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Premkumar DR, Jane EP, Agostino NR, DiDomenico JD, Pollack IF. Bortezomib-induced sensitization of malignant human glioma cells to vorinostat-induced apoptosis depends on reactive oxygen species production, mitochondrial dysfunction, Noxa upregulation, Mcl-1 cleavage, and DNA damage. Mol Carcinog 2011; 52:118-33. [PMID: 22086447 DOI: 10.1002/mc.21835] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 10/04/2011] [Accepted: 10/12/2011] [Indexed: 01/12/2023]
Abstract
Glioblastomas are invasive tumors with poor prognosis despite current therapies. Histone deacetylase inhibitors (HDACIs) represent a class of agents that can modulate gene expression to reduce tumor growth, and we and others have noted some antiglioma activity from HDACIs, such as vorinostat, although insufficient to warrant use as monotherapy. We have recently demonstrated that proteasome inhibitors, such as bortezomib, dramatically sensitized highly resistant glioma cells to apoptosis induction, suggesting that proteasomal inhibition may be a promising combination strategy for glioma therapeutics. In this study, we examined whether bortezomib could enhance response to HDAC inhibition in glioma cells. Although primary cells from glioblastoma multiforme (GBM) patients and established glioma cell lines did not show significant induction of apoptosis with vorinostat treatment alone, the combination of vorinostat plus bortezomib significantly enhanced apoptosis. The enhanced efficacy was due to proapoptotic mitochondrial injury and increased generation of reactive oxygen species. Our results also revealed that combination of bortezomib with vorinostat enhanced apoptosis by increasing Mcl-1 cleavage, Noxa upregulation, Bak and Bax activation, and cytochrome c release. Further downregulation of Mcl-1 using shRNA enhanced cell killing by the bortezomib/vorinostat combination. Vorinostat induced a rapid and sustained phosphorylation of histone H2AX in primary GBM and T98G cells, and this effect was significantly enhanced by co-administration of bortezomib. Vorinostat/bortezomib combination also induced Rad51 downregulation, which plays an important role in the synergistic enhancement of DNA damage and apoptosis. The significantly enhanced antitumor activity that results from the combination of bortezomib and HDACIs offers promise as a novel treatment for glioma patients.
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Affiliation(s)
- Daniel R Premkumar
- Department of Neurosurgery, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15223, USA
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202
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Small interfering RNA targeting mcl-1 enhances proteasome inhibitor-induced apoptosis in various solid malignant tumors. BMC Cancer 2011; 11:485. [PMID: 22078414 PMCID: PMC3226681 DOI: 10.1186/1471-2407-11-485] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 11/14/2011] [Indexed: 11/12/2022] Open
Abstract
Background Targeting the ubiquitin-proteasome pathway is a promising approach for anticancer strategies. Recently, we found Bik accumulation in cancer cell lines after they were treated with bortezomib. However, recent evidence indicates that proteasome inhibitors may also induce the accumulation of anti-apoptotic Bcl-2 family members. The current study was designed to analyze the levels of several anti-apoptotic members of Bcl-2 family in different human cancer cell lines after they were treated with proteasome inhibitors. Methods Different human cancer cell lines were treated with proteasome inhibitors. Western blot were used to investigate the expression of Mcl-1 and activation of mitochondrial apoptotic signaling. Cell viability was investigated using SRB assay, and induction of apoptosis was measured using flow cytometry. Results We found elevated Mcl-1 level in human colon cancer cell lines DLD1, LOVO, SW620, and HCT116; human ovarian cancer cell line SKOV3; and human lung cancer cell line H1299, but not in human breast cancer cell line MCF7 after they were treated with bortezomib. This dramatic Mcl-1 accumulation was also observed when cells were treated with other two proteasome inhibitors, MG132 and calpain inhibitor I (ALLN). Moreover, our results showed Mcl-1 accumulation was caused by stabilization of the protein against degradation. Reducing Mcl-1 accumulation by Mcl-1 siRNA reduced Mcl-1 accumulation and enhanced proteasome inhibitor-induced cell death and apoptosis, as evidenced by the increased cleavage of caspase-9, caspase-3, and poly (ADP-ribose) polymerase. Conclusions Our results showed that it was not only Bik but also Mcl-1 accumulation during the treatment of proteasome inhibitors, and combining proteasome inhibitors with Mcl-1 siRNA would enhance the ultimate anticancer effect suggesting this combination might be a more effective strategy for cancer therapy.
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203
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Hernandez-Flores G, Ortiz-Lazareno PC, Lerma-Diaz JM, Dominguez-Rodriguez JR, Jave-Suarez LF, Aguilar-Lemarroy ADC, de Celis-Carrillo R, del Toro-Arreola S, Castellanos-Esparza YC, Bravo-Cuellar A. Pentoxifylline sensitizes human cervical tumor cells to cisplatin-induced apoptosis by suppressing NF-kappa B and decreased cell senescence. BMC Cancer 2011; 11:483. [PMID: 22074157 PMCID: PMC3229613 DOI: 10.1186/1471-2407-11-483] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 11/10/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Worldwide, cervical cancer is the second most common causes of cancer in women and represents an important mortality rate. Cisplatin (CIS) is a very important antitumoral agent and can lead tumor cells toward two important cellular states: apoptosis and senescence. In some types of cancers pentoxifylline (PTX) sensitizes these cells to the toxic action of chemotherapeutics drugs such as adriamycin, inducing apoptosis. In the present work, we studied in vitro whether PTX alone or in combination with CIS induces apoptosis and/or senescence in cervix cancer HeLa and SiHa cell lines infected with HPV types 16 and 18, respectively, as well as in immortalized keratinocytyes HaCaT cells. METHODS HeLa (HPV 18+), SiHa (HPV 16+) cervix cancer cells and non-tumorigenic immortalized HaCaT cells (control) were treated with PTX, CIS or both. The cellular toxicity and survival fraction of PTX and CIS were determinate by WST-1 and clonogenic assays respectively. Apoptosis, caspase activation and phosphorylation of ERK1/2, p38, p65 (NF-κB), Bcl-2 and Bcl-XL anti-apoptotic proteins were determinated by flow cytometry. Senescence by microscopy. Phosphorylation of IκBα and IκB total were measured by ELISA. Pro-apoptotic, anti-apoptotic and senescence genes, as well as HPV-E6/7 mRNA expression, were detected by RT-PCR. RESULTS Our results show that after 24 hours of incubation PTX per se is toxic for cancer cells affecting cell viability and inducing apoptosis. The toxicity in HaCaT cells was minimal. CIS induces apoptosis in HeLa and SiHa cells and its effect was significantly increases when the cells were treated with PTX + CIS. In all studies there was a direct correlation with levels of caspases (-3, -6, -7, -9 and -8) activity and apoptosis. CIS induces important levels of senescence and phosphorylation of ERK1/2, p38, p65/RELA, and IκBα, and decreased the expression of anti-apoptotic protein Bcl-XL. Surprisingly these levels were significantly reduced by PTX in tumor cells, and at the same time, increases the expression of pro-apoptotic genes. CONCLUSION PTX sensitizes cervical cancer cells to CIS-induced apoptosis and decreases the CIS-induced senescence in these cells via inhibition of NF-κB signaling pathway; diminishes expression of antiapoptotic proteins and the activation of caspases.
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Affiliation(s)
- Georgina Hernandez-Flores
- División de Inmunología, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
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204
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Parekh S, Weniger MA, Wiestner A. New molecular targets in mantle cell lymphoma. Semin Cancer Biol 2011; 21:335-46. [PMID: 21945517 PMCID: PMC3217176 DOI: 10.1016/j.semcancer.2011.09.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 09/12/2011] [Indexed: 01/24/2023]
Abstract
Mantle cell lymphoma (MCL) is a malignancy of mature B cells characterized by aberrant expression of cyclin D1 due to the translocation t(11;14). Epigenomic and genomic lesions in pathways regulating B-cell activation, cell cycle progression, protein homeostasis, DNA damage response, cell proliferation and apoptosis contribute to its pathogenesis. While patients typically respond to first-line chemotherapy, relapse is the rule resulting in a median survival of 5-7 years. The PI3K/AKT/mTOR appears as a key pathway in the pathogenesis and can be targeted with small molecules. Most experience is with mTOR inhibitors of the rapamycin class. Second-generation mTOR inhibitors and the PI3K inhibitor CAL-101 are novel options to more effectively target this pathway. Bruton's tyrosine kinase inhibition by PCI-32765 has promising activity and indicates immunoreceptor signaling as a novel therapeutic target. Up to 50% of relapsed patients respond to the proteasome inhibitor bortezomib suggesting that MCL may be particularly sensitive to disruption of protein homeostasis and/or induction of oxidative stress. Recent work has focused on elucidating the mechanism of bortezomib-induced cytotoxicity and the development of second-generation proteasome inhibitors. DNA hypomethylating agents and histone deacetylase inhibitors effect epigenetic de-repression of aberrantly silenced genes. These epigenetic pharmaceuticals and HSP90 inhibitors can synergize with proteasome inhibitors. Finally, BH3 mimetics are emerging as tools to sensitize tumor cells to chemotherapy. Participation in clinical trials offers patients a chance to benefit from these advances and is essential to maintain the momentum of progress. Innovative trial designs may be needed to expedite the clinical development of these targeted agents.
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Affiliation(s)
- Samir Parekh
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY
| | - Marc A. Weniger
- Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Adrian Wiestner
- Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
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205
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Reovirus therapy stimulates endoplasmic reticular stress, NOXA induction, and augments bortezomib-mediated apoptosis in multiple myeloma. Oncogene 2011; 31:3023-38. [PMID: 22002308 DOI: 10.1038/onc.2011.478] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Oncolytic virotherapy with reovirus has demonstrated anti-cancer activity and minimal toxicity in clinical trials, but the mechanisms underlying these effects have not been fully elucidated. Reolysin, a proprietary formulation of reovirus for cancer therapy, stimulated selective viral replication and apoptosis in multiple myeloma (MM) cells. Reolysin-mediated apoptosis was associated with an induction of endoplasmic reticular (ER) stress-related gene expression, swelling of the endoplasmic reticulum, increases in intracellular calcium levels and a strong induction of the Bcl-2 homology 3 (BH3)-only pro-apoptotic protein NOXA. Knockdown of NOXA expression by short hairpin RNA significantly reduced the pro-apoptotic effects of Reolysin. We next showed that co-administration of Reolysin and bortezomib resulted in the dual accumulation of viral and ubiquitinated proteins, which led to enhanced ER stress, NOXA induction and apoptosis. Importantly, the combination of reovirus infection and proteasomal inhibition significantly decreased tumor burden in a xenograft and syngeneic bone disease model of MM without exhibiting adverse side effects. Our study establishes ER stress stimulation and NOXA induction as novel mediators of reovirus-induced apoptosis. Furthermore, reovirus infection can be used as a promising approach to augment the anti-myeloma activity of bortezomib by promoting additional stress to the endoplasmic reticulum of MM cells.
