Abstract: Objective To explore the clinical and prognostic value of serum exosomal LncRNA HOTTIP in patients with breast cancer (BC). Methods Exosomes were extracted from serum samples of 98 BC patients, 50 benign breast disease (BBD) patients and 50 healthy subjects by kit, and the expression level of HOTTIP in the serum exosomes was detected by RT-qPCR. Furthermore, the relationship among the expression level of HOTTIP, the clinicopathological features and the overall survival was analyzed. Results The expression level of HOTTIP in serum exosomes of the BC patients was significantly higher than that of the BBD patients (t = 8. 790, P< 0. 001) and that of the normal healthy people (t = 11. 540, P< 0. 001), and the level of HOTTIP in serum exosomes of the BC patients significantly decreased after surgery ( t = 14. 570, P < 0. 001 ) . Clinicopathological analysis showed that high serum exosomal HOTTIP level was significantly correlated with HER2 expression level, lymph node metastasis and TNM stage ( all P < 0. 05). Further survival analysis showed that the 5-year survival rate of BC patients in the high serum exosomal HOTTIP expression group was significantly lower than that in the low HOTTIP expression group (χ 2 = 5. 548, P = 0. 019). Moreover, multivariate analysis demonstrated that high expression level of serum exosomal HOTTIP was an independent risk factor for the poor prognosis of BC (HR = 2. 454, 95 % CI: 1. 142-7. 005, P = 0. 031 ). Conclusion The expression of serum exosomal lncRNA HOTTIP is up-regulated in BC, and its high expression indicates the malignant progression of cancer and poor prognosis of BC patients, which implies that serum exosomal lncRNA HOTTIP could be a non-invasive biomarker for the the assessment of prognosis in BC patients. 

Key words: breast cancer, lncRNA HOTTIP, exosome, clinicopathological features, prognosis