Tumor microenvironment-derived IL-32 promotes aggressive phenotypes and stem cell traits in head and neck squamous cell carcinoma.

Background/purpose: Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy distinguished by marked invasiveness, a high metastatic propensity, and poor prognosis. Cancer-associated fibroblasts (CAFs) within the tumour microenvironment secrete numerous mediators that accelerate tumour progression; however, the precise contribution of CAF-derived interleukin-32 (IL-32) remains unclear. This study examined the influence of CAF-derived IL-32 on invasion, epithelial-mesenchymal transition (EMT), and cancer-stem-cell (CSC) traits in HNSCC. Materials and methods: Primary CAFs and normal fibroblasts (NFs) were isolated from HNSCC specimens. IL-32 expression was quantified by microarray analysis, quantitative PCR, Western blotting, and enzyme-linked immunosorbent assay. Migration and invasion of FaDu and SCC25 cells were assessed with Transwell assays after exposure to CAF-conditioned medium or recombinant IL-32. EMT markers were evaluated by Western blotting, whereas sphere-formation assays and flow cytometry for CD133+/CD44+/CD24+ populations were used to determine stemness. Results: IL-32 was significantly up-regulated in CAFs compared with NFs. Both CAF-conditioned medium and recombinant IL-32 markedly increased the migratory and invasive capacities of HNSCC cells. These treatments reduced E-cadherin and increased Vimentin, Snail, and Twist expression, while enhancing sphere formation and expanding CD24+, CD44+ and CD133+ sub-populations. Conclusion: CAFs promote HNSCC progression through IL-32-mediated enhancement of invasion, EMT induction, and CSC properties. Targeting IL-32 signalling may represent a promising therapeutic approach to improve outcomes in HNSCC.