MATE1 REGULATES CELLULAR UPTAKE AND SENSITIVITY TO IMATINIB IN CML PATIENTS
(Abstract release date: 05/19/16)
EHA Library. Edemir B. 06/09/16; 132643; E1094
Dr. Bayram Edemir
Contributions
Contributions
Abstract
Abstract: E1094
Type: Eposter Presentation
Background
Imatinib is highly effective in the treatment of chronic myeloid leukemia (CML). Up to 30% of CML patients treated with Imatinib as a first-line therapy experience treatment failure. The response rate varies within different stages of the disease. Besides other mechanisms of resistance such as mutations in the Bcr-Abl1 fusion gene, the transport of Imatinib into its target cells has been proposed to be crucial for its effectiveness. As an organic cation, Imatinib has to be actively translocated across the cell membrane. Though some studies suggested a critical role of the organic cation transporter 1 (OCT1) in regulating Imatinib efficacy, other studies could not confirm these findings. Although OCT1 is generally capable to transport Imatinib, it might have minor relevance under clinical conditions. We recently demonstrated that the multidrug and toxin extrusion protein 1 (MATE1) accepts Imatinib as a substrate.
Aims
In this study, we focused on transporters, which are relevant for Imatinib uptake and investigated their expression pattern in PBMCs and if they contribute to Imatinib uptake and expression in samples from CML patients or CML cell lines.
Methods
We used PBMC from 6 healthy volunteers and transporter expression profile was analyzed by qPCR and intracellular Imatinib accumulation was quantified by HPLC-UV using stably transfected HEK cells. To assess Imatinib dependent biologic effects on MATE1 expression, activity of bcr-Abl1 protein was detected by Western blot analysis using anti-phospho ABL and GAPDH antibody. To address the clinical significance of MATE1 on the Imatinib therapy in CML, we evaluated the clonal growth of the immortalized CML cell line K562 cells stably transduced with shRNA against MATE1 in methylcellulose medium supplemented with Imatinib.
Results
The results showed that Imatinib uptake was significantly increased in OCT1, OCT2- and MATE1 expressing HEK-cells. We found that the transport via MATE1 is clinically highly relevant as represented by a remarkably high quotient for therapy regimes. This is supported by qPCR expression of MATE1 in 31 patients with Bcr-Abl1 major transcript (p210) positive CML.The mRNA expression of potential Imatinib transporters in PBMC of healthy volunteers as well as in K562 cells showed that in both cell types OCT1, OCT2 and MATE1 were detected at similar levels comparable to the Imatinib uptake rate into these cells. Inhibitor studies showed that MATE1 plays an important role in Imatinib accumulation. In patients, Imatinib non-responders showed a significantly lower MATE1 expression than Imatinib responders and we found a correlation between MATE1 transporter expression and clinical response to Imatinib treatment, suggesting that MATE1 might enable to predict whether CML patients are likely to respond to Imatinib therapy.
Conclusion
Thus, we identify MATE1 as the main transporter for the Imatinib dependent therapeutic response of CML patients.
Session topic: E-poster
Keyword(s): Chronic myeloid leukemia, Drug sensitivity, Tyrosine kinase inhibitor
Type: Eposter Presentation
Background
Imatinib is highly effective in the treatment of chronic myeloid leukemia (CML). Up to 30% of CML patients treated with Imatinib as a first-line therapy experience treatment failure. The response rate varies within different stages of the disease. Besides other mechanisms of resistance such as mutations in the Bcr-Abl1 fusion gene, the transport of Imatinib into its target cells has been proposed to be crucial for its effectiveness. As an organic cation, Imatinib has to be actively translocated across the cell membrane. Though some studies suggested a critical role of the organic cation transporter 1 (OCT1) in regulating Imatinib efficacy, other studies could not confirm these findings. Although OCT1 is generally capable to transport Imatinib, it might have minor relevance under clinical conditions. We recently demonstrated that the multidrug and toxin extrusion protein 1 (MATE1) accepts Imatinib as a substrate.
