Cytotoxic activity of a new paclitaxel formulation, Pacliex, in vitro and in vivo

Combined 4D-QSAR and target-based approaches for the determination of bioactive Isatin derivatives

The hybrid method of the Electron-Conformational Genetic Algorithm (EC-GA) was used to determine the pharmacophore groups and to estimate anticancer activity in isatin derivatives using a robust 4D-QSAR software (EMRE). To build the model, each compound is represented by a set of conformers rather than a single conformation. The Electron Conformational Matrix of Congruity (ECMC) is composed via EMRE software. Electron Conformational Submatrix of Activity (ECSA) was calculated by the comparison of these matrices. Genetic algorithm was used to select important variables to predict theoretical activity. The model with the best seven parameters produced satisfactory results. The E statistics technique was applied to the generated EC-GA model to evaluate the individual contribution of each of the descriptors on biological activity. The r² and q² values of the training set compounds were found to be 0.95 and 0.93, respectively. Because no previous 4D-QSAR studies on isatin derivatives have been conducted, this study is important in the development of new isatin derivatives. In this study, 27 isatin derivatives whose activities were estimated using the hybrid EC-GA method were also investigated through molecular docking and molecular dynamics simulations for their BCL-2 inhibitory activity.

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Synthesis and evaluation of N-(4-(substituted)-3-(trifluoromethyl) phenyl) isobutyramides and their N-ethyl analogous as anticancer, anti-angiogenic & antioxidant agents: In vitro and in silico analysis

N-(4-(substituted)-3-(trifluoromethyl) phenyl) isobutyramides and their N-ethyl analogues (flutamides) are versatile scaffolds with a wide spectrum of biological activities. A series of new N-(4-(substituted)-3-(trifluoromethyl) phenyl) isobutyramides (8a-t) and their N-ethyl analogous (9a-t) were synthesized and characterized. The inhibitory potential of the synthesized compounds on the viability of three human cancer cell lines HEP3BPN 11 (liver), MDA-MB 453 (breast), and HL 60 (leukemia) were assessed. Among all the compounds 8 L, 8q, 9n and 9p showed higher inhibitory activity on the viability of HL 60 than the standard methotrexate. These lead molecules were then tested for their potential to inhibit the activity of proangiogenic cytokines. The compound 9n showed significantly better inhibition against two cytokines viz. TNFα and Leptin as compared to the standard suramin, while 9p has activity comparable to suramin against IGF1, VEGF, FGFb, and Leptin. The 8q is found to be strong antiangiogenic agent against IGF1, VEGF and TGFβ; while 8 L has showed activity against TNFα, VEGF, and Leptin inhibition. Furthermore antioxidant potential of 8a-t and 9a-t compounds was screened using DPPH, OH and SOR radical scavenging activities. The OH radical scavenging activity of 8c and DPPH activities of 9n as well as 9o are significant as compared to respective standards ascorbic acid and α-tocopherol. The 8c, 9p and 9 h have also exhibited potential antioxidant activity. Additionally, we present in silico molecular docking data to provide the structural rationale of observed TNFα inhibition against newly synthesized compounds. Overall, the synthesized flutamide derivatives have not only anticancer activity, but also possess dual inhibitory effect (anti-angiogenesis and antioxidant) and hence can act as a promising avenue to develop further anticancer agents.

A novel hybrid method named electron conformational genetic algorithm as a 4D QSAR investigation to calculate the biological activity of the tetrahydrodibenzazosines

To understand the structure-activity correlation of a group of tetrahydrodibenzazocines as inhibitors of 17β-hydroxysteroid dehydrogenase type 3, we have performed a combined genetic algorithm (GA) and four-dimensional quantitative structure-activity relationship (4D-QSAR) modeling study. The computed electronic and geometry structure descriptors were regulated as a matrix and named as electron-conformational matrix of contiguity (ECMC). A chemical property-based pharmacophore model was developed for series of tetrahydrodibenzazocines by EMRE software package. GA was employed to choose an optimal combination of parameters. A model has been developed for estimating anticancer activity quantitatively. All QSAR models were established with 40 compounds (training set), then they were considered for selective capability with additional nine compounds (test set). A statistically valid 4D-QSAR ( R training 2 = 0.856 , R test 2 = 0.851 and q² = 0.650) with good external set prediction was obtained.

In vivo model for mastocytosis: A comparative review

Human mastocytosis are heterogeneous group of neoplastic diseases characterized by a different degree of uncontrolled mast cell (MC) proliferation and activation. Interestingly, human mastocytosis share several biological and clinical features with canine mast cell disorders, so called canine mast cell tumors (CMCTs). These CMCTs are the most common spontaneous cutaneous tumors found in dogs representing a valid model to study neoplastic mast cell disorders. It has been discovered that the pathological activation of c-Kit receptor (c-KitR), expressed by MCs, has been involved in the pathogenesis of neoplastic MC disorders. In this review we have focused on human mastocytosis in terms of: (i) epidemiology and classification; (ii) pathogenesis at molecular levels; (iii) clinical presentation. In addition, we have summarized animal models useful to study neoplastic MC disorders including CMCTs and murine transgenic models. Finally, we have revised therapeutic approaches mostly common in human and canine MCTs and novel tyrosine kinase inhibitors approved for CMCTs and recently translated in human clinical trials.

