Photochemical disruption of endocytic vesicles before delivery of drugs: a new strategy for cancer therapy

The development of methods for specific delivery of drugs is an important issue for many cancer therapy approaches. Most of macromolecular drugs are taken into the cell through endocytosis and, being unable to escape from endocytic vesicles, eventually are degraded there, which hinders their therapeutic usefulness. We have developed a method, called photochemical internalization, based on light-induced photochemical reactions, disrupting endocytic vesicles specifically within illuminated sites e.g. tumours. Here we present a new drug delivery concept based on photochemical internalization-principle – photochemical disruption of endocytic vesicles before delivery of macromolecules, leading to an instant endosomal release instead of detrimental stay of the molecules in endocytic vesicles. Previously we have shown that illumination applied after the treatment with macromolecules substantially improved their biological effect both in vitro and in vivo. Here we demonstrate that exposure to light before delivery of protein toxin gelonin improves gelonin effect in vitro much more than light after. However, in vitro transfection with reporter genes delivered by non-viral and adenoviral vectors is increased more than 10- and six-fold, respectively, by both photochemical internalization strategies. The possible cellular mechanisms involved, and the potential of this new method for practical application of photochemical internalization concept in cancer therapy are discussed

Makromolekulski prolijekovi. XIII. Vodotopljivi konjugati 17β-estradiola i estradiol-17β-valerata s poliaspartamidnim polimerom

Two hydrosoluble conjugates of 17β-estradiol (ED) and estradiol-17β-valerate (EV) with polyaspartamide polymer were prepared and characterized. ED and EV were first chemically modified and bound to poly,-(N-2-hydroxyethyl-DL-aspartamide)-poly,-(N-2-aminoethyl-DL-aspartamide) (PAHA), a hydrosoluble polyaspartamide-type copolymer bearing both hydroxyl and amino groups. ED was first converted to 17-hemisuccinate (EDS) and then bound to PAHA. In the resulting conjugate PAHA-EDS, the estradiol moiety was linked to the polymer through a 2-aminoethylhemisuccinamide spacer. On the other hand, EV was first converted to estradiol-17-valerate-3-(benzotriazole-1-carboxylate), which readily reacted with amino groups in PAHA affording the polymer-drug conjugate PAHA-EV. In the prepared conjugate PAHA-EV, the estradiol moiety was covalently bound to the polyaspartamide backbone by carbamate linkage, through an ethylenediamine spacer. The polymer-drug conjugates were designed and prepared with the aim to increase water-solubility, bioavailability and to improve drug delivery of the lipophilic estrogen hormone.U radu je opisana priprava i karakterizacija dvaju vodotopljivih polimer-lijek konjugata 17β-estradiola (ED) i estradiol-17β-valerata (EV) s poliaspartamidnim polimerom. ED i EV su prvo kemijski modificirani i vezani na poli,-(N-2-hidroksietil-DL-aspartamid)-poli,-(N-2-aminoetil-DL-aspartamid) (PAHA), vodotopljivi poliaspartamidni kopolimer s hidroksi i amino skupinama. ED je prvo preveden u 17-hemisukcinat (EDS), a zatim vezan na PAHA. U nastalom konjugatu PAHA-EDS estradiolska komponenta vezana je na polimer preko 2-aminoetilhemisukcinatne razmaknice. S druge strane, EV je prvo preveden u estradiol-17-valerat-3-(benzotriazol-1-karboksilat), koji reagira s amino skupinama u PAHA dajući polimer-lijek konjugat PAHA-EV. U tom je konjugatu estradiolska komponenta kovalentno vezana na poliaspartamidnu okosnicu karbamatnom vezom, preko etilenediaminske razmaknice. Polimer-lijek konjugati estradiola dizajnirani su i pripravljeni sa ciljem da se poveća topljivost i bioraspoloživost te isporuka tog lipofilnog estrogenog hormona