Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NEU (ERBB2) and other members of the epidermal growth factor receptor (EGFR) family have been implicated in human prostate cancer (CAP) development and progression to an androgen-independent state, but the extent of involvement and precise role of this signaling pathway remain unclear. To begin addressing such open questions in an animal model, we have developed a transgenic line in which an oncogenic Neu cDNA (Neu*) driven by the probasin gene promoter is overexpressed in the mouse prostate and causes development of prostatic intraepithelial neoplasia (PIN) that progresses to invasive carcinoma. Expression profiling using microarrays, which was selectively validated and extended by immunophenotyping of Neu*-induced PIN and CAP, led to the identification of some novel biomarkers and also revealed increased expression of Egfr, Erbb3 and phosphorylated androgen receptor. In view of this information from our mouse model, which can be used to analyze further the role of Erbb signaling in prostatic tumorigenesis, we examined human prostate cancer tissue arrays by immunohistochemistry. Based on statistical analyses of the results, we propose the testable hypothesis that ERBB3, shown to be expressed in 86% of the human CAP cases that we examined, is the pivotal element of the Erbb pathway promoting tumorigenesis by heterodimerization with NEU or EGFR, while a NEU/EGFR dimer does not appear to play a significant role in CAP.
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PMID:Prostatic intraepithelial neoplasia and adenocarcinoma in mice expressing a probasin-Neu oncogenic transgene. 1640 39

Androgens such as dihydrotestosterone (DHT) are known to exert their effects through the activation of intracellular receptors that regulate the transcription of target genes. Alternatively, nongenomic mechanisms, including the activation of such signaling pathways as the MAPK pathways, have been described. It is unclear, however, whether this latter mechanism of action is mediated by the classical androgen receptor (AR) or some alternative mechanism. In this study, using a glial cell model (C6 cells) that we found to express the AR, we identified that DHT increased the phosphorylation of both ERK and Akt, key effectors of the neuroprotection-associated MAPK and phosphoinositide 3-kinase signaling pathways, respectively, and ERK phosphorylation was blocked by the AR antagonist, flutamide. In contrast, the membrane-impermeable, BSA-conjugated androgen (DHT-BSA) caused a dose-dependent suppression of ERK and Akt phosphorylation, suggesting the existence of a novel membrane-associated AR that mediates this opposite effect on neuroprotective signaling. This is also supported by the observation of DHT-displaceable binding sites on the cell surface of live C6 cells. Collectively, these data support the existence of a novel membrane-associated AR in glial cells and argue for the existence of two, potentially competing, pathways in a given cell or tissue. This mutual antagonism was supported by the ability of DHT-BSA to attenuate DHT-induced ERK phosphorylation. Thus, depending on the predominance of one receptor mechanism over another, the outcome of androgen treatment may be very different and, as such, could help explain existing discrepancies as to whether androgens are protective or damage inducing.
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PMID:Dihydrotestosterone differentially modulates the mitogen-activated protein kinase and the phosphoinositide 3-kinase/Akt pathways through the nuclear and novel membrane androgen receptor in C6 cells. 1641 Feb 99

Prostate epithelial stem cells are self-renewing cells capable of differentiation into prostate epithelium, and are thought to contribute towards both benign and malignant conditions in the human prostate. We have previously demonstrated that prostate epithelial basal cells express high levels of integrin alpha2beta1 and this population can be subdivided into stem (alpha2beta1(hi) CD133+) and transient-amplifying population (TAP) cells (alpha2beta1(hi) CD133-). However, the molecular mechanism(s) controlling the commitment and regulation of these cells towards differentiated epithelium remains unclear. Here, we demonstrate that beta1 integrin function is required for the maintenance of basal prostatic epithelial cells and suppression of its function by either methylcellulose or, more specifically, beta1-blocking antibody (80 microg/ml) induces differentiation, with associated expression of the differentiation-specific markers prostate acid phosphatase (PAP) and cytokeratin 18 (CK18). Keratinocyte growth factor (KGF), a stromal-derived growth factor, has previously been implicated in prostate organogenesis using in vitro tissue recombination experiments. We show that treatment with KGF (10 ng/ml) potently induces epithelial differentiation with concomitant suppression of alpha2beta1 integrin expression as well as the induction of androgen receptor expression. Specifically, p38-MAPK appears to be involved and the presence of SB202190, a p38 inhibitor, significantly blocks KGF-induced differentiation. Furthermore, the expression of the high-affinity receptor tyrosine kinase to KGF (FGFR2) is predominantly detectable in alpha2beta1(hi) CD133- TAP cells when compared with stem cells (alpha2beta1(hi) CD133+), which would therefore be relatively unresponsive to the differentiating effect of KGF. Taken together, using a human primary culture model, we have demonstrated key roles for interactions between KGF and integrin-mediated function in the regulation of prostate epithelial differentiation.
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PMID:KGF suppresses alpha2beta1 integrin function and promotes differentiation of the transient amplifying population in human prostatic epithelium. 1655 39

