Role and clinicopathological significance of STAT3 protein in triple-negative breast cancer

ObjectiveTo investigate the expression of STAT3 in triple-negative breast cancer(TNBC) tissue, analyze its significance as a molecular marker for targeted therapy to TNBC patients, and explore the pathogenesis, clinical efficacy and prognosis of TNBC.

MethodsThe expression of STAT3 gene in TNBC was detected by immunohistochemistry, and its relationship with clinicopathological features was analyzed.The STAT3-shRNA expression vector was constructed to establish a TNBC cell line(MDA-MB-231) with down-regulated STAT3 gene expression.The differences in cell proliferation, invasion and migration abilities before and after transfection were analyzed by CCK-8 and Transwell assay.

ResultsThe expression of STAT3 protein in TNBC tissue was significantly higher than that in breast tissue(P < 0.01), and the positive expression rate of STAT3 in TNBC was positively correlated with tumor volume, histological grade, TNM stage and lymph node metastasis(P < 0.05 to P < 0.01).Compared with the negative control group and blank control group, the expression of STAT3 protein in the experimental group was significantly decreased after transfection in MDA-MB-231 cells, the cell proliferation activity in the experimental group decreased slowly, and the number of cells passing through the basement membrane in the experimental group was significantly reduced(P < 0.01).

ConclusionsThe STAT3-shRNA expression vector effectively down-regulates the expression of STAT3 gene in TNBC by RNA interference.Targeting STAT3-shRNA can inhibit the proliferation, invasion and migration and pro-apoptotic ability of MDA-MB-231 cells.