The association between micronucleus, nucleoplasmic bridges, and nuclear buds frequency and the degree of uterine cervical lesions

From WSI-level to patch-level: Structure prior-guided binuclear cell fine-grained detection

Accurate and quick binuclear cell (BC) detection plays a significant role in predicting the risk of leukemia and other malignant tumors. However, manual counting of BCs using microscope images is time consuming and subjective. Moreover, traditional image processing approaches perform poorly due to the limitations in staining quality and the diversity of morphological features in binuclear cell (BC) microscopy whole-slide images (WSIs). To overcome this challenge, we propose a multi-task method inspired by the structure prior of BCs based on deep learning, which cascades to implement BC coarse detection at the WSI level and fine-grained classification at the patch level. The coarse detection network is a multitask detection framework based on circular bounding boxes for cell detection and central key points for nucleus detection. Circle representation reduces the degrees of freedom, mitigates the effect of surrounding impurities compared to usual rectangular boxes and can be rotation invariant in WSIs. Detecting key points in the nucleus can assist in network perception and be used for unsupervised color layer segmentation in later fine-grained classification. The fine classification network consists of a background region suppression module based on color layer mask supervision and a key region selection module based on a transformer due to its global modeling capability. Additionally, an unsupervised and unpaired cytoplasm generator network is first proposed to expand the long-tailed distribution dataset. Finally, experiments are performed on BC multicenter datasets. The proposed BC fine detection method outperforms other benchmarks in almost all evaluation criteria, providing clarification and support for tasks such as cancer screenings.

The synthetic dye malachite green found in food induces cytotoxicity and genotoxicity in four different mammalian cell lines from distinct tissuesw

Malachite green (MG) is a synthetic dye that uses ranges from its application as a tissue dye to that as an antiparasitic in aquaculture. Several studies have reported the presence of this compound in food dyes and in the meat of fish raised in captivity for human consumption, suggesting risks both for the end user and for as those who handle these products because of MG toxic properties described in the literature. Here we evaluated the cytotoxic and genotoxic profiles of MG in four different cell lines (ACP02, L929, MNP01, and MRC-5). Two of these cell lines are stomach cells (normal and cancer lineages) and the potential ingestion of MG makes this a relevant cell type. Cells were treated with MG at concentrations ranging from 0.1 μM to 100 μM, and tested by MTT assay, a differential apoptosis/necrosis assay (EB/OA), the micronucleus test (MN), and the comet assay. MG exhibits dose-dependent cytotoxicity toward all of the tested cell types; higher concentrations of MG cause cell necrosis, while lower concentrations induce apoptosis. MG has a genotoxic profile increasing the rates of micronuclei, nucleoplasmic bridges, nuclear buds, and DNA fragmentation; L929 and MRC-5 showed more sensibility than ACP02 and MNP01.

The Relationship between Telomere Length and Nucleoplasmic Bridges and Severity of Disease in Prostate Cancer Patients

Telomeres are repetitive nucleotide (TTAGGG) sequences that stabilize the chromosome ends and play an important role in the prevention of cancer initiation and progression. Nucleoplasmic bridges (NPBs) are formed when chromatids remain joined together during mitotic anaphase either due to mis-repair of DNA breaks or due to chromatid end fusion as a result of telomere loss or telomere dysfunction. We tested the hypotheses that (i) telomere length (TL) is shorter in prostate cancer (PC) patients relative to healthy age-matched individuals, (ii) TL differs in different stages of PC and (iii) shorter TL is significantly correlated with NPBs formation in PC cases. TL was measured in whole blood by well-established quantitative PCR method and the frequency of NPBs was measured in lymphocytes using cytokinesis-block micronucleus cytome (CBMNcyt) assay. Our results indicate that TL is shorter and NPBs are increased in PC patients relative to age-matched healthy controls. Furthermore, TL was significantly shorter (p = 0.03) in patients with a Gleason score more than 7 and there was also a significant trend of decreasing TL across all three stages (p trend = 0.01; Gleason score <7, 7 and >7). Furthermore, TL was significantly inversely correlated with NPB frequency in PC patients (r = -0.316; p = 0.001) but not in controls (r = 0.163; p = 0.06) and their relationships became stronger with higher Gleason scores. More studies are required that can confirm our observations and explore mechanistic differences in the role of telomeres in NPB formation in PC cases relative to non-cancer cases.