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206
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Kriegenburg F, Poulsen EG, Koch A, Krüger E, Hartmann-Petersen R. Redox control of the ubiquitin-proteasome system: from molecular mechanisms to functional significance. Antioxid Redox Signal 2011; 15:2265-99. [PMID: 21314436 DOI: 10.1089/ars.2010.3590] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In their natural environments, cells are regularly exposed to oxidizing conditions that may lead to protein misfolding. If such misfolded proteins are allowed to linger, they may form insoluble aggregates and pose a serious threat to the cell. Accumulation of misfolded, oxidatively damaged proteins is characteristic of many diseases and during aging. To counter the adverse effects of oxidative stress, cells can initiate an antioxidative response in an attempt to repair the damage, or rapidly channel the damaged proteins for degradation by the ubiquitin-proteasome system (UPS). Recent studies have shown that elements of the oxidative stress response and the UPS are linked on many levels. To manage the extra burden of misfolded proteins, the UPS is induced by oxidative stress, and special proteasome subtypes protect cells against oxidative damage. In addition, the proteasome is directly associated with a thioredoxin and other cofactors that may adjust the particle's response during an oxidative challenge. Here, we give an overview of the UPS and a detailed description of the degradation of oxidized proteins and of the crosstalk between oxidative stress and protein degradation in health and disease.
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Affiliation(s)
- Franziska Kriegenburg
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5,Copenhagen, Denmark
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207
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Fulda S. Novel insights into the synergistic interaction of Bortezomib and TRAIL: tBid provides the link. Oncotarget 2011; 2:418-21. [PMID: 21789791 PMCID: PMC3248183 DOI: 10.18632/oncotarget.277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The proteasome inhibitor Bortezomib has been identified as a potent enhancer of TRAIL-induced apoptosis in several human cancers. However, the identification of the underlying molecular mechanisms of this synergistic cell death induction has been ongoing over the last years. A recent study identifies a new mechanism of action for the synergism of TRAIL and Bortezomib.
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Affiliation(s)
- Simone Fulda
- Institute for Experimental Cancer Research in Pediatrics, Goethe-University Frankfurt, Komturstr. 3a, 60528 Frankfurt, Germany. Simone Fulda.
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208
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Mozos A, Roué G, López-Guillermo A, Jares P, Campo E, Colomer D, Martinez A. The expression of the endoplasmic reticulum stress sensor BiP/GRP78 predicts response to chemotherapy and determines the efficacy of proteasome inhibitors in diffuse large b-cell lymphoma. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:2601-10. [PMID: 21907693 DOI: 10.1016/j.ajpath.2011.07.031] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 07/18/2011] [Accepted: 07/25/2011] [Indexed: 01/22/2023]
Abstract
Activation of the endoplasmic reticulum (ER) stress pathway is associated with poor response to doxorubicin-containing regimens, such as rituximab, cyclophosphamide, hydroxydaunorubicin (doxorubicin), vincristine and prednisone (R-CHOP), in patients with diffuse large B-cell lymphoma (DLBCL). Bortezomib, a proteasome inhibitor, interferes with ER responses and improves survival in patients with aggressive hematologic malignant tumors, although its use in DLBCL patients remains controversial. The 78-kDa glucose-regulated protein (GRP78), also known as immunoglobulin heavy chain binding protein (BiP), is an ER stress sensor involved in the resistance to doxorubicin and bortezomib, but its role in the response to chemotherapy in DLBCL has not been explored before. We show that high BiP/GRP78 expression is related to worse overall survival (median overall survival, 5.2 versus 3.4 years). Moreover, cell death after R-CHOP in DLCBL cell lines is associated with decreased BiP/GRP78 expression. Conversely, DLBCL cell lines are primarily resistant to bortezomib, probably owing to BiP/GRP78 overexpression. Small-interfering RNA silencing of BiP/GRP78 renders all cell lines sensitive to bortezomib. R-CHOP with bortezomib (R-CHOP-BZ) reduces BiP/GRP78 expression and overcomes bortezomib resistance, mimicking the small-interfering RNA silencing of BiP/GRP78. Accordingly, R-CHOP-BZ is the most effective treatment, providing a rationale for the use of this combinational therapy to improve DLBCL patient survival. Moreover, this study provides preclinical evidence that the germinal center B-cell-like subtype DLBCL is sensitive to bortezomib combined with immunochemotherapy.
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Affiliation(s)
- Ana Mozos
- Department of Hematopathology, Hospital Clinic, IDIBAPS, University of Barcelona, Barcelona, Spain
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209
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Touzeau C, Dousset C, Bodet L, Gomez-Bougie P, Bonnaud S, Moreau A, Moreau P, Pellat-Deceunynck C, Amiot M, Le Gouill S. ABT-737 induces apoptosis in mantle cell lymphoma cells with a Bcl-2high/Mcl-1low profile and synergizes with other antineoplastic agents. Clin Cancer Res 2011; 17:5973-81. [PMID: 21821698 DOI: 10.1158/1078-0432.ccr-11-0955] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Mantle cell lymphoma (MCL) is considered to be incurable. ABT-737 is a BH3 mimetic that targets Bcl-2, which is overexpressed in MCL and implicated in drug resistance. The present work investigated the antitumor effect of ABT-737. EXPERIMENTAL DESIGN Six MCL cell lines and primary MCL cells (n = 13) were used. Sensitivity to ABT-737 was assessed, and expression levels of Bcl-2 and Mcl-1 were analyzed. Finally, ABT-737 was combined with other cytotoxic agents to promote tailored therapy. RESULTS MINO and GRANTA-519 cell lines were highly sensitive to ABT-737 [the median lethal dose (LD₅₀) = 20 and 80 nmol/L, respectively], whereas other cell lines were resistant. In primary MCL cells, 46% of patients' samples were sensitive to ABT-737. The analysis of protein expression levels revealed that both sensitive cell lines and primary MCL cells could be characterized by a Bcl-2(high)/Mcl-1(low) profile, whereas resistant MCL cells contained high levels of Mcl-1. ABT-737 induced a rapid disruption of both Bcl-2/Bax and Bcl-2/Bik complexes. In addition, silencing of Mcl-1 by siRNA sensitized MCL cell lines to ABT-737. Similarly, flavopiridol, which induces Mcl-1 downregulation, in combination with ABT-737 led to a synergistic anti-MCL effect in ABT-737-resistant cell lines. This synergy was also observed when ABT-737 was combined with either bortezomib or cytarabine. CONCLUSIONS The present work shows that ABT-737 induces strong apoptosis in MCL cells expressing a Bcl-2(high)/Mcl-1(low) profile. In ABT-737-resistant MCL cells, downregulation of Mcl-1 overcomes Mcl-1-induced resistance and synergizes ABT-737 effects. Our results strongly support the use of ABT-737 according to the Bcl-2/Mcl-1 tumor cell profiles in the treatment of MCL.
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210
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Piya S, Moon AR, Song PI, Hiscott J, Lin R, Seol DW, Kim TH. Suppression of IRF4 by IRF1, 3, and 7 in Noxa expression is a necessary event for IFN-γ-mediated tumor elimination. Mol Cancer Res 2011; 9:1356-65. [PMID: 21816905 DOI: 10.1158/1541-7786.mcr-11-0185] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
IFN-γ plays a critical role in tumor immunosurveillance by affecting either immune cells or tumor cells; however, IFN-mediated effects on tumor elimination are largely unknown. In this study, we showed that IFN regulatory factors (IRF) modulated by IFNs up- and downregulated Noxa expression, a prodeath BH3 protein, in various cancer cells. Inhibition of Noxa expression using short hairpin RNA in tumor cells leads to resistance against lipopolysaccharide (LPS)-induced tumor elimination, in which IFN-γ is known as a critical effecter in mice. Chromatin immunoprecipitation analysis in both CT26 cells and SP2/0 cells, sensitive and resistant to LPS-induced tumor elimination, respectively, revealed that the responsiveness of IRF1, 3, 4, and 7 in the Noxa promoter region in response to IFN-γ might be crucial in LPS-induced tumor elimination. IRF1, 3, and 7 were upregulated by IFN-γ and activated Noxa expression, leading to the death of Noxa wild-type baby mouse kidney (BMK) cells but not of Noxa-deficient BMK cells. In contrast, IRF4 acts as a repressor for Noxa expression and inhibits cell death induced by IRF1, 3, or 7. Therefore, although IFN-γ alone are not able to induce cell death in tumor cells in vitro, Noxa induction by IFN-γ, which is regulated by the balance between its activators (IRF1, 3, and 7) and its repressor (IRF4), is crucial to increasing the susceptibility of tumor cells to immune cell-mediated cytotoxicity.
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Affiliation(s)
- Sujan Piya
- Department of Biochemistry, Chosun University School of Medicine, Dong-Gu, Gwang-ju 501-759, Korea
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211
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Weniger MA, Rizzatti EG, Perez-Galan P, Liu D, Wang Q, Munson PJ, Raghavachari N, White T, Tweito MM, Dunleavy K, Ye Y, Wilson WH, Wiestner A. Treatment-induced oxidative stress and cellular antioxidant capacity determine response to bortezomib in mantle cell lymphoma. Clin Cancer Res 2011; 17:5101-12. [PMID: 21712452 PMCID: PMC3149767 DOI: 10.1158/1078-0432.ccr-10-3367] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
PURPOSE Proteasome inhibition disrupts protein homeostasis and induces apoptosis. Up to 50% of patients with relapsed mantle cell lymphoma (MCL) respond to bortezomib. We used gene expression profiling to investigate the connection between proteasome inhibition, cellular response, and clinical efficacy. EXPERIMENTAL DESIGN We assessed transcriptional changes in primary tumor cells from five patients during treatment with bortezomib in vivo, and in 10 MCL cell lines exposed to bortezomib in vitro, on Affymetrix microarrays. Key findings were confirmed by western blotting. RESULTS MCL cell lines exposed to bortezomib in vitro showed upregulation of endoplasmic reticulum and oxidative stress response pathways. Gene expression changes were strongest in bortezomib-sensitive cells and these cells were also more sensitive to oxidative stress induced by H2O2. Purified tumor cells obtained at several timepoints during bortezomib treatment in 5 previously untreated patients with leukemic MCL showed strong activation of the antioxidant response controlled by NRF2. Unexpectedly, activation of this homeostatic program was significantly stronger in tumors with the best clinical response. Consistent with its proapoptotic function, we found upregulation of NOXA in circulating tumor cells of responding patients. In resistant cells, gene expression changes in response to bortezomib were limited and upregulation of NOXA was absent. Interestingly, at baseline, bortezomib-resistant cells displayed a relatively higher expression of the NRF2 gene-expression signature than sensitive cells (P < 0.001). CONCLUSION Bortezomib triggers an oxidative stress response in vitro and in vivo. High cellular antioxidant capacity contributes to bortezomib resistance.
