CD44+/EPCAM+ cells detect a subpopulation of ALDH(high) cells in human non-small cell lung cancer: A chance for targeting cancer stem cells?

Objectives: Several studies demonstrated that aldehyde dehydrogenase (ALDH) and CD44 are the most considered cancer stem cells (CSC) markers. However, a comparison between ALDH high cells and CD44+ cells have been previously described with no significant correlation. Indeed, the aim of the present research is to identify a superficial marker able to match with ALDH high cells population in freshly isolated human lung cancer cells. Materials and Methods: This cross-sectional study analyzed the expression of ALDH(high/low) cells and the positivity for CD44 and epithelium cell adhesion molecule (EPCAM) antigens in surgical lung cancer tissues. The main approach was a cytofluorimetric analysis of ALDH expression and positivity for CD44/EPCAM on primary cell population obtained from 23 patients harboring NSCLC. Results: There was a highly positive correlation between the expressions of ALDH(high) and CD44+/EPCAM+ cells, with a Pearson’s correlation coefficient equal to 0.69 (95% CI 0.39–0.86; P = 0.0002), and Spearman’s correlation coefficient equal to 0.52 (P = 0.0124). The average paired difference between the expression of ALDH(high) and CD44+/EPCAM+ cells was very close to 0, being 0.1% (SD 2.5%); there was no difference between these subpopulations in terms of means (95% CI = –1.0; 1.2%, P = 0.8464). These results highlight a strong similarity between ALDH(high) and CD44+/EPCAM+ cells. Conclusions: Our study is the first attempt which identifies a high correlation between the ALDH(high) and the CD44+/EPCAM+ cells, thus suggesting the possibility to use this superficial marker for future target treatments against lung cancer stem cells.