TY - JOUR
T1 - Coupling of mitochondria to store-operated Ca2+-signaling sustains constitutive activation of protein kinase B/Akt and augments survival of malignant melanoma cells
AU - Feldman, Ben
AU - Fedida-Metula, Shlomit
AU - Nita, Julia
AU - Sekler, Israel
AU - Fishman, Daniel
N1 - Funding Information:
We express our gratitude to Prof. E. Gorelik for B16BL6 melanoma clones, Prof. Miyawaki for RPmt plasmid and Prof. Demaurex for Fis1 plasmid. We also thank Dr. M. Hershfinkel and Prof. W.F. Silverman (Department of Morphology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel) for critical reading of this manuscript and constructive suggestions. The study was partially supported by Israel Science Foundation grants no. 958/08 and 985/05 to D.F. and I.S., respectively, and by German Israeli Foundation grant no. 917-119.1/2006 to I.S.
PY - 2010/1/1
Y1 - 2010/1/1
N2 - Mitochondria are emerging as a major hub for cellular Ca2+-signaling, though their contribution to Ca2+-driven growth- and survival-promoting events in cancer is poorly understood. Here employing flow cytometry to monitor mitochondrial and cytosolic Ca2+, we assessed trans-mitochondrial Ca2+-transport and store-operated Ca2+-influx (store-operated channels (SOC)) in malignant vs. non-malignant B16BL6 melanoma clones. Remarkably, mitochondrial Ca2+-fluxes measured in whole cells or in isolated mitochondria were accelerated in the malignant clones compared to their non-malignant counterpart clones. This coincided with enhanced SOC-mediated Ca2+-influx and high levels of constitutively active protein kinase B/Akt (PKB). Interruption of trans-mitochondrial Ca2+-transport in the malignant cells with an antagonist of the mitochondrial Na+/Ca2+ exchanger, CGP-37157, abolsihed SOC-mediated Ca2+-influx, inactivated PKB, retarded cell growth and increased vulnerability to apoptosis. Similarly, direct SOC blockade by silencing Stim1 inhibited PKB, indicating that the crosstalk between SOC and mitochondria is essential to preserve PKB in constitutively active state. Finally, the retraction of mitochondria from sub-plasmalemmal micro-domains triggered by Fis1 over-expression inhibited SOC-coupled trans-mitochondrial Ca2+-flux, Ca2+-entry via SOC and PKB activity. Taken together, our data show that in the malignant melanoma cells, the functional and spatial relationship of up-regulated mitochondrial Ca2+-transport to the SOC sustains the robust Ca2+-responses and down-stream signaling critical for apoptosis-resistance and proliferation.
AB - Mitochondria are emerging as a major hub for cellular Ca2+-signaling, though their contribution to Ca2+-driven growth- and survival-promoting events in cancer is poorly understood. Here employing flow cytometry to monitor mitochondrial and cytosolic Ca2+, we assessed trans-mitochondrial Ca2+-transport and store-operated Ca2+-influx (store-operated channels (SOC)) in malignant vs. non-malignant B16BL6 melanoma clones. Remarkably, mitochondrial Ca2+-fluxes measured in whole cells or in isolated mitochondria were accelerated in the malignant clones compared to their non-malignant counterpart clones. This coincided with enhanced SOC-mediated Ca2+-influx and high levels of constitutively active protein kinase B/Akt (PKB). Interruption of trans-mitochondrial Ca2+-transport in the malignant cells with an antagonist of the mitochondrial Na+/Ca2+ exchanger, CGP-37157, abolsihed SOC-mediated Ca2+-influx, inactivated PKB, retarded cell growth and increased vulnerability to apoptosis. Similarly, direct SOC blockade by silencing Stim1 inhibited PKB, indicating that the crosstalk between SOC and mitochondria is essential to preserve PKB in constitutively active state. Finally, the retraction of mitochondria from sub-plasmalemmal micro-domains triggered by Fis1 over-expression inhibited SOC-coupled trans-mitochondrial Ca2+-flux, Ca2+-entry via SOC and PKB activity. Taken together, our data show that in the malignant melanoma cells, the functional and spatial relationship of up-regulated mitochondrial Ca2+-transport to the SOC sustains the robust Ca2+-responses and down-stream signaling critical for apoptosis-resistance and proliferation.
KW - Apoptosis
KW - Calcium
KW - Melanoma
KW - Mitochondrium
KW - PKB
UR - http://www.scopus.com/inward/record.url?scp=77953913632&partnerID=8YFLogxK
U2 - 10.1016/j.ceca.2010.05.002
DO - 10.1016/j.ceca.2010.05.002
M3 - Article
C2 - 20605628
AN - SCOPUS:77953913632
SN - 0143-4160
VL - 47
SP - 525
EP - 537
JO - Cell Calcium
JF - Cell Calcium
IS - 6
ER -