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García-López D, Zaragoza-Ojeda M, Eguía-Aguilar P, Arenas-Huertero F. Endoplasmic Reticulum Stress in Gliomas: Exploiting a Dual-Effect Dysfunction through Chemical Pharmaceutical Compounds and Natural Derivatives for Therapeutical Uses. Int J Mol Sci 2024; 25:4078. [PMID: 38612890 PMCID: PMC11012637 DOI: 10.3390/ijms25074078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 04/14/2024] Open
Abstract
The endoplasmic reticulum maintains proteostasis, which can be disrupted by oxidative stress, nutrient deprivation, hypoxia, lack of ATP, and toxicity caused by xenobiotic compounds, all of which can result in the accumulation of misfolded proteins. These stressors activate the unfolded protein response (UPR), which aims to restore proteostasis and avoid cell death. However, endoplasmic response-associated degradation (ERAD) is sometimes triggered to degrade the misfolded and unassembled proteins instead. If stress persists, cells activate three sensors: PERK, IRE-1, and ATF6. Glioma cells can use these sensors to remain unresponsive to chemotherapeutic treatments. In such cases, the activation of ATF4 via PERK and some proteins via IRE-1 can promote several types of cell death. The search for new antitumor compounds that can successfully and directly induce an endoplasmic reticulum stress response ranges from ligands to oxygen-dependent metabolic pathways in the cell capable of activating cell death pathways. Herein, we discuss the importance of the ER stress mechanism in glioma and likely therapeutic targets within the UPR pathway, as well as chemicals, pharmaceutical compounds, and natural derivatives of potential use against gliomas.
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Affiliation(s)
- Daniel García-López
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico; (D.G.-L.); (M.Z.-O.); (P.E.-A.)
- Facultad de Ciencia y Tecnología, Universidad Simón Bolívar, Mexico City 03920, Mexico
| | - Montserrat Zaragoza-Ojeda
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico; (D.G.-L.); (M.Z.-O.); (P.E.-A.)
| | - Pilar Eguía-Aguilar
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico; (D.G.-L.); (M.Z.-O.); (P.E.-A.)
- Departamento de Patología Clínica y Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico
| | - Francisco Arenas-Huertero
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico; (D.G.-L.); (M.Z.-O.); (P.E.-A.)
- Centro de Investigación en Biomedicina y Bioseguridad, Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico
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Roy A, Chakraborty AR, DePamphilis ML. PIKFYVE inhibitors trigger interleukin-24-dependent cell death of autophagy-dependent melanoma. Mol Oncol 2024; 18:988-1011. [PMID: 38414326 PMCID: PMC10994231 DOI: 10.1002/1878-0261.13607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/16/2024] [Accepted: 02/02/2024] [Indexed: 02/29/2024] Open
Abstract
Inhibitors specifically targeting the 1-phosphatidylinositol 3-phosphate 5-kinase (PIKFYVE) disrupt lysosome homeostasis, thereby selectively terminating autophagy-dependent human cancer cells in vivo as well as in vitro without harming the viability of nonmalignant cells. To elucidate the mechanism by which PIKFYVE inhibition induces cell death, autophagy-dependent melanoma cells were compared with normal foreskin fibroblasts. RNA sequence profiling suggested that PIKFYVE inhibitors upregulated an endoplasmic reticulum (ER) stress response involving interleukin-24 (IL24; also known as MDA7) selectively in melanoma cells. Subsequent biochemical and genetic analyses confirmed these results and extended them to tumor xenografts in which tumor formation and expansion were inhibited. IL24 expression was upregulated by the DDIT3/CHOP/CEBPz transcription factor, a component of the PERK-dependent ER-stress response. Ectopic expression of IL24-induced cell death in melanoma cells, but not in foreskin fibroblasts, whereas ablation of the IL24 gene in melanoma cells prevented death. IL24 upregulation was triggered specifically by PIKFYVE inhibition. Thus, unlike thapsigargin and tunicamycin, which induce ER-stress indiscriminately, PIKFYVE inhibitors selectively terminated PIKFYVE-sensitive melanoma by inducing IL24-dependent ER-stress. Moreover, induction of cell death by a PIKFYVE inhibitor together with ectopic expression of IL24 protein was cumulative, thereby confirming the therapeutic potential of PIKFYVE inhibitors in the treatment of melanoma.