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Affiliation(s)
- Marc A. Weniger
- Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health Bethesda, MD
| | - Edgar G. Rizzatti
- Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health Bethesda, MD
- Fleury Medicina e Saude, Sao Paulo, Brazil
| | - Patricia Perez-Galan
- Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health Bethesda, MD
| | - Delong Liu
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health Bethesda, MD
| | - Qiuyan Wang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Peter J. Munson
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health Bethesda, MD
| | - Nalini Raghavachari
- Gene Expression Core Facility, Vascular Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health Bethesda, MD
| | - Therese White
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Megan M. Tweito
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Kieron Dunleavy
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Wyndham H. Wilson
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Adrian Wiestner
- Hematology Branch, National Heart, Lung and Blood Institute, National Institutes of Health Bethesda, MD
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212
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Rosebeck S, Sudini K, Chen T, Leaman DW. Involvement of Noxa in mediating cellular ER stress responses to lytic virus infection. Virology 2011; 417:293-303. [PMID: 21742363 DOI: 10.1016/j.virol.2011.06.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 05/04/2011] [Accepted: 06/13/2011] [Indexed: 01/14/2023]
Abstract
Noxa is a Bcl-2 homology domain-containing pro-apoptotic mitochondrial protein. Noxa mRNA and protein expression are upregulated by dsRNA or virus, and ectopic Noxa expression enhances cellular sensitivity to virus or dsRNA-induced apoptosis. Here we demonstrate that Noxa null baby mouse kidney (BMK) cells are deficient in normal cytopathic response to lytic viruses, and that reconstitution of the knockout cells with wild-type Noxa restored normal cytopathic responses. Noxa regulation by virus mirrored its regulation by proteasome inhibitors or ER stress inducers and the ER stress response inhibitor salubrinal protected cells against viral cytopathic effects. Noxa mRNA and protein were synergistically upregulated by IFN or dsRNA when combined with ER stress inducers, leading to Noxa/Mcl-1 interaction, activation of Bax and pro-apoptotic caspases, degradation of Mcl-1, loss of mitochondrial membrane potential and initiation of apoptosis. These data highlight the importance of ER stress in augmenting the expression of Noxa following viral infection.
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Affiliation(s)
- Shaun Rosebeck
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606, USA
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213
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Navarro A, Royo C, Hernández L, Jares P, Campo E. Molecular Pathogenesis of Mantle Cell Lymphoma: New Perspectives and Challenges With Clinical Implications. Semin Hematol 2011; 48:155-65. [DOI: 10.1053/j.seminhematol.2011.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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214
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Singh ATK, Ghosh M, Forte TM, Ryan RO, Gordon LI. Curcumin nanodisk-induced apoptosis in mantle cell lymphoma. Leuk Lymphoma 2011; 52:1537-43. [PMID: 21699455 DOI: 10.3109/10428194.2011.584253] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mantle cell lymphoma (MCL) is a pre-germinal center neoplasm characterized by cyclin D1 overexpression resulting from t(11;14)(q13;q32). Since MCL is incurable with standard lymphoma therapies, new treatment approaches are needed that target specific biologic pathways. In the present study, we investigated a novel drug delivery nanovehicle enriched with the bioactive polyphenol, curcumin (curcumin nanodisks; curcumin-ND). Cells treated with curcumin-ND showed a dose-dependent increase in apoptosis. This was accompanied by enhanced generation of reactive oxygen species (ROS). The antioxidant, N-acetylcysteine, inhibited curcumin-ND induced apoptosis, suggesting that ROS generation plays a role in curcumin action on MCL cells. Curcumin-ND decreased cyclin D1, pAkt, pIκBα, and Bcl(2) protein. In addition, enhanced FoxO3a and p27 expression as well as caspase-9, -3, and poly(ADP-ribose) polymerase (PARP) cleavage were observed. Curcumin-ND treatment led to enhanced G(1) arrest in two cultured cell models of MCL.
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Affiliation(s)
- Amareshwar T K Singh
- Division of Hematology/Oncology, Department of Medicine, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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215
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Barbone D, Ryan JA, Kolhatkar N, Chacko AD, Jablons DM, Sugarbaker DJ, Bueno R, Letai AG, Coussens LM, Fennell DA, Broaddus VC. The Bcl-2 repertoire of mesothelioma spheroids underlies acquired apoptotic multicellular resistance. Cell Death Dis 2011; 2:e174. [PMID: 21697949 PMCID: PMC3169000 DOI: 10.1038/cddis.2011.58] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Three-dimensional (3D) cultures are a valuable platform to study acquired multicellular apoptotic resistance of cancer. We used spheroids of cell lines and actual tumor to study resistance to the proteasome inhibitor bortezomib in mesothelioma, a highly chemoresistant tumor. Spheroids from mesothelioma cell lines acquired resistance to bortezomib by failing to upregulate Noxa, a pro-apoptotic sensitizer BH3-only protein that acts by displacing Bim, a pro-apoptotic Bax/Bak-activator protein. Surprisingly, despite their resistance, spheroids also upregulated Bim and thereby acquired sensitivity to ABT-737, an inhibitor of anti-apoptotic Bcl-2 molecules. Analysis using BH3 profiling confirmed that spheroids acquired a dependence on anti-apoptotic Bcl-2 proteins and were ‘primed for death'. We then studied spheroids grown from actual mesothelioma. ABT-737 was active in spheroids grown from those tumors (5/7, ∼70%) with elevated levels of Bim. Using immunocytochemistry of tissue microarrays of 48 mesotheliomas, we found that most (33, 69%) expressed elevated Bim. In conclusion, mesothelioma cells in 3D alter the expression of Bcl-2 molecules, thereby acquiring both apoptotic resistance and sensitivity to Bcl-2 blockade. Mesothelioma tumors ex vivo also show sensitivity to Bcl-2 blockade that may depend on Bim, which is frequently elevated in mesothelioma. Therefore, mesothelioma, a highly resistant tumor, may have an intrinsic sensitivity to Bcl-2 blockade that can be exploited therapeutically.
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Affiliation(s)
- D Barbone
- Lung Biology Center, San Francisco General Hospital, University of California-San Francisco, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
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216
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Cortelazzo S, Ponzoni M, Ferreri AJM, Dreyling M. Mantle cell lymphoma. Crit Rev Oncol Hematol 2011; 82:78-101. [PMID: 21658968 DOI: 10.1016/j.critrevonc.2011.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 05/02/2011] [Accepted: 05/04/2011] [Indexed: 10/25/2022] Open
Abstract
MCL is a well-characterized clinically aggressive lymphoma with a poor prognosis. Recent research findings have slightly improved the outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it does not improve overall survival with respect to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidated by ASCT ameliorates response rate and prolongs progression-free survival, but any impact on survival remains to be proven. Furthermore, the optimal timing, cytoreductive regimen and conditioning regimen, and the clinical implications of achieving a disease remission even at molecular level remain to be elucidated. The development of targeted therapies as the consequence of better dissection of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy in most patients and spare the toxicity of intense therapy in a minority of MCL patients characterized by a relatively indolent disease. Patients not eligible for intensive regimens, such as hyperC-VAD, may be considered for less demanding therapies, such as the combination of rituximab either with CHOP or with purine analogues, or bendamustine. Allogeneic SCT can be an effective option for relapsed disease in patients who are fit enough and have a compatible donor. Maintenance rituximab may be considered after response to immunochemotherapy for relapsed disease, although there are currently no data to recommend this approach as the first-line strategy. As the optimal approach to the management of MCL is still evolving, it is critical that these patients be enrolled in clinical trials to identify better treatment options.
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Affiliation(s)
- Sergio Cortelazzo
- Hematology and Bone Marrow Transplantation Unit, Azienda Ospedaliera Bolzano, Italy
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217
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Xargay-Torrent S, López-Guerra M, Saborit-Villarroya I, Rosich L, Campo E, Roué G, Colomer D. Vorinostat-induced apoptosis in mantle cell lymphoma is mediated by acetylation of proapoptotic BH3-only gene promoters. Clin Cancer Res 2011; 17:3956-68. [PMID: 21652541 DOI: 10.1158/1078-0432.ccr-10-3412] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Mantle cell lymphoma (MCL) is an aggressive B-cell neoplasm with generally poor prognosis, for which current therapies have shown limited efficacy. Vorinostat is a histone deacetylase inhibitor (HDACi) that has been approved for the treatment of cutaneous T-cell lymphoma. Our purpose was to describe the molecular mechanism whereby vorinostat induces apoptosis in MCL with particular emphasis on the role of proapoptotic BH3-only proteins. EXPERIMENTAL DESIGN The sensitivity to vorinostat was analyzed in eight MCL cell lines and primary cells from 10 MCL patients. Determination of vorinostat mechanism of action was done by flow cytometry, immunoblotting, HDAC activity assay kit, quantitative reverse transcription PCR, chromatin immunoprecipitation, and siRNA-mediated transfection. RESULTS Vorinostat inhibited total histone deacetylase activity leading to selective toxicity toward tumor cells. Vorinostat-mediated cell death implied the activation of mitochondrial apoptosis, as attested by BAX and BAK conformational changes, mitochondrial depolarization, reactive oxygen species generation, and subsequent caspase-dependent cell death. This phenomenon was linked to H4 hyperacetylation on promoter regions and consequent transcriptional activation of the proapoptotic BH3-only genes BIM, BMF, and NOXA. Selective knockdown of the three corresponding proteins rescued cells from vorinostat-induced apoptosis. Moreover, vorinostat enhanced the activity of the BH3-mimetic ABT-263 in MCL cells, leading to synergistic apoptosis induction. CONCLUSION These results indicated that transcriptional upregulation of BH3-only proteins plays an important role in the antitumoral activity of vorinostat in MCL, and that HDACi alone or in combination with BH3-mimetizing agents may represent a promising therapeutic approach for MCL patients.
