Investigation of extrinsic and intrinsic apoptosis pathways of new clerodane diterpenoids in human prostate cancer PC-3 cells

Unreported ent-rosane diterpenes from Croton niveus Jacq. (Euphorbiaceae). Cytotoxic activity and docking studies

From the bioactive extract of the euphorbiaceous Croton niveus Jacq., three previously unreported ent-rosane diterpenes have been isolated and characterized by conventional methods, in addition to the known compounds lupeol, cajucarinolide and some phytosterols. Two of the ent-rosane diterpenes displayed activity against HCT-15 and PC-3 cancer cell lines, and the results of docking calculations of these compounds with NF-κB and STAT3 receptors agreed with the proposed mode of action of diterpenes against PC-3 cells.

Clerodane Diterpenoids from an Edible Plant Justicia insularis: Discovery, Cytotoxicity, and Apoptosis Induction in Human Ovarian Cancer Cells

OBJECTIVES

The toxicity of chemotherapeutic anticancer drugs is a serious issue in clinics. Drug discovery from edible and medicinal plants represents a promising approach towards finding safer anticancer therapeutics. Justicia insularis T. Anderson (Acanthaceae) is an edible and medicinal plant in Nigeria. This study aims to discover cytotoxic compounds from this rarely explored J. insularis and investigate their underlying mechanism of action.

METHODS

The cytotoxicity of the plant extract was evaluated in human ovarian cancer cell lines and normal human ovarian surface epithelia (HOE) cells using a sulforhodamine B assay. Bioassay-guided isolation was carried out using column chromatography including HPLC, and the isolated natural products were characterized using GC-MS, LC-HRMS, and 1D/2D NMR techniques. Induction of apoptosis was evaluated using Caspase 3/7, 8, and 9, and Annexin V and PI based flow cytometry assays. SwissADME and SwissTargetPrediction web tools were used to predict the molecular properties and possible protein targets of identified active compounds. Key finding: The two cytotoxic compounds were identified as clerodane diterpenoids: 16(α/β)-hydroxy-cleroda-3,13(14)Z-dien-15,16-olide (1) and 16-oxo-cleroda-3,13(14)E-dien-15-oic acid (2) from the Acanthaceous plant for the first time. Compound 1 was a very abundant compound (0.7% per dry weight of plant material) and was shown to be more potent than compound 2 with IC₅₀ values in the micromolar range against OVCAR-4 and OVCAR-8 cancer cells. Compounds 1 and 2 were less cytotoxic to HOE cell line. Both compounds induced apoptosis by increasing caspase 3/7 activities in a concentration dependent manner. Compound 1 further increased caspase 8 and 9 activities and apoptosis cell populations. Compounds 1 and 2 are both drug like, and compound 1 may target various proteins including a kinase.

CONCLUSIONS

Clerodane diterpenoids (1 and 2) in J. insularis were identified as cytotoxic to ovarian cancer cells via the induction of apoptosis, providing an abundant and valuable source of hit compounds for the treatment of ovarian cancer.

Molecular Basis of Prostate Cancer and Natural Products as Potential Chemotherapeutic and Chemopreventive Agents

Prostate cancer is the second most common malignant cancer in males. It involves a complex process driven by diverse molecular pathways that closely related to the survival, apoptosis, metabolic and metastatic characteristics of aggressive cancer. Prostate cancer can be categorized into androgen dependent prostate cancer and castration-resistant prostate cancer and cure remains elusive due to the developed resistance of the disease. Natural compounds represent an extraordinary resource of structural scaffolds with high diversity that can offer promising chemical agents for making prostate cancer less devastating and curable. Herein, those natural compounds of different origins and structures with potential cytotoxicity and/or in vivo anti-tumor activities against prostate cancer are critically reviewed and summarized according to the cellular signaling pathways they interfere. Moreover, the anti-prostate cancer efficacy of many nutrients, medicinal plant extracts and Chinese medical formulations were presented, and the future prospects for the application of these compounds and extracts were discussed. Although the failure of conventional chemotherapy as well as involved serious side effects makes natural products ideal candidates for the treatment of prostate cancer, more investigations of preclinical and even clinical studies are necessary to make use of these medical substances reasonably. Therefore, the elucidation of structure-activity relationship and precise mechanism of action, identification of novel potential molecular targets, and optimization of drug combination are essential in natural medicine research and development.

