Prognostic value of circulating CD133 + cells in patients with gastric cancer

Objectives Gastric cancer is an important cause of cancer‐related mortality worldwide (1). There is increasing evidence that the existence of cancer stem cells ( CSC ) is responsible for tumour formation and maintenance. Materials and methods The present study was designed to recognise circulating CSC s from blood samples of patients with gastric cancer, using CD 133 and ABCG 2 as potential markers. CD133 − , CD133 +  ABCG2 − and CD133 +  ABCG2 + cells lines were analysed by flow cytometry, immunofluorescence staining, western blotting and real‐time PCR . Furthermore, functional assays (clonogenic assay in vitro and tumourigenic assay in vivo ) were also performed using these cell lines. Results Higher percentages of CD133 + cells were identified in blood samples from gastric cancer patients compared to normal controls. In addition, we found by using Kaplan–Meier analysis, that numbers of CD133 + cells correlated with poor prognosis gastric cancer patients. Finally, tumourigenic properties of CD133 +  ABCG2 + cells were determined in vitro and in vivo . Conclusions Our in vitro and in vivo experiments demonstrated that CD133 +  ABCG2 + cells exhibited well‐known CSC characteristics; thus when circulating they could be used as a prognostic marker for gastric cancer.