68 Ga-labeled, imatinib encapsulated, theranostic liposomes: Formulation, characterization, and in vitro evaluation of anticancer activity.

Cancer is still a global health problem. Among cancer types, breast cancer is the most frequently diagnosed one, and it causes a high mortality rate if not diagnosed in the early stages. In our study, imatinib encapsulated, nanosized, neutral/cationic liposome formulations were prepared as theranostic agents for breast cancer. After the characterization studies in which all liposomes exhibited proper profile owing to their particle size between 133 and 250 nm, polydispersity index values lower than 0.4, neutral and cationic zeta potential values, and high drug encapsulation efficiency, controlled drug release behaviors with zero-order kinetic were obtained. The higher than 90% radiolabeling efficiency values were obtained thanks to the determination of optimum radiolabeling condition (80°C temperature, 5 mCi radioactivity, and 10 min incubation period). According to the resazurin assay evaluating the cytotoxic profile of liposomes on MCF7 cells, neutral empty liposome was found as biocompatible, while both cationic liposomes (empty and drug-loaded ones) exhibited high nonspecific cytotoxicity at even low drug concentration due to the existence of stearyl amine in the formulations. However, dose-dependent cytotoxic effect and the highest cellular binding capacity were obtained by imatinib loaded neutral liposomes. In conclusion, 68 Ga-radiolabeled, imatinib-loaded, neutral, nanosized liposome formulation is the most promising one as a theranostic agent among all formulations.

Cell Viability Assay with 3D Prostate Tumor Spheroids.

WST-8 (Cell Counting Kit 8; CCK-8) is the last generation tetrazolium-based cell viability assay and has recently been accepted as a validated method for measuring the cell viability of 3D in vitro models. Here, we describe how to form 3D prostate tumor spheroids using the polyHEMA technique, apply drug treatments and WST-8 assay to these spheroids, and calculate their cell viability. The advantages of our protocol are the formation of spheroids without adding extracellular matrix components, and the elimination of the critique handling process needed for transferring spheroids. Although this protocol exemplifies the determination of percentage cell viability in PC-3 prostate tumor spheroids, it can be adapted and optimized for other prostate cell lines and other types of cancers.

Development of EphA2 siRNA-loaded lipid nanoparticles and combination with a small-molecule histone demethylase inhibitor in prostate cancer cells and tumor spheroids.

BACKGROUND: siRNAs hold a great potential for cancer therapy, however, poor stability in body fluids and low cellular uptake limit their use in the clinic. To enhance the bioavailability of siRNAs in tumors, novel, safe, and effective carriers are needed. RESULTS: Here, we developed cationic solid lipid nanoparticles (cSLNs) to carry siRNAs targeting EphA2 receptor tyrosine kinase (siEphA2), which is overexpressed in many solid tumors including prostate cancer. Using DDAB cationic lipid instead of DOTMA reduced nanoparticle size and enhanced both cellular uptake and gene silencing in prostate cancer cells. DDAB-cSLN showed better cellular uptake efficiency with similar silencing compared to commercial transfection reagent (Dharmafect 2). After verifying the efficacy of siEphA2-loaded nanoparticles, we further evaluated a potential combination with a histone lysine demethylase inhibitor, JIB-04. Silencing EphA2 by siEphA2-loaded DDAB-cSLN did not affect the viability (2D or 3D culture), migration, nor clonogenicity of PC-3 cells alone. However, upon co-administration with JIB-04, there was a decrease in cellular responses. Furthermore, JIB-04 decreased EphA2 expression, and thus, silencing by siEphA2-loaded nanoparticles was further increased with co-treatment. CONCLUSIONS: We have successfully developed a novel siRNA-loaded lipid nanoparticle for targeting EphA2. Moreover, preliminary results of the effects of JIB-04, alone and in combination with siEphA2, on prostate cancer cells and prostate cancer tumor spheroids were presented for the first time. Our delivery system provides high transfection efficiency and shows great promise for targeting other genes and cancer types in further in vitro and in vivo studies.

A promising approach to develop nanostructured lipid carriers from solid lipid nanoparticles: preparation, characterization, cytotoxicity and nucleic acid binding ability.

We aimed to develop nanostructured lipid carriers (NLCs) displaying similar characteristics - particle size, polydispersity index, and zeta potential - with the model solid lipid nanoparticles (SLNs) for better comparability. By considering the hydrophilic-lipophilic balance values of solid and liquid lipids, five out of six NLCs and eight out of eight cationic NLCs (cNLCs) were successfully prepared with similar characteristics to their precursor SLN and cationic SLNs (cSLNs), respectively. Among cationic formulations, two cSLNs containing different surfactant/co-surfactant concentrations (4% and 8% S/CoS; w/w) and their cNLC versions prepared with Labrafac lipophile WL 1349 (LWL) or Labrafac PG were selected to compare cytotoxicity, stability, and nucleic acid binding ability. All formulations are well-tolerated by L-929 cells, cSLNs being least toxic. The formulations containing 4% S/CoS had higher stability after 24-months. All nanoparticles formed complexes with pDNA (Binding ability: cNLCs > cSLNs). cSLN and LWL-cNLC containing 4% S/CoS showed the highest pDNA binding capacity in each group, and their spherical/oval shape was revealed by electron microscopy. However, they did not form complexes with siRNA. The developed approach has the potential to simplify the production of (c)NLCs having similar physicochemical properties with the optimum (c)SLN and may provide better insight for (c)SLN vs.

Nutlin3a-Loaded Nanoparticles Show Enhanced Apoptotic Activity on Prostate Cancer Cells.

Escape from apoptosis, one of the characteristic features of cancer cells, is a case that reduces the therapeutic efficacy of apoptosis-inducing molecules used in the cancer treatment. Stabilization of the P53 protein, which is responsible for the regulation of apoptosis mechanism in the cell, is therefore an important therapeutic goal. Nutlin3a inhibits the degradation of the P53 protein, triggers P53-mediated apoptosis in cancer cells and enhances the effectiveness of chemotherapeutics. However, its low aqueous solubility is the major disadvantage when it comes to in vivo administration. In order to facilitate an aqueous formulation of Nutlin3a and to enhance its apoptotic activity on cancer cells, Nutlin3a was encapsulated in solid lipid nanoparticles (SLNs) prepared by Ouzo method. Physicochemical characterization was performed and activity of apoptosis induction on wild-type P53 expressing LNCaP prostate cancer cell line was evaluated. Nutlin3a-loaded cationic solid lipid nanoparticles were found to stabilize functional P53 at protein level. In addition, induction rate of apoptosis by nanoparticles was higher than Nutlin3a solution in DMSO, proving this nanoparticle formulation is a promising candidate for increasing the efficiency of Nutlin3a for P53(+) cancer cases. Thus, it is anticipated that the results will contribute to evaluate the use of lipid-based nanocarriers to enhance the therapeutic potential of small molecules that are important in cancer cure.