Effect of Withania somnifera on cyclophosphamide-induced urotoxicity

Administration of an extract from the plant Withania somnifera (Family: Solanaceae) (20 mg/dose/animal; i.p.) for five days along with cyclophosphamide (CTX) (1.5 mmol/kg body wt. i.p.) reduced the CTX induced urotoxicity. Morphological analysis of the bladders of the CTX-treated group showed severe inflammation and dark coloration whereas CTX along with the Withania-treated group showed normal bladder morphology. The extract was found to reduce the protein level in the serum (7.92 g/l) after 4 h of CTX treatment, which was higher in the CTX alone-administered group (11.44 g/l). Blood urea N2 level which was drastically enhanced (136.78 mg/100 ml) 2 after the CTX treatment was significantly reduced (52.08 mg/100 ml) when the animals were treated with Withania extract. Similarly the glutathione (GSH) content in both bladder (1.55 micromol/mg protein) and liver (3.76 micromol/mg protein) was enhanced significantly (P<0.001) in the Withania-treated group compared with the CTX alone-treated animals (bladder 0.5 micromol/mg protein; liver 1.2 micromol/mg protein) Histopathological analysis of the bladder of CTX alone-treated group showed severe necrotic damage where as the Withania somnifera-treated group showed normal bladder architecture.

Stobadine inhibits lysosomal enzyme release in vivo and in vitro

This study investigated the ability of stobadine, an effective cardioprotective drug with antiarrhythmic, antihypoxic and oxygen free radical scavenging properties, to protect cells against cyclophosphamide-induced toxic and cytotoxic damage in vivo and in vitro. Cyclophosphamide-induced toxic damage in female ICR mice was accompanied by marked increase in the activity of lysosomal enzymes in the spleen and kidney. Administration of stobadine prior to cyclophosphamide inhibited these biochemical changes. The in vivo protective effect of stobadine was comparable with its in vitro effect established in HeLa cells.

Effects of GSH and WR-2721 on induction of micronuclei by cyclophosphamide

The frequency of micronucleated polychromatic erythrocytes (MNPCEs) was assessed in the bone marrow and peripheral blood of adult male Swiss mice treated with reduced glutathione (GSH) and/or S-2-/3-aminopropylamino/ethyl phosphorothioic acid (WR-2721), at a dose of 400 mg/kg body weight, and/or with cyclophosphamide (CP), at a dose of 200 mg/kg body weight. GSH was given 60 or 15 min and/or WR-2721 was applied 30 min before CP administration. The number of MNPCEs was determined at 24 h after the drug application. After treatment of mice with CP, the frequency of MNPCEs was distinctly increased. The stronger chemoprotective effect against CP-induced cytotoxicity was obtained following GSH administration than after WR-2721 injection. WR-2721 characterized greater cytotoxicity than GSH. The combination of GSH and WR-2721 given alone, or before CP administration resulted in the most cytotoxic and chemoprotective effects, compared with the respective single-thiol treatment of mice. The most effective protection against CP-induced genotoxicity was observed in the case of treatment of mice with WR-2721and GSH, respectively, 30 and 15 min before CP administration. The most cytotoxic effect of the thiols was found when GSH given 30 min prior to WR-2721 application. The chemoprotection and cytotoxicity caused in the mouse erythroblasts by GSH and WR-2721, as indicated by the number of MNPCEs were dependent on the thiol(s) given, and the time intervals between the drug administration. The modulatory effect of the thiols GSH and WR-2721 on 'delayed apoptosis' induced in the erythropoietic system by cyclophosphamide was shown.

Protective effect of the antioxidant stobadine against cyclophosphamide and irradiation induced oxidative stress

The antioxidant stobadine was tested for its efficiency against oxidative stress in model experiments with ICR nonpregnant mice exposed either to cyclophosphamide (80 mg/kg) or whole body 60Co (6.5 Gy) irradiation. In a teratological experiment, pregnant mice were exposed to cyclophosphamide (10 mg/kg) from day 11 to 17 of gestation. Toxicity was measured by determining the lysosomal enzymes acid phosphatase and N-acetyl-beta-D-glucosaminidase. Cyclophosphamide and irradiation caused a significant increase in acid phosphatase and N-acetyl-beta-D-glucosaminidase activity in the spleen of nonpregnant mice. In the liver, lysosomal enzyme activities were unchanged and no changes in protein levels were recorded. In pregnant mice, acid phosphatase and N-acetyl-beta-D-glucosaminidase activities were increased in the spleen. An increase in foetal acid phosphatase liver activity was found. Pretreatment with stobadine prior to cyclophosphamide and irradiation significantly diminished the biochemical changes in both nonpregnant and pregnant mice. We conclude that stobadine is able to protect mice against cyclophosphamide- or irradiation-induced oxidative stress.

