TY - JOUR
T1 - Cellular uptake and intracellular levels of the Bcl-2 antisense G3139 in cultured cells and treated patients with acute myeloid leukemia
AU - Dai, Guowei
AU - Chan, Kenneth K.
AU - Liu, Shujun
AU - Hoyt, Dale
AU - Whitman, Susan
AU - Klisovic, Marko
AU - Shen, Tiansheng
AU - Caligiuri, Michael A.
AU - Byrd, John
AU - Grever, Michael
AU - Marcucci, Guido
PY - 2005/4/15
Y1 - 2005/4/15
N2 - Purpose: Down-regulation of Bcl-2 by the antisense G3139, currently under clinical evaluations, could restore chemosensitivity in otherwise resistant malignant cells. To date, the mechanism of intracellular accumulation of G3139 following in vivo administration remains to be elucidated. This study aimed to assess whether detectable intracellular concentrations of G3139 are achievable in vivo and how these relate to Bcl-2 down-regulation. Experimental Design: Cellular uptake of G3139 was studied in leukemia myeloid cell lines and blasts collected from treated patients using a newly developed, novel, and highly sensitive ELISA-based assay. Real-time reverse transcription-PCR was used to quantify Bcl-2 mRNA changes in treated cells. Results: The assay was fully validated and showed a limit of quantification of 50 pmol/L. When exposed to 0.33 to 10 μmol/L G3139, K562 cells exhibited intracellular concentrations in the range of 2.1 to 11.4 pmol/mg protein. When G3139 was delivered with cationic lipids, a 10- to 25-fold increase of the intracellular concentrations was observed. There was an accumulation of G3139 in the nuclei, and the ratio of nucleus to cytoplasm was increased 7-fold by cationic lipids. Intracellular concentrations of G3139 were correlated with Bcl-2 mRNA down-regulation. Robust intracellular concentrations of G3139 were achieved in vivo in bone marrow (range, 3.4-40.6 pmol/mg protein) and peripheral blood mononuclear cells (range, 0.47-19.4 pmol/mg protein) from acute myeloid leukemia patients treated with G3139. Conclusions: This is the first evidence that measurable intracellular levels of G3139 are achievable in vivo in acute myeloid leukemia patients and that Bcl-2 down-regulation is likely to depend on the achievable intracellular concentrations rather than on plasma concentrations.
AB - Purpose: Down-regulation of Bcl-2 by the antisense G3139, currently under clinical evaluations, could restore chemosensitivity in otherwise resistant malignant cells. To date, the mechanism of intracellular accumulation of G3139 following in vivo administration remains to be elucidated. This study aimed to assess whether detectable intracellular concentrations of G3139 are achievable in vivo and how these relate to Bcl-2 down-regulation. Experimental Design: Cellular uptake of G3139 was studied in leukemia myeloid cell lines and blasts collected from treated patients using a newly developed, novel, and highly sensitive ELISA-based assay. Real-time reverse transcription-PCR was used to quantify Bcl-2 mRNA changes in treated cells. Results: The assay was fully validated and showed a limit of quantification of 50 pmol/L. When exposed to 0.33 to 10 μmol/L G3139, K562 cells exhibited intracellular concentrations in the range of 2.1 to 11.4 pmol/mg protein. When G3139 was delivered with cationic lipids, a 10- to 25-fold increase of the intracellular concentrations was observed. There was an accumulation of G3139 in the nuclei, and the ratio of nucleus to cytoplasm was increased 7-fold by cationic lipids. Intracellular concentrations of G3139 were correlated with Bcl-2 mRNA down-regulation. Robust intracellular concentrations of G3139 were achieved in vivo in bone marrow (range, 3.4-40.6 pmol/mg protein) and peripheral blood mononuclear cells (range, 0.47-19.4 pmol/mg protein) from acute myeloid leukemia patients treated with G3139. Conclusions: This is the first evidence that measurable intracellular levels of G3139 are achievable in vivo in acute myeloid leukemia patients and that Bcl-2 down-regulation is likely to depend on the achievable intracellular concentrations rather than on plasma concentrations.
UR - http://www.scopus.com/inward/record.url?scp=20244382115&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=20244382115&partnerID=8YFLogxK
U2 - 10.1158/1078-0432.CCR-04-1505
DO - 10.1158/1078-0432.CCR-04-1505
M3 - Article
C2 - 15837754
AN - SCOPUS:20244382115
SN - 1078-0432
VL - 11
SP - 2998
EP - 3008
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 8
ER -