State of art of micronuclei assay in exfoliative cytology as a clinical biomarker of genetic damage in oral carcinogenesis: A systematic review and meta-analysis

Oral squamous cell carcinoma (OSCC) is the most common oral malignancy, often preceded by oral potentially malignant disorders (OPMDs). Currently, no clinical biomarker exists to predict malignancy, necessitating OPMD follow-up. Habits and environmental factors, such as smoking, and alcohol consumption, influence OSCC onset. Increased micronuclei (MNs) formation has been observed in the development of OSCC. Non-invasive diagnostic tests like exfoliative cytology offer painless and regular monitoring options. This study evaluates the impact of tobacco, alcohol, and pesticide exposure on MNs occurrence in exfoliative cytology-collected oral mucosal cells, assessing their potential as non-invasive biomarker for OSCC development prediction and monitoring in high-risk patients. Despite results from this meta-analysis supporting the existence of a stepwise increase from controls to patients with OPMD to OSCC, the translation of these findings into clinical practice is limited due to intra- and inter-individual heterogeneity, as well as methodological variability in MNs quantification. Various factors contribute to this heterogeneity, including demographic variables, methodological variability of different laboratories, staining techniques, sample collection location, and patient characteristics. All these points were discussed to provide further insights and improve standardization for future studies.

Evaluation of micronuclei, cytomorphometric and cytologic changes of the oral mucosa in hookah and cigarette smokers

OBJECTIVE

To analyze the effect of hookah and cigarettes on the oral mucosa of smokers through the use of exfoliative cytology.

STUDY DESIGN

Smear samples were collected by exfoliative cytology from the tongue of 33 hookah smokers, 22 cigarette smokers, and 30 non-smokers. The selected analyses include micronuclei (MN), metanuclear anomalies, epithelial maturation, and cytomorphology (nuclear area [NA], cytoplasmic area [CA], and NA/CA ratio).

RESULTS

The largest differences observed for MN and metanuclear anomalies were between cigarette smokers and the control group (notably 1 MN P = .04; total cells with MN P = .039; total MN P = .042; karyorrhexis and binucleation, P = .0001). The hookah group, compared with the control group, showed the greatest differences for karyolysis (P = .0023), binucleation (P = .0003), and broken egg (P = .008). Significant differences were found between the smokers and the control groups regarding changes in the superficial cell without nucleus, perinuclear halo, vacuolization, color change, mucus, and keratohyalin granules. There was a significant increase in the NA and NA/CA ratio in the smoker groups.

CONCLUSION

This study showed that a combined analysis of exfoliative cytology associated with other diagnostic methods is a useful tool for studying oral carcinogenesis. Hookah and cigarettes showed similar effects in terms of displaying substantial cytogenetic and cytotoxic damage.

Amelioration of Cytogenotoxic Damage in Drug Abusers Supplemented with Folic Acid

BACKGROUND

Cytogenotoxic damage caused by the consumption of legal and illegal drugs in drug abusers has been demonstrated, primarily due to alterations in their antioxidant capacity, cellular repair mechanisms, and increased production of free radicals. Folic acid shows antioxidant activity by acting as a reducing agent, neutralizing present free radicals, and reducing genomic damage.

METHODS

The intervention involved administering 15 mg of folic acid, divided into three doses per day, to a group of 44 drug abusers. The frequency of nuclear abnormalities (NAs) was determined; micronuclei (MNs), nuclear buds (NBUDs), binucleated cells (BNs), abnormally condensed chromatin (CC), karyorrhexis (KX), pyknotic nuclei (PNs), and karyolysis (KL) were determined at different pre-treatment (baseline) and post-treatment time points at 15 and 30 days. Additionally, a group of 44 healthy individuals was used as the control group.

RESULTS

We observed a statistically significant decrease in the frequency of NAs in the drug abuser group (28.45 ± 17.74 before supplementation vs. 11.18 ± 7.42 at 15 days and 9.11 ± 10.9 at 30 days of supplementation). Specifically, it decreased the frequency of NBUDs, BNs, CC, KX, and PNs (p < 0.05).

