Sequoiacrone
May 20th, 2009, 04:20 AM
Marijuana compound fights brain cancer: Study
(http://www.examiner.com/x-8543-SF-Health-News-Examiner)
May 18, 12:59 PM
[/URL]
http://image.examiner.com/images/blog/wysiwyg/image/Zen_Healing--CC-Caveman_92223.jpg
The active chemical compound in marijuana aggressively targets
brain cancer cells, and helps to kill them by encouraging them to
dissolve themselves, according to a recent report by Spanish
researchers. Above is a sign from the Zen Healing Collective,
West Hollywood, CA. Photo: CreativeCommons/Caveman 92223
See marijuana slideshow below.
Guillermo Velasco and a team of researchers at Complutense University in Spain have shown that the psycho-active chemical in marijuana, delta-9-tetrahydrocannibinol (THC), encourages brain cancer cells to begin a process called autophagy, in which the cell basically dissolves itself.
The team noted that cannabinoids such as THC showed cancer-fighting effects in mice implanted with human brain cancer cells and in human patients with brain tumors. When mice implanted with human brain cancer cells that received the THC, showed significant reduction of tumor growth.
Two patients enrolled in a clinical trial received THC directly to the brain as an experimental treatment for recurrent glioblastoma multiforme, a highly aggressive brain tumor. A comparison of biopsies taken before and after treatment showed that that tumors showed increased autophagy activity after receiving the THC.
None of the patients showed toxic effects from the treatment. Earlier assessments of THC in cancer treatment have also shown the therapy to be well tolerated. The researchers say that these findings might lead to new approaches for fighting tumor growth in brain cancer.
The findings appear in the April issue of the Journal of Clinical Investigation (javascript:void(0)).
Research Article
Cannabinoid action induces autophagy-mediated cell death through stimulation of ER stress in human glioma cells
María Salazar1,2, Arkaitz Carracedo1, Íñigo J. Salanueva1, Sonia Hernández-Tiedra1, Mar Lorente1,2, Ainara Egia1, Patricia Vázquez3, Cristina Blázquez1,2, Sofía Torres1, Stephane García4, Jonathan Nowak4, Gian María Fimia5, Mauro Piacentini5, Francesco Cecconi6, Pier Paolo Pandolfi7, Luis González-Feria8, Juan L. Iovanna4, Manuel Guzmán1,2, Patricia Boya3 and Guillermo Velasco1,2
1Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, Madrid, Spain.
2Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
33D Lab (Development, Differentiation, and Degeneration), Department of Cellular and Molecular Physiopathology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
4INSERM U624, Campus de Luminy, Marseille, France.
5National Institute for Infectious Diseases, IRCCS “L. Spallanzani,” Rome, Italy.
6Laboratory of Molecular Neuroembryology, IRCCS Fondazione Santa Lucia and Department of Biology, University of Rome “Tor Vergata,” Rome, Italy.
7Cancer Genetics Program, Beth Israel Deaconess Cancer Center and Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
8Department of Neurosurgery, University Hospital, Tenerife, Spain.
Address correspondence to: Guillermo Velasco, Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, c/ José Antonio Novais s/n, 28040 Madrid, Spain. Phone: 34-913944668; Fax: 34-913944672; E-mail: gvd@bbm1.ucm.es.
First published April 1, 2009
Received for publication November 3, 2008, and accepted in revised form February 11, 2009.
Autophagy can promote cell survival or cell death, but the molecular basis underlying its dual role in cancer remains obscure. Here we demonstrate that Δ9-tetrahydrocannabinol (THC), the main active component of marijuana, induces human glioma cell death through stimulation of autophagy. Our data indicate that THC induced ceramide accumulation and eukaryotic translation initiation factor 2α (eIF2α) phosphorylation and thereby activated an ER stress response that promoted autophagy via tribbles homolog 3–dependent (TRB3-dependent) inhibition of the Akt/mammalian target of rapamycin complex 1 (mTORC1) axis. We also showed that autophagy is upstream of apoptosis in cannabinoid-induced human and mouse cancer cell death and that activation of this pathway was necessary for the antitumor action of cannabinoids in vivo. These findings describe a mechanism by which THC can promote the autophagic death of human and mouse cancer cells and provide evidence that cannabinoid administration may be an effective therapeutic strategy for targeting human cancers.
