Lgr5 expression as stem cell marker in human gastric gland and its relatedness with other putative cancer stem cell markers

- Lgr5 + cells exist at base of gland units in normal gastric mucosa.
- Lgr5 was differentially expressed in varying stages of differentiation of cancer.
- Lgr5 and Bmi1 were co-expressed within the same cells of gastric glands.
- CD26 +, CD44 +, ALDH1 + and CD133 + cells co-existed with Lgr5 + cells.

To explore Lgr5 as the possible stem cell marker in human gastric tissue, 259 normal gastric tissues and dissected gastric adenocarcinoma were analyzed by immunohistochemistry, immunofluorescence double staining and qRT-PCR. The results demonstrated that Lgr5 was expressed in the bottom of the normal gastric gland units, and showed a differential expression in gastric adenocarcinoma with varying differentiation. Lgr5 and Bmi1 were co-expressed within the same cells of gastric glands. CD26 +, CD44 +, ALDH1 + and CD133 + cells co-existed with Lgr5 + cells in the stem cell zone of adjacent normal gastric mucosa, and they were detectable in gastric adenocarcinoma but behaved differently. We concluded that Lgr5 may be the adult stem cell marker in human gastric epithelium; Lgr5 and Bmi1 may belong to the same stem cell population; Lgr5, CD26, CD44, ALDH1, and CD133 may be functionally-associated.