Micronuclei in cervical smears and peripheral blood lymphocytes from women with and without cervical uterine cancer

DBD-FISH Using Specific Chromosomal Region Probes for the Study of Cervical Carcinoma Progression

Genomic instability is an important biomarker in the progression of cervical carcinoma. DBD-FISH (DNA breakage detection-fluorescence in situ hybridization) is a sensitive method that detects strand breaks, alkali-labile sites, and incomplete DNA excision repair in cells of the cervical epithelium. This technique integrates the microgel immersion of cells from a vaginal lesion scraping and the DNA unwinding treatment with the capacity of FISH integrated into digital image analysis. Cells captured within an agarose matrix are lysed and submerged in an alkaline unwinding solution that generates single-stranded DNA motifs at the ends of internal DNA strand breaks. After neutralization, the microgel is dehydrated and the cells are incubated with DNA-labeled probes. The quantity of a hybridized probe at a target sequence corresponds to the measure of the single-stranded DNA produced during the unwinding step, which is equivalent to the degree of local DNA breakage. DNA damage does not show uniformly throughout the entire DNA of a cell; rather, it is confined to specific chromosomal sites. In this chapter, an overview of the technique is supplied, focusing on its ability for assessing the association between DNA damage in specific sequences and in the progressive stages of cervical carcinoma.

Cervical fluid pH, electrolytes and osmolarity changes and expression of ion transporters (ENaC, CFTR and AQP) in cervix of women with primary unexplained infertility

BACKGROUND

Unexplained infertility could arise from a defect in the cervix. However, the contribution of abnormal cervical fluid microenvironment to this problem still needs to be identified. Therefore, this study identifies the changes in the cervical fluid microenvironment, i.e., pH, electrolytes and osmolarity as well as expression of ion transporters in the cervix including ENaC, CFTR and AQP in fertile women and in women suffering from primary unexplained infertility.

METHODS

Fertile women and women with unexplained infertility but having regular 28-day menstrual cycles were chosen in this study, Day-22 serum progesterone levels were determined. In the meantime, serum FSH and LH levels were determined on day 2 while, cervical flushing was performed at day 14 to analyse changes in the cervical fluid pH, osmolarity, Na+ and Cl- levels. Meanwhile, cells retrieved from cervical fluid were subjected to mRNA expression and protein distribution analysis for CFTR, AQP and ENaC by qPCR and immunofluorescence, respectively.

RESULTS

No significant changes in serum progesterone, FSH and LH levels were observed between the two groups. However, cervical fluid pH, osmolarity, Na+ and Cl- levels were significantly lower in primary unexplained infertile group when compared to fertile group. Expression of CFTR and AQP (AQP 1, AQP 2, AQP 5 and AQP 7) in endocervical cells was lower and expression of β-ENaC was higher in primary unexplained infertile women (p < 0.05 when compared to fertile group).

CONCLUSIONS

Alterations in the cervical fluid microenvironment linked to the defective ion transporter expression in the cervix might contribute towards the unfavourable condition that accounts for unexplained infertility in women.

Quick assessment of DNA damage in cervical epithelial cells using a chromatin dispersion test

PURPOSE

This study was aimed to quantify genomic DNA breakages in the cervical epithelium cells of patients diagnosed with different grades of cervical lesions using a quick test based on chromatin dispersion after controlled protein depletion. The association between the progressive stages of cervical dysplasia and the levels of DNA damage, taking into account the presence of papillomavirus human (HPV) infection, was investigated.

METHODS

A hospital-based unmatched case-control study was conducted during 2018 with a sample of 78 women grouped according to histological diagnosis as follows: 23 women with low grade-squamous intraepithelial lesion (LG-SIL), 34 women with high grade- squamous intraepithelial lesion (HG-SIL), and three women with cervical carcinoma (CC). In parallel, 15 women without cervical lesions were included as a Control cohort. DNA damage levels in cervical epithelial cells were assessed using the chromatin dispersion test (CDT) and controlled in parallel with DNA breakage detection coupled with florescent in situ hybridization (DBD‒FISH) using whole genomic DNA probes.

