Effect of major tumor metabolites on the release of doxorubicin from Doxil – implications for precision nanomedicine

Lisa Silverman, Yechezkel Barenholz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Our previous studies demonstrate that ammonia induces doxorubicin release from Doxil® in a concentration-dependent manner. Because ammonia that results from glutaminolysis is continuously generated in tumors at high enough concentration to induce doxorubicin release of Doxil in tumors, this may explain why doxorubicin release in interstitial tumor fluids is much faster and higher than in the plasma, in which release is minimal. This unique activity of tumor ammonia may explain, at least in part, the therapeutic efficacy of Doxil, which in practice does not release doxorubicin in animal and human plasma. Our current study aims to evaluate if tumor-specific metabolites other than ammonia, such as lactate and pyruvate, are also involved in doxorubicin release from Doxil. Also, we studied levels of ammonia in other mouse organs. Our data shows that these other metabolites do not affect doxorubicin release. Furthermore, using the Metabolic gEne RApid Visualizer database (MERAV), we computationally explored the relationships of glutaminase (GLS) 1 and 2, glutamate dehydrogenase (GLUD)l and 2, as well as glutamine transporters regulating the glutaminolysis levels found in different cancers. These glutaminolysis levels could not be achieved without the upregulation of glutamine transporters. Indeed, our queries to MERAV showed that SLC38A1, SLC38A2, and especially SLC38A6, are up-regulated in cancerous tissues. We discuss how the information on the upregulation of enzymes related to glutaminolysis could be used for “precision medicine” to determine if Doxil is an appropriate choice for a specific cancer patient. Our computational exploration shows that glutaminolysis is heightened in some cancerous tissues as compared to their noimal counterparts, but not in all cases. It would be possible and perhaps advantageous to test individual patient tissues to determine glutaminolysis, and therefore likely, ammonium levels in cancerous tissues, and to use this to ascertain if Doxil would be a good treatment choice.

Original languageEnglish
Pages (from-to)699-708
Number of pages10
JournalPrecision Nanomedicine
Volume3
Issue number4
DOIs
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2020, Andover House, Inc.. All rights reserved.

Keywords

  • ammonia
  • Doxil
  • glutaminolysis
  • nanoparticles
  • tumor microenvironment

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