Cell and Tissue Journal

Abstract Introduction: Heavy metal refers to any metal with relatively high density, with toxic effects even at ppb levels. Heavy metals are one of the main threats to human health. Arsenic (As) is a heavy metal found in our living environment due to its widespread use in industrial activities. Exposure to As and its absorption by different tissues may lead to damage to cardiovascular function, skin lesions, high blood pressure, and diabetes. As harmful effects on chromosome integrity have been proven a long time ago. It has also been classified as a potent carcinogen by the Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC).  One of the damages caused by As is chromosome breakages. These damages are the result of this heavy metal's ability in producing free radicals and their interaction with the DNA molecule. The role of aneuploidy in cancer induction has been suggested in several investigations. Aneuploidy can lead to drastic changes in the genetic balance of normal cells, potentially forcing them towards cancer formation.
Aims: Due to the close relation between chromosome instability and cancer induction and the ability of As to induce cancer, the question arises whether As can also play a role in chromosome instability? The design of this study is based on answering this question.
Materials and methods: In this study, to analyze potential cell toxicity and chromosome abnormalities induced in different treatments, MTT and Micronucleus assay on Binucleated cells were used, respectively. Cell toxicity of different doses of As was investigated on HDF cells. According to the results of MTT, three non-toxic doses of 100, 200, and 300 ng/ml were selected. To be able to understand the effect of As treatment on chromosome instability induced by aneugenic agent, vinblastine was used. Vinblastine is classified as an aneugen in several studies. Co-treatment of three doses of As and three doses of 0.75, 1.00, and 2.00 ng/ml of vinblastine (Vin) on the induction of chromosome abnormalities was investigated on the HDF cell line using the Micronucleus assay on Binucleated cells.
Results: According to the results of the MTT assay, cell toxicity induced by As at 24, 48, and 72 hours was at doses of 604.3, 397.3, and 228.6, respectively.   As also led to chromosomal abnormalities. Mean frequency of micronucleated binucleates (BiMn) was 0.296, 0497, and 7.270 for 100, 200, and 300 ng/ml, respectively, compared to the frequency of BiMn in the control (0.078). Vinblastine treatment also significantly increased the frequency of BiMn in all doses used compared to the control. Finally, Co-treatment with three doses of vinblastine and three doses of As significantly increased chromosomal abnormalities to almost three to seven times compared to solo vinblastine treatment.
Discussion: Results indicate that As can induce chromosomal abnormalities, which is represented by an increase in BiMn frequency. In addition, co-treatment with vinblastine and As leads to higher chromosomal abnormalities compared to solo treatment with vinblastine. Significant increase in frequency of BiMn in the later experiment suggests that As provides a suitable ground for chromosomal abnormalities induced by other aneugenic agents, here, vinblastine. This effect might be the result of direct interference of As with mechanisms of cell division control or inducing mutation in genes involved in such mechanisms through oxidative species, which leads to an increase in their errors. In both cases, the results of this study reveal an alternative mechanism for As-induced tumor formation.
Conclusion: As not only involves cancer formation by direct damage to chromosomes but also provides a suitable ground for chromosomal mis-segregation in cell divisions, which is believed to be a main step towards cancer formation.  

Abstract Aim: In this study, the genotoxic effect of low frequency electromagnetic wave  that is similar to mobile phones in wavelength, as a main source of producing this waves, in combination with a known aneugen (vinblastine) was investigated on the cultured cells.
Material and Methods: L929 cells were exposed to two forms of continues and discontinues electromagnetic waves with wave length of 900MGh in absence and presence of 1.5 ng/ml of vinblastine for 2 h. Investigation of induced chromosomal abnormalities and cell viability in all treated groups were performed by micronucleus assay on binucleated cells and MTT assay, respectively.
Results: The frequency of micronuclei of cells in continuous and discontinuous electromagnetic fields was significantly higher in comparison with control and cells in turned off electromagnetic field, which represented higher chromosomal aberrations. Co-treatment of the cells with vinblastine did not increase this frequency. Analysis of toxicity showed no decrease in cell viability in all treated groups.
Conclusion: findings represented the ability of electromagnetic field, especially in form of discontinues, in inducing chromosomal abnormality. Also, co-treatment of cells with electromagnetic filed and vinblastine did not elevate the level of chromosome abnormality.
 

Abstract Aim: In this study the effects of stress on induction of structural chromosomal abnormalities on L929 cell line using micronucleus assay on cytokinesis-blocked binucleated cells were investigated in vitro. Material and methods: L929 cells were cultured in DMEM containing 10% FBS. The cells were divided into four groups including; control, 2Gy gamma-irradiated cells, and cells treated with doses of 25, 50 and 100 µg/ml hydrocortisone, and cells co-treated with these three doses of hydrocortisone and irradiation. The treated cells were harvested, stained and chromosome abnormalities were scored using micronucleus assay. Results: Results showed that hydrocortisone did not induce micronuclei as compared to the control group. However, the frequency of micronuclei in cells co-treated with doses of hydrocortisone and irradiation was significantly higher than cells treated only with gamma irradiation (p < 0.05). Conclusion: According to the data of this study, stress hormones are not able to induce any chromosomal abnormalities; however, they are able to increase the cell susceptibility to clastogenic effects of irradiation. Key words: Stress, Hydrocortisone, L929, Gamma ray, Micronucleus