Dolabellane and Clerodane Diterpenoids from the Twigs and Leaves of Casearia kurzii

A pair of enantiomeric 15-nordolabellane diterpenoids, (-)- and (+)-caseadolabellols A (1a and 1b), three dolabellane diterpenoids, caseadolabellols B-D (2-4), two dolastane diterpenoids, caseadolastols A and B (5 and 6), 10 clerodane diterpenoids, caseakurzins A-J (7-16), and nine known diterpenoids (17-25) were isolated from the twigs and leaves of Casearia kurzii. The structures of the new compounds were established on the basis of extensive spectroscopic data, and those of compounds 1a, 1b, and 2 were verified by single-crystal X-ray crystallographic analysis. The enantiomers 1a and 1b were separated by chiral-phase HPLC. The absolute configurations were determined by experimental and calculated ECD data, the modified Mosher's method, or literature comparison. Compounds 1a and 5 showed significant quinone reductase-inducing activity in Hepa 1c1c7 cells, while 1b showed moderate activity. Molecular docking studies showed that 1a had greater binding affinity with Nrf2 protein (5FNQ) than 1b. The cytotoxic activity of compounds 1a, 1b, 2-12, 15, and 16 was evaluated, among which compounds 8 and 16 exhibited significant inhibitory activity against the A549 cell line. Compounds 8 and 16 induced the A549 cells to arrest at G2/M and S phases, respectively, and both compounds induced apoptosis in A549 cells.

Clerodane Diterpenoids Isolated from the Leaves of Casearia graveolens

A phytochemical survey aiming to acquire pharmacologically active substances has resulted in the isolation of nine new clerodane diterpenoids, named graveospenes A-I (1-9), from the leaves of Casearia graveolens. Spectroscopic methods were employed to establish the structures with their absolute configurations being confirmed by ECD data analysis. A biological evaluation was performed, and compound 1 was found to be cytotoxic to both human lung cancer cells (A549) and human hepatocellular carcinoma cells (HepG2). A mechanism-of-action study on 1 revealed this compound to induce apoptosis of A549 cells and impede them at the G₀/G₁ stage.

Antileishmanial Activity and Immunomodulatory Effects of Tricin Isolated from Leaves of Casearia arborea (Salicaceae)

Bioactivity-guided fractionation of antileishmanial active extract from leaves of Casearia arborea led to isolation of three metabolites: tricin (1), 1',6'-di-O-β-d-vanilloyl glucopyranoside (2) and vanillic acid (3). Compound 1 demonstrated the highest activity against the intracellular amastigotes of Leishmania infantum, with an IC₅₀ value of 56 μm. Tricin (1) demonstrated selectivity in mammalian cells (SI > 7) and elicited immunomodulatory effect on host cells. The present work suggests that tricin modulated the respiratory burst of macrophages to a leishmanicidal state, contributing to the parasite elimination. Therefore, the natural compound tricin could be further explored in drug design studies for leishmaniasis treatment.

Targeting Apoptosis with Dietary Bioactive Agents

Apoptosis, a form of programmed cell death, is a pivotal defense against the occurrence of cancer and is essential to metazoans in maintaining tissue homeostasis. Apoptosis exhibits a distinctive phenotype and involves elimination of potentially deleterious cells. Many diseases have been associated with aberrantly regulated apoptotic cell death, ultimately leading to inhibition of apoptosis and propagation of diseases such as cancer. Elucidation of the critical events associated with carcinogenesis provides the opportunity for dietary intervention to prevent cancer development through induction of apoptosis, Particularly by bioactive agents or functional foods. Diet is a significant environmental factor in the overall cancer process and can exacerbate or interfere with carcinogenesis. Apoptosis occurs primarily through two well-recognized pathways in cells, including the Intrinsic, or mitochondrial-mediated, effector mechanism and the extrinsic, or death receptor-mediated, effector mechanism. In addition to diet's effects on protein expression and function, evidence is also accumulating that a large number of dietary food components can exert effects on the human genome, either directly or indirectly, to modulate gene expression. In fact, many diet-related genes are involved in carcinogenesis as well as apoptosis, and thus are ultimately molecular targets for dietary chemopreventlon. There are multiple steps within pathways in which dietary components can alter gene expression and phenotypes of cells and thus influence cancer outcomes (nutritional transcriptomic effect). Thus, apoptosis is an emerging therapeutic target of bioactive agents of diet. In this review, the process of apoptosis is discussed and the potential mechanistic interaction of bioactive agents, as components of functional foods, is explored within the context of apoptosis.

