Short-chain C6 ceramide sensitizes AT406-induced anti-pancreatic cancer cell activity

C6 Ceramide Inhibits Canine Mammary Cancer Growth and Metastasis by Targeting EGR3 through JAK1/STAT3 Signaling

Cancer is the leading cause of death in both humans and companion animals. Canine mammary tumor is an important disease with a high incidence and metastasis rate, and its poor prognosis remains a serious clinical challenge. C6 ceramide is a short-chain sphingolipid metabolite with powerful potential as a tumor suppressor. However, the specific impact of C6 ceramide on canine mammary cancer remains unclear. However, the effects of C6 ceramide in canine mammary cancer are still unclear. Therefore, we investigated the role of C6 ceramide in the progress of canine mammary cancer and explored its potential mechanism. C6 ceramide inhibited cell growth by regulating the cell cycle without involving apoptosis. Additionally, C6 ceramide inhibited the migration and invasion of CHMp cells. In vivo, C6 ceramide decreased tumor growth and metastasis in the lungs without side effects. Further investigation found that the knockdown of EGR3 expression led to a noticeable increase in proliferation and migration by upregulating the expressions of pJAK1 and pSTAT3, thus activating the JAK1/STAT3 signaling pathway. In conclusion, C6 ceramide inhibits canine mammary cancer growth and metastasis by targeting EGR3 through the regulation of the JAK1/STAT3 signaling pathway. This study implicates the mechanisms underlying the anti-tumor activity of C6 ceramide and demonstrates the potential of EGR3 as a novel target for treating canine mammary cancer.

Natural Products and Small Molecules Targeting Cellular Ceramide Metabolism to Enhance Apoptosis in Cancer Cells

Molecular targeting strategies have been used for years in order to control cancer progression and are often based on targeting various enzymes involved in metabolic pathways. Keeping this in mind, it is essential to determine the role of each enzyme in a particular metabolic pathway. In this review, we provide in-depth information on various enzymes such as ceramidase, sphingosine kinase, sphingomyelin synthase, dihydroceramide desaturase, and ceramide synthase which are associated with various types of cancers. We also discuss the physicochemical properties of well-studied inhibitors with natural product origins and their related structures in terms of these enzymes. Targeting ceramide metabolism exhibited promising mono- and combination therapies at preclinical stages in preventing cancer progression and cemented the significance of sphingolipid metabolism in cancer treatments. Targeting ceramide-metabolizing enzymes will help medicinal chemists design potent and selective small molecules for treating cancer progression at various levels.

Review of available "extraction + purification" methods of natural ceramides and their feasibility for sewage sludge analysis

Natural ceramide, a biologically active compound present in plants, has been used widely in food, cosmetics, and pharmaceutical industries. Abundant ceramide has been detected in sewage sludge, which has inspired the idea to recycle ceramide from it. Therefore, the methods of extracting, purifying, and detecting ceramides from plants were reviewed, with the aim to establish methods to get condensed ceramide from sludge. Ceramide extraction methods include traditional methods (maceration, reflux, and Soxhlet extraction) and green technologies (ultrasound-assisted, microwave-assisted, and supercritical fluid extraction). In the past two decades, more than 70% of the articles have used traditional methods. However, green extraction methods are gradually improved and showed high extraction efficiency with lower solvent consumed. The preferred technique for ceramide purification is chromatography. Common solvent systems include chloroform-methanol, n-hexane-ethyl acetate, petroleum ether-ethyl acetate, and petroleum ether-acetone. For structural determination of ceramide, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectrometry are used in combination. Among quantitative analysis methods for ceramide, liquid chromatography-mass spectrometry was the most accurate. This review concludes that with our prilemenary experiment results it is feasible to apply the plant "extraction + purification" process of ceramide to sludge, but more optimization need to be performed to get better results.

