Three-dimensional and co-culture models for preclinical evaluation of metal-based anticancer drugs.

BACKGROUND: Hypoxic and necrotic regions that accrue within solid tumors in vivo are known to be associated with metastasis formation, radio- and chemotherapy resistance, and drug metabolism. Therefore, integration of these tumor characteristics into in vitro drug screening models is advantageous for any reliable investigation of the anticancer activity of novel drug candidates. In general, usage of cell culture models with in vivo like characteristics has become essential in preclinical drug studies and allows evaluation of complex problems such as tumor selectivity and anti-invasive properties of the drug candidates. MATERIALS AND METHODS: In this study, we investigated the anticancer activity of clinically approved, investigational and experimental drugs based on platinum (cisplatin, oxaliplatin and KP1537), gallium (KP46), ruthenium (KP1339) and lanthanum (KP772) in different cell culture models such as monolayers, multicellular spheroids, as well as invasion and metastasis models. Results Application of the Alamar Blue assay to multicellular spheroids and a spheroid-based invasion assay resulted in an altered rating of compounds with regard to their cytotoxicity and ability to inhibit invasion when compared with monolayer-based cytotoxicity and transwell assays. For example, the gallium-based drug candidate KP46 showed in spheroid cultures significantly enhanced properties to inhibit protrusion formation and fibroblast mediated invasiveness, and improved cancer cell selectivity. CONCLUSION: Taken together, our results demonstrate the advantages of spheroid-based assays and underline the necessity of using different experimental models for reliable preclinical investigations assessing and better predicting the anticancer potential of new compounds.

Technical note: A novel method for gentle and non-destructive removal of flesh from bones.

For bone preparation, several maceration techniques are available; however, gentle defleshing and soft tissue removal from bones without damaging the bone surface remains a challenge. The study aims to develop a novel, inexpensive, rapid, and resource-saving maceration technique that does not lead to bone surface changes and allows the study of signs of violence on the bone surface. Pig ribs and femurs were covered in aluminum foil and treated in the oven for 5 h at different temperatures with and without detergent. Additionally, femurs were placed in hot non-boiling water containing household bleach and detergents for 1 h. Examinations using macro photography, stereo and fluorescence microscopy, and micro-computed tomography showed no surface changes after treatment at 100 °C, such as flakes or bone cracks, on the ribs. The femurs showed surface changes after incubation in water, such as roughening.

Behavior of platinum(iv) complexes in models of tumor hypoxia: cytotoxicity, compound distribution and accumulation.

Hypoxia in solid tumors remains a challenge for conventional cancer therapeutics. As a source for resistance, metastasis development and drug bioprocessing, it influences treatment results and disease outcome. Bioreductive platinum(iv) prodrugs might be advantageous over conventional metal-based therapeutics, as biotransformation in a reductive milieu, such as under hypoxia, is required for drug activation. This study deals with a two-step screening of experimental platinum(iv) prodrugs with different rates of reduction and lipophilicity with the aim of identifying the most appropriate compounds for further investigations. In the first step, the cytotoxicity of all compounds was compared in hypoxic multicellular spheroids and monolayer culture using a set of cancer cell lines with different sensitivities to platinum(ii) compounds. Secondly, two selected compounds were tested in hypoxic xenografts in SCID mouse models in comparison to satraplatin, and, additionally, (LA)-ICP-MS-based accumulation and distribution studies were performed for these compounds in hypoxic spheroids and xenografts. Our findings suggest that, while cellular uptake and cytotoxicity strongly correlate with lipophilicity, cytotoxicity under hypoxia compared to non-hypoxic conditions and antitumor activity of platinum(iv) prodrugs are dependent on their rate of reduction.

Preparation and characterization of immobilized [A336][MTBA] in PVA-alginate gel beads as novel solid-phase extractants for an efficient recovery of Hg (II) from aqueous solutions.

The coarse PVA-alginate matrix gel beads entrapping the micro-droplets of the ionic liquid tricaprylylmethylammonium 2-(methylthio) benzoate ([A336][MTBA]) as novel solid-phase extractants were prepared for the removal of mercury (II) from aqueous media. The ionic liquid [A336][MTBA] immobilized PVA-alginate beads (PVA/IL) have been characterized by FTIR, SEM and TGA. The influence of the uptake conditions was investigated including aqueous pH, PVA/IL dosage, the content of [A336][MTBA] and initial Hg (II) concentration; maximum Hg (II) ion adsorption capacity obtained was 49.89 (± 0.11)mgg(-1) at pH 5.8 with adsorptive removal of approximately 99.98%. The selectivity of the PVA/IL beads towards Hg (II), Pb (II) and Cu (II) ions tested was Hg>Pb>Cu. The rate kinetic study was found to follow second-order and the applicability of Langmuir, Freundlich and Tempkin adsorption isotherm model were tested as well. The results of the study showed that PVA/IL beads could be efficiently used as novel extractants for the removal of divalent mercury from aqueous solutions under comparatively easy operation conditions.