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Abstract Background The majority of those diagnosed with aortic aneurysm in the UK are older, multi-morbid patients. Decision-making as to who may benefit from intervention (open or endovascular aneurysm repair) is highly variable across the NHS (as is the mode of intervention), in part because there are no detailed guidelines or consensus on preoperative assessment. Thus, there is likely to be significant variation in the pre-operative assessment and optimisation of these patients. Methods A survey was designed to understand current practice and attitudes of vascular surgeons and vascular anaesthetists in the UK regarding preoperative assessment and optimisation of patients undergoing elective aortic aneurysm repair. The survey was reviewed and validated by an expert panel, then distributed electronically to all vascular surgical and vascular anaesthetic leads in the UK. Results Overall, the response rate was 68%. The responses were varied between surgeons and anaesthetists, with differences reported in the preoperative assessment and optimisation of patients, the approach to shared decision-making, and the perioperative pathway. Conclusions Despite initiatives such as Getting It Right First Time (GIRFT) and National Institute for Health and Care Excellence (NICE) guidelines, variation still exists between centres with some differences in opinion observed between surgeons and anaesthetists. These differences may be leading to duplication of work in the perioperative pathway, inconsistencies in how risk is assessed and communicated with consequent variation in patient care. Addressing these issues requires awareness and implementation of existing guidelines, transdisciplinary working, efficient data-driven pathways, and structured aortic aneurysm multi-disciplinary team to promote meaningful shared decision-making.

Introduction Thoracic endovascular aortic repair (TEVAR) carries a 3%–6.1% stroke risk, including risk of ‘silent’ cerebral infarction (SCI). Stent-grafts are manufactured in room air and retain air. Instructions for use recommend saline flushing to ‘de-air’ the system prior to insertion, but substantial amounts of air are released when deploying them, potentially leading to downstream neuronal injury and SCI. Carbon dioxide (CO2) is more dense and more soluble in blood than air, without risk of bubble formation, so could be used in addition to saline to de-air stents. This pilot trial aims to assess the feasibility of a full-scale randomised controlled trial (RCT) investigating the neuroprotective benefit against SCI with the use of CO2-flushed aortic stent-grafts.Methods and analysis This is a multicentre pilot RCT, which is taking place in vascular centres in the UK, USA and New Zealand. Patients identified for TEVAR will be enrolled after informed written consent. 120 participants will be randomised (1:1) to TEVAR-CO2 or TEVAR-saline, stratified according to TEVAR landing zone. Participants will undergo preoperative neurocognitive tests and quality of life assessments, which will be repeated at 6 weeks, or first outpatient appointment, and 6 months. Inpatient neurological testing will be performed within 48 hours of return to level 1 care for clinical stroke or delirium. Diffusion-weighted MRI will be undertaken within 72 hours postoperatively (1–7 days) and at 6 months to look for evidence and persistence of SCI. Feasibility will be assessed via measures of recruitment and retention, informing the design of a full-scale trial.Ethics and dissemination The study coordination centre has obtained approval from the London Fulham Research Ethics Committee (19/LO/0836) and Southern Health and Disability Ethics Committee (NZ) and UK’s Health Regulator Authority (HRA). The study has received ethical approval for recruitment in the UK (Fulham REC, 19/LO/0836), New Zealand (21/STH/192) and the USA (IRB 019-264, Ref 378630). Consent for entering into the study will be taken using standardised consent forms by the local study team, led by a local PI. The results of the trial will be submitted for publication in an open access journal.Trial registration number NCT03886675

Pulswidth modulation (PWM) methods were developed to grant the voltage source inverter (VSI) output signal better quality measures. The PWM method that VSI relies on must consider the utilization of the direct current (DC) source, especially when the drive system works in the overmodulation region. In this paper, different zero-sequence harmonic injection PWM methods are proposed. Two essential objectives are optimized by minimizing total harmonic distortion and maximizing the DC bus utilization. All schemes’ results are compared with each other and with some of the commonly used PWM schemes. This paper concludes the usage of third, ninth, and fifteenth harmonic injections and any combination of them to reach a new PWM method that overtakes the disadvantages of other methods. Meanwhile, it provides a handy tool to operate VSI optimally. Ultimately, this work concludes to what extent is the zero-sequence injection is helpful. The work is evaluated experimentally, and the practical results match the simulation outcomes.

