Aristidis Georgopoulos

Mitochondria-targeted liposomes improve the apoptotic and cytotoxic action of sclareol

Current efforts toward improving the effectiveness of drug therapy are increasingly relying on drug-targeting strategies to effectively deliver bioactive molecules to their molecular targets. Pharmaceutical nanocarriers represent a major tool toward this aim, and our efforts have been directed toward achieving nanocarrier-mediated subcellular delivery of drug molecules with mitochondria as the primary subcellular target. Meeting the need for specific subcellular delivery is essential to realizing the full potential of many poorly soluble anticancer drugs. In this article, we report that mitochondria-targeted liposomes significantly improve the apoptotic and cytotoxic action of sclareol, a poorly soluble potential anticancer drug. The results support the broad applicability of our nanocarrier-mediated subcellular targeting approach as a means to improve the effectiveness of certain anticancer therapeutics.

Sclareol induces apoptosis in human HCT116 colon cancer cells in vitro and suppression of HCT116 tumor growth in immunodeficient mice.

Labd-14-ene-8, 13-diol (sclareol) is a labdane-type diterpene, which has demonstrated significant cytotoxic activity against human leukemic cell lines, but its effect on solid tumor-derived cells is uknown. Here, we demonstrate that addition of sclareol to cultures of human colon cancer HCT116 cells results in inhibition of DNA synthesis, arrest of cells at the G1 phase of the cell cycle, activation of caspases-8, -9, PARP degradation, and DNA fragmentation, events characteristic of induction of apoptosis. Intraperitoneal (ip) administration of sclareol alone, at the maximum tolerated dose, was unable to induce suppression of growth of HCT116 tumors established as xenografts in immunodeficient SCID mice. In contrast, ip administration of liposome-encapsulated sclareol, following a specific schedule, induced suppression of tumor growth by arresting tumor cell proliferation as assessed by detecting the presence of the cell proliferation-associated nuclear protein, Ki67, in thin tumor sections. These findings suggest that sclareol incorporated into liposomes may possess chemotherapeutic potential for the treatment of colorectal and other types of human cancer.

Preparation and Characterization of Lyophilized Liposomes with Incorporated Quercetin

Liposomes composed of egg-phosphatidylcholine (EPC) incorporating quercetin (QR) were prepared by the thin-film hydration method (TFHM) and the monophase solution method (MSM). A rapid and slow freeze-drying process was applied for both laboratory and industrial scales. The purpose of this study was to compare the two methods of liposome preparation, and further determine whether the lyophilization process affects the liposome physicochemical characteristics (size, polydispersity index, and ζ-potential) and incorporation of quercetin.

Uptake Studies of Free and Liposomal Sclareol by Mcf-7 and H-460 Human Cancer Cell Lines

The aim of this study was to investigate the uptake of free and liposomal sclareol and its effect on the growth inhibiting activity against MCF-7 and H-460 human cancer cell lines in vitro. Liposomes composed of EPC/DPPG at molar ratio 9:0.1, used to incorporate sclareol, were prepared by the thin-film hydration method followed by sonication. The final liposomal preparation (EPC/DPPG/Sclareol 9:0.1:5 molar ratio) as well as free sclareol (100μM) were incubated up to 96 hours with both cell lines. Sclareol was extracted from cells using the Bligh-Dyer method and was measured by HPTLC/FID. The results showed that the uptake of free sclareol by both cell lines was faster and higher compared to that of its liposomal form. In both cell lines, free sclareol showed high cytotoxicity, while the liposomal sclareol showed reduced cytotoxicity without affecting its ability to reduce the cell growth rate. These findings suggest that liposomal sclareol may possess chemotherapeutic advantages over its free form and can be used for future in vivo experiments for the treatment of these two types of human cancer