Single-cell reveals age-dependent epithelial reprogramming and EMT vulnerability in THCA.

Abstract

Thyroid cancer exhibits pronounced cellular heterogeneity, yet the mechanisms underlying epithelial-mesenchymal transition (EMT) and tumor microenvironment (TME) remodeling remain incompletely understood. In this study, single-cell RNA sequencing of 92,849 cells from 20 thyroid tissue samples derived from underage and adult patients was performed to systematically characterize immune and epithelial heterogeneity through cell type annotation, subclustering, and functional enrichment analyses. A total of 26 distinct cell clusters were identified, encompassing immune and stromal compartments, with notable age- and stage-specific differences in T cell, epithelial, and macrophage subsets. EMT-high tumors were characterized by stromal enrichment, immune suppression, and transcriptional activation of canonical EMT drivers, including TGFB1, SNAI1/2, TWIST1/2, and ZEB1/2. Functional validation demonstrated that shRNA-mediated knockdown of PHTF2 or SNAI1 in TPC-1 and KTC-1 cell lines significantly inhibited proliferation and clonogenic capacity, accompanied by upregulation of CDH1 and downregulation of multiple EMT-associated genes. Furthermore, EMT-high tumors exhibited distinct drug sensitivity profiles, including reduced responsiveness to conventional chemotherapeutics and increased sensitivity to agents such as camptothecin and dabrafenib. Collectively, these findings identify PHTF2 and SNAI1 as key regulators of EMT and tumor cell proliferation in thyroid cancer, and suggest that EMT-driven TME remodeling contributes to immune evasion and therapeutic resistance, thereby revealing EMT-associated vulnerabilities as potential targets for precision therapy.