Genomic instability and tumor-specific DNA alterations in oral leukoplakias

Antimelanoma Effects of Alchemilla vulgaris: A Comprehensive In Vitro and In Vivo Study

Due to the rich ethnobotanical and growing evidence-based medicine records, the Alchemillae herba, i.e., the upper parts of the Lady's mantle (Alchemilla vulgaris L.), was used for the assessment of antimelanoma activity. The ethanolic extract of A. vulgaris strongly suppressed the viability of B16F1, B16F10, 518A2, and Fem-X cell lines. In contrast to the in vitro study, where the B16F1 cells were more sensitive to the treatment than the more aggressive counterpart B16F10, the results obtained in vivo using the corresponding syngeneic murine model were quite the opposite. The higher sensitivity of B16F10 tumors in vivo may be attributed to a more complex response to the extract compared to one triggered in vitro. In addition, the strong immunosuppressive microenvironment in the B16F1 model is impaired by the treatment, as evidenced by enhanced antigen-presenting potential of dendritic cells, influx and activity of CD4+ T and CD8+ T lymphocytes, decreased presence of T regulatory lymphocytes, and attenuation of anti-inflammatory cytokine production. All these effects are supported by the absence of systemic toxicity. A. vulgaris extract treatment results in a sustained and enhanced ability to reduce melanoma growth, followed by the restoration of innate and adopted antitumor immunity without affecting the overall physiology of the host.

World Workshop on Oral Medicine VII: Prognostic biomarkers in oral leukoplakia: A systematic review of longitudinal studies

OBJECTIVE

To identify the prognostic biomarker candidates for stratification and long-term surveillance of oral leukoplakia progressing to cancer via a systematic literature review.

MATERIALS AND METHODS

Systematic searches with no date restrictions were conducted on March 29, 2018, targeting the databases PubMed (Ovid), EMBASE (Ovid), EBM (Ovid), and Web of Science (ISI). Bias was assessed using the Quality in Prognosis Studies tool. Biomarkers were stratified based on hallmarks of cancer.

RESULTS

Inclusion criteria were met by 25 of 3,415 studies. A range of biomarkers were evaluated experimentally for risk stratification, prognosis, and surveillance of oral leukoplakia in tissue, blood, and saliva. However, the studies were highly heterogeneous and require further validation. Biomarkers reported in these studies included inflammatory or oxidative markers, growth factors, ion channels, genetic and cellular regulatory factors, and epigenetic biomarkers. Studies tended to include small sample sizes, under-reported or variably reported histopathological data, did not address potential confounding, reported limited/variable follow-up data, or lacked a control group. Inclusion of subsets from chemoprevention trials may have introduced bias regarding reported malignant transformation rates and accuracy of prognostic biomarkers.

CONCLUSIONS

This review identified insufficient longitudinal evidence to support validated prognostic biomarkers for oral leukoplakia. Further studies are needed to identify molecular targets with the potential to mitigate risk of malignant transformation.

Oral keratosis of unknown significance shares genomic overlap with oral dysplasia

OBJECTIVES

To identify molecular characteristics of keratosis of unknown significance and to nominate pathways of molecular progression to oral cancer. Our work could provide a rationale for monitoring and treating these lesions definitively.

METHODS

Patients with oral leukoplakia were eligible for our prospective observational study. We correlated alterations in cancer-associated genes with clinical and histopathologic variables (keratosis of unknown significance vs. moderate-to-severe dysplasia) and compared these alterations to a previously molecularly characterized oral cancer population.

RESULTS

Of 20 enrolled patients, 13 (65%) had evidence of keratosis of unknown significance, while seven (35%) had dysplasia. Nine patients (45%) developed oral cancer (4/13 with keratosis of unknown significance, 5/7 with dysplasia). At a median follow-up of 67 (range 22-144) months, median overall survival was significantly shorter for patients with dysplasia (hazard ratio 0.11, p = .02). KMT2C and TP53 alterations were most frequent (75% and 35%, respectively). There were molecular similarities between keratosis of unknown significance and dysplasia patients, with no significant differences in mutational frequency among genes with ≥15% rate of alteration.

CONCLUSIONS

Among patients with leukoplakia, both patients with keratosis of unknown significance and patients with dysplasia developed oral cancer. Molecular alterations between these two groups were similar at this sample size.

Human MutL homolog 1 immunoexpression in oral leukoplakia and oral squamous cell carcinoma: A prospective study in Indian population

BACKGROUND

Mammalian mismatch repair system is responsible for maintaining genomic stability during repeated duplications, and human MutL homolog 1 (hMLH1) protein constitutes an important part of it. Various isolated studies have reported the altered expression of hMLH1 in oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC). Research is lacking in the quantitative estimation and comparison of hMLH1 expression in OL and OSCC.

AIMS

To evaluate, quantify and compare hMLH1 immunoexpression in normal oral mucosa, OL and OSCC.

SETTINGS AND DESIGN

Thirty patients of OL and thirty patients of OSCC formed the study group and thirty patients were included in the control group (normal oral mucosa). Formalin-fixed paraffin wax blocks were prepared from the tissue samples.

MATERIALS AND METHODS

Immunohistochemistry for hMLH1 was performed, and the total number of positive cells was counted in high-power fields, and based on that percentage positivity of hMLH1 was calculated in all the cases.

STATISTICAL ANALYSIS

Kruskal-Wallis and t-test were used. P < 0.05 was considered to be statistically significant.

