ABSTRACT
@#Objective: To observe the expression of long-chain non-coding RNA (lncRNA) RP3-340N1.2 in breast cancer tissues and its effect on proliferation and migration of breast cancer MCF-7 cells, and to explore the possible mechanism. Methods: 13 pairs of breast cancer tissues and adjacent tissues from breast cancer patients, who underwent radical surgery at the Cancer Center of theAffiliated People’s Hospital of Hubei University of Medicine from Jan. 2017 to Sep. 2017, were collected for this study. qRT-PCR was used to detect the differential expression of RP3-340N1.2 in collected tissue samples and breast cancer cell lines and normal breast epithelial cell line. RP3-340N1.2 plasmid (experimental group) and the negative control plasmid (control group) were transfected into breast cancer MCF-7 cells using Lipofectamine 3000. Cell counting (CCK-8) and Transwell migration assay were used to examine the effect of RP3-340N1.2 over-expression on proliferation and migration of MCF7 cells, the effect of RP3-340N1.2 over-expression on the mRNA expression of miR-134-5p and OPCML was detected by qRT-PCR, and Western blotting was used to detect the expression of OPCML protein. Results: The expression of RP3-340N1.2 in breast cancer tissues was significantly lower than that in adjacent tissues ( P <0.01), and the expression of RP3-340N1.2 in breast cancer cell lines was significantly lower than that in normal breast epithelial cells ( P < 0.01). Up-regulation of RP3-340N1.2 decreased the proliferation and migration of MCF7 cells (all P <0.05). After over-expression of RP3-340N1.2 in MCF7 cells, the expression of miR-134-5p obviously decreased ( P <0.01); moreover, the mRNA and protein expressions of OPCML significantly increased ( P <0.01) while the expressions of cell cycle regulatory proteins (CDK4, Cyclin D2) and cell migration regulatory proteins (Vimentin and N-cadherin) decreased significantly (all P <0.01). Conclusion: RP3-340N1.2 is low expressed in breast cancer tissues and cell lines. Up-regulation of RP3-340N1.2 expression can lead to decreased expression of miR-1345p and increased expression of OPCML gene, thereby inhibiting the proliferation and migration of breast cancer cells.