Analysis of the ERK1,2 transcriptome in mammary epithelial cells

Abstract

MAPK (mitogen-activated protein kinase) pathways constitute major regulators of cellular transcriptional programmes. We analysed the ERK1,2 (extracellular-signal-regulated kinase 1,2) transcriptome in a non-transformed MEC (mammary epithelial cell) line, MCF-12A, utilizing rAd MEK1EE, a recombinant adenovirus encoding constitutively active MEK1 (MAPK/ERK kinase 1). rAd MEK1EE infection induced morphological changes and DNA synthesis which were inhibited by the MEK1,2 inhibitor PD184352. Hierarchical clustering of data derived from seven time points over 24 h identified 430 and 305 co-ordinately up-regulated and down-regulated genes respectively. c-Myc binding sites were identified in the promoters of most of these up-regulated genes. A total of 46 candidate effectors of the Raf/MEK/ERK1,2 pathway in MECs were identified by comparing our dataset with previously reported Raf-1-regulated genes. These analyses led to the identification of a suite of growth factors co-ordinately induced by MEK1EE, including multiple ErbB ligands, vascular endothelial growth factor and PHRP (parathyroid hormone-related protein). PHRP is the primary mediator of humoral hypercalcaemia of malignancy, and has been implicated in metastasis to bone. We demonstrate that PHRP is secreted by MEK1EE-expressing cells. This secretion is inhibited by PD184352, but not by ErbB inhibitors. Our results suggest that, in addition to anti-proliferative properties, MEK1,2 inhibitors may be anti-angiogenic and possess therapeutic utility in the treatment of PHRP-positive tumours.

Inactivation of the Mitogen-Activated Protein Kinase Pathway as a Potential Target-Based Therapy in Ovarian Serous Tumors with KRAS or BRAF Mutations

“…Our finding of upregulation of TRAIL after MAPK inhibition in ovarian tumor cells with mutations in KRAS/BRAF but not in those with wild-type sequences suggests that CI-1040 induced apoptosis is related to the expression of TRAIL. This finding complements a recent report showing that activation of MAPK suppressed the expression of TRAIL in nontransformed mammalian epithelial cells based on gene expression profiling using oligonucleotide expression arrays (14).…”

“…Activation of MAPK activates downstream cellular targets (12,13) including a variety of cellular and nuclear proteins. Although the function and downstream effectors of the RAS/RAF/MEK/MAPK (ERK) pathway have been recently studied (14), the biological role of this pathway in the development of ovarian serous tumors has not been explored.…”

Helicobacter pylori Induces ERK-dependent Formation of a Phospho-c-Fos·c-Jun Activator Protein-1 Complex That Causes Apoptosis in Macrophages

“…We show that H. pylori-induced phosphorylation of ERK mediates induction of c-Myc and ODC, with similar increases in mRNA and protein levels for both genes. Overexpression of constitutively active MEK1 in mammary epithelial cells has been reported to increase the levels of both c-Myc and ODC mRNA that was attenuated with ERK phosphorylation inhibitors (49). However, this study was microarray-based, without assessment of protein levels, and utilized ectopic expression rather than a biological stimulus, as we have used.…”

HOXA1-stimulated oncogenicity is mediated by selective upregulation of components of the p44/42 MAP kinase pathway in human mammary carcinoma cells

“…Another upregulated gene, IER3 (IEX-1), is an immediate upstream regulator that potentiates p44/42 MAP kinase activation in response to growth factors and is also involved in the regulation of cell death and oncogenesis (Garcia et al, 2002). In MCF-12A mammary epithelial cells, constitutive activation of p44/42 MAP kinase pathway also results in transcriptional upregulation of IER3 (Grill et al, 2004). Endothelial PAS-domain protein 1 (EPAS1) is phosphorylated by p44/42 MAP kinase pathway, and is also involved in angiogenesis of human renal carcinoma (Conrad et al, 1999).…”