Ernährung und Vitamine > Ernährung

Methionin-arme Diät soll Wirksamkeit von Chemotherapie erhöhen

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Johanna Teig:
Hier geht es um eine neue Diät, die gegen mehrere Krebsarten, insbesondere Hirntumore, wirksam sein soll. Empfohlen wird die Diät zusammen mit einer Standard-Chemotherapie.

Methionin ist eine Aminosäure, gehört also zu den Proteinen. Große Mengen davon sind vor allem in tierischen Proteinen enthalten, also Fleisch, Milch, Käse, Fisch, Eier usw.

Ich halte es schon für möglich, dass etwas dran ist, insbesondere, da viele Langzeitüberlebende Fleisch meiden.

Was mir nicht gefällt ist, dass das Ergebnis vieler vorhergehender Studien nicht berücksichtigt ist: Nämlich dass die Gesamtkalorienmenge pro Tag und der damit verbundene hohe bzw. niedrige Glukosespiegel einen Einfluss auf das Tumorwachstum haben (siehe selber Link).

Ich vermute, wir werden davon noch mehr hören.

Neue Studie soll die Auswirkung von Aminosäuren auf Gehirntumore testen

CHICAGO, February 23, 2004. Die CRTF Krebsforschungsstiftung hat heute angekündigt, eine 2-Jahres-Studie zu finanzieren, die untersuchen soll, ob das Weglassen der Aminosäure Methionin in der Nahrung zusammen mit Chemotherapie die Überlebensrate und Lebensqualität für Patienten mit Glioblastoma multiforme (GBM) erhöht. Glioblastoma multiforme ist eine verbreitete und tödliche Form von Gehirntumor.

Morris D. Groves, Arzt und Lehrbeauftragter im Fach Neuroonkologie, am MD Anderson Krebszentrum der Universität Texas wird die Studie durchführen. Sie sieht eine Behandlung mit einer Standard-Chemotherapie vor, kombiniert mit einer speziellen methioninfreien Diät. Schon die Diät alleine sollte einige Tumorzellen sterben lassen, aber zusammen mit der Chemotherapie erwartet Dr. Groves einen starken Anti-Tumor-Effekt.

"Die Diät funktioniert auf vielfältige und komplexe Art und Weise, aber im wesentlichen schaltet sie Gene ein, die dabei helfen, Krebs zu bekämpfen oder Widerstand zu leisten, und sie schaltet Gene ab, die Krebszellen, der Standardtherapie zu widerstehen", erklärt Dr. Groves.

Um Methionin aus der Diät zu eliminieren, müssen die Patienten das Protein in ihrer Nahrung durch die Nahrungsergänzung Hominex-2® ersetzen.
[...]

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New Study to Probe Effects of Amino Acid on Brain Cancer

Cancer Treatment Research Foundation announced today that it is funding a two-year study investigating whether the elimination of the amino acid methionine from the diet, coupled with chemotherapy, provides increased survival and quality of life enhancement for patients suffering from glioblastoma multiforme (GBM), a common and deadly type of brain cancer.

Morris D. Groves, MD, Assistant Professor of Neuro Oncology at MD Anderson Cancer Center at the University of Texas, will conduct the study, which will treat patients with standard chemotherapy combined with a special methionine-free diet. The diet alone should cause some tumor cells to die, but combined with chemotherapy, Dr. Groves anticipates a powerful anti-tumor effect.

"The diet works in many complex ways, but broadly, it turns "on" genes that help us fight or resist cancer and turns "off" genes that help cancer cells resist standard therapy", noted Dr. Groves.

In order to remove methionine from the diet, patients will need to replace the protein in their diet with the supplement shake Hominex-2®. As long as the therapy is working and the side effects are limited, the therapy will be continued for up to one year in each patient. In addition to preventing tumor growth, this therapy is expected to improve patients' quality of life by giving them a feeling of control that comes from taking proactive steps to combat their disease.

GBM is a serious and deadly form of brain cancer with an average length of survival after diagnosis of one year. As a result, any extension of life for GBM patients is significant.

"Methionine restriction has the potential to be a breakthrough therapy. If proven beneficial, this treatment can easily be expanded to other cancer types and combined with other chemotherapies. This is exactly the type of innovative, high-impact research Cancer Treatment Research Foundation is privileged to fund", said Kristine Nelson, MD, Vice President of Research for CTRF.

As with all studies funded by CTRF, Dr. Groves' proposal went through a rigorous evaluation by the Foundation's Board of Scientific Counselors. This group of world-renowned scientists ensures that all prospective projects meet the highest standards of scientific merit and proper methodology, and that the studies are in line with CTRF's mission of funding research that will make an immediate difference in the lives of cancer patients - CTRF does not fund any research on animals or basic science at the test-tube level.

