Epigenetic silencing of <i>JAM3</i> promotes laryngeal squamous cell carcinoma development by inhibiting the Hippo pathway

Laryngeal squamous cell carcinoma (LSCC), which represents a significant proportion of head and neck squamous cell carcinoma cases, is often diagnosed at advanced stages, underscoring the urgent need for effective biomarkers and therapeutic targets. Junctional adhesion molecule 3 (<i>JAM3</i>) is implicated in various types of cancer; however, its role in LSCC remains unclear. Therefore, the present study aimed to investigate the epigenetic regulation and tumor‑suppressive functions and mechanisms of <i>JAM3</i> in LSCC. Bioinformatics analysis and 5‑Aza‑2'‑deoxycytidine treatment, which restored <i>JAM3</i> expression as confirmed by reverse transcription‑quantitative PCR and western blotting, revealed that aberrant hypermethylation of the <i>JAM3</i> promoter was associated with reduced <i>JAM3</i> expression and poorer clinical outcomes in patients with LSCC. <i>In vitro</i> experiments, including Cell Counting Kit 8, colony formation and Transwell assays, demonstrated that <i>JAM3</i> overexpression inhibited LSCC cell proliferation, migration and invasion. Western blotting and immunofluorescence analysis revealed that the tumor‑suppressive function of JAM3 was mediated through activation of the Hippo pathway. By contrast, both <i>in vitro</i> and <i>in vivo</i> experiments showed that <i>JAM3</i> knockdown enhanced these oncogenic behaviors by inhibiting the Hippo pathway, suggesting its critical tumor‑suppressive role. In conclusion, the results of the present study indicated that <i>JAM3</i> may be epigenetically downregulated and could function as a novel tumor suppressor gene through the Hippo pathway in LSCC, offering insights into developing targeted treatments and diagnostics.