Mammary cancer promotion by ovarian hormones involves IGFR/AKT/mTOR signaling

In a previous study, we observed that N-methyl-N-nitrosourea (MNU)-induced mammary lesions are promoted to overt mammary cancers by exogenous administration of estradiol (E) and progesterone (P). The purpose of the present study was to identify the early molecular events occurring during the hormonal promotion of mammary carcinogenesis and persistent activation of molecular pathways responsible for tumor growth. Seven-week-old female Copenhagen (COP) rats, which are resistant to MNU-induced mammary carcinogenesis, were intraperitoneally administered a single dose of MNU (50 mg/kg body weight). Six weeks after carcinogen administration, the rats were treated with E+P, killed at 15th week and 43rd week to obtain mammary lesions and tumor tissues and the molecular analysis were performed. Quantitative RT-PCR experiments showed increased mRNA expression of Igfr, Grb2, Sos1, and Shc1 in mammary lesions and tumors. Immunoblot data also showed increased protein levels of IGFR, GRB2 and SHC1 in mammary lesions and tumors, which is in correlation with their respective RT-PCR data. Activation of AKT and ERK1/2 were up regulated in E+P treated mammary lesions and tumors. Molecular analysis of mTOR pathway proteins revealed increased phosphorylation of p70S6K and 4EBP1 in the hormone treated tumors indicating the activation of mTOR signaling. E+P treatment reduced the protein expression of BAX and increased BCL2 expression along with down regulation of active caspase 3 and 8. Together, these data demonstrate that ovarian hormones promote the lesions to mammary tumors by enhancing IGFR and Akt/mTOR signaling along with inhibition of apoptotic stimuli.     

Guanosine protects human neuroblastoma SH-SY5Y cells against mitochondrial oxidative stress by inducing heme oxigenase-1 via PI3K/Akt/GSK-3β pathway

Mitochondrial perturbation and oxidative stress are key factors in neuronal vulnerability in several neurodegenerative diseases or during brain ischemia. Here we have investigated the protective mechanism of action of guanosine, the guanine nucleoside, in a human neuroblastoma cell line, SH-SY5Y, subjected to mitochondrial oxidative stress. Blockade of mitochondrial complexes I and V with rotenone plus oligomycin (Rot/oligo) caused a significant decrease in cell viability and an increase in ROS production. Guanosine that the protective effect of guanosine incubated concomitantly with Rot/oligo abolished Rot/oligo-induced cell death and ROS production in a concentration dependent manner; maximum protection was achieved at the concentration of 1mM. The cytoprotective effect afforded by guanosine was abolished by adenosine A(1) or A(2A) receptor antagonists (DPCPX or ZM241385, respectively), or by a large (big) conductance Ca(2+)-activated K(+) channel (BK) blocker (charybdotoxin). Evaluation of signaling pathways showed that the protective effect of guanosine was not abolished by a MEK inhibitor (PD98059), by a p38(MAPK) inhibitor (SB203580), or by a PKC inhibitor (cheleritrine). However, when blocking the PI3K/Akt pathway with LY294002, the neuroprotective effect of guanosine was abolished. Guanosine increased Akt and p-Ser-9-GSK-3β phosphorylation confirming this pathway plays a key role in guanosine's neuroprotective effect. Guanosine induced the antioxidant enzyme heme oxygenase-1 (HO-1) expression. The protective effects of guanosine were prevented by heme oxygenase-1 inhibitor, SnPP. Moreover, bilirubin, an antioxidant and physiologic product of HO-1, is protective against mitochondrial oxidative stress. In conclusion, our results show that guanosine can afford protection against mitochondrial oxidative stress by a signaling pathway that implicates PI3K/Akt/GSK-3β proteins and induction of the antioxidant enzyme HO-1.     

