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Liu C, Sun S, Mao J. Water-soluble Yb 3+, Er 3+ codoped NaYF 4 nanoparticles induced SGC-7901 cell apoptosis through mitochondrial dysfunction and ROS-mediated ER stress. Hum Exp Toxicol 2023; 42:9603271231188493. [PMID: 37419518 DOI: 10.1177/09603271231188493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
BACKGROUND Nanoparticles are potential luminescent probes; among them, upconversion nanoparticles (UCNP) are currently being developed as fluorescent probes for biomedical applications. However, the molecular mechanisms of UCNP in human gastric cell lines remain poorly understood. Here, we aimed to examine UCNP cytotoxicity to SGC-7901 cells and explore its underlying mechanisms. METHODS The effects of 50-400 μg/mL UCNP on human gastric adenocarcinoma (SGC-7901) cells were investigated. Flow cytometry was used to evaluate reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), intracellular Ca2+ levels, and apoptosis. Activated caspase-3 and nine activities were measured; meanwhile, cytochrome C (Cyt C) in the cytosol and B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), protein kinase B (Akt), phosphorylated-Akt (p-Akt), 78 kDa glucose-regulated protein (GRP78), 94 kDa glucose-regulated protein (GRP94), calpain-1, and calpain-2 protein levels were also detected. RESULTS UCNP inhibited the viability of SGC-7901 cells in a concentration- and time-dependent manner and increased the proportion of cell apoptosis. Exposure to UCNP enhanced the ratio of Bax/Bcl-2, elevated the level of ROS, decreased ΔΨm, increased intracellular Ca2+ and Cyt C protein levels, decreased the levels of phosphorylated Akt, increased the activity of caspase-3 and caspase-9, and upregulated the protein expression of GRP-78, GRP-94, calpain-1 and calpain-2 in SGC-7901 cells. CONCLUSION UCNP induced SGC-7901 cell apoptosis by promoting mitochondrial dysfunction and ROS-mediated endoplasmic reticulum (ER) stress, initiating the caspase-9/caspase-3 cascade.
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Affiliation(s)
- Chen Liu
- Department of Gastroenterology, First Affiliated Hospital of Dalian Medical University, Dalian, P.R. China
| | - Shaoqiang Sun
- Department of Gastroenterology, First Affiliated Hospital of Dalian Medical University, Dalian, P.R. China
| | - Jingwei Mao
- Department of Gastroenterology, First Affiliated Hospital of Dalian Medical University, Dalian, P.R. China
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2
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Djuzenova CS, Fischer T, Katzer A, Sisario D, Korsa T, Steussloff G, Sukhorukov VL, Flentje M. Opposite effects of the triple target (DNA-PK/PI3K/mTOR) inhibitor PI-103 on the radiation sensitivity of glioblastoma cell lines proficient and deficient in DNA-PKcs. BMC Cancer 2021; 21:1201. [PMID: 34763650 PMCID: PMC8582108 DOI: 10.1186/s12885-021-08930-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 10/28/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Radiotherapy is routinely used to combat glioblastoma (GBM). However, the treatment efficacy is often limited by the radioresistance of GBM cells. METHODS Two GBM lines MO59K and MO59J, differing in intrinsic radiosensitivity and mutational status of DNA-PK and ATM, were analyzed regarding their response to DNA-PK/PI3K/mTOR inhibition by PI-103 in combination with radiation. To this end we assessed colony-forming ability, induction and repair of DNA damage by γH2AX and 53BP1, expression of marker proteins, including those belonging to NHEJ and HR repair pathways, degree of apoptosis, autophagy, and cell cycle alterations. RESULTS We found that PI-103 radiosensitized MO59K cells but, surprisingly, it induced radiation resistance in MO59J cells. Treatment of MO59K cells with PI-103 lead to protraction of the DNA damage repair as compared to drug-free irradiated cells. In PI-103-treated and irradiated MO59J cells the foci numbers of both proteins was higher than in the drug-free samples, but a large portion of DNA damage was quickly repaired. Another cell line-specific difference includes diminished expression of p53 in MO59J cells, which was further reduced by PI-103. Additionally, PI-103-treated MO59K cells exhibited an increased expression of the apoptosis marker cleaved PARP and increased subG1 fraction. Moreover, irradiation induced a strong G2 arrest in MO59J cells (~ 80% vs. ~ 50% in MO59K), which was, however, partially reduced in the presence of PI-103. In contrast, treatment with PI-103 increased the G2 fraction in irradiated MO59K cells. CONCLUSIONS The triple-target inhibitor PI-103 exerted radiosensitization on MO59K cells, but, unexpectedly, caused radioresistance in the MO59J line, lacking DNA-PK. The difference is most likely due to low expression of the DNA-PK substrate p53 in MO59J cells, which was further reduced by PI-103. This led to less apoptosis as compared to drug-free MO59J cells and enhanced survival via partially abolished cell-cycle arrest. The findings suggest that the lack of DNA-PK-dependent NHEJ in MO59J line might be compensated by DNA-PK independent DSB repair via a yet unknown mechanism.
