Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glioblastoma is a therapeutic challenge as a highly infiltrative, proliferative, and resistant tumor. Among novel therapeutic approaches, proteasome inhibition is very promising in controlling cell cycle and inducing apoptosis. This study investigated the effect of ritonavir, a protease inhibitor of the HIV and a proteasome modulator, on glioma cells. The hypothesis was that proteasome modulation, mainly by only inhibiting proteasome chymotrypsin-like activity, could be sufficient to control tumor progression. The experiments were done on a human glioblastoma-derived GL15 cell line and a rat nitrosourea-induced gliosarcoma 9L cell line. Culturing conditions included monolayer cultures, transplantations into brain slices, and transplantations into rat striata. The study demonstrates that ritonavir, by inhibiting the chymotrypsin-like activity of the proteasome, has cytostatic and cytotoxic effects on glioma cells, and can induce resistances in vitro. Ritonavir was unable to control tumor growth in vivo, likely because the therapeutic dose was not reached in the tumor in vivo. Nevertheless, ritonavir might also be beneficial, by decreasing tumor infiltration, in the reduction of the deleterious peritumor edema in glioblastoma.
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PMID:Effects of the proteasome inhibitor ritonavir on glioma growth in vitro and in vivo. 1498 53

Lactacystin, a proteasome-inhibitor, has been shown to induce apoptosis of experimental gliomas in vitro. However, its systemic toxicity prevents further clinical use. To circumvent this problem, lactacystin can be delivered intratumorally. We tested the efficacy of lactacystin incorporated into controlled-release polymers for treating experimental gliomas. 9L-gliosarcoma and F98-glioma cell lines were treated with lactacystin (10-100 microg/ml) for 72 h in vitro. Cell-viability was measured with MTT-assays. Toxicity of lactacystin/polycarboxyphenoxypropane-sebacic-acid (pCPP : SA) polymers was tested in vivo using Fischer-344 rats intracranially implanted with lactacystin polymers loaded from 0.1 to 2% lactacystin by weight. The efficacy of 1, 1.3, 1.5 and 1.7% lactacystin/pCPP : SA polymers was determined in Fischer-344 rats intracranially challenged with 9L and treated either simultaneously or 5 days after tumor implantation. Lactacystin was cytotoxic in 9L cells, causing a 16 +/- 8% growth inhibition at 10-microg/ml that increased to 78 +/- 4% at 100-microg/ml. Similarly, lactacystin inhibited growth of F98 by 18 +/- 8% at 10-microg/ml and 74 +/- 2% at 100-microg/ml in vitro. Polymers released lactacystin for 21 days and intracranial implantation in rats neither generate local nor systemic toxicity at doses lower than 2%. Treatment with lactacystin/pCPP : SA polymers with loading concentrations of 1.0, 1.3, and 1.5% prolonged survival of animals intracranially challenged with 9L when polymers where inserted in the day of tumor implantation. In conclusion, lactacystin exhibits potent cytotoxic-activity against 9L and F98 in vitro, it can be efficiently incorporated and delivered using controlled-release polymers, and at the proposed concentrations lactacystin polymers are safe for CNS delivery and prolong survival in the 9L model.
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PMID:Lactacystin exhibits potent anti-tumor activity in an animal model of malignant glioma when administered via controlled-release polymers. 1660 37