Ceramide–Rubusoside Nanomicelles, a Potential Therapeutic Approach to Target Cancers Carrying p53 Missense Mutations

Abstract

◥Ceramide (Cer) is an active cellular sphingolipid that can induce apoptosis or proliferation-arrest of cancer cells. Nanoparticle-based delivery offers an effective approach for overcoming bioavailability and biopharmaceutics issues attributable to the pronounced hydrophobicity of Cer. Missense mutations of the protein p53, which have been detected in approximately 42% of cancer cases, not only lose the tumor suppression activity of wild-type p53, but also gain oncogenic functions promoting tumor progression and drug resistance. Our previous works showed that cellular Cer can eradicate cancer cells that carry a p53 deletion-mutation by modulating alternative pre-mRNA splicing, restoring wild-type p53 protein expression. Here, we report that new ceramiderubusoside (Cer-RUB) nanomicelles considerably enhance Cer in vivo bioavailability and restore p53-dependent tumor suppression in cancer cells carrying a p53 missense mutation.Natural RUB encapsulated short-chain C 6 -Cer so as to form Cer-RUB nanomicelles ($32 nm in diameter) that substantially enhanced Cer solubility and its levels in tissues and tumors of mice dosed intraperitoneally. Intriguingly, Cer-RUB nanomicelle treatments restored p53-dependent tumor suppression and sensitivity to cisplatin in OVCAR-3 ovarian cancer cells and xenograft tumors carrying p53 R248Q mutation. Moreover, Cer-RUB nanomicelles showed no signs of significant nonspecific toxicity to noncancerous cells or normal tissues, including bone marrow. Furthermore, Cer-RUB nanomicelles restored p53 phosphorylated protein and downstream function to wild-type levels in p53 R172H /þ transgenic mice. Altogether, this study, for the first time, indicates that natural Cer-RUB nanomicelles offer a feasible approach for efficaciously and safely targeting cancers carrying p53 missense mutations.

Gb3‐cSrc complex in glycosphingolipid‐enriched microdomains contributes to the expression of p53 mutant protein and cancer drug resistance via β‐catenin–activated RNA methylation

“…Furthermore, homozygous TP53 mutation‐carrying cancer cells, either WiDr ( TP53 R273H +/+ ) or OVCAR3 ( TP53 R248Q +/+ ), exhibited greater resistance (Figure 1B). 31 When comparing GCS activities among cell lines under doxorubicin treatments, we found substantially higher GCS activities in p53 mutant‐carrying cancer cells, particularly in homozygous WiDr cells (Figure 2B). Interestingly, WiDr cells were found to be more sensitive to inhibition of GCS by Genz‐161 than were cells of the TP53‐Dox or SW48‐Dox lines (Figure 2B).…”

“…In addition to other oncogenic effects on tumor progression, p53 missense mutants are causative of cancer drug resistance 20,27,28 . Restoring the expression of wild‐type p53 or reactivating p53 function resensitizes cancer cells carrying TP53 mutations to anticancer treatments 22,29–31 …”

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“…Ceramides (Cer), which are sphingolipids, can act as cellular signals to induce cancer cells to apoptosis, proliferation-arrest or autophagy [4]. Recently, small Cer-RUB nanomicelles were identified as an agent for restoring p53 tumor suppression and overcoming drug resistance as well as cancer progression in ovarian cancer cells and tumors that carry p53 missense G248Q mutation [5].…”

“…Exogenously delivered C 6 -Cer not only increases levels of endogenous Cers, but also displays greater potency in inducing cell death. C 6 -Cer is more slowly glucosylated (by glucosylceramide synthase, GCS), and may be converted more slowly to the corresponding sphingosine-1-phosphate (S1P) by deacylation (ceramidases) followed by phosphorylation (sphingosine kinases) [5][6][7]. By exploiting these two prominent diversion pathways, metastatic cancers can suppress free Cer levels, and furthermore, mount resistance to anticancer drugs via elevated glucosylceramide and S1P [4,7].…”

“…We did not detect any significant nonspecific toxicity of RUB in cell culture or animal studies, even at significantly higher concentrations or amounts than with the RUB-encapsulated Cer at the highest doses used. Pharmacokinetic studies further indicate Cer-RUB nanomicelles can effectively deliver C 6 -Cer into tumors and other tissues for various prospective therapeutic purposes, when administered intraperitoneally or orally [5,8].…”