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Affiliation(s)
- Cholpon S Djuzenova
- Department of Radiation Oncology, University Hospital of Würzburg, Josef-Schneider-Strasse 11, 97080, Würzburg, Germany.
| | - Thomas Fischer
- Department of Radiation Oncology, University Hospital of Würzburg, Josef-Schneider-Strasse 11, 97080, Würzburg, Germany
| | - Astrid Katzer
- Department of Radiation Oncology, University Hospital of Würzburg, Josef-Schneider-Strasse 11, 97080, Würzburg, Germany
| | - Dmitri Sisario
- Department of Biotechnology and Biophysics, University of Würzburg, Würzburg, Germany
| | - Tessa Korsa
- Department of Biotechnology and Biophysics, University of Würzburg, Würzburg, Germany
| | - Gudrun Steussloff
- Department of Radiation Oncology, University Hospital of Würzburg, Josef-Schneider-Strasse 11, 97080, Würzburg, Germany
| | - Vladimir L Sukhorukov
- Department of Biotechnology and Biophysics, University of Würzburg, Würzburg, Germany
| | - Michael Flentje
- Department of Radiation Oncology, University Hospital of Würzburg, Josef-Schneider-Strasse 11, 97080, Würzburg, Germany
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Cingöz A, Ozyerli-Goknar E, Morova T, Seker-Polat F, Esai Selvan M, Gümüş ZH, Bhere D, Shah K, Solaroglu I, Bagci-Onder T. Generation of TRAIL-resistant cell line models reveals distinct adaptive mechanisms for acquired resistance and re-sensitization. Oncogene 2021; 40:3201-3216. [PMID: 33767436 DOI: 10.1038/s41388-021-01697-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 01/21/2021] [Accepted: 02/04/2021] [Indexed: 02/01/2023]
Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces tumor cell-specific apoptosis, making it a prime therapeutic candidate. However, many tumor cells are either innately TRAIL-resistant, or they acquire resistance with adaptive mechanisms that remain poorly understood. In this study, we generated acquired TRAIL resistance models using multiple glioblastoma (GBM) cell lines to assess the molecular alterations in the TRAIL-resistant state. We selected TRAIL-resistant cells through chronic and long-term TRAIL exposure and noted that they showed persistent resistance both in vitro and in vivo. Among known TRAIL-sensitizers, proteosome inhibitor Bortezomib, but not HDAC inhibitor MS-275, was effective in overcoming resistance in all cell models. This was partly achieved through upregulating death receptors and pro-apoptotic proteins, and downregulating major anti-apoptotic members, Bcl-2 and Bcl-xL. We showed that CRISPR/Cas9 mediated silencing of DR5 could block Bortezomib-mediated re-sensitization, demonstrating its critical role. While overexpression of Bcl-2 or Bcl-xL was sufficient to confer resistance to TRAIL-sensitive cells, it failed to override Bortezomib-mediated re-sensitization. With RNA sequencing in multiple paired TRAIL-sensitive and TRAIL-resistant cells, we identified major alterations in inflammatory signaling, particularly in the NF-κB pathway. Inhibiting NF-κB substantially sensitized the most resistant cells to TRAIL, however, the sensitization effect was not as great as what was observed with Bortezomib. Together, our findings provide new models of acquired TRAIL resistance, which will provide essential tools to gain further insight into the heterogeneous therapy responses within GBM tumors. Additionally, these findings emphasize the critical importance of combining proteasome inhibitors and pro-apoptotic ligands to overcome acquired resistance.