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Affiliation(s)
- Sílvia Xargay-Torrent
- Hematopathology Unit, Department of Pathology, Hospital Clínic, Institut D'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Catalonia, Spain
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218
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219
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Liu Y, Ye Y. Proteostasis regulation at the endoplasmic reticulum: a new perturbation site for targeted cancer therapy. Cell Res 2011; 21:867-83. [PMID: 21537343 PMCID: PMC3203708 DOI: 10.1038/cr.2011.75] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
To deal with the constant challenge of protein misfolding in the endoplasmic reticulum (ER), eukaryotic cells have evolved an ER protein quality control (ERQC) mechanism that is integrated with an adaptive stress response. The ERQC pathway is comprised of factors residing in the ER lumen that function in the identification and retention of aberrantly folded proteins, factors in the ER membrane for retrotranslocation of misfolded polypeptides, and enzymes in the cytosol that degrade retrotranslocated proteins. The integrated stress response (termed ER stress or unfolded protein response, UPR) contains several signaling branches elicited from the ER membrane, which fine-tune the rate of protein synthesis and entry into the ER to match the ER folding capacity. The fitness of the cell, particularly those bearing a high secretory burden, is critically dependent on functional integrity of the ER, which in turn relies on these stress-attenuating mechanisms to maintain protein homeostasis, or proteostasis. Aberrant proteostasis can trigger cellular apoptosis, making these adaptive stress response systems attractive targets for perturbation in treatment of cell malignancies. Here, we review our current understanding of how the cell preserves ER proteostasis and discuss how we may harness the mechanistic information on this process to develop new cancer therapeutics.
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Affiliation(s)
- Yanfen Liu
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0540, USA
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0540, USA
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220
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Unterkircher T, Cristofanon S, Vellanki SHK, Nonnenmacher L, Karpel-Massler G, Wirtz CR, Debatin KM, Fulda S. Bortezomib primes glioblastoma, including glioblastoma stem cells, for TRAIL by increasing tBid stability and mitochondrial apoptosis. Clin Cancer Res 2011; 17:4019-30. [PMID: 21525171 DOI: 10.1158/1078-0432.ccr-11-0075] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Searching for novel approaches to sensitize glioblastoma for cell death, we investigated the proteasome inhibitor bortezomib. EXPERIMENTAL DESIGN The effect of bortezomib on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis signaling pathways was analyzed in glioblastoma cell lines, primary glioblastoma cultures, and in an in vivo model. RESULTS Bortezomib and TRAIL synergistically trigger cell death and reduce colony formation of glioblastoma cells (combination index < 0.1). Investigations into the underlying molecular mechanisms reveal that bortezomib and TRAIL act in concert to cause accumulation of tBid, the active cleavage product of Bid. Also, the stability of TRAIL-derived tBid markedly increases on proteasome inhibition. Notably, knockdown of Bid significantly decreases bortezomib- and TRAIL-mediated cell death. By comparison, silencing of Noxa, which is also upregulated by bortezomib, does not confer protection. Coinciding with tBid accumulation, the activation of Bax/Bak and loss of mitochondrial membrane potential are strongly increased in cotreated cells. Overexpression of Bcl-2 significantly reduces mitochondrial perturbations and cell death, underscoring the functional relevance of the mitochondrial pathway. In addition, bortezomib cooperates with TRAIL to reduce colony formation of glioblastoma cells, showing an effect on long-term survival. Of note, bortezomib profoundly enhances TRAIL-triggered cell death in primary cultured glioblastoma cells and in patient-derived glioblastoma stem cells, underlining the clinical relevance. Importantly, bortezomib cooperates with TRAIL to suppress tumor growth in an in vivo glioblastoma model. CONCLUSION These findings provide compelling evidence that the combination of bortezomib and TRAIL presents a promising novel strategy to trigger cell death in glioblastoma, including glioblastoma stem cells, which warrants further investigation.
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221
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Gutekunst M, Oren M, Weilbacher A, Dengler MA, Markwardt C, Thomale J, Aulitzky WE, van der Kuip H. p53 hypersensitivity is the predominant mechanism of the unique responsiveness of testicular germ cell tumor (TGCT) cells to cisplatin. PLoS One 2011; 6:e19198. [PMID: 21532991 PMCID: PMC3080918 DOI: 10.1371/journal.pone.0019198] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 03/29/2011] [Indexed: 12/20/2022] Open
Abstract
Consistent with the excellent clinical results in testicular germ cell tumors
(TGCT), most cell lines derived from this cancer show an exquisite sensitivity
to Cisplatin. It is well accepted that the high susceptibility of TGCT cells to
apoptosis plays a central role in this hypersensitive phenotype. The role of the
tumor suppressor p53 in this response, however, remains controversial. Here we
show that siRNA-mediated silencing of p53 is sufficient to completely abrogate
hypersensitivity not only to Cisplatin but also to non-genotoxic inducers of p53
such as the Mdm2 antagonist Nutlin-3 and the proteasome inhibitor Bortezomib.
The close relationship between p53 protein levels and induction of apoptosis is
lost upon short-term differentiation, indicating that this predominant
pro-apoptotic function of p53 is unique in pluripotent embryonal carcinoma (EC)
cells. RNA interference experiments as well as microarray analysis demonstrated
a central role of the pro-apoptotic p53 target gene NOXA in the p53-dependent
apoptotic response of these cells. In conclusion, our data indicate that the
hypersensitivity of TGCT cells is a result of their unique sensitivity to p53
activation. Furthermore, in the very specific cellular context of germ
cell-derived pluripotent EC cells, p53 function appears to be limited to
induction of apoptosis.
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Affiliation(s)
- Matthias Gutekunst
- Dr Margarete-Fischer-Bosch Institute of Clinical Pharmacology and
University of Tuebingen, Stuttgart, Germany
| | - Moshe Oren
- Department of Molecular Cell Biology, Weizmann Institute of Science,
Rehovot, Israel
| | - Andrea Weilbacher
- Dr Margarete-Fischer-Bosch Institute of Clinical Pharmacology and
University of Tuebingen, Stuttgart, Germany
| | - Michael A. Dengler
- Dr Margarete-Fischer-Bosch Institute of Clinical Pharmacology and
University of Tuebingen, Stuttgart, Germany
| | - Christiane Markwardt
- Dr Margarete-Fischer-Bosch Institute of Clinical Pharmacology and
University of Tuebingen, Stuttgart, Germany
| | - Jürgen Thomale
- Institute for Cell Biology, University of Duisburg-Essen Medical School,
Essen, Germany
| | - Walter E. Aulitzky
- 2 Department of Internal Medicine, Robert-Bosch-Hospital, Stuttgart,
Germany
| | - Heiko van der Kuip
- Dr Margarete-Fischer-Bosch Institute of Clinical Pharmacology and
University of Tuebingen, Stuttgart, Germany
- * E-mail:
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Naumann I, Kappler R, von Schweinitz D, Debatin KM, Fulda S. Bortezomib Primes Neuroblastoma Cells for TRAIL-Induced Apoptosis by Linking the Death Receptor to the Mitochondrial Pathway. Clin Cancer Res 2011; 17:3204-18. [DOI: 10.1158/1078-0432.ccr-10-2451] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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223
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Smith AJ, Dai H, Correia C, Takahashi R, Lee SH, Schmitz I, Kaufmann SH. Noxa/Bcl-2 protein interactions contribute to bortezomib resistance in human lymphoid cells. J Biol Chem 2011; 286:17682-92. [PMID: 21454712 DOI: 10.1074/jbc.m110.189092] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Previous studies have suggested that the BH3 domain of the proapoptotic Bcl-2 family member Noxa only interacts with the anti-apoptotic proteins Mcl-1 and A1 but not Bcl-2. In view of the similarity of the BH3 binding domains of these anti-apoptotic proteins as well as recent evidence that studies of isolated BH3 domains can potentially underestimate the binding between full-length Bcl-2 family members, we examined the interaction of full-length human Noxa with anti-apoptotic human Bcl-2 family members. Surface plasmon resonance using bacterially expressed proteins demonstrated that Noxa binds with mean dissociation constants (K(D)) of 3.4 nm for Mcl-1, 70 nm for Bcl-x(L), and 250 nm for wild type human Bcl-2, demonstrating selectivity but not absolute specificity of Noxa for Mcl-1. Further analysis showed that the Noxa/Bcl-2 interaction reflected binding between the Noxa BH3 domain and the Bcl-2 BH3 binding groove. Analysis of proteins expressed in vivo demonstrated that Noxa and Bcl-2 can be pulled down together from a variety of cells. Moreover, when compared with wild type Bcl-2, certain lymphoma-derived Bcl-2 mutants bound Noxa up to 20-fold more tightly in vitro, pulled down more Noxa from cells, and protected cells against killing by transfected Noxa to a greater extent. When killing by bortezomib (an agent whose cytotoxicity in Jurkat T-cell leukemia cells is dependent on Noxa) was examined, apoptosis was enhanced by the Bcl-2/Bcl-x(L) antagonist ABT-737 or by Bcl-2 down-regulation and diminished by Bcl-2 overexpression. Collectively, these observations not only establish the ability of Noxa and Bcl-2 to interact but also identify Bcl-2 overexpression as a potential mechanism of bortezomib resistance.
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Affiliation(s)
- Alyson J Smith
- Department of Molecular Pharmacology, Mayo Clinic, Rochester, Minnesota 55905, USA
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Park WH. Mitogen-activated protein kinase inhibitors differently affect the growth inhibition and death of a proteasome inhibitor, MG132-treated human pulmonary fibroblast cells. Hum Exp Toxicol 2011; 30:1945-54. [PMID: 21421692 DOI: 10.1177/0960327111403173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Carbobenzoxy-Leu-Leu-leucinal (MG132) as a proteasome inhibitor can induce growth inhibition and death in lung cancer or normal cells. However, little is known about relationship between proteasome inhibition and mitogen-activated protein kinase (MAPK) signaling in normal lung cells. Thus, in the present study, we investigated the effects of MAPK inhibitors on MG132-treated human pulmonary fibroblast (HPF) cells in relation to cell growth inhibition, cell death, reactive oxygen species (ROS) and glutathione (GSH). Treatment with 15 μM MG132 increased ROS levels including mitochondrial O(2•)(-) and GSH depleted cell numbers in HPF cells at 24 hours. MAP kinase or ERK kinase (MEK) inhibitor did not significantly affect cell growth inhibition, cell death, the loss of mitochondrial membrane potential (MMP; ΔΨ(m)), ROS level and GSH depletion in MG132-treated HPF cells. c-Jun N-terminal kinase (JNK) inhibitor attenuated the growth inhibition and death by MG132. This inhibitor also significantly decreased O(2•)(-) level in MG132-treated HPF cells. Although p38 inhibitor slightly enhanced HPF cell growth inhibition by MG132, this inhibitor and siRNA prevented HPF cell death induced by MG132. p38 inhibitor also attenuated d O(2•)(-) level and GSH depletion. Moreover, extracellular signal regulated kinase (ERK), JNK or p38 siRNA did not strongly affect ROS levels in MG132-treated HPF cells. ERK and JNK siRNAs decreased anonymous ubiquitinated protein levels in MG132-treated HPF cells. In conclusion, MAPK inhibitors differently affected the growth inhibition and death of MG132-treated HPF cells. Especially, p38 inhibitor attenuated HPF cell death by MG132, which was in part related to changes in ROS and GSH levels.
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Affiliation(s)
- Woo Hyun Park
- Department of Physiology, Medical School, Institute for Medical Sciences, Chonbuk National University, JeonJu, Republic of Korea.
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225
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Cross B, Chen L, Cheng Q, Li B, Yuan ZM, Chen J. Inhibition of p53 DNA binding function by the MDM2 protein acidic domain. J Biol Chem 2011; 286:16018-29. [PMID: 21454483 DOI: 10.1074/jbc.m111.228981] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MDM2 regulates p53 predominantly by promoting p53 ubiquitination. However, ubiquitination-independent mechanisms of MDM2 have also been implicated. Here we show that MDM2 inhibits p53 DNA binding activity in vitro and in vivo. MDM2 binding promotes p53 to adopt a mutant-like conformation, losing reactivity to antibody Pab1620, while exposing the Pab240 epitope. The acidic domain of MDM2 is required to induce p53 conformational change and inhibit p53 DNA binding. Alternate reading frame binding to the MDM2 acidic domain restores p53 wild type conformation and rescues DNA binding activity. Furthermore, histone methyl transferase SUV39H1 binding to the MDM2 acidic domain also restores p53 wild type conformation and allows p53-MDM2-SUV39H1 complex to bind DNA. These results provide further evidence for an ubiquitination-independent mechanism of p53 regulation by MDM2 and reveal how MDM2-interacting repressors gain access to p53 target promoters and repress transcription. Furthermore, we show that the MDM2 inhibitor Nutlin cooperates with the proteasome inhibitor Bortezomib by stimulating p53 DNA binding and transcriptional activity, providing a rationale for combination therapy using proteasome and MDM2 inhibitors.
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Affiliation(s)
- Brittany Cross
- Molecular Oncology Department, Moffitt Cancer Center, Tampa, Florida 33612, USA
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226
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Yang G, Jiang Y, Rao K, Chen X, Wang Q, Liu A, Xiong W, Yuan J. Mitochondrial dysfunction and transactivation of p53-dependent apoptotic genes in BaP-treated human fetal lung fibroblasts. Hum Exp Toxicol 2011; 30:1904-13. [DOI: 10.1177/0960327111401637] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Benzo(a)pyrene (BaP) has been shown to be an inducer of apoptosis. However, mechanisms involved in BaP-induced mitochondrial dysfunction are not well-known. In this study, human fetal lung fibroblasts cells were treated with BaP (8, 16, 32, 64 and 128 μM) for 4 and 12 h. Cell viability, intracellular level of reactive oxygen species (ROS), total antioxidant capacity (T-AOC), mitochondrial membrane potential (Δ Ψm) and cytochrome c release were determined. Changes in transcriptional levels of p53-dependent apoptotic genes ( p53, APAF1, CASPASE3, CASPASE9, NOXA and PUMA) were measured. At time point of 4 h, BaP induced the intracellular ROS generation in 64 ( p < .05) and 128 μM BaP groups ( p < .01) but decreased the T-AOC activities in 32, 64 ( p < .05 for both) and 128 μM BaP groups ( p < .01). At time point of 12 h, Δ Ψm significantly decreased in ≥32 μM BaP groups ( p < .05 for all). Amount of mitochondrial cytochrome c significantly increased in 128 μM BaP group ( p < .01). Transcriptional levels of CASPASE3, CASPASE9, APAF1 and PUMA were up-regulated in all BaP groups ( p < .05 for all) and in ≥32 μM groups for NOXA ( p < .05). But only in 16 μM BaP group a relatively little expression of p53 mRNA was observed ( p < .05). The results indicate that in the earlier period BaP promoted the generation of excessive ROS and subsequently the mitochondrial depolarization, whereas transactivations of the p53-dependent apoptotic genes were significantly induced at the later period.
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Affiliation(s)
- Guangtao Yang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Jiang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kaimin Rao
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xi Chen
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qian Wang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ailin Liu
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Xiong
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Yuan
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The MOE Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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227
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Rushworth SA, Bowles KM, MacEwan DJ. High basal nuclear levels of Nrf2 in acute myeloid leukemia reduces sensitivity to proteasome inhibitors. Cancer Res 2011; 71:1999-2009. [PMID: 21212410 DOI: 10.1158/0008-5472.can-10-3018] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Proteasome inhibitors such as bortezomib exhibit clinical efficacy in multiple myeloma, but studies in acute myeloid leukemia (AML) have been disappointing to date. The apparent failure in AML likely reflects a lack of biological understanding that might clarify applications of proteosome inhibitors in this disease. Here we show that AML cells are considerably less sensitive than control noncancerous cells to bortezomib-induced cytotoxicity, permitting most bortezomib-treated AML cells to survive treatment. We traced reduced bortezomib sensitivity to increased basal levels of nuclear Nrf2, a transcription factor that stimulates protective antioxidant enzymes. Bortezomib stimulates cytotoxicity through accumulation of reactive oxygen species (ROS) but elevated basal levels of nuclear Nrf2 present in AML cells reduced ROS levels, permitting AML cells to survive drug treatment. We further found that the Nrf2 transcriptional repressor Bach1 is rapidly inactivated by bortezomib, allowing rapid induction of Nrf2-regulated cytoprotective and detoxification genes that protect AML cells from bortezomib-induced apoptosis. By contrast, nonmalignant control cells lacked constitutive activation of Nrf2, such that bortezomib-mediated inactivation of Bach1 led to a delay in induction of Nrf2-regulated genes, effectively preventing the manifestation of apoptotic protection that is seen in AML cells. Together, our findings argue that AML might be rendered sensitive to proteasome inhibitors by cotreatment with either an Nrf2-inhibitory or Bach1-inhibitory treatment, rationalizing a targeted therapy against AML.
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228
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Lowman XH, McDonnell MA, Kosloske A, Odumade OA, Jenness C, Karim CB, Jemmerson R, Kelekar A. The proapoptotic function of Noxa in human leukemia cells is regulated by the kinase Cdk5 and by glucose. Mol Cell 2011; 40:823-33. [PMID: 21145489 DOI: 10.1016/j.molcel.2010.11.035] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 08/20/2010] [Accepted: 10/05/2010] [Indexed: 01/11/2023]
Abstract
The BH3-only protein, Noxa, is induced in response to apoptotic stimuli, such as DNA damage, hypoxia, and proteasome inhibition in most human cells. Noxa is constitutively expressed in proliferating cells of hematopoietic lineage and required for apoptosis in response to glucose stress. We show that Noxa is phosphorylated on a serine residue (S(13)) in the presence of glucose. Phosphorylation promotes its cytosolic sequestration and suppresses its apoptotic function. We identify Cdk5 as the Noxa kinase and show that Cdk5 knockdown or expression of a Noxa S(13) to A mutant increases sensitivity to glucose starvation, confirming that the phosphorylation is protective. Both glucose deprivation and Cdk5 inhibition promote apoptosis by dephosphorylating Noxa. Paradoxically, Noxa stimulates glucose consumption and may enhance glucose turnover via the pentose phosphate pathway rather than through glycolysis. We propose that Noxa plays both growth-promoting and proapoptotic roles in hematopoietic cancers with phospho-S(13) as the glucose-sensitive toggle switch controlling these opposing functions.
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Affiliation(s)
- Xazmin H Lowman
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
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229
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Han YH, Kim SZ, Kim SH, Park WH. Reactive oxygen species and glutathione level changes by a proteasome inhibitor, MG132, partially affect calf pulmonary arterial endothelial cell death. Drug Chem Toxicol 2011; 33:403-9. [PMID: 20088736 DOI: 10.3109/01480540903524350] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
MG132 as a proteasome inhibitor has been shown to induce apoptotic cell death through the formation of reactive oxygen species (ROS). Here, we evaluated the effects of MG132 on the growth of endothelial cells (ECs), especially calf pulmonary artery endothelial cells (CPAECs), in relation to cell death, ROS, and glutathione (GSH) levels. MG132 dose dependently inhibited the growth of CPAEC and human umbilical vein endothelial cells (HUVECs) at 24 hours. MG132 also induced apoptotic cell death in CPAEC, which were accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)). MG132 increased ROS levels, including O(2)(*-) in CPAEC, but not in HUVEC. MG132 also dose dependently increased GSH-depleted cells in both ECs. N-acetyl-cysteine (NAC; a well-known antioxidant) reduced ROS levels in MG132-treated CPAEC with the slight prevention of cell death and GSH depletion. Buthionine sulfoximine (BSO; an inhibitor of GSH synthesis) increased ROS levels and decreased GSH levels in MG132-treated CPAEC without the enhancement of cell death. In conclusion, MG132 inhibited the growth of ECs, especially CPAEC. The changes of ROS and GSH levels by MG132 partially affect CPAEC death.
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Affiliation(s)
- Yong Hwan Han
- Department of Physiology, Medical School, Research Institute of Clinical Medicine, Center for Healthcare Technology Development Chonbuk National University, JeonJu, Republic of Korea
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Jin L, Tabe Y, Kojima K, Zhou Y, Pittaluga S, Konopleva M, Miida T, Raffeld M. MDM2 antagonist Nutlin-3 enhances bortezomib-mediated mitochondrial apoptosis in TP53-mutated mantle cell lymphoma. Cancer Lett 2010; 299:161-70. [PMID: 20850924 DOI: 10.1016/j.canlet.2010.08.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 08/16/2010] [Accepted: 08/23/2010] [Indexed: 02/03/2023]
Abstract
This study demonstrated a pronounced synergistic growth-inhibitory effect of an MDM2 inhibitor Nutlin-3 and a proteasome inhibitor bortezomib in mantle cell lymphoma (MCL) cells regardless of TP53 mutant status and innate bortezomib sensitivity. In the mutant TP53 MCL cells which are intrinsically resistant to bortezomib, the combination of Nutlin-3/bortezomib synergistically induced cytotoxicity through the mitochondrial apoptotic pathway mediated by transcription-independent upregulation of NOXA, sequestration of MCL-1, activation of BAX, BAK, caspase-9 and -3. In the bortezomib sensitive wild-type TP53 MCL cells, the Nutlin-3/bortezomib combination caused G0/G1 cell cycle arrest followed by the increase in apoptosis induction. These findings indicate potential therapeutic efficacy of Nutlin-3/bortezomib combination for the treatment of chemorefractory MCL.
