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arXiv · 1912.07927

Deregulation of calcium homeostasis in Bcr-Abl-dependent chronic myeloid leukemia

Hélène Cabanas·Thomas Harnois·Christophe Magaud·Laëtitia Cousin·Bruno Constantin·Nicolas Bourmeyster·Nadine Déliot
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Abstract

Background: Chronic myeloid leukemia (CML) results from hematopoietic stem cell transformation by the bcr-abl chimeric oncogene, encoding a 210 kDa protein with constitutive tyrosine kinase activity. In spite of the efficiency of tyrosine kinase inhibitors (TKI; Imatinib), other strategies are explored to eliminate CML leukemia stem cells, such as calcium pathways. Results: In this work, we showed that Store-Operated Calcium Entry (SOCE) and thrombin induced calcium influx were decreased in Bcr-Abl expressing 32d cells (32d-p210). The 32d-p210 cells showed modified Orai1/STIM1 ratio and reduced TRPC1 expression that could explain SOCE reduction. Decrease in SOCE and thrombin induced calcium entry was associated to reduced Nuclear Factor of Activated T cells (NFAT) nucleus translocation in 32d-p210 cells. We demonstrated that SOCE blockers enhanced cell mobility of 32d-p210 cells and reduced the proliferation rate in both 32d cell lines. TKI treatment slightly reduced the thrombin-induced response, but imatinib restored SOCE to the wild type level. Bcr-Abl is also known to deregulate Protein Kinase C (PKC), which was described to modulate calcium entries. We showed that PKC enhances SOCE and thrombin induced calcium entries in control cells while this effect is lost in Bcr-Abl-expressing cells. Conclusion: The tyrosine kinase activity seems to regulate calcium entries probably not directly but through a global cellular reorganization involving a PKC pathway. Altogether, calcium entries are deregulated in Bcr-Abl-expressing cells and could represent an interesting therapeutic target in combination with TKI.

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Hélène Cabanas, Thomas Harnois, Christophe Magaud, Laëtitia Cousin, Bruno Constantin, Nicolas Bourmeyster, Nadine Déliot. 2019-12-17. Deregulation of calcium homeostasis in Bcr-Abl-dependent chronic myeloid leukemia. https://arxiv.org/abs/1912.07927

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