Cytogenetic studies in lymphocytes of patients with rectal cancer

Acute Cytogenetic Effects of Antineoplastic Drugs on Peripheral Blood Lymphocytes in Cancer Patients Chromosome Aberrations and Micronuclei

Aims and Background

The aim of the present study was to evaluate the individual sensitivity of cancer patients to different antineoplastic drugs administered in standard protocols by assessing their acute cytogenetic effects on peripheral blood lymphocytes.

Methods and Study Design

In 12 patients undergoing cancer chemotherapy, acute cytogenetic effects on peripheral blood lymphocytes were evaluated by analysis of structural chromosome aberrations and micronuclei. All patients were given antineoplastic drugs, mainly as polychemotherapy. The frequencies of both cytogenetic biomarkers determined after the first chemotherapy cycle were compared with their pre-treatment (baseline) values.

Results

All chemotherapy protocols employed induced clear cytogenetic effects in both tests studied. The results obtained indicate interindividual variations between cytogenetic damage in peripheral blood lymphocytes among cancer patients. Statistically significant increases in the total number of structural chromosome aberrations and micronuclei in lymphocytes analyzed after chemotherapy compared to pre-therapy samples were observed in almost all patients studied. The highest level of chromosome damage as well as the highest incidence of micronuclei was observed following administration of the ACOP protocol (adriamycin, cyclophosphamide and vincristine). The proportions of signal-positive and signal-negative micronuclei were evaluated using DAPI staining, while silver staining revealed Ag-NOR+ and Ag-NOR− micronuclei. In some patients the incidence of signal-positive and Ag-NOR+ micronuclei after treatment was increased, indicating a more pronounced susceptibility of particular chromosomes to damage caused by antineoplastic drugs.

Conclusions

With regard to the results obtained we may conclude that both parameters used in the present study on peripheral lymphocytes are sensitive biomarkers and can be successfully employed for biomonitoring of acute cytogenetic effects induced by antineoplastic drugs in standard clinical protocols for cancer treatment.

Can consumption of raw vegetables decrease the count of sister chromatid exchange? Results from a cross-sectional study in Krakow, Poland

Background

Sister chromatid exchange (SCE) is a widely used sensitive cytogenetic biomarker of exposure to genotoxic and cancerogenic agents. Results of human monitoring studies and cytogenetic damage have revealed that biological effects of genotoxic exposures are influenced by confounding factors related to life-style. Vegetable and fruit consumption may play a role, but available results are not consistent. The purpose of the study was to investigate the effect of consumption of raw and cooked vegetables and fruits on SCE frequency.

Methods

A total of 62 participants included colorectal cancer (CRC) patients, hospital-based controls and healthy laboratory workers. SCE frequency was assessed in blood lymphocytes. Frequency of vegetable and fruit consumption was gathered by structured semi-quantitative food frequency questionnaire.

Results

SCE frequency was lowest among hospital-based controls (4.4 ± 1.1), a bit higher in CRC patients (4.5 ± 1.0) and highest among laboratory workers (7.4 ± 1.2) (p < 0.05). Multivariable linear regression showed a significant inverse effect (b = −0.20) of raw vegetable consumption, but not so for intake of cooked vegetables and fruits.

Conclusions

The results of the study have shown the beneficial effect of consumption of raw vegetables on disrupted replication of DNA measured by SCE frequency, implying protection against genotoxic agents. Further effort is required to verify the role of cooked vegetables and fruits.

S. U, Yamini, A. P. S. B, Vasudha S. Chromosomal instability in the lymphocytes of breast cancer patients

Genomic instability in the tumor tissue has been correlated with tumor progression. In the present study, chromosomal aberrations (CAs) in peripheral blood lymphocytes (PBLs) of breast tumor patients were studied to assess whether chromosomal instability (CIN) in PBLs correlates with aggressiveness of breast tumor (i.e., disease stage) and has any prognostic utility. Cultured blood lymphocyte metaphases were scored for aberrations in 31 breast cancer patients and 20 healthy age and sex-matched controls. A variety of CAs, including aneuploidy, polyploidy, terminal deletions, acentric fragments, double minutes, chromatid separations, ring chromosome, marker chromosome, chromatid gaps, and breaks were seen in PBLs of the patients. The CAs in patients were higher than in controls. A comparison of the frequency of metaphases with aberrations by grouping the patients according to the stage of advancement of disease did not reveal any consistent pattern of variation in lymphocytic CIN. Neither was any specific chromosomal abnormality found to be associated with the stage of cancer. This might be indicative of the fact that cancer patients have constitutional CIN, which predisposes them to the disease, and this inherent difference in the level of genomic instability might play a role in disease progression and response to treatment.

