ABSTRACT
Objective:To investigate the clinical significance of MAPT-IT1 in breast cancer and its biological effect in vitro.Methods:The expression of MAPT-IT1 in breast cancer was analyzed by TCGA database. 64 cases of breast cancer and normal adjacent tissues were collected. Human breast cancer MDA-MB-231 and MCF-7 cells were cultured and overexpressed MAPT-IT1 or rescue miR-181a-5p by cell transfection. MDA-MB-231 cells were divided into blank group A, overexpression group A and recovery group A; MCF-7 cells were divided into blank group B, overexpression group B and recovery group B. Real time quantitative PCR (RT-qPCR) was used to detect the expression of MAPT-IT1, miR-181a-5p and MAPT mRNA. Western blot was used to detect the expression of MAPT protein. CCK-8 assay was used to detect cell proliferation, and Transwell invasion assay was used to detect cell invasion.Results:The expression of MAPT-IT1 in normal paracancerous tissues and breast cancer tissues was 0.011±0.002 and 0.028±0.003 respectively. The expressions of MAPT-IT1 in breast cancer tissues were significantly higher than those in adjacent normal tissues, and high expression of MAPT-IT1 was correlated with early tumor progression, ER positive and prolonged prognosis ( P<0.05) . In blank group A, overexpression group A and recovery group A, the expressions of MAPT-IT1 were 1.000±0.078, 8.597±0.320 and 8.540±0.177, miR-181a-5p were 1.000±0.027, 0.263±0.024, 4.433±0.239, MAPT were 1.000±0.071, 3.297±0.243, 0.497±0.029. In blank group B, overexpression group B and recovery group B, the expressions of MAPT-IT1 were 1.000± 0.081, 5.716±0.309, 5.288±0.176, miR-181a-5p were 1.000±0.024, 0.291±0.022, 3.648±0.073, and MAPT were 1.000±0.054, 3.309±0.177, 0.883±0.075. After overexpression of MAPT-IT1, the expression of miR-181a-5p was down-regulated, while the expression of MAPT was significantly increased ( P<0.001) , and the proliferation and invasion ability of MDA-MB-231 and MCF-7 cells were significantly decreased ( P<0.05) . Re-expression of miR-181a-5p down-regulated MAPT and promoted cell proliferation and invasion ( P<0.05) . Conclusion:Overexpression of MAPT-IT1 can significantly down-regulate the expression of miR-181a-5p and enhance MAPT and inhibit the malignant phenotype of breast cancer cells in vitro.
ABSTRACT
Abstract Objectives Accumulating research have reported that microRNAs (miRNAs) play important roles in Retinoblastoma (RB). Nonetheless, the function and underlying mechanism of miR-181a-5p in RB remain ambiguous. Methods The relative expression levels of miR-181a-5p and NRAS mRNA were detected by quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR). RB cell proliferation was measured using the Cell Counting Kit-8 (CCK-8) and 5′-Bromo-2′-deoxyuridine (BrdU) assays. Transwell assays and flow cytometry were performed to detect the migration, invasion, and apoptosis of RB cells. The interaction between miR-181a-5p and NRAS was explored using luciferase experiments, western blotting, and qRT-PCR. Results miR-181a-5p expression was found to be decreased in RB tissues and cell lines, and its expression was correlated with unfavorable pathological features of the patients. In vitro experiments revealed that miR-181a-5p reduced RB cell proliferation, migration, and invasion while enhancing apoptosis. Further research confirmed that NRAS is a direct target of miR-181a-5p. miR-181a-5p inhibited NRAS expression at both the mRNA and protein levels. Co-transfection of pcDNA-NRAS or NRAS small interfering RNA (siRNA) reversed the effects of miR-181a-5p mimics or miR-181a-5p inhibitors on RB cells. Conclusion miR-181a-5p was significantly downregulated during the development of RB, and it suppressed the malignant behaviors of RB cells by targeting NRAS.