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)

The sequence-tagged site (STS) D10S170, also referred to as H4, is a gene of unknown function. Its 5' end was found fused to the catalytic domain of the RET protooncogene to generate RET/PTC 1, the most common form of PTC oncogenes in human papillary thyroid carcinoma. This gene has previously been assigned to a very large genomic region, 10q11.22-->q22.1. Here, we describe the application of a novel hybridization scheme to the physical and genetic mapping of D10S170. First, we selected a homologous large-insert DNA clone from a human P1 library by filter hybridization and confirmed its authenticity by Southern blot analysis. Triple-color fluorescence in situ hybridization (FISH) experiments mapped this clone to l0q21.2-->q21.3. "Binning" experiments were performed using a quadruple-color FISH approach aimed toward placing the gene in a genetic interval defined by differentially labeled P1 DNA probes containing known polymorphic markers. We found that multicolor FISH greatly expedites chromosomal mapping. Finally, we applied our FISH approach to determine the extent of deletion involving this locus (D10S170) in a papillary thyroid cancer cell line, TPC-1.
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PMID:A novel multicolor hybridization scheme applied to localization of a transcribed sequence (D10S170/H4) and deletion mapping in the thyroid cancer cell line TPC-1. 906 36

Among oncogenes studied in thyroid cancers, a specific activated form of c-ret has been found in a minority of papillary thyroid carcinomas (PTCs). In these tumours, c-ret is activated when by somatic rearrangements, the intracellular domain of RET is juxtaposed with the amino-terminal portion of a different donor gene such as H4, thereby generating a chimeric transcript (ret/PTC-1). The functional effects of c-ret activation and its prognostic implications are currently unclear. This study was undertaken to assess the frequency of RET/PTC-1 expression, any distinctive features of positive tumours to which it might be related, and its prognostic importance. Archival material from 88 thyroid neoplasms [50 PTCs, eight anaplastic carcinomas (ATCs), 25 follicular thyroid carcinomas (FTCs) and five follicular adenomas (FAs)] were analysed for ret/PTC-1 and H4 expression using 5' nuclease assay (TaqMan RT-PCR). RNA from the TPC-1 cell line was included as a positive control for c-ret activation. No FTC or FA displayed activation of ret/PTC-1, though all expressed H4. c-ret activation was found in 24% of PTCs (12 of 50), in 87.5% of ATCs (7 of 8), and in 33% of the combined PTC/ATC group. The frequency of c-ret activation in the aggressive ATC variants noted here suggests that ret/PTC-1-positive PTCs might also have a similar poor prognosis and a follow-up study on this cohort is in progress. Ninety per cent of ret/PTC-1-positive tumours failed to express H4, a phenomenon that has not been described previously and which may have considerable bearing on tumour morphology. A statistically significant proportion (58%) of ret/PTC-1-positive, H4-negative PTCs was associated with chronic inflammatory cell infiltration of the tumour and/or the surrounding thyroid. This association has not been reported previously.
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PMID:Assessment of ret/PTC-1 rearrangements in neoplastic thyroid tissue using TaqMan RT-PCR. 1095 97

Rearrangement of RET proto-oncogene is the major event in the etiopathogenesis of papillary thyroid carcinoma (PTC). We report a high prevalence of BRAF(V599E) mutation in sporadic PTC and in PTC-derived cell lines. The BRAF(V599E) mutation was detected in 23 of 50 PTC (46%) and in three of four PTC-derived cell lines. The prevalence of the BRAF(V599E) mutation in PTC is the highest reported to date in human carcinomas, being only exceeded by melanoma. PTC with RET/PTC rearrangement as well as the TPC-1 cell line (the only one harboring RET/PTC rearrangement) did not show the BRAF(V599E) mutation. BRAF(V599E) mutation was not detected in any of 23 nodular goiters, 51 follicular adenomas and 18 follicular carcinomas. A distinct mutation in BRAF (codon K600E) was detected in a follicular adenoma. Activating mutations in RAS genes were detected in 15% of FA, 33% of FTC and 7% of PTC. BRAF(V599E) mutation did not coexist with alterations in any of the RAS genes in any of the tumors. These results suggest that BRAF(V599E) mutation is frequent in the etiopathogenesis of PTC. The BRAF(V599E) mutation appears to be an alternative event to RET/PTC rearrangement rather than to RAS mutations, which are rare in PTC. BRAF(V599E) may represent an alternative pathway to oncogenic MAPK activation in PTCs without RET/PTC activation.
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PMID:BRAF mutations and RET/PTC rearrangements are alternative events in the etiopathogenesis of PTC. 1288 14

