Targeting metabolic vulnerability in mitochondria conquers MEK inhibitor resistance in KRAS-mutant lung cancer.

Acta Pharmaceutica Sinica B 2023;13(3):1145e1163 Chinese Pharmaceutical Association Institute of Materia Medica, Chinese Academy of Medical Sciences Acta Pharmaceutica Sinica B w w w. e l s ev i e r. c o m / l o c a t e / a p s b w w w. s c i e n c e d i r e c t . c o m ORIGINAL ARTICLE Targeting metabolic vulnerability in mitochondria conquers MEK inhibitor resistance in KRAS-mutant lung cancer Juanjuan Fenga,b,y, Zhengke Liana,y, Xinting Xiaa, Yue Lua, Kewen Huc, Yunpeng Zhanga, Yanan Liua, Longmiao Hua, Kun Yuana, Zhenliang Sunb,*, Xiufeng Panga,* a Shanghai Key Laboratory of Regulatory Biology, School of Life Sciences, East China Normal University, Shanghai 200241, China b Joint Center for Translational Medicine, Southern Medical University Affiliated Fengxian Hospital, Shanghai 201499, China c Cancer Institute, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China Received 15 May 2022; received in revised form 18 August 2022; accepted 23 September 2022 KEY WORDS KRAS-mutant lung cancer; MEK inhibitors; Drug resistance; Metabolic rewiring; Mitochondrial oxidative phosphorylation; Pyruvate dehydrogenase complex; Carnitine palmitoyl transferase IA Abstract MEK is a canonical effector of mutant KRAS; however, MEK inhibitors fail to yield satisfactory clinical outcomes in KRAS-mutant cancers. Here, we identified mitochondrial oxidative phosphorylation (OXPHOS) induction as a profound metabolic alteration to confer KRAS-mutant non-small cell lung cancer (NSCLC) resistance to the clinical MEK inhibitor trametinib. Metabolic flux analysis demonstrated that pyruvate metabolism and fatty acid oxidation were markedly enhanced and coordinately powered the OXPHOS system in resistant cells after trametinib treatment, satisfying their energy demand and protecting them from apoptosis. As molecular events in this process, the pyruvate dehydrogenase complex (PDHc) and carnitine palmitoyl transferase IA (CPTIA), two rate-limiting enzymes that control the metabolic flux of pyruvate and palmitic acid to mitochondrial respiration were activated through phosphorylation and transcriptional regulation. Importantly, the co-administration of trametinib and IACS-010759, a clinical mitochondrial complex I inhibitor that blocks OXPHOS, significantly impeded tumor growth and prolonged mouse survival. Overall, our findings reveal that MEK inhibitor therapy creates a metabolic vulnerability in the mitochondria and further develop an effective combinatorial strategy to circumvent MEK inhibitors resistance in KRASdriven NSCLC. *Corresponding authors. Tel.: þ86 21 24206942, þ86 21 57416150. E-mail addresses: (Xiufeng Pang), (Zhenliang Sun). y These authors made equal contributions to this work. Peer review under responsibility of Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. https://doi.org/10.1016/j.apsb.2022.10.023 2211-3835 ª 2023 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1146 Juanjuan Feng et al. ª 2023 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction Lung cancer is the leading cause of global cancer-related deaths1, of which non-small cell lung cancer (NSCLC) is the predominant type, accounting for approximately 80%e85% of all lung cancers2. Oncogenic KRAS, one of the most commonly mutated oncogenes in NSCLC (w30%), remains refractory to targeted therapies to date2,3. Recently, the discovery of a new pocket under the effector-binding switch II region of KRAS(G12C) has enabled the successful direct targeting of KRAS(G12C) variants4. However, the acquired resistance of KRAS-addicted tumor cells to new drugs limits their efficacy5. Despite efforts to directly target mutant KRAS, most therapeutic approaches have focused on RAS downstream pathways as a more tractable alternative6,7. Multiple lines of evidence have highlighted that the RAFeMEKeERK kinase cascade (MAPK) is a critical effector pathway underlying mutated RAS. Small inhibitors targeting this pathway have been successfully developed. Although some are US Food and Drug Administration (FDA)approved, most therapeutic approaches have limited efficacy and are poorly tolerated at doses needed to sufficiently extinguish RAS signaling in tumors8. MEK inhibitors (MEKi) are currently used for BRAF-mutant melanoma and neurofibromatosis; however, clinical trials for KRAS-mutant NSCLC are less encouraging9,10. The failure of MEKi in NSCLC is due to multiple mechanisms, including secondary MEK mutations11, immune escape12, reactivation of the MAPK pathway by RAF dimerization13, or compensatory induction of RAS-related pathways14e16, which inevitably leads to the development of therapy resistance and disease recurrence. These molecular discoveries have successfully promoted the clinical application of MEKi in combination with other targeted interventions17,18. However, it is difficult to restore the sensitivity of KRAS-mutant NSCLC cells to MEKi. Further studies regarding the resistance mechanisms of MEKi and exploration of rational treatment strategies are required to augment the response to MEKi-based therapy. Metabolic plasticity is a key feature of cancer cells, which orchestrates their metabolism to meet the high need for energy and building blocks during growth or stress adaptation19,20. EGFR inhibitors have been reported to enhance cystine uptake and glutathione de novo synthesis, protecting cells from killing21. Recent studies have indicated that mitochondrial function contributes to the intrinsic and acquired resistance of certain types of cancer to targeted therapies. BRAF inhibitors reduce tumor glycolysis while inducing mitochondrial oxidative phosphorylation (OXPHOS) by triggering the expression of a mitochondrial biogenesis gene signature, thereby conferring resistance of BRAFV600E-mutant melanoma to BRAF inhibitors22,23. MET inhibitors enhance mitochondrial OXPHOS and fatty acid oxidation (FAO) in glioblastoma, resulting in acylcarnitine accumulation and reduced therapeutic efficacy24. This evidence that drugresistant tumor cells rely more on mitochondrial OXPHOS and less on glycolysis challenges the contention that tumor cells are usually characterized by the Warburg effect, that is, the production of ATP mostly from glycolysis and not oxidative phosphorylation, even under conditions of high oxygen availability. However, it remains unclear whether mitochondrial function and metabolic flexibility contribute to MEKi resistance in KRAS-mutant NSCLC cells (...truncated)