Endocrine therapy for advanced prostate cancer is based on androgen ablation or blockade of the androgen receptor (AR). AR action in prostate cancer has been investigated in a number of cell lines, their derivatives, and transgenic animals. AR expression is heterogenous in prostate cancer in vivo; it could be detected in most primary tumors and their metastases. However, some cells lack the AR because of epigenetic changes in the gene promoter. AR expression increases after chronic androgen ablation in vitro. In several xenografts, AR upregulation is the most consistent change identified during progression towards therapy resistance. In contrast, the AR pathway may be by-passed during chronic treatment with a nonsteroidal anti-androgen. AR sensitivity in prostate cancer increases as a result of activation of the Ras/mitogen-activated protein kinase pathway. One of the major difficulties in endocrine therapy for prostate cancer is acquisition of agonistic properties of AR antagonists observed in the presence of mutated AR. Enhancement of AR function by associated coactivator proteins has been extensively investigated. Cofactors SRC-1, RAC3, p300/CBP, TIF-2, and Tip60 are upregulated in advanced prostate cancer. Most studies on ligand-independent activation of the AR are focused on Her-2/neu and interleukin-6 (IL-6). On the basis of studies that showed overexpression and activation of the AR in advanced prostate cancer, it was suggested that novel therapies that reduce AR expression will provide a benefit to patients. There is experimental evidence showing that prostate tumor growth in vitro and in vivo is inhibited following administration of chemopreventive drugs or antisense oligonucleotides that downregulate AR mRNA and protein expression.
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PMID:Androgen axis in prostate cancer. 1659 69

Huggins and Hodges described the first systemic targeted therapy for prostate cancer in 1941 with their report on the effects of androgen ablation in men with metastatic disease. Since that time, researchers have identified multiple additional "targets" that may be important in prostate cancer tumorigenesis. These areas include continued emphasis on the androgen receptor in the androgen-independent state, parallel growth pathways such as AKT and HER2 that may act in conjunction or independently of the androgen receptor, the supporting environment that allows for the development of metastatic disease, and standard cytotoxic targets, such as the microtubule. This review is intended to highlight these potential targets and several of the agents that are under development in the treatment of prostate cancer.
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PMID:Targeted approaches for the management of metastatic prostate cancer. 1661 85

Extracellular signal-regulated kinase 8 (ERK8) is the most recently identified member of the ERK subfamily of MAPKs. Although other members of the ERK subfamily are established regulators of signaling pathways involved in cell growth and/or differentiation, less is known about ERK8. To understand the cellular function of ERK8, a yeast two-hybrid screen of a human lung library was performed to identify binding partners. One binding partner identified was Hic-5 (also known as ARA55), a multiple LIM domain containing protein implicated in focal adhesion signaling and the regulation of specific nuclear receptors, including the androgen receptor and the glucocorticoid receptor (GR). Co-immunoprecipitation experiments in mammalian cells confirmed the interaction between Hic-5 and both ERK8 and its rodent ortholog ERK7. The C-terminal region of ERK8 was not required for the interaction. Although the LIM3 and LIM4 domains of Hic-5 were sufficient and required for this interaction, the specific zinc finger motifs in these domains were not. Transcriptional activation reporter assays revealed that ERK8 can negatively regulate transcriptional co-activation of androgen receptor and GRalpha by Hic-5 in a kinase-independent manner. Knockdown of endogenous ERK8 in human airway epithelial cells enhanced dexamethasone-stimulated transcriptional activity of endogenous GR. Transcriptional regulation of GRalpha and interaction with its ligand binding domain by ERK8 were dependent on the presence of Hic-5. These results provide the first physiological function for human ERK8 as a negative regulator of human GRalpha, acting through Hic-5, and suggest a broader role for ERK8 in the regulation of nuclear receptors beyond estrogen receptor alpha.
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PMID:ERK8 down-regulates transactivation of the glucocorticoid receptor through Hic-5. 1662 5

Prevention trials showed that selenium reduced prostate cancer incidence by 50%, establishing selenium as a promising chemopreventive agent for prostate cancer. Selenium inhibited human prostate cancer cell growth, blocked cell cycle progression at multiple transition points, and induced apoptotic cell death. Previous studies showed a novel mechanism of selenium anticancer action in which selenium markedly reduces androgen signaling and androgen receptor (AR)-mediated gene expression, including prostate-specific antigen (PSA), in human prostate cancer cells. The molecular mechanisms of selenium-mediated down-regulation of AR signaling are not clear. In this study, a systemic approach was taken to examine the modification of androgen signaling by selenium in human prostate cancer cells. In addition to reduced AR mRNA expression, selenium was found to initially increase the stability of AR mRNA within 6 hours while decreasing the stability of AR mRNA after 8 hours. Selenium increased AR protein degradation and reduced AR nuclear localization. Scatchard analysis indicated that selenium did not affect ligand binding to AR in LNCaP cells. Chromatin immunoprecipitation analyses showed that DHT increased the recruitment of AR and coactivators, such as SRC-1 and TIF-2, to the promoter of the PSA gene, and that recruitment was greatly diminished in the presence of 5 micromol/L selenium. On the other hand, selenium enhanced the recruitment of corepressors, such as SMRT, to the promoter of the PSA gene. Taken together, these results suggest that selenium disrupts AR signaling at multiple stages, including AR mRNA expression, mRNA stability, protein degradation, nuclear translocation, and recruitment of coregulators.
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PMID:Mechanisms of selenium down-regulation of androgen receptor signaling in prostate cancer. 1664 61