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Affiliation(s)
- Ajit Roy
- National Institute of Child Health & Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Arup R. Chakraborty
- National Institute of Child Health & Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Melvin L. DePamphilis
- National Institute of Child Health & Human DevelopmentNational Institutes of HealthBethesdaMDUSA
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3
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Lai H, Liu Y, Wu J, Cai J, Jie H, Xu Y, Deng S. Targeting cancer-related inflammation with non-steroidal anti-inflammatory drugs: Perspectives in pharmacogenomics. Front Pharmacol 2022; 13:1078766. [PMID: 36545311 PMCID: PMC9760816 DOI: 10.3389/fphar.2022.1078766] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/25/2022] [Indexed: 12/11/2022] Open
Abstract
Inflammatory processes are essential for innate immunity and contribute to carcinogenesis in various malignancies, such as colorectal cancer, esophageal cancer and lung cancer. Pharmacotherapies targeting inflammation have the potential to reduce the risk of carcinogenesis and improve therapeutic efficacy of existing anti-cancer treatment. Non-steroidal anti-inflammatory drugs (NSAIDs), comprising a variety of structurally different chemicals that can inhibit cyclooxygenase (COX) enzymes and other COX-independent pathways, are originally used to treat inflammatory diseases, but their preventive and therapeutic potential for cancers have also attracted researchers' attention. Pharmacogenomic variability, including distinct genetic characteristics among different patients, can significantly affect pharmacokinetics and effectiveness of NSAIDs, which might determine the preventive or therapeutic success for cancer patients. Hence, a more comprehensive understanding in pharmacogenomic characteristics of NSAIDs and cancer-related inflammation would provide new insights into this appealing strategy. In this review, the up-to-date advances in clinical and experimental researches targeting cancer-related inflammation with NSAIDs are presented, and the potential of pharmacogenomics are discussed as well.
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Affiliation(s)
- Hongjin Lai
- Institute of Thoracic Oncology and Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu, China,West China School of Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Yi Liu
- Institute of Thoracic Oncology and Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu, China,West China School of Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Juan Wu
- Department of Outpatient, West China Hospital, Sichuan University, Chengdu, China
| | - Jie Cai
- West China School of Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Hui Jie
- Institute of Thoracic Oncology and Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu, China
| | - Yuyang Xu
- Institute of Thoracic Oncology and Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu, China,*Correspondence: Yuyang Xu, ; Senyi Deng,
| | - Senyi Deng
- Institute of Thoracic Oncology and Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu, China,*Correspondence: Yuyang Xu, ; Senyi Deng,
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Al-Salihi M, Yi R, Wang S, Wu Q, Lin F, Qu J, Liu L. Quantitative laser-induced breakdown spectroscopy for discriminating neoplastic tissues from non-neoplastic ones. OPTICS EXPRESS 2021; 29:4159-4173. [PMID: 33771001 DOI: 10.1364/oe.410878] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
In this paper, we present a method to distinguish neoplastic tissues from non-neoplastic ones using calibration-free laser-induced breakdown spectroscopy (CF-LIBS). For this propose, plasma emission was collected from neoplastic and non-neoplastic tissues taken from the ovarian cancer mice models. Results were obtained by utilizing the characteristic plasma emission lines of different elements that have been confirmed in the investigated samples. From the temporal evolution of plasma emission, the optimum temporal-observation-windows are identified for LIBS investigation. The concentrations of the detected elements in tissues were measured by a calibration-free approach based on data process of plasma parameters at the local thermodynamic equilibrium. The neoplastic specimens provided more energetic plasma than non-neoplastic ones that resulting in higher peaks intensities, electron density and electron temperature especially in the early windows (between 0.1 µs to 0.8 µs). Results demonstrated higher concentrations of major and trace elements such as Mg, Fe, Ca, Na, and K in the neoplastic tissues. Finally, the results using CF-LIBS method were found to be in good agreement with that of Inductive coupled plasma-optical emission spectroscopy (ICP-OES).
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Liu K, Tsung K, Attenello FJ. Characterizing Cell Stress and GRP78 in Glioma to Enhance Tumor Treatment. Front Oncol 2020; 10:608911. [PMID: 33363039 PMCID: PMC7759649 DOI: 10.3389/fonc.2020.608911] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/11/2020] [Indexed: 02/06/2023] Open
Abstract
Glioblastoma (GBM) is the most common primary brain tumor, carrying a very poor prognosis, with median overall survival at about 12 to 15 months despite surgical resection, chemotherapy with temozolomide (TMZ), and radiation therapy. GBM recurs in the vast majority of patients, with recurrent tumors commonly displaying increase in resistance to standard of care chemotherapy, TMZ, as well as radiotherapy. One of the most commonly cited mechanisms of chemotherapeutic and radio-resistance occurs via the glucose-regulated protein 78 (GRP78), a well-studied mediator of the unfolded protein response (UPR), that has also demonstrated potential as a biomarker in GBM. Overexpression of GRP78 has been directly correlated with malignant tumor characteristics, including higher tumor grade, cellular proliferation, migration, invasion, poorer responses to TMZ and radiation therapy, and poorer patient outcomes. GRP78 expression is also higher in GBM tumor cells upon recurrence. Meanwhile, knockdown or suppression of GRP78 has been shown to sensitize cells to TMZ and radiation therapy. In light of these findings, various novel developing therapies are targeting GRP78 as monotherapies, combination therapies that enhance the effects of TMZ and radiation therapy, and as treatment delivery modalities. In this review, we delineate the mechanisms by which GRP78 has been noted to specifically modulate glioblastoma behavior and discuss current developing therapies involving GRP78 in GBM. While further research is necessary to translate these developing therapies into clinical settings, GRP78-based therapies hold promise in improving current standard-of-care GBM therapy and may ultimately lead to improved patient outcomes.
