[FCN3 Can Serve as A Potential Biomarker for Prognosis and 
Immunotherapy of Lung Squamous Cell Carcinoma]

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths worldwide. Lung squamous cell carcinoma (LUSC) is an important pathological subtype of NSCLC. The complex immune escape mechanism limits the effectiveness of immunotherapy. Ficolin-3 (FCN3) is a crucial immunomodulatory molecule that regulates immune escape by remodeling the tumor microenvironment. However, the role of FCN3 in LUSC remains unclear. This study employed bioinformatics methods to analyze LUSC samples from The Cancer Genome Atlas (TCGA) database. The aim of this study was to explore the potential biological functions and prognostic significance of FCN3 in LUSC.

A pan-cancer analysis characterized the expression patterns and prognostic value of FCN3 across various cancer types. Simultaneously, the expression patterns of FCN3 in LUSC samples from the TCGA database and its relationship with prognosis were analyzed. The Nomogram model and somatic mutation analysis, differential expression analysis, correlation analysis, as well as Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) were constructed to explore the potential mechanisms of FCN3. Additionally, immune infiltration analysis, immune escape score (TIDE), and correlation analysis of immune-related molecules were used to reveal the regulatory role of high FCN3 levels on immunity in LUSC. Furthermore, the correlation between FCN3 expression characteristics and drug sensitivity was evaluated. Finally, in vitro experiments verified the expression characteristics of FCN3 in LUSC.

The expression level of FCN3 in LUSC tissues was significantly lower than that in normal tissues. Patients with high FCN3 expression in LUSC had a poorer prognosis compared to those with low expression. Different expression levels of FCN3 were associated with the abundance of immune cell infiltration and immune cell dysfunction. It was also linked to the expression of immune checkpoints, immune stimulatory molecules, major histocompatibility complex (MHC) class molecules, and chemotherapy drug sensitivity.

High expression of FCN3 in LUSC is associated with poor prognosis and is linked to immune cell infiltration, immune-related pathways, and immune-related molecules. FCN3 may be a potential prognostic marker and a new target for immunotherapy in LUSC.