Provided are a polypeptide and nucleic acid for encoding the polypeptide, a nucleic-acid construct, an expression vector, and a host cell containing the nucleic acid, an antigen-presenting cell presenting the polypeptide on the surface of the cell, and immune effector cell thereof, a pharmaceutical composition containing the polypeptide, a vaccine containing the nucleic acid, the nucleic acid construct, the expression vector, the host cell, the antigen-presenting cell, and the immune effector cell, and an antibody recognizing the polypeptide. Also provided is a therapeutic method using the polypeptide, the nucleic acid, the pharmaceutical composition, the vaccine, and the antibody. Also provided are a diagnosis method and diagnosis apparatus for detecting the described polypeptide. Also provided is an application of the polypeptide in preparing a vaccine, a tumor diagnosis kit, or a pharmaceutical composition, and an application of the polypeptide or the nucleic acid as a test target in tumor diagnosis.