Background: The imprinted gene dlk1 has been recognized as a cancer related gene since it aberrantly expressed in a series of cancer tissues, but its role in lung cancer is still unknown. The aim of this study is to examine dlk1's expression in non-small cell lung cancers (NSCLCs) and investigate the molecular mechanism by which dlk1 could accelerate the proliferation of the cells in lung cancer cell lines (H520).
Methods: The relative expression of dlk1 among 30 NSCLC specimens and their adjacent normal lung tissues were analyzed by RT-PCR. A cell model that stably expressed exogenous dlk1 was established following that the dlk1 gene was cloned into a eukaryotic expression vector and then transfected into the lung cancer cells H520. CCK8 analysis and colony forming assay were employed to investigate the effect of dlk1 on cell proliferation. The expression of CyclinB1 was detected by Western blot.
Results: dlk1 aberrantly expressed in 36.7% (11/30) of the tumor tissues of NSCLC compared with their adjacent cancer lung tissues. CCK8 analysis showed that overexpression of dlk1 could promote the proliferation of H520 cells (P < 0.05) and the results was further confirmed by colony forming assay. Western blot analysis found that over expression of dlk1 could up-regulate the expression of CyclinB1 (P < 0.05).
Conclusions: dlk1 aberrantly expressed in NSCLCs. The Overexpression of dlk1 could accelerate the proliferation of lung cancer cells H520 in vitro, probably through up-regulating the expression of cell cycle protein CyclinB1.
背景与目的: 印记基因dlk1因在多种肿瘤组织中出现异常表达而受到研究者越来越多的关注，但dlk1基因与肺癌的关系尚无报道。本研究首先在肺癌组织中检测了dlk1基因的表达，并进一步利用肺癌细胞系H520对dlk1基因促进细胞增殖的分子机制进行了初步研究。
方法: 首先，采用RT-PCR在30对非小细胞肺癌肿瘤及其配对癌旁组织中检测dlk1基因的表达。然后，克隆人源dlk1基因，转染并筛选出稳定表达dlk1基因的肺癌细胞。最后，利用CCK8法研究dlk1基因对细胞增殖能力的影响，并用Western blot技术分析细胞周期蛋白CyclinB1的表达。
结果: RTPCR结果显示，dlk1基因在36.7%的非小细胞肺癌肿瘤组织中表达水平高于癌旁肺组织。在成功获得了稳定表达外源性dlk1基因的肺癌细胞H520-dlk1的基础上，CCK8实验及平板集落实验显示，稳定转染dlk1可以明显促进肺鳞癌细胞H520的增殖能力（P < 0.05）。同时，稳定表达DLK1蛋白可以上调细胞周期蛋白CyclinB1的表达水平（P < 0.05）。
结论: dlk1在非小细胞肺癌中存在异常高表达，它可以通过上调细胞周期蛋白CyclinB1的表达，促进肺鳞癌细胞H520的增殖。提示dlk1基因的异常表达可能在肺癌的发生演进中发挥作用。