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Affiliation(s)
- Linhua Jin
- Department of Clinical Pathology, Juntendo University School of Medicine, Tokyo, Japan
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231
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Pandit B, Gartel AL. Proteasome inhibitors induce p53-independent apoptosis in human cancer cells. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 178:355-60. [PMID: 21224072 DOI: 10.1016/j.ajpath.2010.11.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 08/03/2010] [Accepted: 09/14/2010] [Indexed: 11/18/2022]
Abstract
Proteasome inhibitors are used against human cancer, but their mechanisms of action are not entirely understood. For example, the role of the tumor suppressor p53 is controversial. We reevaluated the role of p53 in proteasome inhibitor-induced apoptosis by using isogenic human cancer cell lines with different p53 status. We found that well-known proteasome inhibitors such as MG132 and bortezomib, as well as the recently discovered proteasome inhibitor thiostrepton, induced p53-independent apoptosis in human cancer cell lines that correlated with p53-independent induction of proapoptotic Noxa but not Puma protein. In addition, these drugs inhibited growth of several cancer cell lines independently of p53 status. Notably, thiostrepton induced more potent apoptosis in HepG2 cells with p53 knockdown than in parental cells with wild-type p53. Our data confirm that proteasome inhibitors generally induce p53-independent apoptosis in human cancer cells.
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Affiliation(s)
- Bulbul Pandit
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
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232
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Noxa mediates p18INK4c cell-cycle control of homeostasis in B cells and plasma cell precursors. Blood 2010; 117:2179-88. [PMID: 21163929 DOI: 10.1182/blood-2010-06-288027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Inhibition of Cdk4/Cdk6 by p18(INK4c) (p18) is pivotal for generation of noncycling immunoglobulin (Ig)-secreting plasma cells (PCs). In the absence of p18, CD138(+) plasmacytoid cells continue to cycle and turnover rapidly, suggesting that p18 controls PC homeostasis. We now show that p18 selectively acts in a rare population of rapidly cycling CD138(hi)/B220(hi) intermediate PCs (iPCs). While retaining certain B-cell signatures, iPCs are poised to differentiate to end-stage PCs although the majority undergo apoptosis. p18 is dispensable for the development of the PC transcriptional circuitry, and Blimp-1 and Bcl-6 are expressed fully and mutually exclusively in individual iPCs. However, a minor proportion of iPCs express both, and they are preferentially protected by p18 or Bcl-xL overexpression, consistent with expansion of the iPC pool by Bcl-xL overexpression, or loss of proapoptotic Bim or Noxa. Expression of Noxa is induced during B-cell activation, peaks in iPCs, and selectively repressed by p18. It is required to promote apoptosis of cycling B cells, especially in the absence of p18. These findings define the first physiologic function for Noxa and suggest that by repressing Noxa, induction of G₁ arrest by p18 bypasses a homeostatic cell-cycle checkpoint in iPCs for PC differentiation.
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233
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Natural proteasome inhibitor celastrol suppresses androgen-independent prostate cancer progression by modulating apoptotic proteins and NF-kappaB. PLoS One 2010; 5:e14153. [PMID: 21170316 PMCID: PMC3000808 DOI: 10.1371/journal.pone.0014153] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Accepted: 11/10/2010] [Indexed: 01/15/2023] Open
Abstract
Background Celastrol is a natural proteasome inhibitor that exhibits promising anti-tumor effects in human malignancies, especially the androgen-independent prostate cancer (AIPC) with constitutive NF-κB activation. Celastrol induces apoptosis by means of proteasome inhibition and suppresses prostate tumor growth. However, the detailed mechanism of action remains elusive. In the current study, we aim to test the hypothesis that celastrol suppresses AIPC progression via inhibiting the constitutive NF-κB activity as well as modulating the Bcl-2 family proteins. Methodology/Principal Findings We examined the efficacy of celastrol both in vitro and in vivo, and evaluated the role of NF-κB in celastrol-mediated AIPC regression. We found that celastrol inhibited cell proliferation in all three AIPC cell lines (PC-3, DU145 and CL1), with IC50 in the range of 1–2 µM. Celastrol also suppressed cell migration and invasion. Celastrol significantly induced apoptosis as evidenced by increased sub-G1 population, caspase activation and PARP cleavage. Moreover, celastrol promoted cleavage of the anti-apoptotic protein Mcl-1 and activated the pro-apoptotic protein Noxa. In addition, celastrol rapidly blocked cytosolic IκBα degradation and nuclear translocation of RelA. Likewise, celastrol inhibited the expression of multiple NF-κB target genes that are involved in proliferation, invasion and anti-apoptosis. Celastrol suppressed AIPC tumor progression by inhibiting proliferation, increasing apoptosis and decreasing angiogenesis, in PC-3 xenograft model in nude mouse. Furthermore, increased cellular IκBα and inhibited expression of various NF-κB target genes were observed in tumor tissues. Conclusions/Significance Our data suggest that, via targeting the proteasome, celastrol suppresses proliferation, invasion and angiogenesis by inducing the apoptotic machinery and attenuating constitutive NF-κB activity in AIPC both in vitro and in vivo. Celastrol as an active ingredient of traditional herbal medicine could thus be developed as a new therapeutic agent for hormone-refractory prostate cancer.
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234
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Antiproliferative and proapoptotic activity of GUT-70 mediated through potent inhibition of Hsp90 in mantle cell lymphoma. Br J Cancer 2010; 104:91-100. [PMID: 21139584 PMCID: PMC3039813 DOI: 10.1038/sj.bjc.6606007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Background: Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma with poor prognosis, requiring novel anticancer strategies. Methods: Mantle cell lymphoma cell lines with known p53 status were treated with GUT-70, a tricyclic coumarin derived from Calophyllum brasiliense, and the biological and biochemical consequences of GUT-70 were studied. Results: GUT-70 markedly reduced cell proliferation/viability through G1 cell cycle arrest and increased apoptosis, with greater sensitivity in mutant (mt)-p53-expressing MCL cells than in wild-type (wt)-p53-bearing cells. Mechanistically, GUT-70 showed binding affinity to heat-shock protein 90 (Hsp90) and ubiquitin-dependent proteasomal degradation of Hsp90 client proteins, including cyclin D1, Raf-1, Akt, and mt-p53. Depletion of constitutively overexpressed cyclin D1 by GUT-70 was accompanied by p27 accumulation and decreased Rb phosphorylation. GUT-70 induced mitochondrial apoptosis with Noxa upregulation and Mcl-1 downregulation in mt-p53 cells, but Mcl-1 accumulation in wt-p53 cells. Noxa and Mcl-1 were coimmunoprecipitated, and activated BAK. Treatment with a combination of GUT-70 and bortezomib or doxorubicin had synergistic antiproliferative effects in MCL cells that were independent of p53 status. Conclusion: GUT-70 has pronounced antiproliferative effects in MCL with mt-p53, a known negative prognostic factor for MCL, through Hsp90 inhibition. These findings suggest that GUT-70 has potential utility for the treatment of MCL.
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235
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The Hsp90 inhibitor IPI-504 overcomes bortezomib resistance in mantle cell lymphoma in vitro and in vivo by down-regulation of the prosurvival ER chaperone BiP/Grp78. Blood 2010; 117:1270-9. [PMID: 21106982 DOI: 10.1182/blood-2010-04-278853] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Despite the promising introduction of the proteasome inhibitor bortezomib in the treatment of mantle cell lymphoma (MCL), not all patients respond, and resistance often appears after initial treatment. By analyzing a set of 18 MCL samples, including cell lines with constitutive or induced resistance to bortezomib, we found a high correlation between loss of sensitivity to the proteasome inhibitor and up-regulation of the prosurvival chaperone BiP/Grp78. BiP/Grp78 stabilization was ensured at a posttranscriptional level by an increase in the chaperoning activity of heat shock protein of 90 kDa (Hsp90). In bortezomib-resistant cells, both BiP/Grp78 knockdown and cell pretreatment with the Hsp90 inhibitor of the ansamycin class, IPI-504, led to synergistic induction of apoptotic cell death when combined with bortezomib. Cell exposure to the IPI-504-bortezomib combination provoked the dissociation of Hsp90/BiP complexes, leading to BiP/Grp78 depletion, inhibition of unfolded protein response, and promotion of NOXA-mediated mitochondrial depolarization. The IPI-504-bortezomib combination also prevented BiP/Grp78 accumulation, thereby promoting apoptosis and inhibiting the growth of bortezomib-resistant tumors in a mouse model of MCL xenotransplantation. These results suggest that targeting unfolded protein response activation by the inhibition of Hsp90 may be an attractive model for the design of a new bortezomib-based combination therapy for MCL.
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236
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Proteasomal degradation is transcriptionally controlled by TCF11 via an ERAD-dependent feedback loop. Mol Cell 2010; 40:147-58. [PMID: 20932482 DOI: 10.1016/j.molcel.2010.09.012] [Citation(s) in RCA: 267] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 06/14/2010] [Accepted: 07/20/2010] [Indexed: 11/22/2022]
Abstract
Coordinated regulation of the ubiquitin-proteasome system (UPS) is crucial for the cell to adjust its protein degradation capacity to changing proteolytic requirements. We have shown previously that mammalian cells upregulate proteasome gene expression in response to proteasome inhibition. Here, we report the identification of the transcription factor TCF11 (long isoform of Nrf1) as a key regulator for 26S proteasome formation in human cells to compensate for reduced proteolytic activity. Under noninducing conditions, TCF11 resides in the endoplasmic reticulum (ER) membrane. There, TCF11 is targeted to ER-associated protein degradation requiring the E3 ubiquitin ligase HRD1 and the AAA ATPase p97. Proteasome inhibitors trigger the accumulation of oxidant-damaged proteins and promote the nuclear translocation of TCF11 from the ER, permitting activation of proteasome gene expression by binding to antioxidant response elements in their promoter regions. Thus, we uncovered the transcriptional control loop regulating human proteasome-dependent protein degradation to counteract proteotoxic stress caused by proteasome inhibition.
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237
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Bortezomib resistance in mantle cell lymphoma is associated with plasmacytic differentiation. Blood 2010; 117:542-52. [PMID: 20956803 DOI: 10.1182/blood-2010-02-269514] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Bortezomib induces remissions in 30%-50% of patients with relapsed mantle cell lymphoma (MCL). Conversely, more than half of patients' tumors are intrinsically resistant to bortezomib. The molecular mechanism of resistance has not been defined. We generated a model of bortezomib-adapted subclones of the MCL cell lines JEKO and HBL2 that were 40- to 80-fold less sensitive to bortezomib than the parental cells. Acquisition of bortezomib resistance was gradual and reversible. Bortezomib-adapted subclones showed increased proteasome activity and tolerated lower proteasome capacity than the parental lines. Using gene expression profiling, we discovered that bortezomib resistance was associated with plasmacytic differentiation, including up-regulation of IRF4 and CD38 and expression of CD138. In contrast to plasma cells, plasmacytic MCL cells did not increase immunoglobulin secretion. Intrinsically bortezomib-resistant MCL cell lines and primary tumor cells from MCL patients with inferior clinical response to bortezomib also expressed plasmacytic features. Knockdown of IRF4 was toxic for the subset of MCL cells with plasmacytic differentiation, but only slightly sensitized cells to bortezomib. We conclude that plasmacytic differentiation in the absence of an increased secretory load can enable cells to withstand the stress of proteasome inhibition. Expression of CD38 and IRF4 could serve as markers of bortezomib resistance in MCL. This study has been registered at http://clinicaltrials.gov as NCT00131976.
