Enigmol: A Novel Sphingolipid Analogue with Anticancer Activity against Cancer Cell Lines and In vivo Models for Intestinal and Prostate Cancer

Abstract

Sphingoid bases are cytotoxic for many cancer cell lines, and are thought to contribute to suppression of intestinal tumorigenesis in vivo by ingested sphingolipids. This study explored the behavior of a sphingoid base analog, (2S,3S,5S)-2-amino-3,5-dihydroxyoctadecane (“Enigmol”), that cannot be phosphorylated by sphingosine kinases and is slowly N-acylated, therefore, is more persistent than natural sphingoid bases. Enigmol had potential anti-cancer activity in a National Cancer Institute (NCI-60) cell line screen, and was confirmed to be more cytotoxic and persistent than naturally occurring sphingoid bases using HT29 cells, a colon cancer cell line. Although the molecular targets of sphingoid bases are not well delineated, Enigmol shared one of the mechanisms that has been found for naturally occurring sphingoid bases: to “normalize” the aberrant accumulation of β-catenin in the nucleus and cytoplasm of colon cancer cells due to defect(s) in the adenomatous polyposis coli (APC)/β-catenin regulatory system. Enigmol also had anti-tumor efficacy when administered orally to Min mice, a mouse model with a truncated APC gene product (C57Bl/6JMin/+ mice), decreasing the number of intestinal tumors by half at 0.025 % of the diet (w/w), with no evidence of host toxicity until higher dosages. Enigmol was also tested against the prostate cancer cell lines DU145 and PC-3 in nude mouse xenografts, and suppressed tumor growth in both. Thus, Enigmol represents a novel category of sphingoid base analog that is orally bioavailable and has the potential to be effective against multiple types of cancer.

Novel Synthesis and Biological Evaluation of Enigmols as Therapeutic Agents for Treating Prostate Cancer

“…Over the duration of treatment, animals receiving 5a, 5b, and 5c experienced significantly slower tumor growth rates than those treated with vehicle (p = 0.02, 0.01, and 0.01, respectively, using the mixed model for repeated measurements). The degree of tumor growth inhibition by enigmol (5a) was similar to that seen in previous PC-3 xenograft studies, 15 as well as in the PC-3 docetaxel study ( Figure 3B), highlighting the reproducibility of in vivo efficacy with enigmol. Differences in tumor growth rates were not statistically significant in N-methylenigmol versus controls.…”

“…In vitro, enigmol inhibits both sphingosine kinase and ceramide synthase, 14,15 and it has demonstrated potent anticancer activity in cells derived from multiple types of cancer, including colon, breast, brain, and prostate. 15 Furthermore, in rodent ACS Medicinal Chemistry Letters LETTER models of colon and prostate cancers, enigmol has shown significant oral efficacy, with no evidence of host toxicity at effective doses. Mass spectrometry of lipids extracted from cancer cells treated with enigmol has shown that enigmol is not phosphorylated and, as predicted by our original rationale, was more cytotoxic and more persistent as a free sphingoid base than as an exogenous sphingosine.…”

“…Mass spectrometry of lipids extracted from cancer cells treated with enigmol has shown that enigmol is not phosphorylated and, as predicted by our original rationale, was more cytotoxic and more persistent as a free sphingoid base than as an exogenous sphingosine. 15,16 Enigmol has stereocenters at C-2, C-3, and C-5, and the effect of stereochemistry on its bioactivity is unknown. Therefore, one objective of these studies was to investigate the impact of manipulation of the stereochemistry at C-3 and C-5 on activity.…”

Potential health benefits of sphingolipids in milk and dairy products

“…Evidence of the importance of dietary sphingolipids in fighting colorectal cancer was first described by Dudeja et al (1986), who found differences in both sphingolipid composition and sphingolipid enzyme activities between tumor and normal tissue. Certain sphingolipids are also active against other cancer types, such as enigmol, a sphingoid base analog (Symolon et al, 2011). Sphingoid bases are cytotoxic for many cancer cell lines and are thought to contribute to suppression of intestinal tumorigenesis in vivo by ingested sphingolipids.…”

Potential Targets for Prevention of Colorectal Cancer: a Focus on PI3K/Akt/mTOR and Wnt Pathways

“…Sphingadiene (Kumar et al, 2012) and Enigmal (Symolon et al, 2011) a derivative of sphingolipid potentially reduces the expression as well as, controls the translocation of non-p-β-catenin in APC min mice and colon cancer cells through inhibiting pGSK3β. Similarly Luteolin, a flavone present in green pepper, perilla leaves and peanut inhibits the expression of non-p-β-catenin mediated by the inhibition pGSK3β in AOM-induced colon carcinogenesis.…”