Polylactide-based paclitaxel-loaded nanoparticles fabricated by dispersion polymerization: characterization, evaluation in cancer cell lines, and preliminary biodistribution studies

The macromonomer method was used to prepare cross-linked, paclitaxel-loaded polylactide (PLA)-polyethylene glycol (stealth) nanoparticles using free-radical dispersion polymerization. The method can facilitate the attachment of other molecules to the nanoparticle surface to make it multifunctional. Proton nuclear magnetic resonance and Fourier transform infrared spectra confirm the synthesis of PLA macromonomer and cross-linking agent. The formation of stealth nanoparticles was confirmed by scanning and transmission electron microscopy. The drug release isotherm of paclitaxel-loaded nanoparticles shows that the encapsulated drug is released over 7 days. In vitro cytotoxicity assay in selected breast and ovarian cancer cell lines reveal that the blank nanoparticle is biocompatible compared with medium-only treated controls. In addition, the paclitaxel-loaded nanoparticles exhibit similar cytotoxicity compared with paclitaxel in solution. Confocal microscopy reveals that the nanoparticles are internalized by MCF-7 breast cancer cells within 1 h. Preliminary biodistribution studies also show nanoparticle accumulation in tumor xenograft model. The nanoparticles are suitable for the controlled delivery of bioactive agents.

Anti-tumor pharmacological evaluation of extracts from stellera chamaejasme L based on hollow fiber assay

BACKGROUND

Stellera chamaejasme L, a traditional Chinese herb, has long been used for treatment of various tumors in the Chinese population. In our previous study, we paid an attention to the cytotoxic and proapoptotic effects of Stellera chamaejasme L extracts (ESC, ESC-1 and ESC-2, the latter two were isolated from ESC) on 4 various tumor cells (NCI-H157, NCI-H460, BEL-7402 and SK-HEP-1) in vitro. ESCs showed significantly inhibitory effects on the 4 tumor cells. ESC-2 had the strongest inhibitory effect and the broadest sensitive cell spectrum. ESC-2 and ESC acted in a similar way against tumor cells, which suggested anti-tumor active fraction of ESC might exist in ESC-2. Here, we further observe the inhibitory and proapoptotic effects of Stellera chamaejasme L extracts in vivo.

METHODS

In this study, we used hollow fiber tumor model to evaluate the inhibitory and proapoptotic effects of Stellera chamaejasme L extracts. Apoptotic rates of the cancer cells retrieved from the hollow fibers were measured with flow cytometric analysis, caspase 3, 8, 9 enzyme activities were detected by colorimetric assay, Fas, Fas-L, TNF-R1 and TNF-α expression were determined with elisa assay and radioimmunoassay respectively.

RESULTS

The results showed that ESC, ESC-2 all had inhibitory effects on 4 tumor cells. According to the effect strength, dose and antitumor spectrum, the order of antitumor effects of ESCs was: ESC-2 > ESC > ESC-1. NCI-H460 cells were the most sensitive to ESCs. ESC, ESC-2 increased greatly the apoptotic rate and caspase 3, 8 enzyme activities in NCI-H460. ESCs had no significant effects on expression of Fas, Fas-L protein, but TNF-α/TNFR1 protein expression in NCI-H460 cells changed significantly after ESC and ESC-2 treatment.

CONCLUSION

ESC-2 had the similar antitumor effect to that of ESC in vivo and further confirmed that ESC-2 may be the main antitumor active fraction of ESC, which was consistent with our previous results in vitro.

Clinical efficacy and safety of a water-soluble micellar paclitaxel (Paccal Vet) in canine mastocytomas

OBJECTIVE

To determine the clinical efficacy and safety of a cremophor-free formulation of paclitaxel (Paccal Vet, Oasmia Pharmaceuticals) in dogs with mast cell tumours.

METHODS

Paccal Vet was administered at a median dose of 145 (range, 135 to 150) mg/m(2) intravenously once every 21 days for three cycles to 29 dogs with macroscopic grade 2 or 3 mast cell tumour. Efficacy was assessed by tumour response (Response Evaluation Criteria in Solid Tumours version 1.0) and performance status score. Progression-free survival, quality of life and safety/adverse events were also evaluated. Clinical safety was assessed by clinicopathological analyses and recording of adverse events.

RESULTS

Complete or partial response was observed in 59% of dogs. Performance status score remained constant or improved for 20 dogs and decreased by one grade for 9 dogs. Median time to progression was 247 (range, 42 to 268) days. Expected, transient frequently subclinical adverse events (primarily grade 3/4 neutropenia and grade 1/2 leukopenia) were observed in the majority of dogs. Nine dogs were euthanased and one dog died due to disease progression.

CLINICAL SIGNIFICANCE

Paccal Vet appears to be a clinically safe and effective treatment for canine mast cell tumours. Further controlled confirmatory investigation is warranted.

