Dysregulation of different modes of programmed cell death by epigenetic modifications and their role in cancer.

Modifications of epigenetic factors affect our lives and can give important information regarding one's state of health. In cancer, epigenetic modifications play a crucial role, as they influence various programmed cell death types. The purpose of this review is to investigate how epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNAs, influence various cell death processes in suppressing or promoting cancer development. Autophagy and apoptosis are the most investigated programmed cell death modes, as based on the tumor stage these cell death types can either promote or prevent cancer evolution. Therefore, our discussion focuses on how epigenetic modifications affect autophagy and apoptosis, as well as their diagnostic and therapeutical potential in combination with available chemotherapeutics. Additionally, we summarize the available data regarding the role of epigenetic modifications on other programmed cell death modes, such as ferroptosis, necroptosis, and parthanatos in cancer and discuss current advancements.

Ziziphora tenuior L. essential oil from Dana Biosphere Reserve (Southern Jordan); Chemical characterization and assessment of biological activities.

ETHNOPHARMACOLOGIC RELEVANCE: Ziziphora tenuior L. (Lamiaceae) is a medicinal plant in Jordan, which is included in various antimicrobial, antiseptic, expectorant and wound healing preparations. It is used for the treatment of cough, stomach ache, dysentery, fever, uterus infection, gut inflammation and painful menstruation. AIM OF THE STUDY: The aim of this study was to assess, for the first time, the chemical composition of the essential oil of Z. tenuior originated from southern Jordan and its antifungal effects against several yeasts. Concomitantly, the mechanisms behind the anti-fungal activity against Candida albicans were also disclosed. Since the Z. tenuior traditional uses are related with inflammatory-associated conditions, the putative anti-inflammatory activity of the oil was also unveiled. Importantly, the potential toxicity of pharmacologically active concentrations was screened in different types of mammalian cells. MATERIALS AND METHODS: Z. tenuior essential oil, isolated by hydrodistillation, was analyzed by gas chromatography, gas chromatography-mass spectrometry and 13C nuclear magnetic resonance spectroscopy. Antifungal activity was evaluated against yeasts, dermatophytes and Aspergillus strains. Germ tube inhibition and biofilm formation assays were evaluated using C. albicans. Assessment of cell viability was made by the MTT assay using different types of mammalian cells, including hepatocytes, keratinocytes and macrophages. The in vitro anti-inflammatory potential of the oil was evaluated by measuring nitric oxide production using lipopolysaccharide-stimulated mouse macrophages. RESULTS: Oxygen-containing monoterpenes are the main oil compounds: pulegone (46.8%), p-menth-3-en-8-ol (12.5%), isomenthone (6.6%) and 8-hydroxymenthone (6.2%). The highest antifungal activity was against Cryptococcus neoformans, with a MIC value of 0.16µL/mL. The oil revealed an important inhibitory effect on germ tube formation with a filamentation inhibition rate higher than 80% at 0.16µL/mL. The amount of the attached biomass was reduced. Importantly, concentrations devoid of toxicity on several mammalian cell types still displayed anti-inflammatory activity (0.16 and 0.32µL/mL). CONCLUSIONS: These findings add significant information to the pharmacological activity of Z. tenuior, thus justifying and reinforcing the use of this plant in traditional medicine. Additionally, the antifungal and anti-inflammatory potential of the oil at non-toxic concentrations, opens new avenues for its further exploitation, for instance in health-care product development.

Chemical composition and biological activities of Artemisia judaica essential oil from southern desert of Jordan.