Preclinical anticancer effectiveness of a fraction from Casearia sylvestris and its component Casearin X: in vivo and ex vivo methods and microscopy examinations

ETHNOPHARMACOLOGICAL RELEVANCE

Casearia sylvestris (Salicaceae) is found in South America and presents antiulcerogenic, cytotoxic, antimicrobial, anti-inflammatory and antihypertensive activities.

AIM OF THE STUDY

To assess the in vivo and ex vivo antitumor action of a fraction with casearins (FC) and its main component - Casearin X-isolated from C. sylvestris leaves.

MATERIALS AND METHODS

Firstly, Sarcoma 180 bearing Swiss mice were treated with FC and Cas X for 7 days. Secondly, BALB/c nude animals received hollow fibers with colon carcinoma (HCT-116) or glioblastoma (SF-295) cells and were treated with FC for 4 days. On 5th day, proliferation was determined by MTT assay.

RESULTS

FC 10 and 25mg/kg/day i.p. and 50mg/kg/day oral and Cas X 25mg/kg/day i.p. and 50mg/kg/day oral revealed tumor growth inhibition rates of 35.8, 86.2, 53.7, 90.0 and 65.5% and such tumors demonstrated rare mitoses and coagulation necrosis areas. Similarly, FC reduced multiplying of HCT-116 and SF-295 cells when evaluated by the Hollow Fiber Assay (2.5 and 5mg/kg/day i.p. and 25 and 50mg/kg/day oral), with cell growth inhibition rates ranging from 33.3 to 67.4% (p<0.05). Flow cytometry experiments revealed that FC reduced membrane integrity and induced DNA fragmentation and mitochondrial depolarization (p<0.05).

CONCLUSIONS

FC and Cas X were efficient antitumor substances against murine and human cancer cells and caused reversible morphological changes in liver, kidneys and spleens, emphasizing clerodane diterpenes as an emerging class of anticancer molecules.

How Phytochemicals Prevent Chemical Carcinogens and/or Suppress Tumor Growth?

Phytochemicals are a powerful group of chemicals that are derived from natural resource, especially with plants origin. They have shown to exhibit chemoprevention and chemotherapeutic effects not only in cell lines and in animal models of cancer but also some of them are in the clinical trial phase I and II. Despite numerous reports of these phytochemical effects on cancer, an overview of the mechanisms of their action and their effects on various cellular and molecular functions important in the inhibition of cancer progression has been lacking. In this review, we attempt to catalogue various studies to examine the effect of phytochemicals in cancer initiation, promotion, signaling, and epigenetic changes. Because of the numerous studies in these topics, we only pointed out to some examples in each section.

Discovery of Tricyclic Clerodane Diterpenes as Sarco/Endoplasmic Reticulum Ca(2+)-ATPase Inhibitors and Structure-Activity Relationships

Tricyclic clerodane diterpenes (TCDs) are natural compounds that often show potent cytotoxicity for cancer cells, but their mode of action remains elusive. A computationally based similarity search (CDRUG), combined with principal component analysis (ChemGPS-NP) and docking calculations (GOLD 5.2), suggested TCDs to be inhibitors of the sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) pump, which is also the target of the sesquiterpene lactone thapsigargin. Biochemical studies were performed with 11 TCDs on purified rabbit skeletal muscle sarcoplasmic reticulum membranes, which are highly enriched with the SERCA1a isoform. Casearborin D (2) exhibited the highest affinity, with a KD value of 2 μM and giving rise to complete inhibition of SERCA1a activity. Structure-activity relationships revealed that functionalization of two acyl side chains (R1 and R4) and the hydrophobicity imparted by the aliphatic chain at C-9, as well as a C-3,C-4 double bond, play crucial roles for inhibitory activity. Docking studies also suggested that hydrophobic interactions in the binding site, especially with Phe256 and Phe834, may be important for a strong inhibitory activity of the TCDs. In conclusion, a novel class of SERCA inhibitory compounds is presented.

Upregulation of death receptor 5 and activation of caspase 8/3 play a critical role in ergosterol peroxide induced apoptosis in DU 145 prostate cancer cells

Background

Though ergosterol peroxide (EP) derived from Neungyi mushrooms (Sarcodon aspratus) was known to have cytotoxic, apoptotic, anti-inflammatory and antimycobacterial effects, the underlying molecular mechanism of EP still remains unclear. Thus, in the present study, the apoptotic mechanism of EP was elucidated in DU 145 prostate cancer cells.

