Green tea polyphenol EGCG induces lipid-raft clustering and apoptotic cell death by activating protein kinase Cδ and acid sphingomyelinase through a 67 kDa laminin receptor in multiple myeloma cells

2012 ◽  
Vol 443 (2) ◽  
pp. 525-534 ◽  
Author(s):  
Shuntaro Tsukamoto ◽  
Keisuke Hirotsu ◽  
Motofumi Kumazoe ◽  
Yoko Goto ◽  
Kaori Sugihara ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Protein Kinase ◽  
Lipid Raft ◽  
Apoptotic Cell ◽  
Acid Sphingomyelinase ◽  
Laminin Receptor ◽  
Myeloma Cells ◽  
Raft Clustering ◽  
Protein Kinase Cδ

EGCG [(−)-epigallocatechin-3-O-gallate], the major polyphenol of green tea, has cancer chemopreventive and chemotherapeutic activities. EGCG selectively inhibits cell growth and induces apoptosis in cancer cells without adversely affecting normal cells; however, the underlying molecular mechanism in vivo is unclear. In the present study, we show that EGCG-induced apoptotic activity is attributed to a lipid-raft clustering mediated through 67LR (67 kDa laminin receptor) that is significantly elevated in MM (multiple myeloma) cells relative to normal peripheral blood mononuclear cells, and that aSMase (acid sphingomyelinase) is critical for the lipid-raft clustering and the apoptotic cell death induced by EGCG. We also found that EGCG induces aSMase translocation to the plasma membrane and PKCδ (protein kinase Cδ) phosphorylation at Ser664, which was necessary for aSMase/ceramide signalling via 67LR. Additionally, orally administered EGCG activated PKCδ and aSMase in a murine MM xenograft model. These results elucidate a novel cell-death pathway triggered by EGCG for the specific killing of MM cells.

A Green Tea Polyphenol, Epigallocatechin-3-Gallate, Induces Selective Apoptosis in Multiple Myeloma Cells: Mechanism of Action and Therapeutic Potential.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1590-1590
Author(s):  
Masood A. Shammas ◽  
Ramesh B. Batchu ◽  
Hemanta Koley ◽  
Robert C. Bertheau ◽  
Paola Neri ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Protein Kinase ◽  
Green Tea ◽  
Mechanism Of Action ◽  
Myeloma Cell ◽  
Laminin Receptor ◽  
Normal Cells ◽  
Myeloma Cells ◽  
Anti Cancer

Abstract Epigallocatechin-3-gallate (EGCG), a polyphenol extracted from green tea, induces dose and time dependent cell death in both IL-6-dependent and independent multiple myeloma cell lines and primary patient cells, with minimal or no effect on the growth of normal cells. The cell death is apoptotic as determined by annexin V staining and is not inhibited by IL-6. Evaluation of molecular mechanism of action by gene expression profiling indicated that EGCG had a profound effect on transcription of major regulatory genes involved in distinct pathways controlling cell growth arrest and apoptosis: Exposure of myeloma cells to EGCG induced the expression of: 1) Fas ligand, Fas, and caspase 4, the initiators and mediators of death receptor dependent apoptosis; 2) death-associated protein kinase 2, a multifunctional pro-apoptotic protein kinase; 3) P53-like proteins, p73, p63; 4) CARD10 and CARD14, positive regulators of apoptosis and NF-kappaB activation; and 5) Cyclin-dependent kinase inhibitors, p16 and p18. In a subset of these selected genes, the expression data is also confirmed with western blot analyses. We have also demonstrated that the transcript and protein levels of a metastasis associated laminin receptor 1 are significantly elevated in myeloma cell lines and patient samples compared to normal cells. RNAi mediated inhibition of laminin receptor 1, abrogated EGCG-induced apoptosis in myeloma cells thus indicating that the profound anti-cancer effect of this compound is probably mediated through this receptor. The selective expression of this receptor explains the selective activity of EGCG in multiple myeloma cells without adversely affecting normal cells. Taken together these data confirm significant and selective anti-cancer activity of EGCG, a natural product, in MM and provides the basis for its clinical evaluation.

