Objectives: Gastric cancer mesenchymal stem cells (GC-MSCs) can promote the development of tumour growth. The tumour-promoting role of tumour-associated MSCs and T cells has been demonstrated. T cells as the major immune cells may influence and induce a pro-tumour phenotype in MSCs. This study focused on whether CD4+ T cells can affect GC-MSCs to promote gastric cancer growth.
Materials and methods: CD4+ T cells upregulation of programmed death ligand 1 (PD-L1) expression in GC-MSCs through the phosphorylated signal transducer and activator of transcription (p-STAT3) signalling pathway was confirmed by immunofluorescence, western blotting and RT-PCR. Migration of GC cells was detected by Transwell migration assay, and apoptosis of GC cells was measured by flow cytometry using annexin V/propidium iodide double staining. CD4+ T cell-primed GC-MSCs promoted GC growth in a subcutaneously transplanted tumour model in BALB/c nu/nu mice.
Results: Gastric cancer mesenchymal stem cells stimulated by activated CD4+ T cells promoted migration of GC cells and enhanced GC growth potential in BALB/c nu/nu xenografts. PD-L1 upregulation of GC-MSCs stimulated by CD4+ T cells was mediated through the p-STAT3 signalling pathway. CD4+ T cells-primed GC-MSCs have greater GC volume and growth rate-promoting role than GC-MSCs, with cancer cell-intrinsic PD-1/mammalian target of rapamycin (mTOR) signalling activation.
Conclusions: This study showed that GC-MSCs are plastic. The immunophenotype of GC-MSCs stimulated by CD4+ T cells has major changes that may influence tumour cell growth. This research was based on the interaction between tumour cells, MSCs and immune cells, providing a new understanding of the development and immunotherapy of GC.
© 2017 John Wiley & Sons Ltd.