Mn-based cGAS-STING activation for tumor therapy

Immunotherapy has efficiently revolutionized the treatment of human neoplastic diseases.However,the overall responsive rate of current immunotherapy is still unsatisfactory,benefiting only a small proportion of patients.Therefore,significant attention has been paid to the modulation of tumor microenvironment(TME)for the enhancement of immunotherapy.Interestingly,recent studies have shown that cyclic GMP-AMP synthasestimulator of interferon gene(cGAS-STING)was initially found as an innate immune sensor to recognize cytoplasmic DNA(such as bacterial,viral,micronuclei,and mitochondrial).It is a promising signaling pathway to activate antitumor immune responses via type I interferon production.Notably,Mn^(2+)was found to be a critical molecule to sensitize the activation of the cGAS-STING pathway for better immunotherapy.This activation led to the development of Mn^(2+)-based strategies for tumor immunotherapy via the activation of the cGAS-STING pathway.In this critical review,we aimed to summarize the recent progress of this field,focusing on the following three aspects.First,we briefly introduced the signaling pathway of cGAS-STING activation,and its regulation effect on the antitumor immunity cycle has been discussed.Along with this,several agonists of the cGAS-STING pathway were introduced with their potential as immunotherapeutic drugs.Then,the basic biological functions of Mn^(2+)have been illustrated,focusing on its critical roles in the cGAS-STING pathway activation.Next,we systematically reviewed the Mn^(2+)-based strategies for tumor immunotherapy,which can be classified by the methods based on Mn^(2+)alone or Mn^(2+)combined with other therapeutic modalities.We finally speculated the future perspectives of the field and provided rational suggestions to develop better Mn^(2+)-based therapeutics.