RNA sequencing reveals two major classes of gene expression levels in metazoan cells

The expression level of a gene is often used as a proxy for determining whether the protein or RNA product is functional in a cell or tissue. Therefore, it is of fundamental importance to understand the global distribution of gene expression levels, and to be able to interpret it mechanistically and functionally. Here we use RNA sequencing (RNA‐seq) of mouse Th2 cells, coupled with a range of other techniques, to show that all genes can be separated, based on their expression abundance, into two distinct groups: one group comprised of lowly expressed and putatively non‐functional mRNAs, and the other of highly expressed mRNAs with active chromatin marks at their promoters. These observations are confirmed in many other microarray and RNA‐seq data sets of metazoan cell types.     

Effect of overexpression of estrogen receptors in osteoblasts

Summary Our study focused on investigating the mechanism of action of estrogen in regulating p53 levels within osteoblasts. In the studies reported here, we attempted to understand the role of estrogen receptors, ER-alpha and ER-beta, in the regulation of p53 and osteoblast differentiation. We stably expressed ER-alpha and ER-beta in ROS 17/2.8 cells and isolated several single cell clones. These clones were initially characterized for expression of the exogenous receptors, and representative clones from each type were chosen for further analyses. Cell proliferation, alkaline phosphatase activity, and the viability of these clones in culture were tested. The cells expressing exogenous ER-alpha exhibited more differentiated characteristics than cells expressing ER-beta. Morphologically, ER-beta-overexpressing cells were more rounded than the ER-alpha-overexpressing cells, which were more elongated and fibroblastic in appearance. The ER-beta-expressing cells had a higher survival and growth rate when compared with ER-alpha cells. The ER-alpha clones were not as viable as ER-beta clones, and some of the ER-alpha cell lines showed signs of senescence, with an increase in senescence-associated (SA) galactosidase activity. The basal levels of p53 functional activity were higher in cells expressing ER-alpha as was protein expression of the p53-regulated gene p21. The significance of these receptors to osteoblast differentiation and p53 regulation is discussed.     

Furanodienone inhibits cell proliferation and survival by suppressing ERα signaling in human breast cancer MCF-7 cells

Estrogen receptor alpha (ERα) plays an important role in the development and progression of breast cancer and thus the attenuation of ERα activities is a promising treatment strategy. Furanodienone is one of the main bioactive chemical components of Rhizoma Curcumae which is commonly used in Chinese medicine for the treatment of cancer. In this study, we investigated the effects of furanodienone on human breast cancer MCF‐7, T47D, and MDA‐MB‐231 cells. Our results showed that furanodienone could inhibit MCF‐7, T47D, and MDA‐MB‐231 cells proliferation in a dose (10–160 µM) dependent manner. ERα‐negative MDA‐MB‐231 cells were less sensitive to furanodienone than ERα‐positive MCF‐7 and T47D cells. Furanodienone could effectively block 17β‐estradiol (E2)‐stimulated MCF‐7 cell proliferation and cell cycle progression and induce apoptosis evidenced by the flow cytometric detection of sub‐G1 DNA content and the appearance of apoptotic nuclei after DAPI staining. Furanodienone specifically down‐regulated ERα protein and mRNA expression levels without altering ERβ expression. Furanodienone treatment inhibited E2‐stimulation of estrogen response element (ERE)‐driven reporter plasmid activity and ablated E2‐targeted gene (e.g., c‐Myc, Bcl‐2, and cyclin D1) expression which resulted in the inhibition of cell cycle progression and cell proliferation, and in the induction of apoptosis. Knockdown of ERα in MCF‐7 cells by ERα‐specific siRNA decreased the cell growth inhibitory effect of furanodienone. These findings suggest that effects of furanodienone on MCF‐7 cells are mediated, at least in part, by inhibiting ERα signaling. J. Cell. Biochem. 112: 217–224, 2011. © 2010 Wiley‐Liss, Inc.