A dose-finding study with a novel water-soluble formulation of paclitaxel for the treatment of malignant high-grade solid tumours in dogs

A new formulation of water-soluble paclitaxel (Paccal® Vet) has been developed for canine cancer patients, without the need for pre-medication (traditionally required in non-water-soluble paclitaxel formulations). The objective of the study was to determine a clinically safe and efficacious dose of Paccal Vet and to estimate progression-free and overall survival and to evaluate single-dose pharmacokinetics in tumour-bearing dogs. A positive risk:benefit ratio was established for Paccal Vet administered at 150 mg m(-2) intravenous (IV) for three or more treatment cycles. Preliminary efficacy was demonstrated by best objective response rate (86%), median time to response (14 days) and median progression-free survival (131 days). Paccal Vet was associated with expected adverse events (AE) (e.g. myelosuppression), however the majority were transient, clinically silent and manageable. This is the first clinical report of a water-soluble formulation of paclitaxel suggesting successful administration and being safely used without pre-medication in dogs.

Evaluation of toxicity and antitumor activity of cycloviolacin O2 in mice

Cycloviolacin O2 is a small cyclic cysteine-rich protein belonging to the group of plant proteins called cyclotides. This cyclotide has been previously shown to exert cytotoxic activity against a variety of human tumor cell lines as well as primary cultures of human tumor cells in vitro. This study is the first evaluation of its tolerability and antitumor activity in vivo. Maximal-tolerated doses were estimated to 1.5 mg/kg for single intravenous (i.v.) dosing and 0.5 mg/kg for daily repeated dosing, respectively. Two different in vivo methods were used: the hollow fiber method with single dosing (i.v., 1.0 mg/kg) and traditional xenografts with repeated dosing over 2 weeks (i.v., 0.5 mg/kg daily, 5 days a week). The human tumor cell lines used displayed dose-dependent in vitro sensitivity (including growth in hollow fibers to confirm passage of cycloviolacin O2 through the polyvinylidene fluoride fibers), with IC5o values in the micromolar range. Despite this sensitivity in vitro, no significant antitumor effects were detected in vivo, neither with single dosing in the hollow fiber method nor with repeated dosing in xenografts. In summary, the results indicate that antitumor effects are minor or absent at tolerable (sublethal) doses, and cycloviolacin O2 has a very abrupt in vivo toxicity profile, with lethality after single injection at 2 mg/kg, but no signs of discomfort to the animals at 1.5 mg/kg. Repeated dosing of 1 mg/kg gave a local-inflammatory reaction at the site of injection after 2-3 days; lower doses were without complications.

Development of new lipid-based paclitaxel nanoparticles using sequential simplex optimization

The objective of these studies was to develop Cremophor-free lipid-based paclitaxel (PX) nanoparticle formulations prepared from warm microemulsion precursors. To identify and optimize new nanoparticles, experimental design was performed combining Taguchi array and sequential simplex optimization. The combination of Taguchi array and sequential simplex optimization efficiently directed the design of paclitaxel nanoparticles. Two optimized paclitaxel nanoparticles (NPs) were obtained: G78 NPs composed of glyceryl tridodecanoate (GT) and polyoxyethylene 20-stearyl ether (Brij 78), and BTM NPs composed of Miglyol 812, Brij 78, and d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS). Both nanoparticles successfully entrapped paclitaxel at a final concentration of 150 microg/ml (over 6% drug loading) with particle sizes less than 200 nm and over 85% of entrapment efficiency. These novel paclitaxel nanoparticles were stable at 4 degrees C over five months and in PBS at 37 degrees C over 102 h as measured by physical stability. Release of paclitaxel was slow and sustained without initial burst release. Cytotoxicity studies in MDA-MB-231 cancer cells showed that both nanoparticles have similar anticancer activities compared to Taxol. Interestingly, PX BTM nanocapsules could be lyophilized without cryoprotectants. The lyophilized powder comprised only of PX BTM NPs in water could be rapidly rehydrated with a complete retention of original physicochemical properties, in vitro release properties, and cytotoxicity profile. Sequential Simplex Optimization has been utilized to identify promising new lipid-based paclitaxel nanoparticles having useful attributes.

p53 is involved in clearance of ionizing radiation-induced RAD51 foci in a human colon cancer cell line

We have investigated p53-related differences in cellular response to DNA damaging agents, focusing on p53s effects on RAD51 protein level and sub-cellular localization post exposure to ionizing radiation. In a human colon cancer cell line, HCT116 and its isogenic p53-/- subcell line we show here p53-independent RAD51 foci formation but interestingly the resolution of RAD51 foci showed clear p53 dependence. In p53 wt cells, but not in p53-/- cells, RAD51 protein level decreased 48 h post irradiation and fluorescence immunostaining showed resolution of RAD51 foci and relocalization of RAD51 to nucleoli at time points corresponding to the decrease in RAD51 protein level. Both cell lines rejoined DNA double strand breaks efficiently with similar kinetics and p53 status did not influence sensitivity to DNA damaging agents. We suggest that p53 has a role in RAD51 clearance post DSB repair and that nucleoli might be sites of RAD51 protein degradation.