zn(ii)-phthalocyanine and Hypoxia

Hypoxia is one of the prominent features of solid tumors. Hypoxia activated prodrugs (HAPs), selectively killing hypoxic cells, possess the potential to transform hypoxia from a nuisance to an advantage in precision therapy. Exhibiting a more significant hypoxic microenvironment, gliomas, as the most frequent and incurable neurological tumors, provide HAPs a more attractive therapeutic prospect. However, the insufficient hypoxia and the obstruction of the blood-brain barrier (BBB) severely limit the activation and bio-availability of HAPs. Herein, a novel nanoparticle iRGD@ZnPc + TPZ was designed and synthesized to achieve gliomas inhibition by encapsulating tirapazamine (TPZ) as a HAP and zinc phthalocyanine (ZnPc) as a photosensitizer to enhance hypoxia. iRGD@ZnPc + TPZ can realize breakthrough BBB, deep penetration, and significant retention in gliomas, which is attributed to the iRGD-mediated receptor targeting and active transport. After being internalized by tumor cells and radiated, ZnPc efficiently consumes intratumoral O

Topics: Antineoplastic Agents; Cell Line, Tumor; Glioma; Humans; Hypoxia; Indoles; Isoindoles; Neoplasms; Organometallic Compounds; Photosensitizing Agents; Prodrugs; Reactive Oxygen Species; Tirapazamine; Tumor Microenvironment; Zinc Compounds

The current study focuses on any influence that depletion of endogenous glutathione in CHO K1 cells may have on the photodynamic action of zinc phthalocyanine (ZnPc).. Two lasers--a HeNe laser, 632.5 nm, maximum power output 3.5 mW, and a Toshiba semiconducting laser, 670 nm, maximum power of 7 mW--were used. Chinese Hamster Ovary cells (CHO K1) were exposed to light, 2-10 J. Cellular reduced glutathione levels [GSH] were depressed prior to exposure to ZnPc and laser light, using buthionine sulphoximine, a potent inhibitor of gamma-glutamylcysteine synthetase. The influence of hypoxic intracellular conditions was studied by reduction of oxygen content of cells by 80% following purging of cell cultures with nitrogen.. In well-aerated cells, doubling times are reduced by the photodynamic action of ZnPc by 29 +/- 6%, fig 2 (p = 0.01). Cells with lowered [GSH] do not show this effect (p = 0.1). When hypoxic cells are studied at normal [GSH], no photodynamic effect is observed (p = 0.1). When cell viability is studied, using the 670-nm laser, a photodynamic effect is observed, (80% fall from controls, p < 0.001), irrespective of the cellular [GSH] level for a single dose of 6 J. This effect is observed in cells with normal [GSH], for varied doses of 2 J and higher (63% fall at 2 J, p < 0.001).. Lowered [GSH] was observed to depress the photodynamic effect of ZnPc when cell-doubling times were the endpoint. The photostimulating effect of ZnPc was similarly suppressed by hypoxic conditions. When cell viability was the endpoint, then a photodynamic effect of ZnPc was observed irrespective of the endogenous [GSH] values.

Topics: Animals; Cell Survival; CHO Cells; Cricetinae; Glutathione; Hypoxia; Indoles; Isoindoles; Organometallic Compounds; Photochemotherapy; Zinc Compounds