Genotoxic and cytotoxic effects in the bone marrow of rats exposed to a low dose of paraquat via the dermal route

Phthalimide Analogs Enhance Genotoxicity of Cyclophosphamide and Inhibit Its Associated Hypoxia

Cyclophosphamide (CP) is a mutagen that is used in cancer chemotherapy, due to its genotoxicity and as an immunosuppressive agent. Thalidomide (TH) is another cancer chemotherapeutic drug. In this study, the cytogenotoxicity and hypoxia modulatory activities of two phthalimide analogs of TH have been evaluated with/without CP. Both analogs have increased CP-stimulated chromosomal aberrations than those induced by TH, including gaps, breaks/fragments, deletions, multiple aberrations, and tetraploidy. The analogs have elevated the cytotoxic effect of CP by inhibiting the mitotic activity, in which analog 2 showed higher mitosis inhibition. CP has induced binucleated and polynucleated bone marrow cells (BMCs), while micronuclei (MN) are absent. TH and analogs have elevated the CP-stimulated binucleated BMCs, while only analogs have increased the CP-induced polynucleated BMCs and inhibited the mononucleated BMCs. MN-BMCs were shown together with mononucleated, binucleated, and polynucleated cells in the CP group. Both analogs have elevated mononucleated and polynucleated MN-BMCs, whereas in presence of CP, TH and analogs have enhanced mononucleated and binucleated MN-BMCs. The analogs significantly induce DNA fragmentation in a comet assay, where analog 1 is the strongest inducer. The treatment of mice with CP has resulted in a high hypoxia status as indicated by high pimonidazole adducts and high HIF-1α and HIF-2α concentrations in lymphocytes. Analogs/CP-treated mice showed low pimonidazole adducts. Both analogs have inhibited HIF-1α concentration but not HIF-2α. Taken together, the study findings suggest that both analogs have a higher potential to induce CP-genotoxicity than TH and that both analogs inhibit CP-hypoxia via the HIF-1α-dependent mechanism, in which analog 1 is a more potent anti-hypoxic agent than analog 2. Analog 1 is suggested as an adjacent CP-complementary agent to induce CP-genotoxicity and to inhibit CP-associated hypoxia.

Evaluation of carcinogenic activities and sperm abnormalities of Gram-negative bacterial metabolites isolated from cancer patients after subcutaneous injection in albino rats

Microbial pathogens drive tumorigenesis in 20% of cancer cases, so the present study is aimed to evaluate the carcinogenic activities, sperm abnormalities and other dangerous effects of the subcutaneous injection of extracts obtained from various clinical Gram-negative bacteria derived from cancer patients using albino rats. We isolated, identified and extracted of their secondary metabolites of carbapenem resistant Gram-negative bacteria derived from cancer patients. Various methods have been used to determine hepatotoxicity, nephrotoxicity, tumorigenesis, inflammatory and sperm abnormalities in the albino rats injected with extracts. In comparison with the normal animals group, all extracts induced hepatotoxicity which was evidenced by the significant elevation in the activity of the serum alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase and alkaline phosphatase; also, nephrotoxicity that was indicated through the marked increase in the serum urea and creatinine levels; tumorigenesis was achieved from the sharp elevation in serum levels of alpha fetoprotein, carcinoembryonic antigen and lactate dehydrogenase values as tumor markers; as well as severe inflammatory characteristics were monitored from the marked raise of tumor necrosis factor alpha and interleukin-1beta. Furthermore, the proportion of micronuclei in polychromatic erythrocytes and sperm abnormalities were statistically significant in all groups compared to control group. Various kinds of head abnormalities and coiled tail were noted. Histopathological examination of hepatic tissue came in line with the biochemical and cytological findings. It could conclude that the extracts of Serratia sp. Esraa 1, Stenotrophomonas sp. Esraa 2, Acinetobacter sp. Esraa 3, Escherichia sp. Esraa 4 and Pseudomonas sp. Esraa 5 were able to initiate cytotoxicity and tumorigenesis in rats.

