Issue 3, 2017

A multi-functional PEGylated gold(iii) compound: potent anti-cancer properties and self-assembly into nanostructures for drug co-delivery

Abstract

Gold(III) porphyrin–PEG conjugates [Au(TPP–COO–PEG5000–OCH3)]Cl (1) and [Au(TPP–CONH–PEG5000–OCH3)]Cl (2) have been synthesized and characterized. Based on the amphiphilic character of the conjugates, they were found to undergo self-assembly into nanostructures with size 120–200 nm and this did not require the presence of other surfactants or components for nano-assembly, unlike most conventional drug nano-formulations. With a readily hydrolyzable ester linkage, chemotherapeutic [Au(TPP–COOH)]+ exhibited triggered release from the conjugate 1 in acidic buffer solution as well as in vitro and in vivo without the formation of toxic side products. The nanostructures of 1 showed higher cellular uptake into cancer cells compared to non-tumorigenic cells, owing to their energy-dependent uptake mechanism. This, together with a generally higher metabolic rate and more acidic nature of cancer cells which can lead to faster hydrolysis of the ester bond, afforded 1 with excellent selectivity in killing cancer cells compared with non-tumorigenic cells in vitro. This was corroborated by fluorescence microscopy imaging and flow cytometric analysis of co-culture model of colon cancer (HCT116) and normal colon (NCM460) cells. In vivo experiments showed that treatment of nude mice bearing HCT116 xenografts with 1 resulted in significant inhibition of tumor growth and, more importantly, minimal systemic toxicity as revealed by histopathological analysis of tissue sections and blood biochemisty. The latter is explained by a lower accumulation of 1 in organs of treated mice at its effective dosage, as compared to that of other gold(III) porphyrin complexes. Co-assembly of 1 and doxorubicin resulted in encapsulation of doxorubicin by the nanostructures of 1. The nanocomposites demonstrated a strong synergism on killing cancer cells and could overcome efflux pump-mediated drug-resistance in a doxorubicin-resistant ovarian cancer cell line (A2780adr) which was found in cells incubated with doxorubicin alone. Also, the nanocomposites accumulated more slowly in non-tumorigenic cells, resulting in a lower toxicity toward non-tumorigenic cells. These results indicate the potential application of 1 not only as an anti-cancer agent but also as a nanoscale drug carrier for chemotherapy.

Graphical abstract: A multi-functional PEGylated gold(iii) compound: potent anti-cancer properties and self-assembly into nanostructures for drug co-delivery

Supplementary files

Article information

Article type
Edge Article
Submitted
20 Jul 2016
Accepted
08 Nov 2016
First published
22 Nov 2016
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2017,8, 1942-1953

A multi-functional PEGylated gold(III) compound: potent anti-cancer properties and self-assembly into nanostructures for drug co-delivery

C. Y. Chung, S. Fung, K. Tong, P. Wan, C. Lok, Y. Huang, T. Chen and C. Che, Chem. Sci., 2017, 8, 1942 DOI: 10.1039/C6SC03210A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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