title: Systemic delivery of liposomal short-chain ceramide limits solid tumor growth in murine models of breast adenocarcinoma.
abstract: In vitro tumor cell culture models have illuminated the potential therapeutic utility of elevating the intracellular concentration of the antimitogenic and proapoptotic sphingolipid, ceramide. However, although cell-permeable, short-chain ceramide is an effective apoptotic agent in vitro, its use as an in vivo, systemically delivered therapeutic is limited by its inherent lipid hydrophobicity and physicochemical properties. Here, we report that the systemic i.v. delivery of C6-ceramide (C6) in a pegylated liposomal formulation significantly limited the growth of solid tumors in a syngeneic BALB/c mouse tumor model of breast adenocarcinoma. Over a 3-week treatment period, a well-tolerated dose of 36 mg/kg liposomal-C6 elicited a >6-fold reduction in tumor size compared with empty ghost liposomes. Histologic analyses of solid tumors from liposomal-C6-treated mice showed a marked increase in the presence of apoptotic cells, with a coincident decrease in cellular proliferation and in the development of a microvessel network. Liposomal-C6 accumulated within caveolae and mitochondria, suggesting putative mechanisms by which ceramide induces selective cancer cell cytotoxicity. A pharmacokinetic analysis of systemic liposomal-C6 delivery showed that the pegylated liposomal formulation follows first-order kinetics in the blood and achieves a steady-state concentration in tumor tissue. Confirming the therapeutic utility of i.v. liposomal-C6 administration, we also shown diminution of solid tumor growth in a human xenograft model of breast cancer. Together, these results indicate that bioactive ceramide analogues can be incorporated into pegylated liposomal vehicles for improved solubility, drug delivery, and antineoplastic efficacy.
authors.affiliation: Department of Pharmacology, Pennsylvania State College of Medicine, Hershey, Pennsylvania 17033, USA.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Stover
authors.forename: Arati
authors.initials: A
authors.lastname: Sharma
authors.forename: Gavin P
authors.initials: GP
authors.lastname: Robertson
authors.forename: Mark
authors.initials: M
authors.lastname: Kester
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000517:prevention & control; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D021941:Caveolae / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002518:Ceramides / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008081:Liposomes; D008325:Mammary Neoplasms, Experimental / Q000473:pathology / Q000517:prevention & control*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000473:pathology / Q000517:prevention & control; D023041:Xenograft Model Antitumor Assays
chemical_list: D002518:Ceramides; D008081:Liposomes; C101954:N-caproylsphingosine