Sphingolipids as a novel target for the treatment of multiple myeloma.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e19534-e19534
Author(s):  
Yubin Kang ◽  
Jagadish Kummetha Venketa
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Line ◽  
Cell Lines ◽  
Apoptotic Cell ◽  
Myeloma Cell ◽  
Sphingolipid Metabolism ◽  
Myeloma Cell Line ◽  
Myeloma Cells ◽  
Novel Target

e19534 Background: Multiple myeloma (MM) is the second most common hematological malignancy in the United States and accounts for ~10,600 deaths annually. MM remains an incurable disease and almost all patients will eventually relapse and become refractory to currently available therapeutic agents. There is an unmet need for better understanding the disease’s molecular pathways and for identifying novel therapeutic targets. Sphingolipid metabolism is being increasingly recognized as a key pathway in tumor cell proliferation and in tumor sensitivity to anticancer drugs. We hypothesize that altered sphingolipid metabolism plays an important role in the pathogenesis of MM, thus providing a novel target in the treatment of MM. Methods: We first assayed sphingolipid metabolism including sphingolipid metabolites and sphingolipid metabolizing genes in myeloma cell lines, in freshly isolated human primary CD138+myeloma cells, and in publically available dataset. We then tested the efficacy of the selective SK2 inhibitor (ABC294640) and the SK2 shRNA in killing myeloma cells in vitro. Results: 1) Compared to immortalized B cells, the levels of pro-apoptotic ceramides were decreased whereas the proliferative sphingosine 1-phosphate (S1P) was increased in myeloma cell lines. 2) The expression of several key sphingolipid-metabolizing genes including sphingosine kinase (SK) 1 and 2 was altered in freshly isolated human primary bone marrow myeloma cells and in publically available microarray dataset. 3) The selective SK2 inhibitor (ABC294640) induces apoptotic cell death and inhibits myeloma cell growth with an IC50of ~20 μM in 9 myeloma cell lines. 4) Interestingly, OPM-1 myeloma cell line was extremely sensitive to ABC294640 with an IC50of <5 µM whereas U266 myeloma cell line was resistant to ABC294640. SK2 shRNA induced apoptotic cell death in OPM-1, but not in U266 cells. We are currently investigating the molecular mechanisms underlying the resistance of U266 myeloma cells to ABC294640. Conclusions: Our data demonstrated that sphingolipid metabolism provides an attractive target in the treatment of refractory/relapased multiple myeloma.

Novel Therapeutic Approach to Overcome Both Bortezomib- and Lenalidomide-Resistant Multiple Myeloma By Targeting TOPK/PBK

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1763-1763
Author(s):  
Takayuki Tabayashi ◽  
Yasuyuki Takahashi ◽  
Yuta Kimura ◽  
Tatsuki Tomikawa ◽  
Tomoe Nemoto-Anan ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Protein Kinase ◽  
Cell Growth ◽  
Research Funding ◽  
Apoptotic Cell ◽  
Mapk Signaling ◽  
Apoptotic Cell Death ◽  
Dependent Manner ◽  
Dose Dependent

