Combination of Proteasomal Inhibitors Lactacystin and MG132 Induced Synergistic Apoptosis in Prostate Cancer Cells

Shirley, Robert B.; Kaddour‐Djebbar, Ismail; Patel, Dimpu M.; Lakshmikanthan, Vijayabaskar; Lewis, Ronald W.; Kumar, M. Vijay

doi:10.1593/neo.05520

Cited by 35 publications

(31 citation statements)

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“…TRAIL is an effective apoptotic agent by itself or in combination with other apoptotic drugs. We have shown synergistic increase in apoptotic response when TRAIL was combined with antiprogestin mifepristone (43) or by inhibiting the function of heat shock protein 90 (27,34), inhibiting the proteasomal activity (34), or treatment with histone deacetylase inhibitor, SAHA (25). Our present results show that treatment with both TRAIL and CGP Figure 3.…”

Section: Discussionmentioning

confidence: 50%

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Therapeutic advantage of combining calcium channel blockers and TRAIL in prostate cancer

Kaddour‐Djebbar¹,

Lakshmikanthan²,

Shirley³

et al. 2006

Molecular Cancer Therapeutics

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Section: Discussionmentioning

confidence: 50%

“…This assay is highly sensitive and is specific to cell death due to apoptosis but does not measure necrotic cells. Apoptosense kit has been used successfully in measuring apoptosis in prostate cancer cells (25,27,34). On completion of the experiments, cells were harvested and total protein was extracted as described below.…”

Section: Introductionmentioning

confidence: 99%

Therapeutic advantage of combining calcium channel blockers and TRAIL in prostate cancer

Kaddour‐Djebbar¹,

Lakshmikanthan²,

Shirley³

et al. 2006

Molecular Cancer Therapeutics

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“…Lactacystin Increases sf-CD Accumulation in AtT-20 CellsIn AtT-20 cells expressing Myc-TMD-CD or PAM-1, sf-CD is barely detectable in the absence of the proteasomal inhibitor MG132, a peptidyl aldehyde that also inhibits calpain 1 (15,29). Because the proteasome seemed to play a key role in sf-CD metabolism, we tested another inhibitor.…”

Section: Sf-cd Production From Myc-tmd-cd Ismentioning

confidence: 99%

“…Because the proteasome seemed to play a key role in sf-CD metabolism, we tested another inhibitor. We chose lactacystin, a ␤-lactone that binds covalently but also inhibits cathepsins A and B (29,30). We first examined AtT-20 cells expressing Myc-TMD-CD and treated them for 5 h with lactacystin or MG132 (Fig.…”

Section: Sf-cd Production From Myc-tmd-cd Ismentioning

confidence: 99%

Secretion Stimulates Intramembrane Proteolysis of a Secretory Granule Membrane Enzyme

Rajagopal

Stone

Mains

et al. 2010

Journal of Biological Chemistry

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Regulated intramembrane proteolysis, a highly conserved process employed by diverse regulatory pathways, can release soluble fragments that directly or indirectly modulate gene expression. In this study we used pharmacological tools to identify peptidylglycine ␣-amidating monooxygenase (PAM), a type I secretory granule membrane protein, as a ␥-secretase substrate. PAM, an essential enzyme, catalyzes the final step in the synthesis of the majority of neuropeptides that control metabolic homeostasis. Mass spectroscopy was most consistent with the presence of multiple closely spaced NH 2 termini, suggesting that cleavage occurred near the middle of the PAM transmembrane domain. The luminal domains of PAM must undergo a series of prohormone convertase or ␣-secretase-mediated cleavages before the remaining transmembrane domain/cytosolic domain fragment can undergo a ␥-secretase-like cleavage. Cleavage by ␥-secretase generates a soluble fragment of the cytosolic domain (sf-CD) that is known to localize to the nucleus. Although PAM sf-CD is unstable in AtT-20 corticotroph tumor cells, it is readily detected in primary rat anterior pituitary cells. PAM isoform expression, which is tissue-specific and developmentally regulated, affects the efficiency with which sf-CD is produced. sf-CD levels are also modulated by the phosphorylation status of the cytosolic domain and by the ability of the cytosolic domain to interact with cytosolic proteins. sf-CD is produced by primary rat anterior pituitary cells in response to secretogogue, suggesting that sf-CD acts as a signaling molecule relaying information about secretion from the secretory granule to the nucleus.Cells utilize diverse signaling mechanisms to coordinate the functions of their subcellular organelles and to integrate their metabolism with that of neighboring cells and distant tissues. Regulated intramembrane proteolysis, which is performed by a small group of intramembrane cleaving proteases (i-CLiPs), 2 initiates many of the signaling cascades involved in these pathways. The i-CLiP family includes metalloproteases (S2P), rhomboid serine proteases, signal peptide peptidase aspartyl proteases, and ␥-secretase aspartyl protease complexes (1, 2). For example, signaling pathways that regulate lipid homeostasis modulate cleavage of SREBP by S2P, releasing its transcription factor domain. The unfolded protein response involves S2P-mediated cleavage of ATF6 and nuclear translocation of its N-terminal transcription factor region (3). Many aspects of development involve cleavage of Notch by ␥-secretase, generating a cytosolic domain fragment that translocates to the nucleus, where it participates in the regulation of gene transcription (4). The ␥-secretase-mediated cleavage of amyloid precursor protein (APP) generates amyloidogenic fragments along with a cytosolic fragment whose role is under investigation (5).Secretory granules in the regulated exocytic pathway play an essential role in maintaining homeostasis. Their soluble content includes chromogranins, prohormone conve...

