miR-218-5p Targeting TPX2 Regulates p53 Pathway and Inhibits Malignant Progression of Lung Adenocarcinoma / 中国肺癌杂志

BACKGROUND@#Lung adenocarcinoma (LUAD) is a major subtype of lung cancer, and its treatment and diagnosis remain a hot research topic. Targeting protein for Xenopus kinesin-like protein 2 (TPX2) is highly expressed in a variety of cancer cells and may be associated with the progression of LUAD. This study aimed to investigate the effect of TPX2 on the malignant progression of LUAD cells and the regulatory mechanisms.@*METHODS@#The expression of gene TPX2 in LUAD tissues from The Cancer Genome Atlas (TCGA) database was analyzed by bioinformatics analysis techniques. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of TPX2 and miR-218-5p in human lung normal cell lines and human LUAD cell lines. Western blot was used to detect TPX2 protein expression in cell lines and its effect on the expression of key proteins in the p53 signaling pathway. The relationship between TPX2 and miR-218-5p was predicted using bioinformatics and verified by dual luciferase reporter gene assay. Cell counting kit-8 (CCK-8) assay, cell clone formation, cell scratching, Transwell assay, and flow cytometry were used to detect the effects of miR-218-5p and TPX2 on LUAD cell function.@*RESULTS@#TPX2 was significantly overexpressed in LUAD cells, and knockdown of TPX2 inhibited LUAD cell proliferation, migration, and invasion, promoted apoptosis and induced G2/M phase block, and promoted the expression of key proteins in the p53 signaling pathway. miR-218-5p, an upstream regulator of TPX2, could inhibit its expression. Overexpression of miR-218-5p eliminated the malignant development caused by high expression of TPX2, inhibited the malignant processes of LUAD cells such as proliferation and migration as well as promoted the p53 signaling pathway.@*CONCLUSIONS@#miR-218-5p targets and inhibits TPX2 expression and exerts an inhibitory effect on the malignant progression of LUAD cells via p53.

MiR-218-5p Promotes Rotenone-induced Apoptosis of Gastric Cancer Cells by Inhibiting TDP1 Expression / 肿瘤防治研究

Objective To investigate the effect of overexpression of miR-218-5p and inhibition of TDP1 expression on rotenone-induced apoptosis of gastric cancer cells, and to elucidate its possible mechanism. Methods The expression levels of miR-218-5p and TDP1 in human normal gastric epithelial cells and four gastric cancer cells were detected by RT-PCR, and their correlation was analyzed. The targeting regulation of miR-218-5p on TDP1 was verified by dual luciferase reporter gene assay. Gastric cancer cell injury model was induced by 1.0 μmol/L rotenone. Cell cycle and apoptotic rate were detected by flow cytometry. TDP1 level in mitochondria and the expression of Bax and Cyt-c protein were detected by Western blot. Results The expression of miR-218-5p was low in gastric cancer cells (P < 0.05), and TDP1 was high (P < 0.01). There was a negative correlation between the expression of miR-218-5p and TDP1 (R2=0.9580, P=0.0212). Compared with the control group, SGC-7901 cells in the injured group developed G1 phase arrest and the apoptotic rate increased (P < 0.01). After transfection of miR-218-5p-mimic, the cell arrest and apoptotic rate further increased (P < 0.01), the expression of Bax and Cyt-c increased (P < 0.01), while the level of TDP1 in mitochondria decreased (P < 0.01). The G1 phase arrest of cells in TDP1 overexpression group was relieved, the apoptotic rate was decreased (P < 0.01), the level of TDP1 in mitochondria was increased (P < 0.01), and Bax and Cyt-c expression were decreased (P < 0.01). Conclusion MiR-218-5p can target TDP1 expression and induce apoptosis of gastric cancer cells. Its mechanism may be related to inhibiting mitochondrial DNA damage repair and function maintenance and activating mitochondrial endogenous apoptosis pathway.

MiR-218-5p Suppresses the Killing Effect of Natural Killer Cell to Lung Adenocarcinoma by Targeting SHMT1

PURPOSE: Lung adenocarcinoma (LA) is one of the major types of lung cancer. MicroRNAs (miRNAs) play an essential role in regulating responses of natural killer (NK) cells to cancer malignancy. However, the mechanism of miR-218-5p involved in the killing effect of NK cells to LA cells remains poorly understood. MATERIALS AND METHODS: The expression of miR-218-5p was examined by quantitative real-time polymerase chain reaction (qRT-PCR). Serine hydroxymethyl transferase 1 (SHMT1) level was detected by qRT-PCR or western blots. Cytokines production of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) were detected by ELISA. The killing effect of NK cells to LA cells was investigated using lactate dehydrogenase cytotoxicity assay kit. The interaction of miR-218-5p and SHMT1 was probed by luciferase activity assay. Xenograft model was established to investigate the killing effect of NK cells in vivo. RESULTS: miR-218-5p was enhanced and SHMT1 was inhibited in NK cells of LA patients, whereas stimulation of interleukin-2 (IL-2) reversed their abundances. Addition of miR-218-5p reduced IL-2-induced cytokines expression and cytotoxicity in NK-92 against LA cells. Moreover, SHMT1 was negatively regulated by miR-218-5p and attenuated miR-218-5p-mediated effect on cytotoxicity, IFN-γ and TNF-α secretion in IL-2-activated NK cells. In addition, miR-218-5p exhaustion inhibited tumor growth by promoting killing effect of NK cells. CONCLUSION: miR-218-5p suppresses the killing effect of NK cells to LA cells by targeting SHMT1, providing a potential target for LA treatment by ameliorating NK cells function.