Methods

Cell viability of prostate cancer cells was measured by MTT assay. To see whether EP induces the apoptosis, FACS, western blot and TUNEL assay were performed. To determine the role of Death receptor (DR) 5 molecules in EP-induced apoptosis in DU 145 prostate cancer cells, the silencing of DR 5 was performed by using siRNAs.

Results

EP showed significant cytotoxicity against DU 145, PC 3, M2182 prostate cancer cells. Also, EP effectively increased the sub G1 population and terminal deoxynucleotidyl transferase DUTP nick end labeling (TUNEL) positive cells in DU 145 prostate cancer cells. Furthermore, western blotting revealed that EP cleaved poly (ADP-ribose) polymerase (PARP) and caspase 8/3, attenuated the expression of fluorescence loss in photobleaching (FLIP), Bcl-_XL and Bcl-2 as well as activated Bax, Fas-associated death domain (FADD) and DR 5 in a concentration dependent manner in DU 145 prostate cancer cells. Conversely, caspase 8 inhibitor Z-IETD-FMK blocked the apoptotic ability of EP to cleave PARP and an increase of sub G1 population in DU 145 prostate cancer cells. Likewise, the silencing of DR 5 suppressed the cleavages of PARP induced by EP in DU 145 prostate cancer cells.

Conclusion

Overall, our findings suggest that ergosterol peroxide induces apoptosis via activation of death receptor 5 and caspase 8/3 in DU 145 prostate cancer cells as a cancer chemopreventive agent or dietary factor.

Investigation of the effect of telmisartan on experimentally induced peripheral nerve injury in rats

AIM

The aim of this study was to investigate the effects of telmisartan on nerve healing in a rat peripheral nerve injury model.

MATERIAL AND METHOD

Thirty adult male Wistar albino rats were divided into five groups: healthy, axonotmesis, anastomosis, axonotmesis+10 mg/kg telmisartan and anastomosis+10 mg/kg telmisartan. Walking track analyses were performed 4 weeks after the surgery. The right sciatic nerves of all the animals were examined histopathologically, stereologically and molecularly.

RESULTS

Many badly damaged axons were detected in the axonotmesis group, in addition to enlarged spaces between the axons. In the anastomosis group, both ir- regular and degenerated axons at different severities were observed. The sections of the telmisartan group after the axonotmesis were similar to those of the healthy group. The sections of the telmisartan group after the anastomosis were similar to those of the healthy group and the telmisartan group after the axonotmesis. Interleukin-1 beta (IL-1β) gene expression increased in both the axonotmesis and the anastomosis groups when compared with the healthy group. Telmisartan had a significant down-regulatory effect on IL-1β expression. Caspase-3 mRNA expression was significantly increased in the anastomosis group, and the administration of telmisartan in this group significantly decreased this rise in caspase-3 mRNA expression. As a functional outcome, telmisartan also increased the walking distance of the rats after axonotmesis and anastomosis.

CONCLUSION

The histopathological, stereological, functional and molecular data suggest that telmisartan improves nerve regeneration in peripheral nerve injuries by inhibiting inflammatory cytokine IL-1β and apoptotic caspase-3.

Induction of apoptosis in cholangiocarcinoma by an andrographolide analogue is mediated through topoisomerase II alpha inhibition

Cholangiocarcinoma (CCA), the common primary malignant tumor of bile duct epithelial cells, is unresponsive to most chemotherapeutic drugs. Diagnosis with CCA has a poor prognosis, and therefore urgently requires effective therapeutic agents. In the present study we investigated anti-cancer effects of andrographolide analogue 3A.1 (19-tert-butyldiphenylsilyl-8, 17-epoxy andrographolide) and its mechanism in human CCA cell line KKU-M213 derived from a Thai CCA patient. By 24h after exposure, the analogue 3A.1 exhibited a potent cytotoxic effect on KKU-M213 cells with an inhibition concentration 50 (IC50) of approximately 8.0µM. Analogue 3A.1 suppressed DNA topoisomerase II α (Topo II α) protein expression, arrested the cell cycle at sub G0/G1 phase, induced cleavage of DNA repair protein poly (ADP-ribose) polymerases-1 (PARP-1), and enhanced expression of tumor suppressor protein p53 and pro-apoptotic protein Bax. In addition, analogue 3A.1 induced caspase 3 activity and inhibited cyclin D1, CDK6, and COX-2 protein expression. These results suggest that andrographolide analogue 3A.1, a novel topo II inhibitor, has significant potential to be developed as a new anticancer agent for the treatment of CCA.