Aims
In this study, we focused on transporters, which are relevant for Imatinib uptake and investigated their expression pattern in PBMCs and if they contribute to Imatinib uptake and expression in samples from CML patients or CML cell lines.
Methods
We used PBMC from 6 healthy volunteers and transporter expression profile was analyzed by qPCR and intracellular Imatinib accumulation was quantified by HPLC-UV using stably transfected HEK cells. To assess Imatinib dependent biologic effects on MATE1 expression, activity of bcr-Abl1 protein was detected by Western blot analysis using anti-phospho ABL and GAPDH antibody. To address the clinical significance of MATE1 on the Imatinib therapy in CML, we evaluated the clonal growth of the immortalized CML cell line K562 cells stably transduced with shRNA against MATE1 in methylcellulose medium supplemented with Imatinib.
Results
The results showed that Imatinib uptake was significantly increased in OCT1, OCT2- and MATE1 expressing HEK-cells. We found that the transport via MATE1 is clinically highly relevant as represented by a remarkably high quotient for therapy regimes. This is supported by qPCR expression of MATE1 in 31 patients with Bcr-Abl1 major transcript (p210) positive CML.The mRNA expression of potential Imatinib transporters in PBMC of healthy volunteers as well as in K562 cells showed that in both cell types OCT1, OCT2 and MATE1 were detected at similar levels comparable to the Imatinib uptake rate into these cells. Inhibitor studies showed that MATE1 plays an important role in Imatinib accumulation. In patients, Imatinib non-responders showed a significantly lower MATE1 expression than Imatinib responders and we found a correlation between MATE1 transporter expression and clinical response to Imatinib treatment, suggesting that MATE1 might enable to predict whether CML patients are likely to respond to Imatinib therapy.
Conclusion
Thus, we identify MATE1 as the main transporter for the Imatinib dependent therapeutic response of CML patients.
Session topic: E-poster
Keyword(s): Chronic myeloid leukemia, Drug sensitivity, Tyrosine kinase inhibitor
Abstract: E1094
Type: Eposter Presentation
Background
Imatinib is highly effective in the treatment of chronic myeloid leukemia (CML). Up to 30% of CML patients treated with Imatinib as a first-line therapy experience treatment failure. The response rate varies within different stages of the disease. Besides other mechanisms of resistance such as mutations in the Bcr-Abl1 fusion gene, the transport of Imatinib into its target cells has been proposed to be crucial for its effectiveness. As an organic cation, Imatinib has to be actively translocated across the cell membrane. Though some studies suggested a critical role of the organic cation transporter 1 (OCT1) in regulating Imatinib efficacy, other studies could not confirm these findings. Although OCT1 is generally capable to transport Imatinib, it might have minor relevance under clinical conditions. We recently demonstrated that the multidrug and toxin extrusion protein 1 (MATE1) accepts Imatinib as a substrate.
Aims
In this study, we focused on transporters, which are relevant for Imatinib uptake and investigated their expression pattern in PBMCs and if they contribute to Imatinib uptake and expression in samples from CML patients or CML cell lines.
Methods
We used PBMC from 6 healthy volunteers and transporter expression profile was analyzed by qPCR and intracellular Imatinib accumulation was quantified by HPLC-UV using stably transfected HEK cells. To assess Imatinib dependent biologic effects on MATE1 expression, activity of bcr-Abl1 protein was detected by Western blot analysis using anti-phospho ABL and GAPDH antibody. To address the clinical significance of MATE1 on the Imatinib therapy in CML, we evaluated the clonal growth of the immortalized CML cell line K562 cells stably transduced with shRNA against MATE1 in methylcellulose medium supplemented with Imatinib.
