High expression of LC3B is associated with progression and poor outcome in triple-negative breast cancer

Microtubule-associated protein 1 light chain 3B (LC3B) was involved in autophagosome formation and had been as a marker of autophagy which played an important role in the development of breast cancer. The purpose of this study was to explore the level of LC3B expression in four stages of triple-negative breast cancer (TNBC) and to evaluate the prognostic significance of LC3B expression in TNBC. The ultimate aim was to identify the new factor that could be useful in predicting clinical behavior of TNBC. We evaluated the expression level of LC3B protein in four kinds of TNBC tissue samples, including intraductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC) without metastases, IDC with lymph node metastases (LNM), and IDC with distant metastases (DM). Hundred and four primary TNBC patients were involved in present study, and the expression level of LC3B protein was assessed by immunohistochemistry. Medical records of these patients were reviewed, and the clinicopathological analysis was performed. High expression of LC3B was observed in 7.7 % of DCIS (1 of 13 cases), 16.2 % of IDC (6 of 37 cases), 35.7 % of LNM (15 of 42 cases), and 58.3 % of DM (7 of 12 cases). LC3B high expression was significantly associated with tumor size (P = 0.028), lymph node metastasis (P = 0.002), and Ki-67 expression (P = 0.047). LC3B high expression patients showed poorer DFS and OS rates compared with LC3B low expression patients (P = 0.024, and P = 0.047, respectively). Multivariate analyses confirmed that high LC3B expression was an independent and significant factor for predicting the poor outcome of TNBC patients. These preliminary results demonstrated that high LC3B expression was associated with lymph node and distant metastasis. Furthermore, high LC3B protein expression was correlated with shorter survival in patients with triple-negative breast carcinoma. These findings provided preliminary evidence for the function of LC3B on the progression of TNBC and suggested LC3B was a useful marker in prognostic evaluation for patients with TNBC.