CREM regulates the tumor immune microenvironment and predicts prognosis in thyroid carcinoma

Thyroid cancer (THCA) is increasingly prevalent worldwide, particularly among women, highlighting the need for novel molecular biomarkers to improve early detection and prognostic assessment. The role of the cAMP response element modulator (CREM) gene in THCA remains poorly understood. This study aimed to investigate CREM's expression, clinical significance, and association with the tumor immune microenvironment.

Transcriptomic and clinical data from 507 THCA cases and 59 normal controls in The Cancer Genome Atlas (TCGA) were analyzed. CREM expression was compared across clinical subgroups using non-parametric tests. Survival outcomes were assessed via Kaplan-Meier curves and Cox regression. Receiver operating characteristic (ROC) analysis evaluated diagnostic value. Immune cell infiltration was quantified cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT). Functional enrichment Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) and least absolute shrinkage and selection operator (LASSO)-Cox modeling identified CREM-associated genes, with protein-protein interaction (PPI) networks constructed via the STRING database.

CREM expression was significantly downregulated in THCA compared to normal tissues (P<0.001), with diagnostic potential [area under the curve (AUC) =0.751]. Low CREM expression was associated with advanced tumor stage and poorer prognosis. High CREM levels predicted longer progression-free survival [hazard ratio (HR) =0.53, P=0.02]. CREM expression negatively correlated with infiltration by regulatory T cells (Tregs) and the expression of Treg-specific chemokines. CREM expression also negatively correlated with several immune checkpoints. IL37 and PSG6 were inversely correlated with CREM and associated with poor outcomes, while RCAN1 showed a positive correlation and favorable prognosis.

CREM may function as a tumor suppressor and immune regulator in THCA. Its expression correlates with reduced immune infiltration and improved clinical outcomes, suggesting its potential as a prognostic biomarker and therapeutic target. Further experimental validation is warranted.