S-phase fraction and DNA ploidy in oral leukoplakia

Prognostic Implications of DNA Repair, Ploidy and Telomerase in the Malignant Transformation Risk Assessment of Leukoplakia

BACKGROUND

Although leukoplakia shows a higher risk for malignant transformation to oral cancer, currently there are no clinically relevant biomarker which can predict the potentially high risk leukoplakia. This study aimed to investigate the genetic alterations such as DNA ploidy, telomerase expression and DNA repair capacity as predictive markers of malignant transformation risk of leukoplakia.

METHODS

The study was initiated in September 2005 and patients were followed up to March 2014. Two hundred patients with oral leukoplakia, 100 patients with oral cancer and 100 healthy, age and sex matched adults with normal oral mucosa as controls were recruited. The DNA ploidy content was measured by high resolution flow cytometry, level of telomerase expression was identified by TRAP assay and intrinsic DNA repair capacity was measured by mutagen induced chromosome sensitivity assay of cultured peripheral blood lymphocytes. The Chi-square test or Fisher's Exact test was used for comparison of categorical variables between biomarkers. A p value less than or equal to 0.05 was considered as statistically significant. Analysis was performed with SPSS software version 16. Logistic regression was used to find the association between the dependent and three independent variables.

RESULTS

There was significant difference in the distribution of ploidy status, telomerase activity and DNA repair capacity among control, leukoplakia and oral cancer group (p<0.001). When the molecular markers were compared with histological grading of leukoplakia, both DNA ploidy analysis and telomerase activity showed statistical significance (p<0.001). Both aneuploidy and telomerase positivity was found to coincide with high-risk sites of leukoplakia and were statistically significant (p.

Diagnostic Utility of Cytology in Assessment of Ploidy Status in Potentially Malignant Oral Disorders

INTRODUCTION

Oral leukoplakia, the most common potentially malignant oral disorder (PMOD) may progress to oral squamous cell carcinoma (OSCC). Although, the current standard of care for assessing its malignant potential remains histological examination and assessing the severity of dysplasia, DNA ploidy analysis has been suggested as a surrogate marker to predict the behaviour of PMODs.

OBJECTIVES

To detect aneuploidy and to correlate ploidy status with different grades of dysplasia in both tissue and cytology samples to predict the behaviour of these potentially malignant disorders and to assess the diagnostic utility of cytology samples for ploidy analysis.

METHODOLOGY

After obtaining ethical clearance and consent, tissue and cytology samples of leukoplakia were collected and grouped based on the dysplastic findings into low-risk (n=20) and high-risk (n=20). DNA ploidy analysis was done using high resolution flow cytometry and its diagnostic utility was assessed.

RESULTS

Diagnostic utility was expressed in terms of sensitivity, specificity, PPV and NPV. On comparing the ploidy status of individual cases between tissue and cytology samples, cytology was able to accurately determine the ploidy status in majority of the cases. In the low-risk group, cytology had a sensitivity and specificity of 100% and a PPV and NPV of 100% with an overall diagnostic accuracy of 100%. Among the high-risk group, cytology had a sensitivity of 80% and specificity of 100% with a PPV of 100% and NPV of 83.33% and had an overall diagnostic accuracy of 90%. Combining both groups together, it had a sensitivity of 85.71% and specificity of 100% with a PPV of 100% and NPV of 92.31% and had an overall diagnostic accuracy of 94.74%.

CONCLUSION

Overall, this study showed a positive correlation between cytology and tissue samples and ploidy and grade of dysplasia and cytology proved to be a simple and efficient with a reasonable diagnostic value.

Up-regulation of CNDP2 facilitates the proliferation of colon cancer

BACKGROUND

Cytosolic nonspecific dipetidase (CN2) belongs to the family of M20 metallopeptidases. It was stated in previous articles that higher expression levels of CN2 were observed in renal cell carcinoma and breast cancer. Our study explored the correlation between CN2 and colon carcinogenesis.

METHODS

We analysed the relationship between 183 patients clinicopathological characteristics and its CN2 expression. To detect the levels of CN2 in colon cancer cell lines and colon cancer tissues by western blot. To verify cell proliferation in colon cancer cells with knockdown of CNDP2 and explore the causes of these phenomena.

RESULTS

The expression levels of CN2 in clinical colon tumors and colon cancer cell lines were significantly higher than that in normal colon mucosa and colon cell lines. The difference in CN2 levels was associated with tumor location (right- and left-sided colon cancer), but there was no significant association with age, gender, tumor size, tumor grade, tumor stage or serum carcinoembryonic antigen (CEA). Knockdown of CNDP2 inhibited cell proliferation, blocked cell cycle progression and retarded carcinogenesis in an animal model. The signaling pathway through which knockdown of CNDP2 inhibited cell proliferation and tumorigenesis involved in EGFR, cyclin B1 and cyclin E.

CONCLUSIONS

Knockdown of CNDP2 can inhibit the proliferation of colon cancer in vitro and retarded carcinogenesis in vivo.

