Integrated analysis of tumor microenvironment features to establish a diagnostic model for papillary thyroid cancer using bulk and single-cell RNA sequencing technology

Background Characterizing tumor microenvironment using single-cell RNA sequencing has been a promising strategy for cancer diagnosis and treatment.

However, a few studies have focused on diagnosing papillary thyroid cancer (PTC) through this technology.

Therefore, our study explored tumor microenvironment (TME) features and identified potential biomarkers to establish a diagnostic model for papillary thyroid cancer.

Methods The cell types were identified using the markers from the CellMarker database and published research.

The CellChat package was conducted to analyze the cell–cell interaction.

The SCEVAN package was used to identify malignant thyroid cells.

The SCP package was used to perform multiple single-cell downstream analyses, such as GSEA analysis, enrichment analysis, pseudotime trajectory analysis, and differential expression analysis.

The diagnostic model of PTC was estimated using the calibration curves, receiver operating characteristic curves, and decision curve analysis.

RT-qPCR was performed to validate the expression of candidate genes in human papillary thyroid samples.

Results Eight cell types were identified in the scRNA-seq dataset by published cell markers.

Extensive cell–cell interactions like FN1/ITGB1 existed in PTC tissues.

We identified 26 critical genes related to PTC progression.

Further, eight subgroups of PTC tumor cells were identified and exhibited high heterogeneity.

The MDK/LRP1, MDK/ALK, GAS6/MERTK, and GAS6/AXL were identified as potential ligand-receptor pairs involved in the interactions between fibroblasts/endothelial cells and tumor cells.

Eventually, the diagnostic model constructed by TRPC5, TENM1, NELL2, DMD, SLC35F3, and AUTS2 showed a good efficiency for distinguishing the PTC and normal tissues.

Conclusions Our study comprehensively characterized the tumor microenvironment in papillary thyroid cancer.

Through combined analysis with bulk RNA-seq, six potential diagnostic biomarkers were identified and validated.

The diagnostic model we constructed was a promising tool for PTC diagnosis.

Our findings provide new insights into the heterogeneity of thyroid cancer and the theoretical basis for diagnosing thyroid cancer.