Combination with an Antisense Oligonucleotide Synergistically Improves the Antileukemic Efficacy of Erucylphospho-N,N,N -trimethylpropylammonium in Chronic Myeloid Leukemia Cell Lines

The aim of this study was to enhance the antileukemic efficacy of the alkylphosphocholine erucylphospho- N,N,N -trimethylpropylammonium (ErPC 3 ) in chronic myeloid leukemia (CML)-derived cell lines by a bcr -directed antisense oligonucleotide (ASO- bcr ). The mechanism was substantiated by Western blotting of the BCR-ABL expression level of CML cells, and the efficacy was substantiated by inhibition of colony formation compared with normal hematopoietic cells. The clonogenicity of K-562 cells expressing high levels of p210 BCR-ABL was inhibited significantly by the ASO- bcr (T/C%, 30; P < 0.05) but not by ErPC 3 (T/C%, 70). Combined sequential exposure to ErPC 3 and the ASO- bcr , however, inhibited synergistically colony growth (T/C%, 3; P < 0.01). The colony growth of BV-173 cells expressing lower levels of p210 BCR-ABL than K562 cells was inhibited to a greater extent by the ASO- bcr (T/C%, 15; P < 0.01). AR-230 cells that express high levels of p230 BCR-ABL showed an intermediate decrease in colony formation in response to the ASO- bcr (T/C%, 20; P < 0.05). BCR-ABL levels of BV-173, CML-T1, and LAMA-84 cells were reduced in response to the ASO- bcr , as evidenced by Western blot. However, K-562 and AR-230 cells showed reduced BCR-ABL expression only after repeated treatment. ErPC 3 and the ASO- bcr did not reduce colony formation (CFU-GM) of normal mouse bone marrow cells from long-term bone marrow cell cultures; instead, ErPC 3 stimulated colony formation ( P < 0.05) and did not induce chromosomal aberrations in mouse bone marrow. In conclusion, the combination of ErPC 3 with a suitable antisense oligonucleotide inhibited synergistically colony formation of CML cell lines without damaging normal cells and thus might have a bearing on the purging of autologous hematopoietic transplants in CML patients.