Abstract
Acidosis arises in solid and lymphoid malignancies secondary to altered nutrient supply and utilization. Tumor acidosis correlates with therapeutic resistance, although the mechanism behind this effect is not fully understood. Here we show that incubation of lymphoma cell lines in acidic conditions (pH 6.5) blocks apoptosis induced by multiple cytotoxic metabolic stresses, including deprivation of glucose or glutamine and treatment with dexamethasone. We sought to examine the role of the Bcl-2 family of apoptosis regulators in this process. Interestingly, we found that acidic culture causes elevation of both Bcl-2 and Bcl-xL, while also attenuating glutamine starvation-induced elevation of p53-up-regulated modulator of apoptosis (PUMA) and Bim. We confirmed with knockdown studies that these shifts direct survival decisions during starvation and acidosis. Importantly, the promotion of a high anti- to pro-apoptotic Bcl-2 family member ratio by acidosis renders cells exquisitely sensitive to the Bcl-2/Bcl-xL antagonist ABT-737, suggesting that acidosis causes Bcl-2 family dependence. This dependence appears to be mediated, in part, by the acid-sensing G protein-coupled receptor, GPR65, via a MEK/ERK pathway.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Acidosis / genetics
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Acidosis / metabolism*
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Acidosis / pathology
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Animals
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Apoptosis Regulatory Proteins / genetics
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Apoptosis Regulatory Proteins / metabolism
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Apoptosis*
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Bcl-2-Like Protein 11
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Biphenyl Compounds / pharmacology
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Humans
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MAP Kinase Signaling System*
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Mice
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Nitrophenols / pharmacology
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Piperazines / pharmacology
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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Receptors, G-Protein-Coupled / genetics
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Receptors, G-Protein-Coupled / metabolism*
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Sulfonamides / pharmacology
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Tumor Suppressor Protein p53 / genetics
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Tumor Suppressor Protein p53 / metabolism
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Tumor Suppressor Proteins
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bcl-X Protein / antagonists & inhibitors
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bcl-X Protein / genetics
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bcl-X Protein / metabolism*
Substances
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ABT-737
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Apoptosis Regulatory Proteins
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BBC3 protein, human
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BCL2L1 protein, human
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BCL2L11 protein, human
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Bcl-2-Like Protein 11
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Bcl2l1 protein, mouse
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Bcl2l11 protein, mouse
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Biphenyl Compounds
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GPR65 protein, human
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GPR65 protein, mouse
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Membrane Proteins
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Nitrophenols
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PUMA protein, mouse
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Piperazines
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Proto-Oncogene Proteins
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Receptors, G-Protein-Coupled
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Sulfonamides
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TP53 protein, human
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Tumor Suppressor Protein p53
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Tumor Suppressor Proteins
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bcl-X Protein