Genotoxic activity of L-asparaginase produced by Streptomyces ansochromogenes UFPEDA 3420.

L-asparaginase is an enzyme capable of hydrolyzing the substrate asparagine in aspartic acid and ammonia. Due to this mechanism of action observed, L-asparaginase is widely used in the treatment of Acute Lymphoblastic Leukemia, since these cells use asparagine for their survival. Because it is frequently used as an antineoplastic, it is necessary to evaluate its genotoxic effects. The aim of the present study was to evaluate cellular DNA damage after exposure to L-asparaginase produced by Streptomyces ansochromogenes UFPEDA 3420. NCIH-292, MCF-7 and MOLT-4 neoplastic cell lines and normal PBMC cells were used. L-Asparaginase used in this study was produced by actinobacteria S. ansochromogenes UFPEDA 3420, isolated and purified by chromatographic methods. L-Asparaginase induced micronucleus formation in PBMC cells and tumor lines when compared to the negative control. These data suggest that L-Asp appears to have a genotoxic effect very close to the positive control in normal cells (p < 0.05). The level of genomic damage measured by DNA breaks in alkaline SCGE assay was detected from the lowest concentration (12.5 µg/mL) to the highest concentration (50 µg/mL) for tumor cell lines and PBMC. In view of the above, new genotoxic studies will be carried out to better elucidate L-Asparaginase and its mutagenic potential, still unknown, enough for this drug to be safely used in conventional antineoplastic therapies.

Assessment of the association between micronuclei and the degree of uterine lesions and viral load in women with human papillomavirus.

Infection by human papillomavirus (HPV) is among the main etiologies of cervical cancer. The expression of oncogenic viral proteins enables the onset of the virus, which can trigger the carcinogenic process. One of the main characteristics of this process is the loss of genome stability, including chromosome stability. The micronucleus test is a cytogenetic method for the detection of genetic alterations that change chromosome behavior during cell division resulting in the formation of micronuclei. This method has been applied for the early detection of DNA damage in individuals with a greater likelihood of developing cancer. The aim of the present study was to assess the association between micronucleus expression and the degree of cytological lesions and viral load in patients with HPV. The micronucleus analysis revealed differences in the number micronuclei found in the groups, which ranged from 0.00067 to 0.00133 in the control group and 0.00267 to 0.02433 among patients with HPV. Statistically significant differences (p<0.05) were found in the number of micronucleated cervical cells between the patients and healthy women. Moreover, significant associations were found between micronucleus expression and both the degree of uterine lesions (r2=0.7237; r=0.8507; p=0.000002) and viral load (r2=0.7012; r=0.8374; p=0.000004). The findings demonstrate the efficacy of micronucleus analysis in monitoring risks to human health.