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238
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You BR, Park WH. MG132, a proteasome inhibitor-induced calf pulmonary arterial endothelial cell growth and death, are changed by MAPK inhibitors. Drug Chem Toxicol 2010; 34:45-52. [PMID: 20954830 DOI: 10.3109/01480545.2010.494663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
MG132, as a proteasome inhibitor, has been shown to induce apoptotic cell death through the formation of reactive oxygen species (ROS). In this study, we investigated the effects of MAPK inhibitors on MG132-treated calf pulmonary artery endothelial cells (CPAECs) in relation to cell death, ROS, and glutathione (GSH). MG132 inhibited the growth of CPAEC and also induced apoptosis, which was accompanied by the loss of mitochondrial membrane potential (MMP; ΔΨ(m)). MG132 increased ROS levels and GSH-depleted cell numbers in CPAEC. Treatment with MAPK (MEK, JNK, and p38) inhibitors showed a slight enhancement of cell-growth inhibition by MG132. All the MAPK inhibitors decreased cell death by MG132. Especially, the JNK inhibitor showed a strong effect. They all did not affect ROS levels and GSH depletion in MG132-treated CPAEC, but increased ROS and GSH levels in MG132-untreated CPAEC. In conclusion, MG132 induced apoptosis in CPAEC, which was accompanied by ROS increase and GSH depletion. The changes of MG132-induced CPAEC growth inhibition and death by MAPK inhibitors were not tightly correlated to ROS and GSH levels.
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Affiliation(s)
- Bo Ra You
- Department of Physiology, Medical School, Institute for Medical Sciences Chonbuk National University, JeonJu, 561-180, Republic of Korea
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239
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Mantle cell lymphoma: biology, pathogenesis, and the molecular basis of treatment in the genomic era. Blood 2010; 117:26-38. [PMID: 20940415 DOI: 10.1182/blood-2010-04-189977] [Citation(s) in RCA: 300] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mantle cell lymphoma (MCL) is a B-cell non-Hodgkin lymphoma of which at least a subset arises from antigen-experienced B cells. However, what role antigen stimulation plays in its pathogenesis remains ill defined. The genetic hallmark is the chromosomal translocation t(11;14) resulting in aberrant expression of cyclin D1. Secondary genetic events increase the oncogenic potential of cyclin D1 and frequently inactivate DNA damage response pathways. In combination these changes drive cell-cycle progression and give rise to pronounced genetic instability. Several signaling pathways contribute to MCL pathogenesis, including the often constitutively activated PI3K/AKT/mTOR pathway, which promotes tumor proliferation and survival. WNT, Hedgehog, and NF-κB pathways also appear to be important. Although MCL typically responds to frontline chemotherapy, it remains incurable with standard approaches. Proteasome inhibitors (bortezomib), mTOR inhibitors (temsirolimus), and immunomodulatory drugs (lenalidomide) have recently been added to the treatment options in MCL. The molecular basis for the antitumor activity of these agents is an area of intense study that hopefully will lead to further improvements in the near future. Given its unique biology, relative rarity, and the difficulty in achieving long-lasting remissions with conventional approaches, patients with MCL should be encouraged to participate in clinical trials.
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240
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Distinct molecular mechanisms responsible for bortezomib-induced death of therapy-resistant versus -sensitive B-NHL cells. Blood 2010; 116:5605-14. [PMID: 20930068 DOI: 10.1182/blood-2009-12-259754] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Resistance to currently available therapies is a major impediment to the successful treatment of hematological malignancies. Here, we used a model of therapy-resistant B-cell non Hodgkin lymphoma (B-NHL) developed in our laboratory along with primary B-NHL cells to study basic mechanisms of bortezomib activity. In resistant cells and a subset of primary B-NHLs, bortezomib treatment led to stabilization of Bak and subsequent Bak-dependent activation of apoptosis. In contrast to sensitive cells that die strictly by apoptosis, bortezomib was capable of killing resistant cells through activation of apoptosis or caspase-independent mechanism(s) when caspases were pharmacologically inhibited. Our data demonstrate that bortezomib is capable of killing B-NHL cells via multiple mechanisms, regardless of their basal apoptotic potential, and contributes to growing evidence that proteasome inhibitors can act via modulation of B-cell lymphoma 2 (Bcl-2) family proteins. The capacity of bortezomib to act independently of the intrinsic apoptotic threshold of a given B-NHL cell suggests that bortezomib-based therapies could potentially overcome resistance and result in relevant clinical activity in a relapsed/refractory setting.
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241
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Chari A, Mazumder A, Jagannath S. Proteasome inhibition and its therapeutic potential in multiple myeloma. Biologics 2010; 4:273-87. [PMID: 21116326 PMCID: PMC2990320 DOI: 10.2147/btt.s3419] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Due to an unmet clinical need for treatment, the first in class proteasome inhibitor, bortezomib, moved from drug discovery to FDA approval in multiple myeloma in an unprecedented eight years. In the wake of this rapid approval arose a large number of questions about its mechanism of action and toxicity as well as its ultimate role in the treatment of this disease. In this article, we briefly review the preclinical and clinical development of the drug as the underpinning for a systematic review of the large number of clinical trials that are beginning to shed some light on the full therapeutic potential of bortezomib in myeloma. We conclude with our current understanding of the mechanism of action of this agent and a discussion of the novel proteasome inhibitors under development, as it will be progress in these areas that will ultimately determine the true potential of proteasome inhibition in myeloma.
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Affiliation(s)
- Ajai Chari
- Mount Sinai School of Medicine, New York, NY, USA
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242
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Reddy N, Czuczman M. Enhancing activity and overcoming chemoresistance in hematologic malignancies with bortezomib: preclinical mechanistic studies. Ann Oncol 2010; 21:1756-1764. [DOI: 10.1093/annonc/mdq009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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243
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Chen R, Chubb S, Cheng T, Hawtin RE, Gandhi V, Plunkett W. Responses in mantle cell lymphoma cells to SNS-032 depend on the biological context of each cell line. Cancer Res 2010; 70:6587-97. [PMID: 20663900 DOI: 10.1158/0008-5472.can-09-3578] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
SNS-032 is a potent inhibitor of cyclin-dependent kinases (Cdk) 2, 7, and 9 that regulate the cell cycle and transcription. Our studies in indolent primary chronic lymphocytic leukemia cells showed that SNS-032 inhibited transcription, diminished the antiapoptotic protein Mcl-1, and induced apoptosis. The present study focuses on evaluating this compound in four proliferating mantle cell lymphoma lines (Jeko-1, Granta 519, Mino, and SP-53). Consistent with its action against Cdk9 and Cdk7, SNS-032 inhibited the phosphorylation of RNA pol II in all four lines and blocked RNA synthesis. The transcripts and protein levels of short-lived proteins decreased, including cyclin D1 and Mcl-1. Cell growth was inhibited in a concentration-dependent manner in all lines. Apoptosis was induced in JeKo-1, Mino, and SP-53 cells without disrupting cell cycle distribution. However, apoptosis was limited in Granta cells; rather, there was a significant reduction of clonogenic survival. Small interfering RNA was used to specifically knock down Mcl-1 and cyclin D1 in JeKo-1 and Granta cells. Knocking down Mcl-1 induced significant apoptosis in Jeko-1 cells but not Granta cells. Reducing cyclin D1, rather than Mcl-1, was associated with loss of clonogenic survival in Granta cells. Thus, these results indicated that mantle cell lymphoma cell lines have distinct mechanisms sustaining their survival, and the mechanism of action of SNS-032 is dependent on the biological context of an individual line.
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Affiliation(s)
- Rong Chen
- Department of Experimental Therapeutics, University of Texas MD Anderson Cancer Center and Graduate School of Biomedical Sciences, University of Texas Houston Health Science Center, Houston, Texas 77030, USA
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244
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Rao R, Nalluri S, Fiskus W, Savoie A, Buckley KM, Ha K, Balusu R, Joshi A, Coothankandaswamy V, Tao J, Sotomayor E, Atadja P, Bhalla KN. Role of CAAT/enhancer binding protein homologous protein in panobinostat-mediated potentiation of bortezomib-induced lethal endoplasmic reticulum stress in mantle cell lymphoma cells. Clin Cancer Res 2010; 16:4742-54. [PMID: 20647473 DOI: 10.1158/1078-0432.ccr-10-0529] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE Bortezomib induces unfolded protein response (UPR) and endoplasmic reticulum stress, as well as exhibits clinical activity in patients with relapsed and refractory mantle cell lymphoma (MCL). Here, we determined the molecular basis of the improved in vitro and in vivo activity of the combination of the pan-histone deacetylase inhibitor panobinostat and bortezomib against human, cultured, and primary MCL cells. EXPERIMENTAL DESIGN Immunoblot analyses, reverse transcription-PCR, and immunofluorescent and electron microscopy were used to determine the effects of panobinostat on bortezomib-induced aggresome formation and endoplasmic reticulum stress in MCL cells. RESULTS Treatment with panobinostat induced heat shock protein 90 acetylation; depleted the levels of heat shock protein 90 client proteins, cyclin-dependent kinase 4, c-RAF, and AKT; and abrogated bortezomib-induced aggresome formation in MCL cells. Panobinostat also induced lethal UPR, associated with induction of CAAT/enhancer binding protein homologous protein (CHOP). Conversely, knockdown of CHOP attenuated panobinostat-induced cell death of MCL cells. Compared with each agent alone, cotreatment with panobinostat increased bortezomib-induced expression of CHOP and NOXA, as well as increased bortezomib-induced UPR and apoptosis of cultured and primary MCL cells. Cotreatment with panobinostat also increased bortezomib-mediated in vivo tumor growth inhibition and improved survival of mice bearing human Z138C MCL cell xenograft. CONCLUSION These findings suggest that increased UPR and induction of CHOP are involved in enhanced anti-MCL activity of the combination of panobinostat and bortezomib.