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“…Apoptosense is highly sensitive and is specific to apoptosis. Apoptosense kit has been utilized successfully in our (14,21,22), and other laboratories (23)(24)(25). Protein extract was added to 96-well plates pre-coated with mouse monoclonal M30 antibody, horseradish peroxidase tracer solution was added to the wells and incubated for 4 h. Color was developed by adding tetramethyl benzidine solution and the optical density was measured at 450 nm on a Spectra MAX340 microplate reader (Molecular Devices Corp., Sunnyvale, CA).…”

Section: Measurement Of Apoptosismentioning

confidence: 99%

Specific mitochondrial calcium overload induces mitochondrial fission in prostate cancer cells

Kumar¹

2010

Int J Oncol

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Abstract. Mitochondria are structurally complex organelles that undergo fragmentation or fission in apoptotic cells. Mitochondrial fission requires the cytoplasmic dynamin-related protein, Drp1, which translocates to the mitochondria during apoptosis and interacts with the mitochondrial protein, Fis1. Finely tuned changes in cellular calcium modulate a variety of intracellular functions; in resting cells, the level of mitochondrial calcium is low, while it is higher during apoptosis. Mitochondria take up Ca 2+ via the Uniporter and extrude it to the cytoplasm through the mitochondrial Na + /Ca 2+ exchanger. Overload of Ca 2+ in the mitochondria leads to their damage, affecting cellular function and survival. The mitochondrial Na + /Ca 2+ exchanger was blocked by benzodiazepine, CGP37157 (CGP) leading to increased mitochondrial calcium and enhancing the apoptotic effects of TRAIL, TNF· related apoptosis inducing ligand. In the present study, we observed that increasing mitochondrial calcium induced mitochondrial fragmentation, which correlated with the presence of Drp1 at the mitochondria in CGP treated cells. Under these conditions, we observed interactions between Drp1 and Fis1. The importance of Drp1 in fragmentation was confirmed by transfection of dominant negative Drp1 construct. However, fragmentation of the mitochondria was not sufficient to induce apoptosis, although it enhanced TRAIL-induced apoptosis. Furthermore, oligomerization of Bak was partially responsible for the increased apoptosis in cells treated with both CGP and TRAIL. Thus, our results show that combination of an apoptogenic agent and an appropriate calcium channel blocker provide therapeutic advantages.

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Combination of Proteasomal Inhibitors Lactacystin and MG132 Induced Synergistic Apoptosis in Prostate Cancer Cells

Cited by 35 publications

References 50 publications

Therapeutic advantage of combining calcium channel blockers and TRAIL in prostate cancer

Therapeutic advantage of combining calcium channel blockers and TRAIL in prostate cancer

Secretion Stimulates Intramembrane Proteolysis of a Secretory Granule Membrane Enzyme

Specific mitochondrial calcium overload induces mitochondrial fission in prostate cancer cells

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