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

Exploring cytokinesis block micronucleus assay in Croatia: A journey through the past, present, and future in biomonitoring of the general population

In this study, we used the cytokinesis-block micronucleus (CBMN) assay to evaluate the background frequency of cytogenetic damage in peripheral blood lymphocytes of the general population concerning different anthropometric data and lifestyle factors. The background frequency of CBMN assay parameters was analysed in 850 healthy, occupationally non-exposed male and female subjects (average age, 38±11 years) gathered from the general Croatian population from 2000 to 2023. The mean background values for micronuclei (MNi) in the whole population were 5.3±4.3 per 1000 binucleated cells, while the mean frequency of nucleoplasmic bridges (NPBs) was 0.7±1.3 and of nuclear buds (NBUDs) 3.1±3.2. The cut-off value, which corresponds to the 95th percentile of the distribution of 850 individual values, was 14 MNi, 3 NPBs, and 9 NBUDs. Results from our database also showed an association of the tested genomic instability parameters with age and sex but also with other lifestyle factors. These findings underscore the importance of considering several anthropometric and lifestyle factors when conducting biomonitoring studies. Overall, the normal and cut-off values attained here present normal values for the general population that can later serve as baseline values for further human biomonitoring studies either in Croatia or worldwide.

Meta-analysis of chromosomal aberrations as a biomarker of exposure in healthcare workers occupationally exposed to antineoplastic drugs

Many antineoplastic drugs used to treat cancer, particularly alkylating agents and topoisomerase inhibitors, are known to induce genetic damage in patients. Elevated levels of chromosomal aberrations, micronuclei, and DNA damage have been documented in cancer patients. Elevations in these same biomarkers of genetic damage have been reported in numerous studies of healthcare workers, such as nurses and pharmacists, who routinely handle these drugs, but results vary across studies. To obtain an overall assessment of the exposure effect, we performed a meta-analysis on data obtained from peer-reviewed publications reporting chromosomal aberration levels in healthcare workers exposed to antineoplastic drugs. A literature search identified 39 studies reporting on occupational exposure to antineoplastic drugs and measurement of chromosomal aberrations in healthcare workers. After applying strict inclusion criteria for data quality and presentation, data from 17 studies included in 16 publications underwent meta-analysis using Hedges' bias-corrected g and a random-effects model. Results showed the level of chromosomal aberrations in healthcare workers exposed to antineoplastic drugs was significantly higher than in controls. The standardized mean differences (difference of means divided by within sd) from all studies were pooled, yielding a value 1.006 (unitless) with p<0.001. Thus, in addition to the documented genotoxic effects of antineoplastic drugs in cancer patients, this meta-analysis confirmed a significant association between occupational exposure to antineoplastics during the course of a normal work day and increases in chromosomal aberrations in healthcare workers. Based on the studies reviewed, we were unable to accurately assess whether appropriate use of protective measures might reduce the incidence of genetic damage in healthcare workers. However, given the potential for increased cancer risk linked to increases in chromosomal aberrations, the results of this study support the need to limit occupational exposure of healthcare workers to antineoplastic drugs as much as possible.

Acute Taxol nephrotoxicity: Histological and ultrastructural studies of mice kidney parenchyma

Taxol is a microtubule inhibitor drug widely used in treatment of many types of cancer. Nephrotoxicity is the most hazardous effect complicating chemotherapy in general and kidney functions must be monitored early during any chemotherapeutic course. The main objective of the present study was to investigate the effect of acute Taxol nephrotoxicity in mice. In the present study Taxol at different doses; MD, ID and MTD (0.6, 1.15 and 1.7 mg/kg), respectively, was given by intra-peritoneal route to 54 adult male mice with an average body weight of 20-25 g. Kidney samples was taken 6, 24, 48 h following administration, fixed in 10% neutral buffered formalin, paraffin sections 5 μm thick were stained by haematoxylin and eosin and PAS and then examined for histological changes. Samples from animals treated by the maximum dose (MTD = 1.7 mg/kg) for 48 h were fixed in 3% gluteraldehyde in phosphate buffer (pH 7.4) and processed for transmission electron microscope. Taxol given for short duration was found to produce marked degenerative changes in kidney parenchyma even in minimum tolerated dose (MD = 0.6 mg/kg). Individual variations were observed regarding the degree of nephrotoxicity. There was marked loss of renal tubules epithelial lining, damage of brush border and formation of hyaline casts within the damaged tubules. The alterations were in the form of both necrotic and apoptotic changes in the kidney tubules. Focal atrophy of glomerular tufts was also observed. Vascular congestion and degenerative changes in renal blood vessels were occasionally evident in some samples. Ultrastructure study revealed damage of glomerular membrane. Proximal tubule showed loss of basal infoldings, damage of brush border, mitochondrial degeneration and nuclear changes. Distal tubules also showed demarked degenerative changes. Increased frequency of micronuclei proved that Taxol had genotoxic effects in mice bone marrow cells. In conclusion Taxol had nephrotoxic effect on mice kidney that must be considered during its use as a chemotherapeutic agent in human.

