Cytoprotective and genotoxic effects of vitamins K1 and B1 on irinotecan in vitro

Cultured human lymphocytes were treated with vitamins K₁ and B₁, potential anticancer agents, either alone or in combination with irinotecan, a semisynthetic analogue of camptothecin. The frequency of sister chromatid exchanges (SCEs) was measured as an indicator of genotoxicity and the proliferation rate index (PRI) and mitotic index (MI) was measured as indicators of cytostatic effect. Vitamin K₁ alone did not induce SCEs at the concentrations tested and combined with irinotecan does not increase SCE rates induced by irinotecan alone. Vitamin B₁ significantly increased SCEs and, in combination with irinotecan, increased rates further (p < 0.05). Vitamin K₁ decreased PRI and MI in combination with irinotecan, there were further increases in MI. At a low concentration, vitamin B₁ reduced the levels of SCE and increased PRI induced by irinotecan. The use of these vitamins in combination with antitumor agents might reduce clinical side effects of the antineoplastics.

Sister chromatid exchange assay as a predictor of tumor chemoresponse

Sister Chromatid Exchanges (SCEs) are known to enhance as a consequence of exposure to various mutagenic agents and appear to indicate DNA damaging effects and/or subsequent repair by homologous recombination (HR). DNA damage plays an interesting role in the majority of mechanisms underlying the effects of antitumor drugs, since the genetic activity of the plethora of these agents is due to their ability to damage the DNA. The DNA-effects of antitumor agents towards normal cells (genotoxicity) are great drawbacks of antitumor therapy and are connected to important adverse health effects in cancer patients undergoing chemotherapy. On the other hand, failure of chemotherapy in many cases is due to the DNA repair ability which cancer, like normal cells, also possess. As both DNA repair and genotoxic exposure are expected to vary among patients, correlating SCEs frequencies with only individual repair capacity may be feasible to predict. Cancer risk has not been observed to be associated with high SCEs levels. Since the administration of effective antitumor drugs with limited adverse effects is of great importance in the success of anticancer therapy, a lot of interest has been directed toward the development of methods and approaches that would enable the correct selection of appropriate drugs prior to the initiation of therapy on an individual basis. To this effect, more than 30 years ago, an investigation of the ability of the in vitro and the in vivo SCEs-assay to predict the in vitro and in vivo sensitivity of tumor cells to newly synthesized drugs or to those already in use began. In this short review a critical appraisal of the SCEs-assay as an important biomarker used for predicting cancer chemo-response as well as a summary of the key findings from several studies published within the last 20 years in this field is performed.

Synthesis, characterization, toxicity, cytogenetic and in vivo antitumor studies of 1,1-dithiolate Cu(II) complexes with di-, tri-, tetra- amines and 1,3-thiazoles. Structure-activity correlation

A series of new mixed-ligand neutral copper(II) complexes of the general type [Cu(amine)(i-MNT)] and [Cu(tz)(i-MNT)] was prepared and characterized by elemental, spectroscopic methods, mu(eff), Lambda(mu) measurements and molecular modeling studies. The acute toxicity, the cytogenetic and the in vivo antitumor activity of the new complexes, is related to their chemical and physicochemical properties. Among the Cu(II) compounds tested the complex with 2-amino-5-methyl thiazole increases significantly the life span of leukemia P388 bearing mice in vivo.

Comparison of new nitrosoureas esters with modified steroidal nucleus for cytogenetic and antineoplastic activity

Nitrosourea is decomposed under physiological conditions to react with biological macromolecules by two mechanisms: alkylation (with proteins and nucleic acids) and carbamoylation (with proteins but not nucleic acids). It has been suggested that the alkylating action is responsible for the therapeutic effects of nitrosoureas, and that the carbamoylation activity leads to toxicity effects. In order to reduce systemic toxicity and improve specificity and distribution for cancer therapy, 2-haloethyl nitrosourea has been esterified with modified steroids, which are used as biological platforms for transporting the alkylating agent to the tumor site in a specific manner. The cytogenetic and antineoplastic effect were studied of seven newly synthesized esters of N,N-bis(2-chloroethyl)alanyl carboxyl derivatives with a modified steroidal nucleus (compounds 1-7). As a very sensitive indicator of genotoxicity the Sister Chromatid Exchange (SCE) assay was used and as a valuable marker of cytostatic activity the cell Proliferation Rate Index (PRI) in cultures of normal human lymphocytes was used. The order of magnitude of the cytogenetic activity on a molar basis (15, 30, 120 microM) of the compounds was 7>>6>3>5>2>4>1. The most active compound 7 has an enlarged (seven carbon atoms) A ring modified with a lactam group (-NHCO-) with the nitrosourea moiety esterified at position 17 In the group of seven substances a correlation was observed between the magnitude of SCE response and the depression in PRI (r=-O, 65, p<0.001). According to the criterion of activity of National Cancer Institute (NCI), the order of antineoplastic activity of compounds on lymphoid L1210 leukemia is 7>6>2>5>4>3>1 and on lympocytic P388 leukemia cells is 7>2>6>5>4>3>1. The present results are in agreement with previous suggestions that the effectiveness in cytogenetic activity may well be correlated with antitumor effects [T/C: 248% for the compound 7 in 250 mg/kg b.w.; T/C: mean survival time of drug-treated animals (T) (excluding long term survivals) vs. corn-oil-treated controls (C)].