Abstract Multiple myeloma (MM) is a neoplasm of plasma cells that often remains fatal despite the use of high-dose chemotherapy with hematopoietic stem cell transplantation. In the clinical setting, the introduction of novel agents, such as proteasome inhibitors and immunomodulatory drugs, has improved the clinical outcomes of both patients with newly diagnosed MM and patients with advanced MM. However, most patients eventually relapse and develop drug resistance. T-LAK cell-originated protein kinase (TOPK), also known as PDZ-binding kinase (PBK), is a mitogen-activated protein kinase kinase (MAPKK)-like serine/threonine kinase that plays a critical role in many cellular functions, such as cell proliferation, apoptotic cell death, and inflammation, in normal tissues. Because the expression of TOPK is up-regulated during mitosis and is activated by the Cdk1/cyclin B1 complex, TOPK is thought to have a role in cytokinesis. While the expression of TOPK is very low in most normal human tissues except for testis and placenta, it is overexpressed in various malignant neoplasms, indicating its crucial role in tumorigenesis. Phosphorylation of TOPK leads to the activation of the MAPK signaling pathway including p38 and Ras extracellular signal-regulated kinase (ERK). Moreover, TOPK interacts with p53 tumor suppressor protein and inhibits its function. Ribosomal protein S6 kinase (RSK2) is a downstream target of the ERK/MAPK signaling cascade and it has a pivotal role in cell survival and proliferation. Recent studies suggest that RSK2 inhibition induces apoptotic cell death and sensitizes MM cells to lenalidomide. Suppression of p53 function is also involved in MM progression. Taken together, these data suggest that TOPK might be an attractive target for new therapeutic agents against this incurable hematological malignancy. HI-TOPK-032, which is a potent and specific inhibitor of TOPK, occupies the ATP-binding site of TOPK and thereby suppresses TOPK kinase activity. In the present study, we investigated the role of TOPK/PBK in MM as a potential therapeutic target by using HI-TOPK-032. MTSand trypan blue dye exclusion assays showed that HI-TOPK-032 inhibited the proliferation of various MM cell lines, including U266, RPMI8226, MM1.S, OPM-2, and KMS-11, in a dose- (0 to 10 mM) and time- (0 to 72 h) dependent manner. To examine the mechanisms behind the growth inhibition effect induced by HI-TOPK-032, assays for apoptotic cell death were performed; these assays demonstrated that HI-TOPK-032 induced both early and late apoptosis in MM cells. To investigate the molecular mechanisms of HI-TOPK-032-induced cell death in MM cells, the expression of various cell death-associated proteins and down-stream molecules of TOPK was examined. Western blotting analysis showed that HI-TOPK-032 arrested cell growth and induced apoptotic cell death in MM cells in a dose-dependent manner by reducing t he phosphorylation of ERK and RSK2, thereby reducing the expression of the target molecules of RSK2, i.e., MCL1 and c-Myc. Moreover, HI-TOPK-032 induced p53 expression in a dose-dependent manner. We next examined the effects of HI-TOPK-032 on bortezomib (BTZ)-resistant MM cells, which represent an urgent issue in clinics and for which a therapeutic solution is important. Interestingly, HI-TOPK-032 inhibited the proliferation of both BTZ-sensitive wild-type KMS cells and BTZ-resistant KMS cells, suggesting that BTZ resistance can be overcome by targeting TOPK. Because our results showed that HI-TOPK-032 reduced the phosphorylation of RSK2, and previous studies have suggested that RSK2 inhibition sensitized MM cells to lenalidomide, we next studied the effects of HI-TOPK-032 in combination with lenalidomide on MM cell growth. HI-TOPK-032 and lenalidomide synergisticallyinduced growth arrest in not only lenalidomide-sensitive MM cells, but also in lenalidomide-resistant cells. To determine whether HI-TOPK-032 can re-sensitize BTZ-resistant cells to the anti-MM activity of BTZ, the effects of the combination of HI-TOPK-032 and BTZ were tested using an MTS assay. Interestingly, HI-TOPK-032 was able to re-sensitize BTZ-resistant MM cells to BTZ. These results indicate that the inhibition of TOPK may serve as an attractive therapeutic option for both patients with BTZ- or lenalidomide-resistant MM. In conclusion, these data suggest that TOPK/PBK can be a promising molecular target for the treatment of MM. Disclosures Kizaki: Nippon Shinyaku Co., Ltd.: Research Funding; Ono Phranacutical Co., Ltd.: Consultancy; Kyowa Hakko Kirin Co., Ltd.: Research Funding; Chugai Phrarmaceutical Co., Ltd.: Research Funding.

scholarly journals Protein kinase Cδ regulates vaccinia-related kinase 1 in DNA damage–induced apoptosis

2011 ◽  
Vol 22 (8) ◽  
pp. 1398-1408 ◽  
Author(s):  
Choon-Ho Park ◽  
Bo-Hwa Choi ◽  
Min-Woo Jeong ◽  
Sangjune Kim ◽  
Wanil Kim ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Protein Kinase ◽  
Cell Viability ◽  
Apoptotic Cell ◽  
Critical Role ◽  
Regulatory Region ◽  
Dependent Manner ◽  
Protein Kinase Cδ