CONCLUSION

Our study demonstrates a clear improvement in cytogenotoxic damage in drug abusers supplemented with folic acid.

Cytogenotoxicity effects in addicts with multidrug consumption

Drug abuse is considered a global health problem with serious social impact. In recent decades, changes in drug consumption patterns have shown a clear rising trend in the use of multiple drugs. Although the buccal micronucleus cytome (BMCyt) assay has evaluated cytotoxicity in drug abuse, there has not been an approach that takes into account this pattern of multiple drug use. Therefore, in this study, we evaluate for the first time the cytogenotoxic effects in multidrug users, and its correlation with the amount consumed and years of abuse. This study was conducted on 166 individuals by the BMCyt assay. A total of 83 individuals with a history of multiple licit (alcohol and tobacco) and at least one illicit drug abuse (marijuana, methamphetamines, cocaine, and/or inhalants), and 83 healthy individuals, non-drug abusers were analyzed. The results showed that drug abusers had higher frequencies of nuclear abnormalities nuclear buds, binucleated cells, pyknotic nuclei (PNs), karyorrhexis (KX), and abnormally condensed chromatin when compared with healthy controls. Moreover, results suggests that the use of licit and illicit drugs is related to cytogenotoxic damage, as was shown by an upward trend in the frequency of nuclear abnormalities identified in groups 1 (alcohol + tobacco + at least one illicit drug) and 2 (tobacco + at least one illicit drug). Furthermore, a positive correlation was found in the different groups, between the years and the amount of consumption of some drugs (alcohol, methamphetamine, and tobacco) with cytotoxicity markers such as KL, KX, and PNs.

Preliminary Findings on the Salivary Metabolome of Hookah and Cigarette Smokers

The aim of the study was to evaluate the salivary metabolomic profile of patients who habitually smoke hookah and cigarettes. The groups consisted of 33 regular and exclusive hookah smokers, 26 regular and exclusive cigarette smokers, and 30 nonsmokers. Unstimulated whole saliva was collected for the measurement of salivary metabolites by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The MetaboAnalyst software was used for statistical analysis and evaluation of biomarkers. 11 smoking salivary biomarkers were identified using the area under receiving-operator curver criterion and threshold of 0.9. Xylitol and octadecanol were higher in cigarette smokers compared to controls; arabitol and maltose were higher in controls compared to cigarette smokers; octadecanol and tyramine were higher in hookah smokers compared to controls; phenylalanine was higher in controls compared to hookah smokers; and fructose, isocitric acid, glucuronic acid, tryptamine, maltose, tyramine, and 3-hydroxyisolvaleric acid were higher in hookah smokers compared to cigarettes smokers. Conclusions: The evaluation of the salivary metabolome of hookah smokers, showing separation between the groups, especially between the control versus hookah groups and cigarette versus hookah groups, and it seems to demonstrate that the use of hookah tobacco is more damaging to health.

Association between DNA ploidy and micronucleus frequency in chronic smokers and impact of smoking cessation

Tobacco use may initiate the process of oral carcinogenesis with clinically undetectable changes. Smoking cessation may prevent its progression. The objective of this study was to evaluate the association between DNA ploidy and micronucleus (MN) frequency in chronic smokers. Three groups were evaluated: Smoker Group, Former Smoker Group and Control Group. Exfoliative cytology was performed on the lateral border of the tongue and mouth floor. MN and DNA ploidy analyses were performed, as well as the correlation between the variables. The data showed a difference between the groups for the total MN (p = 0.0227), and the Smoker group had the highest mean (4.22 ± 4.12). The three groups did not differ statistically from each other on ploidy evaluation (p-value > 0.05). There was also an association between aneuploidy and increased MN frequency in the Former Smoker group (p = 0.0036). In conclusion, these results point out that there is a relationship between the frequency of MN and aneuploidy in former smokers. Moreover, smoking cessation, even for a short period of time, may promote the decrease of MN frequency caused by tobacco use.