RESULTS

CDT produces different morphotypes in the cervical epithelium that can be associated with the level of DNA breakage revealed with DBD‒FISH. A significant increase of DNA damage was correlated with the histological progression of the patients and human papillomavirus (HPV) infection.

CONCLUSION

The CDT is a simple, accurate and inexpensive morphological bioassay to identify different levels DNA damage that can be associated with the level of abnormal cells present in the cervical epithelium in patients who commonly present HPV infection.

Impact of infections, preneoplasia and cancer on micronucleus formation in urothelial and cervical cells: A systematic review

Approximately 165,000 and 311,000 individuals die annually from urothelial (UC) and cervical (CC) cancer. The therapeutic success of these cancers depends strongly on their early detection and could be improved by use of additional diagnostic tools. We evaluated the current knowledge of the use of micronucleus (MN) assays (which detect structural and numerical chromosomal aberrations) with urine- (UDC) and cervix-derived (CDC) cells for the identification of humans with increased risks and for the diagnosis of UC and CC. Several findings indicate that MN rates in UDC are higher in individuals with inflammation and schistosomiasis that are associated with increased prevalence of UC; furthermore, higher MN rates were also found in CDC in women with HPV, Candidiasis and Trichomonas infections which increase the risks for CC. Only few studies were published on MN rates in UDS in patients with UC, two concern the detection of recurrent bladder tumors. Strong correlations were found in individuals with abnormal CC cells that are scored in Pap tests and histopathological abnormalities. In total, 16 studies were published which concerned these topics. MN rates increased in the order: inflammation < ASC-US/ASC-H < LSIL < HSIL < CC. It is evident that MNi numbers increase with the risk to develop CC and with the degree of malignant transformation. Overall, the evaluation of the literature indicates that MNi are useful additional biomarkers for the prognosis and detection of CC and possibly also for UC. In regard to the diagnosis/surveillance of UC, further investigations are needed to draw firm conclusions, but the currently available data are promising. In general, further standardization of the assays is needed (i.e. definition of optimal cell numbers and of suitable stains as well as elucidation of the usefulness of parameters reflecting cytotoxicity and mitotic activity) before MN trials can be implemented in routine screening.

Mutagenicity monitoring in humans: Global versus specific origin of mutations

An underappreciated aspect of human mutagenicity biomonitoring is tissue specificity reflected in different assays, especially those that measure events that can only occur in developing bone marrow (BM) cells. Reviewed here are 9 currently-employed human mutagenicity biomonitoring assays. Several assays measure chromosome-level events in circulating T-lymphocytes (T-cells), i.e., traditional analyses of aberrations, translocation studies involving chromosome painting and fluorescence in situ hybridization (FISH) and determinations of micronuclei (MN). Other T-cell assays measure gene mutations. i.e., hypoxanthine-guanine phosphoriboslytransferase (HPRT) and phosphoribosylinositol glycan class A (PIGA). In addition to the T-cell assays, also reviewed are those assays that measure events in peripheral blood cells that necessarily arose in BM cells, i.e., MN in reticulocytes; glycophorin A (GPA) gene mutations in red blood cells (RBCs), and PIGA gene mutations in RBC or granulocytes. This review considers only cell culture- or cytometry-based assays to describe endpoints measured, methods, optimal sampling times, and sample summaries of typical quantitative and qualitative results. However, to achieve its intended focus on the target cells where events occur, kinetics of the cells of peripheral blood that derive at some point from precursor cells are reviewed to identify body sites and tissues where the genotoxic events originate. Kinetics indicate that in normal adults, measured events in T-cells afford global assessments of in vivo mutagenicity but are not specific for BM effects. Therefore, an agent's capacity for inducing mutations in BM cells cannot be reliably inferred from T-cell assays as the magnitude of effect in BM, if any, is unknown. By contrast, chromosome or gene level mutations measured in RBCs/reticulocytes or granulocytes must originate in BM cells, i.e. in RBC or granulocyte precursors, thereby making them specific indicators for effects in BM. Assays of mutations arising directly in BM cells may quantitatively reflect the mutagenicity of potential leukemogenic agents.

