Inhibition of TPI1 Sensitizes Cisplatin-Resistant Oral Cancer to Ferroptosis

<b>Background:</b> Iron metabolism has emerged as a critical factor in cancer biology, with elevated intracellular iron levels contributing to increased oxidative stress and tumorigenesis. However, the molecular determinants governing ferroptosis sensitivity remain incompletely understood. Triosephosphate isomerase 1 (TPI1), a key glycolytic enzyme, has been implicated in cancer progression, but its role in ferroptosis regulation, particularly in the context of chemoresistance, is largely unexplored. In this study, we investigated the impact of TPI1 silencing on ferroptosis in cisplatin-resistant oral squamous cell carcinoma (OSCC), aiming to elucidate its mechanistic role and therapeutic potential. <b>Methods:</b> We conducted in vitro and in vivo analyses to evaluate the functional consequences of TPI1 knockdown in cisplatin-resistant OSCC cell lines and tumor xenograft models. The effects of TPI1 silencing and/or cisplatin treatment were assessed with respect to cell proliferation, migration, and invasion, along with ferroptosis-associated markers, including lipid ROS, free iron levels, lipid peroxidation, and the expression of key ferroptosis-related genes. Additionally, we analyzed the clinical relevance of TPI1 expression in human OSCC tissue samples, examining its association with clinicopathological features and patient prognosis. <b>Results:</b> TPI1 was found to be significantly upregulated in both OSCC tissues and cell lines, and high TPI1 expression correlated with poor clinical outcomes. Multivariate analysis identified TPI1 as an independent prognostic factor for tumor progression. Functionally, TPI1 knockdown suppressed OSCC cell proliferation, migration, and invasion, while its overexpression enhanced these oncogenic behaviors. Mechanistically, silencing TPI1 led to increased intracellular ROS accumulation, elevated free iron, and enhanced lipid peroxidation, collectively promoting ferroptotic cell death in cisplatin-resistant OSCC cells. In vivo, TPI1 depletion resulted in marked tumor growth inhibition and synergized with cisplatin to further suppress tumor burden in xenograft models. Moreover, TPI1 silencing disrupted the epithelial-mesenchymal transition (EMT), a key driver of cancer metastasis and drug resistance. <b>Conclusions:</b> Our study reveals a previously unrecognized role of TPI1 in protecting oral cancer cells from ferroptosis, especially in the setting of cisplatin resistance. These findings suggest that TPI1 not only contributes to tumor aggressiveness but also mediates resistance to ferroptosis. Targeting TPI1 may therefore represent a promising therapeutic strategy to overcome chemoresistance and enhance ferroptosis-based therapies in oral cancer.