Antileukemic and Cytogenetic Activity by Triple Administration of Three Modified Steroidal Derivatives of Nitrogen Mustards

Combination chemotherapy is widely and routinely used for most cancer patients. The main objective of this study is an effort to develop new anticancer drugs and procedures with enhanced antitumor activity and reduced toxicity. This study was designed to determine the antileukemic and cytogenetic activity of five mixtures of three specific steroidal esters of aromatic nitrogen mustards in different proportions. This is the next step of two previous studies where the combination of two such esteric analogues was investigated with promising results. All of the five mixtures used proved active against leukemia P388 and in the induction of sister chromatid exchanges, indicating that the combination of the same class of compounds can be successful, especially when a highly potent agent is combined with another less active but probably mechanistically supplementary one. These results can be used in future experiments in order to further scout the specific role of the steroidal part of these molecules in the antileukemic potency of them.

Synergistic antitumor activity of oxaliplatin in combination with gemcitabine in pancreatic tumor-bearing mice

Oxaliplatin (OX) and gemcitabine (GEM) are both drugs with proven clinical activity in various tumor types, have no overlapping toxic side effects and are different with respect to cellular metabolism. Therefore, we performed an in vivo study to determine the efficacy of the combination of these two drugs to optimize the scheduling of both substances using pancreatic ductal adenocarcinoma PAN-02, subcutaneously growing in C57Bl mice. A total of 164 mice were used for cytotoxicity and antitumor studies. The combination therapy resulted in better results than those observed when the drugs were administered individually. GEM (58 mg/kg) and OX (1.0 mg/kg) achieved a 52% reduction in tumor size on day 28 after transplantation and a T/C value of 168% when the intermittent treatment schedule on days 1, 4 and 7 after inoculation was used. This treatment schedule was superior to other therapeutic schedules, producing a synergistic antitumor effect much higher than the one expected by the simple addition of the effects by OX and GEM acting independently.

Rational Design, Synthesis and In Vitro Evaluation of Three New Alkylating Steroidal Esters

Recent studies have indicated that minor functional changes on the steroidal part of complex molecules, comprising of an alkylating moiety and a steroidal congener, lead to compounds with enhanced biological activity. The observed induction of the genotoxic, cytotoxic and antileukemic effects suggest a determinative role of the steroidal congener on the mechanism of action. In order to further elucidate the structural requirements responsible for this, we designed and synthesized a new modified steroid, carrying a 17beta-acetamide substituent and a B lactamic ring, and studied the ability of its esters with three potent nitrogen mustards to induce sister chromatid exchange (SCEs) and to inhibit cell proliferation in normal human lymphocytes in vitro. The role of the steroidal skeleton was clearly stated by the results of the in vitro evaluation of the final compounds, as all three derivatives proved better inducers of SCE (58-102 SCE/cell) and cell division delays (1.18-1.25 PRI) than the simple nitrogen mustards (24-38 SCE/cell and 1.51-1.62 PRI). Obviously, the steroidal module enhances the formation of DNA adducts that cannot be repaired by excision repair enzymes probably through the induction of the interaction of these complex compounds with different base sequences or by disabling the repair mechanisms through the blockage of the enzymes responsible for excision repair. On the other hand, it seems that these compounds also act through a parallel site of action responsible for cell death when their primary binding site becomes saturated, as in higher concentrations two of the derivatives tested showed enhanced cytotoxicity while their ability to induce SCE stabilized.

Comparative study of sister chromatid exchange induction and antitumor effects by homo-aza-steroidal esters of [p-[bis(2-chloroethyl)amino]phenyl]butyric acid

The present work was undertaken in order to test the hypothesis that the Sister Chromatid Exchange (SCE) assay in vitro can be used for the prediction of in vivo tumor response to newly synthesized potential chemotherapeutics. The effect of three homo-aza-steroidal esters containing the -CONH- in the steroidal nucleus, 1, 2, and 3 on SCE rates and on cell kinetics in cultured human lymphocytes was studied. The antitumor activity of these compounds was tested on leukemia P388- and leukemia L1210-bearing mice. The three substances induced statistically significant enhancement of SCEs and of cell division delays. Compounds 1 and 3 were identified, on a molar basis, as more effective inducers of SCEs and of cell division delays compared with compound 2. Compounds 1 and 3 had upon both experimental tumors better therapeutic effects compared with compound 2 at equitoxic doses. Therefore, the order of the antitumor effectiveness of the three compounds coincided with the order of the cytogenetic effects they induced.

Synthesis and cytogenetic effects of aminoquinone derivatives with a di- and a tripeptide

Quinones are of significant interest due to their important role in specific cellular functions. Quinoproteins are a big class of oxyreductive agents occurring in bacteria and other organisms. In this investigation derivatives of 2-amino-1,4-benzoquinone, 2-amino-1,4-naphthoquinone and 2-amino-5,8-dihydroxy-1,4-naphthoquinone with a di- and a tripeptide were prepared for first time. The effect of the synthesized compounds on sister chomatid exchange (SCE) rates and human lymphocyte proliferation kinetics on a molar basis was studied. Among these coupled products the most effective in inducing SCEs and depressing proliferation rate indices is the coupling product of 2-amino-1,4-naphthoquinone with the tripeptide GHK (10). Next in order of magnitude in inducing cytogenetic effects is 2-amino-1,4-naphthoquinone (2) and its coupling products with glycine and serine (4 and 5), while the rest displayed marginal activity.

