The role of neurokinin-1 receptor in the microenvironment of inflammation and cancer

The recent years have witnessed an exponential increase in cancer research, leading to a considerable investment in the field. However, with few exceptions, this effort has not yet translated into a better overall prognosis for patients with cancer, and the search for new drug targets continues. After binding to the specific neurokinin-1 (NK-1) receptor, the peptide substance P (SP), which is widely distributed in both the central and peripheral nervous systems, triggers a wide variety of functions. Antagonists against the NK-1 receptor are safe clinical drugs that are known to have anti-inflammatory, analgesic, anxiolytic, antidepressant, and antiemetic effects. Recently, it has become apparent that SP can induce tumor cell proliferation, angiogenesis, and migration via the NK-1 receptor, and that the SP/NK-1 receptor complex is an integral part of the microenvironment of inflammation and cancer. Therefore, the use of NK-1 receptor antagonists as a novel and promising approach for treating patients with cancer is currently under intense investigation. In this paper, we evaluate the recent scientific developments regarding this receptor system, its role in the microenvironment of inflammation and cancer, and its potentials and pitfalls for the usage as part of modern anticancer strategies.

Nitric oxide radical scavenging active components from Phyllanthus emblica L

An activity-directed fractionation and purification process was used to identify the nitric oxide (NO) scavenging components of Phyllanthus emblica. Dried fruit rind of P. emblica was extracted with methanol and then separated into hexane, ethyl acetate, and water fractions. Among these only the ethyl acetate phase showed strong NO scavenging activity in vitro, when compared with water and hexane phases. The ethyl acetate fraction was then subjected to separation and purification using Sephadex LH-20 chromatography. Five compounds showing strong NO scavenging activity were identified by spectral methods (1H NMR, 13C NMR, and MS) and by comparison with literature values to be Gallic acid, Methyl gallate, Corilagin, Furosin, and Geraniin. In addition, HPLC identification and quantification of isolated compounds were also performed. Gallic acid was found to be a major compound in the ethyl acetate extract and Geraniin showed highest NO scavenging activity among the isolated compounds.

Transposable elements – Is there a link between evolution and cancer?

Currently, the most predominant theory concerning the formation of cancer is that it is a genetic accident. Accordingly, various agents are thought to cause DNA damage which then subsequently activates oncogenes and inactivates tumor suppressor genes. This article, however, describes a theory that interprets cancer as a misguided adaptation. Stressors, which cannot be compensated for with the usual cell possibilities might arouse evolutionary mechanisms intended to create new protein variants. One of these is the activation of transposable elements which leads to a reformatting of the genome. The result of this process is either a cell that survives very well under stress (and will, therefore, never be detected), a dead cell (in case the process is ineffective), or a more or less abnormal and harmful cell that builds up a new but cancerous organ. This theory explains the complex genetic alterations which are present in almost all cancer cells. It also explains the action of non-mutagenic carcinogens. As part of the reformatting process of the cancer cell genome, activation of oncogenes and inactivation of tumor suppressor genes are not stochastic events but the result of an unlucky genomic composition.

The evaluation of nitric oxide scavenging activity of certain Indian medicinal plants in vitro: a preliminary study

The plant extracts of 17 commonly used Indian medicinal plants were examined for their possible regulatory effect on nitric oxide (NO) levels using sodium nitroprusside as an NO donor in vitro. Most of the plant extracts tested demonstrated direct scavenging of NO and exhibited significant activity. The potency of scavenging activity was in the following order: Alstonia scholaris > Cynodon dactylon > Morinda citrifolia > Tylophora indica > Tectona grandis > Aegle marmelos (leaf) > Momordica charantia > Phyllanthus niruri > Ocimum sanctum > Tinospora cordifolia (hexane extract) = Coleus ambonicus > Vitex negundo (alcoholic) > T. cordifolia (dichloromethane extract) > T. cordifolia (methanol extract) > Ipomoea digitata > V. negundo (aqueous) > Boerhaavia diffusa > Eugenia jambolana (seed) > T. cordifolia (aqueous extract) > V. negundo (dichloromethane/methanol extract) > Gingko biloba > Picrorrhiza kurroa > A. marmelos (fruit) > Santalum album > E. jambolana (leaf). All the extracts evaluated exhibited a dose-dependent NO scavenging activity. The A. scholaris bark showed its greatest NO scavenging effect of 81.86% at 250 microg/mL, as compared with G. biloba, where 54.9% scavenging was observed at a similar concentration. The present results suggest that these medicinal plants might be potent and novel therapeutic agents for scavenging of NO and the regulation of pathological conditions caused by excessive generation of NO and its oxidation product, peroxynitrite.