ETHNOPHARMACOLOGIC RELEVANCE: Artemisia judaica L. (Arabic name: Beithran), is a medicinal and aromatic plant growing in the valley bottoms of desert areas, particularly in the southern desert of Jordan nearest to the Jordan-Saudi Arabia borders and in Wadi Araba in the Southern Badia. In Jordan, A. judaica is widely used in traditional medicine being recommended by aboriginal Bedouins in the North Badia region of Jordan as calmative. Furthermore, it is used for the treatment of stomach ache, heart diseases, sexual weakness, diabetes, gastro-intestinal disorders and external wounding. Additionally, other folk medicines of the Arabic region commonly use this aromatic plant for the treatment of inflammatory-related diseases, for instance fungal infections, diabetes, atherosclerosis, cancer and arthritis. AIM OF THE STUDY: Considering the traditional medicinal uses and the lack of scientific studies addressing the cellular and molecular mechanisms behind A. judaica claimed activities, the present study was designed to validate some of the traditional uses ascribed to this species, specifically the antifungal and anti-inflammatory activities of A. judaica essential oil at doses devoid of cytotoxicity to mammalian cells. MATERIALS AND METHODS: Chemical analysis of A. judaica essential oil isolated by hydrodistillation from aerial parts was carried out by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The antifungal activity (minimal inhibitory concentrations and minimal lethal concentrations) was evaluated against yeasts, dermatophyte and Aspergillus strains. In order to deeply explore the mechanisms behind the anti-fungal effect of the essential oil, the germ tube inhibition assay and the biofilms formation assay were evaluated using Candida albicans. The assessment of cell viability was accomplished using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in both hepatocytes and macrophages. Furthermore, the in vitro anti-inflammatory potential of A. judaica oil was evaluated by measuring nitric oxide (NO) production using lipopolysaccharide (LPS)-stimulated mouse macrophages. RESULTS: Oxygen containing monoterpenes are a representative group of constituents (68.7%) with piperitone (30.4%), camphor (16.1%) and ethyl cinnamate (11.0%) as main compounds. The highest antifungal activity of the oil was observed against Cryptococcus neoformans, with a MIC value of 0.16µL/mL. The oil revealed an important inhibitory effect on germ tube formation in C. albicans with 80% inhibition of filamentation at a concentration of 0.16µL/mL. Importantly, the oil also interfered with pre-formed biofilms by reducing the amount of the attached biomass. Furthermore, the essential oil significantly inhibited NO production evoked by LPS on macrophages at concentrations with very low toxicity (0.32µL/mL) or without toxicity (0.16µL/mL) to both macrophages and hepatocytes. CONCLUSIONS: The present study revealed that A. judaica essential oil from Jordan significantly inhibited germ tube formation and disrupted preformed biofilms of C. albicans, emphasizing the therapeutic potential for the treatment of disseminated candidiasis. Additionally, safe concentrations of this essential oil significantly inhibited NO production elicited by LPS in macrophages, highlighting its potential anti-inflammatory activity. Overall, A. judaica bears promising therapeutic potential for further drug development. Importantly, this work also validates some of the traditional uses of A. judaica.

Artemisia herba-alba essential oil from Buseirah (South Jordan): Chemical characterization and assessment of safe antifungal and anti-inflammatory doses.