A comparative study on cytogenetic and antineoplastic effects induced by two modified steroidal alkylating agents

We investigated the effects of two newly synthesized steroidal derivatives of nitrogen mustard on sister chromatid exchange rates and on human lymphocyte proliferation kinetics. The compound 33-hydroxy-5alpha,22alpha-spirostan- 12-one-p-(N,N-bis(2-chloroethyl)amino)phenylacetate(1) was, on a molar basis, less effective in inducing sister chromatid exchange and suppressing cell proliferation rate indices than compound 3beta-hydroxy-12alpha-aza-C-homo-5alpha,22alpha-spirostan-12-one-p-(N,N-bis(2-chloroethyl)amino)phenylacetate(2). A correlation was observed between the magnitude of the sister chromatid exchange response and the depression of cell proliferation index. We also studied the effects of the aforementioned compounds on Lewis lung carcinoma. The order of the percent inhibition of tumor growth achieved by the compounds coincides with the order of the cytogenetic effects they induce.

Platinum(II) and palladium(II) complexes with 2-acetylpyridine thiosemicarbazone: cytogenetic and antineoplastic effects

The effect of three novel complexes of Pt(II) and three complexes of Pd(II) with 2-acetylpyridine thiosemicarbazone (HAcTsc) on sister chromatid exchange (SCE) rates and human lymphocyte proliferation kinetics on a molar basis was studied. Also, the effect of Pt(II) and Pd(II) complexes against leukemia P388 was investigated. Among these compounds, the most effective in inducing antitumor and cytogenetic effects were the complexes [Pt(AcTsc)2] x H2O and [Pd(AcTsc)2] while the rest, i.e. (HAcTsc), [Pt(AcTsc)Cl], [Pt(HAcTsc)2]Cl2 x 2H2O, [Pd(AcTsc)Cl] and [Pd(HAcTsc)2]Cl2, displayed marginal cytogenetic and antitumor effects.

Enhanced cytogenetic and antitumor effects by 9-nitrocamptothecin and antineoplastics

Enhanced sister chromatid exchange (SCE) frequency by either melphalan (Mel) or epirubicin (Epir) was observed when human lymphocytes were exposed in vitro to 9-nitro-20(S)-camptothecin (9NC). A correlation was observed between the magnitude of the SCE response and the depression of the cell proliferation index. The antitumor activity of Mel and of 9NC was tested on leukemia P-388-bearing mice. The two chemicals in combination enhance antitumor activity in a synergistic manner. Therefore, the in vivo antitumor effect of Mel in conjunction with 9NC appears to correlate well with the in vitro synergistic effect on SCE induction caused by the combined Mel plus 9NC treatment. Teratogenesis Carcinog. Mutagen. 20:141-146, 2000.

Synergistic antineoplastic and cytogenetic effects by the combined action of two homo-aza-steroidal esters of nitrogen mustards on P388 and L1210 leukaemias in vivo and in vitro

In order to increase the damaging effects on specific DNA sequences and decrease the subsequent toxicity, the use of homo-aza-steroidal esters of nitrogen mustards is already known. Two specific homo-aza-steroidal esters were mixed at different proportions and the resultant final mixtures were tested in vivo and in vitro. The effects of these on P388 and L1210 leukaemias, on SCE rates and on human lymphocyte proliferation kinetics were studied. The results demonstrate that the combined substances enhanced SCE induction (p < 0.05) and antitumour activity (p < 0.02) in a synergistic manner. A correlation was observed (p < 0.001) between the magnitude of the SCE response and the depression of the cell proliferation index.

Lack of genotoxicity of silver iodide in the SCE assay in vitro, in vivo, and in the Ames/microsome test

Silver iodide was evaluated for mutagenicity in the Ames/microsome test (strains TA 1535, TA 102, TA 97, and TA 98) and for the ability to induce Sister Chromatid Exchanges (SCE) in human cultured lymphocytes and in P388 lymphocytic leukemia cells cultured in the mouse peritoneal cavity. From the cytogenetic in vitro studies, it was observed that silver iodide, either in acetone solutions or as a suspension with polyacrilamide, scarcely causes a doubling effect on SCEs at nearly toxic concentrations (1 microg/ml). Such a doubling effect by silver iodide on SCEs in P388 leukemia cells in vivo was not achieved even after using 100 microg/g mouse body weight. In the Ames/microsome test actually a doubling effect on revertants was only isolately achieved with 30 microg/ml in TA 102 (S9-) and at 150 microg/ml in TA 97 (S9+) doses, which appear to be nearly toxic for bacteria.

Enhanced cytogenetic and antineoplastic effects by the combined action of two esteric steroidal derivatives of nitrogen mustards

The authors studied the effect of two modified steroids containing different proportions (%) of alkylating agents alone or in combination on sister chromatid exchange (SCE) rates and on human lymphocyte proliferation kinetics. The antitumor activity of these compounds was tested on leukemia P388- and leukemia L1210-bearing mice. The two chemicals in mixtures enhance SCE induction and antitumor activity in a synergistic manner. The homo-aza-steroidal ester of p-bis(2-chloroethyl)aminophenyl acetic acid was found to be more effective than the homo-aza-steroidal ester of o-bis(2-chloroethyl)aminobenzoic acid in causing cytogenetic damage and antineoplastic activity. A correlation was observed between the magnitude of the SCE response and the depression of the cell proliferation index. The order of the antitumor effectiveness of the five different treatments tested coincided with the order of the cytogenetic effects they induced.

