Maslinic acid inhibits the metastatic capacity of DU145 human prostate cancer cells: possible mediation via hypoxia-inducible factor-1α signalling

Chemical profiling, bio-guided purification, and cytotoxic effect of two African spices: Hypodaphnis zenkeri Engl. Stapf (Lauraceae) and Staudtia kamerunensis warb (Myristicaceae) on human prostate cancer cell lines

ETHNOPHARMACOLOGICAL RELEVANCE

Prostate cancer remains a significant burden in low- and middle-income countries and the second leading cause of death around the world. Spices used in daily cuisine contain interesting phytochemical components capable of helping prevent and cure cancer.

AIM

This study aims to give sufficient phytochemical information on two understudied species, Staudtia kamerunensis Warb. (Myristicaceae) and Hypodaphnis zenkeri Engl. Stapf. (Lauraceae), and to study their cytotoxicity against prostate cancer cells in its early form and when they have developed metastasis.

MATERIALS AND METHODS

To reach this goal, normal procedures for phytochemical analysis were followed; these include collection, drying, crushing and extraction of plant materials using organic solvents. GC-MS (Gas chromatography- Mass Spectrometry) was used to evaluate the volatile phytochemicals contained in the extracts, and open-column chromatography was used to isolate the pure compounds used in this study. A bio-guided exploration of Hypodaphnis zenkeri (Lauraceae) (leaves, seeds, stems) guided us in selecting the extract for further analysis. An established MTT assay was used to measure cell proliferation. Three prostate cancer cell lines were considered in this study, DU145 and PC3, human androgens-independent prostate carcinoma cells and LNCaP, which are cells derived from metastasis of a human prostate and respond to androgens, oestrogens and progestins. The eight compounds isolated were characterized using HREIMS, 1D and 2D NMR.

RESULTS

Among the three extracts from Hypodaphnis zenkeri, considered for biological testing, the leaf extract displayed better activities with a CC50 of 180 μg/mL against DU 145 cells, 184 μg/mL against PC3 cells and 194 μg/mL against LNCaP cells. These results were justified when GC-MS analysis of the different extracts was performed. Fifty compounds were identified from the leaves, representing 96.06% of the volatile components, with most displaying anticancer activities or activities against vectors favorizing cancer growth (inflammation, etc.). An attempt to isolate the active principle responsible for the cancer activity led to the isolation of five pure compounds, namely Eicosane [1], Nonacos-1-ene [2], Palmitic acid [3], Glucoside Stigmasterol [4] and Butane-1,2,3,4-tetraol [5]. Eicosane was identified as being responsible in part for the observed activity, even though it exhibited weak cytotoxicity with the lowest CC50 equal to 30 μg/mL against DU 145 cells. Staudtia kamerunensis sap was investigated in our previous studies with the isolation of Oleanan-12-ene-2α,3β -diol [6] and 2α, 3β -dihydroxylup-20-ene [7] among the major components, with significant antibacterial properties. Oleanan-12-ene-2α,3β -diol [7] in this study displayed a CC50 of 20 μg/mL against DU145 cells, 22 μg/mL against PC3 cells, 18 μg/mL against LNCaP cells, and 32 μg/mL in HMEC affording a selectivity index >2. Contrary to what was observed in our previous study, the activity of Oleanan-12-ene-2α,3β -diol was lost in the presence of 2α, 3β -dihydroxylup-20-ene.

CONCLUSION

the cytotoxic effect of extract from Staudtia and Hypodaphnis genera and pure isolates are here reported for the first time, as well as the pure isolates. These studies exhibit the cytotoxic potential of two traditional African spices and, more specifically, Oleanan-12-ene-2α,3β -diol and eicosane, isolated from these plant species.

Bioactivities and Structure-Activity Relationships of Maslinic Acid Derivatives: A Review

Maslinic acid has a variety of biological activities, such as anti-tumor, hypoglycemic, anti-inflammatory, and anti-parasitic. In order to enhance the biological activity of maslinic acid, scholars have carried out a lot of structural modifications, and found some more valuable maslinic acid derivatives. In this paper, the structural modification, biological activity, and structure-activity relationship of maslinic acid were reviewed, providing references for the development of maslinic acid.

Maslinic acid exerts anticancer effects by targeting cancer hallmarks

BACKGROUND

Natural products have long been regarded as a source of anticancer compounds with low toxicity. Evidence revealed that maslinic acid (MA), a widely distributed pentacyclic triterpene in common foodstuffs, exhibited pronounced inhibitory effects against various cancer cell lines. Most cancer cells thrive by acquiring cancer hallmarks, as coined by Hanahan and Weinberg in 2000 and 2011.

PURPOSE

This represents the first systematic review concerning the anticancer properties of MA as these cancer hallmarks are targeted. It aims to summarize the antineoplastic activities of MA, discuss the diverse mechanisms of action based on the effects of MA exerted on each hallmark.

