Polymethine Dye-Functionalized Nanoparticles for Targeting CML Stem Cells

Philipp Ernst,Adrian T Press,Mike Fischer,Vivien Günther,Christine Gräfe,Joachim H Clement,Thomas Ernst,Ulrich S Schubert,Jana Wotschadlo,Marc Lehmann,Christoph Enzensperger,Michael Bauer,Andreas Hochhaus

doi:10.1016/j.omto.2020.07.007

Abstract

In chronic myelogenous leukemia (CML), treatment with tyrosine kinase inhibitors (TKI) is unable to eradicate leukemic stem cells (LSC). Polymethine dye-functionalized nanoparticles can be internalized by specific cell types using transmembrane carrier proteins. In this study we investigated the uptake behavior of various polymethine dyes on leukemia cell lines and searched for carrier proteins that guide dye transport using RNA interference. The results show that the uptake of DY-635 is dependent on organic anion transport protein 1B3 (OATP1B3) in CML cells and immature myeloid precursor cells of CML patients. In contrast to nonspecific poly(lactide-co-glycolic acid) (PLGA) nanoparticle constructs, DY-635-functionalization of nanoparticles led to an uptake in CML cells. Investigation of these nanoparticles on bone marrow of CML patients showed a preferred uptake in LSC. The transcription of OATP1B3 is known to be induced under hypoxic conditions via the hypoxia-inducing factor 1 alpha (HIF1α), thus also in the stem cells niche. Since these cells have the potential to repopulate the bone marrow after CML treatment discontinuation, eliminating them by means of drug-loaded DY-635-functionalized PLGA nanoparticles deployed as a selective delivery system to LSC is highly relevant to the ongoing search for curative treatment options for CML patients.

Highlights

Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasia caused by the translocation t(9;22)(q34;q11) in the pluripotent hematopoietic stem cell with formation of a constitutively active BCR-ABL1 tyrosine kinase.[1]
DY-635 Functionalized poly(lactideco-glycolic acid) (PLGA) Nanoparticles Prefer Leukemic Stem Cells in chronic myelogenous leukemia (CML) Having demonstrated that functionalization of PLGA nanoparticles with DY-635 sensitizes nanoparticles for CML cells and that DY635 seems to be taken up predominantly by myeloid precursor cells in CML patients, we investigated further to determine whether DY635-functionalized PLGA nanoparticles could distinguish between hematopoietic stem cells (HSCs) (CD34+/CD38À/CD26À) and leukemic stem cells (LSC) (CD34+/CD38À/CD26+) in CML patients
We investigated whether the internalization of the dyes and the dye-functionalized nanoparticles is determined by certain carrier proteins

Summary

Introduction

Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasia caused by the translocation t(9;22)(q34;q11) in the pluripotent hematopoietic stem cell with formation of a constitutively active BCR-ABL1 tyrosine kinase.[1]. These cells have the potential to repopulate the bone marrow, leading to relapse.[2] Similar to normal hematopoietic stem cells (HSCs), LSCs have the ability to self-renew and establish a state of quiescence.[2,3] Since CML stem cells suppress BCR-ABL1 expression under treatment with TKIs, tyrosine kinase-independent mechanisms such as changes in mitochondrial metabolism, epigenetic modifications, and alterations of the transcriptional regulatory networks maintained by the stem cell niche are responsible for LSC persistence.[4,5] Imatinib and other TKIs targeting BCR-ABL1, as well as established chemotherapeutic drugs, inhibit cell proliferation, thereby inducing apoptosis They are not effective against non-proliferating progenitor cells and stem cells.[6] New, innovative and gentler treatment strategies to eliminate the remaining CML stem cells must be developed to completely cure CML patients who achieve a good molecular response after initial TKI therapy

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