Antineoplastic and cytogenetic effects of platinum(II) and palladium(II) complexes with pyridine-2-carboxyaldehyde-thiosemicarbazone

The effect of six novel complexes of Pt(II) and Pd(II) with pyridine-2-carboxyaldehyde thiosemicarbazone (HPyTsc) on sister chromatid exchange rate and human lymphocyte proliferation kinetic was studied. Also, the effect of Pt(II) and Pd(II) complexes against leukemia P388 was investigated. Among these compounds, the most effective in inducing cytogenetic and antineoplastic effects are the complexes [Pd(PyTsc)2] and [Pt(PyTsc)2]. Next in order of magnitude in inducing antineoplastic and cytogenetic effects is the compound [Pt(HPyTsc)2]Cl2 while the rest, i.e. [Pd(PyTsc)Cl], HPyTsc, [Pd(HPyTsc)2]Cl2, and [Pt(PyTsc)Cl], show marginal cytogenetic and antineoplastic effects.

A comparative study of the cytogenetic and antineoplasmatic effects induced by carboplatin in combination with niacin in human lymphocytes in vitro and in Ehrlich ascites tumor cells in vivo

Enhanced sister chromatid exchange (SCE) levels and cell division delays were observed when cultured human lymphocytes treated with carboplatin (cPt) were exposed to niacin. Cytogenetic damage was also observed by cPt when Ehrlich ascites tumor (EAT) cells were exposed in vivo to nontoxic concentrations of niacin. One hour before intraperitoneal injection of 5-bromodeoxyuridine, adsorbed to activated charcoal, EAT-bearing mice treated intraperitoneally with cPt appeared to have a dose-dependent increase in SCEs and cell division delays. Niacin increased the survival time of the EAT-bearing mice treated with cPt and markedly reduced the ascitic volume. Therefore the in vivo antitumor effect of cPt in conjunction with niacin appears to correlate well with the in vitro or in vivo synergistic effects on cytogenetic damage caused by the combined cPt plus Niacin treatment upon human lymphocytes or EAT cells, respectively.

Antitumor and cytogenetic effects of esteric (ASE) and amidic (ASA) steroidal derivative of p-bis (2-chloroethyl) amino phenylacetic acid (CAPA). A comparative study

The homo-aza-steroidal ester of p-bis (2-chloroethyl) amino phenylacetic acid (ASE) (I) the homo-aza-steroidal amide of p-bis (2-chloroethyl) amino phenylacetic acid (ASA) (II), and the parent compound p-bis (2-chloroethyl) amino phenylacetic acid (III) were tested in an effort to evaluate their ability to inhibit a transplanted leukemia (P388) in vivo, and the DNA synthesis of P388 cell cultures in vitro. The compounds' effects on Sister Chromatid Exchange (SCE) rate and on human cell proliferation kinetics in vitro were also studied. The above mentioned compounds were identified as displaying cytogenetic, cytostatic and antineoplastic effects, the ester compound being the more potent. The main conclusion from this study is that the existence of the esteric bond is necessary for the expression of the antitumor activity. The synthetic route for the preparation of the amidic derivative (II), as new product, is also reported.

Antineoplastic and cytogenetic effects of complexes of Pd (II) with 4N-substituted derivatives of 2-acetyl-pyridine-thiosemicarbazone

The effect of novel Pd(II) complexes with derivatives of 2-acetyl-pyridinethisemicarbazone, N4-ethyl (HAc4Et) and 3-hexamethyleneiminylthiosemicarbazone (HAchexim), on Sister Chromatid Exchange (SCE) rates and human lymphocyte proliferation kinetics was studied. Also, the effect of Pd(II) complexes on DNA synthesis of P388 and L1210 cell cultures and against Leukemia P388 was investigated. Among these compounds, the compound Bis(3-hexamethyleneiminyl-2-acetylpyridine-thisemicarbazonato++ +) palladium (II) was found to be distinctly effective against Leukemia P388, in inhibiting incorporation of 3H-thymidine into DNA and in inducing SCEs and cell division delays.

Comparative study on Salmonella mutagenicity and on cytogenetic and antineoplastic effects induced by cyclophosphamide and 3-aminobenzamide in cells of three transplantable tumours in vivo

Synergistically enhanced sister chromatid exchange (SCE) frequency by cyclophosphamide (CP) was observed when L1210 lymphoid tumor cells were exposed in vivo to a non-toxic concentration of 3-aminobenzamide (3-AB). Additive effects in SCE induction in vivo were observed when either Ehrlich ascites tumor (EAT) cells or P388 lymphocytic leukemia cells treated with CP were exposed to 3-AB in vivo. 3-AB enhanced the survival time of L1210 tumor bearing BDF1 mice treated with CP. However, the combined CP plus 3-AB treatment did not increase the survival of either EAT BALB/c- or P388 BDF1-tumor bearing mice compared with the effect on survival by CP alone. Therefore the in vivo differential antitumor effect, by CP in conjunction with 3-AB, appears to correlate well with the in vivo differential effect on cytogenetic damage caused by the combined CP plus 3-AB treatment. In the Salmonella typhimurium/mammalian microsome test CP appears to have a dose dependent ability to induce base-pair substitutions in strains TA 100 and TA 1535 and frameshift mutations in strains TA 98 and TA 1537. Both types of mutation were synergistically increased in the presence of 3-AB.