Cytotoxic clerodane diterpenoids from the leaves and twigs of Casearia balansae

Ten new clerodane diterpenoids (1-10), caseabalansins A-G, 18-epicaseabalansin A, 2-epicaseabalansin B, and 2-epicaseabalansin C, one new triterpenoid, balansinone (11), and seven known diterpenoids (12-18) were obtained from the leaves and twigs of Casearia balansae. Compounds 1 and 2 are the first examples of clerodane diterpenoids with an oxygen bridge between C-2 and C-19, and compounds 5-7 are three new diterpenoid artifacts presumably formed during the extraction process. The structures of the new compounds were established on the basis of extensive spectroscopic data, and that of 11 was verified by single-crystal X-ray crystallographic analysis. Compound 15 showed cytotoxic activity against the tumor cell lines PC3, DU145, SKOV3, and A549 with IC₅₀ values of 4.5, 4.3, 5.1, and 5.7 μM, respectively. Compounds 1a, 2a, and 4 showed selective activity against PC3 tumor cells.

Simultaneous determination of arctiin and its metabolites in rat urine and feces by HPLC

Arctiin, an important lignan compound in Fructus Arctii, has been reported to possess various kinds of bioactivities. Previous studies on the pharmacokinetic of arctiin after oral administration showed that it had a rapid absorption phase followed by a sharp but lasting disappearance. To gain deep insight into the action mechanism of arctiin, the excretion and metabolism of arctiin in vivo should be further studied. In this paper, three metabolites were isolated and identified in rat feces as (-)-enterolactone (M-1), (-)-arctigenin (M-2) and [(2R,3R)-2-(3'-hydroxybenzyl)-3-(3″,4″-dimethoxybenzyl)-butyrolactone] (M-3). Based on the structures of three metabolites, possible metabolic pathways of arctiin in rats are proposed. At the same time, the cumulative excretion rate of arctiin and its metabolites in rat urine and feces were determined, indicating that arctiin was excreted 19.84% in urine and 1.80% in feces, respectively, enterolactone, the most main metabolite, was excreted 35.80% in feces. These results provide very important information for understanding the metabolism and excretion of arctiin in vivo and speculating its action mechanism, they can provide useful information and reference for further metabolic investigations on arctiin in humans.

α-Tomatine-mediated anti-cancer activity in vitro and in vivo through cell cycle- and caspase-independent pathways

α-Tomatine, a tomato glycoalkaloid, has been reported to possess antibiotic properties against human pathogens. However, the mechanism of its action against leukemia remains unclear. In this study, the therapeutic potential of α-tomatine against leukemic cells was evaluated in vitro and in vivo. Cell viability experiments showed that α-tomatine had significant cytotoxic effects on the human leukemia cancer cell lines HL60 and K562, and the cells were found to be in the Annexin V-positive/propidium iodide-negative phase of cell death. In addition, α-tomatine induced both HL60 and K562 cell apoptosis in a cell cycle- and caspase-independent manner. α-Tomatine exposure led to a loss of the mitochrondrial membrane potential, and this finding was consistent with that observed on activation of the Bak and Mcl-1 short form (Mcl-1s) proteins. Exposure to α-tomatine also triggered the release of the apoptosis-inducing factor (AIF) from the mitochondria into the nucleus and down-regulated survivin expression. Furthermore, α-tomatine significantly inhibited HL60 xenograft tumor growth without causing loss of body weight in severe combined immunodeficiency (SCID) mice. Immunohistochemical test showed that the reduced tumor growth in the α-tomatine-treated mice was a result of increased apoptosis, which was associated with increased translocation of AIF in the nucleus and decreased survivin expression ex vivo. These results suggest that α-tomatine may be a candidate for leukemia treatment.

Anti-inflammatory function of arctiin by inhibiting COX-2 expression via NF-κB pathways

BACKGROUND

Arctiin, isolated from Forsythia suspensa has been reported to have anti-inflammatory, anti-oxidant, antibacterial, and antiviral effects in vitro. However, there has been a lack of studies regarding its effects on immunological activity. The aim of this study is to investigate the anti-inflammatory potential and possible mechanisms of arctiin in LPS-induced macrophages.