Smoking causes induction of micronuclei and other nuclear anomalies in cervical cells

INTRODUCTION

Smoking is an independent cause of cervical cancer, which is the 4th most common malignancy in women. It is currently not known if tobacco consumption causes chromosomal damage (which is a hallmark of human cancer) in cervical cells and if age and the hormonal status have an impact on tobacco induced genetic instability in the cervix.

METHODS

We conducted a study with pre- and post-menopausal women smokers and never-smokers (25/group). Smokers consumed 30 light/medium cigarettes/day and were matched with the non-smoking group. Cervical cells were analyzed for induction of micronuclei (MN) which are caused by structural/numerical chromosomal aberrations; additionally, other nuclear anomalies reflecting genomic instability and cytotoxicity were scored. Furthermore, the frequencies of basal cells were recorded which reflect the mitotic activity of the mucosa.

RESULTS

MN and other abnormalities were increased in both groups of smokers. The effects were most pronounced in postmenopausal smokers (i.e. 2-fold higher) compared to premenopausal smokers. Also the number of basal cells (indicative for cell proliferation) was clearly enhanced in older women. Tar and nicotine had no detectable impact on chromosomal damage but a clear association with pack-years was observed.

CONCLUSIONS

Smoking increased chromosomal instability, cytotoxicity and induced cell divisions in cervical mucosa cells of pre- and post-menopausal women. The effects were more pronounced in the latter group indicating a higher risk for diseases (including cancer) that are causally related to DNA damage.

Heterogeneity of Genetic Damage in Cervical Nuclei and Lymphocytes in Women with Different Levels of Dysplasia and Cancer-Associated Risk Factors

The comet assay can be used to assess genetic damage, but heterogeneity in the length of the tails is frequently observed. The aims of this study were to evaluate genetic damage and heterogeneity in the cervical nuclei and lymphocytes from patients with different levels of dysplasia and to determine the risk factors associated with the development of cervical cancer. The study included 97 females who presented with different levels of dysplasia. A comet assay was performed in peripheral blood lymphocytes and cervical epithelial cells. Significant genetic damage (P ≤ 0.05) was observed only in patients diagnosed with nuclei cervical from dysplasia III (NCDIII) and lymphocytes from dysplasia I (LDI). However, the standard deviations of the tail lengths in the cervical nuclei and lymphocytes from patients with dysplasia I were significantly different (P ≤ 0.0001) from the standard deviations of the tail lengths in the nuclei cervical and lymphocytes from patients with DII and DIII (NCDII, NCDIII and LDII, LDIII), indicating a high heterogeneity in tail length. Results suggest that genetic damage could be widely present but only manifested as increased tail length in certain cell populations. This heterogeneity could obscure the statistical significance of the genetic damage.

Association between cervical lesion grade and micronucleus frequency in the Papanicolaou test

The aim of this study was to evaluate the association between the frequency of micronuclei (MN) and the cellular changes detected in the conventional Papanicolaou test. One hundred and seventy-four Papanicolaou test smears with cellular changes were examined. MN screening was done in cytopathological smears by counting 1,000 cervical cells in a light microscope. MN frequencies were significantly higher in the group with cellular changes compared to the control group (p < 0.001). The mean MN frequencies were 0.95 ± 1.12 (mean ± SD) in the control group (n = 223), 2.98 ± 1.20 in individuals with atypical squamous cells of undetermined significance (ASC-US) (n = 50), 4.04 ± 1.45 in cervical intraepithelial neoplasia (CIN) I (n = 52), 5.97 ± 1.83 in CIN II (n = 30), 7.29 ± 1.55 in CIN III (n = 17) and 8.64 ± 1.55 in invasive cancer (n = 25). These findings suggest that MN monitoring should be included as an additional criterion for the early detection of cytogenetic damage in routine examinations. This monitoring should be done in the same smear as used for cytopathological examination. More specific and systematic studies are necessary to confirm this proposal.

