Attar-Schneider Oshrat, Drucker Liat, Gottfried Maya
Lung Cancer Research Laboratory, Lung Cancer Unit, Meir Medical Center, Kfar Saba, Israel.
Oncogenetic Laboratory, Meir Medical Center, Kfar Saba, Israel.
Lab Invest. 2016 Sep;96(9):1004-15. doi: 10.1038/labinvest.2016.77. Epub 2016 Aug 8.
Metastasis underlies cancer morbidity and accounts for disease progression and significant death rates generally and in non-small cell lung cancer (NSCLC) particularly. Therefore, it is critically important to understand the molecular events that regulate metastasis. Accumulating data portray a central role for protein synthesis, particularly translation initiation (TI) factors eIF4E and eIF4G in tumorigenesis and patients' survival. We have published that eIF4E/eIF4GI activities and consequently NSCLC cell migration are modulated by bone-marrow mesenchymal stem cell secretomes, suggesting a role for TI in metastasis. Here, we aimed to expand our understanding of the TI factors significance to NSCLC characteristics, particularly epithelial-to-mesenchymal transition (EMT) and migration, supportive of metastasis. In a model of NSCLC cell lines (H1299, H460), we inhibited eIF4E/eIF4GI's expressions (siRNA, ribavirin) and assessed NSCLC cell lines' migration (scratch), differentiation (EMT, immunoblotting), and expression of select microRNAs (qPCR). Initially, we determined an overexpression of several TI factors (eIF4E, eIF4GI, eIF4B, and DHX29) and their respective targets in NSCLC compared with normal lung samples (70-350%↑, P<0.05). Knockdown (KD) of eIF4E/eIF4GI in NSCLC cell lines (70%↓, P<0.05) also manifested in decreased target levels (ERα, SMAD5, NFkB, CyclinD1, c-MYC, and HIF1α) (20-50%↓, P<0.05). eIF4E/eIF4GI KD also attenuated cell migration (60-75%↓, P<0.05), EMT promoters (15-90%↓, P<0.05), and enhanced EMT suppressors (30-380%↑, P<0.05). The importance of eIF4E KD to NSCLC phenotype was further corroborated with its inhibitor, ribavirin. Changes in expression of essential microRNAs implicated in NSCLC cell migration concluded the study (20-100%, P<0.05). In summary, targeting eIF4E/eIF4GI reduces migration and EMT, both essential for metastasis, thereby underscoring the potential of TI targeting in NSCLC therapy, especially the already clinically employed agents (ribavirin/4EGI). Comparison of these findings with previously reported effects of eIF4E/eIF4GI KD in multiple myeloma suggests a collective role for these TI factors in cancer progression.
转移是癌症发病的基础，通常导致疾病进展和显著的死亡率，在非小细胞肺癌（NSCLC）中尤为如此。因此，了解调节转移的分子事件至关重要。越来越多的数据表明蛋白质合成，特别是翻译起始（TI）因子eIF4E和eIF4G在肿瘤发生和患者生存中起核心作用。我们已经发表文章指出，骨髓间充质干细胞分泌产物可调节eIF4E/eIF4GI的活性，进而影响NSCLC细胞的迁移，这表明TI在转移过程中发挥作用。在此，我们旨在进一步了解TI因子对NSCLC特征的重要性，特别是对上皮-间质转化（EMT）和迁移的影响，这些过程对转移具有支持作用。在NSCLC细胞系（H1299、H460）模型中，我们抑制eIF4E/eIF4GI的表达（siRNA、利巴韦林），并评估NSCLC细胞系的迁移（划痕实验）、分化（EMT，免疫印迹）以及特定微小RNA的表达（qPCR）。最初，我们确定与正常肺组织样本相比，几种TI因子（eIF4E、eIF4GI、eIF4B和DHX29）及其各自的靶标在NSCLC中存在过表达（升高70 - 350%，P<0.05）。在NSCLC细胞系中敲低（KD）eIF4E/eIF4GI（降低70%，P<0.05）也导致靶标水平降低（ERα、SMAD5、NFkB、CyclinD1、c-MYC和HIF1α）（降低20 - 50%，P<0.05）。eIF4E/eIF4GI KD还减弱了细胞迁移（降低60 - 75%，P<0.05）、EMT促进因子（降低15 - 90%，P<0.05），并增强了EMT抑制因子（升高30 - 380%，P<0.05）。利巴韦林作为eIF4E的抑制剂，进一步证实了eIF4E KD对NSCLC表型的重要性。与NSCLC细胞迁移相关的关键微小RNA表达的变化为该研究画上句号（变化20 - 100%，P<0.05）。总之，靶向eIF4E/eIF4GI可减少迁移和EMT，而这两者都是转移所必需的，从而突出了TI靶向在NSCLC治疗中的潜力，特别是那些已经在临床上使用的药物（利巴韦林/4EGI）。将这些发现与先前报道的eIF4E/eIF4GI KD在多发性骨髓瘤中的作用进行比较，表明这些TI因子在癌症进展中具有共同作用。