Vaccinia-related kinase 1 (VRK1) is a novel serine/threonine kinase that plays an important role in cell proliferation. However, little is known about the upstream regulators of VRK1 activity. Here we provide evidence for a role of protein kinase Cδ (PKCδ) in the regulation of murine VRK1. We show that PKCδ interacts with VRK1, phosphorylates the Ser-355 residue in the putative regulatory region, and negatively regulates its kinase activity in vitro. Intriguingly, PKCδ-induced cell death was facilitated by phosphorylation of VRK1 when cells were exposed to a DNA-damaging agent. In addition, p53 played a critical role in the regulation of DNA damage–induced cell death accompanied by PKCδ-mediated modulation of VRK1. In p53-deficient cells, PKCδ-mediated phosphorylation of VRK1 had no effect on cell viability. However, cells overexpressing p53 exhibited significant reduction of cell viability when cotransfected with both VRK1 and PKCδ. Taken together, these results indicate that PKCδ regulates phosphorylation and down-regulation of VRK1, thereby contributing to cell cycle arrest and apoptotic cell death in a p53-dependent manner.

scholarly journals Phosphocatalytic Kinome Activity Profiling of Apoptotic and Ferroptotic Agents in Multiple Myeloma Cells

2021 ◽  
Vol 22 (23) ◽  
pp. 12731
Author(s):  
Emilie Logie ◽  
Claudina Perez Novo ◽  
Amber Driesen ◽  
Pieter Van Vlierberghe ◽  
Wim Vanden Berghe
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Tyrosine Kinases ◽  
Kinase Inhibitors ◽  
Apoptotic Cell ◽  
Protein Kinase Inhibitors ◽  
Withaferin A ◽  
Myeloma Cells ◽  
Activity Profiling ◽  
Anti Cancer

Through phosphorylation of their substrate proteins, protein kinases are crucial for transducing cellular signals and orchestrating biological processes, including cell death and survival. Recent studies have revealed that kinases are involved in ferroptosis, an iron-dependent mode of cell death associated with toxic lipid peroxidation. Given that ferroptosis is being explored as an alternative strategy to eliminate apoptosis-resistant tumor cells, further characterization of ferroptosis-dependent kinase changes might aid in identifying novel druggable targets for protein kinase inhibitors in the context of cancer treatment. To this end, we performed a phosphopeptidome based kinase activity profiling of glucocorticoid-resistant multiple myeloma cells treated with either the apoptosis inducer staurosporine (STS) or ferroptosis inducer RSL3 and compared their kinome activity signatures. Our data demonstrate that both cell death mechanisms inhibit the activity of kinases classified into the CMGC and AGC families, with STS showing a broader spectrum of serine/threonine kinase inhibition. In contrast, RSL3 targets a significant number of tyrosine kinases, including key players of the B-cell receptor signaling pathway. Remarkably, additional kinase profiling of the anti-cancer agent withaferin A revealed considerable overlap with ferroptosis and apoptosis kinome activity, explaining why withaferin A can induce mixed ferroptotic and apoptotic cell death features. Altogether, we show that apoptotic and ferroptotic cell death induce different kinase signaling changes and that kinome profiling might become a valid approach to identify cell death chemosensitization modalities of novel anti-cancer agents.

scholarly journals Specific killing of multiple myeloma cells by (-)-epigallocatechin-3-gallate extracted from green tea: biologic activity and therapeutic implications

Blood ◽  
2006 ◽  
Vol 108 (8) ◽  
pp. 2804-2810 ◽  
Author(s):  
Masood A. Shammas ◽  
Paola Neri ◽  
Hemanta Koley ◽  
Ramesh B. Batchu ◽  
Robert C. Bertheau ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Green Tea ◽  
Fas Ligand ◽  
Mononuclear Cells ◽  
Apoptotic Cell ◽  
Growth Arrest ◽  
Laminin Receptor ◽  
Peripheral Blood Mononuclear ◽  
Myeloma Cells