ETHNOPHARMACOLOGIC RELEVANCE: Artemisia herba-alba Asso ("desert wormwood" in English; "armoise blanche" in French; "shaih" in Arabic), is a medicinal and strongly aromatic plant widely used in traditional medicine by many cultures since ancient times. It is used to treat inflammatory disorders (colds, coughing, bronchitis, diarrhea), infectious diseases (skin diseases, scabies, syphilis) and others (diabetes, neuralgias). In Jordanian traditional medicine, this plant is used as antiseptic and against skin diseases, scabies, syphilis, fever as well as menstrual and nervous disorders. AIM OF THE STUDY: Considering the traditional medicinal uses and the lack of scientific studies addressing the cellular and molecular players involved in these biological activities, the present study was designed to unveil the antifungal and anti-inflammatory activities of A. herba-alba Asso essential oil at doses devoid of toxicity to mammalian cells. MATERIALS AND METHODS: Chemical analysis of A. herba-alba essential oil isolated by hydrodistillation from aerial parts was carried out by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The antifungal activity (minimal inhibitory concentrations and minimal lethal concentrations) was evaluated against yeasts, dermatophyte and Aspergillus strains. In order to explore the mechanisms behind the anti-fungal effect of the essential oil, the germ tube inhibition assay was evaluated using Candida albicans. The assessment of cell viability was accomplished using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the in vitro anti-inflammatory potential of A. herba-alba oil at the periphery and central nervous system was evaluated by measuring nitric oxide (NO) production using lipopolysaccharide (LPS)-stimulated mouse macrophages and microglia, respectively. RESULTS: Oxygen-containing monoterpenes are the main compounds of the oil, namely 1,8-cineole (20.1%), ß-thujone (25.1%), α-thujone (22.9%) and camphor (10.5%). Among the fungal strains tested, the oil demonstrated potential against Trichophyton rubrum and Epidermophyton floccosum, with minimal inhibitory concentration (MIC) and minimal lethal concentration (MCL) values of 0.32 mg/mL and Cryptococcus neoformans with MIC of 0.64 mg/mL. The oil revealed a strong inhibitory effect on germ tube formation in C. albicans with inhibition of filamentation around 90% at a concentration 0.16 mg/mL. Importantly, the essential oil significantly inhibited NO production evoked by LPS without cytotoxicity at concentrations up to 1.25 µL/mL in macrophages and up to 0.32 µL/mL in microglia. Furthermore, evaluation of cell viability in RAW 264.7 macrophages, BW2 microgliacells and HaCaT keratinocytes showed no cytotoxicity at concentrations up to 0.32 µL/mL. CONCLUSIONS: It was possible to find appropriate doses of A. herba-alba oil with both antifungal and anti-inflammatory activities and without detrimental effects towards several mammalian cell types. These findings add significant information to the pharmacological activity of A. herba-alba essential oil, specifically to its antifungal and anti-inflammatory therapeutic value, thus justifying and reinforcing the use of this plant in traditional medicine.

Dis-organizing centrosomal clusters: specific cancer therapy for a generic spread?

Cancer is a leading cause of mortality and the annual incidence of new cancer cases is rising worldwide. Due to the frequent development of resistance and the side effects of established anti-cancer drugs, the quest for new drugs with improved therapeutic features goes on. In contrast to cytotoxic chemotherapy of the past, the concept of targeted chemotherapy attempts to increase specificity of therapy by attacking tumor-related mechanisms. A novel emerging treatment concept represents the inhibition of centrosomal clustering. The centrosome regulates mitotic spindle formation assuring uniform separation of chromosomes to daughter cells. Many tumors contain supernumerary centrosomes, which contribute to aneuploidy induction via multipolar mitotic spindle formation. As spindle multipolarity leads to cell death, tumor cells developed centrosomal clustering mechanism to prevent multipolar spindle formation by coalescence of multiple centrosomes into two functional spindle poles. Inhibition of centrosome clustering represents a novel strategy for drug development and leads to the formation of multipolar spindles and subsequent cell death. In the present review, we report advances in understanding the biology of centrosomal clustering as well as enlist compounds capable of inducing the formation of multipolar spindles such as indolquinolizines, integrin-linked kinase inhibitors (QLT-0267), noscapinoids (EM011), phthalamide derivatives (TC11), griseofulvin, phenanthridines (PJ-34), CCC1-01, CW069 GF-15, colcemid, nocodazole, paclitaxel, and vinblastine. We also present in silico result of compounds that bind to γ-tubulin under the ambit of centrosomal clustering inhibition. We observed maximum binding efficacy in GF-15, CW069, paclitaxel and larotaxel with GF-15 exhibiting least energy of -8.4 Kcal/mol and 0.7 µM Pki value.

Induction of cholesterol biosynthesis by archazolid B in T24 bladder cancer cells.