Genetic alterations causing oncogenic activation of the RET gene are recognized as pathogenic events in papillary and medullary thyroid carcinomas. Inhibition of Ret oncoprotein functions could thereby represent a specific therapeutic approach. We previously described the inhibitory activity of the 2-indolinone derivative RPI-1 (formerly Cpdl) on the tyrosine kinase activity and transforming ability of the products of the RET/PTC1 oncogene exogenously expressed in murine cells. In the present study, we investigated the effects of RPI-1 in the human papillary thyroid carcinoma cell line TPC-1 spontaneously harboring the RET/PTC1 rearrangement. Treatment with RPI-1 inhibited cell proliferation and induced accumulation of cells at the G2 cell cycle phase. In treated cells, Ret/Ptc1 tyrosine phosphorylation was abolished along with its binding to Shc and phospholipase C(gamma), thereby indicating abrogation of constitutive signaling mediated by the oncoprotein. Activation of JNK2 and AKT was abolished, thus supporting the drug inhibitory efficacy on downstream pathways. In addition, cell growth inhibition was associated with a reduction in telomerase activity by nearly 85%. These findings in a cellular context relevant to the pathological function of RET oncogenes support the role of Ret oncoproteins as useful targets for therapeutic intervention, and suggest RPI-1 as a promising candidate for preclinical development in the treatment of thyroid tumors expressing RET oncogenes.
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PMID:Inactivation of Ret/Ptc1 oncoprotein and inhibition of papillary thyroid carcinoma cell proliferation by indolinone RPI-1. 1294 31

Ret oncoproteins expressed in thyroid carcinomas represent possible targets for therapeutic intervention. Oncogenic activation of the receptor tyrosine kinase encoding RET gene occurs typically by gene rearrangement in papillary thyroid carcinomas (PTC) and by missense mutation in medullary thyroid carcinomas (MTC). These genetic alterations lead to the expression of deregulated products characterized by ligand-independent activation of the intrinsic tyrosine kinase of Ret. Such features suggest the possibility of using specific tyrosine kinase inhibitors to block the Ret oncoproteins signaling. The present report summarizes the cellular effects of the arylidene 2-indolinone Ret inhibitor RPI-1 (formerly Cpd1) on the human PTC cell line TPC-1 which spontaneously harbors the RET/PTC1 oncogene. The results provide evidence that RPI-1 is able to inhibit cell growth and to interfere with Ret/ptc1-driven signaling. These findings support a role for Ret oncoproteins as therapeutic targets and the pharmacological interest of RPI-1 as a candidate drug for preclinical evaluation on thyroid tumors expressing RET oncogenes.
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PMID:RET/PTC oncoproteins: molecular targets of new drugs. 1487 Jul 76

Destruction of the neovasculature is essential for efficient tumor eradication by photodynamic therapy (PDT). Since the over-expression of receptors for vascular endothelial growth factor (VEGF) is correlated with tumor angiogenesis and subsequent growth, we conjugated a photosensitizer (5-(4-carboxyphenyl)-10,15,20-triphenyl-chlorin, TPC), via a spacer (6-aminohexanoic acid, Ahx), to a VEGF receptor-specific heptapeptide (ATWLPPR). ATWLPPR and TPC-Ahx-ATWLPPR bound exclusively to neuropilin-1 (NRP-1) recombinant chimeric protein (IC50=19 and 171 microM, respectively) but were devoid of affinity for VEGF receptor type 2 (VEGFR-2, KDR), to which ATWLPPR was initially thought to bind. TPC-Ahx-ATWLPPR was incorporated up to 25-fold more in human umbilical vein endothelial cells (HUVEC) than TPC over a 24-h period, and the addition of 8 mM ATWLPPR induced a significant decrease of this uptake (P<0.05), corroborating a receptor-mediated incorporation. Slightly less cytotoxic in the dark, TPC-Ahx-ATWLPPR exhibited enhanced in vitro photodynamic activity (10.4-fold), compared to TPC. Pharmacokinetic analysis in nude mice xenografted with U87 human malignant glioma cells revealed relevant tumor levels as soon as 1 h after intravenous injection of TPC-Ahx-ATWLPPR, and a rapid elimination from the blood compartment. Moreover, TPC-Ahx-ATWLPPR was not degraded in vivo up to 2 h after intravenous injection. Taken together, our results demonstrate that TPC-Ahx-ATWLPPR is a much more potent photosensitizer in vitro than TPC, in NRP-1-expressing cells. Thus, it may efficiently potentiate the vascular effect of PDT in vivo.
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PMID:A peptide competing with VEGF165 binding on neuropilin-1 mediates targeting of a chlorin-type photosensitizer and potentiates its photodynamic activity in human endothelial cells. 1642 22