AbstractEpigallocatechin-3-gallate (EGCG), a polyphenol extracted from green tea, is an antioxidant with chemopreventive and chemotherapeutic actions. Based on its ability to modulate growth factor-mediated cell proliferation, we evaluated its efficacy in multiple myeloma (MM). EGCG induced both dose- and time-dependent growth arrest and subsequent apoptotic cell death in MM cell lines including IL-6-dependent cells and primary patient cells, without significant effect on the growth of peripheral blood mononuclear cells (PBMCs) and normal fibroblasts. Treatment with EGCG also led to significant apoptosis in human myeloma cells grown as tumors in SCID mice. EGCG interacts with the 67-kDa laminin receptor 1 (LR1), which is significantly elevated in myeloma cell lines and patient samples relative to normal PBMCs. RNAi-mediated inhibition of LR1 resulted in abrogation of EGCG-induced apoptosis in myeloma cells, indicating that LR1 plays an important role in mediating EGCG activity in MM while sparing PBMCs. Evaluation of changes in gene expression profile indicates that EGCG treatment activates distinct pathways of growth arrest and apoptosis in MM cells by inducing the expression of death-associated protein kinase 2, the initiators and mediators of death receptor-dependent apoptosis (Fas ligand, Fas, and caspase 4), p53-like proteins (p73, p63), positive regulators of apoptosis and NF-κB activation (CARD10, CARD14), and cyclin-dependent kinase inhibitors (p16 and p18). Expression of related genes at the protein level were also confirmed by Western blot analysis. These data demonstrate potent and specific antimyeloma activity of EGCG and provide the rationale for its clinical evaluation.

Apoptin Induced Tumour Specific Killing Via Protein Kinase C Isoforms: A Potential Therapeutic Strategy In Plasma Cell Dyscrasias

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 5039-5039
Author(s):  
Jie Jiang ◽  
Daryl Cole ◽  
Nigel Westwood ◽  
Lee Macpherson ◽  
Farzin Farzaneh ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Line ◽  
Phosphorylation Sites ◽  
Normal Cells ◽  
Myeloma Cells ◽  
Kinase C

Abstract Abstract 5039 There is mounting evidence that malignant cells have an intrinsic ability to prevent apoptosis. In the present study we provide evidence that the ectopic expression of Apoptin can restore the failing apoptosis program in myeloma cells via protein kinase C b (PKCb) and overcome intrinsic or acquired resistance to cell death. Apoptin (VP3), a chicken anemia virus (CAV)-derived protein has been shown to possess tumor specific cytotoxicity; its expression induces apoptosis in human tumor and transformed cells but there is little or no cytotoxic effect in normal human cells or cell lines derived from different tissues including peripheral blood mononuclear cells, fibroblast and epithelial cells. Several studies have shown that the tumor specific killing of Apoptin correlates with its phosphorylation and its subcellular localization. In cancer cells, Apoptin is localized in the nucleus and is phosphorylated on threonine108 by an as yet unknown kinase, whereas in normal cells Apoptin is detected in the cytoplasm and is essentially unphosphorylated. We developed a lentiviral vector encoding a GFP-Apoptin fusion gene (LV-GFP-AP), which delivers the Apoptin gene efficiently to haematopoietic cells. Apoptin significantly and selectively killed a number of leukemia cell lines including K562, HL60, U937, KG1 and NB4. In particular, the dexamethasone resistant multiple myeloma cell line MM1.R and the dexamethasone sensitive cell line MM1.S were efficiently killed by Apoptin. In contrast normal CD34+ cells were not killed and maintained their differentiation potential in multilineage colony formation assays. In addition, we showed that the dexamethasone resistant MM1.R cells were considerably more susceptible to Apoptin induced cell death than the parental matched MM1.S cells. This correlated with increased phosphorylation and activation of the Apoptin protein in MM1.R cells. Expression profiling of MM1.R and MM1.S cells identified a number of differentially expressed kinases. PKCb was over-expressed 9 fold in MM1.R cells and we showed, by immunoprecipitation and in vivo kinase studies, that this kinase was responsible for Apoptin phosphorylation. Analysis of the Apoptin amino acid sequence for potential phosphorylation sites indicated seven putative phosphorylation sites corresponding to the PKC kinase consensus motifs (S/TXK/R or S/TXXK/R). These sites included Thr-108, which has been previously shown to be phosphorylated in tumor cells, but not in normal cells. In vitro studies showed that recombinant Apoptin protein was phosphorylated by recombinant GST-PKCb protein at the Thr-108 site. Addition of a PKCb specific inhibitor resulted in diminished Apoptin phosphorylation whilst an unrelated inhibitor had no such effect. Furthermore, shRNA knockdown or drug mediated inhibition of PKCb in vivo significantly reduced Apoptin phosphorylation. Finally, we found that Apoptin mediated cell death proceeded via the up-regulation of PKCb, activation of caspase-9/3, cleavage of the PKCd catalytic domain and down-regulation of MERTK and AKT protein kinases. Collectively these results demonstrate a novel pathway for Apoptin activation involving PKCb and PKCd. Our results show that Apoptin is able to effectively eliminate multiple myeloma cells which have become resistant to dexamethasone. In addition, this study has led to the identification of tumor specific cellular targets such as PKCb, whose modulation by shRNAs and small molecule drugs can induce strong anti-myeloma effects. Importantly, the evidence from our data suggests that protein kinase C inhibitors may have an important therapeutic role in plasma cell neoplasia. Disclosures: No relevant conflicts of interest to declare.

