Dataset Information

TDAG51 is an ERK signaling target that opposes ERK-mediated HME16C mammary epithelial cell transformation.

ABSTRACT: Signaling downstream of Ras is mediated by three major pathways, Raf/ERK, phosphatidylinositol 3 kinase (PI3K), and Ral guanine nucleotide exchange factor (RalGEF). Ras signal transduction pathways play an important role in breast cancer progression, as evidenced by the frequent over-expression of the Ras-activating epidermal growth factor receptors EGFR and ErbB2. Here we investigated which signal transduction pathways downstream of Ras contribute to EGFR-dependent transformation of telomerase-immortalized mammary epithelial cells HME16C. Furthermore, we examined whether a highly transcriptionally regulated ERK pathway target, PHLDA1 (TDAG51), suggested to be a tumor suppressor in breast cancer and melanoma, might modulate the transformation process.Cellular transformation of human mammary epithelial cells by downstream Ras signal transduction pathways was examined using anchorage-independent growth assays in the presence and absence of EGFR inhibition. TDAG51 protein expression was down-regulated by interfering small hairpin RNA (shRNA), and the effects on cell proliferation and death were examined in Ras pathway-transformed breast epithelial cells.Activation of both the ERK and PI3K signaling pathways was sufficient to induce cellular transformation, which was accompanied by up-regulation of EGFR ligands, suggesting autocrine EGFR stimulation during the transformation process. Only activation of the ERK pathway was sufficient to transform cells in the presence of EGFR inhibition and was sufficient for tumorigenesis in xenografts. Up-regulation of the PHLDA1 gene product, TDAG51, was found to correlate with persistent ERK activation and anchorage-independent growth in the absence or presence of EGFR inhibition. Knockdown of this putative breast cancer tumor-suppressor gene resulted in increased ERK pathway activation and enhanced matrix-detached cellular proliferation of Ras/Raf transformed cells.Our results suggest that multiple Ras signal transduction pathways contribute to mammary epithelial cell transformation, but that the ERK signaling pathway may be a crucial component downstream of EGFR activation during tumorigenesis. Furthermore, persistent activation of ERK signaling up-regulates TDAG51. This event serves as a negative regulator of both Erk activation as well as matrix-detached cellular proliferation and suggests that TDAG51 opposes ERK-mediated transformation in breast epithelial cells.

SUBMITTER: Oberst MD

PROVIDER: S-EPMC2474852 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

TDAG51 is an ERK signaling target that opposes ERK-mediated HME16C mammary epithelial cell transformation.

Oberst Michael D MD Beberman Stacey J SJ Zhao Liu L Yin Juan Juan JJ Ward Yvona Y Kelly Kathleen K

BMC cancer 20080702

<h4>Introduction</h4>Signaling downstream of Ras is mediated by three major pathways, Raf/ERK, phosphatidylinositol 3 kinase (PI3K), and Ral guanine nucleotide exchange factor (RalGEF). Ras signal transduction pathways play an important role in breast cancer progression, as evidenced by the frequent over-expression of the Ras-activating epidermal growth factor receptors EGFR and ErbB2. Here we investigated which signal transduction pathways downstream of Ras contribute to EGFR-dependent transfor ...[more]

PMID: 18597688

Similar Datasets

Project description:The mammary gland of mammals possesses the specific function of synthesizing, secreting, and delivering milk. Notably, mammary epithelial cells are considered to be central to control the expansion and remodeling of mammary gland into a milk-secretory organ. And the biological function of mammary gland is mainly regulated by the endocrine system, especially for estrogen. G protein-coupled receptor 30 (GPR30), an estrogen membrane receptor, mediates estrogen-induced functions of physiology and pathophysiology. However, the relationship between estrogen/GPR30 signaling and proliferation of goat mammary epithelial cells (gMECs) is still unclear. Herein, estrogen promoted cell proliferation than control, as evidence by upregulation of cell numbers, BrdU-positive cell counts, and cell viability. Of note, these activities were all obviously reduced by treatment with GPR30 antagonist G15, yet GPR30 agonist G1 increased cell proliferation than control. Further, GPR30 silencing inhibited cell proliferation than negative control. This inhibition was accompanied by a G2/M phase arrest and downregulation of cell cycle regulators. Meanwhile, estrogen increased the phosphorylation of ERK1/2 and AKT. Further, the protein level of p-ERK1/2 and p-AKT was enhanced by GPR30 agonist G1 but inhibited by GPR30 antagonist G15 and GPR30 silencing. Importantly, MEK inhibitor and PI3K inhibitor decreased the expression of cell cycle regulators, and repressed estrogen-induced and G1-driven promotion of cell proliferation, suggesting that estrogen regulated cell proliferation of gMECs through mechanisms involving cell cycle, dependent of GPR30 and MEK/ERK and PI3K/AKT signaling pathway. This may provide a strong theoretical basis for researching estrogen sustained-release drugs promoting breast development and improving lactation performance.Abbreviations: gMECs, goat mammary epithelial cells; E2, 17β-estradiol; GPR30, G protein-coupled receptor 30; shRNA, small hairpin RNA; CDK, cyclin-dependent kinase; PI3K, phosphatidylinositol 3-kinase; AKT, proteinkinase B; MAPK, mitogen-activated protein kinase; MEK, mitogen-activated protein kinase kinase; ERK1/2, extracellular signal-regulated kinase 1/2.