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Affiliation(s)
- Rekha Rao
- The University of Kansas Cancer Center, Kansas City, 66160, USA
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Sosa Seda IM, Mott JL, Akazawa Y, Barreyro FJ, Bronk SF, Kaufmann SH, Gores GJ. Noxa mediates hepatic stellate cell apoptosis by proteasome inhibition. Hepatol Res 2010; 40:701-10. [PMID: 20557369 PMCID: PMC2922948 DOI: 10.1111/j.1872-034x.2010.00668.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Induction of hepatic stellate cell (HSC) apoptosis is a viable therapeutic strategy to reduce liver fibrogenesis. Although BH3-only proteins of the Bcl-2 family trigger pro-apoptotic pathways, the BH3-only proteins mediating HSC apoptosis have not been well defined. Our aim, using proteasome inhibition as a model to induce HSC apoptosis, was to examine the BH3-only proteins contributing to cell death of this key liver cell subtype. METHODS Apoptosis was induced by treating LX-2 cells, an immortalized human hepatic stellate cell line, and primary rat stellate cells with the proteasome inhibitor MG-132. RESULTS Treatment with proteasome inhibitors increased expression of Noxa both at the mRNA (16-fold) and protein (22-fold) levels indicating that both transcriptional and post-translational mechanisms contributed to the increase in cellular Noxa levels. Knockdown of Noxa by siRNA significantly attenuated cell death, mechanistically implicating Noxa as a key apoptotic mediator of proteasome inhibitor-induced cell death. Given the pivotal role for the anti-apoptotic Bcl-2 protein A1 in activated HSC survival, we determined if Noxa bound to this survival protein. Noxa was shown to physically bind the anti-apoptotic Bcl-2 protein A1 by co-immunoprecipitation. CONCLUSIONS Noxa contributes to proteasome inhibitor-induced apoptosis of stellate cells likely by binding A1. Strategies to therapeutically increase Noxa expression may be useful for inducing HSC apoptosis.
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Affiliation(s)
- Ivette M. Sosa Seda
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905,University of Puerto Rico, School of Medicine, San Juan, Puerto Rico 00926
| | - Justin L. Mott
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Yuko Akazawa
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Fernando J. Barreyro
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Steven F. Bronk
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Scott H. Kaufmann
- Division of Oncology Research, College of Medicine, Mayo Clinic, Rochester, MN 55905
| | - Gregory J. Gores
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
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Ri M, Iida S, Nakashima T, Miyazaki H, Mori F, Ito A, Inagaki A, Kusumoto S, Ishida T, Komatsu H, Shiotsu Y, Ueda R. Bortezomib-resistant myeloma cell lines: a role for mutated PSMB5 in preventing the accumulation of unfolded proteins and fatal ER stress. Leukemia 2010; 24:1506-12. [PMID: 20555361 DOI: 10.1038/leu.2010.137] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bortezomib is an effective agent for treating multiple myeloma (MM). To investigate the underlying mechanisms associated with acquired resistance to this agent, we established two bortezomib-resistant MM cell lines, KMS-11/BTZ and OPM-2/BTZ, the 50% inhibitory concentration values of which were respectively 24.7- and 16.6-fold higher than their parental cell lines. No activation of caspase and BH3-only proteins such as Noxa was noted in bortezomib-resistant cells after exposure to the drug. The accumulation of polyubiquitinated proteins was reduced in bortezomib-resistant cells compared with the parental cells, associated with avoidance of catastrophic ER stress as assessed by downregulation of CHOP expression. These resistant MM cells have a unique point mutation, G322A, in the gene encoding the proteasome beta5 subunit (PSMB5), likely resulting in conformational changes to the bortezomib-binding pocket of this subunit. KMS-11 parental cells transfected to express mutated PSMB5 also showed reduced bortezomib-induced apoptosis compared with those expressing wild-type PSMB5 or the parental cells. Expression of mutated PSMB5 was associated with the prevention of the accumulation of unfolded proteins. Thus, a fraction of MM cells may acquire bortezomib resistance by suppressing apoptotic signals through the inhibition of unfolded protein accumulation and subsequent excessive ER stress by a mutation of the PSMB5 gene.
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Affiliation(s)
- M Ri
- Department of Medical Oncology and Immunology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
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247
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Han YH, Kim SZ, Kim SH, Park WH. Treatment with p38 inhibitor intensifies the death of MG132-treated As4.1 juxtaglomerular cells via the enhancement of GSH depletion. Drug Chem Toxicol 2010; 33:367-76. [PMID: 20545600 DOI: 10.3109/01480540903483458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
MG132, as a proteasome inhibitor, has been shown to induce apoptotic cell death through the formation of reactive oxygen species (ROS). In this study, we investigated the effects of MG132 and/or MAPK inhibitors on As4.1 juxtaglomerular cells in relation to cell growth, cell death, ROS, and glutathione (GSH) levels. MG132 inhibited the growth of As4.1 cells and induced cell death, accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)) and activation of caspase-3 and -8. MG132 increased ROS levels, and GSH depleted cell numbers. The MEK inhibitor slightly reduced cell growth and caspase-3 activity in MG132-treated As4.1 cells and mildly increased MMP (DeltaPsi(m)) loss and O(2)(*-) level. However, it did not increase apoptosis and GSH depletion. The JNK inhibitor did not strongly influence cell growth, cell death, and GSH depletion by MG132, but increased caspase-3 activity, MMP (DeltaPsi(m)) loss, and O(2)(*-) level. Treatment with the p38 inhibitor magnified cell-growth inhibition and apoptosis by MG132. This agent also strongly increased caspase-8 activity, MMP (DeltaPsi(m)) loss, O(2)(*-) level, and GSH depletion. Conclusively, the p38 inhibitor strongly intensified cell death in MG132-treated As4.1 cells. The changes of GSH content by MG132 and/or MAPK inhibitors were closely related to the death of As4.1 cells.
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Affiliation(s)
- Yong Hwan Han
- Department of Physiology, Medical School, Centers for Healthcare Technology Development, Institute for Medical Sciences, Chonbuk National University, JeonJu, Republic of Korea
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248
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Han YH, Park WH. Treatment with p38 inhibitor partially prevents Calu-6 lung cancer cell death by a proteasome inhibitor, MG132. ACTA ACUST UNITED AC 2010; 199:81-8. [PMID: 20471510 DOI: 10.1016/j.cancergencyto.2010.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 12/24/2009] [Accepted: 02/01/2010] [Indexed: 11/18/2022]
Abstract
MG132 (carbobenzoxy-Leu-Leu-leucinal) as a proteasome inhibitor has been shown to induce apoptotic cell death through formation of reactive oxygen species (ROS). In this study, we investigated the effects of MEK (mitogen-activated protein [MAP] kinase or extracellular signal-regulated kinase [ERK] kinase) or p38 inhibitor on MG132-treated Calu-6 lung cancer cells in relation to cell growth, cell death, ROS, and glutathione (GSH) levels. Treatment with 10 mumol/L MG132 inhibited the growth of Calu-6 cells at 24 hours. MG132 induced apoptosis in Calu-6 cells, which was accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)). ROS were increased in MG132-treated Calu-6 cells. MG132 also induced GSH depletion in Calu-6 cells. Treatment with MEK inhibitor did not significantly affect cell growth, cell death, ROS, and GSH levels in MG132-treated Calu-6 cells. Furthermore, MG132 increased the phosphorylation of p38 in Calu-6 cells at 1 and 24 hours. Treatment with p38 inhibitor significantly prevented cell growth inhibition, MMP (DeltaPsi(m)) loss and apoptosis in MG132-treated Calu-6 cells. This inhibitor increased ROS level and decreased GSH depletion in these cells. In conclusion, p38 inhibitor partially prevented Calu-6 cell death by MG132, which might be affected by GSH level changes.
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Affiliation(s)
- Yong Hwan Han
- Department of Physiology, Medical School, Institute for Medical Sciences, Chonbuk National University, Jeon Ju, 561-180, Republic of Korea
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249
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Desai S, Maurin M, Smith MA, Bolick SC, Dessureault S, Tao J, Sotomayor E, Wright KL. PRDM1 is required for mantle cell lymphoma response to bortezomib. Mol Cancer Res 2010; 8:907-18. [PMID: 20530581 PMCID: PMC2891394 DOI: 10.1158/1541-7786.mcr-10-0131] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mantle cell lymphoma (MCL) is an aggressive form of B-cell lymphoma with a poor disease-free survival rate. The proteasome inhibitor bortezomib is approved for the treatment of relapsed and refractory MCL and has efficacy in about 30% of patients. However, the precise mechanism of action of bortezomib is not well understood. This report establishes a requirement for the transcription repressor PR domain zinc finger protein 1 (PRDM1, Blimp1) in the response to bortezomib. Bortezomib rapidly induces transcription of PRDM1 as part of the apoptotic response in both cell lines and primary MCL tumor cells. Knockdown of PRDM1 blocks activation of NOXA and inhibits apoptosis, whereas ectopic expression of PRDM1 alone leads to apoptosis in MCL. Two novel direct targets of PRDM1 were identified in MCL cells: MKI67 (Ki67) and proliferating cell nuclear antigen (PCNA). Both MKI67 and PCNA are required for proliferation and survival. Chromatin immunoprecipitation and knockdown studies reveal that specific repression of MKI67 and PCNA is mediated by PRDM1 in response to bortezomib. Furthermore, promoter studies and mutation/deletion analysis show that PRDM1 functions through specific sites in the PCNA proximal promoter and an MKI67 distal upstream repression domain. Together, these findings establish PRDM1 as a key mediator of bortezomib activity in MCL.
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Affiliation(s)
- Shruti Desai
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612
- Cancer Biology PhD Program, University of South Florida., Tampa, FL 33612
| | - Michelle Maurin
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612
| | - Matthew A. Smith
- Department of Molecular Medicine, University of South Florida., Tampa, FL 33612
| | - Sophia C.E. Bolick
- Department of Molecular Medicine, University of South Florida., Tampa, FL 33612
| | - Sophie Dessureault
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612
- Department of Oncologic Sciences, University of South Florida., Tampa, FL 33612
| | - Jianguo Tao
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612
- Department of Oncologic Sciences, University of South Florida., Tampa, FL 33612
| | - Eduardo Sotomayor
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612
- Department of Oncologic Sciences, University of South Florida., Tampa, FL 33612
| | - Kenneth L. Wright
- H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612
- Cancer Biology PhD Program, University of South Florida., Tampa, FL 33612
- Department of Oncologic Sciences, University of South Florida., Tampa, FL 33612
- Department of Molecular Medicine, University of South Florida., Tampa, FL 33612
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250
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Han YH, Park WH. Proteasome inhibitor MG132 reduces growth of As4.1 juxtaglomerular cells via caspase-independent apoptosis. Arch Toxicol 2010; 84:689-98. [DOI: 10.1007/s00204-010-0550-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 04/19/2010] [Indexed: 10/19/2022]
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