Anticlastogenic effects of centchroman and its enantiomers in Swiss albino mice. I. Acute study and their comparison with tamoxifen

Centchroman (CC), a non steroidal oral contraceptive and a candidate drug for breast cancer, has been reported to exhibit partial to complete remission of lesions in 40.5% of breast cancer patients. Recently, we have reported the antimutagenic effects of CC in multiple mutational assays. The potent antioestrogenic activity, negligible side effects, anti-breast cancer activity and antimutagenic effects of CC prompted us to evaluate the anticlastogenic effects of CC and two of its enantiomers. i.e. D-centchroman (DC) and L-centchroman (LC) in the acute in vivo studies in female Swiss albino mice as measured by chromosome aberrations (CA) and sister chromatid exchange (SCE) assays against two known positive mutagen compounds, i.e. dimethylbenz[a]anthracene (DMBA) and cyclophosphamide (CP). The results of anti-mutagenicity assays of CC and its enantiomers have been compared to the known breast cancer drug tamoxifen (TM). CC and LC reduced both DMBA and CP induced CA when compared with the group treated with only DMBA and CP. DC did not reduce the DMBA-induced CA when compared with the DMBA-treated group alone. It reduces only the CP induced CA. TM also reduces both DMBA and CP induced CA when compared with group received only DMBA or CP. SCE were carried out only for LC. A weak but significant decrease in SCE was observed in both LC plus DMBA- and LC plus CP-treated groups when compared with respective positive controls alone. Thus the overall results indicate that both CC and LC are more effective in reducing the genotoxic effects of DMBA and CP than DC.

[Effect of total diterpene of Rabdosia macrocalyx on mice of normal and immunosuppression]

OBJECTIVE

The regulatory effects of total diterpene of Rabdosia macrocalyx (Dunn) Hara on immune function were studied.

METHODS

The experimental immunosuppressive mouse models were induced by injection of cyclophosphamide.

RESULTS

The index of thymus gland and spleen in normal and immunosuppressive mice were increased significantly. So were the level of hemolysin in serum when 50 mg/kg total diterpene were given. Delayed hypersensivity were also enhanced at the same condition. But there didn't show any change in carbon clearance test.

CONCLUSION

Total diterpene of Rabdosia macrocalyx (Dunn) Hara possesses obvious regulatory action on immune function in mice.

Development of a substrate-activity based approach to identify the major human liver P-450 catalysts of cyclophosphamide and ifosfamide activation based on cDNA-expressed activities and liver microsomal P-450 profiles

The contributions of specific human liver cytochrome P-450 (CYP) enzymes to the activation, via 4-hydroxylation, of the oxazaphosphorine anticancer prodrugs cyclophosphamide (CPA) and ifosfamide (IFA) were investigated. Analysis of a panel of 15 human P-450 cDNAs expressed in human lymphoblasts and/or baculovirus-infected insect cells (Supersomes) demonstrated that CYPs 2A6, 2B6, 3A4, 3A5, and three CYP2C enzymes (2C9, 2C18, 2C19) exhibited significant oxazaphosphorine 4-hydroxylase activity, with 2B6 and 3A4 displaying the highest activity toward CPA and IFA, respectively. CYP2B6 metabolized CPA at a approximately 16-fold higher in vitro intrinsic clearance (apparent Vmax/Km) than IFA, whereas 3A4 demonstrated approximately 2-fold higher Vmax/Km toward IFA. A relative substrate-activity factor (RSF)-based method was developed to calculate the contributions of individual P-450s to total human liver microsomal metabolism based on cDNA-expressed P-450 activity data and measurements of the liver microsomal activity of each P-450 form. Using this method, excellent correlations were obtained when comparing measured versus predicted (calculated) microsomal 4-hydroxylase activities for both CPA (r = 0. 96, p <.001) and IFA (r = 0.90, p <.001) in a panel of 17 livers. The RSF method identified CYP2B6 as a major CPA 4-hydroxylase and CYP3A4 as the dominant IFA 4-hydroxylase in the majority of livers, with CYPs 2C9 and 2A6 making more minor contributions. These predicted P-450 enzyme contributions were verified using an inhibitory monoclonal antibody for 2B6 and the P-450 form-specific chemical inhibitors troleandomycin for 3A4 and sulfaphenazole for 2C9, thus validating the RSF approach. Finally, Western blot analysis using anti-2B6 monoclonal antibody demonstrated the presence of 2B6 protein at a readily detectable level in all but one of 17 livers. These data further establish the significance of human liver CYP2B6 for the activation of the clinically important cancer chemotherapeutic prodrug CPA.

