LncRNA AL133467. 1 Acts as the ceRNA of miR-661 to Inhibit theProliferation and Invasion of Breast Cancer Cells / 中国生物化学与分子生物学报

ABSTRACT

Long non-coding RNAs (LncRNAs) are abnormally expressed in a variety of tumors and participate in the occurrence and development of tumors. However, the expression and function of many LncRNAs in tumors have not been fully clarified. In this paper, 113 normal breast tissues and 1 109breast cancer tissues were analyzed in TCGT database. LncRNA AL133467. 1 was found to be lowly expressed in breast cancer tissues and negatively correlated with poor prognosis of breast cancer patients. The expression of AL133467. 1 in breast cancer cells was significantly lower than that in normal breast epithelial cells. We overexpressed AL133467. 1 in relatively low-expression breast cancer cells SKBR3and BT474, and cell count and plate colony-formation experiments showed that overexpression ofAL133467. 1 could significantly inhibit the proliferation and colony formation of breast cancer cells (P< 0. 01). Cell scratch and Transwell assays showed that the migration and invasion ability of breast cancer cells overexpressing AL133467. 1 was significantly reduced compared with the control group (P<0. 01). MiRDB database showed that AL133467. 1 had binding sites with miR-661. miR-661 could bind the transducer of ErbB2, 2 (ErbB2, 2, TOB2). qRT-PCR showed that miR-661 was highly expressed inbreast cancer cells and positively correlated with poor prognosis of breast cancer patients (P < 0. 001). Luciferase reporter assays showed that AL133467. 1 had specific binding to miR-661 (P < 0. 01). AL133467. 1 overexpression could inhibit the expression of miR-661 in breast cancer cells (P<0. 0001). Transfection of miR-661 mimics eliminated the inhibitory effect of overexpression of AL133467. 1 on breast cancer cells (P < 0. 001). In addition, qRT-PCR and Western blotting results showed that overexpression of AL133467. 1 up-regulated TOB2 mRNA (P < 0. 0001) and protein levels. But whenmiR-661 mimics were transfected, TOB2 mRNA (P < 0. 0001) and protein levels were significantly inhibited. In conclusion, as a competitive endogenous RNA of miR-661. AL133467. 1 promotes the expression of TOB2, thereby inhibiting the proliferation and invasion of breast cancer cells.