METHODS

A comprehensive literature search was conducted using the search terms "maslinic," "cancer," "tumor," and "neoplasm," to retrieve articles from the databases MEDLINE, EMBASE, Web of Science, and Scopus published up to September 2022. Study selection was conducted by three reviewers independently from title and abstract screening until full-text evaluation. Data extraction was done by one reviewer and counterchecked by the second reviewer.

RESULTS

Of the 330 articles assessed, 40 papers met the inclusion criteria and revealed that MA inhibited 16 different cancer cell types. MA impacted every cancer hallmark by targeting multiple pathways.

CONCLUSION

This review provides insights regarding the inhibitory effects of MA against various cancers and its remarkable biological properties as a pleiotropic bioactive compound, which encourage further investigations.

Maslinic Acid: A New Compound for the Treatment of Multiple Organ Diseases

Maslinic acid (MA) is a pentacyclic triterpene acid, which exists in many plants, including olive, and is highly safe for human beings. In recent years, it has been reported that MA has anti-inflammatory, antioxidant, anti-tumor, hypoglycemic, neuroprotective and other biological activities. More and more experimental data has shown that MA has a good therapeutic effect on multiple organ diseases, indicating that it has great clinical application potential. In this paper, the extraction, purification, identification and analysis, biological activity, pharmacokinetics in vivo and molecular mechanism of MA in treating various organ diseases are reviewed. It is hoped to provide a new idea for MA to treat various organ diseases.

Maslinic Acid Inhibits the Growth of Malignant Gliomas by Inducing Apoptosis via MAPK Signaling

Background

Gliomas are primary malignant brain tumors. Despite recent advances in surgery and clinical neuro-oncology, the prognosis of patients with glioma is still poor. Therefore, there is an urgent need to find new therapeutic drugs.

Methods

Here, we have studied the anticancer effect of maslinic acid in glioma and explored its potential molecular mechanism. CCK-8, Ki67 immunofluorescence, and colony formation tests are used to detect the proliferation of glioma cells. Transwell and migration experiments are used to detect the function of cell invasion and migration, and RNA-seq was performed to identify differentially expressed genes. Western blot analysis helps us identify important signaling pathways. Finally, the anticancer effect of maslinic acid was confirmed in vivo through tumor xenografting experiments.

Results

Our experiments obtained high-throughput data on the treatment of maslinic acid in glioma. We found that maslinic acid significantly inhibits the proliferation, invasion, and migration of glioma cells and promotes the apoptosis of glioma cells via suppressing MAPK signaling.

Conclusions

This is the first time to analyze the mechanism of maslinic acid against glioma based on transcription. Our experiments show that maslinic acid may be a useful natural product for the treatment of glioma.

Transcriptome and proteome analysis of the antitumor activity of maslinic acid against pancreatic cancer cells

Maslinic acid (MA) is a triterpenoid compound of natural abundance in olive plants possessing numerous biological activities. The effect and molecular mechanism of MA on pancreatic cancer cells remain elusive. Here, we explored the anti-tumor activity of MA on human pancreatic cancer cells and the potential underlying molecular mechanism. The anti-cancer effects of MA on whole-cell processes, including proliferation, migration, and invasion in pancreatic cancer cells, were systematically assessed by colony formation, transwell, and migration assays. The search for potential therapeutic targets was achieved via transcriptomics and proteomics analyses. MA was demonstrated to inhibit the proliferation, migration, and invasion of PANC-1 and Patu-8988 cells, but induced apoptosis of these cells. Several key candidate genes and proteins of functional relevance for the anti-tumor activity of MA were identified through the association analysis of transcriptomics and proteomics. To our knowledge, this is the first transcription and proteomics-based comprehensive analysis of the mechanism of MA against pancreatic cancer. The findings demonstrate that MA holds promise as a therapeutic drug for managing pancreatic cancer.

The Anticancer Potential of Maslinic Acid and Its Derivatives: A Review

Cancer is still an insurmountable problem for humans and critically attacking human health. In recent years, natural products have gained increasing attention in the field of anti-tumor due to their extensive sources and minimal side effects. Maslinic acid (MA), a pentacyclic triterpene acid mainly derived from the olive tree (Olea europaea L.) has been confirmed to possess great anti-cancer effects. This paper reviewed the inhibitory effect of MA and its derivatives on lung cancer, colon cancer, ovarian cancer, gastric cancer, lymphatic, leukemia, breast cancer, pancreatic cancer, melanoma, prostate cancer, renal cell carcinoma, gallbladder cancer, and bladder cancer, among others. MA inhibited the proliferation of various tumor cells and showed lower IC50 values in melanoma 518A2 cells and gastric cancer MKN28 cells compared with other cell lines. A series of semi-synthetic derivatives obtained by modifying MA chemical structure have been shown to have high cytotoxicity to human tumor cell lines, but low cytotoxicity to non-malignant cells, which is conducive to developing its potential as a chemotherapeutic agent. These studies suggest that MA derivatives have broad prospects in the development of antitumor therapeutics in the future and warrant further study.

Maslinic acid differentially exploits the MAPK pathway in estrogen-positive and triple-negative breast cancer to induce mitochondrion-mediated, caspase-independent apoptosis

Breast cancer accounts for 1.4 million new cases every year. Triple-negative breast cancer (TNBC) is one the leading cause of mortality in developing countries and is associated with early age onset (under 40 years old). Chemotherapy has a poor success rate in patients with TNBC as compared to other types of breast cancers. It is due to the lack of expression of three validated molecular markers for breast cancer, the estrogen and progesterone receptors, and the amplification of HER-2/Neu. Therefore, a clear need exists for a greater understanding of TNBC at all levels and for the development of better therapies. We have studied the anti-tumor effects of a potential drug, maslinic acid, which can be extracted from olive oil industry waste. This natural product showed inhibitory effect at concentrations ranging from 30 to 50 µM within 24 h. It exhibited divergent effects in cell cycle progression for the MCF7 (estrogen positive) cell line when compared with TNBCs like MDA-MB-231 and MDA-MB-468. Also, maslinic acid treatment altered the mitochondrial membrane electrochemical potential and the reactive oxygen species (ROS) levels to cause a caspase-independent programmed cell death. In silico approaches and immunoblotting suggested the involvement of the MAPK pathway explaining the variability in cell cycle progression along with the apoptotic cell death caused by maslinic acid.

Assessment of the Antiangiogenic and Anti-Inflammatory Properties of a Maslinic Acid Derivative and its Potentiation using Zinc Chloride

Maslinic acid is a pentacyclic triterpene with a plethora of biological activities, including anti-inflammatory, antioxidant, antimicrobial, cardioprotective, and antitumor effects. New derivatives with improved properties and broad-spectrum activity can be obtained following structural changes of the compound. The present study was aimed to characterize a benzylamide derivative of maslinic acid—benzyl (2α, 3β) 2,3-diacetoxy-olean⁻12-en-28-amide (EM2)—with respect to the anti-angiogenic and anti-inflammatory effects in two in vivo experimental models. Consequently, the compound showed good tolerability and lack of irritation in the chorioallantoic membrane assay with no impairment of the normal angiogenic process during the tested stages of development. In the acute ear inflammation murine model, application of EM2 induced a mild anti-inflammatory effect that was potentiated by the association with zinc chloride (ZnCl₂). A decrease in dermal thickness of mice ears was observed when EM2 and ZnCl₂ were applied separately or in combination. Moreover, hyalinization of the dermis appeared only when EM2 was associated with ZnCl₂, strongly suggesting the role of their combination in wound healing.

Maslinic acid alleviates ischemia/reperfusion-induced inflammation by downregulation of NFκB-mediated adhesion molecule expression

Ischemia/reperfusion (I/R)-induced inflammation is associated with enhanced leukocyte rolling, adhesion and transmigration within the microcirculation. These steps are mediated by hypoxia-triggered signaling pathways, which upregulate adhesion molecule expression on endothelial cells and pericytes. We analyzed whether these cellular events are affected by maslinic acid (MA). Mitochondrial activity and viability of MA-exposed endothelial cells and pericytes were assessed by water-soluble tetrazolium (WST)-1 and lactate dehydrogenase (LDH) assays as well as Annexin V/propidium iodide (PI) stainings. Effects of MA on hypoxia and reoxygenation-induced expression of E-selectin, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 were determined by flow cytometry. The subcellular localization of the NFκB subunit p65 was analyzed by immunofluorescence and Western blot. I/R-induced leukocytic inflammation was studied in MA- and vehicle-treated mouse dorsal skinfold chambers by intravital fluorescence microscopy and immunohistochemistry. MA did not affect viability, but suppressed the mitochondrial activity of endothelial cells. Furthermore, MA reduced adhesion molecule expression on endothelial cells and pericytes due to an inhibitory action on NFκB signaling. Numbers of adherent and transmigrated leukocytes were lower in post-ischemic tissue of MA-treated mice when compared to vehicle-treated controls. In addition, MA affected reactive oxygen species (ROS) formation, resulting in a diminished oxidative DNA damage. Hence, MA represents an attractive compound for the establishment of novel therapeutic approaches against I/R-induced inflammation.

Maslinic Acid Enhances Immune Responses in Leukemic Mice Through Macrophage Phagocytosis and Natural Killer Cell Activities In Vivo

BACKGROUND/AIM

Maslinic acid (MA), a pentacyclic triterpene extracted from wax-like coatings of olives, has been shown to reduce cancer cell number through induction of autophagy and apoptosis in many human cancer cells including human leukemia HL-60 cells. In the present study, we investigated whether or not MA affects immune responses in a leukemia mouse model.

MATERIALS AND METHODS

WEHI-3 cells were intraperitonealIy (i.p.) injected into normal BALB/c mice to develop leukemia. Mice were then treated by i.p. injection with MA at different doses (0, 8, 16 and 32 mg/kg) for 2 weeks. After treatment, all animals were weighed and blood, liver and spleen tissues were weighed. Blood or spleen both were used for determination of cell markers or phagocytosis, natural killer (NK) cell activities and T- and B-cell proliferation, respectively, by using a flow cytometric assay.

