Background: N6-methyladenosine (m⁶A) modification is the most common chemical modification in mammalian mRNAs, and it plays important roles by regulating several cellular processes. Previous studies report that m⁶A is implicated in modulating tumorigenesis and progression. However, dysregulation of m⁶A modification and effect of m⁶A demethylase fat-mass and obesity-associated protein (FTO) on glucose metabolism has not been fully elucidated in papillary thyroid cancer (PTC). Methods: Quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry were performed to explore the expression profile of FTO in PTC tissues and adjacent non-cancerous thyroid tissues. Effects of FTO on PTC glycolysis and growth were investigated through in vitro and in vivo experiments. Mechanism of FTO-mediated m⁶A modification was explored through transcriptome-sequencing (RNA-seq), methylated RNA immunoprecipitation sequencing (MeRIP-seq), MeRIP-qPCR, luciferase reporter assays, RNA stability assay and RNA immunoprecipitation assay. Results: FTO expression was significantly downregulated in PTC tissues. Functional analysis showed that FTO inhibited PTC glycolysis and growth. Further analyses were conducted to explore FTO-mediated m⁶A modification profile in PTC cells and Apolipoprotein E (APOE) was identified as the target gene for FTO-mediated m⁶A modification using RNA-seq and MeRIP-seq. FTO knockdown significantly increased APOE mRNA m⁶A modification and upregulated its expression. FTO-mediated m⁶A modification of APOE mRNA was recognized and stabilized by the m⁶A reader IGF2BP2. The findings showed that APOE also promoted tumor growth through glycolysis in PTC. Analysis showed that FTO/APOE axis inhibits PTC glycolysis by modulating IL-6/JAK2/STAT3 signaling pathway. Conclusion: FTO acts as a tumor suppressor to inhibit tumor glycolysis in PTC. The findings of the current study showed that FTO inhibited expression of APOE through IGF2BP2-mediated m⁶A modification and may inhibit glycolytic metabolism in PTC by modulating IL-6/JAK2/STAT3 signaling pathway, thus abrogating tumor growth.

Papillary thyroid carcinoma (PTC) undergoes dedifferentiation into aggressive poorly differentiated (PDTC) or anaplastic (ATC) carcinomas in 10–15% of cases, a process potentially driven by cancer-associated fibroblasts (CAFs) within the tumor microenvironment (TME), though their spatiotemporal dynamics remain poorly understood. Resveratrol (Res), a natural compound, has shown anticancer potential by promoting redifferentiation and apoptosis while inhibiting oncogenic signaling, suggesting utility in countering PTC dedifferentiation. Using spatial transcriptomics (10× Visium) on three surgical specimens, we obtained 14,191 high-quality spots annotated via UMAP and Leiden clustering into seven cell types, including CAFs, T cells, B cells, and others. Comparative gene expression and functional enrichment analyses revealed CAFs in poorly differentiated regions exhibited heightened glycolytic activity, correlated with ZFP57 upregulation and PKM2 induction. Glycolysis was validated through immunofluorescence, Seahorse assays, glucose/lactate measurements, and ZFP57-PKM2 reporter assays. CAF-conditioned media promoted PTC proliferation, invasion, and dedifferentiation while reducing radioiodine uptake in co-culture models. In xenografts, ZFP57 overexpression increased tumor growth and impaired radioiodine retention, whereas Res suppressed ZFP57, restored differentiation, enhanced radioiodine avidity, and inhibited glycolysis. Mechanistically, CAF-secretated lactate activated TGF-β/Smad2/3 signaling, fostering dedifferentiation and malignancy. Resveratrol reversed these effects by targeting ZFP57, normalizing CAF metabolism, and restoring PTC differentiation, indicating a promising therapeutic strategy against PTC progression.