Expression and clinical significance of serum exosome circ PVT1 and circ 0014606 in triple negative breast cancer

Data of 84 patients with breast cancer who underwent surgical treatment from January 2018 to December 2018 were retrospectively analyzed，including 46 patients with TNBC and 38 patients with non-triple-negative breast cancer（NTNBC）. Another 80 healthy people who underwent physical examination in our hospital during the same period were selected as the control group. The serum exosomes of all patients were extracted and identified by transmission electron microscopy and Western blot. The expression levels of circ PVT1 and circ 0014606 in exosomes of TNBC，NTNBC and control patients were detected by qRT-PCR. SPSS22.0 was used to analyze the data，and the relationship between the expression level of circ PVT1 and circ 0014606 and clinicpathological parameters of TNBC patients was analyzed by χ² or Fisher exact test. Kaplan-Meier survival curves were drawn to analyze the relationship between circ PVT1 and circ 0014606 expression and prognosis. P<0.05 was considered to be statistically significant.

Transmission electron microscopy（TEM）showed that the serum exosomes presented an elliptical bilayer vesicle structure. Western blot results showed that the expressions of exosome characteristic proteins CD9，CD63 and CD81 were significantly higher in exosome than in supernatant. qRT-PCR results showed that compared with the control group，The expression of circ PVT1 and circ 0014606 in serum exosomes in TNBC and NTNBC groups was significantly increased，and the expression was more significant in TNBC patients（P<0.05）. The expression level of circ PVT1 was correlated with tumor size，histological grade，TNM stage，pathological type and lymph node metastasis in TNBC patients（P<0.05）. The expression level of circ 0014606 was correlated with histological grade，TNM stage，pathological type and lymph node metastasis of TNBC patients（P<0.05）. Kaplan-Meier analysis showed that the 3-year disease-free survival rate of TNBC patients with high circ PVT1 expression was 46.3%，which was significantly lower than 71.2% in the group with low circ PVT1 expression（P<0.05）. The 3-year disease-free survival rate of TNBC patients in the circ 0014606 high expression group was 40.8%，significantly lower than 68.0% in the circ 0014606 low expression group（P<0.05）.

Serum exosome circ PVT1 and circ 0014606 are highly expressed in breast cancer，and are more significantly expressed in TNBC. They are closely related to the clinicopathology and prognosis of TNBC patients，and are expected to be a specific indicator for judging the malignancy of TNBC and poor prognosis.