Determinants of sensitivity of human T-cell leukemia CCRF-CEM cells to immucillin-H

Min Huang, Yanhong Wang, Jingjin Gu, Jing Yang, Karen Noel, Beverly S. Mitchell, Vern L. Schramm, Lee M. Graves

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Immucillin-H (BCX-1777, forodesine) is a transition state analogue and potent inhibitor of PNP that shows promise as a specific agent against activated human T-cells and T-cell leukemias. The immunosuppressive or antileukemic effects of Immucillin-H (ImmH) in cultured cells require co-administration with deoxyguanosine (dGuo) to attain therapeutic levels of intracellular dGTP. In this study we investigated the requirements for sensitivity and resistance to ImmH and dGuo. 3H-ImmH transport assays demonstrated that the equilibrative nucleoside transporters (ENT1 and ENT2) facilitated the uptake of ImmH in human leukemia CCRF-CEM cells whereas 3H-dGuo uptake was primarily dependent upon concentrative nucleoside transporters (CNTs). Analysis of lysates from ImmH-resistant CCRF-CEM-AraC-8D cells demonstrated undetectable deoxycytidine kinase (dCK) activity, suggesting that dCK and not deoxyguanosine kinase (dGK) was the rate-limiting enzyme for phosphorylation of dGuo in these cells. Examination of ImmH cytotoxicity in a hypoxanthine-guanine phosphoribosyltransferase (HGPRT)-deficient cell line CCRF-CEM-AraC-8C, demonstrated enhanced sensitivity to low concentrations of ImmH and dGuo. RT-PCR and sequencing of HGPRT from the HGPRT-deficient CCRF-CEM-AraC-8C cells identified an Exon 8 deletion mutation in this enzyme. Thus these studies show that specific nucleoside transporters are required for ImmH cytotoxicity and predict that ImmH may be more cytotoxic to 6-thioguanine (6-TG) or 6-thiopurine-resistant leukemia cells caused by HGPRT deficiency.

Original languageEnglish (US)
Pages (from-to)1268-1278
Number of pages11
JournalLeukemia Research
Issue number8
StatePublished - Aug 2008


  • Deoxycytidine kinase
  • Deoxyguanosine
  • Hypoxanthine-guanine phosphoribosyltransferase
  • Immucillin
  • Nucleoside transporters
  • T-cell leukemia

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Cancer Research


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