Identification and optimization of peptide inhibitors to block VISTA/PSGL-1 interaction for cancer immunotherapy

Developing new therapeutic agents for cancer immunotherapy is highly demanding due to the low response ratio of PD-1/PD-L1 blockade in cancer patients. Here, we discovered that the novel immune checkpoint VISTA is highly expressed on a variety of tumor-infiltrating immune cells, especially myeloid derived suppressor cells (MDSCs) and CD8+ T cells. Then, peptide C1 with binding affinity to VISTA was developed by phage displayed bio-panning technique, and its mutant peptide VS3 was obtained by molecular docking based mutation. Peptide VS3 could bind VISTA with high affinity and block its interaction with ligand PSGL-1 under acidic condition, and elicit anti-tumor activity in vivo. The peptide DVS3-Pal was further designed by d-amino acid substitution and fatty acid modification, which exhibited strong proteolytic stability and significant anti-tumor activity through enhancing CD8+ T cell function and decreasing MDSCs infiltration. This is the first study to develop peptides to block VISTA/PSGL-1 interaction, which could act as promising candidates for cancer immunotherapy.

Expression and relationship of Beclin1 and Bci2 in invasive pituitary adenomas / 中华内分泌外科杂志

Objective To detect the expression of Beclin1 and Bcl2 in invasive pituitary adenomas and to explore the relationship of Beclin1 and Bci2 in invasive pituitary adenomas and the relativity between the 2 genes.Methods 61 specimens were classified into invasive group (32 cases) and non-invasive group (29 cases) according to the comprehensive evaluation of invasive pituitary adenomas.lmmunofluorescence analysis and RT-PCR were adopted respectively to detect the protein and mRNA expressions of Beclinl and Bcl2.The difference and relativity of Beclin1 and Bcl2 expression in invasive group and non-invasive group were analyzed.Results 32 specimens of pituitary adenoma were invasive and 29 were non-invasive.Beclin1 protein and mRNA expressions were lower in the invasive group than in the non-invasive group (P ＜0.01 ).Bcl2 protein and mRNA expressions were higher in the invasive group than in the non-invasive group (P ＜0.01 ).Pearson related analysis showed that Beclin1 mRNA expression was negtively correlated with Bcl2 mRNA expression in the invasive group ( r =-0.42,P =0.028 ).Conclusions Beclinl expression is decreased in invasive pituitary adenomas.The invasiveness of pituitary adenoma is closely related to the high expression of Bcl2 protein and mRNA,and the low expression of Beclin1 protein and mRNA.The inhibition of the autophagy may lead to the enhancement of the invasiveness of pituitary adenomas and that inhibition may come from the interaction of Beclin1 and Bcl2.