Constitutive activation of mitogen-activated protein (MAP) kinases in human renal cell carcinoma (original) (raw)
Related papers
Cancer Research, 2008
The mitogen-activated protein kinase (MAPK) signaling pathways play essential roles in cell proliferation and differentiation. Recent studies also show the activation of MAPK signaling pathways in tumorigenesis, metastasis, and angiogenesis of multiple human malignancies, including renal cell carcinoma (RCC). To assess the role of this pathway in regulating the proliferation and survival of RCC cells, we first examined the expression of MAPK kinase (MKK) and MAPK in clear cell RCC and confirmed the overexpression of MKK1 and extracellular signal-regulated kinase 2 (ERK2) in these tumors. We then tested the effects of pharmacologic inhibition of MKK on human RCC cell lines, both in vitro and in vivo, using anthrax lethal toxin (LeTx), which cleaves and inactivates several MKKs. Western blotting showed that the phosphorylation levels of ERK, c-Jun-NH 2 kinase, and p38 MAPK decreased after 72 h of LeTx treatment. Exposure to LeTx for 72 h reduced cell proliferation by 20% without significant effects on cell cycle distribution and apoptosis. Anchorageindependent growth of RCC cells was dramatically inhibited by LeTx. In vivo studies showed that tumor growth of RCC xenografts could be suppressed by LeTx. Extensive necrosis and decreased tumor neovascularization were observed after LeTx treatment. LeTx also showed direct inhibition of proliferation of endothelial cells in vitro. Our results suggest that suppression of one or more MAPK signaling pathways may inhibit RCC growth through the disruption of tumor vasculature. [Cancer Res 2008;68(1):81-8]
MAPK SIGNALLING PATHWAY: ROLE IN CANCER PATHOGENESIS
Cancer is one of the prime causes of death presently. In normal cells, the firmly regulated pathway relays extracellular signals from the cell membrane to nucleus through a cascade of phosphorylation events. The Mitogen-Activated Protein Kinase (MAPK) cascades are among the most thoroughly studied signal transduction systems and have been proven to participate in a diverse array of cellular programs consisting of cell differentiation, cell movement, cell division and cell death. Constitutive activation of the MAPK cascade is associated with the carcinogenesis and melanoma development because of activating mutations within the B-RAF and RAS genes or other genetic or epigenetic modifications in their components or upstream activation of cell-surface receptors (e. g., EGFR and Flt-3) and chimeric chromosomal translocations (e. g. BCR-ABL) leading to elevated signaling activity eliciting cellular proliferation, invasion, metastasis, migration, survival and angiogenesis. Even in the absence of apparent genetic mutations, MAPK pathway has been stated to be activated in over 50% of Acute Myelogenous Leukemia (AML) and acute lymphocytic leukemia. In this brief review, we are about to outline the current advances in understanding the regulation of Mitogen-activated protein kinase signaling system and how can we generate specificity.
Role of MAP kinase in tumor progression and invasion : Protein kinases
Cancer Metastasis Reviews, 2003
Activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway is a frequent event in tumorigenesis. MAPKs have been implicated in cell migration, proteinaseinduction, regulation of apoptosis, and angiogenesis, events that are essential for successful completion of metastasis. In this review, we discuss the potential role that MAPKs play in metastasis by regulating cell migration, proteinase-induction and apoptosis.
Role of MAP kinase in tumor progression and invasion
Cancer metastasis reviews, 2003
Activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway is a frequent event in tumorigenesis. MAPKs have been implicated in cell migration, proteinase-induction, regulation of apoptosis, and angiogenesis, events that are essential for successful completion of metastasis. In this review, we discuss the potential role that MAPKs play in metastasis by regulating cell migration, proteinase-induction and apoptosis.
Activities of MAP-Kinase Pathways in Normal Uroepithelial Cells and Urothelial Carcinoma Cell Lines
Experimental Cell Research, 2003
It is often assumed that MAPK pathways drive proliferation of normal uroepithelial (UEC) and urothelial carcinoma (TCC) cells. To check this assumption, activities and inducibilities of promoters containing serum-response elements (SRE) or AP-1 binding sites were investigated in cultured UEC and seven TCC lines. Reporter plasmids dependent on SRE or AP-1 sites were highly active in UEC, but significantly less so in TCC lines. Reporter activity in TCC lines could be induced by constitutively active MEKK4 or TPA. Accordingly, phosphorylation of the MAPK pathway components MEK, ERK, and ELK1 was most pronounced in UEC and lower in TCC lines. MAPK-dependent promoter activities and bromodeoxyuridine incorporation decreased in UEC upon withdrawal of growth factors, but less so in TCC lines, in which serum diminution increased apoptosis. Likewise, E2Fdependent promoters responded to growth factors in UEC, but were more serum-independent in the TCC lines, which lack either RB1 or p16 INK4A . MEK inhibitors inhibited BrdU incorporation in UEC more strongly than in TCC lines. Thus, proliferation of normal uroepithelial cells is indeed associated with activation of MAPK pathways. However, autonomous proliferation of TCC lines-unexpectedly-appears much less dependent on MAPK activation and may rather be promoted by defects in cell cycle regulation.