scholarly journals 3-Phosphoinositide-Dependent Protein Kinase 1 (PDPK1) Is a Pivotal Cell Signaling Mediator in Multiple Myeloma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4728-4728
Author(s):  
Yoshiaki Chinen ◽  
Junya Kuroda ◽  
Yuji Shimura ◽  
Hisao Nagoshi ◽  
Miki Kiyota ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Treatment Outcome ◽  
Protein Kinase ◽  
Cell Lines ◽  
Therapeutic Target ◽  
Disease Stage ◽  
Dependent Protein Kinase ◽  
Myeloma Cells ◽  
Dependent Protein

Abstract Multiple myeloma (MM) is a highly molecularly heterogeneous hematologic malignancy and remains mostly incurable despite recent improvement of treatment outcome by novel agents. Therefore, the identification of novel and universal targetable therapeutic molecules is a core component for the therapeutic development. Herein, we identified that 3-phosphoinositide-dependent protein kinase 1 (PDPK1), a member of serine threonine kinase, is a rationalistic candidate of a novel therapeutic target against MM. PDPK1 is universally phosphorylated in all eleven MM-derived cell lines examined regardless of type of cytogenetic/genetic abnormalities or the activation/mutation state of FGFR3, RAS, ERK and AKT. PDPK1 promotes the cell proliferation of myeloma cells by activating RSK2Ser227 at N-terminal kinase domain which is a pivotal regulator of molecules that are essential for myelomagenesis, such as c-MYC, IRF4, or Cyclin Ds (Shimura Y, Mol Cancer Ther 2011), and AKTThr308. In contrast, PDPK1 inhibition by a selective inhibitor, BX-912, caused G2/M arrest, which was accompanied by the inactivation of PLK1, and resulted in cell death via induction of apoptosis which was accompanied by the activation of pro-apoptotic BH3-only proteins, BIM and BAD, in myeloma-derived cell lines. These molecular and cytological effects of PDPK1 inhibition in myeloma cells were also validated by gene knockdown by means of RNA interference using two different siRNAs specific for PDPK1. In addition, the cytotoxic effect of BX-912 was not hampered in two cell lines acquiring resistance to bortezomib (BTZ) (Ri M, Leukemia 2010), and PDPK1 inhibition by BX-912 showed additive to synergistic in vitro cytotoxic effects on myeloma cells with melphalan, etoposide, bortezomib or BAY11-7085, an inhibitor for NF-κB. BX-912 also induced cell death in eleven patient-derived primary myeloma cells those were positively isolated by CD138-labelling from bone marrow aspirates, while normal peripheral lymphocytes were significantly less sensitive to PDPK1 inhibitor compared with MM cells. In the clinical setting, PDPK1 was active in myeloma cells of 57 of 65 (87.7%) symptomatic MM patients at diagnosis. While patients backgrounds, such as age, gender, and the type of M-protein, were not significantly different between PDPK1-negative (PDPK1(-)) and PDPK1-positive (PDPK1(+)) patients, patients with the disease stage III according to International Staging System were significantly more frequent in the PDPK1(+) cohort compared with PDPK1(-) cohort. The PDPK1(-) patients tended to exhibit longer overall survival (OS) than the patients with PDPK1(+) (median OS: 2925 days vs. 2155 days, p=0.069) with a median follow-up period of 1310 days (range: 228–3317 days). Of particular, the 8-year OS of PDPK1(-) patients was statistically significantly more favorable than those of PDPK1(+) patients (83% vs. 17%, p=0.041). In addition, when we analyzed the impact of PDPK1 activity on the treatment outcome of patients treated by BTZ and dexamethasone therapy (BD), our results revealed that progression free survival (PFS) of patients with PDPK1(-) was a significantly longer than those of patients with PDPK1(+) (median PFS: PDPK1(-) vs. PDPK1(+), not reached vs. 167 days, p=0.049). The PFS of PDPK1(-) patients treated by high-dose therapy/autologous stem cell transplantation (HDT/ASCT) tended to be longer than those of PDPK1(+) (median PFS: PDPK1(-) vs. PDPK1(+), 972 days vs. 567 days, p=0.125). In conclusion, our study provides the rationale for PDPK1 as a possible universal molecular target for MM with various molecular/cytogenetic features. Especially, PDPK1 is a potential therapeutic target for not only newly diagnosed patients but also patients who are resistant or refractory to currently available anti-myeloma therapies. This study was conducted in accordance with the Declaration of Helsinki and with the approval of the Institutional Review Board. Patient-derived samples were obtained with informed consent. Disclosures No relevant conflicts of interest to declare.