Objectives: Inadequate removal of the hemostatic agent can adversely affect the bond strength of restorations to the tooth structure. This study aimed to assess the effect of different cleansing protocols on the shear bond strength (SBS) of an etch-and-rinse adhesive to dentin contaminated with aluminum chloride hemostatic agent. Materials and Methods: In this experimental study, the mid-coronal dentin of 96 premolars was exposed. They were contaminated with a hemostatic agent (ViscoStat Clear) and then randomly divided into 7 groups (n=12). One group served as the control. The groups underwent various cleaning methods as follows: water spray, aluminum oxide particles (27µ diameter), a slurry of pumice with water, GC dentin conditioner (GCDC), sodium hypochlorite 2% (SHC), and chlorhexidine 2% (CHX). Composite cylinders were then fabricated and bonded to the surfaces using Scotchbond Multi-Purpose etch-and-rinse bonding agent. After thermocycling (10,000 cycles), the SBS was measured using a universal testing machine. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey HSD (honestly significant difference) test, and the significance level was set at 0.05. Results: The SBS of the groups was significantly different (P=0.036). The SBS was the highest in the CHX and SHC groups, and the lowest SBS was related to the control group and GCDC groups. The difference between other groups was not significant (P=0.996). Conclusion: CHX and SHC yielded the highest bond strength among the tested modalities for cleansing the ViscoStat Clear from the tooth surface.

Starting from the perspective of the new social studies of childhood and their strong focus on agency of children this article follows the critical voices on the agency concept and reconceptualises children’s autonomy under conditions of vulnerability. Within the adult dominated field of sport the phenomenon of children’s vulnerability as well as children’s autonomy can be seen and discussed empirically. The authors analyse what and how children’s autonomy is enabled or limited e.g. through organisational aspects or through the superior position of adults. This leads to new findings concerning children’s emotional and physical vulnerability, children’s decisions about leisure time and adult-free spaces as well as the limitation of children’s autonomy. As a conclusion or in the sense of an outlook, thoughts towards theories of professionalism are considered.

In Islam, there are four fundamental factors of social development and change – personality, tradition, accident, and people. The Qur’an says: “Verily never will God change the condition of a people until they change it themselves [with their souls]. (Q-13:11). Therefore, the researcher’s aim is assessing the integration of slamic values in the teaching of martial arts in the youth for them be good followers of Islam thru inculcation in their minds and their behavior the real sense of a true Muslim. Essentially, this study is descriptive, which aimed mainly to serve as an exposition on the Religion, Traditional Culture, and History of the Muslims in the Philippines and their implication relevance to martial arts. The various data collected through in-depth study, interview and observation showed that Islam prepares people to be a fruitful citizen in the society. It also aimed for the total development of man not only in the religious aspect. Thus, Martial arts play a vital role in Islam not just as a means of self-defense, but as a system of ethics. Man and fighting are by nature intimately related; in fact, history shows that they are inseparable. Locally, the Bangsamoro has a very rich historical foundation in martial arts that is directly derivable from the roots of Islamic propagation. And as man became civilized, hand-to-hand fighting also became specialized and humanized and, gradually.

Muslim communities are known to be united, but every year, towards the start of Ramadhan, some of them argue which started to be divided over the issue on the determination of the start of the blessed month. This study aimed to investigate the different options proposed for the determination of the month of Ramadhan including local and global sighting; Number of witnesses required; Size of Matla'; and Saudi Sighting Process and its implications. Data were gathered through an in-depth study using the descriptive method. The objectives were to determine the universally accepted legal opinion on sighting the New Moon in connection with the elimination of differences that frequently surface and for ensuring the celebration of 'Eid on a single day in one lunar unit. Based on the findings, it is revealed that sighting the new moon must be conducted in each locality because there are Multiple Horizons (the time at which the moon rises, varies from place to place). Muslims must show unity during the month of Ramadhan and at the occasions of 'Eid at least locally if not nationally or internationally. This would be of great value and importance to the whole Muslim nation by fostering the initial steps towards united observance of Ramadhan.

One crucial barrier to progress in the treatment of cancer has been the inability to control the balance between cell proliferation and apoptosis: enter ceramide. Discoveries over the past 15 years have elevated this sphingolipid to the lofty position of a regulator of cell fate. Ceramide, it turns out, is a powerful tumour suppressor, potentiating signalling events that drive apoptosis, autophagic responses and cell cycle arrest. However, defects in ceramide generation and metabolism in cancer cells contribute to tumour cell survival and resistance to chemotherapy. This Review focuses on ceramide signalling and the targeting of specific metabolic junctures to amplify the tumour suppressive activities of ceramide. The potential of ceramide-based therapeutics in the treatment of cancer is also discussed. [ABSTRACT FROM AUTHOR]