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Affiliation(s)
- Kristie Liu
- Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Kathleen Tsung
- Department of Neurosurgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Frank J Attenello
- Department of Neurosurgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
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Papp B, Launay S, Gélébart P, Arbabian A, Enyedi A, Brouland JP, Carosella ED, Adle-Biassette H. Endoplasmic Reticulum Calcium Pumps and Tumor Cell Differentiation. Int J Mol Sci 2020; 21:ijms21093351. [PMID: 32397400 PMCID: PMC7247589 DOI: 10.3390/ijms21093351] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/01/2020] [Accepted: 05/02/2020] [Indexed: 12/21/2022] Open
Abstract
Endoplasmic reticulum (ER) calcium homeostasis plays an essential role in cellular calcium signaling, intra-ER protein chaperoning and maturation, as well as in the interaction of the ER with other organelles. Calcium is accumulated in the ER by sarco/endoplasmic reticulum calcium ATPases (SERCA enzymes) that generate by active, ATP-dependent transport, a several thousand-fold calcium ion concentration gradient between the cytosol (low nanomolar) and the ER lumen (high micromolar). SERCA enzymes are coded by three genes that by alternative splicing give rise to several isoforms, which can display isoform-specific calcium transport characteristics. SERCA expression levels and isoenzyme composition vary according to cell type, and this constitutes a mechanism whereby ER calcium homeostasis is adapted to the signaling and metabolic needs of the cell, depending on its phenotype, its state of activation and differentiation. As reviewed here, in several normal epithelial cell types including bronchial, mammary, gastric, colonic and choroid plexus epithelium, as well as in mature cells of hematopoietic origin such as pumps are simultaneously expressed, whereas in corresponding tumors and leukemias SERCA3 expression is selectively down-regulated. SERCA3 expression is restored during the pharmacologically induced differentiation of various cancer and leukemia cell types. SERCA3 is a useful marker for the study of cell differentiation, and the loss of SERCA3 expression constitutes a previously unrecognized example of the remodeling of calcium homeostasis in tumors.
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Affiliation(s)
- Bela Papp
- Institut National de la Santé et de la Recherche Médicale, UMR U976, Institut Saint-Louis, 75010 Paris, France
- Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Université de Paris, 75010 Paris, France
- CEA, DRF-Institut Francois Jacob, Department of Hemato-Immunology Research, Hôpital Saint-Louis, 75010 Paris, France;
- Correspondence: or
| | - Sophie Launay
- EA481, UFR Santé, Université de Bourgogne Franche-Comté, 25000 Besançon, France;
| | - Pascal Gélébart
- Department of Clinical Science-Hematology Section, Haukeland University Hospital, University of Bergen, 5021 Bergen, Norway;
| | - Atousa Arbabian
- Laboratoire d’Innovation Vaccins, Institut Pasteur de Paris, 75015 Paris, France;
| | - Agnes Enyedi
- Second Department of Pathology, Semmelweis University, 1091 Budapest, Hungary;
| | - Jean-Philippe Brouland
- Institut Universitaire de Pathologie, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland;
| | - Edgardo D. Carosella
- CEA, DRF-Institut Francois Jacob, Department of Hemato-Immunology Research, Hôpital Saint-Louis, 75010 Paris, France;
| | - Homa Adle-Biassette
- AP-HP, Service d’Anatomie et Cytologie Pathologiques, Hôpital Lariboisière, 75010 Paris, France;
- Université de Paris, NeuroDiderot, Inserm UMR 1141, 75019 Paris, France
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Peterková L, Kmoníčková E, Ruml T, Rimpelová S. Sarco/Endoplasmic Reticulum Calcium ATPase Inhibitors: Beyond Anticancer Perspective. J Med Chem 2020; 63:1937-1963. [PMID: 32030976 DOI: 10.1021/acs.jmedchem.9b01509] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The sarco/endoplasmic reticulum calcium ATPase (SERCA), which plays a key role in the maintenance of Ca2+ ion homeostasis, is an extensively studied enzyme, the inhibition of which has a considerable impact on cell life and death decision. To date, several SERCA inhibitors have been thoroughly studied and the most notable one, a derivative of the sesquiterpene lactone thapsigargin, is gradually approaching a clinical application. Meanwhile, new compounds with SERCA-inhibiting properties of natural, synthetic, or semisynthetic origin are being discovered and/or developed; some of these might also be suitable for the development of new drugs with improved performance. This review brings an up-to-date comprehensive overview of recently discovered compounds with the potential of SERCA inhibition, discusses their mechanism of action, and highlights their potential clinical applications, such as cancer treatment.