Association between human papillomavirus (HPV) DNA and micronuclei in normal cervical cytology

The aim of the present study was to investigate the association between HPV-DNA and micronucleus (MN) frequency in women with normal cervical cytology. A total of 158 normal cervical smears were analyzed cytologically. The HPV genome was amplified using the GP5+/bioGP6+ consensus primers. HPV-DNA of high-risk types 16, 18, 31, 33, 39, 45 and 59 were also investigated. Of the 158 samples, 20 (12.7%) and 47 (29.7%) were positive for HPV-DNA and MN, respectively. Evidence for MN was found in 11 out of 20 (55%) HPV-DNA positive samples and in 36 out of 138 (26.1%) HPV-DNA negative ones. MN presence was significantly higher in HPV-DNA positive samples (p = 0.016). On the other hand, the absence of MN observed in a considerable number of HPV-DNA negative samples (102) may be of great value in predicting the absence of HPV. The mean age of HPV-DNA positive women (34.2 ± 12.6) was significantly lower than the mean age of HPV-DNA negative women (43.9 ± 13.7) (p = 0.003). Infection by one or multiple HPV types was found in 11 out of 20 (55.0%) and 9 out of 20 (45.0%) samples, respectively. The evaluation of MN using cervical smears collected for cytology tests could, thus, be used as additional information to monitor a population’s exposure to HPV.

5-bp Classical Satellite DNA Loci from Chromosome-1 Instability in Cervical Neoplasia Detected by DNA Breakage Detection/Fluorescence in Situ Hybridization (DBD-FISH)

We aimed to evaluate the association between the progressive stages of cervical neoplasia and DNA damage in 5-bp classical satellite DNA sequences from chromosome-1 in cervical epithelium and in peripheral blood lymphocytes using DNA breakage detection/fluorescence in situ hybridization (DBD-FISH). A hospital-based unmatched case-control study was conducted in 2011 with a sample of 30 women grouped according to disease stage and selected according to histological diagnosis; 10 with low-grade squamous intraepithelial lesions (LG-SIL), 10 with high-grade SIL (HG-SIL), and 10 with no cervical lesions, from the Unidad Medica de Alta Especialidad of The Mexican Social Security Institute, IMSS, Mexico. Specific chromosome damage levels in 5-bp classical satellite DNA sequences from chromosome-1 were evaluated in cervical epithelium and peripheral blood lymphocytes using the DBD-FISH technique. Whole-genome DNA hybridization was used as a reference for the level of damage. Results of Kruskal-Wallis test showed a significant increase according to neoplastic development in both tissues. The instability of 5-bp classical satellite DNA sequences from chromosome-1 was evidenced using chromosome-orientation FISH. In conclusion, we suggest that the progression to malignant transformation involves an increase in the instability of 5-bp classical satellite DNA sequences from chromosome-1.

Significance of micronucleus in cervical intraepithelial lesions and carcinoma

Background:

The micronuclei (MNi) test on exfoliated cells has been successfully used to screen population groups at risk for cancers of oral cavity, urinary bladder, cervix and esophagus. Their frequency appears to increase in carcinogen-exposed tissues long before any clinical symptoms are evident. There are only limited numbers of studies on MN scoring in cervical pre-neoplastic and neoplastic conditions.

Aims:

To compare the micronucleus (MN) score in the whole spectrum of cervical lesions including normal, inflammatory, abnormal squamous cells of undetermined significance (ASC-US), abnormal squamous cells cannot exclude HSIL (ASC-H), low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL) and invasive cancer (IC) and to evaluate the role of MN as a biomarker in different pre-neoplastic and neoplastic lesions.

Materials and Methods:

A total of 221 slides, comprised of normal (32), inflammatory (32), ASC-US (31), ASC-H (31), LSIL (32), HSIL (31) and IC (32), were studied. All the cases were reviewed by two pathologists independently. Histopathological correlation was done in a few cases of ASC-US, ASC-H, HSIL and IC which were available in the department. Two observers separately and independently counted the number of micronucleated cells per 1,000 epithelial cells in oil immersion magnification and were expressed as MN score per 1,000 cells.

