IDDF2024-ABS-0284 NDUFA4L2 promotes CRC metastasis by triggering immune evasion via suppressing the cGAS-STING-TBK1 pathway

<h3>Background</h3> The ability of cancer cells to evade immune surveillance plays a critical role in cancer relapse and metastasis. NDUFA4L2 is a gene encoding the protein NADH dehydrogenase (ubiquinone)-1α subcomplex 4-like 2, which participates in the functionality of the mitochondrial respiratory chain. The present study investigates the role of NDUFA4L2 in colorectal cancer (CRC) metastasis and tumor immunity. <h3>Methods</h3> NDUFA4L2 gene was identified through RNA-seq screening in a metastatic CRC mouse model. CRC tissues and adjacent normal tissues were used to study the correlation between NDUFA4L2 expression level and CRC metastasis. The role of NDUFA4L2 in CRC metastasis was studied utilizing CRC cell lines. MitoSOX red staining was used to assess mitochondrial ROS level. Semi-quantitative PCR was conducted to evaluate mitochondrial DNA common deletion (CD). The effect of NDUFA4L2 on tumor immune evasion was determined by OT-1-mediated tumor-killing assay. <h3>Results</h3> We discovered that NDUFA4L2 was abnormally overexpressed in CRC tissues and correlated with poor prognosis (IDDF2024-ABS-0284 Figure 1, IDDF2024-ABS-0284 Figure 2). Functional assays indicated that NDUFA4L2 promoted the migration and invasion of CRC cells (IDDF2024-ABS-0284 Figure 3). Additionally, we observed that overexpression of NDUFA4L2 suppressed ROS accumulation, thereby reducing oxidative damage to mtDNA. As mtDNA damage might lead to the accumulation of cytosolic mtDNA and triggering of cGAS-STING-TBK1 activation, we observed NDUFA4L2 knockdown promoted p-IRF3, p-STING, and p-TBK1 expression (IDDF2024-ABS-0284 Figure 4 (A-C)). Furthermore, silencing of NDUFA4L2 impaired the capability of OT-I-derived CD8+ T cell-mediated tumor killing, indicting the role of NDUFA4L2 in promoting tumor immune evasion (IDDF2024-ABS-0284 Figure 4 (D)). <h3>Conclusions</h3> Our data indicate that NDUFA4L2 overexpression can promote immune evasion by inhibiting the cGAS-STING-TBK1 pathway, thus facilitating CRC metastasis. Targeting NDUFA4L2 in combination with immune checkpoint blockade may represent a potential strategy for treating CRC metastasis.