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Affiliation(s)
- Lucie Peterková
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Eva Kmoníčková
- Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Silvie Rimpelová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic.,Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
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8
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Tran FH, Zheng JJ. Modulating the wnt signaling pathway with small molecules. Protein Sci 2017; 26:650-661. [PMID: 28120389 PMCID: PMC5368067 DOI: 10.1002/pro.3122] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 12/30/2022]
Abstract
Wnt signaling is a critical component during embryonic development and also plays an important role in regulating adult tissue homeostasis. Abnormal activation of Wnt signaling has been implicated in many cancers, while reduced activity of Wnt signaling leads to poor wound healing and structural formations. Thus, extensive efforts have been focused on developing small molecules that have potential to either inhibit or activate the pathway, hoping these molecules can offer leads for novel approaches in treating different human diseases. Many small-molecule inhibitors specifically target various elements, such as Frizzled, Disheveled, Porcupine, or Tankyrase, within the Wnt signaling pathways. These small molecules not only have the potential to be further developed as therapeutic reagents, but they may also be used as chemical probes to dissect the underlying mechanism of the Wnt signaling pathways. Therefore, their respective mechanisms and effective dosages are highly pertinent. Aiming to provide an overview of those molecules in a concise, easy-to-use manner, we summarize and organize the current research on them so that it may be helpful for utilization in different studies.
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Affiliation(s)
- Freddi Huan Tran
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine at UCLALos AngelesCalifornia90095
| | - Jie J. Zheng
- Department of Ophthalmology, Stein Eye Institute, David Geffen School of Medicine at UCLALos AngelesCalifornia90095
- Molecular Biology Institute, University of California, Los AngelesLos AngelesCalifornia90095
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Obacz J, Avril T, Le Reste PJ, Urra H, Quillien V, Hetz C, Chevet E. Endoplasmic reticulum proteostasis in glioblastoma—From molecular mechanisms to therapeutic perspectives. Sci Signal 2017; 10:10/470/eaal2323. [DOI: 10.1126/scisignal.aal2323] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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10
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Tian J, Liu R, Qu Q. Role of endoplasmic reticulum stress on cisplatin resistance in ovarian carcinoma. Oncol Lett 2017; 13:1437-1443. [PMID: 28454274 DOI: 10.3892/ol.2017.5580] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/14/2016] [Indexed: 12/16/2022] Open
Abstract
Endoplasmic reticulum (ER) is an essential site of cellular homeostasis regulation. ER stress (ERS) may induce autophagy in tumor cells that escape from apoptosis. The present study examined the effects and mechanism of ERS on cisplatin (DDP) sensitivity in ovarian carcinoma. SKOV3 tumor cells treated with Saquinavir were subjected to western blot and reverse transcription-quantitative polymerase chain reaction analysis to determine protein and messenger RNA (mRNA) expression levels of mechanistic target of rapamycin (mTOR) and Beclin 1. MTT assay was used to analyze the influence of Saquinavir on DDP resistance in SKOV3 cells. Saquinavir induced glucose-regulated protein 78 expression, which is a marker of ERS. Following treatment with various doses of Saquinavir, the sensitivity of ovarian cancer cells to DDP decreased significantly. Protein and mRNA expression levels of mTOR and Beclin 1 in SKOV3 cells were increased when the cells were exposed to Saquinavir or DDP for 24 h. Moreover, mTOR and Beclin 1 expression levels were highest in the Saquinavir + DDP group (0.684±0.072 and 0.6467±0.0468, respectively). SKOV3 tumor cells were also exposed to the autophagy inhibitor, 3-methyladenine (3-MA), and different concentrations of Saquinavir. Analysis of half maximal inhibitory concentration (IC50) values of DDP after this treatment demonstrated that IC50 values were significantly decreased compared with Saquinavir alone (P<0.001), suggesting that the sensitivity to DDP was improved in ovarian cancer cells after 3-MA exposure. These findings demonstrated that Saquinavir is able to induce ERS in SKOV3 cells effectively, and ER-induced stress may decrease the sensitivity of DDP in SKOV3 cells. Furthermore, ERS may regulate cell autophagy through the mTOR and Beclin 1 pathways, leading to a reduction in the sensitivity of DDP in SKOV3 cells. ERS in tumor cells and autophagy may be a potential target to improve the therapeutic effect of chemotherapy and reduce drug resistance in tumors.
