Abstract P3-06-16: Synergistic effect of biguanides and fatty acid β-oxidation inhibitor in triple-negative breast cancers

Abstract

Abstract Triple negative breast cancer (TNBC) is one of non-targetable cancers which are still poorly understood for the driver pathways and therapeutic targets. Over the past decade, cancer metabolism researches have a huge advance. Thus, it has enhanced our understanding on metabolic reprogramming in cancer therapy. We have previously shown that metabolic reprogramming to fatty acid β-oxidation (FAO) is a key energy metabolic pathway in TNBC. Moreover, we reported that FAO regulates c-Src, one of the frequently upregulated oncopathways in TNBC via autophosphorylation of Src at Y419. However, single treatment by FAO inhibitor alone cannot effectively control the tumor progression in TNBC because of metabolic reprogramming and flexibility of tumors. Therefore, proper combination therapies with other metabolic targets are necessary. Recently increasing studies demonstrate that anti-diabetic biguanides have attractive anti-cancer effect in various cancer types including breast cancer (BC). However, its significance as an anti-cancer drug is not well established due to parallel metabolic pathways that support tumor growth. Biguanide like metformin is the most widely administered anti-diabetic agent worldwide. Phenformin, a biguanide derivative similar to metformin, has a greater potency than metformin. Like metformin, phenformin also inhibits mitochondrial electron transport chain (ETC) through complex I inhibition. In addition, biguanides lead to the activation of AMPK, which plays a important role in insulin signaling and energy sensing. Importantly, AMPK is an upstream regulator of FAO pathway because it can phosphorylate ACC to activate FAO. Considering the dependency of TNBC to FAO, we evaluated the therapeutic significance of the combination of biguanides (ETC inhibitors) and FAO inhibitors in TNBC progression and metastasis. And we investigated that targeting both ‘arms’ of the pathway can provide more effective and durable responses in TNBC treatments. Our various in vitro and in vivo studies using TNBC cell lines and PDX models suggest that the combination of both inhibitors can provide better therapeutic benefits in TNBCs. This is a rationale and cost-effective metabolic approach to overcome the currently non-targetable TNBCs. Further study toward the clinical effectiveness of this combination may offer better treatment opportunities for TNBC patients. Citation Format: Jun Hyoung Park, Kwang Hwa Jung, Dongya Jia, Benny A Kaipparettu. Synergistic effect of biguanides and fatty acid β-oxidation inhibitor in triple-negative breast cancers [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-06-16.