Induction or suppression of SV40 amplification by genotoxic carcinogens, non-genotoxic carcinogens or tumor promoters

Carcinogens are generally classified into two groups: genotoxic and non-genotoxic. As the final product of genotoxic and non-genotoxic carcinogens is the same, i.e., a clone of genetically altered cells, it could be possible that non-genotoxic carcinogens may yield genotoxic events as a secondary result of cell toxicity having led to mitogenesis/cellular proliferation, or that genetic alterations are induced that are normally neglected in genotoxicity tests. A genetic effect with possible relevance for the ultimate mechanism of carcinogenicity is the amplification of oncogenes. In the present experiments, amplification of SV40-virus DNA in transformed CO631-cells has been measured. In this system, two genotoxic carcinogens (positive control), two non-carcinogens (negative control), and eight non-genotoxic carcinogens have been tested. With the exception of testosterone and BVDU, all substances were tested when given alone. Testosterone and BVDU were tested in combination with either MTX or AMP in the presence or absence of S9-mix. The genotoxic carcinogens TEM and 4-NQO as well as the tumor promoters TPA, coumarin, mezerein and chrysarobin were able to induce SV40 amplification when given alone. The same was for acetamide and thioacetamide. The non-carcinogens acetone and dimethylformamide were ineffective. In case of testosterone, a co-amplification effect was seen in the absence of S9-mix, and an anti-amplification effect in presence of S9-mix. The anti-recombinogen BVDU reduced the SV40 amplification effect of AMP in experiments without addition of S9-mix. In the presence of activating S9-mix, this substance was effective at lower concentrations than without S9-mix, and showed an enhanced anti-amplification effect. Similar effects of testosterone and BVDU had been observed before in respect to stimulation or suppression of recombination. These results can be used as supportive evidence for the assumption that gene amplification is mechanistically related to recombination.

Co-recombinogenic and anti-mutagenic effects of diethylhexylphthalate, inactiveness of pentachlorophenol in the spot test with mice

In in vivo experiments using the spot test with mice, diethylhexylphthalate (DEHP) was co-recombinogenic and anti-mutagenic. In two independent experiments, DEHP was able to increase in combination with ethylnitrosourea (ENU) the frequency of animals with spots of genetic relevance from about 12% (ENU alone) to about 15% (ENU+DEHP). This enhancement can be exclusively attributed to an enhancement of recombination. In historical as well as in current experiments, with astonishing accuracy, about 8% of all spots induced with ENU alone are black, near-white or twin spots, i.e., presumed products of reciprocal recombination. Under the influence of DEHP, about 20% of all colored spots were black, near-white or twin spots. These co-recombinogenic effects are very strong, considering that the low frequency of twin spots with 0.3% (historical ENU control) or 0.6% (current ENU control) after ENU treatment alone has been enhanced up to a frequency of 3%. While ENU alone induces about 14% light brown colored spots, depending exclusively on gene mutations, under the influence of DEHP the frequency was only 7%, i.e., DEHP was anti-mutagenic. Pentachlorophenol was ineffective in enhancing or reducing recombination or mutations. There was no difference between ENU and ENU+PCP treatment. Since a number of "non-genotoxic' carcinogens with tumor-promoting activities like D-limonene, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) have shown similar effects in the spot test, it is suggested that DEHP may have tumor-promoting activity in carcinogenicity tests.

The Carcinogenic Potency Database: analyses of 4000 chronic animal cancer experiments published in the general literature and by the U.S. National Cancer Institute/National Toxicology Program

The Carcinogenic Potency Database (CPDB) is an easily accessible, standardized resource of positive and negative long-term animal cancer tests. The CPDB has been published in four earlier papers that include results for approximately 4000 experiments on 1050 chemicals. This paper describes the CPDB: goals, inclusion criteria, fields of information, and published plot format. It also presents an overview of our published papers using the CPDB. The CPDB as published in plot format readily permits comparisons of carcinogenic potency and many other aspects of cancer tests, including for each experiment the species and strain of test animals, the route and duration of compound administration, dose level and other aspects of experimental protocol, histopathology and tumor incidence, TD50 (carcinogenic potency) and its statistical significance, dose response, author's opinion about carcinogenicity, and literature citation. A combined plot of all results from the four separate papers, which is ordered alphabetically by chemical, is available from L. S. Gold, in printed form or on computer tape or diskette. A computer readable (SAS) database is also available. The overview of papers includes descriptions of work on methods of estimating carcinogenic potency, reproducibility of results in near-replicate cancer tests, correlation in potency between species, ranking possible carcinogenic hazards, comparison of positivity and target organ in rats and mice, comparison of mutagens and nonmutagens, proportion of chemicals positive in animal tests, natural compared to synthetic chemicals, and mechanistic issues in interspecies extrapolation.