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Affiliation(s)
- Jing Tian
- Department of Gynaecology, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Rong Liu
- Department of Gynaecology, Tianjin First Central Hospital, Tianjin 300192, P.R. China
| | - Quanxin Qu
- Department of Gynaecology, Tianjin First Central Hospital, Tianjin 300192, P.R. China
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Martinez NJ, Rai G, Yasgar A, Lea WA, Sun H, Wang Y, Luci DK, Yang SM, Nishihara K, Takeda S, Sagor M, Earnshaw I, Okada T, Mori K, Wilson K, Riggins GJ, Xia M, Grimaldi M, Jadhav A, Maloney DJ, Simeonov A. A High-Throughput Screen Identifies 2,9-Diazaspiro[5.5]Undecanes as Inducers of the Endoplasmic Reticulum Stress Response with Cytotoxic Activity in 3D Glioma Cell Models. PLoS One 2016; 11:e0161486. [PMID: 27570969 PMCID: PMC5003374 DOI: 10.1371/journal.pone.0161486] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/06/2016] [Indexed: 12/18/2022] Open
Abstract
The endoplasmic reticulum (ER) is involved in Ca2+ signaling and protein folding. ER Ca2+ depletion and accumulation of unfolded proteins activate the molecular chaperone GRP78 (glucose-regulated protein 78) which in turn triggers the ER stress response (ERSR) pathway aimed to restore ER homeostasis. Failure to adapt to stress, however, results in apoptosis. We and others have shown that malignant cells are more susceptible to ERSR-induced apoptosis than their normal counterparts, implicating the ERSR as a potential target for cancer therapeutics. Predicated on these findings, we developed an assay that uses a GRP78 biosensor to identify small molecule activators of ERSR in glioma cells. We performed a quantitative high-throughput screen (qHTS) against a collection of ~425,000 compounds and a comprehensive panel of orthogonal secondary assays was formulated for stringent compound validation. We identified novel activators of ERSR, including a compound with a 2,9-diazaspiro[5.5]undecane core, which depletes intracellular Ca2+ stores and induces apoptosis-mediated cell death in several cancer cell lines, including patient-derived and 3D cultures of glioma cells. This study demonstrates that our screening platform enables the identification and profiling of ERSR inducers with cytotoxic activity and advocates for characterization of these compound in in vivo models.
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Affiliation(s)
- Natalia J. Martinez
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Ganesha Rai
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Adam Yasgar
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Wendy A. Lea
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Hongmao Sun
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Yuhong Wang
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Diane K. Luci
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Shyh-Ming Yang
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Kana Nishihara
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Kyoto 606–8501, Japan
| | - Shunichi Takeda
- Department of Neurosurgery, John Hopkins University, Baltimore, MD 21231, United States of America
| | - Mohiuddin Sagor
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Kyoto 606–8501, Japan
| | - Irina Earnshaw
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Kyoto 606–8501, Japan
| | - Tetsuya Okada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606–8502, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606–8502, Japan
| | - Kelli Wilson
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
- Department of Neurosurgery, John Hopkins University, Baltimore, MD 21231, United States of America
| | - Gregory J. Riggins
- Department of Neurosurgery, John Hopkins University, Baltimore, MD 21231, United States of America
| | - Menghang Xia
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - Maurizio Grimaldi
- Laboratory of Neuropharmacology, Department of Biochemistry and Molecular Biology, Southern Research Institute, Birmingham, AL 35205, United States of America
| | - Ajit Jadhav
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
| | - David J. Maloney
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
- * E-mail: (AS); (DJM)
| | - Anton Simeonov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, 20850, United States of America
- * E-mail: (AS); (DJM)
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Chang J, Xue M, Yang S, Yao B, Zhang B, Chen X, Pozzi A, Zhang MZ. Inhibition of 11β-Hydroxysteroid Dehydrogenase Type II Suppresses Lung Carcinogenesis by Blocking Tumor COX-2 Expression as Well as the ERK and mTOR Signaling Pathways. PLoS One 2015; 10:e0127030. [PMID: 26011146 PMCID: PMC4444260 DOI: 10.1371/journal.pone.0127030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 04/10/2015] [Indexed: 12/31/2022] Open
Abstract
Lung cancer is by far the leading cause of cancer death. Early diagnosis and prevention remain the best approach to reduce the overall morbidity and mortality. Experimental and clinical evidence have shown that cyclooxygenase-2 (COX-2) derived prostaglandin E2 (PGE2) contributes to lung tumorigenesis. COX-2 inhibitors suppress the development and progression of lung cancer. However, increased cardiovascular risks of COX-2 inhibitors limit their use in chemoprevention of lung cancers. Glucocorticoids are endogenous and potent COX-2 inhibitors, and their local actions are down-regulated by 11β–hydroxysteroid dehydrogenase type II (11ßHSD2)-mediated metabolism. We found that 11βHSD2 expression was increased in human lung cancers and experimental lung tumors. Inhibition of 11βHSD2 activity enhanced glucocorticoid-mediated COX-2 inhibition in human lung carcinoma cells. Furthermore, 11βHSD2 inhibition suppressed lung tumor growth and invasion in association with increased tissue active glucocorticoid levels, decreased COX-2 expression, inhibition of ERK and mTOR signaling pathways, increased tumor endoplasmic reticulum stress as well as increased lifespan. Therefore, 11βHSD2 inhibition represents a novel approach for lung cancer chemoprevention and therapy by increasing tumor glucocorticoid activity, which in turn selectively blocks local COX-2 activity and/or inhibits the ERK and mTOR signaling pathways.
