Ferroptosis-related LINC02535/has-miR-30c-5p/EIF2S1 axis as a novel prognostic biomarker involved in immune infiltration and progression of PDAC.

ABSTRACT

BACKGROUND: PDAC, also known as pancreatic ductal adenocarcinoma, is often diagnosed at a late stage due to nonspecific symptoms and a distinct lack of reliable biomarkers for timely diagnosis. Ferroptosis, a novel non-apoptotic cell death mode discovered in recent years, is strongly linked to the progression of PDAC and the evasion of the immune system. The objective of this study is to discover a novel ceRNA biomarker associated with ferroptosis and investigate its possible molecular mechanisms and therapeutic potential in PDAC. METHODS: Based on the FerrDb and TCGA databases, the R survival package was used to screen for ferroptosis-related mRNAs associated with PDAC prognosis. The ferroptosis-related ceRNA network was identified by miRTarBase, miRNet, and starBase and visualized using Cytoscape. The LASSO regression analysis was used to build a risk model associated with ceRNA. Additionally, we investigated the correlation between the ceRNA axis and the infiltration of immune cells in PDAC by employing the ssGSEA algorithm. Spearman correlation analysis was used to investigate the association between the ceRNA network and the expression levels of immune checkpoint genes in PDAC. The prediction of potential medications for PAAD patients with high risk scores was conducted using the R package oncoPredict and the Genomics of Drug Sensitivity in Cancer (GDSC) repository. Expression levels of LINC02535 in clinical specimens and PDAC cell lines were determined using qRT-PCR. CCK-8, colony formation, EdU, wound healing, and transwell assays were performed to assess the impact of reducing LINC02535 on the growth, migration, and invasion of PDAC cell lines BxPC3 and PANC1. RESULTS: We first discovered a new LINC02535/miR-30c-5p/EIF2S1 axis associated with ferroptosis and created a prognostic nomogram for predicting overall survival. Meanwhile, the risk scores of the LINC02535/miR-30c-5p/EIF2S1 axis associated with ferroptosis were linked to immune subtypes in PDAC. The high immune infiltration subtype exhibited elevated ceRNA risk scores and EIF2S1 expression. The correlation analysis revealed a positive correlation between ceRNA risk scores and four immune cells, namely Activated CD4 T cell, Memory B cell, Neutrophil, and Type 2 T helper cell, as well as four immune checkpoint genes, namely CD274, HAVCR2, PDCD1LG2, and TIGIT. The analysis of drug sensitivity indicated that individuals with a high-risk score may exhibit greater sensitivity to inhibitors targeting MEK1/2 compared to those with a low-risk score. In our validation experiments, it was observed that the expression of LINC02535 was increased in both PDAC tissues and cell lines. Additionally, the inhibition of LINC02535 resulted in decreased proliferation, migration, and invasion of PDAC cells. Rescue experiments demonstrated that LINC02535 promoted PDAC cell growth and metastasis by upregulating EIF2S1 expression. CONCLUSION: To summarize, a novel ferroptosis-associated LINC02535/miR-30c-5p/EIF2S1 ceRNA network for PDAC patients was established. The analysis of this network's functionality offers potential insights for clinical decision-making and the advancement of precision medicine.