Ultrasonic depolymerization of the chitin-glucan complex from Aspergillus niger and antimutagenic activity of its product

Sonication was effective for the depolymerization of carboxymethylated chitin-glucan complex (CM-CG) isolated from the cell wall of Aspergillus niger. After 10 min of sonication and subsequent gel filtration, two samples (CM-CG(I) and CM CG(II)) with significantly distinct molecular weights (660 kDa and 19 kDa, respectively) and different nitrogen contents (3.02 and 1.69%) were obtained. CM-CG(II) with lower Mw was also effective against cyclophosphamide mutagenicity by oral administration in mice.

Inhibitory action of melatonin on H2O2- and cyclophosphamide-induced DNA damage

Melatonin, the pineal gland hormone known for its ability to modulate circadian rhythm, has recently been studied in its several functions. It is believed to inhibit cancer growth, to stimulate the immune system and to act as an antioxidant. In particular, this latter activity is ascribed to two different mechanisms: stimulation of radical detoxifying enzymes and scavenging of free radicals. We used this compound in mammalian cells in vitro to investigate its mechanism of action in modulating DNA damage. Cytogenetic and cytofluorimetric analyses were performed. We show that melatonin is able to modulate chromosome damage (chromosomal aberrations and sister chromatid exchanges) induced by cyclophosphamide. Conversely, its involvement in modulating oxidative processes, thereby reducing DNA damage, is less clear. In particular, melatonin is able to decrease H2O2-induced chromosomal aberrations but not sister chromatid exchanges and has been found to induce oxygen species in a cytofluorimetric test (DCFH assay).

Prevention of cyclophosphamide-induced micronucleus formation in mouse bone marrow by indole-3-carbinol

Indole-3-carbinol (I3C) is a glucobrassicin derivative isolated from cruciferous vegetables. In this study, the protective effect of 13C is reported against cyclophosphamide (CP)-induced micronuclei formation in mouse bone marrow cells. The three test doses, namely 500, 250 and 125 mg/kg body weight of 13C provided protection when given 48 hr prior to the single ip administration of cyclophosphamide (50 mg/kg). The efficacy of the test doses of 13C was also evaluated using a lower dose of CP (25 mg/kg body weight). A significant inhibition in micronuclei formation was noticed with 13C at 250 and 125 mg/kg body weight dose. 13C could not induce micronuclei formation at the test doses 500 and 250 mg/kg body weight. 13C, therefore seems to have a preventive potential against CP-induced micronuclei formation in Swiss mouse bone marrow cells.

Protective effects of fruits and vegetables against in vivo clastogenicity of cyclosphosphamide or benzo[a]pyrene in mice

Seven fruits and 10 vegetables commonly consumed in Germany were investigated for their anticlastogenic potencies against cyclophosphamide (CP) and benzo[a]pyrene (BaP) in the in vivo mouse bone marrow micronucleus assay. We detected protective effects in 76.5% and 70.6% of the samples, respectively, and more or less distinct quantitative differences between the various plant materials and the two clastogens investigated. With respect to CP, moderate activities were exerted by sweet cherries, strawberries, cucumber, radish and tomatoes, average activities by bananas, oranges, peaches, asparagus and red beets and strong activities by yellow red peppers and especially spinach. Apples (cultivar Jona Gold), brussels sprouts, cauliflower and onions were inactive. With respect to BaP, we found moderate activities in strawberries, brussels sprouts and radish, average activities in sweet cherries, oranges, peaches, asparagus, red beets, cucumber and spinach and strong activities in bananas and kiwi. Apples, cauliflower, onions, tomatoes and yellow-red peppers were inactive. When oranges were fractionated according to previously described schemes (Edenharder et al., 1995), anticlastogenic activities against CP were exerted by materials extracted with n-hexane, acetone and 2-propanol and in the terminal residue, but not in the dichloromethane and water phases. With respect to BaP, materials extracted with acetone showed strong anticlastogenicity while the 2-propanol fraction, the aqueous phase and the terminal residue were less potent. The n-hexane and the dichloromethane fractions were inactive. In red beets, all fractions showed anticlastogenicity against CP and BaP as well. However, the n-hexane and dichloromethane fractions were most potent with respect to CP, while for BaP the aqueous phase and the terminal residue were most effective. These result suggest the presence of various (groups of) anticlastogenic compounds with different chemical structure.