CHICAGO, February 23, 2004 – CTRF
Quelle: http://www.ctrf.org/news.cfm#brain

Johanna Teig:
http://clincancerres.aacrjournals.org/cgi/content/abstract/6/2/643

Experimental Therapeutics, Preclinical Pharmacology

Methionine Depletion Enhances the Antitumoral Efficacy of Cytotoxic Agents in Drug-resistant Human Tumor Xenografts1
F. Poirson-Bichat, R. A. Bras Gonçalves, L. Miccoli, B. Dutrillaux and M. F. Poupon2
Institut Curie, UMR 147 CNRS-Institut Curie, 75231 Paris Cedex 05, France

Efficacy of chemotherapy is limited in numerous tumors by specific cellular mechanisms that inactivate cytotoxic antitumoral drugs, such as ATP-dependent drug efflux and/or drug detoxification by glutathione. In reducing ATP pools and/or glutathione synthesis, it might be possible to enhance the efficacy of drugs affected by such resistance mechanisms. Reduction of the ATP pool and glutathione content is achievable in cancer cells by depleting the exogenous methionine (Met) supply and ethionine. Thus, the rationale for the present study was to use Met depletion to decrease the ATP and glutathione pools so as to sensitize tumors refractory to cytotoxic anticancer drugs. Met depletion was achieved by feeding mice a methionine-free diet supplemented with homocysteine. The effects of Met depletion combined with ethionine and/or chemotherapeutic agents were studied using human solid cancers xenografted into nude mice. TC71-MA (a colon cancer) SCLC6 (a small cell lung cancer), and SNB19 (a glioma) were found to be refractory to cisplatin, doxorubicin, and carmustine, respectively. These three drugs are used to treat such tumors and are dependent for their activity on the lack of cellular ATP- or glutathione-dependent mechanisms of resistance. TC71-MA, SCLC6, and SNB19 were Met dependent because their proliferation in vitro and growth in vivo were reduced by Met depletion. Cisplatin was inactive in the treatment of TC71-MA colon cancer, whereas a methionine-free diet, alone or in combination with ethionine, prolonged the survival of mice by 2-fold and 2.8-fold, respectively. When all three approaches were combined, survival was prolonged by 3.3-fold. Doxorubicin did not affect the growth of SCLC6, a MDR1-MRP-expressing tumor. A Met-deprived diet and ethionine slightly decreased SCLC6 growth and, in combination with doxorubicin, an inhibition of 51% was obtained, with survival prolonged by 1.7-fold. Combined treatment produced greater tumor growth inhibition (74%) in SCLC6-Dox, a SCLC6 tumor pretreated with doxorubicin. Growth of SNB19 glioma was not inhibited by carmustine, but when it was combined with Met depletion, survival duration was prolonged by 2-fold, with a growth inhibition of 80%. These results indicate the potential of Met depletion to enhance the antitumoral effects of chemotherapeutic agents on drug-refractory tumors.

Johanna Teig:
Ein weiterer Artikel über Methionin-arme Diät, diesmal nicht speziell über Hirntumore:


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Can Dietary Methionine Restriction Increase the Effectiveness of Chemotherapy in Treatment of Advanced Cancer?
Daniel E. Epner, MD
Baylor College of Medicine, Houston, Texas

Address correspondence to: Daniel E. Epner, MD, FACP, VA Medical Center, Medical Service (111H), 2002 Holcombe Blvd, Houston, TX 77030. E-mail: depner@bcm.tmc.edu

Most metastatic tumors, such as those originating in the prostate, lung, and gastrointestinal tract, respond poorly to conventional chemotherapy. Novel treatment strategies for advanced cancer are therefore desperately needed. Dietary restriction of the essential amino acid methionine offers promise as such a strategy, either alone or in combination with chemotherapy or other treatments. Numerous in vitro and animal studies demonstrate the effectiveness of dietary methionine restriction in inhibiting growth and eventually causing death of cancer cells. In contrast, normal host tissues are relatively resistant to methionine restriction. These preclinical observations led to a phase I clinical trial of dietary methionine restriction for adults with advanced cancer. Preliminary findings from this trial indicate that dietary methionine restriction is safe and feasible for the treatment of patients with advanced cancer. In addition, the trial has yielded some preliminary evidence of antitumor activity. One patient with hormone-independent prostate cancer experienced a 25% reduction in serum prostate-specific antigen (PSA) after 12 weeks on the diet, and a second patient with renal cell cancer experienced an objective radiographic response. The possibility that methionine restriction may act synergistically with other cancer treatments such as chemotherapy is being explored. Findings to date support further investigation of dietary methionine restriction as a novel treatment strategy for advanced cancer.

Key words: methionine restriction, cancer treatment, chemotherapy, synergism
Quelle: http://www.jacn.org/cgi/content/abstract/20/suppl_5/443S

Ulrich:
Methionin ist eine essentielle Aminosäure, die der Körper braucht, aber nicht selbst herstellen kann. Wurde das berücksichtigt, oder läuft das unter "Nebenwirkungen"?

Ich kann aber auf die Schnelle nicht sagen, was passiert, wenn Methionin fehlt.

Die Aminosäure wirkt als Alkylierungsreagenz, überträgt eine Methylgruppe.

Weltegast:
Man müsste schon etwas mehr wissen. Zum Beispiel, was gegessen werden darf/soll. Methionin ist z. B. in folgenden Lebensmitteln enthalten:

Fisch (Lachs,Garnelen), Fleisch und Gemüsen ( Brokkoli, grüne Erbsen, Rosenkohl, Spinat), Ei, Vollkornbrot und Reis.

Als Ersatz für das Methionin schlägt die Studie Hominex-2 http://rpdcon40.ross.com/pn/PediatricProducts.NSF/0/7A37B0C0DCED38F585256A80007546EB?OpenDocument vor.

Es wäre interessant zu erfahren, wie eine Diät dann aussehen müsste, denn Fisch, Vollkornbrot und Gemüse sind ja Eckpfeiler der Ernährung mit niedrigem glykämischem Index.

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