Li Hong-li, Wang Tong-shan, Li Xiao-yu, Li Nan, Huang Ding-zhi, Chen Qi, Ba Yi
Department of Gastrointestinal Oncology, Tianjin Medical University Cancer Institute and Hospital, Tianjin 300060, China.
Chin Med J (Engl). 2007 May 20;120(10):905-9.
Uncontrolled cell division is one of the hallmarks of tumor growth. Researches have been focused on numerous molecules involved in this process. Cyclins are critical regulatory proteins of cell cycle progression and/or transcription. The present study aimed to investigate the anti-proliferative effect of cyclin L2, and to define its growth regulatory mechanisms using human lung adenocarcinoma cell line A549.
Human cyclin L2 was transfected into human lung adenocarcinoma cells (A549 cell), and was expressed in a mammalian expression vector pcDNA3.1. The effects and mechanisms of the cyclin L2 in cell growth, cell cycle analysis and apoptosis were studied by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), flow cytometry or Western blot, respectively.
Overexpression of cyclin L2 inhibited the growth of A549 cells. Cell cycle analysis in cells transfected with pCCNL2 revealed an increment in proportion in G0/G1 phase ((68.07 +/- 4.2)%) in contrast to (60.39 +/- 2.82)% of the cells transfected with mock vector. Apoptosis occurred in (7.25 +/- 0.98)% cells transfected with pCCNL2, as compared with (1.25 +/- 0.21)% of the mock vector control group. Cyclin L2-induced-G0/G1 arrest and apoptosis involved upregulation of caspase-3 and downregulation of Bcl-2 and survivin.
The results indicate that overexpression of cyclin L2 protein may promote efficient growth inhibition of human lung adenocarcinoma cells by inducing G0/G1 cell cycle arrest and apoptosis.
细胞分裂失控是肿瘤生长的标志之一。研究聚焦于参与这一过程的众多分子。细胞周期蛋白是细胞周期进程和/或转录的关键调节蛋白。本研究旨在探讨细胞周期蛋白L2的抗增殖作用，并利用人肺腺癌细胞系A549确定其生长调节机制。
将人细胞周期蛋白L2转染到人肺腺癌细胞（A549细胞）中，并在哺乳动物表达载体pcDNA3.1中表达。分别通过3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）、流式细胞术或蛋白质免疫印迹法研究细胞周期蛋白L2在细胞生长、细胞周期分析和凋亡中的作用及机制。
细胞周期蛋白L2的过表达抑制了A549细胞的生长。转染pCCNL2的细胞的细胞周期分析显示，G0/G1期比例增加（(68.07±4.2)%），而转染空载体的细胞为(60.39±2.82)%。转染pCCNL2的细胞中有(7.25±0.98)%发生凋亡，而空载体对照组为(1.25±0.21)%。细胞周期蛋白L2诱导的G0/G1期阻滞和凋亡涉及半胱天冬酶-3的上调以及Bcl-2和生存素的下调。
结果表明，细胞周期蛋白L2蛋白的过表达可能通过诱导G0/G1期细胞周期阻滞和凋亡来促进对人肺腺癌细胞的有效生长抑制。