Results
The results showed that Imatinib uptake was significantly increased in OCT1, OCT2- and MATE1 expressing HEK-cells. We found that the transport via MATE1 is clinically highly relevant as represented by a remarkably high quotient for therapy regimes. This is supported by qPCR expression of MATE1 in 31 patients with Bcr-Abl1 major transcript (p210) positive CML.The mRNA expression of potential Imatinib transporters in PBMC of healthy volunteers as well as in K562 cells showed that in both cell types OCT1, OCT2 and MATE1 were detected at similar levels comparable to the Imatinib uptake rate into these cells. Inhibitor studies showed that MATE1 plays an important role in Imatinib accumulation. In patients, Imatinib non-responders showed a significantly lower MATE1 expression than Imatinib responders and we found a correlation between MATE1 transporter expression and clinical response to Imatinib treatment, suggesting that MATE1 might enable to predict whether CML patients are likely to respond to Imatinib therapy.
Conclusion
Thus, we identify MATE1 as the main transporter for the Imatinib dependent therapeutic response of CML patients.
Session topic: E-poster
Keyword(s): Chronic myeloid leukemia, Drug sensitivity, Tyrosine kinase inhibitor
Type: Eposter Presentation
Background
Imatinib is highly effective in the treatment of chronic myeloid leukemia (CML). Up to 30% of CML patients treated with Imatinib as a first-line therapy experience treatment failure. The response rate varies within different stages of the disease. Besides other mechanisms of resistance such as mutations in the Bcr-Abl1 fusion gene, the transport of Imatinib into its target cells has been proposed to be crucial for its effectiveness. As an organic cation, Imatinib has to be actively translocated across the cell membrane. Though some studies suggested a critical role of the organic cation transporter 1 (OCT1) in regulating Imatinib efficacy, other studies could not confirm these findings. Although OCT1 is generally capable to transport Imatinib, it might have minor relevance under clinical conditions. We recently demonstrated that the multidrug and toxin extrusion protein 1 (MATE1) accepts Imatinib as a substrate.
Aims
In this study, we focused on transporters, which are relevant for Imatinib uptake and investigated their expression pattern in PBMCs and if they contribute to Imatinib uptake and expression in samples from CML patients or CML cell lines.
Methods
We used PBMC from 6 healthy volunteers and transporter expression profile was analyzed by qPCR and intracellular Imatinib accumulation was quantified by HPLC-UV using stably transfected HEK cells. To assess Imatinib dependent biologic effects on MATE1 expression, activity of bcr-Abl1 protein was detected by Western blot analysis using anti-phospho ABL and GAPDH antibody. To address the clinical significance of MATE1 on the Imatinib therapy in CML, we evaluated the clonal growth of the immortalized CML cell line K562 cells stably transduced with shRNA against MATE1 in methylcellulose medium supplemented with Imatinib.
Results
The results showed that Imatinib uptake was significantly increased in OCT1, OCT2- and MATE1 expressing HEK-cells. We found that the transport via MATE1 is clinically highly relevant as represented by a remarkably high quotient for therapy regimes. This is supported by qPCR expression of MATE1 in 31 patients with Bcr-Abl1 major transcript (p210) positive CML.The mRNA expression of potential Imatinib transporters in PBMC of healthy volunteers as well as in K562 cells showed that in both cell types OCT1, OCT2 and MATE1 were detected at similar levels comparable to the Imatinib uptake rate into these cells. Inhibitor studies showed that MATE1 plays an important role in Imatinib accumulation. In patients, Imatinib non-responders showed a significantly lower MATE1 expression than Imatinib responders and we found a correlation between MATE1 transporter expression and clinical response to Imatinib treatment, suggesting that MATE1 might enable to predict whether CML patients are likely to respond to Imatinib therapy.
Conclusion
Thus, we identify MATE1 as the main transporter for the Imatinib dependent therapeutic response of CML patients.
Session topic: E-poster
Keyword(s): Chronic myeloid leukemia, Drug sensitivity, Tyrosine kinase inhibitor
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