Clinical experience with tyrosine kinase inhibitors (TKIs) over the past two decades has shown that, despite the apparent therapeutic benefit, nearly 30% of patients with chronic myelogenous leukemia (CML) display primary resistance or intolerance to TKIs, and approximately 25% of those treated are forced to switch TKIs at least once during therapy due to acquired resistance. Safe and effective treatment modalities targeting leukemic clones that escape TKI therapy could hence be game changers in the professional management of these patients. Here, we aimed to investigate the efficacy of a novel therapeutic oligonucleotide of unconventional design, called ASP210, to reduce BCR-ABL1 mRNA levels in TKI-resistant CML cells, with the assumption of inducing their apoptosis. Imatinib- and dasatinib-resistant sublines of BCR-ABL1-positive MOLM-7 and CML-T1 cells were established and exposed to 0.25 and 2.5 µM ASP210 for 10 days. RT-qPCR showed a remarkable reduction of the target mRNA level by >99% after a single application. Cell viability was monitored daily by trypan blue staining. In response to the lack of driver oncoprotein BCR-ABL1, TKI-resistant CML cells underwent apoptosis regardless of the presence of the clinically relevant T315I mutation by day 5 after redosing with ASP210. The effect was selective for cancer cells, indicating a favorable safety profile for this therapeutic modality. Furthermore, the spontaneous uptake and high intracellular concentrations of ASP210 suggest its potential to be effective at relatively low doses. The present findings suggest that ASP210 is a promising therapeutic avenue for patients with CML who fail to respond to TKI therapy.NEW & NOTEWORTHY Effective treatment modalities targeting leukemic clones that escape tyrosine kinase inhibitor (TKI) therapy could be game changers in the professional management of patients displaying primary resistance, intolerance, or acquired resistance to TKIs. Although delivering authentic innovations today is more complex than ever, we developed a highly potent and safe oligonucleotide-based modality against BCR-ABL1 mRNA named ASP210 that effectively induces cell death in BCR-ABL1-positive TKI-resistant cells while sparing BCR-ABL1-negative healthy cells.

• Klíčová slova
• BCR-ABL1, chronic myelogenous leukemia, oligonucleotide therapeutics, resistance to therapy, tyrosine kinase inhibitors,
• MeSH
• antitumorózní látky farmakologie   MeSH
• apoptóza * účinky léků   MeSH
• bcr-abl fúzové proteiny * genetika   antagonisté a inhibitory   metabolismus   MeSH
• chemorezistence * účinky léků   MeSH
• chronická myeloidní leukemie * farmakoterapie   genetika   patologie   MeSH
• dasatinib farmakologie   MeSH
• imatinib mesylát * farmakologie   terapeutické užití   MeSH
• inhibitory proteinkinas * farmakologie   MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• oligonukleotidy * farmakologie   MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antitumorózní látky MeSH
• bcr-abl fúzové proteiny * MeSH
• BCR-ABL1 fusion protein, human MeSH Prohlížeč
• dasatinib MeSH
• imatinib mesylát * MeSH
• inhibitory proteinkinas * MeSH
• messenger RNA MeSH
• oligonukleotidy * MeSH

Chronic myelogenous leukemia (CML) is a myeloproliferative disease characterized by the BCR-ABL oncogene. Despite the high performance of treatment with tyrosine kinase inhibitors (TKI), about 30% of patients develop resistance to the therapy. To improve the outcomes, identification of new targets of treatment is needed. Here, we explored the Casein Kinase 2 (CK2) as a potential target for CML therapy. Previously, we detected increased phosphorylation of HSP90β Serine 226 in patients non-responding to TKIs imatinib and dasatinib. This site is known to be phosphorylated by CK2, which was also linked to CML resistance to imatinib. In the present work, we established six novel imatinib- and dasatinib-resistant CML cell lines, all of which had increased CK2 activation. A CK2 inhibitor, CX-4945, induced cell death of CML cells in both parental and resistant cell lines. In some cases, CK2 inhibition also potentiated the effects of TKI on the cell metabolic activity. No effects of CK2 inhibition were observed in normal mononuclear blood cells from healthy donors and BCR-ABL negative HL60 cell line. Our data indicate that CK2 kinase supports CML cell viability even in cells with different mechanisms of resistance to TKI, and thus represents a potential target for treatment.

• MeSH
• apoptóza MeSH
• bcr-abl fúzové proteiny metabolismus   MeSH
• buněčná smrt MeSH
• chemorezistence MeSH
• chronická myeloidní leukemie * farmakoterapie   MeSH
• dasatinib farmakologie   MeSH
• imatinib mesylát farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• inhibitory tyrosinkinasy MeSH
• kaseinkinasa II * MeSH
• lidé MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bcr-abl fúzové proteiny MeSH
• dasatinib MeSH
• imatinib mesylát MeSH
• inhibitory proteinkinas MeSH
• inhibitory tyrosinkinasy MeSH
• kaseinkinasa II * MeSH

The lysosomal sequestration of hydrophobic weak-base anticancer drugs is one proposed mechanism for the reduced availability of these drugs at target sites, resulting in a marked decrease in cytotoxicity and consequent resistance. While this subject is receiving increasing emphasis, it is so far only in laboratory experiments. Imatinib is a targeted anticancer drug used to treat chronic myeloid leukaemia (CML), gastrointestinal stromal tumours (GISTs), and a number of other malignancies. Its physicochemical properties make it a typical hydrophobic weak-base drug that accumulates in the lysosomes of tumour cells. Further laboratory studies suggest that this might significantly reduce its antitumor efficacy. However, a detailed analysis of published laboratory studies shows that lysosomal accumulation cannot be considered a clearly proven mechanism of resistance to imatinib. Second, more than 20 years of clinical experience with imatinib has revealed a number of resistance mechanisms, none of which is related to its accumulation in lysosomes. This review focuses on the analysis of salient evidence and raises a fundamental question about the significance of lysosomal sequestration of weak-base drugs in general as a possible resistance mechanism both in clinical and laboratory settings.

• Klíčová slova
• STI571, cancer, drug resistance mechanisms, hydrophobic weak-base drugs, lysosomal drug sequestration, tyrosine kinase inhibitors,
• MeSH
• antitumorózní látky * terapeutické užití   MeSH
• chronická myeloidní leukemie * farmakoterapie   MeSH
• imatinib mesylát terapeutické užití   MeSH
• lidé MeSH
• lyzozomy MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• antitumorózní látky * MeSH
• imatinib mesylát MeSH