METHODS

We investigated the mRNA and protein levels of proinflammatory cytokines through RT-PCR and western blot analysis, followed by a FACS analysis for surface molecule changes.

RESULTS

Arctiin dose dependently decreased the production of NO and proinflammatory cytokines such as IL-1β, IL-6, TNF-α, and PGE2, and it reduced the gene and protein levels as determined by RT-PCR and western blot analysis, respectively. The expression of co-stimulatory molecules such as B7-1 and B7-2 were also inhibited by arctiin. Furthermore, the activation of the nuclear transcription factor, NF-κB in macrophages was inhibited by arctiin.

CONCLUSION

Taken together these results provide evidence of the bioactivity of arctiin in inflammatory diseases and suggest that arctiin may exert anti-inflammatory effect by inhibiting the pro-inflammatory mediators through the inactivation of NF-kB.

Clerodane diterpenes from Casearia arguta that act as synergistic TRAIL sensitizers

Casearia arguta was investigated as part of the ongoing search for synergistic TRAIL (tumor necrosis factor-α-related apoptosis-inducing ligand) sensitizers. As a result of this study, argutins A-H, eight new highly oxygenated clerodane diterpenes, were isolated from the plant Casearia arguta collected in Guatemala. The modified Mosher ester method was utilized to establish the absolute configuration of argutins A and F. Each of the argutins showed varying levels of synergy with TRAIL. Argutin B showed the highest TRAIL sensitization; the synergistic effect of argutin B and TRAIL together was 3-fold greater than argutin B alone.

Casearin X exhibits cytotoxic effects in leukemia cells triggered by apoptosis

Clerodane diterpenes have demonstrated cytotoxic, antiplasmodial and anti-ulcer properties. In the present work, we determined the cytotoxic effect of casearin L (Cas L), O (Cas O) and X (Cas X) and (-)-hardwickiic acid isolated from Casearia sylvestris leaves, and investigated the underlying mechanisms involved in in vitro cell death induced by Cas X in HL-60 leukemia cells (0.7, 1.5 and 3.0μM). Cytotoxicity tests demonstrated that Cas X was the most active compound studied, showing greater cytotoxic effects against CEM and HL-60 lines (IC(50) of 0.4μM) and human peripheral blood mononuclear cells (PBMC, IC(50) of 1.2μM). After 24h exposure, Cas X caused a decrease in 5-bromo-20-deoxyuridine (BrdU) incorporation (36.6 and 24.5% labeling at 0.7 and 1.5μM, respectively), reduction in viability, and increase in apoptotic and necrotic leukemia cells in a dose-dependent manner evidenced by the trypan blue and AO/EB (acridine orange/ethidium bromide) assays. Moreover, Cas X-treated cells exhibited nuclear fragmentation and cytoplasmic vacuolization depending on the concentration tested. These characteristics of apoptosis or secondary necrosis were confirmed by flow cytometry which revealed DNA fragmentation, phosphatidylserine externalization, activation of the effector caspases 3/7 and mitochondrial depolarization. We then found evidence that Cas X causes cell death via apoptotic pathways, corroborating the potential of casearins as compounds with promising antitumor-related properties.

Modification of alternative splicing of Mcl-1 pre-mRNA using antisense morpholino oligonucleotides induces apoptosis in basal cell carcinoma cells

Myeloid cell leukemia-1 (Mcl-1, Mcl-1L) is an anti-apoptotic protein of the Bcl-2 family that acts as a critical molecule in apoptosis control. Mcl-1 pre-mRNA can undergo alternative splicing to yield the short isoform, Mcl-1S, which resembles BH3-only pro-apoptotic proteins and induces apoptosis. Overexpression of Mcl-1 may play a role in various human tumors, and Mcl-1 may serve as a target in cancer therapy. In this study, we found an imbalance between the expression levels of Mcl-1L and Mcl-1S in the skin basal cell carcinoma (BCC) cell line when compared with primary keratinocytes. We showed that overexpression of Mcl-1S induces apoptosis in BCC cells. Finally, we showed that Mcl-1 antisense morpholino oligonucleotides (AMOs) can specifically target Mcl-1 pre-mRNA and shift the splicing pattern from Mcl-1L to Mcl-1S mRNA and protein. This shift increases the level of pro-apoptotic Mcl-1S and reduces the level of anti-apoptotic Mcl-1L, which induces apoptosis in BCC cells and AGS cells, a human gastric adenocarcinoma epithelial cell line. Thus, this report provides a strategy for cancer therapy in which AMOs change the alternative splicing pattern of Mcl-1 pre-mRNA and thereby induce apoptosis.