Results:

The mean MN scores ± SD in normal, inflammatory, ASC-US, ASC-H, LSIL, HSIL and IC cases of cervical lesions were 0.84±0.68, 1.06±0.84, 3±0.73, 4.78±1.43, 4.06±1.13, 8.03±1.64 and 10.5±2.01, respectively. MN scores of IC and HSIL were significantly high compared to normal (P<0.000), inflammatory (P<0.000), ASC-US (P<0.000), ASC-H (P<0.000) and LSIL (P<0.000) group (analysis of variance test). LSIL showed significant difference with the normal (P<0.000), inflammatory (P=0.001), ASC-US (P=0.028), HSIL (P<0.000) and IC (<0.000), but not with the ASC-H (P=0.64) group.

Conclusions:

MN scoring on the epithelial cells of cervix could be used as a biomarker in cancer screening. This is an easy, simple, reliable, reproducible and objective test which can be performed on routinely stained pap smears.

Evaluation of DNA single and double strand breaks in women with cervical neoplasia based on alkaline and neutral comet assay techniques

A hospital-based unmatched case-control study was performed in order to determine the relation of DNA single (ssb) and double (dsb) strand breaks in women with and without cervical neoplasia. Cervical epithelial cells of 30 women: 10 with low grade squamous intraepithelial lesions (LG-SIL), 10 with high-grade SIL (HG-SIL), and 10 without cervical lesions were evaluated using alkaline and neutral comet assays. A significant increase in global DNA damage (ssb + dsb) and dsb was observed in patients with HG-SIL (48.90 ± 12.87 and 23.50 ± 13.91), patients with LG-SIL (33.60 ± 14.96 and 11.20 ± 5.71), and controls (21.70 ± 11.87 and 5.30 ± 5.38; resp.). Pearson correlation coefficient reveled a strong relation between the levels ssb and dsb (r² = 0.99, P = 0.03, and r² = 0.94, P = 0.16, resp.) and progression of neoplasia. The increase of dsb damage in patients with HG-SIL was confirmed by DNA breakage detection-FISH (DBD-FISH) on neutral comets. Our results argue in favor of a real genomic instability in women with cervical neoplasia, which was strengthened by our finding of a higher proportion of DNA dsb.

Chromosomal damage and apoptosis in exfoliated buccal cells from individuals with oral cancer

This study aimed to investigate cytological abnormalities indicative of chromosome damage (micronuclei) and apoptosis (karyorrhexis, pyknosis, and condensed chromatin) in exfoliated cells from the buccal mucosa of patients with oral cancer and control subjects. The sample included twenty individuals with oral cancer and forty individuals with normal buccal mucosa. Material was collected from the cheek epithelium in areas with lesions and areas without abnormalities. A minimum of one thousand cells was analyzed. Micronuclei were found significantly more frequently in cells collected from lesions than in cells from normal areas, independent of the presence/absence of cancer (P < 0.0001). They were also significantly more frequent in smokers and in mouthwash users (P < 0.0001). Apoptosis occurred significantly less frequently in individuals with oral cancer (P < 0.0001). These results show that oral cancer is associated with higher frequency of chromosomal damage and suggest that apoptosis is compromised in the buccal cells of individuals with this kind of neoplasia.