Project description:Increasing evidence suggests that repetitive elements may play a role in host gene regulation, particularly through the donation of alternative promoters, enhancers, splice sites, and termination signals. Elevated transcript expression of the endogenous retrovirus group HERV-K (HML-2) is seen in many human cancers, although the identities of the individual proviral loci contributing to this expression as well as their mechanisms of activation have been unclear. Using high-throughput next-generation sequencing techniques optimized for the capture of HML-2 expression, we characterized the HML-2 transcriptome and means of activation in an in vitro model of human mammary epithelial cell transformation. Our analysis showed significant expression originating from 15 HML-2 full-length proviruses, through four modes of transcription. The majority of expression was in the antisense orientation and from proviruses integrated within introns. We found two instances of long terminal repeat (LTR)-driven provirus transcription but no evidence to suggest that these active 5' LTRs were influencing nearby host gene expression. Importantly, LTR-driven transcription was restricted to tumorigenic cells, suggesting that LTR promoter activity is dependent upon the transcriptional environment of a malignant cell.IMPORTANCE Here, we use an in vitro model of human mammary epithelial cell transformation to assess how malignancy-associated shifts in the transcriptional milieu of a cell may impact HML-2 activity. We found 15 proviruses to be significantly expressed through four different mechanisms, with the majority of transcripts being antisense copies of proviruses located within introns. We saw active 5' LTR use in tumorigenic cells only, suggesting that the cellular environment of a cancer cell is a critical component for induction of LTR promoter activity. These findings have implications for future studies investigating HML-2 as a target for immunotherapy or as a biomarker for disease.

Project description:BACKGROUND:Metastasis is the principal cause of renal cell carcinoma-associated mortality. Metadherin (MTDH) was identified as a vital metastasis driver involved in the metastatic progression of various types of tumors, suggesting that MTDH is a prognostic metastatic biomarker and potential therapeutic target. The role and mechanism of MTDH in the metastatic progression of ccRCC have not yet been adequately explored. RESULTS:MTDH was remarkably elevated in ccRCC tissues, especially in metastatic ccRCC tissues, compared with normal kidney tissues and correlated with advanced clinicopathological features and poor prognosis. MTDH activated ERK signaling and EMT, thus promoting the migration and invasion of ccRCC cells. The interaction between MTDH and SND1 at the protein level was confirmed using immunoprecipitation and immunofluorescence. Based on the analysis of datasets from GEO and TCGA, SND1 was remarkably increased in ccRCC, especially in metastatic ccRCC, and associated with advanced clinicopathological features and poor prognosis. Knockdown of SND1 mainly abolished the migration and invasion of ccRCC cells by blocking MTDH-mediated ERK and EMT signaling activation. CONCLUSION:These results revealed that MTDH may be a prognostic metastatic biomarker of ccRCC that promotes ccRCC metastasis by activating SND1-mediated the ERK and EMT signaling pathways. MTDH may serve as an anti-tumor therapeutic target that can be applied for the clinical treatment of metastatic ccRCC. METHODS:MTDH/SND1 mRNA expression in clear cell renal cell carcinoma (ccRCC) was comprehensively estimated by analysis of GEO-ccRCC and TCGA-KIRC datasets with R software and packages. MTDH protein expression was assessed in a total of 111 ccRCC patients from Peking University First Hospital by immunohistochemistry (IHC). In vitro migration and invasion assays were carried out, and an in vivo metastatic mouse model was developed to investigate the biological functions of MTDH in ccRCC cells. Correlation analysis, immunoprecipitation, western blotting and immunofluorescence were applied to explore the molecular mechanisms of MTDH in ccRCC.

Dataset Information

TDAG51 is an ERK signaling target that opposes ERK-mediated HME16C mammary epithelial cell transformation.

Publications

TDAG51 is an ERK signaling target that opposes ERK-mediated HME16C mammary epithelial cell transformation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets