NOVEL GEMINI SURFACTANT-BASED GENE/DRUG DELIVERY SYSTEMS Potential Applications in Melanoma Therapy

Abstract

Melanoma is the most life-threatening form of skin cancer and world-wide statistics show an alarming increase in melanoma incidence and mortality. The aim of my work was to develop and investigate the potential applications of novel drug/gene delivery systems in melanoma therapy. In the first research theme, I explored the application of targeted-gemini surfactant-based gene delivery system in melanoma therapy. Two cancer targeting-peptides (cyclic-RGD and p18-4]) were used to develop melanoma-targeting lipoplexes. Different formulations and transfection techniques were developed and evaluated. Physicochemical and structural properties of peptide-modified lipoplexes were examined. In vitro transfection efficiency and cellular toxicity of the developed lipoplexes were evaluated in human melanoma cell line. Results showed that peptide-modified gemini surfactant-based lipoplexes significantly enhanced the gene transfection activity in A375 cells compared to the non-targeted formulation. In the second research theme, I investigated the application of a novel β-cyclodextrin (βCD) modified gemini surfactant as a potential drug delivery system in melanoma. βCD was chemically attached to a gemini surfactant, producing a novel βCD-conjugate (18:1βCDg) that can self-assemble and form supramolecular nano-complexes. The 18:1βCDg was designed to combine the solubilizing capacity of the βCD and the cell-penetrating ability of the gemini surfactant. Melphalan (Mel) was selected as a model compound for a poorly soluble drug. To assess the solubilizing efficiency of 18:1βCDg, flow-injection analysis tandem mass spectrometric (FIA-MS/MS) methods were developed. FIA-MS/MS results showed a significant increase (over three-fold) in the aqueous solubility of Mel, at 2:1 host-guest molar ratio. Supporting this finding is the fact that One-/two-dimensional Rotating-frame-Overhauser Spectroscopy-Nuclear Magnetic Resonance (1D/2D ROESY-NMR) results indicated the formation of stable 18:1βCDg/Mel inclusion complex at the same molar ratio. In vitro evaluations showed that the optimized 18:1βCDg/Mel complexes significantly improved the chemotherapeutic efficacy of Mel in monolayer, 3D spheroid and in Mel-resistant melanoma cell lines. Subsequently, in vivo acute toxicity in Sprague-Dawley rats and hemolysis assessment were conducted to determine the carrier’s safety profile. It was shown that 18:1βCDg has low hemolytic effect in comparison to native βCD and basic gemini surfactant molecule. Acute toxicity assessments indicated that 18:1βCDg was well-tolerated without significant toxicity.