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Affiliation(s)
- Jian Chang
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Min Xue
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Shilin Yang
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Bing Yao
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Bixiang Zhang
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Xiaoping Chen
- Hepatic Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Ambra Pozzi
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Ming-Zhi Zhang
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical College, Xuzhou, China
- * E-mail:
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Mügge FL, Silva AM. Endoplasmic reticulum stress response in the roadway for the effects of non-steroidal anti-inflammatory drugs. ENDOPLASMIC RETICULUM STRESS IN DISEASES 2015. [DOI: 10.1515/ersc-2015-0001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractOver the past decade, a handful of evidence has been provided that nonsteroidal anti-inflammatory drugs (NSAIDs) display effects on the homeostasis of the endoplasmic reticulum (ER). Their uptake into cells will eventually lead to activation or inhibition of key molecules that mediate ER stress responses, raising not only a growing interest for a pharmacological target in ER stress responses but also important questions how the ER-stress mediated effects induced by NSAIDs could be therapeutically advantageous or not. We review here the toxicity effects and therapeutic applications of NSAIDs involving the three majors ER stress arms namely PERK, IRE1, and ATF6. First, we provide brief introduction on the well-established and characterized downstream events mediated by these ER stress players, followed by presentation of the NSAIDs compounds and mode of action, and finally their effects on ER stress response. NSAIDs present promising drug agents targeting the components of ER stress in different aspects of cancer and other diseases, but a better comprehension of the mechanisms underlying their benefits and harms will certainly pave the road for several diseases’ therapy.
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Celecoxib Inhibits Prion Protein 90-231-Mediated Pro-inflammatory Responses in Microglial Cells. Mol Neurobiol 2014; 53:57-72. [PMID: 25404089 DOI: 10.1007/s12035-014-8982-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/03/2014] [Indexed: 12/21/2022]
Abstract
Activation of microglia is a central event in the atypical inflammatory response occurring during prion encephalopathies. We report that the prion protein fragment encompassing amino acids 90-231 (PrP90-231), a model of the neurotoxic activity of the pathogenic prion protein (PrP(Sc)), causes activation of both primary microglia cultures and N9 microglial cells in vitro. This effect was characterized by cell proliferation arrest and induction of a secretory phenotype, releasing prostaglandin E2 (PGE2) and nitric oxide (NO). Conditioned medium from PrP90-231-treated microglia induced in vitro cytotoxicity of A1 mesencephalic neurons, supporting the notion that soluble mediators released by activated microglia contributes to the neurodegeneration during prion diseases. The neuroinflammatory role of COX activity, and its potential targeting for anti-prion therapies, was tested measuring the effects of ketoprofen and celecoxib (preferential inhibitors of COX1 and COX2, respectively) on PrP90-231-induced microglial activation. Celecoxib, but not ketoprofen significantly reverted the growth arrest as well as NO and PGE2 secretion induced by PrP90-231, indicating that PrP90-231 pro-inflammatory response in microglia is mainly dependent on COX2 activation. Taken together, these data outline the importance of microglia in the neurotoxicity occurring during prion diseases and highlight the potentiality of COX2-selective inhibitors to revert microglia as adjunctive pharmacological approach to contrast the neuroinflammation-dependent neurotoxicity.
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15
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Johnson GG, White MC, Wu JH, Vallejo M, Grimaldi M. The deadly connection between endoplasmic reticulum, Ca2+, protein synthesis, and the endoplasmic reticulum stress response in malignant glioma cells. Neuro Oncol 2014; 16:1086-99. [PMID: 24569545 DOI: 10.1093/neuonc/nou012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The endoplasmic reticulum (ER) is involved in Ca(2+) signaling and protein processing. Accumulation of unfolded proteins following ER Ca(2+) depletion triggers the ER stress response (ERSR), which facilitates protein folding and removal of damaged proteins and can induce cell death. Unfolded proteins bind to chaperones, such as the glucose-regulated protein (GRP)78 and cause the release of GRP78-repressed proteins executing ERSR. METHODS Several glioma cell lines and primary astrocytes were used to analyze ERSR using standard western blots, reverse transcription-PCR, viability assays, and single cell Ca(2+) imaging. RESULTS ERSR induction with thapsigargin results in a more intense ERSR associated with a larger loss of ER Ca(2+), activation of ER-associated caspases (4/12) and caspase 3, and a higher rate of malignant glioma cell death than in normal glial cells. Malignant glioma cells have higher levels of protein synthesis and expression of the translocon (a component of the ribosomal complex, guiding protein entry in the ER), the activity of which is associated with the loss of ER Ca(2+). Our experiments confirm increased expression of the translocon in malignant glioma cells. In addition, blockade of the ribosome-translocon complex with agents differently affecting translocon Ca(2+) permeability causes opposite effects on ERSR deployment and death of malignant glioma cells. CONCLUSIONS Excessive ER Ca(2+) loss due to translocon activity appears to be responsible for the enhancement of ERSR, leading to the death of glioma cells. The results reveal a characteristic of malignant glioma cells that could be exploited to develop new therapeutic strategies to treat incurable glial malignancies.