Comparative study of SCE induction and cytostatic effects by homo-azasteroidal esters of N,N-bis(2-chloroethyl)aminobenzoic acid in human lymphocytes

The effect of homo-azasteroidal esters of benzoic acid mustard isomers and the 4-methyl derivatives, which have steroidal lactams as a biological basis, on cytogenetic damage was studied. Twenty compounds were comparatively studied, on a molar basis, as regards their ability to induce sister-chromatid exchanges (SCEs) and cell division delays. A correlation between potency for SCE induction, effectiveness in cell division delay and previously established antitumor activity of these compounds was observed.

Comparative study on cytogenetic damage induced by homo-aza-steroidal esters in human lymphocytes

The effect of P[N,N-bis(2-chloroethyl)amino]phenylacetate esters of 3 beta-hydroxy-N-methyl-17 alpha-aza-D-homo-5 alpha-androstan-17-one (compound 3) and 3 beta-hydroxy-17 alpha-aza-D-homo-5 alpha-androstane (compound 2) on sister-chromatid exchange (SCE) frequencies and on human lymphocytes proliferation kinetics was studied. The results are compared with those of the P[N,N-bis(2-chloroethyl)amino]phenylacetate esters of 3 beta-hydroxy-17 alpha-aza-D-homo-5 alpha-androstan-17-one (compound 1). All compounds were found to be active in inducing markedly increased SCE rates and cell division delays. A correlation between potency for SCE induction, effectiveness in cell division delay and previously established antitumour activity of these compounds was observed.

Enhancement of cytogenetic damage and of antineoplastic effect in lymphoid L1210 leukemia cells treated with prostaglandin E2 and cyclophosphamide in vivo

An enhanced frequency of sister-chromatid exchanges (SCEs) and increased cell division delays induced by cyclophosphamide (CP) were observed when lymphoid L1210 leukemia cells were post-treated in vivo with prostaglandin E2 (PGE2). CP gave a slight, non-significant increase in survival while PGE2 gave a slight, non-significant decrease in survival. However, PGE2 in combination with CP was found to have a non-significant potentiating effect on survival in comparison with mice treated with CP alone. In mice treated with the combined CP (5 micrograms/g b.w.) plus PGE2 (2 micrograms/g b.w.) treatment, a significant (P < 0.01) enhancement of survival time in comparison with the untreated controls was observed.

Comparison of current alkylating agents with a homo-aza-steroidal ester for antineoplastic activity

The modified steroidal alkylating agent, 17 beta-hydroxy-3-aza-A-homo-4 alpha-androsten-4-one-p-bis(2-chloroethyl)aminophenoxyacetate++ + has been tested against L1210 and P388 leukemias, and Lewis lung cancer, on DNA synthesis of EAT, L1210, P388, and BHK cell cultures, and on the induction of sister chromatid exchange. Comparable studies in vivo and in vitro were also done with p-bis(2-chloroethyl)aminophenoxyacetic acid, cyclophosphamide, melphalan, and chlorambucil.

Enhancement of antineoplastic effect and attenuation of sister chromatid exchanges by prostaglandin E2 in Ehrlich ascites tumour cells treated with cyclophosphamide in vivo

Reduced sister chromatid exchanges (SCE) frequency in response to cyclophosphamide (CP) was observed when Ehrlich ascites tumour (EAT) cells were exposed in vivo to 2 micrograms/g body weight of prostaglandin E2 (PGE2). 1 h before i.p. injection of 5-bromodeoxyuridine (BrdUrd) adsorbed to activated charcoal, EAT-bearing mice treated i.p. with CP appeared to have increased SCE rates and cell division delays. PGE2 had no effect on survival and in inhibiting tumour growth. CP had only a slight non-significant effect on survival and in inhibiting tumour growth. In mice treated with the combined CP (5 micrograms/g bd wt) plus PGE2 (2 micrograms/g bd wt) a significant enhancement (P < 0.01) of survival time was accompanied by inhibition of tumour growth (P < 0.01) in comparison with the untreated controls. These data imply that SCEs might result from errors in a repair process which might involve a PGE2 sensitive step.

Cytogenetic damage by melphalan and hyperthermia in patients with an initial epileptic attack

Sister-chromatid exchanges (SCEs) and cell kinetics in cultured lymphocytes of patients with an initial epileptic attack, and prior to any anticonvulsant treatment, were studied. Spontaneous melphalan (MEL) and MEL-hyperthermia (MEL-HYP) induced SCE frequencies have been studied in 18 adults with an initial epileptic seizure. Fifteen age and sex matched healthy subjects were used as the control group. The incidence of spontaneous SCEs in lymphocytes from epileptics was not significantly greater than in those from the control subjects. However, when exposed to MEL in vitro, cells from both groups showed an increase in SCE frequency. When exposed to MEL and HYP (41 degrees C for 3 h) in vitro, cells from both groups showed a further increase in SCE frequency with yields from epileptics higher (P less than 0.05) than from controls. HYP in combination with MEL enhanced synergistically SCEs and cell division delays in both groups with synergistic effects in cells from epileptics (P less than 0.01 and P less than 0.01 respectively) higher than from controls (P less than 0.05 and P less than 0.05 respectively.