[The influence of melatonin on mutagenicity and antitumor action of cytostatic drugs in mice]

SHR mice received single injections of N-nitrosomethylurea (NMU, 50 mg/kg, i.p.), cyclophosphamide (CP, 200 mg/kg, i.p.) or 1,2-dimethylhydrazine (DMH, 15 mg/kg, s.c.) alone or in combination with melatonin (5 mg/kg, s.c.). For mutagenic study chromosome aberrations tests (ChA) in bone marrow cells and sperm head anomaly test (SHA) were used. Melatonin did not appear mutagenic in either of the tests and significantly reduced the level of ChA (%) from 16.9 +/- 1.6 (NMU), 13.7 +/- 3.5 (CP) and 8.7 +/- 0.3 (DMH) to 4.5 +/- 0.6, 4.3 +/- 0.9 and 5.6 +/- 0.2, respectively, (p < 0.05). Similarly, SHA frequency (%) under the melatonin influence was reduced from 18.6 +/- 0.4 (NMU), 17.7 +/- 0.4 (CP) and 10.0 +/- 0.5 (DVH) to 9.9 +/- 0.5, 6.1 +/- 0.3 and 7.5 +/- 0.2, respectively, (p < 0.05). Unlike in controls, exposure to melatonin in drinking water (20 mg/l, at night) or in injections (5 mg/kg, s.c.) alone or in combination with NMU or CP failed to influence subcutaneously-transplanted Ehrlich carcinoma growth. These findings suggest that melatonin reduced the mutagenicity of the cytostatic drugs without affecting their anti-tumor action.

[Anti-injure effect of extract from orange (EOP) peel on germ cells of male mice]

In present study, the anti-injure effect of EOP, on incidence of sperm abnormality and meiotic micronuclei of early spermatids in mice induced by cyclophosphamide was investigated. The results indicated that EOP itself was not a mutagen, but significantly inhibited increase of the rate of micronuclei and the sperm abnormality by CP. The rates of sperm abnormality and meiotic micronuclei of early spermatide of EOP before CP using group were lower obviously than those of CP could before EOP using group (P < 0.01). The results suggested that the CP could permeate blood-testis barrier into germ cells of male mice and induced mutation on genetic material.

Studies on the anticlastogenic effect of turmeric and curcumin on cyclophosphamide and mitomycin C in vivo

Turmeric and its main constituent curcumin were assessed in vivo for their anticlastogenic potential. In one experimental set, Swiss albino male mice were given turmeric (8, 12 and 16 mg/kg body weight) or curcumin (2, 4 and 8 mg/kg body weight) as a single intraperitoneal injection. In another set, the mice were given 8 mg/kg body weight of turmeric or one of three concentrations of curcumin (2, 4 and 8 mg/kg body weight) as a dietary supplement by gavage for 7 consecutive days. 30 min after the last dose the mice were administered a single acute dose of two known clastogens, cyclophosphamide (CP) (20 mg/kg body weight) or mitomycin C (MMC) (1.5 mg/kg body weight). After 18 hr, chromosome preparations were made from bone marrow cells. The endpoints studied were chromosome aberrations and damaged cells. Clastogenicity of the chemicals was compared using turmeric- or curcumin-primed and non-primed animals. As single agents turmeric and curcumin were not clastogenic even after 7 days of priming. Turmeric/curcumin could not inhibit CP- or MMC-induced clastogenicity. Although curcumin is reported to be the active chemopreventive principle in turmeric effective against a number of potential carcinogens in several experimental systems, it was virtually ineffective against the clastogenicity of CP or MMC at the doses tested.