A Comprehensive Review on MAPK: A Promising Therapeutic Target in Cancer
Cancers, 2019
The mitogen-activated protein kinase (MAPK) pathway is an important bridge in the switch from extracellular signals to intracellular responses. Alterations of signaling cascades are found in various diseases, including cancer, as a result of genetic and epigenetic changes. Numerous studies focused on both the homeostatic and the pathologic conduct of MAPK signaling; however, there is still much to be deciphered in terms of regulation and action models in both preclinical and clinical research. MAPK has implications in the response to cancer therapy, particularly the activation of the compensatory pathways in response to experimental MAPK inhibition. The present paper discusses new insights into MAPK as a complex cell signaling pathway with roles in the sustenance of cellular normal conduit, response to cancer therapy, and activation of compensatory pathways. Unfortunately, most MAPK inhibitors trigger resistance due to the activation of compensatory feed-back loops in tumor cells an...
Tpl-2 acts in concert with Ras and Raf-1 to activate mitogen-activated protein kinase
Proceedings of the National Academy of Sciences, 1994
Mitogenic signals initiated at the plasma membrane by extracellular factors acting on receptor tyrosine kinass or G protein-coupled receptors are transmitted to the nucleus through an intricate signaling network. Components of this network participate, upon stimulation, in a complex array of phosphorylation-dependent protein-protein interactions which leads to the formation of transient multimolecular complexes. Complexes containing products of the protooncogenes ras and raf-4 and the protein kinase MEK-1 activate the mitogen-activated protein kinases (MAPKs), which play a central role in the integration of different mitogenic signals by directly phosphorylating cytoplasmic and nuclear targets. In this report we present evidence that the kinase encoded by the tumor progression locus 2 gene (Tpl-2) contributes to the activation of the MAPK cascade. MAPK activation induced by the Tpl-2 protein is blocked by dominant negative mutants of Ras and Raf-i, whereas a kinase-deficient Tpl-2 mutant downregulates mitogenic signals induced by v-Ha-Ras or v-Raf. These data suggest that Tpl-2 activates the MAPK cascade, perhaps through its participation in the assembly of Ras/Raf-1-containing multimolecular complexes. The family of mitogen-activated protein kinases (MAPKs, also known as extracellular signal-regulated kinases, ERKs) plays a central role in the regulation of cell proliferation (1, 2). MAPK activity is regulated by phosphorylation on tyrosine and threonine residues (3-5) which is mediated by MAPK/ERK kinase 1 (MEK-1) (6-12). The latter, in turn, is activated by at least two converging mitogenic signaling pathways. One of these pathways integrates signals generated by activated receptor tyrosine kinases and protein kinase C. This pathway leads to the activation of the protein kinase Raf-1 (13-18), which phosphorylates MEK-1. The activation of Raf-1 appears to depend on the translocation of Raf-1 to the plasma membrane (19), which may be due, at least in part, to the direct association of Raf-1 with Ras from the American Type Culture Collection (ATCC)], Raf-1S621A (kindly provided by D. Morrison, Frederick Cancer Research Facility, Frederick, MD), and v-Raf, were prepared by inserting the corresponding cDNAs into the polylinker of the vector pCMV-5. Cell Lines and Cel Transfections. COS-1 monkey kidney cells were obtained from ATCC and NIH 3T3 mouse fibroblasts were kindly provided by J. Freed (Fox Chase Cancer Center). The cells were maintained in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10%6 fetal bovine serum (COS-1) or 10% bovine calf serum (NIH 3T3), pencillin (50 units/ml), streptomycin (50 pg/ml), and kanamycin (100 Hg/ml). COS-1 cells were transiently transfected with various mammalian expression constructs by the DEAE-dextran/ chloroquine method (41). Briefly, 24 hr prior to transfection Abbreviations: MAPK/ERK, mitogen-activated/extracellular signal-regulated protein kinase; MEK-1, MAPK/ERK kinase 1; MEK-K, MEK kinase; EGF, epidermal growth factor; PMA, phorbol 12-myristate 13-acetate; MBP, myelin basic protein. *To whom reprint requests should be addressed.
