Curcumin polymers as anticancer conjugates

Abstract

Curcumin has been shown highly cytotoxic towards various cancer cell lines, but its water-insolubility and instability make its bioavailability exceedingly low and thus it generally demonstrates low anticancer activity in in vivo tests. Herein, we report a novel type of polymer-drug conjugates--the high molecular weight curcumin polymers (polycurcumins) made by condensation polymerization of curcumin. The polycurcumins as backbone-type conjugates have advantages of high drug loading efficiency, fixed drug loading contents, stabilized curcumin in their backbones, and tailored water-solubility. The polycurcumins may have many potential applications and their antitumor activities are investigated in this work. The polycurcumins are cytotoxic to cancer cells, but a polyacetal-based polycurcumin (PCurc 8) is highly cytotoxic to SKOV-3, OVCAR-3 ovarian cancers, and MCF-7 breast cancer cell lines. It can be quickly taken up by cancer cells into their lysosomes, where PCurc 8 hydrolyzes and releases active curcumin. It arrests SKOV-3 cell cycle at G(0)/G(1) phase in vitro and induces cell apoptosis partially through the caspase-3 dependent pathway. In vivo, intravenously (i.v.) injected PCurc 8 shows remarkable antitumor activity in SKOV-3 intraperitoneal (i.p.) xenograft tumor model.