Bone marrow-derived mesenchymal stem cells increase drug resistance in CD133-expressing gastric cancer cells by regulating the PI3K/AKT pathway.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are recruited to primary tumours to compose the tumour microenvironment. In various cancers, CD133-positive cells have been shown to possess cancer stem cell properties that confer chemoresistance. This study aimed to investigate the role of BM-MSCs in the anti-tumour drug resistance of CD133-expressing gastric cancer cells and explore the underlying mechanisms that governing this role. We found that CD133 gastric cancer cells displayed more resistance to chemotherapeutics than CD133 cells. In addition, BM-MSCs increased the anti-apoptotic abilities and chemoresistance of CD133 cells via upregulation of Bcl-2 and downregulation of BAX. Mechanistically, BM-MSCs triggered activation of the PI3K/Akt signalling cascade in CD133 cells. Blocking the PI3K/Akt pathway inhibited the promotion of chemoresistance. Furthermore, BM-MSCs enhanced the drug resistance of CD133-overexpressing cells in vitro and in vivo, but not that of CD133-knockdown cells, which demonstrated the contribution of CD133 to this process. In conclusion, we demonstrated that BM-MSCs increased the anti-apoptotic abilities and drug resistance of CD133-expressing cells via activation of the PI3K/Akt pathway following Bcl-2 upregulation and BAX downregulation, in which CD133 played a significant role. Targeting this route may help improve the efficacy of chemotherapy in gastric cancer.