Background: Repair bond strength of different composite resins has been assessed in few studies. In addition, reports on the efficacy of surface treatments are debated. Therefore, this in vitro study was conducted to evaluate the effect of three surface treatments on two nanocomposites versus a microhybrid composite. Materials and Methods: In this experimental study, 135 composite blocks (45 specimens per composite) of microhybrid (Filtek Supreme Z250, 3M ESPE, USA), nanohybrid (Filtek Supreme XT, 3M ESPE), and nanofilled (Filtek Supreme Z350, 3M ESPE) were thermocycled (5000 rounds) and then surface roughened (except in a control group of 9 specimens of three composite types). Each composite type was divided into three subgroups of surface treatments: (1) Bur abrading and phosphoric acid (PA) etching, (2) sandblasting and PA etching, and (3) hydrofluoric etching and silane application (n = 15 × 9, complying with ISO TR11405). Composite blocks were repaired with the same composite type but of a different color. Microtensile bond strength and modes of failure were analyzed statistically using two-way analyses of variance, Tukey and Chi-square tests (α = 0.05). Results: There were significant differences between three composite resins (P < 0.0001) and treatment techniques (P < 0.0001). Their interaction was nonsignificant (P = 0.228). The difference between nanofilled and nanohybrid was not significant. However, the microhybrid composite showed a significantly higher bond strength (Tukey P < 0.05). Sandblasting was significantly superior to the other two methods, which were not different from each other. Conclusion: Within the limitations of this in vitro study, it seems that microhybrid composite might have higher repair strengths than two evaluated nanocomposites. Among the assessed preparation techniques, sandblasting followed by PA etching might produce the highest bond strength.

This study evaluated the types of gene action governing the inheritance of resistance to Phytophthora nicotianae necrosis in populations derived from two crosses involving two susceptible (Beldi and Nabeul II) and one resistant (CM334) cultivars of pepper (Capsicum annuum L.). Populations, composed of Pr, Ps, F1,F2,BC1Pr, and BC1Ps generations, were inoculated with six P. nicotianae isolates. Generation means analysis indicated that an additive-dominance model was appropriate for P. nicotianae isolates PnKo1,PnKo2 and PnKr1, which showed low aggressiveness in the two crosses. For the more aggressive isolates PnBz1,PnBz2 and PnKr2, epistasis was an integral component of resistance in the two crosses. The presence of epistasis in the resistance of pepper to P. nicotianae was dependent on the level of aggressiveness of the isolates. Selection in pepper with less aggressive isolates was efficient, but not with more aggressive isolates; on the other hand, selection with more aggressive isolates was more stable. The minimum number of genes controlling resistance was estimated at up to 2.71. In the majority of cases, the additive variance was significant and greater than the environmental and dominance variance.

Le pseudo-Meigs syndrome comprend une tumeur pelvienne bénigne (en dehors des fibrothécomes ovariens) ou maligne associée à des épanchements, pleural et ou péritonéal, qui disparaissent après l'exérèse tumorale. Nous rapportons l'observation d'une patiente âgée de 47 ans, qui présentait une pleurésie droite associée à une ascite et une tumeur ovarienne maligne. L'évolution après l'exérèse chirurgicale de la masse tumorale même en l'absence d'une chimiothérapie montrait une disparition des épanchements. Le pseudo-Meigs syndrome est rare. Il nécessite des biopsies pleurales et péritonéales négatives, et la disparition des épanchements après l'exérèse chirurgicale de la tumeur, avant toute chimiothérapie. Une telle distinction est importante aussi bien sur le plan thérapeutique que pronostique.

Introduction Workplace violence is a common problem that is encountered by healthcare workers worldwide; however, it is still under-studied in Saudi Arabia. This study aims to determine the prevalence of workplace violence and to explore reasons for not reporting it among healthcare workers in a tertiary medical city in Riyadh. Methods This cross-sectional study was conducted among 404 healthcare workers who had direct contact with patients or their relatives in a tertiary care medical city in Riyadh, Saudi Arabia. Data were analyzed using Statistical Analysis Software Package (SPSS; IBM, Armonk, NY, USA). Results Most participants (81.4%) had experienced verbal, physical, academic, or sexual violence. Approximately 39.6% of those who experienced workplace violence did not report the incident, and the most common reason for not reporting was identified as "reporting would not accomplish anything" (49.4%). About 27.5% of violence victims did not know how to report the incidents. Patients or their relatives were the main sources of violence across all violence categories except academic violence, in which consultant physicians were the main source. Conclusions The prevalence of workplace violence in the population studied was higher than anticipated compared to similar studies both in Saudi Arabia and globally. Almost half of those who were subjected to violence did not report the incident, believing that reporting would not change anything. There is arguably an urgent need to develop strategies that reduce workplace violence and facilitate reporting it in hospitals. Moreover, awareness programs regarding the negative impacts of violence against healthcare workers on the quality of care are necessary., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2021, Alharbi et al.)