Inhibitory effects of 16-hydroxycleroda-3,13(14)E-dien-15-oic acid on superoxide anion and elastase release in human neutrophils through multiple mechanisms

Reactive oxygen species and granule proteases produced by neutrophils contribute to the pathogenesis of inflammatory diseases. In this study, a cellular model in isolated human neutrophils was established to elucidate the anti-inflammatory functions of 16-hydroxycleroda-3,13(14)E-dien-15-oic acid (PL3S), a clerodane diterpenoid from Formosan Polyalthia longifolia var. pendula. PL3S significantly inhibited the generation of superoxide anion and the release of elastase in formyl-l-methionyl-l-leucyl-l-phenylalanine (FMLP)-activated human neutrophils in a concentration-dependent fashion with IC50 values of 3.06+/-0.20 and 3.30+/-0.48 microM, respectively. PL3S did not affect cAMP-dependent pathway, and the inhibitory effect of PL3S was not reversed by protein kinase A inhibitor. PL3S did not display antioxidant or superoxide anion-scavenging ability, and it failed to alter the subcellular NADPH oxidase activity. PL3S concentration-dependently inhibited calcium mobilization caused by FMLP but not thapsigargin. Furthermore, PL3S attenuated the FMLP-induced protein kinase B (AKT) and p38 mitogen-activated protein kinase phosphorylation. However, PL3S had no effect on FMLP-induced phosphorylation of extracellular regulated kinase and c-Jun N-terminal kinase. In summary, these results indicate that the suppressive effects of PL3S on human neutrophil respiratory burst and degranulation are at least partly mediated by inhibition of calcium, AKT, and p38 signaling pathways.

Blockade of AT1 Receptor Reduces Apoptosis, Inflammation, and Oxidative Stress in Normotensive Rats with Intracerebral Hemorrhage

Angiotensin II exerts its central nervous system effects primarily via its receptors AT1 and AT2, and it participates in the pathogenesis of ischemia via AT1. The selective AT1 receptor blocker (ARB) is used in the hypertension treatment, and it exerts a variety of pleiotropic effects, including antioxidative, antiapoptotic, and anti-inflammatory effects. In this study, we investigated the therapeutic effect of the ARB telmisartan in experimental intracerebral hemorrhage (ICH) in normotensive rats. ICH was induced via the collagenase infusion or autologous blood injection. Either telmisartan at 30 mg/kg/dose or phosphate-buffered saline was orally administered 2 h after ICH induction. We evaluated hemorrhage volume, brain water content, and functional recovery, and we performed the histological analysis for terminal deoxynucleotidyl transferase dUTP nick-end labeling, leukocyte infiltration, and microglia activation. A variety of intracellular signals, in terms of oxidative stress, apoptotic molecules, and inflammatory mediators, were also measured. Telmisartan reduced hemorrhage volume, brain edema, and inflammatory or apoptotic cells in the perihematomal area. Telmisartan was noted to induce the expression of endothelial nitric-oxide synthase and peroxisome proliferator-activated receptor gamma and decrease oxidative stress, apoptotic signal, tumor necrosis factor-alpha, and cyclooxygenase-2 expression. The telmisartan-treated rats exhibited less pronounced neurological deficits and recovered better. Thus, telmisartan seems to offer neural protection, including antiapoptosis, anti-inflammatory, and antioxidant benefits in the intracerebral hemorrhage rat model.

Erythropoietin reduces perihematomal inflammation and cell death with eNOS and STAT3 activations in experimental intracerebral hemorrhage

Erythropoietin (EPO), a pleiotropic cytokine involved in erythropoiesis, is tissue-protective in ischemic, traumatic, toxic and inflammatory injuries. In this study, we investigated the effect of EPO in experimental intracerebral hemorrhage (ICH). Two hours after inducing ICH via the stereotaxic infusion of collagenase, recombinant human EPO (500 or 5000 IU/kg, ICH + EPO group) or PBS (ICH + vehicle group) was administered intraperitoneally, then once daily afterwards for 1 or 3 days. ICH + EPO showed the better functional recovery in both rotarod and modified limb placing tests. The brain water content was decreased in ICH + EPO dose-dependently, as compared with ICH + vehicle. The effect of EPO on the brain water content was inhibited by N(omega)-Nitro-L-arginine methyl ester hydrochloride (L-NAME, 10 mg/kg). Mean hemorrhage volume was also decreased in ICH + EPO. EPO reduced the numbers of TUNEL +, myeloperoxidase + or OX-42 + cells in the perihematomal area. In addition, EPO reduced the mRNA level of TNF-alpha, Fas and Fas-L, as well as the activities of caspase-8, 9 and 3. EPO treatment showed up-regulations of endothelial nitric oxide synthase (eNOS) and p-eNOS, pAkt, pSTAT3 and pERK levels. These data suggests that EPO treatment in ICH induces better functional recovery with reducing perihematomal inflammation and apoptosis, coupled with activations of eNOS, STAT3 and ERK.

Induction of endoplasmic reticulum stress and apoptosis by a marine prostanoid in human hepatocellular carcinoma

BACKGROUND/AIMS

Hepatocellular carcinoma is a very common malignancy and is highly chemoresistant to currently available chemotherapeutic agents. We isolated a marine prostanoid, bromovulone III, from soft coral Clavularia viridis and found that it displayed effective anti-tumor activity in human hepatocellular carcinoma. The anti-tumor mechanism has been delineated in this study.

METHODS

Anti-tumor efficacy and apoptotic cell death were examined by sulforhodamine B and Hoechst 33342 assays. Rhodamine 123 was used to measure the change of mitochondrial membrane potential. Immunoprecipitation and Western blotting detect the involvement of several apoptosis-related proteins. Electron microscopic examination detects the morphological change of mitochondria and endoplasmic reticulum (ER).

RESULTS

Bromovulone III primarily induced mitochondria-related activation of caspase-9 and -3 in several tumor types, such as prostate cancer PC-3 and acute promyelocytic leukemia HL-60 cells. However, it primarily induced the activation of m-calpain, caspase-12, and transcription factor CHOP/GADD153 in hepatocellular carcinoma Hep3B cells, suggesting the involvement of ER stress. Furthermore, a secondary mitochondrial swelling and depolarization of mitochondrial membrane potential were subsequently triggered after ER stress, suggesting the crosstalk between ER and mitochondria.

CONCLUSIONS

It is suggested that bromovulone III induces apoptosis in Hep3B cells through a mechanism that induces ER stress and leads to activation of CHOP/GADD153 and caspase-12.

SDX-101, the R-enantiomer of etodolac, induces cytotoxicity, overcomes drug resistance, and enhances the activity of dexamethasone in multiple myeloma

In this study we report that R-etodolac (SDX-101), at clinically relevant concentrations, induces potent cytotoxicity in drug-sensitive multiple myeloma (MM) cell lines, as well as in dexamethasone (MM.1R)-, doxorubicin (Dox40/RPMI8226)-, and bortezomib (DHL4)-resistant cell lines. Immunoblot analysis demonstrates that R-etodolac induces apoptosis characterized by caspase-8, -9, and -3 and PARP (poly-ADP [adenosine diphosphate]-ribose polymerase) cleavage and down-regulation of cyclin D1 expression. Subcytotoxic doses of R-etodolac up-regulate myeloid cell leukemia-1 proapoptotic variant (Mcl-1S), while enhancing dexamethasone (Dex)-induced caspase activation and apoptosis. The combination of R-etodolac with Dex results in a highly synergistic cytotoxic effect. R-etodolac also induces apoptosis against primary cells isolated from patients with MM refractory to chemotherapy. Although interleukin 6 (IL-6) and insulin-like growth factor-1 (IGF-1) abrogate Dex-induced MM cell cytotoxicity, neither IL-6 nor IGF-1 protects against R-etodolac-induced cytotoxicity in MM cells. R-etodolac also inhibits viability of MM cells adherent to bone marrow stromal cells (BMSCs), thereby overcoming a mechanism of drug resistance commonly observed with other conventional chemotherapeutic agents. Our data, therefore, indicate that R-etodolac circumvents drug resistance in MM cells at clinically relevant concentrations, targets Mcl-1, and can be synergistically combined with Dex.