Polo-like kinase 1 (Plk1) as a novel drug target in chronic myeloid leukemia: overriding imatinib resistance with the Plk1 inhibitor BI 2536.
In most patients with chronic myeloid leukemia (CML), the disease can be kept under control using the BCR/ABL kinase inhibitor imatinib. Nevertheless, resistance or intolerance to imatinib and other BCR/ABL inhibitors may occur during therapy. Therefore, CML research is focusing on novel targets and targeted drugs. Polo-like kinase 1 (Plk1) is a serine/threonine kinase that plays an essential role in mitosis. In this study, we examined the expression of Plk1 in CML cells and its potential role as a therapeutic target. Plk1 was found to be expressed in phosphorylated form in the CML cell line K562 as well as in primary CML cells in all patients tested. Inhibition of BCR/ABL by imatinib or nilotinib (AMN107) led to decreased expression of the Plk1 protein in CML cells, suggesting that BCR/ABL promotes Plk1 generation. Silencing of Plk1 in CML cells by a small interfering RNA approach was followed by cell cycle arrest and apoptosis. Furthermore, the Plk1-targeting drug BI 2536 was found to inhibit proliferation of imatinib-sensitive and imatinib-resistant CML cells, including leukemic cells, carrying the T315 mutation of BCR/ABL with reasonable IC(50) values (1-50 nmol/L). The growth-inhibitory effects of BI 2536 on CML cells were found to be associated with cell cycle arrest and apoptosis. Moreover, BI 2536 was found to synergize with imatinib and nilotinib in producing growth inhibition in CML cells. In conclusion, Plk1 is expressed in CML cells and may represent a novel, interesting target in imatinib-sensitive and imatinib-resistant CML.
Department of Internal Medicine I, Division of Hematology and Hemostaseology, Institute of Immunology, Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, A-1090 Vienna, Austria.
Karoline V
KV
Gleixner
Veronika
V
Ferenc
Barbara
B
Peter
Alexander
A
Gruze
Renata A
RA
Meyer
Emir
E
Hadzijusufovic
Sabine
S
Cerny-Reiterer
Matthias
M
Mayerhofer
Winfried F
WF
Pickl
Christian
C
Sillaber
Peter
P
Valent
D000293:Adolescent; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000627:therapeutic use; D001549:Benzamides; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D016503:Drug Delivery Systems / Q000379:methods; D004353:Drug Evaluation, Preclinical; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000235:genetics / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D011621:Pteridines / Q000008:administration & dosage / Q000627:therapeutic use*; D011743:Pyrimidines / Q000627:therapeutic use*; D000097869:Polo-Like Kinase 1
D001549:Benzamides; D018797:Cell Cycle Proteins; D016044:Fusion Proteins, bcr-abl; D000068877:Imatinib Mesylate; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011621:Pteridines; D011743:Pyrimidines; D000097869:Polo-Like Kinase 1; C518477:BI 2536