Cadmium exposure and DNA damage (genotoxicity): a systematic review and meta-analysis

Existing literature suggests an association between chronic cadmium (Cd) exposure and the induction of DNA damage and genotoxicity. However, observations from individual studies are inconsistent and conflicting. Therefore current systematic review aimed to pool evidence from existing literature to synthesize quantitative and qualitative corroboration on the association between markers of genotoxicity and occupational Cd exposed population. Studies that evaluated markers of DNA damage among occupationally Cd-exposed and unexposed workers were selected after a systematic literature search. The DNA damage markers included were chromosomal aberrations (chromosomal, chromatid, sister chromatid exchange), Micronucleus (MN) frequency in mono and binucleated cells (MN with condensed chromatin, lobed nucleus, nuclear buds, mitotic index, nucleoplasmatic bridges, pyknosis, and karyorrhexis), comet assay (tail intensity, tail length, tail moment, and olive tail moment), and oxidative DNA damage (8-hydroxy-deoxyguanosine). Mean differences or standardized mean differences were pooled using a random-effects model. The Cochran-Q test and I² statistic were used to monitor heterogeneity among included studies. Twenty-nine studies with 3080 occupationally Cd-exposed and 1807 unexposed workers were included in the review. Cd among the exposed group was higher in blood [4.77 μg/L (-4.94-14.48)] and urine samples [standardized mean difference 0.47 (0.10-0.85)] than in the exposed group. The Cd exposure is positively associated with higher levels of DNA damage characterized by increased frequency of MN [7.35 (-0.32-15.02)], sister chromatid exchange [20.30 (4.34-36.26)], chromosomal aberrations, and oxidative DNA damage (comet assay and 8OHdG [0.41 (0.20-0.63)]) compared to the unexposed. However, with considerable between-study heterogeneity. Chronic Cd exposure is associated with augmented DNA damage. However, more extensive longitudinal studies with adequate sample sizes are necessary to assist the current observations and promote comprehension of the Cd's role in inducing DNA damage.Prospero Registration ID: CRD42022348874.

Role of DNA Repair Deficiency in Cancer Development

The DNA is constantly under attack from endogenous and exogenous damaging agents. The damaged DNA must be repaired quickly to avoid genomic instability and to prevent the occurrence of a malignant transformation. Once a lesion is detected, the DNA repair mechanism initiates and replaces the structurally altered base or any other abnormality. The cell repair mechanisms include direct reversal, excision repair (base excision repair [BER] and nucleotide excision repair [NER]), mismatch repair (MMR), homologous recombination repair (HR) and non-homologous end joining (NHEJ). Unrepaired DNA could lead to mutation, cell death or cancer. This review will discuss how the defects in DNA repair play a vital role in cancer initiation, development and progression.

Association of micronuclear frequency with dysplasia and cytogenetic changes (p53 mutation and p16 expression) in oral potentially malignant disorders

Aims:

The present study evaluated the frequency of micronuclei in oral potentially malignant disorders (OPMDs) and their association with the presence of dysplasia on cytology and biopsy as well as their association with p53 mutation and p16 expression. Cytological findings of dysplastic changes in OPMDs were compared to histological diagnoses.

Material and Methods:

This was a cross-sectional, observational, descriptive study. Scrape smears (n = 74) were collected from lesions in patients with OPMDs. Punch biopsy was collected in patients showing dysplastic changes. Tissue microarray for p53 mutation and p16 expression was performed using paraffin embedded blocks. Cases were classified into grades of dysplasia using both scrape smears and biopsy. Micronuclei frequency was calculated per 100 cells using scrape smears. Mann–Whitney U test was used for correlation of cytology and histology for grade of dysplasia as well as micronuclear frequency with p53 mutation and p16 expression.

Results:

Micronuclear frequency was found to be increased in patients with dysplasia. A significant association of micronuclear frequency with dysplastic changes was seen on cytology. Sensitivity of cytological evaluation was found to be 64.7%. The association of the micronuclear frequency of samples with p53 mutation and p16 expression was nearly significant (n = 28, P = 0.069 and 0.095, respectively).

Conclusion:

Micronuclear frequency can be a reliable marker of mutagenic change in OPMDs. Cytological assessment of micronuclei can serve as useful, non-invasive, and relatively inexpensive tool to predict cancerous changes in OPMDs.

Cytokinesis-block micronucleus cytome (CBMN-CYT) assay and its relationship with genetic polymorphisms in welders