There is an urgent unmet need for new therapeutics in acute myeloid leukemia (AML) as standard therapy has not changed in the past three decades and outcome remains poor for most patients. Sphingolipid dysregulation through decreased ceramide levels and elevated sphingosine 1-phosphate (S1P) promotes cancer cell growth and survival. Acid ceramidase (AC) catalyzes ceramide breakdown to sphingosine, the precursor for S1P. We report for the first time that AC is required for AML blast survival. Transcriptome analysis and enzymatic assay show that primary AML cells have high levels of AC expression and activity. Treatment of patient samples and cell lines with AC inhibitor LCL204 reduced viability and induced apoptosis. AC overexpression increased the expression of anti-apoptotic Mcl-1, significantly increased S1P and decreased ceramide. Conversely, LCL204 induced ceramide accumulation and decreased Mcl-1 through post-translational mechanisms. LCL204 treatment significantly increased overall survival of C57BL/6 mice engrafted with leukemic C1498 cells and significantly decreased leukemic burden in NSG mice engrafted with primary human AML cells. Collectively, these studies demonstrate that AC plays a critical role in AML survival through regulation of both sphingolipid levels and Mcl-1. We propose that AC warrants further exploration as a novel therapeutic target in AML.

Colorectal cancer (CRC) is highly metastatic, significantly so to liver, a characteristic that embodies one of the most challenging aspects of treatment. The integrin family of cell-cell and cell-matrix adhesion receptors plays a central role in migration and invasion, functions that underlie metastatic potential. In the present work we sought to determine the impact of ceramide, which plays a key modulatory role in cancer suppression, on integrin cell surface expression and function in CRC cells in order to reveal possible ceramide-centric effects on tumor cell motility. Human CRC cells LoVo, HT-29, and HCT-116 were employed, which represent lines established from primary and metastatic sites. A cell-permeable, short-chain analog, C6-ceramide, was used as ceramide mimic. Exposure of cells to C6-ceramide (24 h) promoted a dose-dependent (2.5-10 µM) decrease in the expression of cell surface β1 and β4 integrin subunits in all cell lines; at 10 µM C6-ceramide, the decreases ranged from 30 to 50% of the control. Expression of cell surface αVβ6 integrin, which is associated with advanced invasion in CRC, was also suppressed by C6-ceramide. Decreases in integrin expression translated to diminished cellular adhesion, 50% of the control at 5 µM C6-ceramide, and markedly reduced cellular migration, approximately 30-40% of the control in all cell lines. Physicochemical examination revealed potent efficacy of nano-formulated C6-ceramide, but inferior activity of dihydro-C6-ceramide and L-C6-ceramide, compared to the unsaturated counterpart and the natural d-enantiomer, respectively. These studies demonstrate novel actions of ceramides that may have application in suppression of tumor metastasis, in addition to their known tumor suppressor effects., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

The objective of our study was to determine the mechanism of action of the short-chain ceramide analog, C6-ceramide, and the breast cancer drug, tamoxifen, which we show coactively depress viability and induce apoptosis in human acute myelogenous leukemia cells. Exposure to the C6-ceramide-tamoxifen combination elicited decreases in mitochondrial membrane potential and complex I respiration, increases in reactive oxygen species (ROS), and release of mitochondrial proapoptotic proteins. Decreases in ATP levels, reduced glycolytic capacity, and reduced expression of inhibitors of apoptosis proteins also resulted. Cytotoxicity of the drug combination was mitigated by exposure to antioxidant. Cells metabolized C6-ceramide by glycosylation and hydrolysis, the latter leading to increases in long-chain ceramides. Tamoxifen potently blocked glycosylation of C6-ceramide and long-chain ceramides. N-desmethyltamoxifen, a poor antiestrogen and the major tamoxifen metabolite in humans, was also effective with C6-ceramide, indicating that traditional antiestrogen pathways are not involved in cellular responses. We conclude that cell death is driven by mitochondrial targeting and ROS generation and that tamoxifen enhances the ceramide effect by blocking its metabolism. As depletion of ATP and targeting the "Warburg effect" represent dynamic metabolic insult, this ceramide-containing combination may be of utility in the treatment of leukemia and other cancers., (Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.)