RESULTS

MA did not significantly affect body, liver, and spleen weights. However, MA increased markers of T-cells (at 16 mg/kg treatment) and monocytes (at 32 mg/kg treatment), but reduced B-cell markers (at 8 mg/kg treatment); MA did not significantly affect cell marker of macrophages. Furthermore, MA increased phagocytosis by macrophages from peripheral blood mononuclear cells and peritoneal cavity at 32 mg/kg treatment and increased NK cell activity at target cell:splenocyte ratio of 25:1 but did not affect B- and T-cell proliferation.

CONCLUSION

MA increased immune responses by enhancing macrophage phagocytosis and NK cell activities in leukemic mice.

Triterpenoid corosolic acid attenuates HIF-1 stabilization upon cobalt (II) chloride-induced hypoxia in A549 human lung epithelial cancer cells

Hypoxia-inducible factor-1 is a target for the management of cancer. Here, the anti-proliferation properties of corosolic acid (CA) against A549 human lung epithelial cancer cells in CoCl₂-induced hypoxia is reported. CA was isolated from the roots of Salvia syriaca based on a bioassay-guided isolation platform and identified by 1D and 2D NMR experiments. Several cytotoxicies and genotoxicity analyses were performed using MTT, DAPI, cell cycle, DNA ladder, and annexin V/PI detection. Cobalt chloride (CoCl₂) was used to stimulate hypoxia. The adaptation of A549 cells to a stimulated hypoxic condition in the presence of CA was evaluated. CA decreased the growth of A549 cells with an IC₅₀ of 12 μg/mL at 48 h. Also, chromatin condensation and DNA fragmentation were detected as signs of apoptosis occurrence. CA induced ~85% apoptosis and even 1% necrosis. The expression of hypoxia-inducible factor-1 α (HIF-1α), HIF-1β and downstream genes was strongly suppressed in the presence of CA in CoCl₂-stimulated hypoxia condition. Results indicated that CA has remarkable cytotoxicity against the cancerous cell in hypoxia condition and may be regarded for preparation of new formulations for possible uses as supplement and medicine in cancer therapy.

Maslinic acid protects against pressure overload-induced cardiac hypertrophy in mice

Cardiac hypertrophy is characterized by myocyte hypertrophy, accumulation of cardiac collagen, and reactivation of fetal genes. Maslinic acid (MA) is a pentacyclic triterpene with abundance in olive fruit skin and possesses a number of pharmacological actions. However, its effect on pressure overload-induced cardiac hypertrophy remains unknown. Here, we were to investigate the protective effect of MA on cardiac hypertrophy and fibrosis. C57 mice were subjected to aortic banding (AB) or sham surgery. One day after surgery, all the mice were orally given MA (20 mg/kg) or vehicle for the following four weeks. MA could protect against pressure overload-induced cardiac hypertrophy and cardiac fibrosis, as indicated by decreased heart weight/tibia length, and cardiomyocytes cell area and hypertrophic and fibrotic markers. MA treatment also improved cardiac function in mice with AB surgery, as assessed by echocardiographic and hemodynamic analysis. MA reduced phosphorylation of protein kinase B and extracellular regulated protein kinases in the hypertrophic hearts. MA could decrease cardiomyocyte hypertrophy, and inhibit the activation of AKT and ERK signaling pathway in vitro. In conclusion, we found that MA protected against cardiac hypertrophy. MA has the potential to become a therapeutic drug for cardiac hypertrophy.

Phenolic Compounds Isolated from Olive Oil as Nutraceutical Tools for the Prevention and Management of Cancer and Cardiovascular Diseases

Non-communicable diseases (NCDs) have become the largest contributor to worldwide morbidity and mortality. Among them, cancer and cardiovascular diseases (CVDs) are responsible for a 47% of worldwide mortality. In general, preventive approaches modifying lifestyle are more cost-effective than treatments after disease onset. In this sense, a healthy diet could help a range of NCDs, such as cancer and CVDs. Traditional Mediterranean Diet (MD) is associated by the low-prevalence of certain types of cancers and CVDs, where olive oil plays an important role. In fact, different epidemiological studies suggest that olive oil consumption prevents some cancers, as well as coronary heart diseases and stroke incidence and mortality. Historically, the beneficial health effects of virgin olive oil (VOO) intake were first attributed to the high concentration of monounsaturated fatty acids. Nowadays, many studies indicate that phenolic compounds contained in olive oil have positive effects on different biomarkers related to health. Among them, phenolic compounds would be partially responsible for health benefits. The present work aims to explore, in studies published during the last five years, the effects of the main phenolic compounds isolated from olive oil on different cancer or CVD aspects, in order to clarify which compounds have more potential to be used as nutraceuticals with preventive or even therapeutic properties.

Maslinic acid suppresses the growth of human gastric cells by inducing apoptosis via inhibition of the interleukin-6 mediated Janus kinase/signal transducer and activator of transcription 3 signaling pathway

The present study aimed to determine whether maslinic acid effectively inhibits the proliferation of MKN28 cells, and to investigate the mechanisms underlying its antitumor functions. MKN28 cell viability was evaluated using a Cell Counting Kit-8, cell proliferation was analyzed by a colony formation assay and flow cytometry was used to investigate the rate of apoptosis. Western blot analysis was performed in order to determine the differential expression levels of Janus kinase (JAK), signal transducer and activator of transcription 3 (STAT3) and apoptosis associated proteins B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax) and Bcl-2 associated agonist of cell death (Bad). Interleukin-6 (IL-6) concentration was evaluated using ELISA. IL-6 and anti-IL-6 antibodies were used to investigate the role of IL-6 in MKN28 cells treated with maslinic acid proliferation, and the STAT3 phosphorylation rates. The results demonstrated that maslinic acid treatment significantly reduced cell proliferation, induced apoptosis and was accompanied by a significant decrease in Bcl-2, Bax and Bad expression levels. Maslinic acid treatment also resulted in the downregulation of phosphorylated-STAT3 and JAK2, and significantly inhibited the protein expression of IL-6. Maslinic acid is able to inhibit MKN28 cell proliferation and the phosphorylation of STAT3 by downregulating the expression of IL-6. These results suggest that maslinic acid suppresses the growth of MKN28 cells by inducing apoptosis via its inhibition of the IL-6/JAK/STAT3 signaling cascade.

Maslinic Acid Inhibits Proliferation of Renal Cell Carcinoma Cell Lines and Suppresses Angiogenesis of Endothelial Cells

Despite the introduction of many novel therapeutics in clinical practice, metastatic renal cell carcinoma (RCC) remains a treatment-resistant cancer. As red and processed meat are considered risk factors for RCC, and a vegetable-rich diet is thought to reduce this risk, research into plant-based therapeutics may provide valuable complementary or alternative therapeutics for the management of RCC. Herein, we present the antiproliferative and antiangiogenic effects of maslinic acid, which occurs naturally in edible plants, particularly in olive fruits, and also in a variety of medicinal plants. Human RCC cell lines (ACHN, Caki-1, and SN12K1), endothelial cells (human umbilical vein endothelial cell line [HUVEC]), and primary cultures of kidney proximal tubular epithelial cells (PTEC) were treated with maslinic acid. Maslinic acid was relatively less toxic to PTEC when compared with RCC under similar experimental conditions. In RCC cell lines, maslinic acid induced a significant reduction in proliferation, proliferating cell nuclear antigen, and colony formation. In HUVEC, maslinic acid induced a significant reduction in capillary tube formation in vitro and vascular endothelial growth factor. This study provides a rationale for incorporating a maslinic acid–rich diet either to reduce the risk of developing kidney cancer or as an adjunct to existing antiangiogenic therapy to improve efficacy.

Effects of maslinic acid on the proliferation and apoptosis of A549 lung cancer cells

Maslinic acid (MA) is a pentacyclic triterpene acid that is present in numerous dietary plants. Although certain studies have demonstrated that MA has anti-cancer properties in different cell types, the effect of MA on lung cancer cell proliferation and apoptosis and the potential underlying mechanisms remain to be elucidated. In the present study, A549 lung cancer cells were treated with different doses of MA and it was found that MA significantly inhibited A549 cell growth in a dose-dependent manner. In addition, Annexin V/propidium iodide flow cytometric analysis demonstrated that MA induced apoptosis of A549 cells. The present study also confirmed that MA induced apoptosis by observing morphological alterations. In addition, the effect of MA treatment on the levels of apoptosis-associated proteins was examined. The results demonstrated that MA treatment suppressed the expression of caspase-3, -8 and -9, and increased the expression of cleaved caspase-3, -8 and -9 in a dose-dependent manner. The level of inhibitors of apoptosis (IAPs) and Smac, which are possible upstream factors of caspase proteins, were also examined. It was found that MA treatment increased the protein expression of Smac and decreased the protein levels of c-IAP1, c-IAP2, X-linked inhibitor of apoptosis protein (XIAP) and Survivin in a dose-dependent manner. These results suggested that MA inhibited proliferation and induced apoptosis of A549 cells through regulation of caspase cleavage as well as Smac, c-IAP1, c-IAP2, XIAP and Survivin.

Mechanistic Perspectives of Maslinic Acid in Targeting Inflammation

Chronic inflammation drives the development of various pathological diseases such as rheumatoid arthritis, atherosclerosis, multiple sclerosis, and cancer. The arachidonic acid pathway represents one of the major mechanisms for inflammation. Prostaglandins (PGs) are lipid products generated from arachidonic acid by the action of cyclooxygenase (COX) enzymes and their activity is blocked by nonsteroidal anti-inflammatory drugs (NSAIDS). The use of natural compounds in regulation of COX activity/prostaglandins production is receiving increasing attention. In Mediterranean diet, olive oil and table olives contain significant dietary sources of maslinic acid. Maslinic acid is arising as a safe and novel natural pentacyclic triterpene which has protective effects against chronic inflammatory diseases in various in vivo and in vitro experimental models. Understanding the anti-inflammatory mechanism of maslinic acid is crucial for its development as a potential dietary nutraceutical. This review focuses on the mechanistic action of maslinic acid in regulating the inflammation pathways through modulation of the arachidonic acid metabolism including the nuclear factor-kappa B (NF-κB)/COX-2 expression, upstream protein kinase signaling, and phospholipase A₂ enzyme activity. Further investigations may provide insight into the mechanism of maslinic acid in regulating the molecular targets and their associated pathways in response to specific inflammatory stimuli.

Fat intake after prostate cancer diagnosis and mortality in the Physicians' Health Study

PURPOSE

Diet after prostate cancer diagnosis may impact disease progression. We hypothesized that consuming saturated fat after prostate cancer diagnosis would increase risk of mortality, and consuming vegetable fat after diagnosis would lower the risk of mortality.

METHODS

This was a prospective study among 926 men with non-metastatic prostate cancer in the Physicians' Health Study who completed a food frequency questionnaire a median of 5 years after diagnosis and were followed for a median of 10 years after the questionnaire. We examined post-diagnostic saturated, monounsaturated, polyunsaturated, and trans fat, as well as animal and vegetable fat, intake in relation to all-cause and prostate cancer-specific mortality. Hazard ratios (HR) and 95 % confidence intervals (CI) were estimated using multivariate Cox proportional hazards regression.

RESULTS

We observed 333 deaths (56 prostate cancer deaths) during follow-up. Men who obtained 5 % more of their daily calories from saturated fat and 5 % less of their daily calories from carbohydrate after diagnosis had a 1.8-fold increased risk of all-cause mortality (HR 1.81; 95 % CI 1.20, 2.74; p value 0.005) and a 2.8-fold increased risk of prostate cancer-specific mortality (HR 2.78; 95 % CI 1.01, 7.64; p value 0.05). Men who obtained 10 % more of their daily calories from vegetable fats and 10 % less of their daily calories from carbohydrates had a 33 % lower risk of all-cause mortality (HR 0.67; 95 % CI 0.47, 0.96; p value 0.03).

CONCLUSIONS

Among men with non-metastatic prostate cancer, saturated fat intake may increase risk of death and vegetable fat intake may lower risk of death.

Oleanolic Acid, a Compound Present in Grapes and Olives, Protects against Genotoxicity in Human Mammary Epithelial Cells

Oleanolic acid (AO) and maslinic acid (MA) are constituents of the skins of different fruits, including olives and white or red grapes. Although both compounds are known to have beneficial properties against different types of cancers, thus far, there are no studies about their chemopreventive effects in human breast cancer. Thus, we sought to elucidate whether both compounds possess chemopreventive activity. Two cell lines of human breast cancer cells and one noncancerous human mammary epithelial cells were used to determine the effects of OA and MA. The results showed that OA inhibited the proliferation and increased the oxidative stress of highly invasive cells. Additionally, OA decreased oxidative stress and oxidative damage to the DNA in human mammary epithelial cells. These results suggest that OA could act as a chemopreventive agent in human breast cancer and could inhibit the proliferation of highly invasive breast cancer cells.

Maslinic acid potentiates the antitumor activities of gemcitabine in vitro and in vivo by inhibiting NF-κB-mediated survival signaling pathways in human gallbladder cancer cells

Gemcitabine (GEM) is one of the first-line drugs in the treatment of gallbladder cancer (GBC), although the therapeutic effect is not sustained due to resistance to the drug over time. Maslinic acid (MA) has been shown to inhibit transcription factor nuclear factor-κB (NF-κB), resulting in the suppression of survival signaling. The authors of the present study investigated whether MA enhanced the antitumor activity of GEM in GBC. Anti-proliferative effects of MA, GEM and MA+GEM were assessed using the MTT assay. Apoptosis was assessed using Annexin V and by western blot analysis of various mediators of apoptosis. Xenograft tumors of EH-GB2 GBC cells were established in athymic nude mice and were monitored following treatment with MA, GEM and MA+GEM. Immunohistochemistry of the tumors was used to examine various survival proteins. MA inhibited the in vitro proliferation of various GBC cell lines and potentiated the apoptosis and cell invasion inhibition induced by GEM. Western blot analysis showed that the combination of MA and GEM inhibited constitutive NF-κB activation and NF-κB-regulated gene products, including cyclin D1, Bcl-2, Bax, MMP-2 and MMP-9, to a greater extent. In vivo, the group that was treated with MA+GEM showed significant reductions in tumor volume and a decreased expression of NF-κB-regulated gene products. In conclusion, the results suggest that MA potentiates the antitumor effects of GEM in human GBC cell lines by suppressing the activation of NF-κB and its dowstream gene products, which are involved in survival signaling.

Investigation of cytochrome P450 inhibitory properties of maslinic acid, a bioactive compound from Olea europaea L., and its structure-activity relationship

Maslinic acid (MA), the main pentacyclic triterpene of Olea europaea L. fruit, possesses a variety of pharmacological actions, including hypoglycemic, antioxidant, cardioprotective and antitumoral activities. Despite its importance, little is known about its effects on the cytochrome P450 (CYP) activity in both humans and animals. Therefore, the aim of this study was to investigate the effects of MA on the CYP 1A2, 2C9/11, 2D1/6, 2E1 and 3A2/4 activities by human and rat liver microsomes and specific CYP isoforms. In humans, MA only weakly inhibited CYP3A4 activity in human liver microsomes and specific CYP3A4 isoform with IC50 value at 46.1 and 62.3µM, respectively. In rats, MA also exhibited weak inhibition on CYP2C11, CYP2E1 and CYP3A2 activities with IC50 values more than 100µM. Enzyme kinetic studies showed that the MA was not only a competitive inhibitor of CYP3A4 in humans, but also a competitive inhibitor of CYP2C11 and 3A2 in rats, with Ki of 18.4, 98.7 and 66.3µM, respectively. Moreover, the presence of hydroxyl group at C-2 position of triterpenic acid in MA compared with oleanolic acid could magnify its competitive inhibition on human CYP3A4 activity. The relatively high Ki values of MA would have a low potential to cause the possible toxicity and drug interactions involving CYP enzymes, thus suggesting a sufficient safety for its putative use as a nutraceutical taken together with drugs.

GATA2 as a potential metastasis-driving gene in prostate cancer

Effective treatment for metastatic prostate cancer is critically needed. The present study was aimed at identifying metastasis-driving genes as potential targets for therapy (oncotargets). A differential gene expression profile of metastatic LTL-313H and non-metastatic LTL-313B prostate cancer tissue xenografts, derived from one patient's specimen, was subjected to integrative analysis using the Ingenuity Upstream Regulator Analysis tool. Six candidate master regulatory genes were identified, including GATA2, a gene encoding a pioneer factor, a special transcription factor facilitating the recruitment of additional transcription factors. Elevated GATA2 expression in metastatic prostate cancer tissues correlated with poor patient prognosis. Furthermore, GATA2 gene silencing in human prostate cancer LNCaP cells led to a marked reduction in cell migration, tissue invasion, focal adhesion disassembly and to a dramatic change in cell transcriptomes, indicating that GATA2 plays a critical role in prostate cancer metastasis. As such, GATA2 could represent a prostate cancer metastasis-driving gene and a potential target for therapy of metastatic prostate cancer.

Maslinic acid induces mitochondrial apoptosis and suppresses HIF-1α expression in A549 lung cancer cells under normoxic and hypoxic conditions

The apoptotic effects of maslinic acid (MA) at 4, 8, 16, 32 and 64 μmol/L on human lung cancer A549 cells under normoxic and hypoxic conditions were examined. MA at 4–64 and 16–64 μmol/L lowered Bcl-2 expression under normoxic and hypoxic conditions, respectively (p < 0.05). This agent at 4–64 μmol/L decreased Na⁺-K⁺-ATPase activity and increased caspase-3 expression under normoxic conditions, but at 8–64 μmol/L it caused these changes under hypoxic conditions (p < 0.05). MA up-regulated caspase-8, cytochrome c and apoptosis-inducing factor expression under normoxic and hypoxic conditions at 8–64 μmol/L and 32–64 μmol/L, respectively (p < 0.05). MA down-regulated hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), survivin and inducible nitric oxide synthase (iNOS) expression under normoxic and hypoxic conditions at 8–64 and 16–64 μmol/L, respectively (p < 0.05). After cells were pre-treated with YC-1, an inhibitor of HIF-1α, MA failed to affect the protein expression of HIF-1α, VEGF, survivin and iNOS (p > 0.05). MA at 8-64 and 32-64 μmol/L reduced reactive oxygen species and nitric oxide levels under both conditions (p < 0.05). These findings suggest that maslinic acid, a pentacyclic triterpenic acid, exerted its cytotoxic activities toward A549 cells by mediating mitochondrial apoptosis and the HIF-1α pathway.

Population pharmacokinetics of maslinic acid, a triterpene from olives, after intravenous and oral administration in rats

SCOPE

Maslinic acid is a bioactive minor component of Olea europaea L. with health-enhancing activities and no harmful effects. A pharmacokinetic (PK) study was conducted to determine its bioavailability for future studies of maslinic acid in humans.

METHODS AND RESULTS

Intravenous (1 mg/kg) and oral (50 mg/kg) administrations to Sprague-Dawley rats were performed. Blood was obtained several times over 24 h and PKs were analyzed with NONMEM 7.2, applying a population approach. Body weight was included a priori in the model with fixed allometric exponents, based on allometric principles. Plasma concentrations versus time were best characterized by a two-open compartment model with first-order absorption and linear elimination. Maslinic acid had a relative rapid oral absorption with a peak concentration after administration at 0.51 h and a bioavailability of 5.13%. Once in bloodstream, it distributed extensively into tissues, since the central and peripheral distribution volumes were 8.41 L/70 kg and 63.6 L/70 kg, respectively. The clearance (8 L/h/70 kg) was related to unaltered renal excretion. The prediction-corrected visual predictive check confirmed its stability and predictive ability.

CONCLUSION

An allometric population PK model was performed for maslinic acid, which adequately described and predicted plasma concentrations.

Maslinic acid, a natural phytoalexin-type triterpene from olives--a promising nutraceutical?

Maslinic acid is a pentacyclic triterpene found in a variety of natural sources, ranging from herbal remedies used in traditional Asian medicine to edible vegetables and fruits present in the Mediterranean diet. In recent years, several studies have proved that maslinic acid exerts a wide range of biological activities, i.e. antitumor, antidiabetic, antioxidant, cardioprotective, neuroprotective, antiparasitic and growth-stimulating. Experimental models used for the assessment of maslinic acid effects include established cell lines, which have been often used to elucidate the underlying mechanisms of action, and also animal models of different disorders, which have confirmed the effects of the triterpene in vivo. Overall, and supported by the lack of adverse effects in mice, the results provide evidence of the potential of maslinic acid as a nutraceutical, not only for health promotion, but also as a therapeutic adjuvant in the treatment of several disorders.

Carnosic acid inhibits the epithelial-mesenchymal transition in B16F10 melanoma cells: a possible mechanism for the inhibition of cell migration

Carnosic acid is a natural benzenediol abietane diterpene found in rosemary and exhibits anti-inflammatory, antioxidant, and anti-carcinogenic activities. In this study, we evaluated the effects of carnosic acid on the metastatic characteristics of B16F10 melanoma cells. When B16F10 cells were cultured in an in vitro Transwell system, carnosic acid inhibited cell migration in a dose-dependent manner. Carnosic acid suppressed the adhesion of B16F10 cells, as well as the secretion of matrix metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1, urokinase plasminogen activator (uPA), and vascular cell adhesion molecule (VCAM)-1. Interestingly, secretion of TIMP-2 increased significantly in B16F10 cells treated with 10 μmol/L carnosic acid. Additionally, carnosic acid suppressed the mesenchymal markers snail, slug, vimentin, and N-cadherin and induced epithelial marker E-cadherin. Furthermore, carnosic acid suppressed phosphorylation of Src, FAK, and AKT. These results indicate that inhibition of the epithelial-mesenchymal transition may be important for the carnosic acid-induced inhibition of B16F10 cell migration.

Membrane composition and dynamics: a target of bioactive virgin olive oil constituents

The endogenous synthesis of lipids, which requires suitable dietary raw materials, is critical for the formation of membrane bilayers. In eukaryotic cells, phospholipids are the predominant membrane lipids and consist of hydrophobic acyl chains attached to a hydrophilic head group. The relative balance between saturated, monounsaturated, and polyunsaturated acyl chains is required for the organization and normal function of membranes. Virgin olive oil is the richest natural dietary source of the monounsaturated lipid oleic acid and is one of the key components of the healthy Mediterranean diet. Virgin olive oil also contains a unique constellation of many other lipophilic and amphipathic constituents whose health benefits are still being discovered. The focus of this review is the latest evidence regarding the impact of oleic acid and the minor constituents of virgin olive oil on the arrangement and behavior of lipid bilayers. We highlight the relevance of these interactions to the potential use of virgin olive oil in preserving the functional properties of membranes to maintain health and in modulating membrane functions that can be altered in several pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Bioactive properties of the main triterpenes found in olives, virgin olive oil, and leaves of Olea europaea

Oleanolic acid, maslinic acid, uvaol, and erythrodiol are the main triterpenes present in olives, olive tree leaves, and virgin olive oil. Their concentration in virgin olive oil depends on the quality of the olive oil and the variety of the olive tree. These triterpenes are described to present different properties, such as antitumoral activity, cardioprotective activity, anti-inflammatory activity, and antioxidant protection. Olive oil triterpenes are a natural source of antioxidants that could be useful compounds for the prevention of multiple diseases related to cell oxidative damage. However, special attention has to be paid to the concentrations used, because higher concentration may lead to cytotoxic or biphasic effects. This work explores all of the bioactive properties so far described for the main triterpenes present in virgin olive oil.

SRPK1 Dissimilarly Impacts on the Growth, Metastasis, Chemosensitivity and Angiogenesis of Glioma in Normoxic and Hypoxic Conditions

Glioma is among the ten most common causes of cancer-related death and has no effective treatment for it, so we are trying to find a new target for anticancer treatment. This study investigates the different expression of SRPK1 as a novel protein in glioma, which can influence tumor cells biological characteristics in normoxic and hypoxic environment. The expression levels of SRPK1 protein in glioma cell lines transfected with siSRPK1 or not were examined using immunofluorescence, RT-PCR and Western blot analysis, respectively. The impact of SRPK1 on the biological characteristics of U251 cells was further studied using methylthiazol tetrazolium assays, flow cytometry, and Transwell invasion chamber assays. The results showed that knockdown of SRPK1 inhibited tumor cells growth, invasion and migration in normoxic condition, but portion of the effect could be reversed in hypoxia. SRPK1 expression was induced in glioma cells by DDP treated, but not TMZ, in both normoxia and hypoxia conditions. We propose SRPK1 as a new molecular player contributing to the early treatment of glioma.