Evaluating stem and cancerous biomarkers in CD15+CD44+ KYSE30 cells

Digestive system cancers are listed among the ten top causes of cancer-related death worldwide. Cancer stem cells (CSCs) are malignant cells that share some of their characteristics with normal stem cells, including self-renewal and multipotency, and also cancer cells, such as drug resistance and metastasis. Despite many reports on CSCs with digestive system origin, identification and characterization of esophageal CSCs have remained elusive. To examine the validity of routine SC, cancer cell and CSC markers in KYSE30 cells, derived from esophageal carcinoma, cells were first characterized by immunofluorescence and RT-PCR techniques, and then the significance of candidate biomarkers was evaluated in retinoic acid-treated cells by flow cytometry and/or real-time RT-PCR. Meanwhile, to study CD15 (a newly introduced CSC marker) expression in digestive tract cancers, human normal and tumoral tissues of esophagus, stomach, and colon were analyzed by immunohistochemistry. Using several experimental approaches, we show that CD44, but not CD15, could serve as a reliable marker for undifferentiated malignant squamous cells of esophagus. In conclusion, our study confirms the role of CD44 as a CSC marker in KYSE30 cells, an esophageal squamous cell carcinoma cell line, and for the first time indicates the expression of CD15 in non-neural stem-like cancer cells. Although the importance of CD15 was not indicated in diagnosis of digestive cancers, further studies are needed to better understand the biological identity and function of this molecule in non-neural malignancies.