Effect of Alpha-tocopheryl Succinate on the Cytotoxicity of Anticancer Drugs Towards Leukemia Lymphocytes.

BACKGROUND/AIM: This study analysed the effect of α-tocopheryl succinate (α-TS) on the redox-state of leukemia and normal lymphocytes, as well as their sensitization to fifteen anticancer drugs. MATERIALS AND METHODS: Cell viability was analyzed by trypan blue staining and automated counting of live and dead cells. Apoptosis was analyzed by FITC-Annexin V test. Oxidative stress was evaluated by the intracellular levels of reactive oxygen species (ROS) and protein-carbonyl products. RESULTS: Most combinations (α-TS plus anticancer drug) exerted additive or antagonistic effects on the proliferation and viability of leukemia lymphocytes. α-TS combined with barasertib, bortezomib or lonafarnib showed a strong synergistic cytotoxic effect, which was best expressed in the case of barasestib. It was accompanied by impressive induction of apoptosis and increased production of ROS, but insignificant changes in protein-carbonyl levels. α-TS plus barasertib did not alter the viability and did not induce oxidative stress and apoptosis in normal lymphocytes. CONCLUSION: α-TS could be a promising adjuvant in second-line anticancer therapy, particularly in acute lymphoblastic leukemia, to reduce the therapeutic doses of barasertib, bortezomib, and lonafarnib, increasing their effectiveness and minimizing their side effects.

Pharmacological Strategy for Selective Targeting of Glioblastoma by Redox-active Combination Drug - Comparison With the Chemotherapeutic Standard-of-care Temozolomide.

BACKGROUND/AIM: We describe a pharmacological strategy for selectively targeting glioblastoma using a redox-active combination drug menadione/ascorbate (M/A), compared to the chemotherapeutic standard-of-care temozolomide (TMZ). MATERIALS AND METHODS: Experiments were conducted on glioblastoma mice (GS9L cell transplants - intracranial model), treated with M/A or TMZ. Tumor growth was monitored by magnetic resonance imaging. Effects of M/A and TMZ on cell viability and overproduction of mitochondrial superoxide were also evaluated on isolated glioblastoma cells (GS9L) and normal microglial cells (EOC2). RESULTS: M/A treatment suppressed tumor growth and increased survival without adverse drug-related side effects that were characteristic of TMZ. Survival was comparable with that of TMZ at the doses we have tested so far, although the effect of M/A on tumor growth was less pronounced than that of TMZ. M/A induced highly specific cytotoxicity accompanied by dose-dependent overproduction of mitochondrial superoxide in glioblastoma cells, but not in normal microglial cells. CONCLUSION: M/A differentiates glioblastoma cells from normal microglial cells, causing redox alterations and oxidative stress only in the tumor. This easier-to-tolerate treatment has a potential to support the surgery and conventional therapy of glioblastoma.

Loading Efficiency of Polymersomes with Contrast Agents and their Intracellular Delivery: Quantum Dots Versus Organic Dyes.

BACKGROUND/AIM: Contrast nanocarriers as drug-delivery systems, capable of selective delivery to cancer cells and solid tumors, are essential for the development of new diagnostic and therapeutic (theranostic) strategies. The present study aimed to investigate the loading efficiency of chitosan-based polymersomes with fluorescent contrast substances [quantum dots (QDs) and conventional organic dyes] and the possibility to control their release from the polymer matrix into cells by chemical modifications and electroporation. MATERIALS AND METHODS: All investigated fluorophores were retained within the polymer globule via electrostatic and hydrophilic-hydrophobic interactions, without conjugation with the polymer. The fluorophore-loaded polymersomes were characterized by dynamic light scattering, zeta-potential titration, and fluorescence spectroscopy. The release of fluorophore from the polymersomes, passively or after electroporation, was detected by 5-step spin-ultrafiltration, combined with fluorescence spectroscopy of the upper phase (supernatant) of the filter unit. Passive intracellular delivery of the nanoparticles to HeLa cells was detected by fluorescence confocal microscopy. RESULTS: The QDs were retained tightly and continuously in the polymer matrix, while the organic fluorophores [fluorescein isothiocyanate (FITC), FITC-dextran10,000 and FITC-dextran70,000] were released rapidly from the polymersomes. The detergent Brij significantly increased the retention of FITC-dextran10,000 in the polymer globule. Electroporation up to 1000 V/cm did not induce release of QDs from the polymersomes, but accelerated the release of Brij-treated FITC-dextran10,000 B from the polymer matrix. High-voltage pulses (over 750 V/cm) induced also fragmentation or aggregation of the nanoparticles. QD_labeled polymersomes penetrated passively in cancer cells after 24-hour incubation. CONCLUSION: The results suggest that QD-labeled polymersomes are appropriate fluorescent probes and a nano-drug delivery system with high tracing opportunities for in vitro and in vivo applications. Furthermore, loading polymersomes with organic dyes with different molecular weights (such as FITC-dextrans) is a simple model for visualizing and predicting the rate of release of small organic molecules (e.g. conventional drugs, other contrasts, stabilizers, and supplements) from the polymer matrix.

Delivery of size-controlled long-circulating polymersomes in solid tumours, visualized by quantum dots and optical imaging in vivo.

The present study was designed to investigate whether poly-ion complex hollow vesicles (polymersomes), based on chemically modified chitosan, are appropriate for passive tumour targeting in the context of their application as drug carriers. The experiments were performed on colon cancer-grafted mice. The mice were subjected to anaesthesia and injected intravenously with water-soluble nanoparticles: (1) QD705-labelled polymersomes (average size ∼120 nm; size distribution ∼10%) or (2) native QD705. The optical imaging was carried out on Maestro EX 2.10 In Vivo Imaging System (excitation filter 435-480 nm; emission filter 700 nm, longpass). In the case of QD705, the fluorescence appeared in the tumour area within 1 min after injection and disappeared completely within 60 min. A strong fluorescent signal was detected in the liver on the 30th minute. The visualization of tumour using QD705 was based only on angiogenesis. In the case of QD705-labelled polymersomes, the fluorescence appeared in the tumour area immediately after injection with excellent visualization of blood vessels in the whole body. A strong fluorescent signal was detected in the tumour area within 16 hours. This indicated that QD705-labelled polymersomes were delivered predominantly into the tumour due to their long circulation in the bloodstream and enhanced permeability and retention effect. A very weak fluorescent signal was found in the liver area. The data suggest that size-controlled long-circulating polymersomes are very promising carriers for drug delivery in solid tumours, including delivery of small nanoparticles and contrast substances.