Fenretinide, N-(4-hydroxyphenyl)retinamide, (4-HPR), a synthetic retinoid, owes its cancer-toxic effects in part to the generation of ceramide, a potent tumor-suppressing sphingolipid. As such, 4-HPR has garnered considerable interest as a chemotherapeutic. Cancer cells, however, via various metabolic routes, inactivate ceramide, and this can limit 4-HPR efficacy. As relatively little is known regarding 4-HPR-induced ceramide management in acute myelogeneous leukemia (AML), we undertook the present study to evaluate the impact of 4-HPR on ceramide production, metabolism, and cytotoxicity. In KG-1, HL-60, and HL-60/VCR (multidrug resistant) human leukemia cells, 4-HPR induced 15-, 2-, and 20-fold increases in ceramide (measured using [3H]palmitic acid), respectively. By use of specific inhibitors we show that ceramide was produced by sphingomyelinase and de novo pathways in response to 4-HPR exposure. HL-60/VCR cells metabolized ceramide to glucosylceramide (GC). 4-HPR exposure (1.25-10 μM) reduced viability in all cell lines, with approximate IC50's ranging from 1 to 8.0 μM. Reactive oxygen species (ROS) were generated in response to 4-HPR treatment, and the concomitant cytotoxicity was reversed by addition of vitamin E. 4-HPR was not cytotoxic nor did it elicit ceramide formation in K562, a chronic myeloid leukemia cell line; however, K562 cells were sensitive to a cell-deliverable form of ceramide, C6-ceramide. Treatment of Molt-3, an acute lymphoblastic leukemia cell line, with 4-HPR revealed moderate ceramide production (5-fold over control), robust conversion of ceramide to GC and sphingomyelin, and resistance to 4-HPR and C6-ceramide. In conclusion, this work demonstrates diversity within and among leukemia in 4-HPR sensitivity and ceramide generation and subsequent metabolism. As such, knowledge of these metabolic pathways can provide guidance for enhancing ceramide-driven effects of 4-HPR in treatment of leukemia., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Tamoxifen, a triphenylethylene antiestrogen and one of the first-line endocrine therapies used to treat estrogen receptor-positive breast cancer, has a number of interesting, off-target effects, and among these is the inhibition of sphingolipid metabolism. More specifically, tamoxifen inhibits ceramide glycosylation, and enzymatic step that can adventitiously support the influential tumor-suppressor properties of ceramide, the aliphatic backbone of sphingolipids. Additionally, tamoxifen and metabolites N-desmethyltamoxifen and 4-hydroxytamoxifen, have been shown to inhibit ceramide hydrolysis by the enzyme acid ceramidase. This particular intervention slows ceramide destruction and thereby depresses formation of sphingosine 1-phosphate, a mitogenic sphingolipid with cancer growth-promoting properties. As ceramide-centric therapies are becoming appealing clinical interventions in the treatment of cancer, agents like tamoxifen that can retard the generation of mitogenic sphingolipids and buffer ceramide clearance via inhibition of glycosylation, take on new importance. In this review, we present an abridged, lay introduction to sphingolipid metabolism, briefly chronicle tamoxifen's history in the clinic, examine studies that demonstrate the impact of triphenylethylenes on sphingolipid metabolism in cancer cells, and canvass works relevant to the use of tamoxifen as adjuvant to drive ceramide-centric therapies in cancer treatment. The objective is to inform the readership of what could be a novel, off-label indication of tamoxifen and structurally-related triphenylethylenes, an indication divorced from estrogen receptor status and one with application in drug resistance., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The triphenylethylene antiestrogen, tamoxifen, can be an effective inhibitor of sphingolipid metabolism. This off-target activity makes tamoxifen an interesting ancillary for boosting the apoptosis-inducing properties of ceramide, a sphingolipid with valuable tumor censoring activity. Here we show for the first time that tamoxifen and metabolite, N-desmethyltamoxifen (DMT), block ceramide glycosylation and inhibit ceramide hydrolysis (by acid ceramidase, AC) in human acute myelogenous leukemia (AML) cell lines and in AML cells derived from patients. Tamoxifen (1-10 μM) inhibition of AC in AML cells was accompanied by decreases in AC protein expression. Tamoxifen also depressed expression and activity of sphingosine kinase 1 (SphK1), the enzyme-catalyzing production of mitogenic sphingosine 1-phosphate (S1-P). Results from mass spectroscopy showed that tamoxifen and DMT (i) increased the levels of endogenous C16:0 and C24:1 ceramide molecular species, (ii) nearly totally halted production of respective glucosylceramide (GC) molecular species, (iii) drastically reduced levels of sphingosine (to 9% of control), and (iv) reduced levels of S1-P by 85%, in vincristine-resistant HL-60/VCR cells. The co-administration of tamoxifen with either N-(4-hydroxyphenyl)retinamide (4-HPR), a ceramide-generating retinoid, or a cell-deliverable form of ceramide, C6-ceramide, resulted in marked decreases in HL-60/VCR cell viability that far exceeded single agent potency. Combination treatments resulted in synergistic apoptotic cell death as gauged by increased Annexin V binding and DNA fragmentation and activation of caspase-3. These results show the versatility of adjuvant triphenylethylene with ceramide-centric therapies for magnifying therapeutic potential in AML. Such drug regimens could serve as effective strategies, even in the multidrug-resistant setting., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Acid ceramidase (AC), EC 3.5.1.23, a lysosomal enzyme, catalyzes the hydrolysis of ceramide to constituent sphingoid base, sphingosine, and fatty acid. Because AC regulates the levels of pro-apoptotic ceramide and mitogenic sphingosine-1-phosphate, it is considered an apt target in cancer therapy. The present study reveals, for the first time, that the prominent antiestrogen, tamoxifen, is a pan-effective AC inhibitor in the low, single digit micromolar range, as demonstrated in a wide spectrum of cancer cell types, prostate, pancreatic, colorectal, and breast. Prostate cancer cells were chosen for the detailed investigations. Treatment of intact PC-3 cells with tamoxifen produced time- and dose-dependent inhibition of AC activity. Tamoxifen did not impact cell viability nor did it inhibit AC activity in cell-free assays. In pursuit of mechanism of action, we demonstrate that tamoxifen induced time-, as early as 5min, and dose-dependent, as low as 5μM, increases in lysosomal membrane permeability (LMP), and time- and dose-dependent downregulation of AC protein expression. Assessing various protease inhibitors revealed that a cathepsin B inhibitor blocked tamoxifen-elicited downregulation of AC protein; however, this action failed to restore AC activity unless assayed in a cell-free system at pH4.5. In addition, pretreatment with tamoxifen inhibited PC-3 cell migration. Toremifene, an antiestrogen structurally similar to tamoxifen, was also a potent inhibitor of AC activity. This study reveals a new, off-target action of tamoxifen that may be of benefit to enhance anticancer therapies that either incorporate ceramide or target ceramide metabolism., (© 2013.)

