View source for File:Immunohistochemical expression of CD44 and aldehyde dehydrogenase 1 in oral submucous fibrosis and oral squamous cell carcinoma.pdf


              	In potentially malignant disorders and oral squamous cell carcinomas (OSCC), hyaluronan receptor cluster of differentiation 44 (CD44) and aldehyde dehydrogenase 1 (ALDH1) were often used as cancer stem cell (CSC) markers. Prevalence of OSCC was high in Asian countries, especially in South and Southeast Asia; cancers of the oral cavity were thought to progress from premalignant lesions, beginning as hyperplastic tissue and developing into invasive squamous cell carcinoma. Oral submucous fibrosis (OSMF) was a one of the well-known potentially malignant disorders that its prevalence rate was high in Asian continents and its malignant transformation rate was 7-30% with a long-term follow-up study recording an annual malignant transformation rate of 0.5%. 
 	The aim of the present study was to identify and compare CD44 and ALDH1 protein markers in relation with pathological variance of OSMF and OSCC. Thirty specimens of OSMF and 34 specimens of OSCC patients with primary OSCC, from the Department of Oral Medicine, University of Dental Medicine, Yangon, were analyzed cross-sectional study for the expression of CD44 and ALDH1. CD44 was expressed in 80% of OSMF and 58.82% of OSCC samples while ALDH1 was expressed in 56.67% of OSMF and 55.88% of OSCC samples. CD44 and ALDH1 expression patterns were not completely overlapping within OSMF and OSCC cases.  Co-expression of CD44 and ALDH1 in OSMF was 56.67% while 41.18% in OSCC. Kruskal-Wallis test for CD44 and ALDH1 in OSMF was 8.980 (p = .030) and 12.565 (p = .028) while Kruskal-Wallis test for CD44 and ALDH1 in OSCC was 8.304 (p = .081) and 5.900 (p = .207). CD44 and ALDH1 showed lesser expression in association with lymphoplasmacytic infiltration at the epithelial-connective tissue junction of OSMF. Correlation of CD44+/ALDH1+ cells and lymphoplasmacytic infiltration in OSCC was statistically significant (p = .026).
	In conclusion, CD44 and ALDH1 expression showed a more distinct distribution pattern in potentially malignant lesion, OSMF. However, these markers were not sufficient to precisely isolate the CSC subpopulation from the tumor bulk. Further protein marker was needed to precisely define the CSC subpopulations in OSMF and OSCC. The finding of ALDH1- and CD44-positive cells in epithelium of OSMF and in adjacent non-tumor epithelium as well as tumor portion of OSCC suggests that changes were already underway, as these enzymes tend to be present in cells with a high tumorigenic potential. Tumor-host immune reaction took part an important role in expression of these markers in oral squamous cell carcinoma.