Expression of synuclein gamma indicates poor prognosis of triple-negative breast cancer

Synuclein gamma (SNCG), previously identified as breast cancer–specific gene 1, is highly expressed in malignant cells but not in normal epithelium. Studies have demonstrated that the expression of SNCG is an independent predictive marker for recurrence and metastasis in breast cancer. Triple-negative breast cancer (TNBC) is characterized by a lack of expression of both the estrogen receptor and progesterone receptor proteins as well as HER-2 and is often associated with particularly poor outcomes, early development of chemotherapy resistance, and ineffectiveness of targeted therapy. This study aimed to reveal whether SNCG-positive TNBC is more likely than SNCG-negative TNBC to have a more aggressive phenotype. One hundred and two TNBC patients were divided into two groups according to the SNCG protein expression. Clinical and biological features of SNCG-positive tumors were compared with SNCG-negative tumors. Association between survival and SNCG expression was analyzed by the Kaplan–Meier method. Hazard ratios and 95 % confidence intervals (CIs) were calculated using Cox regression. And 34.3 % TNBCs showed moderate to strong positive SNCG expression. Patients whose tumors expressed SNCG had significantly shorter disease-free survival (P = 0.013) and a higher probability of death (P = 0.002) when compared with those whose tumors did not express SNCG. The hazard ratio of metastasis or recurrence based on SNCG expression status was 2.800 (95 % CI 1.193–6.574; P = 0. 018). There was no significant correlation between SNCG expression and age, lymph node involvement, and tumor stage histological type, except tumor size which was significantly associated with SNCG expression (P = 0.032, R = 0.212). This study suggests that SNCG expression indicates 〈correlates with?〉 a much poorer prognosis of TNBC. SNCG is expected to be a useful marker for TNBC progression and a potential target for TNBC treatment.