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Affiliation(s)
- Ahmet Cingöz
- Brain Cancer Research and Therapy Laboratory, Koç University Research Center for Translational Medicine, Istanbul, 34450, Turkey
- Koç University School of Medicine, Istanbul, 34450, Turkey
| | - Ezgi Ozyerli-Goknar
- Brain Cancer Research and Therapy Laboratory, Koç University Research Center for Translational Medicine, Istanbul, 34450, Turkey
- Koç University School of Medicine, Istanbul, 34450, Turkey
| | - Tunc Morova
- Koç University School of Medicine, Istanbul, 34450, Turkey
| | - Fidan Seker-Polat
- Brain Cancer Research and Therapy Laboratory, Koç University Research Center for Translational Medicine, Istanbul, 34450, Turkey
- Koç University School of Medicine, Istanbul, 34450, Turkey
| | - Myvizhi Esai Selvan
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Zeynep Hülya Gümüş
- Koç University School of Medicine, Istanbul, 34450, Turkey
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Deepak Bhere
- Center for Stem Cell Therapeutics and Imaging, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Khalid Shah
- Center for Stem Cell Therapeutics and Imaging, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Ihsan Solaroglu
- Koç University School of Medicine, Istanbul, 34450, Turkey
- Department of Neurosurgery, Koç University School of Medicine, Istanbul, 34010, Turkey
| | - Tugba Bagci-Onder
- Brain Cancer Research and Therapy Laboratory, Koç University Research Center for Translational Medicine, Istanbul, 34450, Turkey.
- Koç University School of Medicine, Istanbul, 34450, Turkey.
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Chowdhury FA, Hossain MK, Mostofa AGM, Akbor MM, Bin Sayeed MS. Therapeutic Potential of Thymoquinone in Glioblastoma Treatment: Targeting Major Gliomagenesis Signaling Pathways. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4010629. [PMID: 29651429 PMCID: PMC5831880 DOI: 10.1155/2018/4010629] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 12/27/2017] [Indexed: 02/06/2023]
Abstract
Glioblastoma multiforme (GBM) is one of the most devastating brain tumors with median survival of one year and presents unique challenges to therapy because of its aggressive behavior. Current treatment strategy involves surgery, radiotherapy, immunotherapy, and adjuvant chemotherapy even though optimal management requires a multidisciplinary approach and knowledge of potential complications from both the disease and its treatment. Thymoquinone (TQ), the main bioactive component of Nigella sativa L., has exhibited anticancer effects in numerous preclinical studies. Due to its multitargeting nature, TQ interferes in a wide range of tumorigenic processes and counteract carcinogenesis, malignant growth, invasion, migration, and angiogenesis. TQ can specifically sensitize tumor cells towards conventional cancer treatments and minimize therapy-associated toxic effects in normal cells. Its potential to enter brain via nasal pathway due to volatile nature of TQ adds another advantage in overcoming blood-brain barrier. In this review, we summarized the potential role of TQ in different signaling pathways in GBM that have undergone treatment with standard therapeutic modalities or with TQ. Altogether, we suggest further comprehensive evaluation of TQ in preclinical and clinical level to delineate its implied utility as novel therapeutics to combat the challenges for the treatment of GBM.
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Affiliation(s)
- Fabliha Ahmed Chowdhury
- Department of Clinical Pharmacy and Pharmacology, University of Dhaka, Dhaka 1000, Bangladesh
| | - Md Kamal Hossain
- Department of Pharmaceutical Chemistry, University of Dhaka, Dhaka 1000, Bangladesh
| | - A. G. M. Mostofa
- Department of Clinical Pharmacy and Pharmacology, University of Dhaka, Dhaka 1000, Bangladesh
| | - Maruf Mohammad Akbor
- Department of Clinical Pharmacy and Pharmacology, University of Dhaka, Dhaka 1000, Bangladesh
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Abstract
Radiation therapy methods have evolved remarkably in recent years which have resulted in more effective local tumor control with negligible toxicity of surrounding normal tissues. However, local recurrence and distant metastasis often occur following radiation therapy mostly due to the development of radioresistance through the deregulation of the cell cycle, apoptosis, and inhibition of DNA damage repair mechanisms. Over the last decade, extensive progress in radiotherapy and gene therapy combinatorial approaches has been achieved to overcome resistance of tumor cells to radiation. In this review, we summarize the results from experimental cancer therapy studies on the combination of radiation therapy and gene therapy.
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Hah YS, Noh HS, Ha JH, Ahn JS, Hahm JR, Cho HY, Kim DR. Cathepsin D inhibits oxidative stress-induced cell death via activation of autophagy in cancer cells. Cancer Lett 2012; 323:208-14. [PMID: 22542809 DOI: 10.1016/j.canlet.2012.04.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 04/17/2012] [Accepted: 04/17/2012] [Indexed: 12/19/2022]
Abstract
Cathepsin D (CatD), a lysosomal aspartic protease, plays an essential role in tumor progression and apoptosis. However, the function of CatD in cell death is not yet fully understood. In this study, we identified CatD as one of up-regulated proteins in human malignant glioblastoma M059J cells that lack the catalytic subunit of DNA-PK compared with its isogenic M059K cells with normal DNA-PK activity. M059J cells were relatively more resistant to genotoxic stress than M059K cells. Overexpression of wild-type CatD but not catalytically inactive mutant CatD (D295N) inhibited H(2)O(2)-induced cell death in HeLa cells. Furthermore, knockdown of CatD expression abolished anti-apoptotic effect by CatD in the presence of H(2)O(2). Interestingly, high expression of CatD in HeLa cells significantly activated autophagy: increase of acidic autophagic vacuoles, LC3-II formation, and GFP-LC3 puncta. These results suggest that CatD can function as an anti-apoptotic mediator by inducing autophagy under cellular stress. In conclusion, inhibition of autophagy could be a novel strategy for the adjuvant chemotherapy of CatD-expressing cancers.
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Affiliation(s)
- Young-Sool Hah
- Clinical Research Institute, Gyeongsang National University Hospital, Jinju, Republic of Korea
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7
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Dix MM, Simon GM, Wang C, Okerberg E, Patricelli MP, Cravatt BF. Functional interplay between caspase cleavage and phosphorylation sculpts the apoptotic proteome. Cell 2012; 150:426-40. [PMID: 22817901 DOI: 10.1016/j.cell.2012.05.040] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 03/26/2012] [Accepted: 05/16/2012] [Indexed: 12/14/2022]
Abstract
Caspase proteases are principal mediators of apoptosis, where they cleave hundreds of proteins. Phosphorylation also plays an important role in apoptosis, although the extent to which proteolytic and phosphorylation pathways crosstalk during programmed cell death remains poorly understood. Using a quantitative proteomic platform that integrates phosphorylation sites into the topographical maps of proteins, we identify a cohort of over 500 apoptosis-specific phosphorylation events and show that they are enriched on cleaved proteins and clustered around sites of caspase proteolysis. We find that caspase cleavage can expose new sites for phosphorylation, and, conversely, that phosphorylation at the +3 position of cleavage sites can directly promote substrate proteolysis by caspase-8. This study provides a global portrait of the apoptotic phosphoproteome, revealing heretofore unrecognized forms of functional crosstalk between phosphorylation and caspase proteolytic pathways that lead to enhanced rates of protein cleavage and the unveiling of new sites for phosphorylation.
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Affiliation(s)
- Melissa M Dix
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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8
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Lim HK, Asharani PV, Hande MP. Enhanced genotoxicity of silver nanoparticles in DNA repair deficient Mammalian cells. Front Genet 2012; 3:104. [PMID: 22707954 PMCID: PMC3374476 DOI: 10.3389/fgene.2012.00104] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 05/21/2012] [Indexed: 11/25/2022] Open
Abstract
Silver nanoparticles (Ag-np) have been used in medicine and commercially due to their anti-microbial properties. Therapeutic potentials of these nanoparticles are being explored extensively despite the lack of information on their mechanism of action at molecular and cellular level. Here, we have investigated the DNA damage response and repair following Ag-np treatment in mammalian cells. Studies have shown that Ag-np exerts genotoxicity through double-strand breaks (DSBs). DNA-PKcs, the catalytic subunit of DNA dependent protein kinase, is an important caretaker of the genome which is known to be the main player mediating Non-homologous End-Joining (NHEJ) repair pathway. We hypothesize that DNA-PKcs is responsible for the repair of Ag-np induced DNA damage. In vitro studies have been carried out to investigate both cytotoxicity and genotoxicity induced by Ag-np in normal human cells, DNA-PKcs proficient, and deficient mammalian cells. Chemical inhibition of DNA-PKcs activity with NU7026, an ATP-competitive inhibitor of DNA-PKcs, has been performed to further validate the role of DNA-PKcs in this model. Our results suggest that Ag-np induced more prominent dose-dependent decrease in cell viability in DNA-PKcs deficient or inhibited cells. The deficiency or inhibition of DNA-PKcs renders the cells with higher susceptibility to DNA damage and genome instability which in turn contributed to greater cell cycle arrest/cell death. These findings support the fact that DNA-PKcs is involved in the repair of Ag-np induced genotoxicity and NHEJ repair pathway and DNA-PKcs particularly is activated to safeguard the genome upon Ag-np exposure.
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Affiliation(s)
- Hui Kheng Lim
- Genome Stability Laboratory, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore Singapore
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Poon WS. Great hospitals of Asia: neurosurgery at Prince of Wales Hospital. World Neurosurg 2011; 75:383-6. [PMID: 21600469 DOI: 10.1016/j.wneu.2011.02.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 02/08/2011] [Indexed: 10/18/2022]
Abstract
Prince of Wales Hospital, a 1400-bed regional referral center, was established in 1984 as the primary teaching hospital of the second medical school in Hong Kong at the Chinese University of Hong Kong. The Academic Division of Neurosurgery was given an autonomous status, the support of 40 acute beds, and a well-equipped and well-staffed intensive care unit (ICU), in developing neurosurgery as a distinct surgical specialty. Over this short 26-year history, we have gone through the difficult time of one-man-band neurosurgery, excelled in emergency neurosurgery, and evolved to an era of organized neurosurgical practice, where clinical services, teaching of undergraduate and postgraduate students, and clinical and translational research have been brought up to international standards.
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Affiliation(s)
- Wai S Poon
- Division of Neurosurgery, Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong.
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10
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Gurung RL, Lim SN, Khaw AK, Soon JFF, Shenoy K, Mohamed Ali S, Jayapal M, Sethu S, Baskar R, Hande MP. Thymoquinone induces telomere shortening, DNA damage and apoptosis in human glioblastoma cells. PLoS One 2010; 5:e12124. [PMID: 20711342 PMCID: PMC2920825 DOI: 10.1371/journal.pone.0012124] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 06/22/2010] [Indexed: 12/15/2022] Open
Abstract
Background A major concern of cancer chemotherapy is the side effects caused by the non-specific targeting of both normal and cancerous cells by therapeutic drugs. Much emphasis has been placed on discovering new compounds that target tumour cells more efficiently and selectively with minimal toxic effects on normal cells. Methodology/Principal Findings The cytotoxic effect of thymoquinone, a component derived from the plant Nigella sativa, was tested on human glioblastoma and normal cells. Our findings demonstrated that glioblastoma cells were more sensitive to thymoquinone-induced antiproliferative effects. Thymoquinone induced DNA damage, cell cycle arrest and apoptosis in the glioblastoma cells. It was also observed that thymoquinone facilitated telomere attrition by inhibiting the activity of telomerase. In addition to these, we investigated the role of DNA-PKcs on thymoquinone mediated changes in telomere length. Telomeres in glioblastoma cells with DNA-PKcs were more sensitive to thymoquinone mediated effects as compared to those cells deficient in DNA-PKcs. Conclusions/Significance Our results indicate that thymoquinone induces DNA damage, telomere attrition by inhibiting telomerase and cell death in glioblastoma cells. Telomere shortening was found to be dependent on the status of DNA-PKcs. Collectively, these data suggest that thymoquinone could be useful as a potential chemotherapeutic agent in the management for brain tumours.
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Affiliation(s)
- Resham Lal Gurung
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Shi Ni Lim
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Aik Kia Khaw
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jasmine Fen Fen Soon
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Kirthan Shenoy
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Safiyya Mohamed Ali
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Manikandan Jayapal
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Swaminathan Sethu
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Rajamanickam Baskar
- Division of Cellular and Molecular Research, Department of Radiation Oncology, National Cancer Centre, Singapore, Singapore
| | - M. Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- * E-mail:
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Liu J, Naegele JR, Lin SL. The DNA-PK catalytic subunit regulates Bax-mediated excitotoxic cell death by Ku70 phosphorylation. Brain Res 2009; 1296:164-75. [PMID: 19664609 DOI: 10.1016/j.brainres.2009.07.101] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 07/27/2009] [Accepted: 07/30/2009] [Indexed: 10/20/2022]
Abstract
DNA repair deficiency results in neurodegenerative disease and increased susceptibility to excitotoxic cell death, suggesting a critical but undefined role for DNA damage in neurodegeneration. We compared DNA damage, Ku70-Bax interaction, and Bax-dependent excitotoxic cell death in kainic acid-treated primary cortical neurons derived from both wild-type mice and mice deficient in the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) encoded by the Prkdc gene. In both wild-type and Prkdc(-/-) neurons, kainic acid treatment resulted in rapid induction of DNA damage (53BP1 foci formation) followed by nuclear pyknosis. Bax deficiency, by either Bax shRNA-mediated knockdown or gene deletion, protected wild-type and heterozygous but not Prkdc(-/-) neurons from kainate-induced excitotoxicity. Cotransfection of DNA-PKcs with Bax shRNA restored Bax shRNA-mediated neuroprotection in Prkdc(-/-) neurons, suggesting that DNA-PKcs is required for kainate-induced activation of the pro-apoptotic Bax pathway. Immunoprecipitation studies revealed that the DNA-PKcs-nonphosphorylatable Ku70 (S6A/S51A) bound 3- to 4-fold greater Bax than wild-type Ku70, suggesting that DNA-PKcs-mediated Ku70 phosphorylation causes release of Bax from Ku70. In support of this, kainic acid induced translocation of a Bax-EGFP fusion protein to the mitochondria in the presence of a cotransfected wild-type, but not mutant Ku70 (S6A/S51A) gene when examined at 4 and 8 h following kainate addition. We conclude that DNA-PKcs links DNA damage to Bax-dependent excitotoxic cell death, by phosphorylating Ku70 on serines 6 and/or 51, to initiate Bax translocation to the mitochondria and directly activate a pro-apoptotic Bax-dependent death cascade.
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Affiliation(s)
- Jia Liu
- Program in Neuroscience and Behavior, Department of Biology, Wesleyan University, Middletown, CT 06459-0170, USA
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Lovastatin sensitized human glioblastoma cells to TRAIL-induced apoptosis. J Neurooncol 2007; 86:273-83. [PMID: 17928957 PMCID: PMC2174520 DOI: 10.1007/s11060-007-9475-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2007] [Accepted: 09/18/2007] [Indexed: 11/23/2022]
Abstract
Synergy study with chemotherapeutic agents is a common in vitro strategy in the search for effective cancer therapy. For non-chemotherapeutic agents, efficacious synergistic effects are uncommon. Here, we have examined two non-chemotherapeutic agents for synergistic effects: lovastatin and Tumor Necrosis Factor (TNF)-related apoptosis-inducing ligand (TRAIL) for synergistic effects; on three human malignant glioblastoma cell lines, M059K, M59J, and A172. Cells treated with lovastatin plus TRAIL for 48 h showed 50% apoptotic cell death, whereas TRAIL alone (1,000 ng/ml) did not, suggesting that lovastatin sensitized the glioblastoma cells to TRAIL attack. Cell cycle analysis indicated that lovastatin increased G0–G1 arrest in these cells. Annexin V study demonstrated that apoptosis was the predominant mode of cell death. We conclude that the combination of lovastatin and TRAIL enhances apoptosis synergistically. Moreover, lovastatin sensitized glioblastoma cells to TRAIL, suggesting a new strategy to treat glioblastoma.
