AKT and p21 WAF1/CIP1 as potential genistein targets in BRCA1-mutant human breast cancer cell lines.

BRCA1 acts as a tumour suppressor and germ-line mutations within this gene are found in a large proportion of families with breast cancer. The aim of our study was to unravel the mechanism of action of genistein, the major soy phytoestrogen, in BRCA1-mutant human breast cancer cell lines. Four breast cancer cell lines were studied for their response to genistein, three of them harbouring different mutations within the BRCA1 gene (HCC1937, SUM149 and SUM1315 cells) and the MDA-MB-231 cell line, which expresses a functional BRCA1 protein. We showed that genistein inhibits proliferation and induces apoptosis more efficiently in BRCA1-mutant cells than in cells expressing wild-type BRCA1 protein. Increased AKT and decreased p21(WAF1/CIP1) protein levels could explain the relative resistance to genistein elicited by cells with wild-type BRCA1. BRCA1-mutant breast cancer cells are highly sensitive to genistein treatment and p21(WAF1/CIP1) and AKT could be genistein targets in these cells.

Metabolomics in evaluation of glucose disorders.

PURPOSE OF REVIEW: Recent advances in metabolomic tools now permit to characterize dysregulated metabolic pathways in various diseases associated with the identification of sensitive and specific early responding biomarkers that are critical both for the diagnosis of the type of insult as well as for the selection and evaluation of therapy. RECENT FINDINGS: This short review describes progresses made in analytical science and their applications in the field of glucose disorders. Recent studies focused mainly on type 2 diabetes both in human and animal models in order to validate early biomarkers and effects of drugs on disease progression. The potential of using the metabolomic approach was also demonstrated for diagnosing diabetic complications such as diabetic nephropathy. SUMMARY: In addition to its application in the discovery of disease biomarkers, metabolomics can contribute to the elucidation of pathophysiological mechanisms.

Breast cancer cell response to genistein is conditioned by BRCA1 mutations.

Soy phytoestrogens, among which genistein, seem to protect from breast cancer development. In order to study the role of the breast tumour suppressor BRCA1 in response to genistein, we used a new breast cancer cell model: the SUM1315MO2 cell line carrying the 185delAG BRCA1 mutation, which we stably transfected with a plasmid encoding wild-type BRCA1. We showed that growth of BRCA1 mutant cells was strongly inhibited by genistein whereas it only had a weak effect in cells expressing wild-type BRCA1 protein. BRCA1 mutant cells hypersensitivity could be linked to higher expression of ERbeta gene, which suggests that genistein may be an efficient inhibitor of cancer development in BRCA1 mutant breast cancer cells.

Amino acid limitation regulates the expression of genes involved in several specific biological processes through GCN2-dependent and GCN2-independent pathways.

Evidence has accumulated that amino acids play an important role in controlling gene expression. Nevertheless, two components of the amino acid control of gene expression are not yet completely understood in mammals: (a) the target genes and biological processes regulated by amino acid availability, and (b) the signaling pathways that mediate the amino acid response. Using large-scale analysis of gene expression, the objective of this study was to gain a better understanding of the control of gene expression by amino acid limitation. We found that a 6 h period of leucine starvation regulated the expression of a specific set of genes: 420 genes were up-regulated by more than 1.8-fold and 311 genes were down-regulated. These genes were involved in the control of several biological processes, such as amino acid metabolism, lipid metabolism and signal regulation. Using GCN2-/- cells and rapamycin treatment, we checked for the role of mGCN2 and mTORC1 kinases in this regulation. We found that (a) the GCN2 pathway was the major, but not unique, signaling pathway involved in the up- and down-regulation of gene expression in response to amino acid starvation, and (b) that rapamycin regulates the expression of a set of genes that only partially overlaps with the set of genes regulated by leucine starvation.

Acetaminophen recruits spinal p42/p44 MAPKs and GH/IGF-1 receptors to produce analgesia via the serotonergic system.

The mechanism of action of acetaminophen is currently widely discussed. Direct inhibition of cyclooxygenase isoforms remains the commonly advanced hypothesis. We combined behavioral studies with molecular techniques to investigate the mechanism of action of acetaminophen in a model of tonic pain in rats. We show that acetaminophen indirectly stimulates spinal 5-hydroxytryptamine (5-HT)1A receptors in the formalin test, thereby increasing transcript and protein levels of low-affinity neurotrophin receptor, insulin-like growth factor-1 (IGF-1) receptor alpha subunit, and growth hormone receptor and reducing the amount of somatostatin 3 receptor (sst3R) mRNA. Those cellular events seem to be important for the antinociceptive activity of acetaminophen. Indeed, down-regulation of sst3R mRNA depends on acetaminophen-elicited, 5-HT1A receptor-dependent increase in neuronal extracellular signal-regulated kinase 1/2 (ERK1/2) activities that mediate antinociception. In addition, spinal growth hormone (GH) and IGF-1 receptors would also be involved in the antinociceptive activity of the analgesic at different degrees. Our results show the involvement of specific 5-HT1A receptor-dependent cellular events in acetaminophen-produced antinociception and consequently indicate that inhibition of cyclooxygenase activities is not the exclusive mechanism involved. Furthermore, we propose that the mechanisms of 5-HT1A receptor-elicited antinociception and the role of the spinal ERK1/2 pathway in nociception are more intricate than suspected so far and that the GH/IGF-1 axis is an interesting new player in the regulation of spinal nociception.

Increased muscle proteolysis after local trauma mainly reflects macrophage-associated lysosomal proteolysis.

Rat gastrocnemius showed increased protein degradation (+75-115%) at 48 h after traumatic injury. Injured muscle showed increased cathepsin B activity (+327%) and mRNA encoding cathepsin B (+670%), cathepsin L (+298%), cathepsin H (+159%), and cathepsin C (+268%). In in situ hybridization, cathepsin B mRNA localized to the mononuclear cell infiltrate in injured muscle, and only background levels of hybridization were observed either over muscle cells in injured tissue or in uninjured muscle. Immunogold/electron microscopy showed specific staining for cathepsin B only in lysosome-like structures in cells of the mononuclear cell infiltrate in injured muscle. Muscle cells were uniformly negative in the immunocytochemistry. Matrix metalloproteinase-9 (granulocyte-macrophage gelatinase) mRNA and activity were not present in uninjured muscle but were expressed after trauma. There was no activation of the ATP-ubiquitin-proteasome-dependent proteolytic pathway in injured muscle, by contrast to diverse forms of muscle wasting where the activity of this system and the expression of genes encoding ubiquitin and proteasome elements rise. These results suggest that proteolytic systems of the muscle cells remain unstimulated after local injury and that lysosomal enzymes of the inflammatory infiltrated cells are likely to be the major participant in protein catabolism associated with local trauma.