Identification and Evaluation of Cancer Stem Cells in Oral Squamous Cell Carcinoma and Oral Epithelial Dysplasia Using NANOG: An Immunohistochemical Study

BACKGROUND

Squamous cell carcinoma of the oral cavity may show precursor lesions, termed as potentially malignant disorders, of which leukoplakia is the most frequent one. Oral leukoplakia is a clinical diagnosis for which the histological diagnosis may be either hyperplasia or oral epithelial dysplasia (OED) and sometimes even oral squamous cell carcinoma (OSCC). Cancer stem cells (CSCs), identified in various tumors, are a specific group of cells that exhibit the properties of self-renewal and differentiation. Among the various biomarkers that identify CSCs, the transcription factor NANOG is considered to be a significant one.

AIM

In this study, we intend to identify and compare the immunohistochemical expression of NANOG in OSCC, OED, and normal oral mucosa.

METHODOLOGY

Tissue blocks of OSCC (n=28), OED (n=28), and normal oral mucosa (n=28) were used in this study. Specimens were immunohistochemically analyzed for NANOG expression. The results were statistically analyzed using one-way ANOVA, Games-Howell post hoc, and Student t-test. Statistical Product and Service Solutions (SPSS, version 21; IBM SPSS Statistics for Windows, Armonk, NY) software was used for performing the statistical analysis, and the level of significance was set as 0.05.

OBSERVATIONS

NANOG expression was higher in OSCC when compared to oral dysplasias and normal oral mucosa, in decreasing order. A significantly higher histo-score and labeling index score were observed in OSCC and oral dysplasias compared to normal oral mucosa (p=<0.001).

CONCLUSION

The expression levels of NANOG were positively correlated with disease progression in OSCC, implicating that NANOG can be used as a surrogate marker of oral oncogenesis and prognosis. Therefore, decoding the molecular mechanisms of NANOG regulation in the progression of cancer helps in developing new therapeutic strategies for oral cancer.

The study of elastic fibres in oral precancerous and cancerous lesions using Shikata's modified orcein stain: a retrospective study

Statement of the problem

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer. During the invasion, tumour cells break through the basement membrane and penetrate the connective tissue to interact with the extracellular matrix. An attempt was made to evaluate the connective tissue changes in different grades of OSCCs, oral submucous fibrosis (OSMF) and Oral Epithelial Dysplasias. Literature related to the evaluation of malignant epithelial cells is vast but very sparse knowledge is available on the role of extracellular stromal fibres on tumour invasion in oral cancer and precancer especially on elastic fibres using Shikata's Modified Orcein Stain.

Purpose

To analyse the changes in elastic fibres in varying grades of OSCC, OSMF and Oral Epithelial Dysplasias using a special stain, Shikata's modified orcein stain.

Materials and method

A total of 100 cases were selected as the study group in this retrospective observational study. One section each was cut from 50 samples of varying grades of OSCC and 50 samples of varying grades of OSMF and oral leukoplakia. Ten samples of the control group were taken from the archives of the Department of Oral Pathology. Qualitative and quantitative analysis of elastic fibres was accomplished using set criteria. Spearman's test was done to evaluate the elastic fibres. Statistically insignificant results were obtained for quantitative and qualitative analysis of elastic fibres.

Results

A change in density in elastic fibres was observed in progression from early to advanced grades of OSCC, OSMF and oral epithelial dysplasia cases. A low expression of elastic fibres in tumour stoma indicates that the protective barrier against tumour progression is deficient, allowing the tumour to progress more easily and resulting in a poorer prognosis.

Conclusion

The elastic fibres undergo a change in density, orientation and packing in the stroma of varying grades of OSCC, OSMF and oral epithelial dysplasia cases. The unique feature of this study lies in the exploration of elastic fibres in OSCC which has not been done so far.