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Fig. 3 | Molecular Cancer

Fig. 3

From: STING: a master regulator in the cancer-immunity cycle

Fig. 3

The positive and negative roles of STING activation in antitumor immune response. On the one hand, STING facilitates antitumor immune response through promoting the infiltration of effector cells and eradication of tumor cells. On the other hand, constant STING activation may hamper immune response by inducing the infiltration of immune suppressive cells, such as Treg and MDSC, and upregulating the expression of PD-L1 on tumor cells and PD-1 on T cells. Moreover, STING activation is associated with the enhanced activity of IDO, an enzyme catalyzing the transformation of tryptophan into kynurenine. Diminished tryptophan restricts the proliferation of T cells whereas elevated kynurenine promotes differentiation of Tregs but hampers antigen presenting ability of DCs. Additionally, aberrant STING activation also directly inhibits T cell proliferation and even promotes apoptosis of lymphocytes

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