Men Li-Jie, Liu Ji-Zhu, Chen Hai-Ying, Zhang Li, Chen Shuang-Feng, Xiao Tai-Wu, Wang Jing-Xia, Li Guang-Yao, Wu Ya-Ping
1Department of Hematology, Liaocheng People's Hospital and Clinical School of Taishan Medical University, Liaocheng, 252000 Shandong Province P. R. China.
Zhong Yuan Academy of Biological Medicine, Liaocheng University, Liaocheng People's Hospital, Medical School of Liaocheng, Liaocheng, 252000 Shandong Province P. R. China.
Cancer Cell Int. 2018 Jan 29;18:13. doi: 10.1186/s12935-018-0507-1. eCollection 2018.
G protein-coupled receptors (GPR) are involved in a wide range of physiological processes, some of which, however, can be hijacked by tumor cells. Over-expression of G protein-coupled receptors 137 (GPR137) are associated with the growth of tumor cells, but under-expression of GPR137 has shown to inhibit cell proliferation in several different types of cancers. Currently, the role of GPR137 in leukemia is still unclear. In this study, the effect of under-expression of GPR137 on inhibiting the proliferation of leukemia cells is explored, to identify a novel target for leukemia treatment.
In this study, lentivirus-mediated RNA interference (RNAi) was employed to investigate the role of GPR137 in two leukemia cell lines K562 and HL60. The gene expression of GPR137 was analyzed by RT-PCR and its protein expression was determined by Western blot. Flow cytometry and Annexin V/7-AAD Apoptosis Detection Kit was used respectively in cell cycle and apoptosis analysis. The protein expression of CyclinD1, CDK4, BCL-2 and caspase-3 were also determined.
There was high level of constitutive expression of GPR137 in leukemia cancer cell lines K562 and HL60. Lentivirus-mediated RNAi could significantly down-regulate gene and protein expression of GPR137 in both cell lines. Down regulation of GPR137 was associated with the reduction in proliferation rate and colony forming capacity. In addition, down regulation of GPR137 arrested cells in the G0/G1 phase of cell cycle and induced apoptosis in both leukemia cell lines K562 and HL60.
The expression of GPR137 is associated with the proliferation of leukemia cell lines. Down regulation of GPR137 could inhibit proliferation and promote apoptosis in leukemia cells, which makes it a promising bio-marker and therapeutic target to treat patients with leukemia.
G蛋白偶联受体（GPR）参与多种生理过程，然而其中一些过程可能被肿瘤细胞利用。G蛋白偶联受体137（GPR137）的过表达与肿瘤细胞的生长相关，但GPR137的低表达已显示在几种不同类型的癌症中可抑制细胞增殖。目前，GPR137在白血病中的作用仍不清楚。在本研究中，探讨GPR137低表达对白血病细胞增殖的抑制作用，以确定白血病治疗的新靶点。
在本研究中，采用慢病毒介导的RNA干扰（RNAi）来研究GPR137在两种白血病细胞系K562和HL60中的作用。通过RT-PCR分析GPR137的基因表达，并通过蛋白质印迹法测定其蛋白表达。分别使用流式细胞术和Annexin V/7-AAD凋亡检测试剂盒进行细胞周期和凋亡分析。还测定了细胞周期蛋白D1、细胞周期蛋白依赖性激酶4、B细胞淋巴瘤-2（BCL-2）和半胱天冬酶-3的蛋白表达。
白血病癌细胞系K562和HL60中存在高水平的GPR137组成性表达。慢病毒介导的RNAi可显著下调两种细胞系中GPR137的基因和蛋白表达。GPR137的下调与增殖率和集落形成能力的降低相关。此外，GPR137的下调使细胞停滞在细胞周期的G0/G1期，并诱导白血病细胞系K562和HL60凋亡。
GPR137的表达与白血病细胞系的增殖相关。GPR137的下调可抑制白血病细胞的增殖并促进其凋亡，这使其成为治疗白血病患者的有前景的生物标志物和治疗靶点。