Evaluation of lapatinib cytotoxicity and genotoxicity on MDA-MB-231 breast cancer cell line

Lapatinib, one of the tyrosine kinase inhibitors (TKIs), is used to reduce epidermal growth factor family proteins overexpression. This study aims to assess the cytotoxic and genotoxic effects of lapatinib on the triple negative breast cancer cell line "MDA-MB-231". We investigated the cytotoxicity of lapatinib by MTT assay, mode of cell death using apoptosis-necrosis assay, DNA damage using micronucleus test, EGFR protein expression by immunocytochemistry, and assessed its effect on EGFR (7p11.2 locus) and TP53 (17p13 locus) genes using interphase-FISH technique. Lapatinib induced cytotoxicity on MDA-MB-231 cell line by elevating the concentration and its IC₅₀ value was 32.5 μM after 24 h. Lapatinib increased apoptotic cells and micronuclei in binucleated cells gradually by increasing the concentration for 24 h. The EGFR protein expression was reduced by double fold that expressed in non-treated cells. Lapatinib enhanced deletion of EGFR gene signals highly significantly from the lowest concentration. Alternatively, lapatinib amplified signals of TP53 gene effectively by raising the concentration. In conclusion, lapatinib induced cytotoxic and genotoxic effects on MDA-MB-231 cell line. However, laptinib reduced the EGFR protein expression and EGFR signals, it raised the apoptotic cells and TP53 gene signals, which triggered extensive DNA damage. Therefore, lapatinib is an effective TKI in triple negative breast cancer cells as elucidated by its mode of cell death.

Carcinogenic Activities and Sperm Abnormalities of Methicillin Resistance Staphylococcus aureus and Inhibition of Their Virulence Potentials by Ayamycin

This investigation aimed to study the in vivo harmful effects of the subcutaneous injection of different methicillin resistance Staphylococcus aureus extracts (MRSA2, MRSA4, MRSA10, MRSA69, MRSA70, MRSA76, and MRSA78). Such strains represented the highest minimum inhibition concentration toward methicillin with various multidrug-resistant patterns. The obtained results revealed that rats injected with the MRSA4 extract died immediately after the last dose indicating the high cytotoxicity of MRSA4 strain (100% mortality). While the mortalities in other groups injected by the other MRSA extracts ranged from 50 to 75%. In comparison with the normal animal group, all MRSA extracts induced a hepatotoxic effect which was indicated from the significant (p < 0.01) increases in the activities of the serum alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT) enzymes. Moreover, alkaline phosphatase (ALP) combined with a partial nephrotoxicity that was monitored from the significant elevation of serum urea concentration. While serum creatinine levels did not affect. Similarly, a significant elevation was recorded in serum levels of tumor biomarkers (alpha fetoprotein; AFP, carcinoembryonic antigen; CEA, and lactate dehydrogenase; LDH) reflecting their carcinogenic potential. On the other hand, the percentage of micronuclei (MN) in polychromatic erythrocytes from bone marrow cells was statistically significant in all groups as compared to the control group. The percentage of sperm abnormalities was statistically significant compared to the control. Different types of head abnormalities and coiled tail were recorded. Consequently, the current study focused on fighting MRSA virulence factors by the new compound ayamycin, which proved to be potent anti-virulence factor against all MRSA strains under study by significant decreasing of their streptokinase activities, hemolysin synthesis, biofilm formation, and their cell surface hydrophobicity.

Optimized ultra performance liquid chromatography tandem high resolution mass spectrometry method for the quantification of paraquat in plasma and urine

A simple, sensitive and specific ultra performance liquid chromatography coupled to electrospray tandem high resolution mass spectrometry (UPLC-ESI-HRMS/MS) method has been developed and validated for quantification of paraquat in plasma and urine. The sample preparation was carried out by one-step protein precipitation with acetonitrile. The paraquat was separated with a HILIC column in 10min. Detection was performed using Q Exactive Orbitrap mass spectrometer by Targeted-MS/MS scan mode. Methodological parameters, such as ammonium formate concentration, formic acid concentration, spray voltage, capillary temperature, heater temperature and normalized collision energy were optimized to achieve the highest sensitivity. The calibration curve was linear over the concentration range of LOQ-1000ng/mL. LOD was 0.1 and 0.3ng/mL, LOQ was 0.3 and 0.8ng/mL for urine and plasma, respectively. The intra- and inter-day precisions were <7.97% and 4.78% for plasma and urine. The accuracies were within the range 93.51-100.90%. The plasma and urine matrices had negligible relative matrix effect in this study. This method was successfully applied to determine paraquat concentration in plasma samples with hemoperfusion from 5 suspected paraquat poisoning patients.

In vivo evaluation of the genotoxic effects of gonadotropins on rat reticulocytes

BACKGROUND

Gonadotropins, as ovulation-inducing drugs, have been used widely to treat infertility. An epidemiologic correlation between infertility therapy and ovarian cancer development has been reported. However, the effect of gonadotropins in the formation of reproductive tract cancers is controversial.

OBJECTIVE

The aim of the study was to determine the in vivo genotoxic effects of gonadotropins on rat reticulocytes.

