AIMP1 is a novel potential biomarker for LUAD and is associated with improved prognosis
Authors: Wei Qishuang , Liu Lei , Xie Mingjie , Feng Yuqing , Yang Yujia , Liu Yifei , Zhang Jianguo 
Published: November 2022

Abstract
Background: Ammonia acyl tRNA synthase complex interaction of multifunctional protein 1 (AIMP1) is a specific type of cytokine, which controls angiogenesis, inflammation, and the healing of wounds. Previous studies have reported that AIMP1 exhibits anti-tumor activity. However, these studies have not determined the molecular functions of AIMP1. Moreover, scientists have not yet clearly elucidated the relationship between AIMP1 and tumor-infiltrating immune cells (TIICs) of lung adenocarcinoma (LUAD) tissues. In this study, our main aim to understand how AIMP1 is related to the occurrence and development of LUAD. Moreover, we also elucidated the relationship between the expression of AIMP1 and the immune microenvironment. This new idea is the basis for providing targeted treatment to LUAD patients.
Methods: To determine the expression of AIMP1 in LUAD tissues, we used the Tumor Immune Evaluation Resource (TIMER) database. To understand the relationship between the expression of AIMP1 and the survival time of LUAD patients, we constructed the Kaplan-Meier plotter with the help of R software. The LUAD data was downloaded and analyzed from the GEO database. Thus, we established a correlation between AIMP1 and various clinicopathological parameters of LUAD patients. The Western Blot technique and immunohistochemistry (IHC) tests were conducted to ascertain the expression of AIMP1 in 165 LUAD patients, which were recruited from the Affiliated Hospital of Nantong University (Nantong, Jiangsu Province, China). Thereafter, KEGG enrichment analysis and protein-protein interaction (PPI) network analysis were performed to determine the potential biological functions of AIMP1. Furthermore, the relationship between AIMP1 and tumor immune infiltration was revealed by the deconvolution algorithm of the analytical tool named CIBERSORT and the TIMER2.0 database.
Results: The distribution of AIMP1 was estimated in the tumor tissues of all TCGA cancers. We found that the expression of AIMP1 was significantly enhanced in LUAD patients. However, the prognosis of LUAD patients was better when the mRNA expression of AIMP1 was upregulated. Furthermore, the protein level of AIMP1 was significantly greater in LUAD tissues (p < 0.05). By performing multivariate cox analysis, we found that AIMP1 acts as an independent prognostic factor of LUAD. Moreover, the expression of AIMP1 was found to have a correlation with tumor size and lymph node metastasis. The KEGG enrichment analysis and gene ontology (GO) database proved that AIMP1 enriched the immune-related activities of genes co-expressed with AIMP1. Cell cycle, COVID-19, and other signaling pathways were involved in this process. In addition, the expression of AIMP1 was positively correlated to the infiltration of following cell types: CD4 + T cells, activated dendritic cells, and macrophages. At the same time, they were negatively correlated to the infiltration of following cell types: B cells, regulatory T cells, and myeloid dendritic cells.
Conclusions: Our findings indicate that the expression of AIMP1 was an independent prognostic factor of LUAD. Moreover, its overexpression was conducive in creating an anti-tumor immune microenvironment. However, further studies must be conducted to evaluate the potential role of AIMP1, which acts as a biomarker in eliciting an immunotherapeutic effect on LUAD patients.