BACKGROUND: Resistance of cancer cells towards chemotherapeutics represents a major cause of therapy failure. The objective of our study was to evaluate cellular defense strategies in response to the novel vacuolar H(+)-ATPase inhibitor, archazolid B. EXPERIMENTAL APPROACH: The effects of archazolid B on T24 bladder carcinoma cells were investigated by combining "omics" technologies (transcriptomics (mRNA and miRNA) and proteomics). Free cholesterol distribution was determined by filipin staining using flow cytometry and fluorescence microscopy. Flow cytometry was performed for LDLR surface expression studies. Uptake of LDL cholesterol was visualized by confocal microscopy. SREBP activation was determined performing Western Blotting. The efficiency of archazolid B/fluvastatin combination was tested by cytotoxicity assays. RESULTS: Archazolid B led to accumulation of free cholesterol within intracellular compartments and drastic disturbances in cholesterol homeostasis resulting in activation of SREBP-2 (sterol regulatory element-binding protein 2) and up-regulation of target genes including HMGCR (HMG-CoA reductase), the key enzyme of cholesterol biosynthesis. LDLR surface expression was reduced and LDL uptake was completely inhibited after 24h, indicating newly synthesized cholesterol to be the main source of cholesterol in archazolid B treated cells. By combining archazolid B with the HMGCR inhibitor fluvastatin, cholesterol was reduced and cell viability decreased by about 20% compared to archazolid B treatment alone. CONCLUSIONS: Our study revealed cholesterol biosynthesis as an important resistance mechanism in T24 cells after archazolid B treatment. The combination of archazolid B with statins may be an attractive strategy to potentiate archazolid B induced cell killing by affecting cholesterol biosynthesis.

Cytotoxicity of novel sulfanilamides towards sensitive and multidrug-resistant leukemia cells.

Novel sulfa Schiff bases were synthesized and characterized by a reaction between aromatic sulfonamides and aromatic aldehydes or heterocyclic ketones in equimolar ratios. Their cytotoxicity was evaluated by the resazurin assay towards human sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cells. Three of the tested compounds viz., 4-(anthracen-9-ylmethyleneamino)-N-(pyrimidin-2-yl)benzenesulfonamide (4), 4-(anthracen-9- ylmethyleneamino)benzenesulfonamide, (5) and 4-((3-phenylallylidene)amino)benzene-sulfonamide, (6) were cytotoxic (IC50 values: 5.38-19.96 µM). CEM/ADR5000 cells were not cross-resistant to these compounds, indicating activity against otherwise drug-resistant tumors. Compound 6 inhibited P-glycoprotein by increasing doxorubicin accumulation and reducing expression of P-glycoprotein in CEM/ADR5000 cells. A human P-glycoprotein homology model was used for molecular docking studies. Compound 6 and verapamil (a well-known P-glycoprotein inhibitor) docked with similar binding energies to the same binding pocket.

Molecular determinants of cancer cell sensitivity and resistance towards the sesquiterpene farnesol.

Farnesol is a non-cyclic sesquiterpene (isoprenoid) found in the essential oils of many plants. In cancer biology, farnesylation of mutated Ras oncoproteins allows the proteins to dock to the membrane and be functionalized. Therefore, farnesyltransferase is a target for drug development to inhibit Ras. Farnesol exhibits cytotoxic activity against tumor cells in vitro and in vivo, implying that novel treatment strategies may be devised independent of Ras farnesylation. Tumors frequently develop resistance towards standard chemotherapies, and thus novel agents are urgently required that bypass the cross-resistance evoked by established anticancer drugs. We investigated whether classical mechanisms of drug resistance such as ATP-binding cassette transporters (P-glycoprotein/MDR1, MRP1, BCRP), the tumor suppressor gene TP53, and the oncogene EGFR play a role in the response of tumor cells to farnesol. Remarkably, none of these genes conferred resistance to farnesol, indicating that this compound may be useful for the treatment of otherwise drug-resistant and refractory tumors expressing these mechanisms of resistance. Furthermore, we applied a pharmacogenomic approach to explore molecular determinants of sensitivity and resistance to farnesol. Among the candidates were genes involved in apoptosis (STAB2, NUMBL), regulation of transcription (CDYL, FOXA2) and diverse other functional groups (INE1, CTRL, MRS2, NEB, LMO7, C9orf3, EHBP1). The fact that these genes are not associated with resistance to traditional anticancer drugs suggests farnesol may possess a novel mechanism of action, and consequently might bypass drug resistance to established chemotherapeutics.

