CD44 is commonly used as a cell surface marker of cancer stem-like cells in epithelial tumours, and we have previously demonstrated the existence of two different CD44(high) cancer stem-like cell populations in squamous cell carcinoma, one having undergone epithelial-to-mesenchymal transition and the other maintaining an epithelial phenotype.
We have examined by immunohistochemistry the expression of CD44 in cutaneous invasive and metastatic squamous cell carcinomas, metastatic adenocarcinomas, and basal cell carcinomas.
Among patients with squamous cell carcinoma, the only molecular marker associated with decreased cancer-specific survival is erbB-2; among patients with adenocarcinoma (AC), there are three markers: p53, CD-44, and factor viii.
Staining of CD29 and CD44 showed similar heterogeneous expression pattern with positive cells located in the invasion front of SCC tissue as well as in cultured A431 cells.
The purpose of the present study was to investigate the microscopic and phenotypic characteristics of OSCC tumors induced after orthotopic xenoimplantation of SCC9<sup>WT</sup> cell line and CSC-enriched subpopulation isolated from SCC9 cell line based on high expression of the putative CSC marker CD44.
CD44 variant 6 expression was most frequently observed in squamous cell carcinoma (P = 0.00058); 15 (79%) of 19 squamous cell carcinoma cases were positive, as were five (22%) of 23 adenocarcinoma cases and two (67%) of three large cell carcinoma cases.
The CD44rs187115 polymorphism has potential predictive significance in oral carcinogenesis and also may be applied as factors to predict the clinical stage in OSCC patients.
Increased expression of CD44 was significantly correlated with higher grade tumors which correspond to poor prognosis in SCC (P=0.012) and the lower level of CD44 expression was more often found in well differentiated ADC tumors (P=0.03).
RT-qPCR results indicated that the mRNA expression of CDH6, CDH11 and CD44 was increased in OSCC patients with lymph node metastasis (2.93-, 2.01- and 1.92-fold; P<0.05).
Both CD44(high)CD90(+) and CD44(high)CD90(-) cells in the PLCCL derived from SCC formed spheroids, whereas the CD44(low/-) cells were lacking this potential.
A higher level of CD44 expression was more often found in melanoma tumor cells with a higher rate of recurrence (p = 0.029) and in SCC cases with ulceration (p = 0.01), while there was no significant correlation between ALDH1A1 expression and other clinicopathological parameters.