Introduction
Macro-autophagy, hereafter referred to as “autophagy,” is a highly conserved cellular process in which cytoplasmic materials — including organelles — are sequestered into double-membrane vesicles called autophagosomes and delivered to lysosomes for degradation or recycling (1 (http://www.jci.org/articles/view/37948#B1)). In many cellular settings, triggering of autophagy relies on the inhibition of mammalian target of rapamycin complex 1 (mTORC1), an event that promotes the activation (de-inhibition) of several autophagy proteins (Atgs) involved in the initial phase of membrane isolation (1 (http://www.jci.org/articles/view/37948#B1)). Enlargement of this complex to form the autophagosome requires the participation of 2 ubiquitin-like conjugation systems. One involves the conjugation of ATG12 to ATG5 and the other of phosphatidylethanolamine to LC3/ATG8 (1 (http://www.jci.org/articles/view/37948#B1)). The final outcome of the activation of the autophagy program is highly dependent on the cellular context and the strength and duration of the stress-inducing signals (2 (http://www.jci.org/articles/view/37948#B2)–5 (http://www.jci.org/articles/view/37948#B5)). Thus, besides its role in cellular homeostasis, autophagy can be a form of programmed cell death, designated “type II programmed cell death,” or play a cytoprotective role, for example in situations of nutrient starvation (6 (http://www.jci.org/articles/view/37948#B6)). Accordingly, autophagy has been proposed to play an important role in both tumor progression and promotion of cancer cell death (2 (http://www.jci.org/articles/view/37948#B2)–4 (http://www.jci.org/articles/view/37948#B4)), although the molecular mechanisms responsible for this dual action of autophagy in cancer have not been elucidated.
Δ9-Tetrahydrocannabinol (THC), the main active component of marijuana (7 (http://www.jci.org/articles/view/37948#B7)), exerts a wide variety of biological effects by mimicking endogenous substances — the endocannabinoids — that bind to and activate specific cannabinoid receptors (8 (http://www.jci.org/articles/view/37948#B8)). One of the most exciting areas of research in the cannabinoid field is the study of the potential application of cannabinoids as antitumoral agents (9 (http://www.jci.org/articles/view/37948#B9)). Cannabinoid administration has been found to curb the growth of several types of tumor xenografts in rats and mice (9 (http://www.jci.org/articles/view/37948#B9), 10 (http://www.jci.org/articles/view/37948#B10)). Based on this preclinical evidence, a pilot clinical trial has been recently run to investigate the antitumoral action of THC on recurrent gliomas (11 (http://www.jci.org/articles/view/37948#B11)). Recent findings have also shown that the pro-apoptotic and tumor growth–inhibiting activity of cannabinoids relies on the upregulation of the transcriptional co-activator p8 (12 (http://www.jci.org/articles/view/37948#B12)) and its target the pseudo-kinase tribbles homolog 3 (TRB3) (13 (http://www.jci.org/articles/view/37948#B13)). However, the mechanisms that promote the activation of this signaling route as well as the targets downstream of TRB3 that mediate its tumor cell–killing action remain elusive. In this study we found that ER stress–evoked upregulation of the p8/TRB3 pathway induced autophagy via inhibition of the Akt/mTORC1 axis and that activation of autophagy promoted the apoptotic death of tumor cells. The uncovering of this pathway, which we believe is novel, for promoting tumor cell death may have therapeutic implications in the treatment of cancer.
Results
Autophagy mediates THC-induced cancer cell death. As a first approach to gain insight into the morphological changes induced in cancer cells by cannabinoid administration, we performed electron microscopy analysis of U87MG human astrocytoma cells. Interestingly, double membrane vacuolar structures with the morphological features of autophagosomes were observed in THC-treated cells (Figure 1 (http://www.jci.org/articles/view/37948#F1), A–C). The conversion of the soluble form of LC3 (LC3-I) to the lipidated and autophagosome-associated form (LC3-II) is considered one of the hallmarks of autophagy (1 (http://www.jci.org/articles/view/37948#B1)), and thus we observed the occurrence of LC3-positive dots as well as the appearance of LC3-II (Figure 1 (http://www.jci.org/articles/view/37948#F1)D) in cannabinoid-challenged cells. In addition, co-incubation with the lysosomal protease inhibitors E64d and pepstatin A, which blocks the last steps of autophagic degradation (14 (http://www.jci.org/articles/view/37948#B14)), enhanced THC-induced accumulation of LC3-II (Figure 1 (http://www.jci.org/articles/view/37948#F1)E), confirming that cannabinoids induce dynamic autophagy in U87MG cells. Furthermore, incubation with the cannabinoid receptor 1 (CB1) antagonist SR141716 prevented THC-induced LC3 lipidation and formation of LC3 dots (Figure 1 (http://www.jci.org/articles/view/37948#F1)D), indicating that induction of autophagy by cannabinoids relies on CB1 receptor activation.
