Enhancement of in vivo antitumor activity of classical anticancer agents by combination with the new, glutathione-interacting DNA minor groove-binder, brostallicin.

PURPOSE: Brostallicin (PNU-166196) is a alpha-bromoacrylic DNA minor groove binder, currently in clinical evaluation. This drug has the peculiarity of showing enhanced antitumor activity in cells with high glutathione S-transferase (GST)/glutathione content. The purpose of the study was to study multiple combinations of brostallicin with classical anticancer agents. EXPERIMENTAL DESIGN: The cis-dichloro-diammine-platinum (cDDP)/brostallicin combination was tested in the human colon carcinoma (HCT-116) model transplanted in nude mice. Two treatment schedules were tested: cDDP followed by brostallicin 48 h after or brostallicin followed by cDDP. These two schemes were selected from the observation that tumor cells in vitro show an increased activity of GST 48 h after cDDP treatment. The HCT-116 model was used also to test the irinotecan (cPT-11)/brostallicin combination. The effect of brostallicin in combination with doxorubicin (DX) was studied in the i.v. injected murine L1210 leukemia. Three administration schedules were tested. The antitumor activity of brostallicin and Taxotere was tested on the A549 lung cancer xenografts. RESULTS: In line with the increased GST activity observed after treatment with cDDP, the cDDP/brostallicin interaction was sequence-dependent, leading to a more than additive antitumor effect, without additional toxicity, only when cDDP was given before brostallicin. The antitumor effect of CPT-11 was enhanced significantly by brostallicin cotreatment. A more than additive antitumor effect, without additional toxicity, was observed when DX/brostallicin were sequentially administered in L1210-bearing mice. Finally, additivity was observed when brostallicin/Taxotere simultaneous combination was tested. CONCLUSIONS: Although the precise molecular mechanism of interaction between brostallicin and the other tested cytotoxics has not yet been identified, a clear therapeutic gain is observed in preclinical models when brostallicin is combined with anticancer agents such as cDDP, DX, CPT-11, and Taxotere. These results indicate the potential therapeutic value of brostallicin in cancer combination treatment therapy.     

Death and neuroprotection of retinal ganglion cells after different types of injury

In adult Sprague-Dawley rats, retinal ganglion cell survival was investigated after intraorbital optic nerve section and after transient ischemia of the retina induced by elevation of the intraocular pressure or by selective ligature of the ophthalmic vessels. The thickness of the inner nuclear and inner plexiform layers was also assessed after transient periods (120 min) of retinal ischemia induced by selective ligature of the ophthalmic vessels. In addition, we have also investigated the neuroprotective effects of different substances in these paradigms. The intraocular injection of brain-derived neurotrophic factor increased RGC survival after retinal ischemia induced by elevation of the intraocular pressure or by selective ligature of the ophthalmic vessels. The caspase-inhibitor Z-DEVD increased retinal ganglion cell survival after optic nerve section and also after 90 min of retinal ischemia induced by selective ligature of the ophthalmic vessels. The peptide Bcl-2 did not increase retinal ganglion cell survival after optic nerve section but increased retinal ganglion cell survival after 60 or 90 min of retinal ischemia induced by selective ligature of the ophthalmic vessels. Finally, BDNF, nifedipine, naloxone and bcl-2 prevented in part the decrease in thickness of the inner nuclear layer and inner plexiform layer induced by selective ligature of the ophthalmic vessels. Our results suggest that retinal ganglion cell loss induced by different types of injury, may be prevented by substances with neuroprotective effects, by altering steps of the cascade of events leading to cell death.     

Structural and biological characterization of three novel mastoparan peptides from the venom of the neotropical social wasp Protopolybia exigua (Saussure).

The venom of the Neotropical social wasp Protopolybia exigua(Saussure) was fractionated by RP-HPLC resulting in the elution of 20 fractions. The homogeneity of the preparations were checked out by using ESI-MS analysis and the fractions 15, 17 and 19 (eluted at the most hydrophobic conditions) were enough pure to be sequenced by Edman degradation chemistry, resulting in the following sequences: Protopolybia MPI I-N-W-L-K-L-G-K-K-V-S-A-I-L-NH2 Protopolybia-MP II I-N-W-K-A-I-I-E-A-A-K-Q-A-L-NH2 Protopolybia-MP III I-N-W-L-K-L-G-K-A-V-I-D-A-L-NH2 All the peptides were manually synthesized on-solid phase and functionally characterized. Protopolybia-MP I is a hemolytic mastoparan, probably acting on mast cells by assembling in plasma membrane, resulting in pore formation; meanwhile, the peptides Protopolybia-MP II and -MP III were characterized as a non-hemolytic mast cell degranulator toxins, which apparently act by virtue of their binding to G-protein receptor, activating the mast cell degranulation.     