In normal prostate, keratinocyte growth factor (KGF), also known as fibroblast growth factor-7 (FGF-7) serves as a paracrine growth factor synthesized in stromal cells that acts on epithelial cells through its receptor, KGFR. KGF and KGFR were found in human cancer epithelial cells as well as stromal cells. Since KGF expressed in epithelial cells of benign prostatic hyperplasia (BPH) and in prostate cancer, it has been suggested that KGF might act as an autocrine factor in BPH and prostate cancer. To investigate the roles of KGF in cancerous stroma, primary cultured human prostate cancer stromal cells (PCSCs) were isolated and evaluated. These PCSCs possessed estrogen receptors and KGFR, but not androgen receptor as determined by RT-PCR and Western blot, respectively. KGF exhibited mitogenic and anti-apoptotic effects that correlated with induction of cyclin-D1, Bcl-2, Bcl-xL and phospho-Akt expression in PCSCs, where treatment with KGF antiserum abolished cell proliferation and anti-apoptotic protein expression. PCSCs exposed to KGF for various time periods resulted in phosphorylation of Akt and subsequent up-regulation of Bcl-2. KGF modulated dynamic protein expression indicated that KGF triggered cell cycle machinery and then activated anti-apoptotic actions in PCSCs. Cell proliferation analysis indicated that tamoxifen or ICI 182,780 reduced cell viability in a dose-dependent manner; however, KGF prevented this inhibition, which further demonstrated KGF triggered anti-apoptotic machinery through activating Bcl-2 and phospho-Akt expression. In summary, KGF has an autocrine effect and serves as a survival factor in primary cultured human prostate cancer stromal cells.
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PMID:Effect of keratinocyte growth factor on cell viability in primary cultured human prostate cancer stromal cells. 1685 82

Sebaceous differentiation has been described in only limited examples of benign and malignant epithelial lesions of the breast. We report a rare case of mammary sebaceous carcinoma to further delineate its morphologic features. Microscopically, the tumor, arising in the right mammary gland of a 63-year-old woman, was composed of well-defined solid sheets or lobules of atypical epithelial cells including many large pale or clear cells with often scalloped nuclei and coarsely vacuolated cytoplasm, in which abundant lipid droplets were identified with oil-red-O staining. Immunohistochemical expressions of cytokeratin, epithelial membrane antigen, and receptors of estrogen and progesterone were detected, whereas GCDFP-15, S-100 protein, vimentin, alpha-smooth muscle actin, p63, androgen receptor, and the HER2/neu protein were not expressed. Besides, a subset of the tumor cells co-expressed synaptophysin, neurofilament, and PGP9.5, suggesting neuroendocrine differentiation that is a hitherto undescribed phenomenon in the mammary tumors with sebaceous features. This case would expand the morphologic diversity of carcinoma of the breast.
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PMID:Sebaceous carcinoma of the breast: case report and review of the literature. 1694 38

AR (androgen receptor) and PSA (prostate-specific antigen) are involved in the pathogenesis of breast cancer, but their role is not clearly defined. The purpose of this study was to analyze by immunohistochemistry the AR and PSA (prostate-specific antigen) expression in 156 female breast carcinomas and to correlate the results with some histopathological parameters, like ER (estrogen receptor), PR (progesterone receptor), HER2/neu, nodal and metastasis status, histological type and grade. ARs and PSA were expressed in 112/156 (72%) and respectively in 61/156 (39%) of cases and we found a positive correlation between AR and PSA expression in breast carcinomas (p<0.0002). We also found an association between the histological type of the tumor and AR (p<0.001), respectively PSA (p=0.01) and between AR and the grade of differentiation (p=0.007) and the nodal status (p=0.02). No correlations were found between the metastasis status and AR or PSA. 47.3% (53/112) of AR-positive cases and 46% (28/61) of PSA-positive cases were ER-negative. High frequency of AR (87.5%) and PSA (75%) expression was found in medullary carcinomas and 53% of lobular invasive carcinomas co-expressed AR and PSA. We found an inverse correlation between HER2/neu and PSA (p=0.05). Although most of the PSA-positive carcinomas were lymph node-negative, well and moderately differentiated, we did not find any statistically significant correlations between these parameters and PSA expression. Our study confirms that ARs are commonly expressed in breast cancer and the expression of PSA and AR are highly correlated. Moreover, all the lobular carcinomas and the majority of medullary carcinomas co-expressed AR and PSA, the majority of AR-positive carcinomas were lymph node-negative, well and moderately differentiated, and large number of ER-negative carcinomas expressed AR and PSA.
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PMID:Immunohistochemical expression of androgen receptor and prostate-specific antigen in breast cancer. 1697 95


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