Fumes generated in the welding process are composed of micrometric and nanometric particles that form when metal fumes condense. The International Agency for Research on Cancer established that many compounds derived from the welding process are carcinogenic to humans. Still, there are few studies related to the role of genetic polymorphisms. This work aimed to analyze the influence of OGG1 Ser326Cys, XRCC1 Arg280His, XRCC1 Arg194Thr, XRCC1 Arg399Gln, XRCC3 Thr241Met, GSTM1, and GSTT1 gene polymorphisms on DNA damage of 98 subjects occupationally exposed to welding fumes and 100 non exposed individuals. The results showed that individuals exposed to welding fumes with XRCC3 Thr241Thr, XRCC3 Thr241Met, and GSTM1 null genotypes demonstrated a significantly higher micronucleus frequency in lymphocytes. In contrast, individuals with XRCC1 Arg399Gln and XRCC1 Gln399Gln genotypes had significant levels of NPBs. OGG1 326 Ser/Cys, OGG1 326 Cys/Cys, XRCC1 194Arg/Thr, XRCC1 194Thr/Thr, and GSTT1 null genotypes exhibited significantly higher apoptotic values. Also, XRCC1 194Arg/Trp, XRCC1 194Thr/Thr, and GSTM1 null genotype carriers had higher necrotic levels compared to XRCC1 194Arg/Arg and GSTM1 nonnull carriers. Compositional analysis revealed the presence of iron, manganese, silicon as well as particles smaller than 2 μm that adhere to each other and form agglomerates. These results may be associated with a mixture of components, such as nitrogen dioxide, carbon monoxide, and metallic fumes, leading to significant DNA damage and cell death processes. These findings demonstrated the importance of the association between individual susceptibility and DNA damage levels due to occupational exposure to welding fumes; and constitute one of the first studies carried out in exposed workers from Colombia.

Genomic instability in peripheral blood lymphocytes of patients diagnosed with high-grade squamous intraepithelial lesions: CIN 2 versus CIN 3

Cancer is a genomic disease associated with accumulation of genetic damage. Cancer-initiating events, such as chromosome breakage, loss and rearrangement, can be used as biomarkers to evaluate individual cancer risk. Cytokinesis-block micronucleus cytome (CBMN - Cyt) assay parameters in peripheral blood lymphocytes (PBL) of thirty four patients diagnosed with high-grade squamous intraepithelial lesions (HSIL) and fifteen healthy women were measured. The genomic instability of patients diagnosed with HSIL were investigated in order to compare differences between the two subgroups of HSIL (CIN 2 and CIN 3). The micronucleus (MN) frequencies in PBL, as well as the frequencies of nucleoplasmic bridges (NPB) and nuclear buds (NBUD) were higher in patients than in controls (Mann- Whitney test, p < 0.05). These results provide evidence that CBMN cytome assay in peripheral blood lymphocytes may be used to identify individuals who are at high risk of developing cervical cancer. Since the extent of DNA damage varies between CIN 2 and CIN 3, these findings support the CIN grading system.

DNA Damage/Repair Management in Cancers

DNA damage is well recognized as a critical factor in cancer development and progression. DNA lesions create an abnormal nucleotide or nucleotide fragment, causing a break in one or both chains of the DNA strand. When DNA damage occurs, the possibility of generated mutations increases. Genomic instability is one of the most important factors that lead to cancer development. DNA repair pathways perform the essential role of correcting the DNA lesions that occur from DNA damaging agents or carcinogens, thus maintaining genomic stability. Inefficient DNA repair is a critical driving force behind cancer establishment, progression and evolution. A thorough understanding of DNA repair mechanisms in cancer will allow for better therapeutic intervention. In this review we will discuss the relationship between DNA damage/repair mechanisms and cancer, and how we can target these pathways.

An Automated, Single Cell Quantitative Imaging Microscopy Approach to Assess Micronucleus Formation, Genotoxicity and Chromosome Instability

Micronuclei are small, extranuclear bodies that are distinct from the primary cell nucleus. Micronucleus formation is an aberrant event that suggests a history of genotoxic stress or chromosome mis-segregation events. Accordingly, assays evaluating micronucleus formation serve as useful tools within the fields of toxicology and oncology. Here, we describe a novel micronucleus formation assay that utilizes a high-throughput imaging platform and automated image analysis software for accurate detection and rapid quantification of micronuclei at the single cell level. We show that our image analysis parameters are capable of identifying dose-dependent increases in micronucleus formation within three distinct cell lines following treatment with two established genotoxic agents, etoposide or bleomycin. We further show that this assay detects micronuclei induced through silencing of the established chromosome instability gene, SMC1A. Thus, the micronucleus formation assay described here is a versatile and efficient alternative to more laborious cytological approaches, and greatly increases throughput, which will be particularly beneficial for large-scale chemical or genetic screens.

Increased DNA Damage, Instability and Cytokinesis Defects in Occupationally Exposed Car Painters

BACKGROUND/AIM

Car painting is considered an occupational exposure job with high risk for cancer development, due to the association with harmful chemicals and mutagens. This study aimed to profile car painters occupationally exposed and determine its association with DNA damage and genomic instability.

