CD82, a member of the tetraspanin superfamily, has been proposed to exert its activity via tetra‐transmembrane protein enriched microdomains (TEMs) in exosomes. The present study aimed to explore the potential of the exosome protein CD82 in diagnosing breast cancers of all stages and various histological subtypes in patients. The results strongly suggest that CD82 expression in breast cancer tissue was significantly lower than that in healthy and benign breast disease tissues. There was a significant negative correlation between CD82 expression in tissues and CD82 content in exosomes, which indicated that CD82 expression was redistributed from tissues to the blood with the development and metastasis of breast cancer.

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Background: CD82/KAI-1 which is a member of the tetraspanin superfamily, has been proposed to exert its activity via the Tetraspanin Web. However, the mechanism of CD82 palmitoylation in this web has not been fully elucidated. The purpose of this study is to investigate cell migration and apoptosis by mutation of tetraspanin CD82 palmitoylation. Methods: This study elucidated the impact of various palmitoylation site mutations on apoptosis in breast cancer cells through a comprehensive approach involving RT-PCR, Western blotting, TUNEL assay, immunofluorescence, and tumor formation assay in athymic nude mice model. Results: We found that the mutation of CD82 palmitoylation at cys74 and cys83 or cys5 and cys74 and cys83 simultaneously increased apoptosis in breast cancer. However, the other forms of mutation of CD82 palmitoylation showed no effects on apoptosis. Conclusion: The study strongly implicate that CD82 palmitoylation at cys74 and cys83 are both closely related to maintain biological function.