Correlation between histological grading and ploidy status in potentially malignant disorders of the oral mucosa: A flow cytometric analysis

Background:

Histopathological grading of oral dysplastic lesions is the method of choice for evaluating malignant and potentially malignant disorders. Owing to inter- and intra-observer variability, determination of the DNA ploidy status of lesions may serve as an adjunct in the prediction of malignant transformation.

Aim:

To correlate histopathological grading and ploidy status in potentially malignant and malignant disorders of the oral mucosa.

Settings and Design:

A pilot study was done with 30 patients (10 patients with oral potentially malignant disorders predominantly leukoplakia, 10 patients with oral malignant lesions and 10 patients with normal mucosa).

Materials and Methods:

Incisional biopsy was done after isolating the biopsy site with 1% Toluidine blue staining. Two sections of the tissue were removed and sent for histopathological and Flow-cytometric analysis respectively. Histopathological diagnosis was obtained and compared with Flow-cytometric results which were graded as diploid and aneuploid. Further, the S – phase fraction, DNA index were also calculated to evaluate the severity of malignant transformation or malignancy.

Statistical Analysis:

The results were analyzed using Pearson Chi-Square Test.

Results:

There exists a significant correlation between histopathology and ploidy status in both potentially malignant and malignant group. (P = 0.002).

Conclusion:

The data from this study has shown that DNA Ploidy analysis can be used as a valuable tool in assessing the carcinomatous progression of potentially malignant and malignant lesions.

Chromosomal instability, aneuploidy and routine high-resolution DNA content analysis in oral cancer risk evaluation

Carcinogen exposure of the oral cavity is thought to create an extensive 'field cancerization'. According to this model, a very early precursor of oral cancer is a patch of normal-appearing mucosa in which stem cells share genetic/genomic aberrations. These precancerous fields then become clinically visible as white and red lesions (leuko- and erythro-plakias), which represent the vast majority of the oral potentially malignant disorders. This review focuses on aneuploidy (where it is from) and on biomarkers associated with DNA aneuploidy in oral mucosa and oral potentially malignant disorders, as detected by DNA image and flow cytometry. Data from the literature strongly support the association of DNA ploidy with dysplasia. However, work is still needed to prove the clinical value of DNA ploidy in large-scale prospective studies. Using high-resolution DNA flow cytometry with fresh/frozen material and the degree of DNA aneuploidy (DNA Index) might improve the prediction of risk of oral cancer development.

Correlation between dysplasia and ploidy status in oral leukoplakia

Oral leukoplakia and other potentially malignant disorders (PMD) may progress to oral squamous cell carcinoma (OSCC). The gold standard for assessing the potential for malignant transformation remains histologic examination with the aim of grading the dysplastic changes. However, not all lesions with dysplasia will progress to OSCC. DNA ploidy has been suggested as a method to predict the clinical behaviour of PMD. This study reports on the use of high-resolution flow cytometry to determine the ploidy status of formalin-fixed, paraffin-embedded material from PMD compared to their dysplasia grade on histology. Aneuploidy was found in 13 % of mild, 31 % of moderate, and 54 % of severe dysplasia cases. This difference was statistically significant (p = 0.011). The differences in ploidy status were more significant when grouping the dysplasia into low-risk and high-risk categories (p = 0.008). These findings indicate that the ploidy status of PMD as determined by high-resolution flow cytometry may be of value in predicting biological behaviour in PMD such as leukoplakia.

Chromosomal aberrations and aneuploidy in oral potentially malignant lesions: distinctive features for tongue

BACKGROUND

The mucosae of the oral cavity are different at the histological level but appear all equally exposed to common genotoxic agents. As a result of this exposure, changes in the mucosal epithelia may develop giving rise to Oral Potentially Malignant Lesions (OPMLs), which with time may in turn progress to Oral Squamous Cell Carcinomas (OSCCs). Therefore, much effort should be devoted to identify features able to predict the likeliness of progression associated with an OPML. Such features may be helpful in assisting the clinician to establish both appropriate therapies and follow-up schedules. Here, we report a pilot study that compared the occurrence of DNA aneuploidy and chromosomal copy number aberrations (CNAs) in the OPMLs from different oral anatomical subsites.

METHODS

Samples from histologically diagnosed OPMLs were processed for high resolution DNA flow cytometry (hr DNA-FCM) in order to determine the relative DNA content expressed by the DNA index (DI). Additionally, array-Comparative Genomic Hybridization (a-CGH) analysis was performed on DNA obtained from diploid nuclei suspensions directly. When aneuploid nuclei were detected, these were physically separated from diploid nuclei on the base of their DI values by means of a DNA-FCM-Sorter in order to improve the a-CGH analysis.

RESULTS

Tongue OPMLs were more frequently associated with DNA aneuploidy and CNAs than OPMLs arising from all the other mucosal subsites.

CONCLUSIONS

We suggest that the follow-up and the management of the patients with tongue OPMLs should receive a distinctive special attention. Clearly, this hypothesis should be validated in a prospective clinical study.