The influence of two carotenoid food dyes on clastogenic activities of cyclophosphamide and dioxidine in mice

The influence of the food dyes E160e (beta-apo-8'-carotenal in an oil suspension) and E160a (beta-carotene in an oil suspension) on clastogenic effects of cyclophosphamide (CP) and dioxidine (DN) was investigated. Chromosome damage in the bone marrow of C57BL/6 mice was reported. The following protocols were used: (1) simultaneous single administration of the dye and the mutagen and the subsequent animal sacrifice within 24 hr; (2) a 4-day pretreatment with the dye (daily administrations) followed with simultaneous injection of the dye and the mutagen on the 5th day 24 hr before sacrifice; (3) daily co-administration of the dye and the mutagen for 5 days with sacrifice 6 hr after the last administration. CP at a dose of 30 mg/kg and DN at 300 mg/kg were injected intraperitoneally; the dyes at doses of 0.5, 5 and 50 mg/kg were given orally. Under all the protocols applied, E160e at a dose of 50 mg/kg caused a significant reduction of both DN and CP effects. At 5 mg/kg this dye reduced the effects of the mutagens only under the pretreatment regimen. Pretreatment with E160a at doses of 5 and 50 mg/kg resulted in a meaningful reduction of the DN effect. Under the combined treatment with mutagens this dye reduced both CP and DN effects.

Antioxidant activity of Tinospora cordifolia and its usefulness in the amelioration of cyclophosphamide induced toxicity

Extract of Tinospora cordifolia has been shown to inhibit the lipid peroxidation and superoxide and hydroxyl radicals in vitro. Concentration needed for 50% inhibition was 6 mg and 12.5 mg/ml, respectively. The extract was also found to reduce the toxic side effects of cyclophosphamide administration (25 mg/kg b.wt, 10 days) in mice hematological system by the free radical formation as seen from total white blood cell count, bone marrow cellularity and alpha-esterase positive cells. Moreover, administration of the extract partially reduced the elevated lipid peroxides in serum and liver as well as alkaline phosphatase and glutamine pyruvate transaminase. This indicates the use of Tinospora extract in reducing the chemotoxicity induced by free radical forming chemicals.

Modulation of the potency of promutagens and direct acting mutagens in bacteria by inhibitors of the multidrug resistance mechanism

Multiple drug resistance (MDR) mechanisms are known to limit the effectiveness of some cancer chemotherapies, probably through enhancing P-glycoprotein-mediated drug efflux from mammalian cells. Similar mechanisms appear to act in other organisms, including bacteria, and may affect not only the toxicity but also the mutagenicity of certain chemicals. At least in some experimental situations, MDR can be overcome through concomitant treatment of the cells with various types of inhibitors. Two MDR inhibitors, verapamil, a calcium channel blocker, and trifluoperazine, a calmodulin inhibitor, were assayed for their ability to modulate the potency of nine mutagens with varying mechanisms of action in various Salmonella typhimurium his- strains. Neither verapamil nor trifluoperazine affected the direct mutagenicity of sodium dichromate and 2-methoxy-6-chloro-9[3-(2-chloroethyl)amino-propyl-amino] dihydrochloride (ICR 191) or the S9-mediated mutagenicity of benzo[a]pyrene and 2-amino-3,4-dimethyl-amidazo[4,5-f]quinoline (MeIQ). Both modulators enhanced the direct mutagenicity of doxorubicin. Moreover, trifluoperazine sharply increased the S9-mediated mutagenicity of cyclophosphamide and 2-aminofluorene, while it consistently decreased the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The contrasting effect towards the aromatic amine 2-aminofluorene and the heterocyclic amine Trp-P-2, representative of important chemical families responsible for the bacterial mutagenicity of cigarette smoke, may explain the observed lack of influence of trifluoperazine on the mutagenicity of a cigarette smoke condensate. These observations extend the known range of chemical types whose mutagenicity can be modulated by inhibitors of MDR and suggest that there may be value in adding MDR inhibitors, especially trifluoperazine, to optimize the detection of mutagenicity by certain types of chemicals in the Salmonella/mammalian microsome mutagenicity test.

