TIMP1 promotes thyroid cancer cell progression through macrophage phenotypic polarization via the PI3K/AKT signaling pathway.

Increasing evidence suggests that tissue inhibitor of metalloproteinase 1 (TIMP1) played a pivotal role in immune regulation. Our study focused on examining the expression and function of TIMP1 in humans, particularly in its regulation of tumor-associated macrophages (TAMs) in papillary thyroid carcinoma (PTC). We observed an upregulation of TIMP1 in 16 different types of malignancies, including thyroid cancer. TIMP1 shaped the inflammatory TME in PTC. Inhibiting the expression of TIMP1 has been demonstrated to reduce the malignant biological traits of PTC cells. Furthermore, reducing TIMP1 expression impeded M2 macrophage polarization as well as facilitated M1 macrophage polarization in PTC. ELISA results demonstrated that downregulated TIMP1 expression correlated with decreased levels of IL10 and TGF-β in cell supernatants. Furthermore, the supernatant from polarized macrophages in the TIMP1-silenced group inhibited the motility of wild-type PTC cells. Therefore, TIMP1 may enhance the progression of PTC by stimulating the PI3K/AKT pathway via the secretion of IL10 and TGF-β, consequently influencing M2-type polarization in TAMs.