RESULTS

The mean hMLH1 value in control group, leukoplakia and OSCC was 78.26, 54.33 and 40.97 respectively. hMLH1 immunoexpression showed decreasing indexes from control group to leukoplakia and then further to OSCC. hMLH1 expression was significantly lower in OSCC as compared to leukoplakia. There was no significant correlation of mean hMLH1 expression between different clinical and histopathological stages of leukoplakia and OSCC.

CONCLUSIONS

hMLH1 immunoexpression was inversely related to the degree of dysplasia. These findings suggest that there is a progressive decrease in hMLH1 expression from control to leukoplakia and further to OSCC. Thus, it can be concluded that hMLH1 can be used as a reliable biomarker for malignant transformation.

MutSα and MutLα immunoexpression analysis in diagnostic grading of oral epithelial dysplasia and squamous cell carcinoma

OBJECTIVES

This study explored the expression of DNA mismatch repair (MMR) proteins in a range of oral biopsies. We further evaluated the significance of MMR protein expression combined with basic demographic data in differentiating grades of oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC).

STUDY DESIGN

Immunohistochemical expression of MutSα (hMLH1 and hPMS2) and MutLα (hMSH2 and hMSH6) were compared in 98 formalin-fixed paraffin embedded oral biopsies: 21 normal, 24 mild-dysplasia (MD), 8 moderate-to-severe-dysplasia (SD), and 45 OSCC.

RESULTS

Expression of hMLH1, hPMS2, and hMSH2 was reduced in MD, SD, and OSCC compared with the normal. Reduced hMSH2 immunoreactivity discriminated poorly differentiated OSCC from well-differentiated OSCC. The diagnostic model correctly classified 71.4% of cases and revealed that hPMS2-negative biopsies were more likely to be cancerous (odds ratio [OR], 0.11; 95% confidence interval [CI], 0.000-0.813; P = .040).

CONCLUSION

The results suggested a diagnostic role for MMR proteins in OED and OSCC.

Effects of arsenic exposure on DNA methylation in cord blood samples from newborn babies and in a human lymphoblast cell line

BACKGROUND

Accumulating evidence indicates that in utero exposure to arsenic is associated with congenital defects and long-term disease consequences including cancers. Recent studies suggest that arsenic carcinogenesis results from epigenetic changes, particularly in DNA methylation. This study aimed to investigate DNA methylation changes as a result of arsenic exposure in utero and in vitro.

METHODS

For the exposure in utero study, a total of seventy-one newborns (fifty-five arsenic-exposed and sixteen unexposed newborns) were recruited. Arsenic concentrations in the drinking water were measured, and exposure in newborns was assessed by measurement of arsenic concentrations in cord blood, nails and hair by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In the in vitro study, human lymphoblasts were treated with arsenite at 0-100 μM for two, four and eight hours (short-term) and at 0, 0.5 and 1.0 μM for eight-weeks period (long-term). DNA methylation was analyzed in cord blood lymphocytes and lymphoblasts treated with arsenite in vitro. Global DNA methylation was determined as LINE-1 methylation using combined bisulfite restriction analysis (COBRA) and total 5-methyldeoxycytidine (5MedC) content which was determined by HPLC-MS/MS. Methylation of p53 was determined at the promoter region using methylation-specific restriction endonuclease digestion with MspI and HpaII.

RESULTS

Results showed that arsenic-exposed newborns had significantly higher levels of arsenic in cord blood, fingernails, toenails and hair than those of the unexposed subjects and a slight increase in promoter methylation of p53 in cord blood lymphocytes which significantly correlated with arsenic accumulation in nails (p < 0.05) was observed, while LINE-1 methylation was unchanged. Short-term in vitro arsenite treatment in lymphoblastoid cells clearly demonstrated a significant global hypomethylation, determined as reduction in LINE-1 methylation and total 5-MedC content, and p53 hypermethylation (p < 0.05). However, a slight LINE-1 hypomethylation and transient p53 promoter hypermethylation were observed following long-term in vitro treatment.

CONCLUSIONS

This study provides an important finding that in utero arsenic exposure affects DNA methylation, particularly at the p53 promoter region, which may be linked to the mechanism of arsenic carcinogenesis and the observed increased incidence of cancer later in life.

hMLH1 immunoexpression is related to the degree of epithelial dysplasia in oral leukoplakia

BACKGROUND

hMLH1 is a protein of the mammalian mismatch repair system responsible for genomic stability during repeated duplication. Relation between its altered expression linked to microsatellite instability has also been observed in oral leukoplakias (OL) and squamous cell carcinomas pointing to a possible role of hMLH1 in oral carcinogenesis. To our knowledge, this is the first study evaluating the immunoexpression of hMLH1 in OLs regarding their different degrees of epithelial dysplasia.

METHODS

Sixty-two specimens of OL were classified in four groups: 17 without dysplasia, 19 with mild dysplasia, 16 with moderate dysplasia, and 10 with severe dysplasia. Immunohistochemistry for hMLH1 was performed, and percentage of positive cells was assessed. In the statistical analysis, P values <0.005 were considered significant.

RESULTS

hMLH1 immunoexpression showed decreasing indexes from lesions with lower degrees of dysplasia to lesions with more severe dysplasia. Statistical difference was found mainly between suprabasal layers and total indexes.

CONCLUSIONS

hMLH1 immunoexpression was inversely related to the OL degree of dysplasia. The total epithelial hMLH1 index seems to be of more clinical relevance than the evaluation stratified by layers. Our findings also suggest a role of such alterations in this pathway of DNA repair as an early event in oral carcinogenesis.