Frequencies of chromosomal aberrations in pesticide sprayers working in plastic green houses

The frequency of chromosome aberrations was studied in peripheral blood lymphocytes of 29 workers occupationally exposed to a mixture of pesticides and in 14 age- and sex-matched healthy controls. There was a significant increase in chromosome aberrations in sprayers when compared to unexposed persons (2.39% compared to 0.54%). No positive correlation between the frequency of chromosome aberrations and the duration of exposure was observed. No significant difference between smokers and non-smokers was found.

Chlorpromazine-induced damage on nucleic acids: a combined cytogenetic and biochemical study

Chlorpromazine is now emerging as an adjuvant chemotherapeutic agent for the treatment of neoplasia. This was further supported in the present study by the following lines of evidence: it was shown that chlorpromazine causes damage in a series of native nucleic acids, though at somewhat high concentrations. Furthermore, chlorpromazine and caffeine were shown to act synergistically to potentiate the cytogenetic effect of adriamycin on human lymphocytes in vitro and on Ehrlich ascites tumour (EAT) cells in vivo. It is suggested that chlorpromazine alone or in combination with caffeine may exert its cytotoxic effect on normal and neoplastic cells not only indirectly, i.e. by facilitating the intracellular retention of adriamycin, but also directly by intercalating into nucleic acids.

Enhanced genotoxicity by melphalan and hyperthermia in chronic heroin addicts

Spontaneous melphalan- (MEL-) and MEL-hyperthermia- (MEL-HYP-) induced sister chromatid exchange (SCE) frequencies have been studied in 12 chronic heroin addicts (HER AD) and in 12 age- and sex-matched healthy controls. The incidence of spontaneous SCEs in lymphocytes from the HER AD was significantly greater (P less than 0.001) than those from the control subjects. When exposed to MEL in vitro, cells from both groups showed an increase in SCE frequency with yields from HER AD higher than those from controls. When exposed to MEL and hyperthermia (41.5 degrees C for 3 h) in vitro, cells from both groups showed further increases in SCE frequency with yields from HER AD higher than those from controls. We observed that hyperthermia (HYP) in combination with MEL synergistically enhances SCEs and cell division delays in both groups, with the synergistic effects in cells from HER AD higher than those from controls.

Cytogenetic study for possible mutagenic activity induced by ice-nucleation bacteria or their metabolic products in human lymphocytes in vitro

A means for eliminating ice-nucleation-active (INA) bacteria, the microorganisms responsible for frost damage to plants at mild freezing temperatures, is the use as competitors of other naturally occurring, non-nucleating strains. Inactive mutants (INA-) of INA bacteria have been produced by genetic or chemical methods and proposed for biological control of INA populations. Since, however, the application of these INA- mutants in the field may create health hazards to animals, we have studied the possible mutagenic activity of the INA- mutants by examining chromosome aberrations, sister-chromatid exchange (SCE) frequencies, and proliferation kinetics of human lymphocyte cultures. These cultures were treated with: (a) a naturally occurring INA- bacterium (p 767), (b) 2 parental strains (cit 7 and cit 13) of INA bacteria isolated from Citrus orchards, and (c) 2 INA- mutant strains (cit 7 del 1b and cit 13-12), produced, respectively, by chemical modification and by deletion of the corresponding parental strains. Neither whole bacteria nor infiltrates of bacterial growth media, in which toxic metabolic bacterial products might have been released, induced elevation of either chromosome aberrations and SCEs or a cell-division delay. Negative results were also obtained when sonicated bacteria were tested for possible intracellular mutagenic components.

Synergistic induction of cytogenetic damage by the homo-aza-steroidal ester of p-bis(2-chloroethyl)aminophenylacetic acid in combination with caffeine in human lymphocytes in vitro and in Ehrlich ascites tumour cells in vivo

We studied the effects of caffeine alone or in combination with homo-aza-steroidal ester of p-bis(2-chloroethyl)aminophenylacetic acid (ASE, NSC 290205) on the frequency of SCEs and lymphocyte proliferation kinetics. Caffeine was found to act synergistically with ASE on the induction of SCEs when the two components were administered in combination. Caffeine was also found to act synergistically with ASE in inducing cell-division delays. Enhanced cytogenetic damage by ASE was observed when Ehrlich ascites tumour cells (EAT cells) were exposed in vivo to caffeine. ASE alone or in combination with caffeine caused a dose-dependent increase in SCE rates and cell-division delays. SCEs were demonstrated in EAT-bearing mice, by the i.p. injection of BrdUrd adsorbed onto activated charcoal, 1 h after the i.p. injection of ASE and/or caffeine.

