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Differences between intrinsic and acquired nucleoside analogue resistance in acute myeloid leukaemia cells

Rothenburger, Tamara, Thomas, Dominique, Schreiber, Yannick, Wratil, Paul R., Pflantz, Tamara, Knecht, Kirsten, Digianantonio, Katie, Temple, Joshua, Schneider, Constanze, Baldauf, Hanna-Mari, and others. (2021) Differences between intrinsic and acquired nucleoside analogue resistance in acute myeloid leukaemia cells. Journal of Experimental & Clinical Cancer Research, 40 . Article Number 317. E-ISSN 1756-9966. (doi:10.1186/s13046-021-02093-4) (KAR id:91275)



SAMHD1 mediates resistance to anti-cancer nucleoside analogues, including cytarabine, decitabine, and nelarabine that are commonly used for the treatment of leukaemia, through cleavage of their triphosphorylated forms. Hence, SAMHD1 inhibitors are promising candidates for the sensitisation of leukaemia cells to nucleoside analogue-based therapy. Here, we investigated the effects of the cytosine analogue CNDAC, which has been proposed to be a SAMHD1 inhibitor, in the context of SAMHD1.


CNDAC was tested in 13 acute myeloid leukaemia (AML) cell lines, in 26 acute lymphoblastic leukaemia (ALL) cell lines, ten AML sublines adapted to various antileukaemic drugs, 24 single cell-derived clonal AML sublines, and primary leukaemic blasts from 24 AML patients. Moreover, 24 CNDAC-resistant sublines of the AML cell lines HL-60 and PL-21 were established. The SAMHD1 gene was disrupted using CRISPR/Cas9 and SAMHD1 depleted using RNAi, and the viral Vpx protein. Forced DCK expression was achieved by lentiviral transduction. SAMHD1 promoter methylation was determined by PCR after treatment of genomic DNA with the methylation-sensitive HpaII endonuclease. Nucleoside (analogue) triphosphate levels were determined by LC-MS/MS. CNDAC interaction with SAMHD1 was analysed by an enzymatic assay and by crystallisation.


Although the cytosine analogue CNDAC was anticipated to inhibit SAMHD1, SAMHD1 mediated intrinsic CNDAC resistance in leukaemia cells. Accordingly, SAMHD1 depletion increased CNDAC triphosphate (CNDAC-TP) levels and CNDAC toxicity. Enzymatic assays and crystallisation studies confirmed CNDAC-TP to be a SAMHD1 substrate. In 24 CNDAC-adapted acute myeloid leukaemia (AML) sublines, resistance was driven by DCK (catalyses initial nucleoside phosphorylation) loss. CNDAC-adapted sublines displayed cross-resistance only to other DCK substrates (e.g. cytarabine, decitabine). Cell lines adapted to drugs not affected by DCK or SAMHD1 remained CNDAC sensitive. In cytarabine-adapted AML cells, increased SAMHD1 and reduced DCK levels contributed to cytarabine and CNDAC resistance.


Intrinsic and acquired resistance to CNDAC and related nucleoside analogues are driven by different mechanisms. The lack of cross-resistance between SAMHD1/ DCK substrates and non-substrates provides scope for next-line therapies after treatment failure.

Item Type: Article
DOI/Identification number: 10.1186/s13046-021-02093-4
Uncontrolled keywords: Leukemia, Acute myeloid leukemia, Acute lymphoblastic leukemia, CNDAC, Sapacitabine, SAMHD1, DCK, Intrinsic resistance, Acquired resistance
Subjects: R Medicine > RC Internal medicine > RC254 Neoplasms. Tumors. Oncology
R Medicine > RM Therapeutics. Pharmacology
Divisions: Divisions > Division of Natural Sciences > Biosciences
Depositing User: Martin Michaelis
Date Deposited: 02 Nov 2021 16:20 UTC
Last Modified: 14 Nov 2022 23:13 UTC
Resource URI: (The current URI for this page, for reference purposes)

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