For the entire article see here:
[url]http://www.jci.org/articles/view/37948
(http://www.examiner.com/x-8543-SF-Health-News-Examiner)
May 18, 12:59 PM
[/URL]
http://image.examiner.com/images/blog/wysiwyg/image/Zen_Healing--CC-Caveman_92223.jpg
The active chemical compound in marijuana aggressively targets
brain cancer cells, and helps to kill them by encouraging them to
dissolve themselves, according to a recent report by Spanish
researchers. Above is a sign from the Zen Healing Collective,
West Hollywood, CA. Photo: CreativeCommons/Caveman 92223
See marijuana slideshow below.
Guillermo Velasco and a team of researchers at Complutense University in Spain have shown that the psycho-active chemical in marijuana, delta-9-tetrahydrocannibinol (THC), encourages brain cancer cells to begin a process called autophagy, in which the cell basically dissolves itself.
The team noted that cannabinoids such as THC showed cancer-fighting effects in mice implanted with human brain cancer cells and in human patients with brain tumors. When mice implanted with human brain cancer cells that received the THC, showed significant reduction of tumor growth.
Two patients enrolled in a clinical trial received THC directly to the brain as an experimental treatment for recurrent glioblastoma multiforme, a highly aggressive brain tumor. A comparison of biopsies taken before and after treatment showed that that tumors showed increased autophagy activity after receiving the THC.
None of the patients showed toxic effects from the treatment. Earlier assessments of THC in cancer treatment have also shown the therapy to be well tolerated. The researchers say that these findings might lead to new approaches for fighting tumor growth in brain cancer.
The findings appear in the April issue of the Journal of Clinical Investigation (javascript:void(0)).
Research Article
Cannabinoid action induces autophagy-mediated cell death through stimulation of ER stress in human glioma cells
María Salazar1,2, Arkaitz Carracedo1, Íñigo J. Salanueva1, Sonia Hernández-Tiedra1, Mar Lorente1,2, Ainara Egia1, Patricia Vázquez3, Cristina Blázquez1,2, Sofía Torres1, Stephane García4, Jonathan Nowak4, Gian María Fimia5, Mauro Piacentini5, Francesco Cecconi6, Pier Paolo Pandolfi7, Luis González-Feria8, Juan L. Iovanna4, Manuel Guzmán1,2, Patricia Boya3 and Guillermo Velasco1,2
1Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, Madrid, Spain.
2Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
33D Lab (Development, Differentiation, and Degeneration), Department of Cellular and Molecular Physiopathology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
4INSERM U624, Campus de Luminy, Marseille, France.
5National Institute for Infectious Diseases, IRCCS “L. Spallanzani,” Rome, Italy.
6Laboratory of Molecular Neuroembryology, IRCCS Fondazione Santa Lucia and Department of Biology, University of Rome “Tor Vergata,” Rome, Italy.
7Cancer Genetics Program, Beth Israel Deaconess Cancer Center and Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
8Department of Neurosurgery, University Hospital, Tenerife, Spain.
Address correspondence to: Guillermo Velasco, Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, c/ José Antonio Novais s/n, 28040 Madrid, Spain. Phone: 34-913944668; Fax: 34-913944672; E-mail: gvd@bbm1.ucm.es.
First published April 1, 2009
Received for publication November 3, 2008, and accepted in revised form February 11, 2009.
Autophagy can promote cell survival or cell death, but the molecular basis underlying its dual role in cancer remains obscure. Here we demonstrate that Δ9-tetrahydrocannabinol (THC), the main active component of marijuana, induces human glioma cell death through stimulation of autophagy. Our data indicate that THC induced ceramide accumulation and eukaryotic translation initiation factor 2α (eIF2α) phosphorylation and thereby activated an ER stress response that promoted autophagy via tribbles homolog 3–dependent (TRB3-dependent) inhibition of the Akt/mammalian target of rapamycin complex 1 (mTORC1) axis. We also showed that autophagy is upstream of apoptosis in cannabinoid-induced human and mouse cancer cell death and that activation of this pathway was necessary for the antitumor action of cannabinoids in vivo. These findings describe a mechanism by which THC can promote the autophagic death of human and mouse cancer cells and provide evidence that cannabinoid administration may be an effective therapeutic strategy for targeting human cancers.
