Induction of Apoptosis through B-cell Receptor Cross-linking Occurs via de Novo Generated C16-Ceramide and Involves Mitochondria

Kroesen, Bart-Jan; Pettus, Benjamin J.; Luberto, Chiara; Busman, Mark; Sietsma, Hannie; Leij, de Louis; Hannun, Y. A.

doi:10.1074/jbc.m009517200

Cited by 151 publications

(133 citation statements)

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“…Previous studies have shown that ceramide has a direct proapoptotic effect on the mitochondrial cascade. 7,8,25 Overall, these findings led us to investigate the involvement of BEX2 in the mitochondrial apoptosis pathway.…”

Section: Discussionmentioning

confidence: 99%

“…[7][8][9][10]25 To investigate this we first carried out a mitochondrial permeability transition (MPT)-based apoptosis assay, which detects changes in…”

Section: Bex2 Protects the Breast Cancer Cells Against Mitochondrial mentioning

confidence: 99%

“…6 Previous studies have shown that ceramide-induced apoptosis involves a direct action on mitochondria. [7][8][9][10] This effect is thought to be regulated by the Bcl-2 family of proteins. [11][12][13] Furthermore, there is a known interaction between the ceramide and NF-jB pathways.…”

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confidence: 99%

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BEX2 regulates mitochondrial apoptosis and G1 cell cycle in breast cancer

Naderi¹,

Liu²,

Bennett³

2010

Intl Journal of Cancer

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We have recently demonstrated that BEX2 is differentially expressed in primary breast tumors and BEX2 expression is required for the Nerve Growth factor inhibition of ceramide-induced apoptosis in breast cancer. In this study we investigate the functional role of BEX2 in the survival and growth of breast cancer cells. We demonstrate that BEX2 downregulation induces mitochondrial apoptosis and sensitizes breast cancer cells to the pro-apoptotic effects of ceramide, doxorubicin and staurosporine. In addition, BEX2 overexpression protects the breast cancer cells against mitochondrial apoptosis. We show that this effect of BEX2 is mediated through the modulation of Bcl-2 protein family, which involves the positive regulation of anti-apoptotic member Bcl-2 and the negative regulation of pro-apoptotic members BAD, BAK1 and PUMA. Moreover, our data suggests that BEX2 expression is required for the normal cell cycle progression during G1 in breast cancer cells through the regulation of cyclin D1 and p21. To further support the significance of BEX2 in the pathogenesis of breast cancer we demonstrate that BEX2 overexpression is associated with a higher activation of the Bcl-2/NF-jB pathway in primary breast tumors. Furthermore, we show that BEX2 downregulation results in a higher expression and activity of protein phosphatase 2A. The modulation of protein phosphatase 2A, which is also known to mediate the cellular response to ceramide, provides a possible mechanism to explain the BEX2-mediated cellular effects. This study demonstrates that BEX2 has a significant role in the regulation of mitochondrial apoptosis and G1 cell cycle in breast cancer.

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Section: Discussionmentioning

confidence: 99%

“…[7][8][9][10]25 To investigate this we first carried out a mitochondrial permeability transition (MPT)-based apoptosis assay, which detects changes in…”

Section: Bex2 Protects the Breast Cancer Cells Against Mitochondrial mentioning

confidence: 99%

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BEX2 regulates mitochondrial apoptosis and G1 cell cycle in breast cancer

Naderi¹,

Liu²,

Bennett³

2010

Intl Journal of Cancer

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“…For example, previous studies have shown that de novo generated ceramide in response to stimulation of the BcR receptor in B cells results in selective accumulation of C 16 -ceramide (23), and this was implicated in the apoptotic response of those cells (24). On the other hand, activation of neutral SMase2 was shown to selectively induce the formation of C 24 -ceramide and C 24:1 -ceramide, and evidence was provided for a role for this pathway in cell cycle regulation (25) and in interleukin-6 formation (26).…”

Section: Discussionmentioning

confidence: 99%

Selective Inhibition of Juxtanuclear Translocation of Protein Kinase C βII by a Negative Feedback Mechanism Involving Ceramide Formed from the Salvage Pathway

Becker

Kitatani

Idkowiak‐Baldys

et al. 2005

Journal of Biological Chemistry

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In a previous study, we showed that protein kinase C ␤II (PKC ␤II) translocated to a novel juxtanuclear compartment as observed in several cell types (Becker, K. P., and Hannun, Y. A. (2003) J. Biol. Chem. 278, 52747-52754). In this study, we noted the absence of this translocation in MCF-7 breast cancer cells, and we examined the mechanisms underlying this selectivity of response. We show that sustained stimulation of PKC ␤II with 4␤-phorbol 12-myristate 13-acetate (PMA) resulted in accumulation of ceramide in MCF-7 cells but not in those cells that showed juxtanuclear translocation of PKC ␤II. Addition of exogenous ceramides or formation of endogenous ceramide by the action of bacterial sphingomyelinase prevented PMA-induced translocation of PKC ␤II in HEK 293 cells. On the other hand, inhibition of ceramide accumulation with fumonisin B1 restored the ability of PMA to induce translocation of PKC ␤II in MCF-7 cells. Taken together, the results showed that endogenous ceramide is both necessary and sufficient for preventing juxtanuclear translocation of PKC ␤II in response to PMA. Investigation of the mechanisms of ceramide generation in response to PMA revealed that PMA activated the salvage pathway of ceramide formation and not the de novo pathway. This conclusion was based on the following: 1) the ability of fumonisin B1 but not myriocin to inhibit ceramide formation, 2) the ability of PMA to induce increases in palmitate-labeled ceramide only under chase labeling but not acute pulse labeling, 3) the induction of the levels of sphingosine but not dihydrosphingosine in response to PMA, and 4) induction of sphingomyelin hydrolysis in response to PMA. Together, these results define a novel pathway of regulated formation of ceramide, the salvage pathway, and they define a role for this pathway in regulating juxtanuclear translocation of PKC ␤II.The isoenzymes of protein kinase C (PKC), 1 designated as the classical PKCs, comprise a subfamily of closely related isoenzymes that share similar structural features and mechanisms of action and regulation. This group consists of PKC ␣, PKC ␤I, PKC ␤II, and PKC ␥ that share highly homologous regulatory domains and are activated by diacylglycerol (DAG) and calcium. Thus, they serve as signal transducers for the action of extracellular agonists that activate phospholipases C, which results in the generation of DAG and calcium (2, 3).Activation of PKC requires the translocation of PKC to the plasma membrane in response to acutely generated DAG (3, 4). This translocation also places PKC in proximity to specific membrane substrates. Thus, the dynamic interaction of PKC with membranes has emerged as a key mechanism in regulating its function.Previous studies from our laboratory (1), supported by the recent results from Hu and Exton (5), have demonstrated a novel translocation of PKC ␣ and ␤II to a juxtanuclear region. This novel translocation is seen with prolonged stimulation of these two isoenzymes of PKC by PMA (for at least 30 min) and follows the initial translocation of ...

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“…8,9) The hydrolysis of SM by SMase appears to be a major route for the generation of Cer in response to stimuli such as cytokines, antibodies, steroids, and heat shock, 3,10,11) although de novo synthesis of Cer is also increased by stimuli. 12) Cer can be further processed to sphingosine by ceramidase (CDase) and then to sphingosine 1-phosphate by sphingosine kinase. The latter product is a well-known ligand for G-protein-coupled receptors S1P 1-5 .…”

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confidence: 99%