Poor prognosis in patients with later stage colorectal cancer (CRC) necessitates the search for new treatment strategies. Ceramide, because of its role in orchestrating death cascades in cancer cells, is a versatile alternative. Ceramide can be generated by exposure to chemotherapy or ionizing radiation, or it can be administered in the form of short-chain analogs (C6-ceramide). Because intracellular P-glycoprotein (P-gp) plays a role in catalyzing the conversion of ceramide to higher sphingolipids, we hypothesized that administration of P-gp antagonists with C6-ceramide would magnify cell death cascades. Human CRC cell lines were employed, HCT-15, HT-29, and LoVo. The addition of either tamoxifen, VX-710, verapamil, or cyclosporin A, antagonists of P-gp, enhanced C6-ceramide cytotoxicity in all cell lines. In depth studies with C6-ceramide and tamoxifen in LoVo cells showed the regimen induced PARP cleavage, caspase-dependent apoptosis, mitochondrial membrane permeabilization (MMP), and cell cycle arrest at G1 and G2. At the molecular level, the regimen, but not single agents, induced time-dependent upregulation of tumor suppressor protein p53; however, introduction of a p53 inhibitor staved neither MMP nor apoptosis. Nanoliposomal formulations of C6-ceramide and tamoxifen were also effective, yielding synergistic cell kill. We conclude that tamoxifen is a favorable adjuvant for enhancing C6-ceramide cytotoxicity in CRC, and demonstrates uniquely integrated effects. The high frequency of expression of P-gp in CRC presents an adventitious target for complementing ceramide-based therapies, a strategy that could hold promise for treatment of resistant disease., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Purpose: Acid ceramidase (AC) occupies an important place in the control of cancer cell proliferation. We tested the influence of AC inhibition on the effects of PSC 833, a P-glycoprotein antagonist with potent ceramide-generating capacity, to determine whether AC could be a therapeutic target in pancreatic cancer., Methods: Ceramide metabolism was followed using (3)H-palmitate, and molecular species were determined by mass spectroscopy. Apoptosis was measured by DNA fragmentation, autophagy by acridine orange staining, and cell cycle was assessed by flow cytometry and RB phosphorylation. AC was measured in intact cells using fluorescent substrate., Results: Exposure of human PANC-1 or MIA-PaCa-2 cells to PSC 833 promoted increases in de novo (dihydro)ceramides, (dihydro)glucosylceramides, and (dihydro)sphingomyelins, demarking ceramide generation and robust metabolism. Despite the multifold increases in (dihydro)ceramide levels, cells were refractory to PSC 833. However, PSC 833 produced a dose-dependent decrease in DNA synthesis and dose- and time-dependent decreases in RB phosphorylation, consistent with cell cycle arrest as demonstrated at G1. Cytostatic effects of PSC 833 were converted to cytotoxic end-point by acid ceramidase inhibition. Cytotoxicity was accompanied by formation of acridine orange-stained acidic vesicles and an increase in LC3 expression, indicative of autophagic response. Cell death was not reversed by preexposure to myriocin, which blocks PSC 833-induced ceramide generation., Conclusion: Although the role of ceramide in end-point cytotoxicity is unclear, our results suggest that acid ceramidase is a viable target in pancreatic cancer. We propose that AC inhibition will be effective in concert with other anticancer therapies.

