Immunohistochemical expression of putative cancer stem cell markers aldehyde dehydrogenase 1, SOX2, CD44 and OCT4 in different grades of oral epithelial dysplasia

OBJECTIVES: The hypothesized existence of cancer stem cells (CSC) and its markers aldehyde dehydrogenase 1 (ALDH1), CD44, SOX2 and OCT4 in oral dysplastic tissues provides the potential for a more reliable assessment of malignant transformation of oral epithelial dysplasia (OED). Thus, the present study is intended to evaluate the immunohistochemical expression of four different CSC markers ALDH1, CD44, SOX2 and OCT4 in different grades of OED and to investigate the co-expression of these putative stem cell markers in OED. SUBJECTS AND METHODS: A total of 35 samples of varying grades of OED which included 7 mild, 11 moderate and 17 severe dysplasia samples and 10 samples of normal oral mucosa without dysplasia were used. Four sections each from all 45 samples were stained with ALDH1, CD44, SOX2 and OCT4, respectively, by immunohistochemistry. The acquired data were analyzed and evaluated using the Chi-square test and unpaired t-test and the P < 0.05 was taken significant. RESULTS: ALDH1 and SOX2 expression percentages showed statistically significant differences among study groups (P < 0.05). Statistical comparison of percentage expression of CD44 and OCT4 between OED and normal was nonsignificant (P > 0.05). Co-expression of all four markers was found in 15 cases of OED with none of the normal cases showing co-expression. CONCLUSION: The expression of CSC markers in OED and normal mucosa differs significantly with co-expression of all four markers located only in dysplastic tissues. Until now, no single protein marker has been able to unequivocally identify the CSCs. Thus, a panel of putative CSC markers will help in identifying the patients with high risk for malignant transformation in OED.