Prior studies reported significant anticancer activities of ceramides. However, anticancer activities of homoserine based ceramides have not been tested. With a view to compare the anticancer activity of ceramides and homoceramides, in the present study, we have synthesized four serine based and four homoserine based C8-ceramide analogues. Since many cancer cells have shown resistance to ceramides, curcumin is now being used in combination with ceramides because of its ability to reverse multidrug resistance. Aimed at targeting curcumin-ceramide combination to tumor endothelial cells, herein we have used a tumor vasculature targeting liposomes of a newly synthesized pegylated RGDGWK-lipopeptide. Importantly, the liposomal formulations of the homoserine based C8-ceramide analogue containing oleyl chain showed more promising antineoplastic activities under both in vitro and systemic settings than the liposomal formulations of commercially available C8-ceramide. Findings in the mouse tumor growth inhibition study revealed synergistic therapeutic benefit from simultaneous delivery of curcumin and a homoserine based ceramide containing oleyl chain to tumor vasculature. Results in RT-PCR and Western blot experiments suggest that inhibition of solid tumor growth is mediated via inhibition of PI3K-Akt signaling pathway. The present structure-activity study is the first report to demonstrate therapeutic promise of curcumin-homoserine based ceramide combination in antiangiogenic cancer therapy.
Keywords: antiangiogenic cancer therapy; ceramide analogues; curcumin−ceramide drug combinations; integrin receptors; pegylated RGDGWK-lipopeptide; tumor vasculature targeting.