The mammalian target of rapamycin (mTOR) is a key regulator of cell growth and its uncontrolled activation is a hallmark of cancer. Moreover, mTOR activation has been implicated in the resistance of cancer cells to many anticancer drugs, rendering this pathway a promising pharmacotherapeutic target. Here we explored the capability of a semisynthetic compound to intercept mTOR signaling. We synthesized and chemically characterized a novel, semisynthetic triterpenoid derivative, 3-cinnamoyl-11-keto-β-boswellic acid (C-KβBA). Its pharmacodynamic effects on mTOR and several other signaling pathways were assessed in a number of prostate and breast cancer cell lines as well as in normal prostate epithelial cells. C-KβBA exhibits specific antiproliferative and proapoptotic effects in cancer cell lines in vitro as well as in PC-3 prostate cancer xenografts in vivo. Mechanistically, the compound significantly inhibits the cap-dependent transition machinery, decreases expression of eukaryotic translation initiation factor 4E and cyclin D1, and induces G(1) cell-cycle arrest. In contrast to conventional mTOR inhibitors, C-KβBA downregulates the phosphorylation of p70 ribosomal S6 kinase, the major downstream target of mTOR complex 1, without concomitant activation of mTOR complex 2/Akt and extracellular signal-regulated kinase pathways, and independently of protein phosphatase 2A, liver kinase B1/AMP-activated protein kinase/tuberous sclerosis complex, and F12-protein binding. At the molecular level, the compound binds to the FKBP12-rapamycin-binding domain of mTOR with high affinity, thereby competing with the endogenous mTOR activator phosphatidic acid. C-KβBA represents a new type of proapoptotic mTOR inhibitor that, due to its special mechanistic profile, might overcome the therapeutic drawbacks of conventional mTOR inhibitors.

Gaucher's disease is a sphingolipidosis characterized by a specific deficiency in an acidic glucocerebrosidase, which results in aberrant accumulation of glucosylceramide primarily within the lysosome. Gaucher's disease has been correlated with cases of myeloma, leukemia, glioblastoma, lung cancer, and hepatocellular carcinoma, although the reasons for the correlation are currently being debated. Some suggest that the effects of Gaucher's disease may be linked to cancer, while others implicate the therapies used to treat Gaucher's disease. This debate is not entirely surprising, as the speculations linking Gaucher's disease with cancer fail to address the roles of ceramide and glucosylceramide in cancer biology. In this review, we will discuss, in the context of cancer biology, ceramide metabolism to glucosylceramide, the roles of glucosylceramide in multidrug-resistance, and the role of ceramide as an anticancer lipid. This review should reveal that it is most practical to associate elevated glucosylceramide, which accompanies Gaucher's disease, with the progression of cancer. Furthermore, this review proposes that the therapies used to treat Gaucher's disease, which augment ceramide accumulation, are likely not linked to correlations with cancer.

Although the sphingolipid ceramide exhibits potent tumor suppressor effects, efforts to harness this have been hampered by poor solubility, uptake, bioavailability, and metabolic conversion. Therefore, identification of avenues to improve efficacy is necessary for development of ceramide-based therapies. In this study, we used mutant p53, triple-negative breast cancer (TNBC) cells, a type of breast cancer highly refractory to treatment, and cell-permeable nanoliposomal C6-ceramide in conjunction with the antiestrogen tamoxifen, which has been shown to be an effective modulator of ceramide metabolism. We show for the first time that nanoliposomal tamoxifen enhances nanoliposomal C6-ceramide cytotoxicity in cultured TNBC cells, a response that was accompanied by induction of cell-cycle arrest at G(1) and G(2), caspase-dependent induction of DNA fragmentation, and enhanced mitochondrial and lysosomal membrane permeability at 18 and 2 hours, respectively. Tamoxifen metabolites were also effective. Only tamoxifen promoted lysosomal membrane permeability. In addition, we show for the first time that tamoxifen inhibits acid ceramidase, as measured in intact cell assays; this effect was irreversible. Together, our findings show that tamoxifen magnifies the antiproliferative effects of C6-ceramide via combined targeting of cell-cycle traverse and lysosomal and mitochondrial integrity. We adduce that C6-ceramide-induced apoptosis is amplified by tamoxifen's impact on lysosomes and perhaps accompanying inhibition of acid ceramidase, which could result in decreased levels of sphingosine 1-phosphate. This drug regimen could serve as a promising therapy for chemoresistant and triple-negative types of breast cancer, and thus represents an indication for tamoxifen, irrespective of estrogen receptor status., (©2012 AACR.)

Mastic, a resinous exudate from Pistacia lentiscus, has been reported to exhibit selective cytotoxicity against different cancer cell lines. There are, however, no data published correlating distinct mastic-derived compounds with the postulated cytotoxic activity. A polypodane-type bicyclic triterpenoid, (8R)-3β,8-dihydroxypolypoda-13E,17E,21-triene (1), was isolated from P. lentiscus oleogum resin. In androgen-independent PC-3 prostate cancer cells, 1 potently inhibited the expression of cyclins D1 and E, but had no effect on the expression of the cyclin kinase inhibitor p21(Waf1/Cip1). Inhibition of the expression of cell cycle-regulating cyclins resulted in cell cycle arrest in the G₀/G₁ phase, reduction in the number of cells in the S phase, and the triggering of apoptosis, as detected by increased expression of phosphatidylserine on the cell surface and by formation of DNA laddering. In addition, 1 suppressed the formation of prostate cancer colonies in soft agar and inhibited proliferation, angiogenesis, and the growth of prostate tumors xenografted onto chick chorioallantoic membranes without overt systemic toxicity. Taken together, these data show that 1 triggers apoptosis in chemoresistant, androgen-independent human prostate cancer cells in vitro and in vivo. Thus, 1 may serve as a lead compound for targeting so far incurable androgen-insensitive prostate cancers.

Activation of the serine/threonine kinase Akt is associated with aggressive clinical behavior of prostate cancer. We found that the human prostate cancer cell lines LNCaP and PC-3 express predominantly Akt1 and Akt2. Selective down-regulation of Akt1, but not Akt2, by short-hairpin RNA reduced the viability of prostate cancer cells. In addition, structurally different Akt inhibitors were cytotoxic for the prostate cancer cells, confirming that the Akt pathway is indispensable for their viability. We have purified the tetracyclic triterpenoids 3-oxo-tirucallic acid, 3-alpha-acetoxy-tirucallic acid, and 3-beta-acetoxy-tirucallic acid from the oleogum resin of Boswellia carterii to chemical homogeneity. The acetoxy-derivatives in particular potently inhibited the activities of human recombinant Akt1 and Akt2 and of constitutively active Akt immunoprecipitated from PC-3 cells, whereas inhibitor of nuclear factor-kappaB kinases remained unaffected. Docking data indicated that these tetracyclic triterpenoids form hydrogen bonds within the phosphatidylinositol binding pocket of the Akt pleckstrin homology domain. Accordingly, 3-beta-acetoxy-tirucallic acid did not inhibit the activity of Akt1 lacking the pleckstrin homology domain. In the prostate cancer cell lines investigated, these compounds inhibited the phosphorylation of cellular Akt and the Akt signaling pathways, including glycogen synthase kinase-3beta and BAD phosphorylation, nuclear accumulation of p65, the androgen receptor, beta-catenin, and c-Myc. These events culminated in the induction of apoptosis in prostate cancer, but not in nontumorigenic cells. The tirucallic acid derivatives inhibited proliferation and induced apoptosis in tumors xenografted onto chick chorioallantoic membranes and decreased the growth of pre-established prostate tumors in nude mice without overt systemic toxicity. Thus, tirucallic acid derivatives represent a new class of Akt inhibitors with antitumor properties.