DNA damage in lymphocytes and buccal mucosa cells of children with malignant tumours undergoing chemotherapy

The aim of the present study was to evaluate DNA damage (micronucleus) in cytokinesis-blocked lymphocytes and exfoliated buccal mucosa cells from children with malignant tumours and under chemotherapy. Micronucleated cells (MNCs) were assessed from children before and during chemotherapy. A total of 21 healthy children (controls), matched for gender and age, were used as control. The results pointed out higher frequencies of micronucleated lymphocytes in children with malignant tumour before any therapy when compared to healthy probands. Furthermore an increase of micronucleated lymphocytes during chemotherapy was detected when compared to the data obtained before chemotherapy. No statistically significant increases of MNCs were noticed in buccal mucosa cells at any of the timepoints evaluated. Taken together, these data indicate that the presence of malignant tumours may increase the frequency of DNA damage in circulating lymphocytes, these cells being more sensitive for detecting chromosome aberrations caused by anti-cancer drugs.

Micronucleus induction and FISH analysis in buccal cells and lymphocytes of nurses administering antineoplastic drugs

A genotoxic effect for antineoplastic drugs, in particular micronucleus induction, has been shown in several studies. The aim of our study was to assess genotoxic effects in nurses administering different mixtures of antineoplastic drugs in an oncology hospital by evaluating the frequency of micronuclei in exfoliated buccal cells and blood lymphocytes by use of the standard micronucleus (MN) test and by identifying, by means of FISH analysis with centromeric probes, the mechanism of micronucleus induction (clastogenic or aneugenic). The study group comprised 23 nurses, 10 of whom worked in the day-care hospital and 13 in the ward. Twenty healthy subjects were selected as controls. Pan-centromeric FISH analysis was performed on lymphocytes from a selected group of nurses (12/23 subjects) characterized by higher MN frequencies as observed by standard Giemsa staining. A significant increase of micronucleus frequency compared with controls was found in exfoliated buccal cells of both groups of nurses: day-care hospital nurses 0.92 versus 0.45 (p=0.034) and ward nurses 0.94 versus 0.45 (p=0.051). An increase, although not statistically significant, of mean MN frequency was also found by the MN standard test on lymphocytes of the day-care hospital nurses (10.9 versus 7.5; p=0.056), while no differences were found in ward nurses (8.15 versus 7.5; p=0.56). We found that the administration of antineoplastic drugs by nurses in ward units induced a higher frequency of FISH MN+ (43% of subjects) than in the day-care hospital (20%). This was associated with the micronucleus size percentage. This finding could be correlated with the different compositions of administered mixtures of antineoplastic drugs: in ward units the mixtures contained drugs, such as vinorelbine, that were absent in the mixtures administered in the day-care hospital. Our results show genetic damage induced by administration of antineoplastic drugs, particularly in exfoliated buccal cells. This result suggests the useful application of this non-invasive sampling to evaluate genotoxic effects of occupational exposure to mixtures of inhalable chemicals at low doses.

Cytokine-induced killer cells against autologous CLL: direct cytotoxic effects and induction of immune accessory molecules by interferon-gamma

Cytokine-induced killer cells (CIK cells), coexpressing CD3 and CD56, can be expanded from peripheral blood mononuclear cells by the timed addition of interferon-gamma (IFN-gamma), IL-2 and OKT3. The effects of CIK cells on primary, autologous CLL cells are described. We used MACS to separate CD3(+) cells for expansion of CIK cell effectors and CD19(+) targets from peripheral blood of 16 CLL patients. Apoptosis was assessed by measuring annexinV staining in CLL cells. After incubation of autologous CIK with CLL, specific apoptosis in CLL cells was 15%. Coincubation with irradiated CIK cells for 48 hr before adding vital CIK cells resulted in an increased ICAM-1 expression on CLL cells and an increase in apoptosis of CLL targets (30%). These effects were mediated by IFN-gamma secretion of CIK cells. In addition to their direct cytotoxic effect, CIK cells secrete IFN-gamma that modulates the expression of adhesion molecules on CLL cells, and this enhances apoptosis induction by cytotoxic effector cells.

Cytogenetic damage in lymphocytes of patients undergoing therapy for small cell lung cancer and ovarian carcinoma

The level of cytogenetic damage in peripheral blood lymphocytes of patients undergoing chemotherapy has been analyzed incisively 20 years ago. The results showed that the highest level of cytogenetic damage was observed at the end of therapy. In recent years, the doses of anticancer drugs were intensified thanks to the discovery of colony stimulating factors. Therefore, it was interesting to analyze the kinetics of micronuclei formation in lymphocytes of patients undergoing modern chemotherapy. The frequencies of micronuclei were measured in lymphocytes of 6 patients with small cell lung cancer treated with a combination of cisplatin and etoposide and 7 patients with ovarian carcinoma treated with a combination of taxol and cisplatin. 3 patients with lung cancer received radiotherapy in addition to chemotherapy. Micronuclei were analyzed in lymphocytes collected before the start of therapy and 1 day before each following cycle of chemotherapy. The micronucleus frequencies were compared with the kinetics of leukocyte counts. The micronucleus frequencies showed an interindividual variability. On average, the frequencies of micronuclei increased during the first half of therapy and declined thereafter, reaching, in some patients with ovarian carcinoma, values below the pre-treatment level. Leukocyte counts decreased strongly at the beginning of therapy with an upward trend at the end. We suggest that the decline of micronuclei was due to repopulation of lymphocytes and acquired drug resistance.