Immune surveillance cells in the tumor microenvironment play an important role in inhibiting tumorigenesis and metastasis, but their anti-tumoral effects are impaired. The anti-tumoral effects of innate immune cells and adaptive immune cells in the immune microenvironment of gastric cancer are also impaired. Their degree of functional impairment is closely related to the prognosis of gastric cancer. Multiple factors inhibit the anti-tumoral effects of immune surveillance cells, such as decreased numbers of immune surveillance cells, reduced activating receptors, decreased secretion of pro-inflammatory cytokines, increased apoptosis, elevated expression of coinhibitory molecules on cancer cells or immunosuppressive cells, increased secretion of inhibitory cytokines, impaired antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by antigen-presenting cells (APCs) and pro-tumoral polarization of cells with functional plasticity. These factors can potentially combine to suppress the immune surveillance cells' functions. However, there are conflicting conclusions on the effects of immune surveillance cells on gastric cancer cells. These contradictions are partly due to the heterogeneity of the tumor microenvironment.
Keywords: Gastric cancer; Heterogeneity; Immune surveillance cells; Tumor microenvironment.
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