Micronuclei in peripheral blood from patients after cytostatic therapy mainly arise ex vivo from persistent damage

The micronucleus test (MNT) is a well-established assay in genotoxicity testing and human biomonitoring. The cytokinesis-block micronucleus test (CBMNT) is the preferred method for measuring MN in cultured human lymphocytes from human subjects exposed to genotoxins. It is, however, unclear to what extent mutagen exposure either leads to the formation of MN already in vivo or to the formation of MN ex vivo during cell culture as a consequence of persisting DNA damage. To address this question, we investigated peripheral blood of 22 patients who had received cytostatic therapies including drugs with clastogenic and aneugenic effects. We also performed the MNT with blood samples from 13 healthy controls without relevant mutagen exposure. The incidence of MN was studied 24, 48 and 72 h after the start of the culture in mononuclear lymphocytes in cultures without cytochalasin B and also at 72 h in binucleated lymphocytes in the standard CBMNT. The mean frequency of binuclear cells with MN in the CBMNT was clearly increased in blood samples from patients (29.3 versus 10.2 per 1000 in controls). In contrast, mononuclear lymphocytes analysed 24 or 48 h after start of the cultures only revealed a marginal increase in MN frequencies in comparison to controls. These results suggest that mutagen exposure in vivo mainly leads to the formation of MN during ex vivo proliferation of lymphocytes as a consequence of persistent damage. Characterization of MN in binuclear lymphocytes from patients by fluorescence in situ hybridization (FISH) with a pan-centromeric probe indicated that MN arose by clastogenic and aneugenic mechanisms. A high portion of MN was relatively large and exhibited several centromere signals. If the results of this study with patients exposed to cytostatic drugs also apply to other kinds of mutagen exposure, increased MN frequencies in the CBMNT can only be expected for exposures leading to persistent damage in peripheral lymphocytes and MN formation during ex vivo lymphocyte culture.

Prevalence of micronuclei in exfoliated uterine cervical cells from patients with risk factors for cervical cancer

CONTEXT AND OBJECTIVE

Pap smears are the most common and inexpensive screening method for cervical cancer. We analyzed micronucleus prevalence in exfoliated cervical mucosa cells, to investigate associations between increased numbers of micronuclei and risk factors for cervical cancer.

DESIGN AND SETTING

Analytical cross-sectional study, at Instituto de Pesquisa em Oncologia (IPON).

METHODS

Exfoliated cervical cells were obtained from 101 patients between September 2004 and November 2005. Patients' ages, habits (passive or active smoking, alcoholism and numbers of sexual partners), age at first sexual intercourse, contraceptive methods used, histories of sexually transmitted diseases, use of hormone replacement therapy, numbers of pregnancies and abortions, inflammatory cytology and cervical intraepithelial neoplasia (CIN) were obtained. Cells were collected using Ayre spatulas, transferred to vials containing 0.9% saline solution for micronucleus tests and analyzed at 1000x magnification. The number of micronuclei in 1,000 epithelial cells per patient sample was counted.

RESULTS

Comparisons between groups with active (7.9 +/- 7.8) and passive (7.2 +/- 10.6) smoking versus no smoking (3.7 +/- 5.1); with/without alcoholism (7.8 +/- 1.4 and 6.9 +/- 10.1); with/without inflammatory cytology (10.7 +/- 10.5 and 1.3 +/- 1.7); and with CIN I, II and III and no CIN (respectively 4.3 +/- 4.3, 10.6 +/- 5.3, 22.7 +/- 11.9 and 1.3 +/- 1.4) found elevated micronucleus prevalence (P < 0.05).

CONCLUSIONS

We concluded that the prevalence of micronuclei in exfoliated uterine cervical cells was greater in patients with one or more risk factors for uterine cervical cancer than in patients without risk factors.

Validation of micronuclei frequency in peripheral blood lymphocytes as early cancer risk biomarker in a nested case-control study

