Unregulated long non-coding RNA-AK058003 promotes the proliferation, invasion and metastasis of breast cancer by regulating the expression levels of the γ-synuclein gene

Abstract

The aim of the present study was to investigate the function of long chain non-coding RNA (lncRNA) in breast cancer cells. Quantitative polymerase chain reaction was used to measure mRNA expression levels in breast cancer tissues, adjacent tissues and in MCF-7 breast cancer cells. Western blot analysis was used to determine the protein expression levels. In addition, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was employed to measure the rates of cell proliferation. The invasion and migration of the MCF-7 cells were examined using a Transwell® assay. The expression levels of lncRNA-AK058003 were increased significantly in the breast cancer tissues and were found to strongly correlate with the severity of the breast cancer clinical stage. Bioinformatics analysis revealed that the γ-synuclein gene (SNCG) may be a target gene regulated by lncRNA-AK058003. Thus, lncRNA-AK058803 was downregulated using small interfering RNA, and the mRNA and protein expression levels of SNCG were shown to be significantly reduced. Furthermore, the proliferation, invasion and migration rates of the MCF-7 breast cancer cells were significantly reduced. Therefore, the results demonstrated that unregulated lncRNA-AK058003 in breast cancer cells promotes cancer cell proliferation, invasion and metastasis via the regulation of SNCG expression.

Keywords: breast cancer; long non-coding RNA-AK058003; small-interfering RNA; γ-synuclein gene.

Figure 1.

Relative expression levels of (A) long non-coding RNA-AK058003 and (B) SNCG mRNA in breast cancer tissues. Data are expressed as the mean ± standard deviation. *P<0.05, vs. control group; **P<0.05, vs. N1 group; ***P<0.05, vs. well-differentiated group. SNCG, γ-synuclein gene; N1, lymph node metastasis group; N0, lymph node non-metastasis group; well, well-differentiated group; moderate, moderately-differentiated group; poor, poorly-differentiated group.

Figure 2.

Expression levels of (A) long non-coding RNA-AK058003, (B) SNCG mRNA and (C) SNCG protein in MCF-7 cells at 48 h after treatment with siRNA-AK058003. Expression levels of mRNA were determined using quantitative polymerase chain reaction, while protein expression levels were measured using western blot analysis. Data are expressed as the mean ± standard deviation. *P<0.05, vs. NC or mock groups. SNCG, γ-synuclein gene; NC, negative control group; siRNA, small interfering RNA.

Figure 3.

Proliferation curves of MCF-7 cells in the control, mock, NC and siRNA-AK058003 groups, as determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and measuring the OD at 490 nm. Data are expressed as the mean ± standard deviation. *P<0.05, vs. control, NC or mock groups. NC, negative control group; OD, optical density; siRNA, small interfering RNA.

Figure 4.

Migration and invasion ability of MCF-7 cells in the control, mock, NC and siRNA-AK058003 groups, as determined by a Transwell® assay. (A) Microscopic observation of MCF-7 cells (Giemsa stain; magnification, ×200). (B) Quantification of MCF-7 cells passing through the membrane. Data are expressed as the mean ± standard deviation. *P<0.05, vs. control, NC or mock groups. NC, negative control group; siRNA, small interfering RNA.