Hypoxia-induced HMGB1/NLRP3/Caspase-1 signaling axis enhances proliferation of oral squamous cell carcinoma.

Abstract

Background: The hypoxic microenvironment, a common feature of solid tumors, is critically involved in driving cancer malignancy. This research focuses on elucidating the function of high mobility group box 1 (HMGB1), induced by such hypoxia, in the context of oral squamous cell carcinoma (OSCC).

Methods: We first profiled HMGB1 expression patterns in clinical OSCC specimens and evaluated their potential associations with clinicopathological parameters. To functionally characterize HMGB1, we conducted in vitro experiments utilizing silencing strategies. The impact of chronic cyclic hypoxia and HMGB1 depletion on key cellular processes-including proliferation, pyroptosis, and cell cycle-was systematically examined in OSCC cells. Signaling activity along the HMGB1/NLRP3/Caspase-1 axis was determined by immunoblotting. Furthermore, in vivo relevance was substantiated through murine xenograft models and a 4-NQO-induced carcinogenesis protocol.

Results: Analysis of clinical samples revealed that HMGB1 is constitutively upregulated in OSCC tissues. This elevated expression demonstrated a positive relationship with both increased tumor dimensions and lymph node metastasis. Subsequent Kaplan-Meier survival curves indicated that heightened HMGB1 levels are a marker for unfavorable patient outcomes. Furthermore, in cell culture systems, hypoxia treatment significantly elevates HMGB1 expression levels in OSCC cells. Knockdown of HMGB1 expression inhibits hypoxia-induced NLRP3, cleaved-caspase-1, and HIF-1α expression. Hypoxia treatment markedly enhanced OSCC cell proliferation, induced pyroptosis, and alleviated G2/M phase arrest, while HMGB1 knockdown reversed the pro-tumor effects of hypoxia. In vivo experiments demonstrated that HMGB1 knockdown inhibited tumor growth, whereas NLRP3 or caspase-1 deficiency delayed oral cancer progression.

Conclusion: Our findings suggested that HMGB1 contributes to the progression of OSCC and has prognostic value. Targeting the hypoxia-induced HMGB1/NLRP3/Caspase-1 signaling axis may offer a viable therapeutic strategy.