Mechanisms of herb-induced nephrotoxicity.

Herbal therapies gained much popularity among the general public, but compared to therapies approved by official authorities, toxicological studies are frequently not available for them. Hence, there may be inherent risks and the kidneys may be especially vulnerable to toxic effects. Herbs may induce nephrotoxicity by induction of apoptosis. High oxalate contents in Star fruit (Averrhoa carambola L.) may induce acute nephropathy. Triptolide from Thunder God Vine (Triperygium wilfordii Hook) is a diterpenoid epoxide with induces reactive oxygen species and nephrotubular apoptosis. Cranberry juice is discussed as promoter of kidney stone formation (nephrolithiasis). Abuse of guaifenesin from Roughbark (Guaicum officinale L.) increases stone formation. Aristolochia acids from Aristolochia fangchi Y.C.Wu ex L.D. Chow & S.M. Hwang causes the well-known aristolochic acid nephropathy and carcinogenesis by DNA adduct formation. Carboxyatractyloside from Impila (Callilepsis laureola DC.) inhibits mitochondrial ATP synthesis. Acute allergic interstitial nephritis was diagnosed after intake of Peruvian Cat's claw (Uncaria tomentosa Willd. DC.). Whether or not Willow Bark (Salix alba L.) induces analgesic nephropathwy is a matter of discussion. Other herbal therapies are considered to affect the rennin-angiotensisn-aldosterone (RAA) system Ephedra sinica Stapf with its ingredient ephedrine. Devil's Claw (Harpagophytum procumbens DC. Ex Meisn.) and licorice (Glycyrrhiza glabra L.) may inhibit major renal transport processes needed for filtration, secretion, and absorption. Strategies to minimize nephrotoxicity include (1) quality control and standardization of herbal products, (2) research on the molecular modes of action to better understand pathophysiological mechanisms of herbal products as well as (3) clinical trials to demonstrate efficacy and safety.

Tumor-specific blood serum factors as determinants of tumor growth.

In the present review, we focus on the importance of blood serum factors for tumor growth in vivo. Data from mice experiments indicate the existence of serum factors, which increase the mitotic index of Ehrlich carcinoma cells from 15 to 80%. The impaired production of these factors increases the life span of tumor-bearing animals from 14-20 days to 90 days. Blocking the production of tumor-specific factors causes the complete regression of already developed Ehrlich carcinoma. These serum factors do not affect the malignant carcinoma cells in vitro. We identified serpins as tumor-specific serum factors. Experimental evidence suggests that serpins are not only essential for tumor growth. Serpins are also involved in the regeneration of normal tissues, such - as adipose tissue, recurrence after cosmetic operations (liposuction), inhibiting rejection after liver transplantation, protection of parasitic flat worms living in host tissues and organs etc. We conclude that the inhibition ofserum factors may represent attractive novel strategies for the prevention and treatment of relapsed cancers.

Signal transduction pathways of the epidermal growth factor receptor in colorectal cancer and their inhibition by small molecules.

While prognostic factors can help to classify the standard risk of subpopulations of patients with the same tumor entity, it is still not possible to predict the response of individual patients to specific therapies. The reason for such wide variation in cancer therapy responses remains largely unknown. The field of chemotherapy is currently undergoing a paradigm shift from classical cytotoxic chemotherapy to targeted therapy in order to kill tumor cells more efficiently with fewer side effects on normal tissue. In the present review, we focus on colorectal carcinoma, which is one of the most frequent tumor types worldwide and represents a leading cause of cancer-related deaths. The signaling pathways downstream of epidermal growth factor receptor (EGFR) are central to the biology of colorectal cancer. A considerable achievement during the past years was the development of targeted therapies against EGFR using monoclonal antibodies and small molecule inhibitors. Two major pathways mediate signal transduction through EGFR: the RAS/RAF/MAPK/ERK and the PI3K/AKT/ PTEN/mTOR pathways. Sometimes, predictive biomarkers can provide information on the expected response of tumors to standard chemotherapy. Such molecular markers for EGFR-targeted treatment have been described. However, disease progression and resistance towards EGFR-directed drugs frequently develop due to mutations in genes downstream of EGFR. In this review, we describe the mechanisms by which colorectal cancers gain resistance against EGFR-targeted therapies as well as strategies to bypass mutationinduced resistance in these two signaling pathways.