C6 Ceramide (d18:1/6:0) as a Novel Treatment of Cutaneous T Cell Lymphoma

Cutaneous T cell lymphomas (CTCLs) represent a heterogeneous group of T cell lymphomas that primarily affect the skin. The most frequent forms of CTCL are mycosis fungoides and Sézary syndrome. Both are characterized by frequent recurrence, developing chronic conditions and high mortality with a lack of a curative treatment. In this study, we evaluated the effect of short-chain, cell-permeable C6 Ceramide (C6Cer) on CTCL cell lines and keratinocytes. C6Cer significantly reduced cell viability of CTCL cell lines and induced cell death via apoptosis and necrosis. In contrast, primary human keratinocytes and HaCaT keratinocytes were less affected by C6Cer. Both keratinocyte cell lines showed higher expressions of ceramide catabolizing enzymes and HaCaT keratinocytes were able to metabolize C6Cer faster and more efficiently than CTCL cell lines, which might explain the observed protective effects. Along with other existing skin-directed therapies, C6Cer could be a novel well-tolerated drug for the topical treatment of CTCL.

The strong inhibitory effect of combining anti-cancer drugs AT406 and rocaglamide with blue LED irradiation on colorectal cancer cells

There is still no satisfying method to treat colorectal cancer (CRC) currently. Inspired by cocktail therapy, the combination of 465 nm blue LED irradiation and two multi-target anticancer agents AT406 and Rocaglamide has been investigated as an innovative way to treat colorectal cancer cells in vitro. It showed a strong inhibitory effect on colorectal cancer cells, and its side effects on human normal cells are negligible. When applied to HCT116 cells, it can achieve an apoptotic rate up to 95%. It is also seen to significantly inhibit proliferation of HT29 cells. Furthermore, little to no cell inhibition or damage of normal MRC-5 cells were seen after treatment. The combination of blue LED irradiation and two anti-cancer drugs causes apoptosis of colorectal cancer cells by activating the apoptotic pathway, inhibiting autophagy and proliferation pathways as well as the production of reactive oxygen species (ROS).

Rubusoside-assisted solubilization of poorly soluble C6-Ceramide for a pilot pharmacokinetic study

Although C₆-Ceramide has attracted much attention as a possible tumor suppressor, the delivery of C₆-Ceramide is still challenging due to its inherent hydrophobicity and insolubility. In this study we explored the use of a natural compound rubusoside (RUB) as a solubilizer to enhance the solubility of a fluorescence-labeled C₆-Ceramide (NBD C₆-Ceramide) and to characterize its pharmacokinetics and tissue distribution in an animal model. RUB significantly enhanced the solubility of NBD C₆-Ceramide by forming nanomicelles, and efficiently delivered NBD C₆-Ceramide in rats by oral and intravenous administration. RUB loaded 1.96 % of NBD C₆-Ceramide in the nanomicelles and solubilized it to a concentration of 3.6 mg/mL in water. NBD C₆-Ceramide in nanomicelles remained stable in aqueous solutions, allowing intravenous administration without the use of any organic solvents or surfactants. After oral administration, NBD C₆-Ceramide rapidly rose to peak plasma concentrations within the first 90 min, distributed to tissues, and remained in vivo for more than 24 h. Tissular levels of NBD C₆-Ceramide from high to low were associated with heart, lung, cerebellum, testicle, spleen, liver, kidney, and brain. Altogether, our study demonstrated that RUB-assisted nanomicelles can serve as an efficient and convenient delivery system for short-chain C₆-Ceramide and enable in vivo evaluation of potential new cancer treatments.

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

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 ceramide-rubusoside (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 C₆-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^/+ 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.

