out on healthy mice treated weekly i.v. showed a lower toxicity with the same doses given in the sequence 5FU-DDP than in the opposite sequence. The two drugs, delivered in the sequence 5FU followed by DDP, statistically reduced the TN and total tumor burden compared to control mice (P less than 0.05). On the other hand, the same doses in the sequence DDP followed by 5FU did not attain significant tumor reduction. The sequence dependence of the activity and toxicity of the 5FU and DDP combination observed in this experimental model should be taken into account in the design of clinical trials.

Animals↗
PubMed1987

In vitro and in vivo studies of poly-L-lysine as inducer of Friend leukemic cells differentiation.

Poly-L-lysine, a synthetic cationic polypeptide known for its ability to bind to cell membranes, was found to induce differentiation of Friend leukemia cells "in vitro". Studies were extended to the same "in vitro" model, in order to examine the therapeutic potential of this new differentiating agent. The i.p. administration of the polymer (Mw 2700) at the maximal tolerated dose resulted in major alterations of disease-related parameters. In particular, a multiple treatment schedule on the advanced disease resulted in a successful reduction of target organ weight and peripheral white blood cell count and appreciable differentiation of spleen and bone marrow cells. Apparently, the effects of poly-L-lysine were superior to those produced by N-methyl-acetamide, a potent inducer of differentiation "in vitro".

Acetamides↗
PubMed1987

A preliminary clinical experience with reduced glutathione as protector against cisplatin-toxicity.

A total of 16 consecutive patients (15 with ovarian cancer and 1 with unknown adenocarcinoma) were treated with a standard regimen including cisplatin and cyclophosphamide or with the same regimen in combination with reduced glutathione as potential protective agent against cisplatin nephrotoxicity, in a non-randomized study. Reduced glutathione (1500 mg/m2) was administered prior to each cisplatin administration (90 mg/m2) to seven patients for a maximum of five consecutive courses. A standard hydration protocol without diuretics was used. The patients received a total of 33 courses with glutathione. Glutathione was well tolerated, since it did not produce appreciable side effects. Cisplatin and glutathione combination did not produce unexpected toxicity. Two patients treated with standard regimen without glutathione developed a transient nephrotoxicity. The severity of myelosuppression was reduced following glutathione administration. Moreover, the therapeutic efficacy was not impaired by glutathione pretreatment.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Markedly reduced levels of anthracycline-induced DNA strand breaks in resistant P388 leukemia cells and isolated nuclei.

DNA single-strand and double-strand breaks produced by doxorubicin and two anthracycline derivatives (4-demethoxy-daunorubicin and 4'-deoxy-4'-iododoxorubicin) were measured in doxorubicin-sensitive and -resistant P388 leukemia cell lines, using filter elution methods, and compared with cellular drug accumulation to account for major differences in their cytotoxic activities and cross-resistance. The increased cytotoxic potency of the two derivatives reflects at least in part the enhanced drug accumulation by cells that results from their increased lipophilicity. However, the level of protein-linked DNA breaks was not directly related to cellular accumulation of drug analogues. It is possible that enhanced cytotoxicity may also be the consequence of the greatly enhanced ability of analogues to cause DNA strand breaks. The resistant line showed only a modest degree of resistance to both anthracycline derivatives compared with the high degree of resistance to doxorubicin. Although for all the anthracyclines tested drug accumulation was reduced in the resistant line, this did not correlate with the degree of resistance. A differential sensitivity of resistant and parental cell lines to DNA cleavage activity was consistently found for all three drugs tested. However, in contrast to a lack of effect of doxorubicin, the derivatives caused appreciable DNA strand breakage in resistant cells. The enhanced ability of these analogues to break DNA in resistant cells is consistent with the slight cross-resistance with doxorubicin. DNA double-strand breaks produced in isolated nuclei from these cells paralleled the pattern found in whole cells, thus indicating that a nuclear alteration, presumably involving DNA topoisomerases, is associated with anthracycline resistance. Our findings strongly support the hypothesis that anthracycline resistance in these cell variants may be mediated by multiple mechanisms, involving alterations of plasma membrane and changes of nuclear enzymatic activities responsible for DNA strand breaks.

Animals↗