Bioinformatic and experimental fishing for artemisinin-interacting proteins from human nasopharyngeal cancer cells.

Determining interacting cellular partners of drugs by chemical proteomic techniques is complex and tedious. Most approaches rely on activity-based probe profiling and compound-centric chemical proteomics. The anti-malarial artemisinin also exerts profound anti-cancer activity, but the mechanisms of action are incompletely understood. In the present investigation, we present a novel approach to identify artemisinin-interacting target proteins. Our approach overcomes usual problems in traditional fishing procedures, because the drug was attached to a surface without further chemical modification. The proteins identified effect among others, cell cycle arrest, apoptosis, inhibition of angiogenesis, disruption of cell migration, and modulation of nuclear receptor responsiveness. Furthermore, a bioinformatic approach confirmed experimentally identified proteins and suggested a large number of other interacting proteins. Theoretically predicted interaction partners may serve as a starting point to complete the whole set of proteins binding artemisinin.

[Anticancer activity of Salvia officinalis essential oil against HNSCC cell line (UMSCC1)]. / Krebshemmende Wirkung des ätherischen Salbei-Öls auf eine Plattenepithelzellkarzinom-Zelllinie der Mundhöhle (UMSCC1).

BACKGROUND: Every year there are several hundred thousand new cases of oral cancer worldwide. Clinical oncology is still challenged by toxicity and side effects of multimodal therapy strategies in which is associated with poor prognosis for patients. There is an urgent necessity to develop novel therapy strategies. As the majority of anticancer drugs are of natural origin, natural products represent a valuable source for the identification and development of novel treatment options for cancer. The aim of this investigation was to study the cytotoxicity of Salvia officinalis L. (sage) essential oil. METHODS: Salvia officinalis essential oil was gained by aqueous extraction from plant material and subsequently analyzed by gas chromatography. The cytotoxicity of the essential oil on the squamous human cell carcinoma cell line of the oral cavity (UMSCC1) was assessed with the XTT assay. These experiments revealed the half maximal inhibitory concentration (IC(50)) of the essential oil. It was used in the microarray-based analysis of gene expression of UMSSC1 cells. The results were submitted to a signaling pathway analysis. RESULTS: The main constituents of Salvia officinalis essential oil include the monoterpenes thujone, ß-pinene, and 1,8-cineol. Low concentrations of the essential oil increased vitality of the UMSCC1 cells. Beyond the concentration of the IC(50) of 135 µg/ml, sage essential oil reduced UMSSC1 cells viability to a minimum. In the microarray gene expression analysis, genes involved in cancer, cellular growth and proliferation, cell death, cell morphology, cell cycle, gene expression, and DNA repair were the most prominent. The three most significantly regulated pathways by sage were aryl hydrocarbon receptor signaling, cell cycle (G1/S checkpoint) regulation, and p53 signaling. CONCLUSION: To the best of our knowledge, this study suggests for the first time the ability of Salvia officinalis essential oil to inhibit human HNSCC cell growth. The therapeutic potential of sage essential oil might exceed that of its common use in otorhinolaryngology.

Wogonin and related natural flavones are inhibitors of CDK9 that induce apoptosis in cancer cells by transcriptional suppression of Mcl-1.

