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

• Published in: Oncotarget Vol. 9; no. 41; pp. 26309 - 26327
• Main Authors: Cabanas, Hélène, Harnois, Thomas, Magaud, Christophe, Cousin, Laëtitia, Constantin, Bruno, Bourmeyster, Nicolas, Déliot, Nadine
• Format: Journal Article
• Language: English
• Published: United States Impact journals 29.05.2018; Impact Journals LLC
• Subjects: Cancer; Cellular Biology; Life Sciences; Research Paper; Subcellular Processes; STIM1/Orai1/TRPC1; chronic myeloid leukemia; leukemogenesis; calcium homeostasis; store-operated calcium entry
• ISSN: 1949-2553; 1949-2553
• DOI: 10.18632/oncotarget.25241

Chronic myeloid leukemia (CML) results from hematopoietic stem cell transformation by the 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. 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. 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.