Effect of exosome biomarkers for diagnosis and prognosis of breast cancer patients

Exosomes are gradually detected as an indicator for diagnosis and prognosis of breast cancer in clinic and a systematic review was conducted. A search for clinical studies published before July 1, 2017 was performed. Methods of exosome purification and identification from all studies were extracted. For diagnosis evaluation, the comparison of exosome biomarkers expression between breast cancer patients and healthy women was obtained; for prognosis prediction, the correlation between exosome biomarkers expression and chemotherapy resistance, overall survival (OS), disease-free survival (DFS), recurrence and metastasis of breast cancer was also extracted. A total of 11 studies with 921 breast cancer patients were included. Ultracentrifugation is the most frequent method to purify exosomes and transmission electron microscopy is commonly used to identify exosomes. Exosome biomarkers (such as HER2, CD47, Del-1, miR-1246 and miR-21) in breast cancer patients are significantly higher than those in healthy controls, exosomal GSTP1 and TRPC5 are related to chemotherapy resistance, exosome-carrying TRPC5, NANOG, NEUROD1, HTR7, KISS1R and HOXC are correlated to PFS, DFS or OS, and some exosomal proteins (HER2, KDR, CD49d, CXCR4 and CD44) as well as miRNAs (miR-340-5p, miR-17-5p, miR-130a-3p, miR-93-5p) are associated with tumor recurrence or distant organ metastasis. Exosome biomarkers can be used for early diagnosis and prognosis of breast cancer patients in clinic.