Effects of alkylating antineoplastics alone or in combination with 3-aminobenzamide on genotoxicity, antitumor activity, and NAD levels in human lymphocytes in vitro and on Ehrlich ascites tumor cells in vivo

Enhanced cytogenetic damage by the homo-aza-steroidal ester of p-bis(2-chloroethyl)-aminophenylacetic acid (ASE) was observed when human lymphocytes in vitro or Ehrlich ascites tumor (EAT) cells in vivo were exposed to nontoxic concentrations of 3-amino-benzamide (3-AB). 3-AB at these concentrations was found to enhance synergistically the cytogenetic damage induced in vivo by cyclophosphamide (CP), a metabolically activated chemotherapeutic, or chlorambucil (CBC) in EAT cells. One hour before i.p. injection of 5-bromodeoxyuridine (BrdUrd) adsorbed to activated charcoal, EAT-bearing mice treated i.p. with ASE or CP showed a dose-dependent increase in sister chromatid exchange (SCE) rates and cell division delays. The treatment of human lymphocytes in vitro with ASE led to the depletion of cellular NAD, and addition of 3-AB, a potent inhibitor of poly(ADP-ribose)polymerase [P(ADPR)polymerase], to ASE-treated human lymphocytes prevented the drop of NAD, which remained at approximately control levels. Also, the in vivo treatment of EAT cells with CBC, ASE, or CP led to the depletion of NAD, whereas addition of 3-AB to CBC-, ASE- or CP-treated cells prevented the drop of NAD, which remained at nearly control levels. 3-AB in conjunction with CBC, ASE, or CP increased the survival time of the EAT-bearing mice and markedly reduced the ascitic volume. Thus cytogenetic damage induced by ASE plus 3-AB in vitro and by CBC, ASE, or CP plus 3-AB in vivo correlates well with 1) the prevention of NAD depletion in the presence of 3-AB in cells treated with the same alkylating agents in vitro or in vivo and 2) the in vivo antitumor effect by ASE, CBC, or CP in combination with 3-AB.

Comparative study on cytogenetic effects by diplatinum complexes of the ligands of naphthazarine and squaric acid in human lymphocytes

The effect of diplatinum complexes of the binucleating ligands of naphthazarine and squaric acid on Sister Chromatid Exchange (SCE) rates and human lymphocyte proliferation kinetics was studied. Squarodicisplatinum complex I, naphthazarindicisplatinum and squarodicisplatinum complex II induce cytotoxic effects as can be deduced from the resulted induction of SCEs and the produced cell division delays. Squarodicisplatinum complex I was found to be on a molar basis the most effective in causing markedly increased SCE rates and cell division delays. Cis-diaminodichloride platinum was found to be next in order of effectiveness with naphthazarindicisplatinum and squarodicisplatinum complex II following. Naphthazarine and SQA were found to be ineffective on induction of SCEs.

Enhancement of cytogenetic damage by chlorpromazine in human lymphocytes treated with alkylating antineoplastics and caffeine

In cultured human lymphocytes chlorpromazine (CPZ) was found to induce cell division delays and to have no effect on sister-chromatid exchanges (SCEs) or on mitotic indices (MIs). CPZ induces cytotoxic effects in combination with caffeine (CAF) and alkylating agents. In combination with CAF it induced cell division delays and suppression of MIs. In combination with melphalan (MEL) and CAF, CPZ synergistically induced SCEs, caused cell division delay and suppressed MIs. In combination with chlorambucil (CBC) and CAF, CPZ produced synergism on induction of SCEs, enhanced cell division delays and reduced MIs.

Enhancement of cytogenetic damage and of antineoplastic effect by caffeine in Ehrlich ascites tumor cells treated with cyclophosphamide in vivo

Enhanced cytogenetic damage by cyclophosphamide (CP) was observed when Ehrlich ascites tumor cells were exposed in vivo to nontoxic concentrations of caffeine. One h before i.p. injection of 5-bromodeoxyuridine adsorbed to activated charcoal Ehrlich ascites tumor-bearing mice treated i.p. with CP appear to have a dose-dependent increase in sister chromatid exchange rates and cell division delays. Caffeine increased the survival time of the Ehrlich ascites tumor-bearing mice treated with CP and markedly reduced the ascitic volume. Therefore, the in vivo antitumor effect by CP in conjunction with caffeine appears to correlate well with the in vivo synergistic effect on cytogenetic damage caused by the combined CP plus caffeine treatment.

Induction of cytogenetic damage by modified steroidal derivatives of p-bis(2-chloroethyl)aminophenylacetic acid in human lymphocytes

The effect of modified steroids, containing alkylating agents, on SCE rates and on cell kinetics in cultured human lymphocytes was studied. The homo-aza-steroidal ester of p-bis(2-chloroethyl)aminophenylacetic acid (ASE) was found to be the most effective in causing markedly increased SCE rates and cell division delays. The androsterone ester of p-bis(2-chloroethyl)aminophenylacetic acid (AE-CAPA) was found to be next in order of effectiveness with the lactone ester (LE-CAPA), chlorambucil ester 3 beta-hydroxy-13a-amino-13,17-seco-5a-androstan-17-oic-13,17-lactam (CBC-HAAL) and chlorambucil (CBC) following. p-Bis(2-chloroethyl)aminophenylacetic acid (CAPA) had only a small effect and 3 beta-hydroxy-13a-amino-13,17-seco-5a-androstan-17-oic-13,17-lactam (HAAL) had no effect at all. A correlation between potency for SCE induction, effectiveness in cell division delay and previously established antitumor activity of these drugs was observed.

Enhancement and attenuation of cytogenetic damage by vitamin C in cultured human lymphocytes exposed to thiotepa or L-ethionine

Vitamin C (vit C) at 2 mM enhanced sister chromatid exchange (SCE) frequencies induced by Thiotepa (THIO) or L-ethionine (L-ETH) in cultured human lymphocytes. However, when vit C was tested at 0.02 mM and 0.2 mM a rather protective effect on SCE rates induced by THIO or L-ETH was identified. Vit C (2 mM) caused a cell division delay in cultures treated with THIO or L-ETH. Division delays caused by THIO or L-ETH were reversed in the presence of 0.02 mM or 0.2 mM vit C. Mitotic indices (MIs) in cultures treated with THIO or L-ETH continued to be suppressed in the presence of 2 mM vit C. However, vit C at 0.02 mM reversed suppression of MIs caused by L-ETH or THIO. These findings illustrate the complexity of the interactions of vit C in biological systems and indicate that with different concentrations vit C can cause or prevent genetic toxicity.