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Ju DS, Kim MJ, Bae JH, Song HS, Chung BS, Lee MK, Kang CD, Lee HS, Kim DW, Kim SH. Camptothecin acts synergistically with imatinib and overcomes imatinib resistance through Bcr-Abl independence in human K562 cells. Cancer Lett 2007; 252:75-85. [PMID: 17223257 DOI: 10.1016/j.canlet.2006.12.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 12/08/2006] [Accepted: 12/12/2006] [Indexed: 11/28/2022]
Abstract
In this study, we have tried to find new targets and effective drugs for imatinib-resistant chronic myelogenous leukemia (CML) cells displaying loss of Bcr-Abl kinase target dependence. The imatinib-resistant K562/R1, -R2 and -R3 cells showed profound declines of Bcr-Abl level and concurrently exhibited up-regulation of Bcl-2 and Ku70/80, and down-regulation of Bax, DNA-PKcs and BRCA1, suggesting that loss of Bcr-Abl after exposure to imatinib might be accompanied by other cell survival mechanism. K562/R3 cells were more sensitive to camptothecin (CPT)- and radiation-induced apoptosis than K562 cells, indicating hypersensitivity of imatinib-resistant cells to DNA damaging agents. Moreover, when K562 cells were treated with the combination of imatinib with CPT, the level of Bax and the cleavage of PARP-1 and DNA-PK were significantly increased in comparison with the effects of each drug. Therefore, our study suggests that CPT can be used to treat CML with loss of Bcr-Abl expression.
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Affiliation(s)
- Dong-Sik Ju
- Department of Biochemistry, Pusan National University School of Medicine, Busan 602-739, South Korea
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Acker T, Diez-Juan A, Aragones J, Tjwa M, Brusselmans K, Moons L, Fukumura D, Moreno-Murciano MP, Herbert JM, Burger A, Riedel J, Elvert G, Flamme I, Maxwell PH, Collen D, Dewerchin M, Jain RK, Plate KH, Carmeliet P. Genetic evidence for a tumor suppressor role of HIF-2alpha. Cancer Cell 2005; 8:131-41. [PMID: 16098466 DOI: 10.1016/j.ccr.2005.07.003] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2003] [Revised: 01/14/2005] [Accepted: 07/19/2005] [Indexed: 10/25/2022]
Abstract
The hypoxia-inducible transcription factors HIF-1alpha and HIF-2alpha are activated in hypoxic tumor regions. However, their role in tumorigenesis remains controversial, as tumor growth promoter and suppressor activities have been ascribed to HIF-1alpha, while the role of HIF-2alpha remains largely unknown. Here, we show that overexpression of HIF-2alpha in rat glioma tumors enhances angiogenesis but reduces growth of these tumors, in part by increasing tumor cell apoptosis. Moreover, siRNA knockdown of HIF-2alpha reduced apoptosis in hypoxic human malignant glioblastoma cells. Furthermore, inhibition of HIF by overexpression of a dominant-negative HIF transgene in glioma cells or HIF-2alpha deficiency in teratomas reduced vascularization but accelerated growth of these tumor types. These findings urge careful consideration of using HIF inhibitors as cancer therapeutic strategies.
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Affiliation(s)
- Till Acker
- Edinger Institute, Neuropathology, Johann Wolfgang Goethe University, 60528 Frankfurt, Germany.
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