Aim of this work was to assess the predictive value of micronuclei (MN) frequency in peripheral blood lymphocytes (PBL) for the risk of cancer death in disease-free individuals. Blood samples from 1650 subjects selected from the general population of Pisa, Italy, were collected between June 1991 and November 1993. The follow-up until January 2005 recorded a total of 111 deaths (52 for cancer). MN frequency was assessed for 49 cancer cases and 101 matched controls. A significantly higher MN frequency was found in cancer cases (4.7+/-3.4 MN/1000 BN cells) versus controls (1.5+/-1.7; p<0.0001). Donors were stratified in two classes and multivariate logistic regression analysis confirmed that individuals with high MN frequency (>2.5 MN/1000 BN cells) had a significantly increased risk of cancer death (OR=10.7; 95% CI=4.6-24.9; p<0.0001) when compared to individuals with low MN frequency (<or=2.5 MN/1000 BN cells). Ageing was associated with a 6% increased risk per year (p=0.03). No influence of other potential confounders (gender, occupation, smoking and drinking habits) was observed. Finally, subjects with a higher MN frequency showed a higher MR for CVD (Logrank test, p=0.001). These findings provide strong evidence that MN frequency assessed in PBL of disease-free subjects is a good predictor of cancer death risk, evaluated by a nested case-control study performed 14 years after the original recruitment.

Lower red blood cell folate enhances the HPV-16-associated risk of cervical intraepithelial neoplasia

OBJECTIVE

We previously reported that higher circulating concentrations of folate are independently associated with a lower likelihood of becoming positive for high-risk human papillomaviruses (HR-HPVs) and of having a persistent HR-HPV infection and a greater likelihood of becoming HR-HPV negative (Cancer Res 2004;64:8788-93). In the present study conducted in the same study population, we tested whether circulating folate concentrations modify the risk of cervical intraepithelial neoplasia (CIN) > or =2 associated with specific types of HR-HPV.

METHODS

Multiple logistic regression models were used to assess associations (odds ratio with 95% confidence intervals) across HR-HPV, folate, and rigorously reviewed cervical histology of each subject.

RESULTS

HPV-16-positive women with low red blood cell folate were significantly more likely to be diagnosed with CIN > or =2 than were HPV-16-negative women with higher red blood cell folate (odds ratio 9, 95% confidence interval 3.3-24.8).

CONCLUSION

To our knowledge, this is the first study reporting an independent association of folate with risk of having CIN > or =2 in a population tested extensively for HR-HPV and CIN that also adequately controlled for several other micronutrients and known risk factors for CIN. Our findings suggest that improving the folate status in HR-HPV-infected women may reduce the risk of CIN and thus the risk of cervical cancer. Folate supplementation should be tested as a means of reducing the risk of developing CIN > or =2 in women exposed to HR-HPV, especially HPV-16.

Effects of dietary boron on cervical cytopathology and on micronucleus frequency in exfoliated buccal cells

Recent evidence indicates that boron and borates may have anticarcinogenic properties. In this study, we have investigated the incidence of adverse cytological findings in cervical smears and the micronucleus (MN) frequency in women living in boron-rich and boron-poor regions. Cervical smears were prepared from 1059 women with low socioeconomic status; 472 of the women lived in relatively boron-rich rural areas, while 587 lived in relatively boron-poor regions. The average and standard deviation values for the age of the women screened with the cervical Pap smear test were 41.55 +/- 8.38. The mean dietary intake of boron was 8.41 mg/day for women from the boron-rich regions, and 1.26 mg/day for women living in the boron-poor regions (P < 0.0001). Women from the boron-rich regions had no cytopathological indications of cervical cancer, while there were cytopathological findings for 15 women from the boron-poor areas (chi(2) = 10.473, P < 0.05). Sixty women, 30 from each region, were chosen for evaluating MN frequencies in exfoliated buccal cells. MN frequencies for women from the boron-rich and boron-poor regions were not significantly different (t = -0.294, P > 0.05). Also, there were no significant correlations between age and MN frequency for women from both the boron-rich (r = 0.133, P = 0.48, P > 0.05) and boron-poor (r = -0.033, P = 0.861, P > 0.05) regions. The results suggest that ingestion of boron in the drinking water decreases the incidence of cervical cancer-related histopathological findings. There was no correlation between the pathological findings from the cervical smears and buccal cell MN frequency suggesting that the two study populations were exposed equally to gentotoxic agents. Nonetheless, cervical cancer-related histopathological findings should be validated by other researchers.

