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Byung Soo Kim
Korea University Anam Hospital
Corresponding Author
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Background: Chronic myeloid leukemia (CML) is a reciprocal translocation disorder driven by a breakpoint cluster region (BCR)-Abelson leukemia virus (ABL) fusion gene that stimulates abnormal tyrosine kinase activity. Tyrosine kinase inhibitors (TKIs) are effective in the treatment of Philadelphia chromosome (Ph)+ CML patients. However, the appearance of TKI-resistant CML cells is a hurdle in CML treatment. Therefore, it is necessary to identify novel treatments that could target a different mechanism than that of tyrosine kinases.
Methods: The study was designed to verify whether C-X-C chemokine receptor 2 (CXCR2) could be a novel target for TKI-resistant CML treatment. We examined CXCR2 ligands from CML patient samples and TKI-resistant CML cell lines. Then, we inhibited CXCR2 and examined the effects on cell proliferation and apoptosis using immunoblotting and flow cytometry. The CXCR2 inhibition effect was also confirmed using a mouse xenograft model with TKI-sensitive and -resistant CML cells.
Results: Interleukin 8 (IL-8), a CXCR2 ligand, was significantly increased in the bone marrow serum of initially diagnosed CML patients. CML cell lines expressed CXCR2, regardless of their sensitivity to TKIs. IL-8 stimulated CXCR2, mTOR, and c-Myc mRNA expression in CML cell lines. CXCR2 antagonists suppressed the proliferation of CML cells via cell cycle arrest in the G2/M phase. In addition, CXCR2 inhibition attenuated mTOR, c-Myc, and BCR-ABL expression, leading to CML cell apoptosis, irrespective of TKI responsiveness. Moreover, SB225002, a CXCR2 antagonist, caused higher cell death in CML cells than TKIs. Using a mouse xenograft model, we confirmed that SB225002 suppresses CML cells, with a prominent effect on TKI-resistant CML cells.
Conclusions: Taken together, our findings demonstrate that IL-8 is a prognostic factor to the progress of CML. Inhibiting the CXCR2-mTOR-c-Myc cascade is a promising therapeutic strategy to overcome TKI-sensitive and -insensitive CML. Thus, CXCR2 blockade is a novel therapeutic strategy to treat CML, and SB225002, a commercially available CXCR2 antagonist, might be a drug candidate to treat TKI-resistant CML.
Keywords
CXCR2, IL-8, mTOR, c-Myc, tyrosine kinase inhibitors, drug resistance
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This is a list of supplementary files associated with this preprint. Click to download.
- Additionalfile1.SupplementaryTable..docx
Table S1. BCR-ABL kinase mutations in TKI-resistant cells. Table S2. List of antibodies used in the human cytokine array. Table S3. List of PCR primer sequences used. Table S4. Characteristics of CML patients and healthy donors.
- Additionalfile2.Supplementaryfigure..docx
Fig. S1. TKI insensitivity in imatinib- and nilotinib-resistant CML cells. Fig. S2. Expression of Erk after SB225002 treatment. Fig. S3. Cell death in nilotinib-resistant K562 cells. Fig. S4. Effect of drugs on tumor size in a mouse xenograft model. Fig. S5. Expression of angiogenesis markers in a mouse xenograft model.
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research
Byung Soo Kim
Korea University Anam Hospital
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 25 Jan, 2021
No community comments so far
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Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Cancer Biology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Chronic myeloid leukemia (CML) is a reciprocal translocation disorder driven by a breakpoint cluster region (BCR)-Abelson leukemia virus (ABL) fusion gene that stimulates abnormal tyrosine kinase activity. Tyrosine kinase inhibitors (TKIs) are effective in the treatment of Philadelphia chromosome (Ph)+ CML patients. However, the appearance of TKI-resistant CML cells is a hurdle in CML treatment. Therefore, it is necessary to identify novel treatments that could target a different mechanism than that of tyrosine kinases.
Methods: The study was designed to verify whether C-X-C chemokine receptor 2 (CXCR2) could be a novel target for TKI-resistant CML treatment. We examined CXCR2 ligands from CML patient samples and TKI-resistant CML cell lines. Then, we inhibited CXCR2 and examined the effects on cell proliferation and apoptosis using immunoblotting and flow cytometry. The CXCR2 inhibition effect was also confirmed using a mouse xenograft model with TKI-sensitive and -resistant CML cells.
Results: Interleukin 8 (IL-8), a CXCR2 ligand, was significantly increased in the bone marrow serum of initially diagnosed CML patients. CML cell lines expressed CXCR2, regardless of their sensitivity to TKIs. IL-8 stimulated CXCR2, mTOR, and c-Myc mRNA expression in CML cell lines. CXCR2 antagonists suppressed the proliferation of CML cells via cell cycle arrest in the G2/M phase. In addition, CXCR2 inhibition attenuated mTOR, c-Myc, and BCR-ABL expression, leading to CML cell apoptosis, irrespective of TKI responsiveness. Moreover, SB225002, a CXCR2 antagonist, caused higher cell death in CML cells than TKIs. Using a mouse xenograft model, we confirmed that SB225002 suppresses CML cells, with a prominent effect on TKI-resistant CML cells.
Conclusions: Taken together, our findings demonstrate that IL-8 is a prognostic factor to the progress of CML. Inhibiting the CXCR2-mTOR-c-Myc cascade is a promising therapeutic strategy to overcome TKI-sensitive and -insensitive CML. Thus, CXCR2 blockade is a novel therapeutic strategy to treat CML, and SB225002, a commercially available CXCR2 antagonist, might be a drug candidate to treat TKI-resistant CML.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
This is a list of supplementary files associated with this preprint. Click to download.
- Additionalfile1.SupplementaryTable..docx
Table S1. BCR-ABL kinase mutations in TKI-resistant cells. Table S2. List of antibodies used in the human cytokine array. Table S3. List of PCR primer sequences used. Table S4. Characteristics of CML patients and healthy donors.
- Additionalfile2.Supplementaryfigure..docx
Fig. S1. TKI insensitivity in imatinib- and nilotinib-resistant CML cells. Fig. S2. Expression of Erk after SB225002 treatment. Fig. S3. Cell death in nilotinib-resistant K562 cells. Fig. S4. Effect of drugs on tumor size in a mouse xenograft model. Fig. S5. Expression of angiogenesis markers in a mouse xenograft model.
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