METHODS

In this prospective, randomized, controlled study, rats were randomly assigned to 1 of 5 groups. The calculated rat doses of 0.65 human menopausal gonadotropin (hMG), 0.95 hMG, 0.65 follitropin beta (FB), 0.95 FB, or normal saline (control group) were injected, respectively. These calculated rat doses (U/g) are based on average human gonadotropin doses of 150 and 225 IU/d for a 70-kg woman given in 2-mL saline (the control group received 2 mL of saline). Injections were administered once per day for 5 days, followed by 5 days of rest. Each treatment was repeated for 6 estrus cycles in the rats for a total of 12 estrus cycles. Six months after the last day of the 12(th) cycle, the rats were euthanized. Bone marrow tissues were removed, and pluripotent reticulocyte cells with micronuclei, nuclear buds, and binuclear abnormalities were analyzed using an in situ micronuclei assay under light microscopy. The proportion of micronucleated cells, cells with anaphase bridge, nuclear buds, and other nuclear abnormalities were measured.

RESULTS

The number of cells with nuclear buds and binuclear abnormalities in the hMG 225 and FB 225 groups was significantly higher (P < 0.05) than that from the hMG 150, FB 150, and control groups in the cytogenetic analysis of bone marrow stem cells. An increased rate of genotoxicity in all gonadotropin groups versus that of placebo was found.

CONCLUSION

In rats, the micronucleus genotoxicity assay suggests a dose-dependent gonadotropin effect on genomic instability in bone marrow stem cells in vivo.

Antimutagenic effect of Origanum majorana L. essential oil against prallethrin-induced genotoxic damage in rat bone marrow cells

This study aimed to investigate the genotoxic and cytotoxic potential of prallethrin in rat bone marrow cells and the protective effect of Origanum majorana L. essential oil (EO). Our results demonstrated that prallethrin at dose 64.0 mg/kg body weight (b.wt.) (1/10 LD50), has a clastogenic/genotoxic potential as shown by the high percentage of chromosomal aberration (CA) and micronucleus (MN) in the bone marrow cells of male rats, whereas the combined treatment of prallethrin and O. majorana EO resulted in the reduction of the CA (54.54%). The combined treatment also reduced the micronuclei formation significantly. In conclusion, prallethrin can be considered clastogenic/genotoxic and may carry a risk to human health. The study revealed the antigenotoxic and anticytotoxic potential of O. majorana EO against prallethrin-induced genotoxic and cytotoxic effects in rat bone marrow cells.

Anti-genotoxic effect of the Sargassum dentifolium extracts: prevention of chromosomal aberrations, micronuclei, and DNA fragmentation

The alga Sargassum dentifolium (Turner) C. Agardh, belongs to Sargassaceae, is a brown seaweed in red sea shores in Egypt. This work aimed to extract different water-soluble polysaccharide extracts (E1, E2, and E3) from S. dentifolium and to investigate their protective effect against cyclophosphamide (CP)-induced genotoxicity. Mice bone marrow cells (BMCs) were collected and analyzed for the chromosomal aberration, micronucleated BMCs (MN-BMCs), the mitotic index, DNA fragmentation by comet assay, and histone deacetylases (HDACs), and radical scavenging capacity of extracts was evaluated by the oxygen radical absorbance capacity assay. The results indicated that E2 and E3 significantly inhibited CP-induced multiple chromosomal aberrations, where E1 and E3 significantly suppressed the number of CP-induced formation of tetraploidy. The extracts prohibited the cytotoxic effect of CP and recovered the mitotic activity, whereas E1 possessed the highest recovery and mitosis. In absence of MN, CP induced formation of bi- and poly-nucleated BMCs. E1 prohibited CP-induced formation of bi-nucleated BMCs, while E2 and E3 prohibited CP-induced formation of poly-nucleated BMCs. CP-induced MN-BMCs were accompanied with mono-, bi- and poly-nucleated cells. E1 and E3 remarkably suppressed mono-nucleated MN-BMCs, while E2 inhibited bi-nucleated MN-BMCs. All the extracts significantly inhibited the CP-induced formation of poly-nucleated MN-BMCs. CP-induced DNA fragmentation was inhibited by all extracts, where E1 was the strongest inhibitor as concluded from the comet tail moment. All the extracts were strong OH scavengers, while only E3 was ROO scavenger. The results revealed a drastic decline in HDACs activity by E1 and E3. In conclusion, S. dentifolium polysaccharide extracts E1 and E3 possessed a potential anti-genotoxic and a promising anti-mutagenic activity.

