Comparison of the effects of weakened mutagens of chemical Mitomycin C and physical UV on the genomes of lymphocytes

The worst effect of mutagens on the human genome is making the basis of some disorders. Mitomycin C (MMC) and UV are the mutagens which are used in health centers but their effects on genome are unclear. In this study the effects of these mutagens (weakened based on the mitotic index) on the genomic instability were compared. 105 lymphocytes separated with ficol, were cultured in T25 flask contained 5ml F12 with 15%-20%FCS, mitogen PHA (phytohemaglutinin) and BrdU (BromodeoxyUridine). Three flasks contained MMC with concentrations of 3ng/ml, 6ng/ml and 9ng/ml and two flasks were irradiated with UV (20 cm from the UV-C lamp of 420 LUX) for 3 or 5 minutes. The control flask had the same number of lymphocytes but no treatment. The flasks were incubated in 37Co and the metaphasic cells were halted in metaphasic stage after 72 hours with colchicine and stained by the SCE (sister chromatid exchange) method then the average of sister chromatid exchange was evaluated in one hundred metaphasic plaques. Study of the slides revealed an increase of SCE in all specimens in comparison with control. While the rate of SCE was 3.35 percent in the control group it was 5.43, 7.1, and 8.13 in MMC treated cells with the concentrations of 3ng/ml, 6ng/ml and 9ng/ml respectively. The rate of SCE was 4.43 and 6.8 percent in irradiated cells with UV for 3 and 5 minutes respectively. The differences with the control group were significant (P<0.001). The results indicated that the weakened chemical and physical mutagens cause genomic instability. MMC used in chemotherapy at high dose, can cause genomic instability in the normal cells and prepare them for mutation. Also short time radiation of UV didn’t prevent mutagenic effect. As this ray may be in atmosphere due to destruction of ozone, it could be a risk factor for human in the future. This research displayed the importance of weakened mutagens and revealed the usage rate of MMC and UV to decrease their effects as mutagene.