Chromosomal aberrations in lymphocytes of healthy subjects and risk of cancer

There is evidence that increased frequency of chromosomal aberration (CA) in peripheral blood lymphocytes is a predictor of cancer, but further data are needed to better characterize CA as marker of cancer risk. From the archives of 15 laboratories we gathered cytogenetic records of 11,834 subjects who were free of cancer at the moment of blood drawing and who underwent cytogenetic examination for preventive purposes in the Czech Republic during 1975-2000. We linked these records to the national cancer registry, revealing a total of 485 cancer cases. Subjects were classified according to the percentiles of CA distribution within each laboratory as low (0-33rd percentile), medium (34-66th percentile), and high (66-100th percentile). Subjects were further classified by occupational exposure and by subclass of CA. We found a significant association between the overall cancer incidence and the presence of chromosome-type aberrations [relative risk (RR) for high vs. low CA level = 1.24; 95% confidence interval (CI), 1.03-1.50] but not chromatid-type aberrations. Stomach cancer showed a strong association with frequency of total CA (RR = 7.79; 95% CI, 1.01-60.0). The predictivity of CA observed in subjects exposed to various classes of carcinogens did not significantly differ from the group of nonexposed subjects. This study contributes to validation of CA as a predictive marker of cancer risk, in particular, of stomach cancer; the association between CA frequency and cancer risk might be limited to chromosome-type aberrations.

Assessment of chemotherapy-induced DNA damage in peripheral blood leukocytes of cancer patients using the alkaline comet assay

The alkaline comet assay was employed to assess the pre- and post-treatment levels of in vivo DNA damage in peripheral blood leukocytes of cancer patients. During the study all patients were given antineoplastic drugs, mainly as polychemotherapy. To quantify the DNA damage, two different comet parameters were evaluated: the tail length and the tail moment. Our results indicate marked interindividual variations between baseline DNA damage in peripheral blood leukocytes recorded among cancer patients prior to the chemotherapy. After intravenous administration of various antineoplastic drugs, a significantly increased level of DNA damage in all cancer patients compared to their pre-treatment values was recorded The highest level of DNA damage was seen following administration of 5-fluorouracil, adriamycin, and cisplatin (FAP protocol). The results indicate that administration of antineoplastic drugs in standard protocols is accompanied by significant DNA damage in peripheral blood leukocytes. In order to diminish the potential risks of developing second neoplasms, a continuous biomonitoring of cancer patients after the ending of chemotherapy becomes important. Despite their limitations, present results confirm the usefulness of the alkaline comet assay as a sensitive biomarker of exposure that enables rapid and simple detection of primary DNA damage in peripheral blood leukocytes of cancer patients. Together with standard cytogenetic endpoints, the comet assay provides a powerful technique for the routine detection of critical DNA lesions produced after administration of antineoplastic drugs in the clinical settings.

Bleomycin sensitivity test in the exposed and reference human populations

Sensitivity to bleomycin was investigated in lymphocytes collected from three groups of males: 30 occupationally exposed cokery workers, 38 environmentally exposed Silesian citizen and 35 rural inhabitants. The data were analyzed at both the individual and group levels. The first analysis has revealed a substantial interindividual variability in the level of generated breaks (breaks per cell, b/c). This variability was independent of the age of the donor, smoking habit and X-ray exposure as tested in the multiple regression model. The means per group for the occupationally and environmentally exposed persons were almost the same with the values of 0.674 and 0.639, respectively. These two groups differed significantly from the rural population (b/c=0.448, p<0.001 by MANOVA). The reproducibility of the assay was satisfying (p>0.49 by the Wilcoxon matched paired test) after omitting 7 out of 49 repeatedly sampled donors. Those persons exhibited extremely high b/c rates in the first sampling.