Investigation on the surface properties of chemically modified natural fibers using inverse gas chromatography

This paper presents the application of inverse gas chromatography (IGC) technique for characterization and comparison of the surface properties of the natural fibers as reinforcement fillers in wood plastic composites. The effects of chemical modification using 1% NaOH were also studied. The fibers used for this work were Iranian cultivated eucalyptus, spruce, bagasse, and wheat straw. Chemical composition of fibers was found to be modified after treatment as characterized by Fourier transform infrared spectroscopy (FTIR). The crystallinity of fibers and the specific interaction was improved by the alkaline treatment, with more relevance to the agro-fibers. The IGC shows also a general increase in the wettability of the modified fiber when compared with the raw (unmodified) samples. Alkaline treatment achieves the best overall improvement in the properties evaluated of the agro-fibers when compared to the wood fibers.     

Behavior of myc and ras oncogenes in transformation of rat embryo fibroblasts.

The requirements for transformation of rat embryo fibroblasts (REFs) by transfected ras and myc oncogenes were explored. Under conditions of dense monolayer culture, neither oncogene was able to transform REFs on its own. However, the introduction of a ras oncogene together with a selectable neomycin resistance marker into REFs allowed killing of the normal nontransfected cells and the outgrowth of colonies of ras transformants, 10% of which survived crisis and became tumorigenic. These cells expressed greater than 10-fold-higher levels of ras p21 than tumorigenic cells cotransfected with ras and myc oncogenes. The myc oncogene similarly was unable to induce tumorigenic conversion of REFs unless especially refractile colonies of oncogene-bearing cells, produced by use of a cotransfected selectable marker, were picked and subcultured. Tumorigenic conversion of REFs by single transfected oncogenes appears to require special culture conditions and high levels of gene expression.     

Nuclear DNA content in two Sphaeriidae species from Southern Chile (Bivalvia: Veneroida)

The family Sphaeriidae is a group of cosmopolitan freshwater clams that inhabit temporary and permanent fluvial and lacustrine environments around the world. In Chile, Sphaeriidae is represented by 11 species belonging to the genera Musculium, Pisidium and Sphaerium. In this study, the nuclear DNA content (or 2C-value) of Musculium argentinum (d’Orbigny, 1835) and Pisidium llanquihuense Ituarte, 1999 was estimated for the first time. Musculium argentinum showed a 2C-value of 3.7?±?0.38?pg, whereas P. llanquihuense showed a 2C-value of 3.57?±?0.36?pg. These 2C-values are within the range previously reported for Sphaeriidae (2.35–5.7?pg), which includes diploids and polyploids, amounting to 13 of the species examined around the world. Of the cytological data available for the family, the nuclear DNA content can have a unifying role in understanding the magnitude of the chromosome polymorphisms within this polyploid complex.     

Divergent selection for skeletal malformations in chickens alters polymorphism at microsatellite loci

The objective of this study was to determine microsatellite polymorphism in Rhode Island Red (RIR) and Sussex (SX) chickens, divergently selected over six generations for high (H) or low (L) incidence of skeletal defects in embryos (30.7% for H lines, 3.7% for L lines). The polymorphism analysis covered 15 microsatellite markers within four lines (a total of 60 individuals). Eight alleles were identified as specific to H lines and six alleles as specific to L lines. The selection for skeletal malformation appears to have affected the frequency of microsatellite alleles. The experimental material examined constitutes a valuable source for identification of real genes causing skeletal defects.     

Hypotonicity induces TRPV4-mediated nociception in rat

We hypothesized that TRPV4, a member of the transient receptor family of ion channels, functions as a sensory transducer for osmotic stimulus-induced nociception. We found that, as expected for a transducer molecule, TRPV4 protein is transported in sensory nerve distally toward the peripheral nerve endings. In vivo single-fiber recordings in rat showed that hypotonic solution activated 54% of C-fibers, an effect enhanced by the hyperalgesic inflammatory mediator prostaglandin E2. This osmotransduction causes nociception, since administration of a small osmotic stimulus into skin sensitized by PGE2 produced pain-related behavior. Antisense-induced decrease in expression of TRPV4 confirmed that the channel is required for hypotonic stimulus-induced nociception. Thus, we conclude that TRPV4 can function as an osmo-transducer in primary afferent nociceptive nerve fibers. Because this action is enhanced by an inflammatory mediator, TRPV4 may be important in pathological states and may be an attractive pharmacological target for the development of novel analgesics.