Long non-coding RNA BANCR indicates poor prognosis for breast cancer and promotes cell proliferation and invasion

Abstract

Objective: We investigated the expression of human long non-coding ribonucleic acid (lncRNA), BRAF-activated non-coding RNA (BANCR) in breast cancer tissues and its effects on the in vitro proliferation, apoptosis, invasion and metastasis of breast cancer cells; also, we investigated its possible mechanism.

Patients and methods: The expressions of BANCR in 65 pairs of breast cancer tissues and para-carcinoma normal breast tissues were detected by Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR). The expressions of BANCR in normal breast epithelial cells (MCF10A) and breast cancer cells (MCF-7, MDA-MB-231, SKBR3 and BT-20) were further detected. The knockdown efficiency of BANCR small interfering RNA (siRNA) in MCF-7 cells was detected by qRT-PCR. The effects of BANCR knockdown on proliferation, apoptosis, invasion and metastasis capacities of MCF-7 cells were explored via methyl thiazolyl tetrazolium (MTT) proliferation assay, cell colony formation assay, fluorescence-activated cell sorting (FACS) and transwell migration assay. Western blotting was used to detect the changes in expressions of apoptosis-related proteins, epithelial-mesenchymal transition (EMT)-related proteins and matrix metalloproteinases (MMPs) after knockdown of BANCR.

Results: The expression level of lncRNA BANCR in breast cancer tissues was significantly higher than that in para-carcinoma normal tissues. The prognosis of patients in low-expression BANCR group was significantly superior to that of patients in high-expression BANCR group. After BANCR knockdown in breast cancer MCF-7 cells, the cell proliferation and colony formation capacities were significantly inhibited. Further mechanism research showed that inhibiting BANCR could promote the apoptosis of MCF-7 cells. Results of Western blotting revealed that the expressions of B-cell lymphoma 2 associated X protein (BAX), cleaved-Caspase-3 and cleaved-poly adenosine diphosphate-ribose polymerase (PARP) in knockdown group were significantly up-regulated compared with those in control group. Both wound-healing assay and transwell migration assay showed that the down-regulation of lncRNA BANCR could inhibit the invasion and metastasis capacities of MCF-7 cells, whose mechanism was related to the inhibition of EMT process and down-regulation of MMP expressions in cells.

Conclusions: LncRNA BANCR is highly expressed in breast cancer, which is significantly correlated with the prognosis of patients; moreover, it can promote the growth, invasion and metastasis of ovarian cancer cells. The down-regulation of BANCR can inhibit the proliferation, invasion and metastasis capacities of MCF-7 cells.