Induction of sister-chromatid exchanges in heroin-cannabis, heroin and cannabis addicts

The aim of this study was to determine the frequency of sister-chromatid exchanges (SCEs) in heroin-cannabis, heroin and cannabis addicts. The group of 84 subjects consisted of 42 controls, 16 heroin-cannabis addicts, 12 heroin addicts and 14 cannabis addicts. The mean number of SCEs/cell was 12.95 in heroin-cannabis addicts, 12.05 in heroin addicts and 11.99 in cannabis addicts. These values are significantly (P less than 0.002) higher than the mean values found in controls. This increase in SCEs may be related to reduced DNA repair in chronic drug addicts, which would allow the fixation or retention of a greater fraction of the DNA lesions caused by normal environmental exposure.

Enhancement of cytogenetic damage by inhibitors of poly(ADP-ribose)polymerase in human lymphocytes exposed to antineoplastics in vivo and in vitro

The effect of benzamide (B) and 3-aminobenzamide (3-AB) on sister chromatid exchanges (SCEs) and cell kinetics induced in vitro by melphalan (MELPH) or thiotepa (THIO) was studied in normal human lymphocytes. The combined treatments with either MELPH or THIO plus B or 3-AB showed the potentiating ability on SCE rates and the ability to induce cell division delays of the latter chemicals. In a combined in vivo and in vitro study, lymphocytes taken from six cancer patients who had been given cytoxan by injection 2 hr before and then treated with theophylline (THEOPH) or B or 3-AB in vitro were found to have synergistically increased exchange rates and cell division delays. The frequency of SCEs in the patients own lymphocytes with and without exposure to inhibitor of Poly(ADP-ribose) polymerase (P(ADPR)polymerase) was determined before the cytostatic therapy and was used as a control for later comparison in each individual case. These results further substantiate the use of this approach for detecting the induction of cytogenetic damage concerning controlled mutagen human exposure in combined in vivo and in vitro studies. Chemically induced cytotoxicity manifested as an alteration (division delay) in cell kinetics and as synergistic DNA damage by cytostatics and inhibitors of P(ADPR)polymerase may be of use in the treatment of human cancer.

Induction of sister-chromatid exchanges and cell-cycle delays in human lymphocytes by vitamin A alone or in combination with melphalan and caffeine

In cultured human lymphocytes vitamin A was found to increase SCE rates, to reduce the mitotic index and to have no effect on cell kinetics. Vitamin A induces cytotoxic effects: in combination with melphalan (MELPH), as can be deduced from the resulted synergism on induction of SCEs, the produced cell division delay and the suppressed mitotic index; in combination with caffeine (CAF), producing synergism on induction of SCEs and suppressing the mitotic index; and in combination with MELPH and CAF, producing cell-cycle delays and reducing the mitotic index.

Synergistic induction of sister-chromatid exchanges in lymphocytes from normal subjects and from patients under cytostatic therapy by inhibitors of poly(ADP-ribose)polymerase and antitumour agents

The effects of nicotinamide on SCE rates induced in vitro by chlorambucil (CBC or melphalan (MELPH) or mitomycin C (MMC) was studied. The combined treatments with either CBC or MELPH or MMC and nicotinamide showed the potentiating ability of the latter drug. Theophylline and MELPH were also found to act synergistically on the induction of SCEs. In a combined in vivo and in vitro study, lymphocytes taken from 7 cancer patients who had been given cytoxan by injection 3 h before, were treated with nicotinamide or diphylline (DP) in vitro, and found to have synergistically increased exchange rates. This has implications for interpreting the repair processes involved, for monitoring drug combinations that synergistically damage DNA in vivo and in vitro and for identifying interindividual variation in the response to the treatment.

Practical applications of the SCE studies for guiding and improving chemotherapy

The effect of diphylline (DP) or (1,2-dihydroxy-3-propyl)-theophylline and theobromine (TB) on sister chromatid exchange (SCE) rates induced in vitro by cytosine arabinoside (AraC) was studied in normal human lymphocytes. The combined treatments with AraC plus DP or TB showed the potentiating ability of the latter drugs. In a combined in vivo and in vitro study, lymphocytes taken from 14 patients suffering from various types of cancer who had been given Cytoxan (5 patients) or AraC (9 patients) by injection 3 hr before and then treated with DP or TB in vitro were found to have synergistically increased exchange rates. This has implications for interpreting the repair processes involved and for monitoring drug combinations that synergistically damage DNA in vivo and in vitro.

Induction of sister-chromatid exchange in human lymphocytes by vitamin B6

Vitamin B6, or pyridoxine hydrochloride, enhanced sister-chromatid exchange (SCE) rates in cultured normal human lymphocytes. No increase was found in SCE frequency when lymphocytes were treated with pyridoxal-5-phosphate (P-5-P) or 4-pyridoxic acid (4-PA) to which vitamin B6 is finally converted.