The wogonin-containing herb Scutellaria baicalensis has successfully been used for curing various diseases in traditional Chinese medicine. Wogonin has been shown to induce apoptosis in different cancer cells and to suppress growth of human cancer xenografts in vivo. However, its direct targets remain unknown. In this study, we demonstrate for the first time that wogonin and structurally related natural flavones, for example, apigenin, chrysin and luteolin, are inhibitors of cyclin-dependent kinase 9 (CDK9) and block phosphorylation of the carboxy-terminal domain of RNA polymerase II at Ser(2). This effect leads to reduced RNA synthesis and subsequently rapid downregulation of the short-lived anti-apoptotic protein myeloid cell leukemia 1 (Mcl-1) resulting in apoptosis induction in cancer cells. We show that genetic inhibition of Mcl-1 or CDK9 expression by siRNA is sufficient to mimic flavone-induced apoptosis. Pull-down and in silico docking studies demonstrate that wogonin directly binds to CDK9, presumably to the ATP-binding pocket. In contrast, wogonin does not inhibit CDK2, CDK4 and CDK6 at doses that inhibit CDK9 activity. Furthermore, we show that wogonin preferentially inhibits CDK9 in malignant compared with normal lymphocytes. Thus, our study reveals a new mechanism of anti-cancer action of natural flavones and supports CDK9 as a therapeutic target in oncology.

Inhibition of tumor angiogenesis by antibodies, synthetic small molecules and natural products.

Cancer remains one of the major causes of death worldwide. The switch to pathological angiogenesis is a key process in the promotion of cancer and consequently provides several new and promising targets to anticancer therapy. Thus, antagonizing angiogenesis cuts off the tumor's oxygen and nutrition supply. This review focuses on angiogenesis inhibitors as option for cancer treatment. Modes of action, adverse effects, mechanisms of resistance as well as new developments are highlighted. One approach in angiogenesis inhibition is intermitting the further VEGF (vascular endothelial growth factor) signal pathway with monoclonal antibodies. Bevacizumab is a highly specific recombinant humanized monoclonal IgG antibody targeting VEGF-A. An efficient antitumor therapy demands more specific antibodies that affect other signal molecules besides VEGF-A, which is in the focus of current research. In addition to antagonizing VEGF, there are also small molecules that inhibit receptor tyrosine kinases (RTKs). Many RTK inhibitors have been described, which exhibit different specificity profiles. The question, whether highly specific antagonists are necessary remains open, because other affected RTKs may also represent growth factor receptors that are essential for tumor growth. Therefore their inhibition may also contribute to anticancer activity. Secondary plant metabolites represent templates for the development of new small molecules. The identification of new drugs from plants has a long and successful history. There is convincing evidence for the beneficial effect of phytochemicals on cancer-related pathways, particularly with regard to anti-angiogenesis. Plant phenolics are the most important category of phytochemicals, including flavanoids. Prominent phytochemicals affecting different pathways of angiogenesis are green tea polyphenols (epigallocatechin gallate) and soy bean isoflavones (genistein).

Strategies for overcoming chemotherapy resistance in enterohepatic tumours.

When considered together, enterohepatic tumours, i.e., those affecting the liver, the biliary tree and gallbladder and the intestine, constitute the first cause of death due to cancer. Although in many cases surgery and radiotherapy are efficacious, these therapeutic strategies cannot always be implemented. Moreover, even when the removal of tumours is possible, pre- and post-operative pharmacological adjuvant regimens are often needed. However, one important limitation to the use of cytostatic drugs to treat enterohepatic tumours is that they generally exhibit marked refractivity to currently available pharmacological approaches. In addition, most of them increase their chemoresistance during treatment. In view of the high refractivity of these tumours to anti-cancer drugs and the existence of undesirable side effects, both of which are drawbacks in the available chemotherapy, several novel therapeutic approaches have been devised. The purpose of the present review is to offer some insight into the different types of strategies that have already been evaluated and incorporated into clinical practice, such as therapies based on the use of molecular targets, as well as into the approaches that are still under experimental development, such as the chemosensitization of cancer cells, genetic manipulation of tumour or host cells, and cell-specific enhancement of intracellular concentrations of the active agent by efficient targeting of pro-drugs or by using inhibitors of efflux pumps.

