(S,R)3-(4-Hydroxyphenyl)-4,5-Dihydro-5-Isoxazole Acetic Acid Methyl Ester Inhibits Epithelial-to-Mesenchymal Transition Through TGF-β/Smad4 Axis in Nasopharyngeal Carcinoma

Abstract

Background: Macrophage migration inhibitory factor (MIF), originally reported as an inflammation regulating molecule, is elevated in various cancer cells, which may promote carcinogenesis. Meanwhile, ISO-1 is a potent small molecular inhibitor of MIF, which has not been investigated in nasopharyngeal carcinoma (NPC), hence the impact of ISO-1 on NPC cells remains to be illustrated.

Objective: This study intended to explore the biological function of ISO-1 in NPC cells in vitro and prove a possibility of ISO-1 being a novel agent in NPC treatments.

Methods: Gene expression of MIF in Head and Neck squamous cell carcinoma was obtained from The Cancer Genome Atlas (TCGA) database. Nasal pharyngeal tissues were collected from adult patients undergoing nasopharyngeal biopsy for MIF level detection. Proliferation of NPC cell lines 5-8B and 6-10B was studied using Cell Counting Kit-8 (CCK-8) assay and plate-colony-formation assay, apoptosis was determined by flow cytometry and TUNEL staining, migration and invasion capacities were measured by wound-healing assay and transwell assay, all to explore the function of ISO-1 in NPC cells in vitro. Epithelial-to-mesenchymal transition (EMT) level of NPC cells was determined by Western blot analysis and immunofluorescence assay.

Results: Transcript level of MIF was significantly higher in head and neck squamous cell carcinoma. Protein MIF was overexpressed in human NPC tissues compared to non-cancerous ones, and its expression could be compromised by ISO-1 in vitro. 100μM ISO-1 significantly hindered NPC cells' migration and invasion capacitiesin vitro but acted relatively poorly on proliferation and apoptosis. Immunofluorescence assay and Western blotting implied a downregulated EMT level through TGF-β/Smad4 axis in ISO-1 treated NPC cells compared to the vehicle.

Conclusion: This study indicated that MIF antagonist ISO-1 holds an impact on NPC progression by influencing the migration and invasion of NPC cells ISO-1 inhibits the EMT process of NPC cells through TGF-β/Smad4 axis, supporting that prudent application of ISO-1 may be a potential adjuvant treatment for NPC.

Keywords: ISO-1; NPC; Nasopharyngeal carcinoma; epithelial-to-mesenchymal transition; macrophage migration inhibitory factor; transforming growth factor-β.