Effect of High-Dose Topical Minoxidil on Erythrocyte Quality in SKH1 Hairless Mice

Simple Summary

In any animal species, involuntary exposure to unknown agents may increase genetic material damage. This genetic damage can also induce the appearance of diseases such as cancer or other pathologies, including problems that can be passed on to the offspring of the damaged individual. For instance, living organisms may be affected due to the use of medications or exposure to certain chemical, physical, or biological agents which cause cell failure. This impaired function acts as an indicator that helps identify and evaluate damage in order to avoid or minimize it. In this work, excessive doses of a cosmetic drug for topical use in dermatological treatments, known as minoxidil, produced defects in the blood of hairless mice, particularly in red cells, indicating loss of DNA, a situation that may compromise life or the offspring by causing damage to their genetic material. It is important to consider that compounds may be tissue- or species-specific, although we cannot rule out the possibility that similar damage could occur in other animal species. Thus, excessive exposure to this compound should be prevented.

Abstract

SKH1 hairless mice are widely used in carcinogenesis and dermatology research due to their bare skin, as exposure to different agents is facilitated. Minoxidil is a cosmetic drug that is recognized as a mitogenic agent, and mitogens are suggested to have carcinogenic and mutagenic potential by inducing cell division and increasing the possibility of perpetuating DNA damage. Therefore, we hypothesized that the application of high doses of minoxidil to the skin of hairless mice would increase the number of micronucleated erythrocytes (MNEs) in peripheral blood. The objective of this study was to evaluate the topical administration of high doses of minoxidil on peripheral blood erythrocytes of SKH1 mice by means of micronucleus assay. Minoxidil was administered on the entire body surface of mice every 12 or 24 h. Minoxidil dosing every 24 h increased the number of micronucleated polychromatic erythrocytes (MNPCEs), and dosing every 12 h increased the number of MNEs and MNPCEs, as compared to baseline and the negative control group. No decrease in polychromatic erythrocyte frequencies was observed in the minoxidil groups. Therefore, topical application of high minoxidil doses to mice can produce DNA damage, as observed through an increase in the number of MNEs, without producing cytotoxicity, possibly due to its mitogenic effect.

Effects of age, sex, medication, and environmental conditions on genetic alterations in oral mucosa cells

In the present study, we evaluated the effects of biological factors, lifestyle factors, and environmental conditions on the induction of DNA damage in exfoliated cells of the oral mucosa. Age, sex, medication use, and environmental conditions were analyzed in individuals residing in the cities of Caarapó and Itaporã. The individuals were assessed by a questionnaire, and oral mucosa cells were collected and subjected to mutagenicity analysis. We observed no statistical differences in DNA damage related to sex. However, the mutagenic effect was found to be proportional to age, with higher frequencies of DNA damage observed in individuals between the ages of 46 and 65 years. In addition, higher frequencies of DNA damage were found in individuals who continuously used medication and for prolonged periods, and greater DNA damage was observed in individuals who used antihypertensive drugs than those who took antidepressants. In terms of environmental conditions, Caarapó residents had a significantly higher frequency of DNA damage than that of residents from Itaporã. Based on the analysis of land use and occupation, this result can be attributed to the smaller fraction of forest fragments and the higher proportion of buildings in Caarapó than Itaporã. We concluded that age, continued medication use, and environmental conditions can lead to greater DNA damage.

Buccal micronucleus cytome assay of populations under chronic heavy metal and other metal exposure along the Santiago River, Mexico

The Santiago River is one of the most contaminated rivers in Mexico, with heavy metal levels above the allowed limits. Scientific evidence indicates that chronic heavy metal exposure leads to cytogenotoxic effects. The aims of this study were to evaluate the genotoxic and cytotoxic effects of such exposure in buccal mucosa cells by micronucleus (MN) assay and to identify other nuclear abnormalities (NAs), such as nuclear buds (NBUDs), binucleated cells (BNs), pyknotic nuclei (PNs), karyorrhexis (KX), karyolysis (KL), and abnormally condensed chromatin (CC). Assays were performed on samples from four populations located alongside the Santiago River that are under chronic exposure to heavy metals and other metals (HMMs), and the results were compared with those of a population without exposure to HMMs. The exposed group showed increased frequencies of NAs (KX, CC, and KL), which are associated with cytotoxic damage, and NBUDs, which are associated with genotoxic damage. Increased frequencies of NBUDs and CC were observed in subjects from El Salto/Juanacatlán, Ocotlán, and Paso de Guadalupe, and an increase in KX frequency was observed in subjects from El Salto/Juanacatlán. Significant differences in KL frequency were observed in subjects from La Barca, El Salto/Juanacatlán, Paso de Guadalupe, and Ocotlán. Predictors for increased development of MNs and NBUDs were high concentrations of Al, Zn, and Cu. In conclusion, chronic exposure to HMMs, especially Al, Cu, and Zn, in the studied population could be related to increased frequencies of NAs, such as NBUDs, KX, CC, and KL, in the buccal mucosa cells.

