Zoledronic acid inhibits thyroid cancer stemness and metastasis by repressing M2-like tumor-associated macrophages induced Wnt/β-catenin pathway

Abstract

AimsThis study aims to explore the effect and underlying mechanism of zoledronic acid (ZA) on the incidence of thyroid cancer (TC) tumorigenesis. Materials and methodsHuman mononuclear cells THP-1 were differentiated into M2-like tumor associated macrophages (TAMs) by incubation with PMA followed by additional incubation of IL-4 and IL-13. TC cells TPC-1 and IHH4 were co-cultured with M2-like TAMs. Identification of M2-like TAMs markers were determined by immunohistochemistry or flow cytometry. Cell proliferation, stemness and migration/invasion ability were measured by colony, sphere formation assay and transwell assay, respectively. The expression levels of cell stemness, EMT and Wnt/β-catenin pathway-related factors were verified by qRT-PCR, Western blotting, and immunofluorescence. A subcutaneous tumor model was established in nude mice to examine the in vivo effects of ZA. Key findingsM2-like TAMs were enriched in TC tissues, and they promoted the colony/sphere formation, accompanied with a down-regulated expression in E-cadherin and an up-regulated expression in N-cadherin, Vimentin and other stemness-associated markers (CD133, Oct4, c-Myc) in TC cells. The effects were suppressed when ZA co-treatment was given, because ZA inhibited the polarization of M2-like TAMs and β-catenin entry into the nucleus. Moreover, in agreement with in vitro data, ZA also limited subcutaneous tumor formation and macrophage enrichment in nude mice. SignificanceZA suppressed M2-like TAMs induced TC cell proliferation, stemness and metastasis through inhibiting M2-like TAMs polarization and Wnt/β-catenin pathway, which sheds light on the mechanisms of TC and provides avenues for the development of clinical therapy to TC.