Analysis of gene expression profiles in an imatinib-resistant cell line, KCL22/SR.
The BCR/ABL tyrosine kinase inhibitor, imatinib, has shown substantial effects in blast crises of chronic myelogenous leukemia. However, most patients relapse after an initial clinical response, indicating that drug resistance is a major problem for patients being treated with imatinib. In this study, we generated a new imatinib-resistant BCR/ABL-positive cell line, KCL22/SR. The 50% inhibitory concentration of imatinib was 11-fold higher in KCL22/SR than in the imatinib-sensitive parental cell line, KCL22. However, KCL22/SR showed no mutations in the BCR/ABL gene and no increase in the levels of BCR/ABL protein and P-glycoprotein. Furthermore, the level of phosphorylated BCR/ABL protein was suppressed by imatinib treatment, suggesting that mechanisms independent of BCR/ABL signaling are involved in the imatinib resistance in KCL22/SR cells. DNA microarray analyses demonstrated that the signal transduction-related molecules, RAS p21 protein activator and RhoA, which could affect Ras signaling, and a surface tumor antigen, L6, were upregulated, while c-Myb and activin A receptor were downregulated in KCL22/SR cells. Furthermore, imatinib treatment significantly suppressed the level of phosphorylated p44/42 in KCL22 cells but not in KCL22/SR cells, even when BCR/ABL was inhibited by imatinib. These results suggest that various mechanisms, including disturbance of Ras-mitogen-activated protein kinase signaling, are involved in imatinib resistance.
Ohmine
Ken
K
Divisions of Hematology, Cell Transplantation and Transfusion, and Functional Genomics, Jichi Medical School, Tochigi, Japan.
Nagai
Tadashi
T
Tarumoto
Takahisa
T
Miyoshi
Takuji
T
Muroi
Kazuo
K
Mano
Hiroyuki
H
Komatsu
Norio
N
Takaku
Fumimaro
F
Ozawa
Keiya
K
D000970:Antineoplastic Agents / Q000494:pharmacology*; D001549:Benzamides; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D016044:Fusion Proteins, bcr-abl / Q000187:drug effects / Q000235:genetics; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000235:genetics* / Q000276:immunology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D055502:Secondary Prevention; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D018631:ras Proteins / Q000187:drug effects / Q000378:metabolism
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins