title: Mild Alkalization Acutely Triggers the Warburg Effect by Enhancing Hexokinase Activity via Voltage-Dependent Anion Channel Binding.
abstract: To fully understand the glycolytic behavior of cancer cells, it is important to recognize how it is linked to pH dynamics. Here, we evaluated the acute effects of mild acidification and alkalization on cancer cell glucose uptake and glycolytic flux and investigated the role of hexokinase (HK). Cancer cells exposed to buffers with graded pH were measured for 18F-fluorodeoxyglucose (FDG) uptake, lactate production and HK activity. Subcellular localization of HK protein was assessed by western blots and confocal microscopy. The interior of T47D breast cancer cells was mildly alkalized to pH 7.5 by a buffer pH of 7.8, and this was accompanied by rapid increases of FDG uptake and lactate extrusion. This shift toward glycolytic flux led to the prompt recovery of a reversed pH gradient. In contrast, mild acidification rapidly reduced cellular FDG uptake and lactate production. Mild acidification decreased and mild alkalization increased mitochondrial HK translocation and enzyme activity. Cells transfected with specific siRNA against HK-1, HK-2 and voltage-dependent anion channel (VDAC)1 displayed significant attenuation of pH-induced changes in FDG uptake. Confocal microscopy showed increased co-localization of HK-1 and HK-2 with VDAC1 by alkaline treatment. In isolated mitochondria, acidic pH increased and alkaline pH decreased release of free HK-1 and HK-2 from the mitochondrial pellet into the supernatant. Furthermore, experiments using purified proteins showed that alkaline pH promoted co-immunoprecipitation of HK with VDAC protein. These findings demonstrate that mild alkalization is sufficient to acutely trigger cancer cell glycolytic flux through enhanced activity of HK by promoting its mitochondrial translocation and VDAC binding. This process might serve as a mechanism through which cancer cells trigger the Warburg effect to maintain a dysregulated pH.
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.
authors.forename: Cung Hoa Thien
authors.initials: CH
authors.lastname: Quach
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.|Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kyung-Ho
authors.initials: KH
authors.lastname: Jung
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.|Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.|Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jin Won
authors.initials: JW
authors.lastname: Park
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Moon
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Cho
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.|Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yearn Seong
authors.initials: YS
authors.lastname: Choe
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.|Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kyung-Han
authors.initials: KH
authors.lastname: Lee
mesh_terms: D045744:Cell Line, Tumor; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006019:Glycolysis; D006593:Hexokinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D047468:Immunoprecipitation; D019344:Lactic Acid / Q000378:metabolism; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D050995:Voltage-Dependent Anion Channel 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; C494762:VDAC1 protein, human; D019788:Fluorodeoxyglucose F18; D019344:Lactic Acid; D050995:Voltage-Dependent Anion Channel 1; C472074:HK1 protein, human; D006593:Hexokinase