Photochemical Internalization of Tamoxifens Transported by a “Trojan‐Horse” Nanoconjugate into Breast‐Cancer Cell Lines

Abstract

Photochemical internalization (PCI) has shown great promise as at herapeutic alternative for targeted drug delivery by light-harnessed activation. However,i th as only been applicable to therapeutic macromolecules or mediumsized molecules.Herein we describe the use of an amphiphilic, water-soluble porphyrin-b-cyclodextrin conjugate (mTHPPbCD) as a"Trojan horse" to facilitate the endocytosis of CDguest tamoxifens into breast-cancer cells.Upon irradiation, the porphyrin core of mTHPP-bCD expedited endosomal membrane rupture and tamoxifen release into the cytosol, as documented by confocal microscopy. The sustained complexation of mTHPP-bCD with tamoxifen was corroborated by 2D NMR spectroscopya nd FRET studies.F ollowing the application of PCI protocols with 4-hydroxytamoxifen (4-OHT), estrogen-receptor b-positive (Erb+ +,but not ERbÀ)cell groups exhibited extensive cytotoxicity and/or growth suspension even at 72 hafter irradiation.Photodynamic therapy of cancer (PDT) [1] is at reatment modality which utilizes ap hotosensitive drug (photosensitizer,PS), light of the appropriate wavelength, and molecular oxygen as the terminal acceptor of energy or electrons to form singlet oxygen or other deleterious reactive oxygen species (ROS). These species cause local irreversible photodamage to biological substrates within the region of irradiation. A promising evolution of PDT came through the concept of photochemical internalization (PCI).[2] PCI is actually alightcontrolled drug-and gene-delivery modality [3] in which light activation enables spatiotemporal specificity and control over the intracellular drug release.The principle of PCI lies in drug endocytosis.C ells are treated with an amphiphilic PS with high affinity for the plasma membrane (e.g.A mphinex), so that the PS subsequently remains in the membranes of the endosomal vesicles following endocytosis.T he cells are simultaneously treated with drugs or molecules that cannot passively enter cells owing to their unfavorable properties (e.g. hydrophilicity,large size,ornegative charge). Thedrugs are endocytosed and thus confined in endosomes and lysosomes with photosensitizers anchored on their membranes.U pon selective irradiation with light of the appropriate wavelength, the formed ROS,a nd especially 1 O 2 ,m ay cause lipid peroxidation [4] to the endosomal membranes.This transformation potentiates membrane rupture with concomitant release of the endosomal load, thus leading to the cytoplasmic release of ad rug at high concentrations specifically in irradiated tissues.Until now,P CI has been developed and documented for the delivery of therapeutic biomacromolecules and mediumsized molecules,w hich are unable to enter cells in any other manner than endocytosis.However,the majority of the most efficient, widely used, and approved cancer therapeutics are small molecules,w hich can freely enter both target and nontarget cells by passive diffusion. Theu se of PCI technology for the specific delivery of such molecules to cancer lesions in doses much higher t...

The diverse roles of glutathione-associated cell resistance against hypericin photodynamic therapy

“…MCF7 cells perform respiratory ATP production at normoxic conditions and also switch to glycolysis under hypoxia, whilst MDA-MB-231 cells rely on glycolysis for ATP production in both normoxic and hypoxic circumstances [7a,b] . Indeed, as verified by our metabolic studies [7] , [13] , in normal conditions the oxygen consumption rate of MCF7 cells is many fold higher than that of MDA-MB-231 cells. In this context, Pasteur type MCF7 cells, due to their respiratory nature, require more antioxidant protection from electron transport chain leakages and the inevitable creation of free radicals and reactive oxygen species (ROS) such as O 2 -• , H 2 O 2 and deleterious hydroxyl radicals, forming from Fenton reactions catalyzed by transition metals and causing lipid peroxidation [27] .…”

“…In the present project, we endeavoured to mechanistically elucidate the different responses to hypericin (HYP)-PDT between MCF7 and MDA-MB-231 cells, which we observed in the course of experiments, based on their relevant differences. It has to be noted that the recorded difference in photocytotoxicity between the two cell lines was also detected previously, in our recent work on bimodal porphyrin-cyclodextrin system [13] . In that work the phototoxicity was conferred by 5,10,15,20-Tetrakis( m -hydroxyphenyl)-21,23 H -porphyrin.…”

Supramolecular Guest–Host Interactions for the Preparation of Biomedical Materials

“…Similar non-covalent conjugation strategies have been employed using other guest-host pairs such as CB [6] with polyamines to provide targeted delivery of nanocapsules. [95][96] In addition to strategies for noncovalent surface modification, macrocycles have been incorporated into nanoparticles to act as molecular "docking" sites that can facilitate drug loading ( Figure 4B). This carrier functionality has been exploited using amphiphilic CD nanocapsules to entrap tamoxifen, ionic βCD nanoparticles as doxorubicin carriers, and CB [6] particles to carry paclitaxel.…”

Porphyrin-based cationic amphiphilic photosensitisers as potential anticancer, antimicrobial and immunosuppressive agents

“…Cell death is a result of the presence of these cytotoxic macromolecules within the cell rather than PDT . One of the recent successful examples of this methodology includes a porphyrin-β-cyclodextrin conjugate (mTHPP-βCD) that was used to facilitate the release of the chemotherapeutic drug tamoxifen into the cytosol of breast cancer cells (Theodossiou et al 2015).…”