Jaiswal Praveen Kumar, Koul Sweaty, Palanisamy Nallasivam, Koul Hari K
1Department of Biochemistry and Molecular Biology, LSU Health Sciences Center, 1501 Kings Highway, PO Box 33932, Shreveport, LA 71130-3932 USA.
3Feist Weiller Cancer Center, LSU Health Sciences Center Shreveport, Shreveport, LA 71130 USA.
Cancer Cell Int. 2019 Aug 31;19:224. doi: 10.1186/s12935-019-0947-2. eCollection 2019.
Cap-dependent mRNA translation is essential for the translation of key oncogenic proteins at optimal levels and is highly regulated by the rate limiting, initiation step in protein synthesis. Eukaryotic Translation Initiation Factor 4 Gamma 1 (EIF4G1) serves as a scaffold for assembly of cap-dependent translation components in EIF4F complex formation. In the current study, we analyzed the role and expression of EIF4G1 in Pan human cancer panels through various approaches.
Immunohistochemistry analysis of EIF4G1 protein was done on high-density multi-organ Human Cancer tissue microarray (TMA) derived from the patient samples from different cancers. We used multiple clinical cohorts to analyze the EIF4G1 mRNA expression across human cancers. TCGA data analysis of EIF4G1 was done through Ualcan and c-bioportal web servers. Western blots for EIF4G1 protein was done for different cell lines in representing the multiple cancer types. Dependency score was calculated through Cancer Dependency Map. Clonogenic, tumorosphere assay and cell invasion assay were done with EIF4G complex inhibitor. Association of EIF4G1 mRNA and Kaplan-Meier survival analysis was done on available TCGA datasets.
We observed an increase in EIF4G1 protein levels in tissue sections from different cancers as compared to their respective normal tissue. Our analysis of the TCGA data revealed that EIF4G1 mRNA expression is significantly increased in tumor tissues compared to respective control tissues across human cancers and variable expression was observed among different datasets. We discovered that alteration frequency in EIF4G1 is prevalent in human cancers e.g. prostate cancer (~ 25%), ovarian cancer (~ 15%), Head and Neck cancer (~ 13%) and cervical cancer (~ 12.5%). EIF4G1 mRNA and protein levels were high across cancer cell lines from multiple organs. Our analysis of DepMap datasets utilizing depletion assays revealed that EIF4G1 is critical for cancer cell survival. Treatment with EIF4G complex inhibitor impaired clonogenic, tumorosphere formation potential and inhibited cell invasion. Moreover, higher EIF4G1 mRNA level was associated with a lower median survival of patients in multiple tumor types.
These studies show that EIF4G1 is amplified/over-expressed in multiple cancers and plays an essential role in cancer cell survival, as such EIF4G1 could serve as a novel potential target for therapeutic intervention across many cancers.
帽依赖性mRNA翻译对于关键致癌蛋白在最佳水平的翻译至关重要，并且在蛋白质合成的限速起始步骤中受到高度调控。真核翻译起始因子4γ1（EIF4G1）在EIF4F复合物形成过程中作为帽依赖性翻译组件组装的支架。在本研究中，我们通过多种方法分析了EIF4G1在泛人类癌症样本中的作用和表达。
对来自不同癌症患者样本的高密度多器官人类癌症组织微阵列（TMA）进行EIF4G1蛋白的免疫组织化学分析。我们使用多个临床队列来分析EIF4G1 mRNA在人类癌症中的表达。通过Ualcan和c-bioportal网络服务器对EIF4G1进行TCGA数据分析。对代表多种癌症类型的不同细胞系进行EIF4G1蛋白的蛋白质印迹分析。通过癌症依赖性图谱计算依赖性评分。使用EIF4G复合物抑制剂进行克隆形成、肿瘤球形成测定和细胞侵袭测定。在可用的TCGA数据集中进行EIF4G1 mRNA与Kaplan-Meier生存分析的关联。
我们观察到与各自的正常组织相比，来自不同癌症的组织切片中EIF4G1蛋白水平升高。我们对TCGA数据的分析表明，与人类癌症中各自的对照组织相比，肿瘤组织中EIF4G1 mRNA表达显著增加，并且在不同数据集中观察到可变表达。我们发现EIF4G1中的改变频率在人类癌症中普遍存在，例如前列腺癌（约25%）、卵巢癌（约15%）、头颈癌（约13%）和宫颈癌（约12.5%）。来自多个器官的癌细胞系中EIF4G1 mRNA和蛋白水平都很高。我们利用消耗试验对DepMap数据集的分析表明，EIF4G1对癌细胞存活至关重要。用EIF4G复合物抑制剂处理会损害克隆形成、肿瘤球形成潜力并抑制细胞侵袭。此外，较高的EIF4G1 mRNA水平与多种肿瘤类型患者的较低中位生存期相关。
这些研究表明，EIF4G1在多种癌症中扩增/过表达，并在癌细胞存活中起重要作用，因此EIF4G1可作为许多癌症治疗干预的新潜在靶点。