Is DNA ploidy related to smoking?

BACKGROUND

In the oral cavity, genomic instability is caused by long-term exposure to carcinogens. The aim of this study was to evaluate the relationship between smoking and DNA ploidy.

METHODS

Cytological material was obtained from patients participating in the Outpatient Smoking Treatment Program of the Heart Institute (INCOR-HCFMUSP), and of the Discipline of Oral Medicine (ICT-UNESP). The inclusion criteria for all groups were the absence of a history of malignant tumors, absence of clinical signs of changes in the selected area, and alcohol consumption of less than 3 units per week. Group 1:30 smokers before smoking cessation treatment; Group 2:30 non-smokers; Group 3:30 ex-smokers abstinent for at least 1 year. Cytological smears were collected from the floor of the mouth and border of the tongue and stained by Feulgen. Aneuploidy was evaluated using the ACIS® III system.

RESULTS

The Kruskal-Wallis test showed no statistically significant difference (P = .4383) between the groups studied. No association between tobacco consumption and aneuploidy was observed in group 1 (P = 1) or group 2 (P = .68; Fisher's exact test).

CONCLUSION

Smoking was not associated with changes in DNA content or the incidence of aneuploidy in normal oral mucosa.

Cytological and cytomorphometric evaluation of the oral mucosa in HIV-infected patients undergoing antiretroviral therapy

BACKGROUND

To evaluate HIV infection-induced alterations in the oral mucosa by comparing inflammation, cell maturation, and cytomorphometric changes in oral mucosal cells between HIV-infected patients undergoing highly active antiretroviral therapy (HAART) and non-HIV-infected patients.

METHODS

Thirty HIV-infected patients undergoing HAART and 30 non-HIV-infected patients were studied. Four smears were obtained from the lateral border of the tongue and floor of the mouth with a cytobrush. One sample was stained by the Papanicolaou technique, and three samples were processed for Feulgen staining. Papanicolaou-stained smears were analyzed by light microscopy, and the cytoplasmic (CA) and nuclear (NA) area were measured with the Software AxioVision 4.7.

RESULTS

The Wilcoxon signed-rank test showed a significant difference in intermediate epithelial cell types between the HIV-infected and non-HIV-infected groups (P=.005). However, this difference was not observed for superficial epithelial cell types with (P=.672) and without a nucleus (P=.069). Comparative analysis revealed no significant difference in CA (P=.604), NA (P=.298) or NA/CA (P=.456) between the HIV-infected and non-HIV-infected groups. Keratohyalin granules were more frequent in the non-HIV-infected group (P=.0001).

CONCLUSIONS

The results showed alterations in cell maturation in HIV-infected patients undergoing HAART with undetectable viral load, but no morphometric changes were observed.

Cytopathological Changes Induced by the Crack Use in Oral Mucosa

AIMS

To evaluate cytological alterations, inflammation, and microbial charge of the oral mucosa epithelium in crack users in in terms of the amount and duration of use.

METHODS

Two hundred thirty four crack users (case group) and 120 non-users (control group) participated in this study. Clinically healthy epithelial cells were collected from the posterior mouth floor, using the conventional exfoliative cytology. Some of the aspects evaluated were as follows: Papanicolaou classification, nuclear area (NA), cytoplasmic area (CA), nuclear/cytoplasmic area ratio (NA/CA), inflammation, microbial charge, keratinization, enucleated superficial cells, and binucleation.