Cytosolic and Nuclear Mitogen-Activated Protein Kinases Are Regulated by Distinct Mechanisms
Experimental Cell Research, 1996
ERKs) belong to a group of protein serine/threonine We have investigated the regulation and localization kinases [8]. The most widely studied MAPKs, the of mitogen-activated protein kinase (MAPK) and mito-ubiquitously expressed p42 and p44 MAPK isoforms, gen-activated protein kinase kinase (MAPKK) in both are rapidly phosphorylated and activated in response cytosolic and nuclear fractions of glomerular mesanto stimulation of a wide array of membrane-associated gial cells. p42 MAPK was localized by both immunoblot signaling molecules, including receptor tyrosine kiand kinase activity in both cytosol and nucleus and nases [1-8], protein kinase C (PKC) [9], G-proteins, was rapidly activated, in both fractions, by fetal boand Ras [12][13]. A variety of cellular components have vine serum and TPA. Downregulation of protein kibeen shown to be MAPK substrates, including EGF nase C (PKC) by TPA inhibited stimulation of cytosolic receptor [14], phospholipase A2 16], Rsk 90 [17], p42 MAPK, but unexpectedly had no effect on stimujun, and fos 19]. Therefore, MAPKs appear to be lated p42 MAPK in the nucleus. Next we studied the transducers integrating multiple intracellular signals. upstream kinase p45 MAPKK by indirect immunoflu-p42 and p44 MAPKs localize in both cytoplasm and orescence microscopy, Western blot analysis, and kinucleus in G0-arrested cells [20-23]. They become actinase specific activity. Unlike MAPK, p45 MAPKK is alvated after growth factor stimulation and the cytomost exclusively cytosolic in resting cells and kinase plasmic MAPKs translocate into the nucleus, thereby activity stimulated by TPA is restricted to the cytosol. transmitting the extracellular signals into the nucleus Interestingly, PKC downregulation for 24 h with TPA [5, 20-23]. However, several lines of experimental redramatically enhanced nuclear MAPKK as assessed by sults are not entirely consistent with this theory. First, all three techniques. Cytosolic stimulated MAPKK was the translocation occurs at 5 min and reaches a maxiattenuated in PKC downregulation. Collectively these mum 3 to 4 h after stimulation [20, 23], whereas the results show that in mesangial cells: (i) p42 MAPK and maximal MAPK activity is generally found at 5 min p45 MAPKK localize in both the cytosol and the nufollowed by a rapid decline due to dephosphorylation cleus, and (ii) PKC exerts a negative effect on nuclear MAPKK activity as documented by PKC downregula-of the kinases [1 -8]. Second, the translocation of tion, which augments p45 MAPKK nuclear mass and MAPKs can proceed with kinase-deficient mutants activity. These results indicate that the dual regula- [22]. Third, no lag period between the activation of nution of these two kinases is under differential control clear MAPKs and that of cytosolic MAPKs is found and in the cytosol and the nucleus. ᭧ 1996 Academic Press, Inc.
Journal of Hepatology, 1999
Background/Aims: The ras-mitogen-activated protein kinase (MAPK) cascade plays an important role not only in the mitogenic signal transduction pathway but also in the development of cancer, and it is believed to be one of the important regulators in normal hepatocytes and hepatocellular carcinoma. The aim of this study was to determine the role of insulin receptor substrate-l and the MAPK cascade in rats with hepatocellular carcinoma induced by 3'-methyl-4-dimethylamino-azobenzene (3'-MeDAB). Methods: Liver cancer was induced in rats by feeding 3'-MeDAB, and the changes in expression of IRS-l and MAPK were analyzed in tumorous, non-tumorous and control liver. Results: Expression of insulin receptor substrate-l (IRS-l) showed a 1.4fold increase at protein level in T UMORS SHOW abnormalities in growth factors and their receptors, inducing epidermal growth factor (EGF) and v-erbB (l), heparin-binding growth factor (HBG) and K-Sam, or hepatocyte growth factor (HGF) and c-met, which can result from gene amplification and lead to overexpression of normal RNAs and proteins (2-5). In glioma cells, for example, amplification of the EGF receptor is associated with increased receptor kinase activity (5). These studies indicate that growth factors and their receptors may play an important role in tumor growth in malignancy and