Identification of serpin (alpha-1-antitrypsin) as serum growth inhibitory factor in murine ehrlich carcinoma by proteomics.

It is well established that serum factors play a role in relapse of tumor diseases after removal of the primary tumor. The molecular nature of these factors and their mechanism of action remain unknown. We focused on host-related mechanisms to identify tumor-specific serum factors of mice bearing Ehrlich carcinoma, which have the potential to confer resistance towards tumor development. An experimental model was used, where we incubated isolated immune cells (peritoneal cells (PCs) and splenic lymphocytes (SLCs)) in vitro with blood serum or ascitic fluid from tumor-bearing mice. Mice inoculated with PCs or SLCs previously incubated for 7 h with ascitic fluid from tumor-bearing mice did not develop tumors at a frequency of 93.1+/-5.7% (inoculation of tumor cells after two weeks) and 100% (inoculation of tumor cells three months later). This indicates that mice developed resistance towards tumor development. By fractionation of ascitic fluid and (LC/MS-MS)-driven profiling of serum proteins, we identified serpin (alpha-1-antitrypsin), which was missing from the PC-incubated fraction, indicating that this protein was bound to PCs and, thereby, purged from the protein fraction. In parallel, cathepsin L1 appeared after incubation with PCs. Serpins play a central role in the regulation of a wide variety of (patho)-physiological processes, including coagulation, fibrinolysis, inflammation, development, tumor invasion and apoptosis. Furthermore, serpins may protect parasites against the immune systems of the host. Taken together, it can be hypothesized that serpin represents a tissue- and tumor-specific anti-proteinase.

Natural products in structure-assisted design of molecular cancer therapeutics.

Since the late 1990's, novel insights into molecular biology and carcinogenesis enabled the rational design of mechanism-based anticancer therapeutics. The large number of natural product (NP)-derived drugs currently under clinical evaluation and the recent approval of temsirolimus (Torisel) as a first mTOR protein kinase inhibitor indicate that NPs have to be considered not only as a seminal source of cytotoxic, but also as a source of molecularly targeted agents. Whereas molecular modeling is well established as an important and successful method to discover and rationalize bioactivities in medicinal chemistry research, its application has also proven to be also a powerful tool in the field of NPs. This review highlights the impact of computer-assisted approaches on NPs as molecularly targeted anticancer drugs. Examples of applications are provided focusing on innovative targets such as protein kinases, tumour vasculature, epigenetic modulators, heat shock protein (Hsp) 90, and direct apoptosis enhancers.

Trypanosomatid parasites causing neglected diseases.

Parasitic diseases such as Kala azar (visceral leishmaniasis), Chagas disease human (American trypanosomiasis) and African sleeping sickness (African trypanosomiasis) are affecting more than 27 million people worldwide. They are categorized amongst the most important neglected diseases causing approximately 150,000 deaths annually. As no vaccination is available, treatment is solely dependent on chemotherapeutic drugs. This review provides a comprehensive insight into the treatment of Kala azar, Chagas disease and African sleeping sickness. In addition to established drugs, novel small molecule- based therapeutic approaches are discussed. Drugs currently used for the treatment of Kala azar include pentavalent antimonials, Amphotericin B, Miltefosine, and Paromomycin. Liposomal formulations such as AmBisome provide promising alternatives. Furthermore, antiproliferative compounds might open new avenues in Kala azar treatment. Regarding Chagas disease, chemotherapy is based on two drugs, Nifurtimox and Benznidazole. However, sequencing of T. cruzi genome in the year 2005 raises a hope for new drug targets. Proteases, sterols and sialic acids are potential promising drug targets. Suramin, Pentamidine, Melarsporol and Eflornithine are well-established drugs to treat African sleeping sickness. New treatment options include combination therapy of Eflornithine and Nifurtimox, a Chagas disease therapeutic.. However, all approved chemotherapeutic compounds for trypanosomatid diseases suffer from high toxicity. Further, increasing resistance limits their efficacy and compliance.