Biphasic emetic response of cyclophosphamide in the ferret

Cyclophosphamide (177 mg/kg, IV: n = 8) produced a biphasic emetic response in the ferret with a mean +/- SE of 23.3 +/- 4.0 emetic episodes during a 4-h observation period. The emetic profile of cyclophosphamide showed a first phase with 18.6 +/- 3.9 episodes and a second phase with 4.7 +/- 1.2 episodes. Ondansetron (0.07 and 0.13 mg/kg, IV) and droperidol (0.25 and 0.79 mg/kg, IV) significantly reduced the number of emetic episodes in the first phase. Metoclopramide (2.24, 4.08, and 7.07 mg/kg, IV) also significantly reduced the number of emetic episodes in the first phase, and the dose of 7.07 mg/kg completely prevented emetic episodes in the second phase. In addition, ondansetron-treated ferrets (0.04, 0.07, and 0.13 mg/kg, IV) had a significant increase in the number of emetic episodes in the second phase.

The NK1 antagonist GR203040 inhibits cyclophosphamide-induced damage in the rat and ferret bladder

1. The effect of the tachykinin neurokinin1 (NK1) receptor antagonist GR203040 on cyclophosphamide (CYP)-induced bladder damage was investigated in rats and ferrets. The 5-hydroxytryptamine3 receptor antagonists ondansetron and granisetron were similarly examined in ferrets. 2. In the rat, GR203040 (10 and 30 mg/kg i.p.) reduced the CYP-induced plasma protein extravasation in the bladder by 44% and 73%, respectively (P < 0.05 and 0.005; cf. CYP controls); in the ferret, a 57% reduction (P < 0.005) was observed after GR203040 (0.3 mg/kg SC). No decrease was observed in ferrets with either ondansetron or granisetron (1 mg/kg SC). 3. GR203040 attenuated the CYP-induced damage in the rat and ferret bladder, at the same dose in the ferret previously shown to inhibit CYP-induced emesis.

Phenethyl isothiocyanate modulates clastogenicity of mitomycin C and cyclophosphamide in vivo

Phenethyl isothiocyanate (PEITC), a constituent of many cruciferous vegetables, is an effective chemopreventive agent against N-nitrosamine-induced carcinogenesis. We have investigated the extent to which PEITC modulates the clastogenicity of standard genotoxicants, mitomycin C and cyclophosphamide, using bone marrow cells of Swiss albino mice. PEITC, 1 mumol/kg body weight in corn oil was administered by gavage for 7 consecutive days to prime the animals. 24 h later, mice received a single dose of cyclophosphamide (10 or 20 mg/kg body weight) or mitomycin C (1 or 2 mg/kg body weight) intraperitoneally. Clastogenicity of the chemicals was compared using PEITC-primed and non-primed animals 24 h after clastogen treatment. As a single agent, PEITC is not clastogenic even after 7 days of priming. Oral priming with PEITC decreased the aberrations per cell values by 22-67% in all cases. PEITC could only alleviate the clastogenicity of 1 mg/kg body weight mitomycin C to near-control values (p < or = 0.05). Although PEITC is reported to be effective against N-nitrosamine-induced tumorigenesis by preventing metabolic activation and by blocking the reactive species formed, it is virtually ineffective against the clastogenicity of cyclophosphamide. The results of inhibition by PEITC of the clastogenicity of mitomycin C suggest that the modulation of mitomycin C bio-activation contributes to, but may not be sufficient for, PEITC chemoprevention of clastogenicity by mitomycin C.

Teratogen-induced apoptosis may be affected by immunopotentiation

Intra-uterine immunization of mice with paternal allogeneic or xenogeneic (rat) splenocytes was found to increase embryo tolerance to cyclophosphamide (CP)-induced teratogenesis. As the CP-induced teratogenic effect was shown to be associated with apoptosis, the present study was designed to investigate whether the protective effect of immunopotentiation may be realized via an alteration of CP-induced apoptosis. Various doses of CP were injected intraperitoneally into ICR mice on day 12 of pregnancy. Intra-uterine immunization with xenogeneic rat splenocytes was carried out 3 weeks before mating. Implantation sites, resorptions, live and dead fetuses, as well as soft tissue anomalies and external malformations, were recorded to evaluate the CP-induced embryotoxic effect. In parallel, flow cytometric analysis and DNA fragmentation assay were used for evaluation of CP-induced apoptosis in limbs, tail and whole embryos. The treatment of mothers with a high dose of CP induced the death of almost all embryos and striking fetal growth retardation in survivors. This strong embryotoxic effect was accompanied by very prominent DNA degradation in cells collected from whole embryos. Immunostimulation caused a dramatic decrease of embryonal loss (by approximately 50%) and a significant (about 30%) increase in fetal weight. Such an increase in fetal survival and in fetal weight was found to be accompanied by a clear decrease in apoptosis level in embryo cell population as judged by DNA gel electrophoresis with subsequent quantitation of DNA fragmentation in negatives by an image analysis technique. After treatment with a low dose of CP, a decrease in the proportion of fetuses with limb and tail anomalies in immunized females was accompanied by a decrease in the proportion of apoptotic nuclei in cells taken from limbs and tails. The results of this study suggest that the teratogen-induced apoptosis may, at least partly, be dependent on fetomaternal immune interactions.

