Hypoxia amplifies arecoline-induced invasion and metastasis in oral squamous cell carcinoma-Insights into TGF-β1 signaling and collagen production

Background/Purpose: Betel quid chewing is a major risk factor for oral squamous cell carcinoma (OSCC), largely due to arecoline, a key alkaloid. Hypoxia, common in the tumor microenvironment, also influences cancer progression. This study investigated the combined effects of arecoline and hypoxia on proliferation, migration, and protein expression in tongue squamous cell carcinoma (SCC-25) cells, focusing on the TGF-b1 signaling pathway and type I collagen production. Materials and methods: SCC-25 cells were treated with arecoline and incubated for 24 h under normoxia or hypoxia. Cytotoxicity assays and Western blotting were performed to assess cell viability and protein expression. Results: At 2.5 mg/mL, arecoline enhanced SCC-25 cell proliferation under normoxia, while hypoxia suppressed this effect. Arecoline significantly promoted cell migration that was further amplified by hypoxia. Western blotting revealed that arecoline upregulated TGF-b1, Smad2/3, phosphorylated Smad2/3, and type I collagen. Under hypoxia, HIF1-a expression increased along with TGF-b 1 and type I collagen, indicating that hypoxia enhances arecoline-induced collagen production through TGF-b1 signaling. Conclusion: Arecoline stimulates SCC-25 cell proliferation and migration, with hypoxia amplifying these effects by promoting TGF-b1 signaling and type I collagen production. These findings suggest that betel quid consumption, in combination with hypoxia, may exacerbate the invasion and metastasis of OSCC. <feminine ordinal indicator> 2025 Association for Dental Sciences of the Republic of China. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).