Enoxaparin for the prevention of venous thromboembolism associated with central vein catheter: a double-blind, placebo-controlled, randomized study in cancer patients.

PURPOSE: The extent of venous thromboembolism (VTE) associated with central vein catheters (CVC) in cancer patients remains unclear. The aim of this study was to evaluate the efficacy and safety of the low molecular weight heparin, enoxaparin, in the prevention of VTE. PATIENTS AND METHODS: In a multicenter, double-blind study, consecutive cancer patients scheduled for CVC insertion were randomly assigned to receive either subcutaneous enoxaparin 40 mg once a day or placebo. Treatment was started 2 hours before CVC insertion and continued for 6 weeks. The primary end points of the study were deep vein thrombosis (DVT), confirmed by venography of the CVC limb performed 6 weeks after randomization, or clinically overt pulmonary embolism, confirmed by objective testing during the study drug administration. Patients were assessed for bleeding complications. RESULTS: Three hundred eighty-five patients were randomized, of which 321 (83.4%) underwent venography. A venography was adequate for adjudication in 155 patients in each treatment group. A DVT was observed in 22 patients (14.1%) treated with enoxaparin and in 28 patients (18.0%) treated with placebo, corresponding to a relative risk of 0.78 (95% CI, 0.47 to 1.31). No major bleeding occurred. Five patients (2.6%) in the enoxaparin group and two patients (1.0%) in the placebo group died during the treatment period. CONCLUSION: In this study, no difference in the rate of CVC-related VTE was detected between patients receiving enoxaparin and patients receiving placebo. The dose of enoxaparin used in this study proved to be safe. Clinical trials evaluating higher enoxaparin doses could optimize the efficacy of this agent for this indication.     

Long-term survival results of a randomized trial comparing gemcitabine plus cisplatin, with methotrexate, vinblastine, doxorubicin, plus cisplatin in patients with bladder cancer.

PURPOSE: To compare long-term survival in patients with locally advanced or metastatic transitional cell carcinoma (TCC) of the urothelium treated with gemcitabine/cisplatin (GC) or methotrexate/vinblastine/doxorubicin/cisplatin (MVAC). PATIENTS AND METHODS: Efficacy data from a large randomized phase III study of GC versus MVAC were updated. Time-to-event analyses were performed on the observed distributions of overall and progression-free survival. RESULTS: A total of 405 patients were randomly assigned: 203 to the GC arm and 202 to the MVAC arm. At the time of analysis, 347 patients had died (GC arm, 176 patients; MVAC arm, 171 patients). Overall survival was similar in both arms (hazard ratio [HR], 1.09; 95% CI, 0.88 to 1.34; P = .66) with a median survival of 14.0 months for GC and 15.2 months for MVAC. The 5-year overall survival rates were 13.0% and 15.3%, respectively (P = .53). The median progression-free survival was 7.7 months for GC and 8.3 months for MVAC, with an HR of 1.09. The 5-year progression-free survival rates were 9.8% and 11.3%, respectively (P = .63). Significant prognostic factors favoring overall survival included performance score (> 70), TNM staging (M0 v M1), low/normal alkaline phosphatase level, number of disease sites (相似文献   

In vitro activity of Tridax procumbens against promastigotes of Leishmania mexicana

Ethnopharmacological relevance

Tridax procumbens is an active herb against leishmaniasis.

Aim of the study

Leishmaniasis is a group of diseases caused by Leishmania protozoa. We investigated the antileishmanial activity of Tridax procumbens extracts and a pure compound against promastigotes of Leishmania mexicana, the causative agent of cutaneous leishmaniasis in the New World.

Materials and methods

Extracts and (3S)-16,17-didehydrofalcarinol (1) were obtained by chromatographic methods from Tridax procumbens, and the latter identified by spectroscopic analysis. The effect of these extracts and 1 on the growth inhibition of promastigotes of Leishmania mexicana was evaluated. In order to test the safety of extracts and 1, mammalian cells were treated with them, and cell viability was assessed using trypan blue and MTT.

Results

We demonstrated that extracts of Tridax procumbens and 1 showed a pronounced activity against Leishmania mexicana. The methanol extract inhibited promastigotes growth of Leishmania mexicana with a 50% inhibitory concentration (IC₅₀) of 3 μg/ml, while oxylipin 1 exhibited the highest inhibition at IC₅₀ = 0.478 μg/ml.

Conclusions

In this study we report the biological activity of extracts and (3S)-16,17-didehydrofalcarinol (1), obtained from Tridax procumbens, on the promastigote form of Leishmania mexicana, with no effect upon mammalian cells.