Sensitization of human breast cancer cells to cyclophosphamide and ifosfamide by transfer of a liver cytochrome P450 gene

The cancer chemotherapeutic agent cyclophosphamide (CPA) and its isomer ifosfamide (IFA) are alkylating agent prodrugs that require metabolism by liver cytochrome P450 (P450) enzymes for antitumor activity. The therapeutic effectiveness of these oxazaphosphorines is limited by the hematopoietic, renal, and cardiac toxicity that accompanies the systemic distribution of liver-derived activated drug metabolites. Transfer of a liver cytochrome P450 gene, CYP2B1, into human breast MCF-7 cancer cells is presently shown to greatly sensitize these cells to oxazaphosphorine toxicity as a consequence of the acquired capacity for intratumoral CPA and IFA activation. Thus, CPA and IFA were highly cytotoxic to MCF-7 cells following stable transfection of CYP2B1 but exhibited no toxicity to parental tumor cells or to a beta-galactosidase-expressing MCF-7 transfectant. This cytotoxicity could be appreciably blocked by the CYP2B1 inhibitor metyrapone. Cell cycle analysis revealed that CPA arrested the CYP2B1-expressing cells, but not CYP2B1-negative cells, at G(2)-M phase. A strong bystander cytotoxicity effect that does not require direct cell-cell contact was mediated by CYP2B1-expressing MCF-7 cells on non-CYP2B1 cells. Intratumoral CYP2B1 expression conferred a distinct therapeutic advantage when treating MCF-7 tumors grown in nude mice with CPA, as revealed by a 15-20-fold greater in vivo cytotoxicity, determined by tumor excision/colony formation assay, and by the substantially enhanced antitumor activity, monitored by tumor growth delay, for CYP2B1-e xpressing MCF-7 tumors as compared to CYP2B1-negative control tumors. These enhanced therapeutic effects were obtained without any apparent increase in host toxicity. To evaluate the extent to which a CPA/P450 gene therapy strategy may be generally applicable to other tumor cell types, a replication-defective recombinant adenovirus carrying the CYP2B1 gene driven by the cytomegalovirus (CMV) promotor ad.CMV-2B1 was constructed and used to infect a panel of human tumor cell lines. Ad.CMV-2B1 infection rendered each of the cell lines highly sensitive to CPA and IFA cytotoxicity, with substantial chemosensitization seen at multiplicities of infection as low as 10. The CPA/P450 prodrug activation system may thus serve as a useful paradigm for further development of novel cancer gene therapy strategies that utilize drug susceptibility genes to significantly potentiate the antitumor activity of conventional cancer chemotherapeutic agents.

Alpha-tocopherol ameliorates cyclophosphamide-induced hyperlipidemia in fibrosarcoma-bearing rats

Cyclophosphamide, an alkylating agent, is currently being used for the treatment of various types of cancer, either alone or in combination with other cytostatic drugs. However, cyclophosphamide has a detrimental effect on lipid metabolism and causes hyperlipidemia in patients. Since alpha-tocopherol is known to reduce hyperlipidemia, we have investigated the effects of adding alpha-tocopherol to the cyclophosphamide treatment. Our study, carried out on fibrosarcoma-bearing rats, shows that alpha-tocopherol markedly reduces cyclophosphamide-induced hyperlipidemia and brings lipid metabolism down to values observed in untreated controls.

Inhibition by capsaicin against cyclophosphamide-induced clastogenicity and DNA damage in mice

We have demonstrated in an earlier paper that capsaicin, the pungent principle of red hot chili, has a potent anti-oxidant property that interferes with free-radical involved mechanisms. In the present paper we demonstrate that capsaicin significantly inhibits cyclophosphamide-induced (i.p.) chromosomal aberrations and DNA strand breakages. This protective action of capsaicin against CP-induced toxicity may possibly be linked with its already reported 'desensitisation' effect against chemical irritant-induced damages.