Oct4 downregulation-induced inflammation increases the migration and invasion rate of oral squamous cell carcinoma

Abstract

Abstract Inflammatory changes are involved in tumor cell proliferation, migration, and invasion. Tumor necrosis factor-α (TNF-α) and lipopolysaccharide (LPS) play important roles in inflammatory regulation during tumor development. Oct4 acts as a transcription factor that modulates inflammatory changes in mesenchymal stem cells. In this study, we explored the role of Oct4 in the invasion and migration of oral squamous cell carcinoma (OSCC) cells. LPS and TNF-α were used to treat the OSCC cell lines HN4 and CAL27 to induce inflammation. The generation of inflammatory cytokines, including TNF-α, interleukin (IL)-1β, and IL-6, was evaluated by enzyme-linked immunosorbent assay and real-time quantitative PCR. Western blot analysis was employed to detect the expression and phosphorylation of JNK1, p65, and STAT3, which are key modulators of inflammation. Wound scratch healing and transwell invasion assays were further used to determine the role of inflammation in the invasion and migration of OSCC cells. Robust inflammation was observed in HN4 and CAL27 cells treated with LPS and TNF-α. A marked increase in JNK1, p65, and STAT3 phosphorylation levels in OSCC cells was also detected after LPS and TNF-α treatment. The migration and invasion of HN4 and CAL27 cells were significantly boosted by stimulation with LPS and TNF-α. Furthermore, Oct4 mRNA and protein levels were significantly upregulated by stimulation with LPS and TNF-α. Silencing of Oct4 led to reduced inflammation and decreased levels of phosphorylated JNK1, p65, and STAT3 and impaired invasion and migration in LPS- and TNF-α-stimulated OSCC cells. Overall, LPS- and TNF-α-induced inflammation suppressed the migration and invasion of OSCC cells by upregulating Oct4 expression.