Micronucleus induction by metronidazole in rat vaginal mucosa

Metronidazole (MTZ) is used for the treatment of many infectious diseases, including vaginal infections. While data indicate that MTZ is mutagenic and induces micronuclei in rodents, there is no information on the genotoxicity of MTZ in epithelial vaginal cells or cervical cells. In the present study, we have instilled MTZ into the vagina of rats and evaluated the micronucleus (MN) frequency in proestrus rat vaginal mucosal cells. The first identified proestrus before treatment was used to establish basal proestrus micronucleated cell (PMNC) frequencies. Rats then were assigned to one of five groups: a negative control, three MTZ treatment groups (30, 50, or 100 mg/kg MTZ), and a positive control treated with 2.5 mg of 5-fluorouracil (5-Fu) per rat. Following treatment for five consecutive days, vaginal cell samples were taken daily until three cycles of estrus were completed. Smears prepared from the samples were evaluated for micronuclei in proestrus cells. No differences were found between the PMNC frequencies of the negative control and the 30 and 50 mg/kg MTZ groups. The group treated with 100 mg/kg MTZ, however, had significantly elevated PMNC frequencies in the first and second proestrus samples, while 5-Fu treatment produced significant increases in PMNC frequency in the second and third proestrus. These results indicate that topical administration of relatively high concentrations of MTZ is genotoxic in rat vaginal mucosa cells.

Tetraploidy and chromosomal instability are early events during cervical carcinogenesis

Chromosomal instability as manifested by increases in aneuploidy and structural chromosome aberrations is believed to play a critical role in the intermediate to late stages in the development of cervical malignancies. The current study was designed to determine the role of tetraploidy in the formation of aneuploidy and ascertain the occurrence of these alterations during the earlier stages of cervical carcinogenesis. Cervical cell samples, with diagnoses ranging from Normal to high-grade lesions, (HSIL) were obtained from 143 women and were evaluated for chromosomal alterations using dual-probe fluorescence in situ hybridization. Cervical cells from a subset of the group were also evaluated for chromosomal instability in the form of micronuclei. The frequencies of cells exhibiting either tetrasomy or aneusomy for Chromosomes 3 and 17 increased significantly with disease progression and displayed distinctive patterns where aneusomy was rarely present in the absence of tetrasomy. The frequencies of micronuclei that formed through either chromosomal loss or breakage increased significantly in both the low-grade and high-grade diagnostic categories and were highly correlated with both the number of tetrasomic and aneusomic cervical cells. In addition, a unique chromosomal alteration involving a significant non-random loss of Chromosome 17 specific to near-tetraploid aneusomic cells (trisomy 17 and tetrasomy 3) was observed. We conclude that tetraploidy and chromosomal instability are related events occurring during the early stages of cervical carcinogenesis that predispose cervical cells to the formation of aneuploidy frequently involving the loss of Chromosome 17.

Micronucleus frequency in acquired middle ear cholesteatoma

OBJECTIVE

To determine the micronucleus (MN) frequency of acquired cholesteatoma tissue using an MN assay.

MATERIAL AND METHODS

Eighteen patients were diagnosed as having chronic otitis media with acquired cholesteatoma and were divided into primary and secondary acquired cholesteatoma groups. Cholesteatoma tissue and normal tissue specimens from the external ear canal skin were taken from the patients during surgical operations. MN frequencies of cholesteatoma and control samples were determined according to standard criteria.

RESULTS

The MN frequencies of the cholesteatoma and control tissues were 0.54%+/-0.31% and 0.24%+/-0.11%, respectively (p<0.01). MN frequencies for the primary and secondary acquired cholesteatoma groups were 0.63%+/-0.36% and 0.46%+/-0.26%, respectively (p>0.05). MN frequencies in cholesteatoma patients without and with complications were 0.42%+/-0.19% and 0.85%+/-0.37%, respectively (p<0.05).

CONCLUSION

MN frequencies were found to be increased in cholesteatoma tissues when compared with external ear canal skin. The MN frequency in five cases with complications was higher than in cases without complications. These results indicate that there could be associations between MN frequency and acquired cholesteatoma and between MN frequency and complications.