Abstract 5388: Metastasis suppressor RKIP modulates mitochondrial metabolism in triple-negative breast cancer

Abstract Triple-negative breast cancer (TNBC) remains the most aggressive subtype of breast cancer, with a high propensity for metastasis. Tumor cell heterogeneity has been closely linked to metastatic progression, therapy resistance, and disease recurrence in solid tumors, including TNBC. Within tumors, metabolic heterogeneity emerges as cancer cells adapt to diverse environmental pressures, further driving tumor aggressiveness. However, the role of metastasis suppressors, such as Raf Kinase Inhibitory Protein (RKIP), in regulating metabolic heterogeneity is not yet fully understood. Analysis of RNA sequencing data from breast cancer patients revealed a strong correlation between RKIP expression and oxidative phosphorylation (OXPHOS) genes. Together with this, by performing gene set enrichment analysis of bulk RNA sequencing of mouse xenografts we observed an enrichment of hallmark of OXPHOS in RKIP-overexpressing tumors compared to controls. Consistent with these findings, RKIP was shown to modulate oxygen consumption rates in vitro. Using stable isotope tracing with [U-13C] glucose in vivo, we observed higher glucose contribution to citrate labeling in RKIP-overexpressing tumors compared to controls. Through single-cell RNA sequencing, we demonstrate that RKIP reduces overall transcriptional heterogeneity, particularly by decreasing the variability of genes involved in mitochondrial respiration. Importantly, treatment with the OXPHOS inhibitor metformin selectively inhibited the growth of RKIP-overexpressing tumors, while control tumors were unaffected. This study suggests that RKIP or drugs that mimic its action have the potential to promote OXPHOS in tumor cells, presenting an opportunity to suppress tumor growth by subsequent therapeutic targeting of mitochondrial respiration in TNBC. Citation Format: Joana Pinheiro, Dongbo Yang, Madeline Henn, Long Chi Nguyen, Olga Martinho, Brandon Faubert, Marsha Rich Rosner. Metastasis suppressor RKIP modulates mitochondrial metabolism in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5388.