Continuous administration of the somatostatin structural derivative /TT-232/ by subcutaneously implanted osmotic pump improves the efficacy and potency of antitumor therapy in different mouse and human tumor models.
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BACKGROUND: The somatostatin structural derivative, TT-232, has a special 5-residue ring structure (D-Phe-Cys-Tyr-D-Trp-Lys-Cys-Thr-NH2) and very different characteristics from the known growth hormone (GH) active somatostatin analogs. This somatostatin structural derivative has no GH release inhibitory or antisecretory activity and does not bind to rat pituitary or the cortex, where all the known somatostatin receptor subtypes are expressed. TT-232 had previously been shown to inhibit the proliferation of a large number of cancer cell lines in vitro and reduce the size of different tumors in animal models in vivo. MATERIALS AND METHODS: The therapeutic efficacy of TT-232 was evaluated in different long-term administration routes: the traditional injection (i.p. or s.c.) versus infusion treatment via s.c.- or i.v.-inserted Alzet osmotic minipump, and on different types of transplantable rodent (S-180 sarcoma, P-388sc lymphoid leukemia, Colon-26 adenocarcinoma, MXT breast carcinoma, B-16 melanoma) and human tumor models (HT-18 lymphoid melanoma, T-47/D breast carcinoma, A-431 epidermoid carcinoma). On the basis of our previous experiments the optimum injected dose of TT-232 was found to be 15 microg/kg twice a day. This dose is equivalent to 0.6 dg/day by infusion therapy. RESULTS: In our experiments, the best results were achieved when TT-232 was applied as an infused treatment. In the S-180 sarcoma and P-388sc lymphoid leukemia rodent tumor models the infusion treatment with TT-232 resulted in 61%-100% tumor growth inhibition and in 20%-60% of the mice being long-term and tumor-free survivors. In the aggressive Colon-26 adenocarcinoma and MXT breast carcinoma models, the infusion treatment resulted in 52%-75% tumor growth inhibition. In the B-16 melanoma model, the infusion treatments resulted in 47% -63% growth inhibition. The tumor growth inhibitory effect of infusion treatment with TT-232 on HT-18 human lymphoid melanoma tumor proved to be significant, resulting in 69%-79% decreases in tumor volume. In the T-47/D human breast carcinoma, the infusion treatment resulted in 48%-53% tumor growth inhibition. The tumor growth inhibitory effect of infusion treatment on A-431 human epidermoid carcinoma tumor resulted in 70%-74% decreases in tumor volume. CONCLUSION: The antitumor efficacy of TT-232 was seen in almost all the tumors investigated. In our study, the route of infusion was shown to increase drug efficacy relative to conventional delivery methods (injection). The results obtained from this study suggest that TT-232 is a promising new antitumor agent in cancer chemotherapy and a good candidate for delivery by continuous (infusion) therapy. (+info)
Behavioral effects of systemic transforming growth factor-alpha in Syrian hamsters.
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Recombinant human relaxin in the treatment of systemic sclerosis with diffuse cutaneous involvement: a randomized, double-blind, placebo-controlled trial.
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Enhancement of lung carcinogenesis initiated with 4-(N-hydroxymethylnitrosamino)-1-(3-pyridyl)-1-butanone by Ogg1 gene deficiency in female, but not male, mice.
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The present study was conducted to assess involvement of oxidative stress in lung adeno-carcinogenesis, using mice deficient in the 8-hydroxyguanine DNA glycosylase 1 (Ogg1) gene encoding an enzyme that repairs an oxidative DNA injury 8-oxoguanine (8-oxoG). Furthermore, for comparison with the human case, mutations of mouse epidermal growth factor receptor (Egfr) and K-ras genes were examined. The homo- and heterozygously Ogg1 gene-deficient and wild-type mice (C57BL6/J origin), 6 weeks old, were administered 4-(N-hydroxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) by continuous subcutaneous infusion using an osmotic pump at a total dose of 6 mg/mouse for 1 week, then treated with one of 4 antioxidants (phenyl N-tert-butyl nitrone 0.13% in drinking water, resveratrol 20 ppm in diet, lactoferrin 2% in diet and bilberry powder 2% in diet) or no supplement for 33 weeks. Development of lung adenomas and preneoplastic atypical hypreplasias was significantly enhanced by the homo- and heterozygous Ogg1 gene deficiency only in female mice with intralesion accumulation of 8-oxoG. All antioxidants tended to inhibit enhanced adeno-carcinogenesis. The Egfr and K-ras gene mutations were detected at sites also found in human lung cancers with low incidences, while the Egfr gene mutation was detected for the first time in chemical lung carcinogenesis of animals. It is indicated that the Ogg1 gene deficiency enhances lung adeno-carcinogenesis in mice by virtue of accelerated oxidative stress. The presently utilized Ogg1 gene-deficient mice model may be useful to draw mechanism-based strategies to control human lung adenocarcinomas, especially in women. (+info)