Spontaneous and gamma-ray-induced sister chromatid exchanges in patients with carcinoma of cervix uteri

Chromosomal radiosensitivity of human immunodeficiency virus positive/negative cervical cancer patients in South Africa

Cervical cancer is the second most common cancer amongst South African women and is the leading cause of cancer-associated mortality in this region. Several international studies on radiation‑induced DNA damage in lymphocytes of cervical cancer patients have remained inconclusive. Despite the high incidence of cervical cancer in South Africa, and the extensive use of radiotherapy to treat it, the chromosomal radiosensitivity of South African cervical cancer patients has not been studied to date. Since a high number of these patients are human immunodeficiency virus (HIV)‑positive, the effect of HIV infection on chromosomal radiosensitivity was also investigated. Blood samples from 35 cervical cancer patients (20 HIV‑negative and 15 HIV‑positive) and 20 healthy controls were exposed to X‑rays at doses of 6 MV of 2 and 4 Gy in vitro. Chromosomal radiosensitivity was assessed using the micronucleus (MN) assay. MN scores were obtained using the Metafer 4 platform, an automated microscopic system. Three scoring methods of the MNScore module of Metafer were applied and compared. Cervical cancer patients had higher MN values than healthy controls, with HIV‑positive patients having the highest MN values. Differences between groups were significant when using a scoring method that corrects for false positive and false negative MN. The present study suggested increased chromosomal radiosensitivity in HIV-positive South African cervical cancer patients.

Sister chromatid exchange: A possible approach to characterize familial breast cancer patients

Sister chromatid exchange (SCE) frequency is widely used as an indicator of spontaneous chromosome instability. We investigated SCE frequency in the peripheral blood lymphocytes of familial and sporadic breast cancer (BC) patients from the Apulian Caucasian Population. Eighty-one patients were enrolled: 22 with familial history and 59 sporadic patients. Eleven familial patients had an 'increased risk' of BRCA gene mutation (BRCAPro ≥ 10%) and were candidates for BRCA1 and BRCA2 mutation analysis. For these reasons, we stratified the 22 familial BC patients in two group: 'low-risk' (n=11) and 'high-risk' (n=11) patients for BRCA gene mutations. Two of these 11 'high-risk' patients (18%) had pathogenic mutations in the BRCA2 gene. The subjects were not cigarette smokers or alcohol or drug users, and had no genetic disorders or chronic diseases affecting the family. Our results showed a significant increase in SCE frequency in the familial (5.305 ± 1.088/metaphase) (P<0.0001) and the sporadic patients (3.943 ± 0.552) (P<0.0001) compared to the controls (3.197 ± 0.649). We found that the SCE frequency was always significantly higher in familial than in sporadic patients, regardless of their clinicopathological characteristics. Moreover, we observed that the frequency of SCE in BRCA2 mutation carrier patients was higher compared to patients without mutations in BRCA1/2 genes. These findings highlight an intrinsic genomic instability in familial patients, and we suggest that SCE frequency may be used as a biomarker to better characterize familial BC.

Genotoxicity of barley stripe mosaic virus in infected host plants

A comparative study of the effect of barley stripe mosaic virus (BSMV) and gamma irradiation on mitotic divisions in barley (Hordeum vulgare L.) roots was performed by evaluating the mitotic index (MI), micronucleus (MN) frequency and sister chromatid exchanges (SCE). Results indicate that, similarly to gamma irradiation at doses of 100, 150 and 250 Gy, BSMV reduces the mitotic activity, increases the micronucleus frequency and the rate of SCE and promotes the formation of C-metaphases. In root meristematic cells of the three barley cultivars studied (Galactic, Sonor and Unirea), the mitotic index of infected plants was found to be 52.5, 54.48 and 64.17%, respectively, lower than the uninfected control. An increase in frequency of sister chromatid exchanges was observed in all the experimental variants. In treatments involving viral infection alone or in combination with gamma irradiation chromosomes with three and more chromatid exchanges were observed, while their percentage in the control or in treatments with gamma irradiation alone was reduced. The results of the study indicate that in plants derived from irradiated seeds, BSMV produces an effect that is correlated nonlinearly with the radiation dose applied. Cytological analysis of mitotic divisions in barley roots revealed the genotoxicity of BSMV infection.