Inhibition of extracellular matrix remodeling and metastatic activity by dichloroacetate and chloroquine in the presence of arsenite in 4nqo-induced oral squamous cell carcinoma

Introduction: Oral squamous cell carcinoma (OSCC) is characterized by extracellular matrix (ECM) remodeling associated to a pro-inflammatory and protumoral metabolic activity that promote invasion and metastatic progression. This study assessed the effect of a triple therapy combining sodium arsenite (NaAsO2), chloroquine (CQ), and dichloroacetate (DCA) on inflammatory signaling and ECM remodeling in a 4-nitroquinoline-1-oxide (4NQO)-induced tongue OSCC mouse model. Methods: Eight-week-old female BALB/c mice were exposed to chemical induction with the carcinogen (100 µg/ml) or treated with placebo (water control) for 16 weeks, then observed for up to 16 additional weeks. At 32 weeks post-treatment, mice were sacrificed, and their tongues were removed. The oral tumor tissues were then cultured for 24 hours in the presence of NaAsO2, CQ, and DCA. Tumor tissues and explants were analyzed for TNF-alpha, nitric oxide (NO), matrix metalloproteinase-9 (MMP-9), and collagen integrity. Results: 4NQO carcinogenic activity on animal tongues led to a significant development of dysplasia and invasive SCC cases. OSCC explants culture showed in comparison to healthy tissues elevated levels of nitric oxide production, associated with increased expression of the pro-tumoral TNF-alpha, MMP-9 expression and collagen fiber disorganization were increased in such conditions. Surprisingly whereas NaAsO2 alone amplified inflammatory mediators, its combination with CQ and DCA significantly decreased NO and TNF-alpha levels. Strikingly this effect led to a significant downregulation of MMP-9, and preserved Type IV collagen architecture. Masson's trichrome staining revealed a restoration of dense, parallel collagen fibers resembling those found in an ECM architecture observed in low-grade dysplasic tongues in comparison with OSCC. These findings demonstrate that TNF-alpha/NO-driven MMP-9 activation is a central mechanism of ECM degradation in OSCC, and that a simultaneous modulation of aerobic glycolysis and autophagy may disrupt the metastatic signaling axis involved in extracellular matrix remodeling and metastatic activity in 4nqo-induced oral squamous cell carcinoma. Conclusion: Altogether, our findings show that our combined treatment was able to reprogram the inflammatory process of tumor progression by inhibiting the molecular processes involved in extracellular matrix remodeling and invasion. This combined treatment represents a novel avenue for metabolic-inflammation-targeting strategy for OSCC in particular in view of the limited treatment options and the risk of chemoresistance.