Novel Sphingolipid-Based Cancer Therapeutics in the Personalized Medicine Era

Sphingolipids are bioactive lipids that participate in a wide variety of biological mechanisms, including cell death and proliferation. The myriad of pro-death and pro-survival cellular pathways involving sphingolipids provide a plethora of opportunities for dysregulation in cancers. In recent years, modulation of these sphingolipid metabolic pathways has been in the forefront of drug discovery for cancer therapeutics. About two decades ago, researchers first showed that standard of care treatments, e.g., chemotherapeutics and radiation, modulate sphingolipid metabolism to increase endogenous ceramides, which kill cancer cells. Strikingly, resistance to these treatments has also been linked to altered sphingolipid metabolism, favoring lipid species that ultimately lead to cell survival. To this end, many inhibitors of sphingolipid metabolism have been developed to further define not only our understanding of these pathways but also to potentially serve as therapeutic interventions. Therefore, understanding how to better use these new drugs that target sphingolipid metabolism, either alone or in combination with current cancer treatments, holds great potential for cancer control. While sphingolipids in cancer have been reviewed previously (Hannun & Obeid, 2018; Lee & Kolesnick, 2017; Morad & Cabot, 2013; Newton, Lima, Maceyka, & Spiegel, 2015; Ogretmen, 2018; Ryland, Fox, Liu, Loughran, & Kester, 2011) in this chapter, we present a comprehensive review on how standard of care therapeutics affects sphingolipid metabolism, the current landscape of sphingolipid inhibitors, and the clinical utility of sphingolipid-based cancer therapeutics.

Identification of mTOR as a primary resistance factor of the IAP antagonist AT406 in hepatocellular carcinoma cells

Dysregulation of inhibitor of apoptosis (IAP) proteins (IAPs) in hepatocellular carcinoma (HCC) is often associated with poor prognosis. Here we showed that AT406, an IAP antagonist, was cytotoxic and pro-apoptotic to both established (HepG2, SMMC-7721 lines) and primary HCC cells. Activation of mTOR could be a key resistance factor of AT406 in HCC cells. mTOR inhibition (by OSI-027), kinase-dead mutation or knockdown remarkably enhanced AT406-induced lethality in HCC cells. Reversely, forced-activation of mTOR by adding SC79 or exogenous expressing a constitutively active S6K1 (T389E) attenuated AT406-induced cytotoxicity against HCC cells. We showed that AT406 induced degradation of IAPs (cIAP-1 and XIAP), but didn't affect another anti-apoptosis protein Mcl-1. Co-treatment of OSI-027 caused simultaneous Mcl-1 downregulation to overcome AT406's resistance. Significantly, shRNA knockdown of Mcl-1 remarkably facilitated AT406-induced apoptosis in HCC cells. In vivo, AT406 oral administration suppressed HepG2 tumor growth in nude mice. Its activity was potentiated with co-administration of OSI-027. We conclude that mTOR could be a key resistance factor of AT406 in HCC cells.

The sphingosine kinase 2 inhibitor ABC294640 inhibits cervical carcinoma cell growth

ABC294640 is a specific sphingosine kinase 2 (SphK2) inhibitor. The anti-cervical carcinoma activity by ABC294640 was tested in this study. ABC294640 inhibited in vitro growth of the established (C33A and HeLa lines) and primary human cervical carcinoma cells. The SphK2 inhibitor also induced G1-S arrest and apoptosis in cervical carcinoma cells. It was yet non-cytotoxic to SphK2-low human cervical epithelial cells. ABC294640 inhibited SphK activation, causing sphingosine-1-phosphate depletion, signal transducer and activator of transcription 3 in-activation and ceramide production. Bcl-2 is a key resistance factor of ABC294640. Pharmacological Bcl-2 inhibition or Bcl-2 shRNA potentiated ABC294640-induced C33A cell growth inhibition and apoptosis. On the other hand, exogenous over-expression of Bcl-2 attenuated ABC294640's cytotoxicity against C33A cells. In vivo, ABC294640 administration inhibited C33A xenograft tumor growth in mice. Co-administration of the Bcl-2 inhibitor GDC-0199 further potentiated ABC294640's anti-tumor activity. Together, we suggest that ABC294640 might have translational value for the treatment of human cervical carcinoma.