Introduction
Macro-autophagy, hereafter referred to as “autophagy,” is a highly conserved cellular process in which cytoplasmic materials — including organelles — are sequestered into double-membrane vesicles called autophagosomes and delivered to lysosomes for degradation or recycling (1 (http://www.jci.org/articles/view/37948#B1)). In many cellular settings, triggering of autophagy relies on the inhibition of mammalian target of rapamycin complex 1 (mTORC1), an event that promotes the activation (de-inhibition) of several autophagy proteins (Atgs) involved in the initial phase of membrane isolation (1 (http://www.jci.org/articles/view/37948#B1)). Enlargement of this complex to form the autophagosome requires the participation of 2 ubiquitin-like conjugation systems. One involves the conjugation of ATG12 to ATG5 and the other of phosphatidylethanolamine to LC3/ATG8 (1 (http://www.jci.org/articles/view/37948#B1)). The final outcome of the activation of the autophagy program is highly dependent on the cellular context and the strength and duration of the stress-inducing signals (2 (http://www.jci.org/articles/view/37948#B2)–5 (http://www.jci.org/articles/view/37948#B5)). Thus, besides its role in cellular homeostasis, autophagy can be a form of programmed cell death, designated “type II programmed cell death,” or play a cytoprotective role, for example in situations of nutrient starvation (6 (http://www.jci.org/articles/view/37948#B6)). Accordingly, autophagy has been proposed to play an important role in both tumor progression and promotion of cancer cell death (2 (http://www.jci.org/articles/view/37948#B2)–4 (http://www.jci.org/articles/view/37948#B4)), although the molecular mechanisms responsible for this dual action of autophagy in cancer have not been elucidated.
Δ9-Tetrahydrocannabinol (THC), the main active component of marijuana (7 (http://www.jci.org/articles/view/37948#B7)), exerts a wide variety of biological effects by mimicking endogenous substances — the endocannabinoids — that bind to and activate specific cannabinoid receptors (8 (http://www.jci.org/articles/view/37948#B8)). One of the most exciting areas of research in the cannabinoid field is the study of the potential application of cannabinoids as antitumoral agents (9 (http://www.jci.org/articles/view/37948#B9)). Cannabinoid administration has been found to curb the growth of several types of tumor xenografts in rats and mice (9 (http://www.jci.org/articles/view/37948#B9), 10 (http://www.jci.org/articles/view/37948#B10)). Based on this preclinical evidence, a pilot clinical trial has been recently run to investigate the antitumoral action of THC on recurrent gliomas (11 (http://www.jci.org/articles/view/37948#B11)). Recent findings have also shown that the pro-apoptotic and tumor growth–inhibiting activity of cannabinoids relies on the upregulation of the transcriptional co-activator p8 (12 (http://www.jci.org/articles/view/37948#B12)) and its target the pseudo-kinase tribbles homolog 3 (TRB3) (13 (http://www.jci.org/articles/view/37948#B13)). However, the mechanisms that promote the activation of this signaling route as well as the targets downstream of TRB3 that mediate its tumor cell–killing action remain elusive. In this study we found that ER stress–evoked upregulation of the p8/TRB3 pathway induced autophagy via inhibition of the Akt/mTORC1 axis and that activation of autophagy promoted the apoptotic death of tumor cells. The uncovering of this pathway, which we believe is novel, for promoting tumor cell death may have therapeutic implications in the treatment of cancer.
Results
Autophagy mediates THC-induced cancer cell death. As a first approach to gain insight into the morphological changes induced in cancer cells by cannabinoid administration, we performed electron microscopy analysis of U87MG human astrocytoma cells. Interestingly, double membrane vacuolar structures with the morphological features of autophagosomes were observed in THC-treated cells (Figure 1 (http://www.jci.org/articles/view/37948#F1), A–C). The conversion of the soluble form of LC3 (LC3-I) to the lipidated and autophagosome-associated form (LC3-II) is considered one of the hallmarks of autophagy (1 (http://www.jci.org/articles/view/37948#B1)), and thus we observed the occurrence of LC3-positive dots as well as the appearance of LC3-II (Figure 1 (http://www.jci.org/articles/view/37948#F1)D) in cannabinoid-challenged cells. In addition, co-incubation with the lysosomal protease inhibitors E64d and pepstatin A, which blocks the last steps of autophagic degradation (14 (http://www.jci.org/articles/view/37948#B14)), enhanced THC-induced accumulation of LC3-II (Figure 1 (http://www.jci.org/articles/view/37948#F1)E), confirming that cannabinoids induce dynamic autophagy in U87MG cells. Furthermore, incubation with the cannabinoid receptor 1 (CB1) antagonist SR141716 prevented THC-induced LC3 lipidation and formation of LC3 dots (Figure 1 (http://www.jci.org/articles/view/37948#F1)D), indicating that induction of autophagy by cannabinoids relies on CB1 receptor activation.
For the entire article see here:
[url]http://www.jci.org/articles/view/37948