Search

In invertebrates and amphibians, informational macromolecules in egg cytoplasm are organized to provide direction to the formation of embryonic lineages, but it is unclear whether vestiges of such prepatterning exist in mammals. Here we examined whether twin blastomeres from 2-cell stage mouse embryos differ in mRNA content. mRNA from 26 blastomeres derived from 13 embryos approximately mid-way through their second cell cycle was subjected to amplification. Twenty amplified samples were hybridized to arrays. Of those samples that hybridized successfully, 12 samples in six pairs were used in the final analysis. Probes displaying normalized values >0.25 (n = 4573) were examined for consistent bias in expression within blastomere pairs. Although transcript content varied between both individual embryos and twin blastomeres, no consistent asymmetries were observed for the majority of genes, with only 178 genes displaying a >1.4-fold difference in expression across all six pairs. Although class discovery clustering showed that blastomere pairs separated into two distinct groups in terms of their differentially expressed genes, when the data were tested for significance of asymmetrical expression, only 39 genes with >1.4-fold change ratios in six of six blastomere pairs passed the two-sample t-test (P < 0.05). Transcripts encoding proteins implicated in RNA processing and cytoskeletal organization were among the most abundant, differentially distributed mRNA, suggesting that a stochastically based lack of synchrony in cell cycle progression between the two cells might explain at least some and possibly all of the asymmetries in transcript composition.

25-Hydroxyvitamin D(3) (25(OH)D(3)) is a prohormone and a major vitamin D metabolite. The discovery of (25(OH)D(3)) 1 alpha-hydroxylase in many vitamin D target organs has yielded an increased interest in defining the role(s) of 25(OH)D(3) in these tissues. The etiology of cancer appears to be complex and multi-factorial. Cellular stress (e.g., DNA damage, hypoxia, oncogene activation) has been identified as one of the key factors responsible for initiating the carcinogenesis process. In this study, we investigated whether 25(OH)D(3) protects breast epithelial cells from cellular stress using an established breast epithelial cell line MCF12F. To better elucidate the role of 25(OH)D(3) in the stress response, we used multiple in vitro stress models including serum starvation, hypoxia, oxidative stress, and apoptosis induction. Under all these stress conditions, 25(OH)D(3) (250 nmol/L) treatment significantly protected cells against cell death. Low-serum stress induced p53 expression accompanied with downregulation of PCNA, the presence of 25(OH)D(3) consistently inhibited the alteration of p53 and PCNA, suggesting that these molecules were involved in the stress process and may be potential target genes of 25(OH)D(3). miRNA microarray analysis demonstrated that stress induced by serum starvation caused significant alteration in the expression of multiple miRNAs including miR182, but the presence of 25(OH)D(3) effectively reversed this alteration. These data suggest that there is a significant protective role for 25(OH)D(3) against cellular stress in the breast epithelial cells and these effects may be mediated by altered miRNA expression., ((c) 2010 Wiley-Liss, Inc.)

An emphasis in early detection and more effective treatments has decreased the mortality rate of breast cancer. Despite this decrease, breast cancer continues to be the leading cause of death among women between 40 and 55 years of age and is the second overall cause of death among women. Hence, the aim of the present study was to assess the therapeutic efficacy of deguelin, a rotenoid isolated from several plant species, which has been reported to have chemopreventive and/or chemotherapeutic effects in skin, mammary, colon, and lung cancers. The effect of deguelin on cell proliferation was evaluated using four human breast carcinoma cell lines (MCF-7, BT474, T47D, and MDA-MB-231) by cell count and MTT. Moreover, apoptosis was evaluated by acridine/ethidium staining and DNA laddering. Gene expression changes following deguelin treatment in MDA-MB-231 cells was assessed through microarray analysis. Deguelin at 1 mumol/L was found to inhibit the growth of the breast cancer cell lines tested with a range of 37% to 87%. The highest inhibition was noted for the MDA-MB-231 cell line (MDA-MB-231>BT474>MCF7>T47D>MCF12F). An arrest at the S phase of the cell cycle and apoptosis were shown in the MDA-MB-231 cells treated with deguelin. The microarray profile indicated differential expression of two independent pathways, including clusters of apoptosis and Wnt/beta-catenin signaling genes in cells as a result of deguelin treatment. These studies support the antiproliferative effects of deguelin in human breast cancer cells and, perhaps more importantly, illustrate novel actions by deguelin in the Wnt signaling pathway.