Heart tissue of harlequin (hq)/Big Blue mice has elevated reactive oxygen species without significant impact on the frequency and nature of point mutations in nuclear DNA

Age is a major risk factor for heart disease, and cardiac aging is characterized by elevated mitochondrial reactive oxygen species (ROS) with compromised mitochondrial and nuclear DNA integrity. To assess links between increased ROS levels and mutations, we examined in situ levels of ROS and cII mutation frequency, pattern and spectrum in the heart of harlequin (hq)/Big Blue mice. The hq mouse is a model of premature aging with mitochondrial dysfunction and increased risk of oxidative stress-induced heart disease with the means for in vivo mutation detection. The hq mutation produces a significant downregulation in the X-linked apoptosis-inducing factor gene (Aif) impairing both the antioxidant and oxidative phosphorylation functions of AIF. Brain and skin of hq disease mice have elevated frequencies of point mutations in nuclear DNA and histopathology characterized by cell loss. Reports of associated elevations in ROS in brain and skin have mixed results. Herein, heart in situ ROS levels were elevated in hq disease compared to AIF-proficient mice (p<0.0001) yet, mutation frequency and pattern were similar in hq disease, hq carrier and AIF-proficient mice. Heart cII mutations were also assessed 15 days following an acute exposure to an exogenous ROS inducer (10 mg paraquat/kg). Acute paraquat exposure with a short mutant manifestation period was insufficient to elevate mutation frequency or alter mutation pattern in the post-mitotic heart tissue of AIF-proficient mice. Paraquat induction of ROS requires mitochondrial complex I and thus is likely compromised in hq mice. Results of this preliminary survey and the context of recent literature suggest that determining causal links between AIF deficiency and the premature aging phenotypes of specific tissues is better addressed with assay of mitochondrial ROS and large-scale changes in mitochondrial DNA in specific cell types.

Cytotoxic and genotoxic effects of paraquat in Hordeum vulgare and human lymphocytes in vitro

Two phylogenetically distant types of test-systems-root tip meristems of barley (Hordeum vulgare) and human lymphocytes in vitro were used to detect genotoxicity and cytotoxicity induced by the herbicide paraquat (PQ) in the concentration range (10(-6) to 5 x 10(-4) mol/l). As an endpoint for cytotoxicity the mitotic index (MI) was evaluated. The frequency of chromosome aberrations (CA) and the frequency of micronuclei (MN) were used as endpoints for genotoxicity. A dose-dependent increase of CA and MN was observed in both test systems, although the values for PQ-induced MN were somewhat lower. The increase of the genotoxic effect corresponds to a decrease of mitotic activity. The structurally reconstructed barley karyotype MK14/2034 allowed the allocation of the PQ-specific features of aberration distribution patterns and gave information about which chromosome segments in different chromosomal positions were involved in induced aberrations. Paraquat produced preferably isochromatid breaks and "aberration hot spots" in a restricted number of heterochromatin-containing segments. The comparative analysis of susceptibility in the used test-systems to PQ with respect to its cytotoxic and clastogenic effect showed that the human lymphocytes were more sensitive than Hordeum vulgare.

Studies of the interaction between paraquat and bovine hemoglobin

The interaction between paraquat (PQ) and bovine hemoglobin (BHb) was investigated using fluorescence and UV/vis absorption spectroscopy. The reactivity of the heme centers with superoxide anions formed by PQ was judged on the basis of the decrease of the Soret band. The experimental results showed that the fluorescence quenching of BHb by PQ was a result of the formation of PQ-BHb complex; static quenching was confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K(A) and corresponding thermodynamic parameters were measured at different temperatures. The process of binding PQ molecule on BHb was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The effect of PQ on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy.

In vivo Evaluation of the Genotoxic Effects of Clomiphene Citrate on Rat Reticulocytes: A Micronucleus Genotoxicity

OBJECTIVE

To determine the genotoxic effects of clomiphene citrate (CC) on rat reticulocytesin vivo.

METHODS

In this prospective, randomized, controlled study, rats were each assigned randomly to the CC 50, CC 100, CC 200, or control group and were given repeat doses of 0.16, 0.32 or 0.64 mg CC, or normal saline, respectively. Each study group received its CC dose in 2 ml of saline intraperitoneally for 5 days, while the control group received only 2 ml of saline. Each treatment cycle was repeated six times. Six months later, the rats were euthanized. Bone marrow tissues were removed, and pluripotent reticulocyte cells with micronuclei, nuclear buds, and binuclear abnormalities were analyzed using an in situmicronuclei assay under light microscopy. The proportion of micronucleated erythrocytes was measured.

RESULTS

Fewer cells with nuclear buds and binuclear abnormalities were detected in the CC 50 group and controls. The CC 100 and 200 groups had significantly (p < 0.05) more nuclear buds and binuclear abnormalities compared with the CC 50 group and controls in the cytogenetic analysis of bone marrow stem cells.

CONCLUSION

In rats, the micronucleus genotoxicity assay suggests a dose-dependent CC effect on genomic instability in bone marrow stem cells in vivo.