Background: Delta-Like1 (DLL1) can combine with Notch receptor and activate the Notch signal pathway, then made a decision to cell differentiation and regulate the development of many tissues. It is proved that DLL1 was highly correlated with tumor'growth and differentiation, our previously study showed that DLL1 was associated with MDR in small cell lung cancer (SCLC). The aim of this study is to furtherly investigate the role of DLL1 gene in small cell lung multi-drug resistance.
Methods: Firstly, the analysis of qRT-PCR and Western blot were used to study differential expression of DLL1 from mRNA and protein levels in both the H69 and H69AR cell lines. Then, we developed a stably DDL1 overexpressing H69AR-eGFP-DLL1 subline, by transfection with DLL1-pIRES2-EGFP. Moreover, the sensitivities of cells to chemotherapy drugs such as ADM, DDP, VP-16 were detected by CCK8 assay. The change of cell cycle and apoptosis rate were detected by flow cytometry.
Results: The expression of DLL1 was significantly decreased in H69AR cells than that in the H69 cells. The sensitivities of H69AR cells to chemotherapy drugs were increased when up-regulated the expression of DLL1, enforced DLL1 expression increased cell apoptosis and the cell cycle arrest in G0/G1 and S phase in H69AR cells, the expression of downstream genes HES1 and HEY1 were increased after transfected with DLL1-pIRES2-EGFP.
Conclusions: Our results suggest that overexpression of DLL1 in small cell lung cancer may increase the sensitivity of cells to chemotherapeutic agents. DLL1 influence drug resistance of small cell lung cancer through activating transcription of downstream genes HES1 and HEY1.
背景与目的 DLL1（Delta-Like1）与Notch受体结合激活Notch信号通路，从而决定细胞的分化，并调控多种组织的生长发育。已有研究报道DLL1与肿瘤的生长、分化密切相关。前期基因芯片发现DLL1与小细胞肺癌的耐药性相关，本研究旨在进一步探讨DLL1在小细胞肺癌多药耐药中的作用。方法 首先通过QRT-PCR和Western blot从基因和蛋白水平检测化疗敏感细胞株H69及多药耐药细胞株H69AR中DLL1的差异表达；转染DLL1-pIRES2-EGFP表达质粒上调H69AR细胞中的DLL1的表达，构建稳定转染的过表达细胞株H69AR-eGFP-DLL1 ，通过CCK8检测细胞对各种化疗药物（ADM, DDP, VP-16）的敏感性变化，流式细胞仪检测细胞周期及凋亡的变化。结果 DLL1在化疗敏感细胞H69中的表达明显高于H69AR，过表达H69AR中DLL1的表达能够增加细胞对化疗药物的敏感性，促进细胞的凋亡，细胞周期发生G0/G1期及S期阻滞，上调DLL1增加其下游基因HES1、HEY1的表达。结论 在小细胞肺癌中上调DLL1的表达可能增加细胞对化疗药物的敏感性，DLL1通过肿瘤细胞间的相互作用激活HES1、HEY1等下游基因，影响小细胞肺癌的多药耐药。