MATERIALS AND METHODS

We collected a questionnaire and buccal cells of 74 individuals (37 car painters and 37 non-exposed workers) paired by age, alcohol and smoking habits. The number of pyknotic cells, karyolitic cells, karyorrhetic cells, condensed chromatin, binucleated cells, basal cells, differentiated cells (DIFF), micronucleated cells and nuclear buds were evaluated using the Buccal Micronucleus Cytome Assay protocol.

RESULTS

A statistically significant increase was observed in all parameters (p<0.05) in the exposed group, but DIFF showed a statistically significant decrease (p<0.001), compared to the control group.

CONCLUSION

In association with the poor work environment and lack of personal and collective protective equipment, occupational exposure of car painters leads to high DNA damage, genomic instability and alterations in cellular kinetics.

Micronuclei and Their Association with Infertility, Pregnancy Complications, Developmental Defects, Anaemias, Inflammation, Diabetes, Chronic Kidney Disease, Obesity, Cardiovascular Disease, Neurodegenerative Diseases and Cancer

Micronuclei (MN) are a strong cytogenetic indicator of a catastrophic change in the genetic structure and stability of a cell because they originate from either chromosome breaks or whole chromosomes that have been lost from the main nucleus during cell division. The resulting genetic abnormalities can to lead to cellular malfunction, altered gene expression and impaired regenerative capacity. Furthermore, MN are increased as a consequence of genetic defects in DNA repair, deficiency in micronutrients required for DNA replication and repair and exposure to genotoxic chemicals and ultraviolet or ionising radiation. For all of these reasons, the measurement of MN has become one of the best-established methods to measure DNA damage in humans at the cytogenetic level. This chapter is a narrative review of the current evidence for the association of increased MN frequency with developmental and degenerative diseases. In addition, important knowledge gaps are identified, and recommendations for future studies required to consolidate the evidence are provided. The great majority of published studies show a significant association of increased MN in lymphocytes and/or buccal cells with infertility, pregnancy complications, developmental defects, anaemias, inflammation, diabetes, cardiovascular disease, kidney disease, neurodegenerative diseases and cancer. However, the strongest evidence is from prospective studies showing that MN frequency in lymphocytes predicts cancer risk and cardiovascular disease mortality.

The frequencies of micronuclei, nucleoplasmic bridges and nuclear buds as biomarkers of genomic instability in patients with urothelial cell carcinoma

Bladder urothelial cell carcinoma (UCC) is an increasingly prevalent cancer worldwide, and thus, gaining a better understanding of its identifiable risk factors is a global priority. This study addressed this public health need with the understanding that cancer-initiating events, such as chromosome breakage, loss and rearrangement, can be reasonably used as biomarkers to evaluate an individual’s cancer risk. Overall, forty bladder cancer patients and twenty controls were evaluated for genomic instability. To the best of the investigators’ knowledge, this is the first study to perform micronucleus (MN) assays simultaneously in urothelial exfoliated cells (UEC), buccal exfoliated cells (BEC), and peripheral blood lymphocytes (PBL) in first-diagnosed, non-smoker bladder UCC patients. Additionally, the frequency of nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in PBL was evaluated. The MN frequencies in UEC, BEC, and PBL, as well as the frequencies of NPBs and NBUDs, were significantly higher in patients than in controls. In conclusion, MN assays, particularly in UEC, may be used to identify individuals who are at high risk of developing UCC, as single or as additional triage test to UroVysion FISH test. Our results further validate the efficacy of biomarkers, such as MN, NPBs, and NBUDs, as predictors of genomic instability.

The molecular origins and pathophysiological consequences of micronuclei: New insights into an age-old problem

Micronuclei (MN), the small nucleus-like bodies separated from the primary nucleus, can exist in cells with numerical and/or structural chromosomal aberrations in apparently normal tissues and more so in tumors in humans. While MN have been observed for over 100 years, they were merely and constantly considered as passive indicators of chromosome instability (CIN) for a long time. Relatively little is known about the molecular origins and biological consequences of MN. Rapid technological advances are helping to close these gaps. Very recent studies provide exciting evidence that MN act as key platform for chromothripsis and a trigger of innate immune response, suggesting that MN could affect cellular functions by both genetic and nongenetic means. These previously unappreciated findings have reawakened widespread interests in MN. In this review, the diverse mechanisms leading to MN generation and the complex fate profiles of MN are discussed, together with the evidence for their contribution to CIN, inflammation, senescence and cell death. Moreover, we put this knowledge together into a speculative perspective on how MN may be responsible for cancer development and how their presence may influence the choice of treatment. We suggest that the heterogeneous responses to MN may function physiological to ensure the arrestment, elimination and immune clearance of damaged cells, but pathologically, may enable the survival and oncogenic transformation of cells bearing CIN. These insights not only underscore the complexity of MN biology, but also raise a host of new questions and provide fertile ground for future research.