Yuan Li, Zhou Ping, Liu Wengang, Jiang Liqing, Xia Mengwen, Zhao Yongfeng
Department of Nuclear Medicine, The Third Xiangya Hospital of Central South University, Changsha, China.
Department of Ultrasound, The Third Xiangya Hospital of Central South University, Changsha, China.
Cytojournal. 2024 Nov 15;21:41. doi: 10.25259/Cytojournal_47_2024. eCollection 2024.
Thyroid cancer (TC) therapy, which is routinely used at present, can improve patients' survival rates. However, lymph node metastasis results in a higher degree of TC malignancy in patients who experience recurrence and/or death. The elucidation of new mechanisms of TC metastasis can help identify new therapeutic targets. Midkine (MDK) is expressed aberrantly in various cancers. However, the regulatory mechanisms of MDK in TC remain largely unknown. Hence, this study mainly explores the effect and molecular function of MDK in TC.
MDK gene expression and protein levels were analyzed using the Gene Expression Profiling Interactive Analysis and the Human Protein Atlas online databases. MDK messenger RNA (mRNA) in TC was analyzed by quantitative real-time polymerase chain reaction. MDK, phosphatidylinositol 3 kinase (PI3K), phosphorylated AKT (p-AKT), and phosphorylated mammalian target of rapamycin (p-mTOR) protein in TC were analyzed by Western blotting. Transwell and wound healing assays were performed to evaluate TC cell metastasis.
MDK mRNA was significantly highly expressed in most patients with TC ( 0.05). Moreover, MDK gene expression levels correlated with different TC stages. MDK protein was negative in normal tissues and positive in TC tissues. MDK mRNA and protein were significantly highly expressed in TC cells ( 0.01). Compared with metastasis in the control group, that in the MDK group is significantly suppressed by MDK knockdown ( < 0.001). MDK knockdown also significantly inhibited PI3K, p-AKT, and p-mTOR protein expression in TPC-1 and K1 cells ( 0.001). The activation of PAmT-P significantly enhanced the PI3K, p-AKT, and p-mTOR protein expression in TPC-1 and K1 cells ( 0.001) and promoted metastasis ( 0.001), thereby disrupting the inhibitory effect of the MDK knockdown.
Our findings confirmed that MDK promotes TC migration and invasion by activating PAmT-P. MDK is a novel molecular target for the treatment of patients with metastatic TC.
目前常规使用的甲状腺癌（TC）治疗方法可提高患者生存率。然而，淋巴结转移会导致复发和/或死亡患者的TC恶性程度更高。阐明TC转移的新机制有助于确定新的治疗靶点。中期因子（MDK）在多种癌症中异常表达。然而，MDK在TC中的调控机制仍 largely 未知。因此，本研究主要探讨MDK在TC中的作用及分子功能。
使用基因表达谱交互式分析和人类蛋白质图谱在线数据库分析MDK基因表达和蛋白质水平。通过定量实时聚合酶链反应分析TC中的MDK信使核糖核酸（mRNA）。通过蛋白质免疫印迹分析TC中的MDK、磷脂酰肌醇3激酶（PI3K）、磷酸化AKT（p-AKT）和磷酸化雷帕霉素靶蛋白（p-mTOR）蛋白。进行Transwell和伤口愈合试验以评估TC细胞转移。
大多数TC患者的MDK mRNA显著高表达（P<0.05）。此外，MDK基因表达水平与不同的TC分期相关。MDK蛋白在正常组织中为阴性，在TC组织中为阳性。MDK mRNA和蛋白在TC细胞中显著高表达（P<0.01）。与对照组的转移相比，MDK组的转移在MDK敲低后显著受到抑制（P<0.001）。MDK敲低还显著抑制了TPC-1和K1细胞中PI3K、p-AKT和p-mTOR蛋白表达（P<0.001）。PAmT-P的激活显著增强了TPC-1和K1细胞中PI3K、p-AKT和p-mTOR蛋白表达（P<0.001）并促进了转移（P<0.001），从而破坏了MDK敲低的抑制作用。
我们的研究结果证实MDK通过激活PAmT-P促进TC迁移和侵袭。MDK是转移性TC患者治疗的新分子靶点。
