Identification and modification of an HLA-A*0201-restricted cytotoxic T lymphocyte epitope from Ran antigen
1Department of Immunology, Institute of Immunology, Third Military Medical University, Chongqing, China.
Abstract:
Ran is considered to be a promising target for tumor-specific immunotherapy because its protein is exclusively expressed in tumor tissues, though its mRNA can be expressed in most normal tissues. In our study, we obtained four candidate wild-type epitopes designated Ran1, Ran2, Ran3, and Ran4, derived from the Ran antigen with the highest predicted affinity with MHC-I, indicated by affinity prediction plots and molecular dynamics simulation. However, in vitro affinity assays of these epitopes showed only a moderate affinity with MHC-I. Thus, we designed altered peptide ligands (APLs) derived from Ran wild-type epitopes with preferred primary and auxiliary HLA-A*0201 molecule anchor residue replacement. Of the eight tested peptides, the 1Y analog had the strongest binding-affinity and lowest-dissociation rate to HLA-A*0201. Additionally, we investigated the CTLs activities induced by Ran wild-type peptides and the APLs in human PBMCs and in HLA-A*0201/K(b) transgenic mice. Ran1 1Y was superior to other APLs and wild-type peptides in eliciting epitope-specific CTL immune responses both in vitro and in vivo. In summary, a wild-type epitope of the tumor-specific antigen Ran, expressed broadly in many tumors, was identified and designated Ran1. An APL of Ran1, Ran1 1Y, was further designed and verified in vitro and in vivo and found to elicit a stronger Ran-specific CTL response, indicating a potential anti-tumor application in the future.
Insights
Researchers identified Ran1, a tumor antigen epitope, and designed an enhanced version, Ran1 1Y. This altered peptide ligand significantly boosts tumor-specific T-cell responses, showing promise for future cancer immunotherapies.
Area of Science:
- Oncology
- Immunology
- Biochemistry
Background:
- Ran protein is a tumor-specific antigen, making it a potential target for cancer immunotherapy.
- Existing wild-type epitopes derived from Ran show moderate affinity to MHC-I molecules.
Purpose of the Study:
- To identify and characterize novel wild-type epitopes from the Ran antigen.
- To design and evaluate altered peptide ligands (APLs) for enhanced binding affinity and T-cell activation.
- To assess the in vitro and in vivo efficacy of Ran-derived epitopes and APLs in eliciting cytotoxic T-lymphocyte (CTL) responses.
Main Methods:
- Bioinformatic prediction and molecular dynamics simulations to identify high-affinity Ran epitopes.
- In vitro affinity assays to assess epitope binding to MHC-I.
- Design of APLs by modifying anchor residues for improved HLA-A*0201 binding.
- In vitro and in vivo studies using human peripheral blood mononuclear cells (PBMCs) and transgenic mice to evaluate CTL activity.
Main Results:
- Four wild-type Ran epitopes (Ran1, Ran2, Ran3, Ran4) were identified, with Ran1 showing promise.
- The APL derived from Ran1, named Ran1 1Y, exhibited superior binding affinity and lower dissociation rate to HLA-A*0201 compared to other analogs.
- Ran1 1Y demonstrated significantly stronger epitope-specific CTL immune responses in vitro and in vivo compared to wild-type peptides and other APLs.
Conclusions:
- Ran1 is a validated wild-type epitope from the broadly expressed tumor antigen Ran.
- The designed APL, Ran1 1Y, enhances Ran-specific CTL responses, indicating its potential for anti-tumor immunotherapy applications.
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