Interactive Transport, Subcellular Relocation and Enhanced Phototoxicity of Hypericin Encapsulated in Guanidinylated Liposomes via Molecular Recognition^†

Abstract

Hypericin (HYP), a photocytotoxic phenanthroperylenquinone was encapsulated in liposomes outfitted with guanidinium-bearing lipids to ensure efficient cell binding through molecular recognition with anionic groups resident on the plasma membrane. The uptake of HYP encapsulated in these liposomes by DU145 human prostate cancer cells, was studied employing fluorescence, versus nonguadinylated liposomes and free HYP. The subcellular localization was in all cases studied by confocal microscopy employing specific subcellular organelle probes. The photocytotoxicity of HYP was assessed, 24 h following irradiation with 15 mWcm(-2) light through a GG 495 Schott filter, by a standard tetrazolium to formazan assay (XTT). HYP uptake by DU145 cells was found to be profoundly enhanced by using guanidinylated liposomes. Also the distance of the guanidinium group from the liposomal surface was found to significantly affect HYP loading, subcellular localization and phototoxicity. The two different modes of liposome cell internalization observed, i.e. plasma membrane fusion and endocytosis, were found to greatly affect the phototoxicity of HYP. Molecular recognition was overall appraised as a promising, novel route for photodynamic therapy, profoundly enhancing its efficacy. HYP encapsulated in liposomes-bearing guanidinium groups was more efficiently taken up by cells, leading to enhanced phototoxicity, in contrast to HYP encapsulated in their nonguanidinylated counterparts.

Alterations in dysadherin expression and F-actin reorganization: a possible mechanism of hypericin-mediated photodynamic therapy in colon adenocarcinoma cells

“…In various cancer cells after HYP-mediated PDT, cell death induction was related with mitochondrial membrane potential and mitochondrial enzyme alterations, resulted in hydroxyl radical formation and lipid peroxidation (Theodossiou et al 2009). It was reported that HYP is accumulated mostly in mitochondria, endoplasmic reticulum, Golgi appartus and slightly in lysosomal membrane (Galanou et al 2008). MTT assay (based on mitochondrial activity) and neutral red assay (based on lysosomal activity, data not shown) were performed in order to determine cytotoxicity.…”

Anti- and Pro-apoptotic Bcl2 Proteins Distribution and Metabolic Profile in Human Coronary Aorta Endothelial Cells Before and After HypPDT

“…PDT including HypPDT often induces damage to the endothelium and can result in angiogenesis, which is the major reason for the PDT treatment failure [9,[13][14][15][16][17][18]. In addition, in most PDT treatments, PS is administered systemically and can result in high light independent exposure of endothelial cells to PS [5].…”

“…The molecular mechanisms underlying PDT, and specifically HypPDT, are not completely understood, although it has been shown that the sub-cellular Hyp localization and distribution determine which signaling pathway will lead to cell death [6,[8][9][10][11][12]. Although HypPDT has been found to be an efficient inducer of cell death, some in vivo studies indicate that PDT also activates survival pathways, which ultimately can lead to tumor survival and recurrence [13][14][15][16][17][18]. Cell responses to HypPDT are highly dependent on the Hyp intracellular localization and accumulation [11,13,14,19].…”

“…Although HypPDT has been found to be an efficient inducer of cell death, some in vivo studies indicate that PDT also activates survival pathways, which ultimately can lead to tumor survival and recurrence [13][14][15][16][17][18]. Cell responses to HypPDT are highly dependent on the Hyp intracellular localization and accumulation [11,13,14,19]. The Hyp displays a selective affinity to lipid membranes in general [20], and more specifically, it has been found to accumulate in the endoplasmic reticulum (ER) and Golgi [11,21], lysosomes [22,23] and mitochondria [24].…”

Solubilization of poorly soluble photosensitizer hypericin by polymeric micelles and polyethylene glycol

“…Up to now, several delivery systems have been utilized for Hyp transport: Hyploaded polymeric nanoparticles of polylactic acid (ZeisserLabouebe et al 2006;Zeisser-Labouebe et al 2009), Hyp bound to polyvinyl-pyrrolidone (Kubin et al 2008) and N-methyl-pyrrolidone (Saw et al 2005(Saw et al , 2006, Hyp embedded in liposomes (Angelini et al 1997;Roslaniec et al 2000;Galanou et al 2008), Hyp in transferin conjugated polyethylen glycol (PEG)-liposomes (Derycke and de Witte 2002) and DMSO-PEG solutions (Huygens et al 2005). The transport of Hyp in a complex with delivery system usually results in improved tumor to normal tissues ratio and a relatively fast elimination of Hyp from a biological organism (van de Putte et al 2006).…”