RESULTS

The average time of crack consumption was 9.8 years (±7.1) and the average quantity of use was 13.97 g/week (±18.5). The average NA values and NA/CA ratio were increased and CA values were decreased in the case group compared to those in the controls (p < 0.05). Papanicolaou class II, intense inflammation, and intense microbial charge were more prevalent in the case group than in the controls (p < 0.05). There was a significant association between high quantity of smoked crack rocks per week and increased CA values, absence of keratinization, and presence of enucleated superficial cells (p < 0.05).

CONCLUSION

Crack use seemed to induce inflammatory alterations and early indicators of malignant transformation on the oral mucosa epithelium.

Effect of HIV infection in the micronuclei frequency on the oral mucosa

BACKGROUND

The genotoxic impact of HIV infection on the oral cavity malignancies is unknown. The aim of this study was to evaluate the effect of HIV infection in micronucleus (MN) frequency on the oral mucosa of HIV+ patients and establish a relationship with early cytogenetic changes in oral carcinogenesis.

METHODS

Thirty HIV+ individuals who are under highly active antiretroviral therapy (HAART) and 30 non-HIV patients were evaluated. Two smears were taken from the lateral border of the tongue and mouth floor and stained by Feulgen. The frequency of MN was examined in 3000 cells per subject under common microscopy.

RESULTS

MN analysis showed no significant difference between groups by Mann-Whitney U-test for total MNs (P = 0.178). The presence of single MN was greater in control group with statistical significance (P = 0.009), while in HIV group, multiple MNs were exhibited in higher mean.

CONCLUSIONS

HIV patients under HAART therapy and low viral load values showed higher frequency of multiple MNs, which, although not statistically significant, may be caused by the action of the Vpr gene, an accessory gene of HIV. These results corroborate the theory of HIV infection cytogenetic damage.

Nuclear changes in oral mucosa of alcoholics and crack cocaine users

The effects of drugs of abuse on oral mucosa are only partly understood. The aims of the present study were to: (1) evaluate the frequency of nuclear changes in normal-appearing oral mucosa of alcoholics and crack cocaine users and (2) assess their association with cell proliferation rate. Oral smears were obtained from the border of the tongue and floor of the mouth of 26 crack cocaine users (24 males and 2 females), 29 alcoholics (17 males and 12 females), and 35 controls (17 males and 18 females). Histological slides were submitted to Feulgen staining to assess the frequency of micronuclei (MN), binucleated cells (BN), broken eggs (BE), and karyorrhexis (KR). A significant increase in the frequency of MN was observed in cells exfoliated from the tongue of crack cocaine users ( p = 0.01), and alcoholics showed a higher frequency of KR in cells obtained from the floor of the mouth ( p = 0.01). Our findings suggest that the use of crack cocaine induces clastogenic effects, whereas alcoholism is associated with higher degrees of keratinization in the floor of the mouth.

Genotoxicity in gingival cells of patients undergoing tooth restoration with two different dental composite materials

OBJECTIVES

Dental composite materials come into direct contact with oral tissue, especially gingival cells. This study was performed to evaluate possible DNA damage to gingival cells exposed to resin composite dental materials.

MATERIALS AND METHODS

Class V restorations were placed in 30 adult patients using two different composite resins. The epithelial cells of the gingival area along the composite restoration were sampled prior to and after 7, 30, and 180 days following the restoration of the tooth. DNA damage was analysed by comet and micronucleus assays in gingival exfoliated epithelial cells.

RESULTS

The results showed significantly higher comet assay parameters (tail length and % DNA in the tail) within periods of 30 and 180 days. The micronucleus test for the same exposure time demonstrated a higher number of cells with micronuclei, karyolysis, and nuclear buds. Results did not reveal any difference between the two composite materials for the same duration of exposure.

CONCLUSION

Based on the results, we can conclude that the use of composite resins causes cellular damage. As dental composite resins remain in intimate contact with oral tissue over a long period of time, further research on their possible genotoxicity is advisable.

CLINICAL RELEVANCE

Long-term exposure of gingival cells to two different composite materials demonstrated certain DNA damage. However, considering the significant decline in micronuclei frequency after 180 days and efficiency in the repair of primary DNA damage, the observed effects could not be indicated as biologically relevant.