Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.

Thiamine-dependent enzymes (TDEs) control metabolic pathways that are frequently altered in cancer and therefore present cancer-relevant targets. We have previously shown that the recombinant enzyme thiaminase cleaves and depletes intracellular thiamine, has growth inhibitory activity against leukem...

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Autores principales:	Shuqian Liu, Sumitra Miriyala, Mignon A Keaton, Craig T Jordan, Christina Wiedl, Daret K St Clair, Jeffrey A Moscow
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2014
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/f79d5967ecbf4b308fbfbda866487bd0
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spelling	oai:doaj.org-article:f79d5967ecbf4b308fbfbda866487bd02021-11-18T08:37:37ZMetabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.1932-620310.1371/journal.pone.0085702https://doaj.org/article/f79d5967ecbf4b308fbfbda866487bd02014-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24454921/?tool=EBIhttps://doaj.org/toc/1932-6203Thiamine-dependent enzymes (TDEs) control metabolic pathways that are frequently altered in cancer and therefore present cancer-relevant targets. We have previously shown that the recombinant enzyme thiaminase cleaves and depletes intracellular thiamine, has growth inhibitory activity against leukemia and breast cancer cell lines, and that its growth inhibitory effects were reversed in leukemia cell lines by rapamycin. Now, we first show further evidence of thiaminase therapeutic potential by demonstrating its activity against breast and leukemia xenografts, and against a primary leukemia xenograft. We therefore further explored the metabolic effects of thiaminase in combination with rapamycin in leukemia and breast cell lines. Thiaminase decreased oxygen consumption rate and increased extracellular acidification rate, consistent with the inhibitory effect of acute thiamine depletion on the activity of the TDEs pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes; these effects were reversed by rapamycin. Metabolomic studies demonstrated intracellular thiamine depletion and the presence of the thiazole cleavage product in thiaminase-treated cells, providing validation of the experimental procedures. Accumulation of ribose and ribulose in both cell lines support the thiaminase-mediated suppression of the TDE transketolase. Interestingly, thiaminase suppression of another TDE, branched chain amino ketoacid dehydrogenase (BCKDH), showed very different patterns in the two cell lines: in RS4 leukemia cells it led to an increase in BCKDH substrates, and in MCF-7 breast cancer cells it led to a decrease in BCKDH products. Immunoblot analyses showed corresponding differences in expression of BCKDH pathway enzymes, and partial protection of thiaminase growth inhibition by gabapentin indicated that BCKDH inhibition may be a mechanism of thiaminase-mediated toxicity. Surprisingly, most of thiaminase-mediated metabolomic effects were also reversed by rapamycin. Thus, these studies demonstrate that acute intracellular thiamine depletion by recombinant thiaminase results in metabolic changes in thiamine-dependent metabolism, and demonstrate a previously unrecognized role of mTOR signaling in the regulation of thiamine-dependent metabolism.Shuqian LiuSumitra MiriyalaMignon A KeatonCraig T JordanChristina WiedlDaret K St ClairJeffrey A MoscowPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 9, Iss 1, p e85702 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Shuqian Liu Sumitra Miriyala Mignon A Keaton Craig T Jordan Christina Wiedl Daret K St Clair Jeffrey A Moscow Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.
description	Thiamine-dependent enzymes (TDEs) control metabolic pathways that are frequently altered in cancer and therefore present cancer-relevant targets. We have previously shown that the recombinant enzyme thiaminase cleaves and depletes intracellular thiamine, has growth inhibitory activity against leukemia and breast cancer cell lines, and that its growth inhibitory effects were reversed in leukemia cell lines by rapamycin. Now, we first show further evidence of thiaminase therapeutic potential by demonstrating its activity against breast and leukemia xenografts, and against a primary leukemia xenograft. We therefore further explored the metabolic effects of thiaminase in combination with rapamycin in leukemia and breast cell lines. Thiaminase decreased oxygen consumption rate and increased extracellular acidification rate, consistent with the inhibitory effect of acute thiamine depletion on the activity of the TDEs pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes; these effects were reversed by rapamycin. Metabolomic studies demonstrated intracellular thiamine depletion and the presence of the thiazole cleavage product in thiaminase-treated cells, providing validation of the experimental procedures. Accumulation of ribose and ribulose in both cell lines support the thiaminase-mediated suppression of the TDE transketolase. Interestingly, thiaminase suppression of another TDE, branched chain amino ketoacid dehydrogenase (BCKDH), showed very different patterns in the two cell lines: in RS4 leukemia cells it led to an increase in BCKDH substrates, and in MCF-7 breast cancer cells it led to a decrease in BCKDH products. Immunoblot analyses showed corresponding differences in expression of BCKDH pathway enzymes, and partial protection of thiaminase growth inhibition by gabapentin indicated that BCKDH inhibition may be a mechanism of thiaminase-mediated toxicity. Surprisingly, most of thiaminase-mediated metabolomic effects were also reversed by rapamycin. Thus, these studies demonstrate that acute intracellular thiamine depletion by recombinant thiaminase results in metabolic changes in thiamine-dependent metabolism, and demonstrate a previously unrecognized role of mTOR signaling in the regulation of thiamine-dependent metabolism.
format	article
author	Shuqian Liu Sumitra Miriyala Mignon A Keaton Craig T Jordan Christina Wiedl Daret K St Clair Jeffrey A Moscow
author_facet	Shuqian Liu Sumitra Miriyala Mignon A Keaton Craig T Jordan Christina Wiedl Daret K St Clair Jeffrey A Moscow
author_sort	Shuqian Liu
title	Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.
title_short	Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.
title_full	Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.
title_fullStr	Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.
title_full_unstemmed	Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.
title_sort	metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.
publisher	Public Library of Science (PLoS)
publishDate	2014
url	https://doaj.org/article/f79d5967ecbf4b308fbfbda866487bd0
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Metabolic effects of acute thiamine depletion are reversed by rapamycin in breast and leukemia cells.

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