TFAM loss drives oxaliplatin resistance by linking mtDNA release to STING–TBK1-mediated lysophagy

Abstract

Acquired resistance to oxaliplatin (Oxa) represents a major clinical challenge in the treatment of colorectal cancer (CRC). Lysosomes are intracellular degradative organelles that enable cancer cells to adapt to metabolic and environmental stress; however, their precise regulatory roles in drug resistance remain poorly understood. Here, we report that lysosomal damage and its selective autophagic clearance (lysophagy) occur frequently in both Oxa-treated CRC cells and Oxa-resistant (OxaR) CRC cells. Through quantitative proteomics, we identified the significant downregulation of mitochondrial transcription factor A (TFAM) as a key event in Oxa-treated and OxaR cells. Mechanistically, Oxa-induced TFAM loss leads to mitochondrial DNA (mtDNA) leakage into the cytosol, which activates the STING–TBK1 signaling axis. This pathway subsequently enhances lysophagic flux, providing cancer cells with a survival advantage under Oxa stress. Crucially, pharmacological inhibition of TBK1 abrogates this adaptive lysophagy, restoring Oxa sensitivity and suppressing tumor growth in both xenograft and patient-derived organoid models. Collectively, our study reveals a novel TFAM–mtDNA–STING–TBK1 signaling axis that promotes chemoresistance through the co-option of lysophagy, highlighting TBK1 as a viable therapeutic target to overcome Oxa resistance in CRC. Colorectal cancer is often treated with oxaliplatin, but many tumors become less responsive over time, making treatment harder. This study aimed to understand one way cancer cells escape oxaliplatin and to identify a possible way to restore drug response. The researchers studied colorectal cancer cells, drug-resistant cells, mouse tumor models, and tumor-like structures grown from patient samples. They found that oxaliplatin stress lowers a mitochondrial protein called TFAM. This allows mitochondrial DNA to leak into the cell fluid and switch on a survival signal involving TBK1. This signal helps cancer cells clear damaged cell parts and survive treatment. Blocking TBK1 reduced this protective response and made resistant tumors more sensitive to oxaliplatin. These findings suggest that combining oxaliplatin with a TBK1-blocking treatment may help overcome drug resistance in colorectal cancer in the future.