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Affiliation(s)
- Guyla G Johnson
- Laboratory of Neuropharmacology, Department of Biochemistry and Molecular Biology, Southern Research Institute, Birmingham, Alabama (G.G.J., M.C.W., J-H.W., M.G.); Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama (M.V.)
| | - Misti C White
- Laboratory of Neuropharmacology, Department of Biochemistry and Molecular Biology, Southern Research Institute, Birmingham, Alabama (G.G.J., M.C.W., J-H.W., M.G.); Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama (M.V.)
| | - Jian-He Wu
- Laboratory of Neuropharmacology, Department of Biochemistry and Molecular Biology, Southern Research Institute, Birmingham, Alabama (G.G.J., M.C.W., J-H.W., M.G.); Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama (M.V.)
| | - Matthew Vallejo
- Laboratory of Neuropharmacology, Department of Biochemistry and Molecular Biology, Southern Research Institute, Birmingham, Alabama (G.G.J., M.C.W., J-H.W., M.G.); Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama (M.V.)
| | - Maurizio Grimaldi
- Laboratory of Neuropharmacology, Department of Biochemistry and Molecular Biology, Southern Research Institute, Birmingham, Alabama (G.G.J., M.C.W., J-H.W., M.G.); Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama (M.V.)
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Liggett JL, Zhang X, Eling TE, Baek SJ. Anti-tumor activity of non-steroidal anti-inflammatory drugs: cyclooxygenase-independent targets. Cancer Lett 2014; 346:217-24. [PMID: 24486220 DOI: 10.1016/j.canlet.2014.01.021] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/21/2014] [Accepted: 01/22/2014] [Indexed: 12/27/2022]
Abstract
Non-steroidal anti-inflammatory drugs (NSAIDs) are used extensively for analgesic and antipyretic treatments. In addition, NSAIDs reduce the risk and mortality to several cancers. Their mechanisms in anti-tumorigenesis are not fully understood, but both cyclooxygenase (COX)-dependent and -independent pathways play a role. We and others have been interested in elucidating molecular targets of NSAID-induced apoptosis. In this review, we summarize updated literature regarding cellular and molecular targets modulated by NSAIDs. Among those NSAIDs, sulindac sulfide and tolfenamic acid are emphasized in this review because these two drugs have been well investigated for their anti-tumorigenic activity in many different types of cancer.
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Affiliation(s)
- Jason L Liggett
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996 USA
| | - Xiaobo Zhang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Thomas E Eling
- Laboratory of Molecular Carcinogenesis, National Institutes of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
| | - Seung Joon Baek
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996 USA.
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Doudican NA, Wen SY, Mazumder A, Orlow SJ. Identification of agents that promote endoplasmic reticulum stress using an assay that monitors luciferase secretion. ACTA ACUST UNITED AC 2013; 19:575-84. [PMID: 24371212 DOI: 10.1177/1087057113517549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Disruption of protein processing in the secretory pathway is a measurable hallmark of endoplasmic reticulum (ER) stress. Activation of ER stress-mediated pathways has been implicated in numerous diseases, including cancer. To identify agents that induce ER stress, we established a screen for compounds that reduce secretion of the reporter protein Gaussia luciferase (GLUC). Given the clinically validated importance of targeting ER stress-mediated pathways in the treatment of multiple myeloma (MM), we used this hematological malignancy as a model for validating our screening system. From a screen of 2000 marketed drugs and natural compounds in KMS11 and ARP1 MM cells, we identified 97 agents that reduced GLUC secretion in both cell lines by at least 30%. To confirm inducers of ER stress, we applied a secondary screen that assessed splicing of the unfolded protein response (UPR) transcription factor XBP1. One agent, theaflavin-3,3'-digallate (TF-3), was chosen based on its history of safe human consumption and further validated through studies of ER stress-related pathways, including the UPR and apoptosis. Given these promising results, this screen could be a useful tool to identify agents targeting ER stress-related mechanisms in other cellular systems wherein ER stress plays a role in disease etiology.
