Up to accomplishment of this study, the role of long non-coding RNAs (lncRNAs) in breast cancer has been investigated in several researches. Nevertheless, its association with the chemosensitivity of cancer was little known. Therefore, this study is focused on lncRNA GAS5 and its influence in the chemosensitivity of triple-negative breast cancer (TNBC).Expression of GAS5 in TNBC tissues and cells was detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and its methylation was evaluated using methylationspecific polymerase chain reaction (MSP). Moreover, in order to define the contributory role of GAS5 in TNBC, GAS5 expression, proliferation, and apoptosis of TNBC cells were detected by a series of experiment. Finally, the effects of GAS5 in vivo were investigated by measuring tumor formation in nude mice.GAS5 was poorly expressed in TNBC tissues and cells, which could regulate the progression of TNBC. The methylation of CpG island in the promoter region of GAS5 in MDA-MB-231 and MDA-MB-468 cells was decreased, while GAS5 expression in cells was increased. Overexpressed GAS5 reduced the inhibitory concentration (IC50) value and the cell proliferation of TNBC, and promoted their apoptosis, so as to delay the progression of TNBC.Our study provides evidence that up-regulated GAS5 suppressed the progression of TNBC and promoted chemosensitivity and apoptosis of TNBC cells. Thus, GAS5 may be a potential candidate for the treatment of TNBC.

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Whether the expression status of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2) receptor and Ki-67 show concordance between the primary tumors and the synchronous axillary lymph node (ALN) metastases has been discussed in numerous studies. However, to date, the results of these studies remain controversial. Therefore, the present study aimed to investigate whether the expression of ER, PR, HER-2 and Ki-67 was in concordance between the primary tumors and synchronous ALN metastases in patients with operable breast cancer (BC). A total of 60 tissue samples were collected from patients with primary operable BC diagnosed with primary tumors and synchronous ALN metastases. The expression levels of the four biomarkers, ER, PR, HER-2 and Ki-67, were assessed in primary lesions and synchronous ALN metastases samples using immunohistochemistry. The cutoff values were set to 10% for ER and PR, while the labeling index of Ki-67 was set to 14%. The immunostaining intensity of ER and PR was scored as negative (-), 1+, 2+ and 3+. The criteria for HER-2 testing in BC were implemented according to the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) guidelines. The concordance rates for ER, PR and HER-2 were 96.7 (58/60), 96.7 (58/60) and 90% (54/60), respectively. In addition, the kappa values of consistency in the primary lesions and the synchronous ALN metastases were 0.773 for ER, 0.654 for PR and 0.785 for HER-2. Furthermore, the P-values of ER, PR and Ki-67 numerical variables between the two groups were 0.393, 0.400 and 0.331, respectively, as demonstrated using a non-parametric Wilcoxon signed rank test. The findings of the present study demonstrated a high degree of concordance between the expression of ER, PR, HER-2 and Ki-67 in the primary tumors and that in the synchronous ALN metastases, suggesting that the BC primary tumor biomarkers may be used for the prognosis of synchronous ALN metastases in patients with operable BC.