CD14, a novel surface marker of esophageal cancer stem cells

Studies on targeting cancer stem cells (CSCs) have not yielded satisfactory results regarding solid tumor treatments; one of the reasons for this is the difficulty associated with the identification of a relatively specific antigen in solid tumors. CD14, which is mainly expressed in certain immune cells, is associated with tumor recurrence, growth, metastasis and resistance to treatment, which is in conformity with the characteristics of CSCs. It was thus hypothesized that esophageal CSCs (ECSCs) express CD14. In the present study, paraffin‑embedded sections of human esophageal carcinoma were used to determine the co‑expression of CD14 and the ECSC marker aldehyde dehydrogenase‑1 (ALDH1) using immunofluorescence. CD14⁺ cells were then isolated using immunomagnetic separation for stemness detection, including proliferation, migration, invasion and tumorigenicity. Cell Counting Kit‑8 (CCK‑8), EdU and colony‑formation assays were utilized to investigate the proliferative ability, the metastatic capacity was examined using Transwell and wound‑healing assays and a xenograft assay was performed to investigate the tumorigenic ability. It was indicated that the ALDH1‑labeled ECSCs expressed CD14 and primary CD14⁺ cells possessed the characteristics of CSCs. On the whole, the results of the present study suggest the potential utility of CD14 as a novel surface marker for ECSCs.