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Affiliation(s)
- Nicole A Doudican
- 1The Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, NY, USA
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18
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Abstract
Numerous epidemiologic studies have reported that the long-term use of nonsteroidal anti-inflammatory drugs (NSAID) is associated with a significant decrease in cancer incidence and delayed progression of malignant disease. The use of NSAIDs has also been linked with reduced risk from cancer-related mortality and distant metastasis. Certain prescription-strength NSAIDs, such as sulindac, have been shown to cause regression of precancerous lesions. Unfortunately, the extended use of NSAIDs for chemoprevention results in potentially fatal side effects related to their COX-inhibitory activity and suppression of prostaglandin synthesis. Although the basis for the tumor growth-inhibitory activity of NSAIDs likely involves multiple effects on tumor cells and their microenvironment, numerous investigators have concluded that the underlying mechanism is not completely explained by COX inhibition. It may therefore be possible to develop safer and more efficacious drugs by targeting such COX-independent mechanisms. NSAID derivatives or metabolites that lack COX-inhibitory activity, but retain or have improved anticancer activity, support this possibility. Experimental studies suggest that apoptosis induction and suppression of β-catenin-dependent transcription are important aspects of their antineoplastic activity. Studies show that the latter involves phosphodiesterase inhibition and the elevation of intracellular cyclic GMP levels. Here, we review the evidence for COX-independent mechanisms and discuss progress toward identifying alternative targets and developing NSAID derivatives that lack COX-inhibitory activity but have improved antineoplastic properties.
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Affiliation(s)
- Evrim Gurpinar
- Authors' Affiliations: Department of Pharmacology and Toxicology; Department of Pathology, The University of Alabama at Birmingham, Birmingham; and Drug Discovery Research Center, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama
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Gurpinar E, Grizzle WE, Piazza GA. COX-Independent Mechanisms of Cancer Chemoprevention by Anti-Inflammatory Drugs. Front Oncol 2013; 3:181. [PMID: 23875171 PMCID: PMC3708159 DOI: 10.3389/fonc.2013.00181] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 06/26/2013] [Indexed: 12/21/2022] Open
Abstract
Epidemiological and clinical studies suggest that non-steroidal anti-inflammatory drugs (NSAIDs), including cyclooxygenase (COX)-2 selective inhibitors, reduce the risk of developing cancer. Experimental studies in human cancer cell lines and rodent models of carcinogenesis support these observations by providing strong evidence for the antineoplastic properties of NSAIDs. The involvement of COX-2 in tumorigenesis and its overexpression in various cancer tissues suggest that inhibition of COX-2 is responsible for the chemopreventive efficacy of these agents. However, the precise mechanisms by which NSAIDs exert their antiproliferative effects are still a matter of debate. Numerous other studies have shown that NSAIDs can act through COX-independent mechanisms. This review provides a detailed description of the major COX-independent molecular targets of NSAIDs and discusses how these targets may be involved in their anticancer effects. Toxicities resulting from COX inhibition and the suppression of prostaglandin synthesis preclude the long-term use of NSAIDs for cancer chemoprevention. Furthermore, chemopreventive efficacy is incomplete and treatment often leads to the development of resistance. Identification of alternative NSAID targets and elucidation of the biochemical processes by which they inhibit tumor growth could lead to the development of safer and more efficacious drugs for cancer chemoprevention.
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Affiliation(s)
- Evrim Gurpinar
- Department of Pharmacology and Toxicology, The University of Alabama at Birmingham , Birmingham, AL , USA
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20
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Click RE. Anticancer activity and chemoprevention of xenobiotic organosulfurs in preclinical model systems. ACTA ACUST UNITED AC 2013; 1. [PMID: 25383193 PMCID: PMC4222532 DOI: 10.7243/2052-6199-1-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
There seems to be little doubt that xenobiotic and plant derived organosulfur compounds have enormous benefits for in vitro cellular functions and for a multitude of diseases, including cancer. Since there are numerous reviews on anticancer activities of plant organosulfurs, the focus herein will be on alterations associated with xenobiotic organosulfurs. Benefits of 2-mercaptoethanol (2-Me), N-Acetyl-cysteine, cysteamine, thioproline, piroxicam, disulfiram, amifostine, sulindac, celecoxib, oltipraz and their derivates on transplanted homologous tumors and on autochthonous cancers with a viral-, radiation-, chemical carcinogen-, and undefined-etiology are assessed. Because all organosulfurs were not tested for activity in each of the etiology categories, comparative evaluations are restricted. In general, all ‘appeared’ to lower the incidence of cancer irrespective of etiology; however, since most of these values were determined at ages much younger than at a natural-end-of-life-age, differences most likely, instead, reflect a delayed initiation and/or a slowed progression of tumorigenesis. The poorest, long-term benefits of early intervention protocols occurred for viral- and chemical carcinogen-induced cancers. In addition, once tumorigenesis was beyond the initiation stage, outcomes of organosulfur therapies were extremely poor, indicating that they will not be of significant value as stand alone treatments. More importantly, except for the lifetime prevention of spontaneous and radiation-induced mammary tumors by daily dietary 2-Me, similar life long prevention of tumorigenesis was not achieved with other xenobiotics or any of nature’s plant organosulfurs. These results raise an interesting question: Is the variability in incidence found for different organosulfurs associated with (a) their structure, (b) the length of the untreated latency period, (c) treatment duration/dose, and/or (d) the etiology-inducing agent?
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