Abstract LB018: TMEM65 modulates lipid metabolic reprogramming by stabilizing the MICOS complex to promote gastric cancer metastasis

Abstract Background: Gastric cancer is a heterogeneous malignancy with high lethality. Gastric cancer cells are characterized by abnormal mitochondrial biogenesis and lipid metabolism, including higher levels of fatty acid oxidation (FAO). FAO is an important factor in promoting tumor metastasis, but the underlying mechanism is unclear. Transmembrane protein 65 (TMEM65) is localized in the inner mitochondrial membrane and involved in various biological processes. However, its role remains unknown in the process of FAO. Methods: Single-cell RNA sequencing and an online database were used to analyze the expression difference of TMEM65 in clinical samples. CRISPR-Cas9 technique was performed for TMEM65 knockout. The functions of TMEM65 were determined by CCK8, colony formation, transwell, and seahorse assays. Multi-omics approaches, such as transcriptomics, proteomics, and metabolomics, were used to analyze the metabolic alteration before and after TMEM65 knockout. The binding proteins to TMEM65 were identified by TurboID and IP-MS assays. Electron projection microscopy was used to observe fat droplets, mitochondrial cristae, and mitochondria-associated endoplasmic reticulum (MAM). Subcutaneous and orthotopic xenograft models of animals were applied to test the effects of TMEM65’s expression alteration on the progression of gastric cancer in vivo. Results: Single-cell RNA sequencing showed that metastatic gastric cancer tissues exhibited abnormal lipid metabolism and mitochondrial biogenesis compared to normal lesions. TMEM65 was also accumulated in metastatic gastric cancer tissues and negatively associated with the overall survival of gastric cancer patients. The loss of TMEM65 decreased the ability of cell proliferation and migration, accompanied by the reduction of oxygen consumption rate, intracellular calcium ATP content, and the increase of fat droplets in gastric cancer cells. Mechanically, multiple omics data showed that the FAO level was decreased dramatically in TMEM65-deficient cells. TMEM65 can bind and stabilize the expression of MIC60, one of the main components of the mitochondrial contact site and cristae organizing system (MICOS) complex. Furthermore, we found that the MICOS complex is involved in the maintenance of mitochondrial cristae and the formation of MAM to facilitate FAO, thereby expediting the metastasis of gastric cancer cells. Consistently, TMEM65-deficient cells exhibited damaged mitochondrial cristae and reduced MAM, which could be rescued by the re-overexpression of MIC60 in vivo and in vitro. Conclusions: Taken together, TMEM65 maintains the stability of the MICOS complex and mitochondrial cristae by binding to MIC60, promotes the process of MAM and FAO, and then accelerates gastric cancer metastasis. These findings elucidate the mechanism of TMEM65-mediated metastasis of gastric cancer, and imply TMEM65 is a potential therapeutic target in gastric cancer. Citation Format: Xiao Han, Qi Liu, Chenlu Shen, Tao Lu, Xiangdong Cheng, Shengjie Zhang. TMEM65 modulates lipid metabolic reprogramming by stabilizing the MICOS complex to promote gastric cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB018.