scholarly journals Transcriptional Regulation of Pro-apoptotic Protein Kinase Cδ

2011 ◽  
Vol 286 (22) ◽  
pp. 19840-19859 ◽  
Author(s):  
Huajun Jin ◽  
Arthi Kanthasamy ◽  
Vellareddy Anantharam ◽  
Ajay Rana ◽  
Anumantha G. Kanthasamy
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Promoter Activity ◽  
Molecular Mechanisms ◽  
Apoptotic Cell ◽  
Neuronal Cells ◽  
Regulatory Region ◽  
Positive Contribution ◽  
Creb Binding Protein ◽  
Protein Kinase Cδ

We previously demonstrated that protein kinase Cδ (PKCδ; PKC delta) is an oxidative stress-sensitive kinase that plays a causal role in apoptotic cell death in neuronal cells. Although PKCδ activation has been extensively studied, relatively little is known about the molecular mechanisms controlling PKCδ expression. To characterize the regulation of PKCδ expression, we cloned an ∼2-kbp 5′-promoter segment of the mouse Prkcd gene. Deletion analysis indicated that the noncoding exon 1 region contained multiple Sp sites, including four GC boxes and one CACCC box, which directed the highest levels of transcription in neuronal cells. In addition, an upstream regulatory region containing adjacent repressive and anti-repressive elements with opposing regulatory activities was identified within the region −712 to −560. Detailed mutagenesis studies revealed that each Sp site made a positive contribution to PKCδ promoter expression. Overexpression of Sp family proteins markedly stimulated PKCδ promoter activity without any synergistic transactivating effect. Furthermore, experiments in Sp-deficient SL2 cells indicated long isoform Sp3 as the essential activator of PKCδ transcription. Importantly, both PKCδ promoter activity and endogenous PKCδ expression in NIE115 cells and primary striatal cultures were inhibited by mithramycin A. The results from chromatin immunoprecipitation and gel shift assays further confirmed the functional binding of Sp proteins to the PKCδ promoter. Additionally, we demonstrated that overexpression of p300 or CREB-binding protein increases the PKCδ promoter activity. This stimulatory effect requires intact Sp-binding sites and is independent of p300 histone acetyltransferase activity. Finally, modulation of Sp transcriptional activity or protein level profoundly altered the cell death induced by oxidative insult, demonstrating the functional significance of Sp-dependent PKCδ gene expression. Collectively, our findings may have implications for development of new translational strategies against oxidative damage.

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