At least 15 different translocations have been described activating RET in papillary thyroid carcinomas. A break-apart fluorescence in situ hybridization (FISH) assay should detect many translocations involving the RET gene without requiring knowledge of the partner gene. G-banding and spectral karyotyping was performed to further characterize the papillary carcinoma cell line TPC-1. BAC clones flanking the 5' and 3' regions of RET were labeled with SpectrumRed and biotin detected with avidin-AMCA (blue). In addition to the previously described chromosomal t(1;10;21), TPC-1 was found to have del(7)(q22q31) and der(8)t(8;8)(p21;q11.2). With the BAC probes, TPC-1 interphase nuclei showed the expected signal pattern of one paired red-blue signal as well as separated red and blue signals from the rearranged RET gene in 93% of cells. Interphase nuclei from normal human lymphocytes showed two paired red-blue signals in 97% of cells. TPC-1 cells were found to have the previously described chromosomal rearrangement that involves chromosome 10, with few other cytogenetically detectable genomic alterations. RET rearrangement can be detected by a break-apart BAC FISH probe set in the interphase nuclei of TPC-1 cells. This assay can potentially detect clinically relevant translocations involving RET.
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PMID:A break-apart fluorescence in situ hybridization assay for detecting RET translocations in papillary thyroid carcinoma. 1795 68

How cyclic AMP (cAMP) could positively or negatively regulate G1 phase progression in different cell types or in cancer cells versus normal differentiated counterparts has remained an intriguing question for decades. At variance with the cAMP-dependent mitogenesis of normal thyroid epithelial cells, we show here that cAMP and cAMP-dependent protein kinase activation inhibit S-phase entry in four thyroid carcinoma cell lines that harbor a permanent activation of the Raf/ERK pathway by different oncogenes. Only in Ret/PTC1-positive TPC-1 cells did cAMP markedly inhibit the Raf/ERK cascade, leading to mTOR pathway inhibition, repression of cyclin D1 and p21 and p27 accumulation. p27 knockdown did not prevent the DNA synthesis inhibition. In the other cells, cAMP little affected these signaling cascades and levels of cyclins D or CDK inhibitors. However, cAMP differentially inhibited the pRb-kinase activity and T172-phosphorylation of CDK4 complexed to cyclin D1 or cyclin D3, whereas CDK-activating kinase activity remained unaffected. At variance with current conceptions, our studies in thyroid carcinoma cell lines and previously in normal thyrocytes identify the activating phosphorylation of CDK4 as a common target of opposite cell cycle regulations by cAMP, irrespective of its impact on classical mitogenic signaling cascades and expression of CDK4 regulatory partners.
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PMID:Cyclic AMP inhibits the proliferation of thyroid carcinoma cell lines through regulation of CDK4 phosphorylation. 1879 15

Activation of the RET gene by chromosomal rearrangements generating RET/PTC oncogenes is a frequent, early, and causative event in papillary thyroid carcinoma (PTC). We have previously shown that, in human primary thyrocytes, RET/PTC1 induces a transcriptional program including the MET proto-oncogene. In PTCs, beta-catenin is frequently mislocated to the cytoplasm nucleus. We investigated the interplay between Ret/ptc1 signaling and Met in regulating the proinvasive phenotype and beta-catenin localization in cellular models of human PTC. Here, we show that Met protein is expressed and is constitutively active in human thyrocytes exogenously expressing RET/PTC1 as well as a mutant (Y451F) devoid of the main Ret/ptc1 multidocking site. Both in transformed thyrocytes and in the human PTC cell line TPC-1, Ret/ptc1-Y451-dependent signaling and Met cooperated to promote a proinvasive phenotype. Accordingly, gene/functional silencing of either RET/PTC1 or MET abrogated early branching morphogenesis in TPC-1 cells. The same effect was obtained by blocking the common downstream effector Akt. Y451 of Ret/ptc1 was required to promote proliferation and nuclear translocation of beta-catenin, suggesting that these oncogene-driven effects are Met-independent. Pharmacologic inhibition of Ret/ptc1 and Met tyrosine kinases by the multitarget small molecule RPI-1 blocked cell proliferation and invasive ability and dislocated beta-catenin from the nucleus. Altogether, these results support that Ret/ptc1 cross talks with Met at transcriptional and signaling levels and promotes beta-catenin transcriptional activity to drive thyrocyte neoplastic transformation. Such molecular network, promoting disease initiation and acquisition of a proinvasive phenotype, highlights new options to design multitarget therapeutic strategies for PTCs.
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PMID:RET/PTC1-driven neoplastic transformation and proinvasive phenotype of human thyrocytes involve Met induction and beta-catenin nuclear translocation. 1910 27

RET/papillary thyroid carcinoma (PTC), TRK-T, or activating mutations of Ras and BRaf are frequent genetic alterations in PTC, all leading to the activation of the extracellular-regulated kinase (Erk) cascade. The aim of this study was to investigate the role of calmodulin-dependent kinase II (CaMKII) in the signal transduction leading to Erk activation in PTC cells. In normal thyroid cells, CaMKII and Erk were in the inactive form in the absence of stimulation. In primary PTC cultures and in PTC cell lines harboring the oncogenes RET/PTC-1 or BRaf(V600E), CaMKII was active also in the absence of any stimulation. Inhibition of calmodulin or phospholipase C (PLC) attenuated the level of CaMKII activation. Expression of recombinant RET/PTC-3, BRaf(V600E), or Ras(V12) induced CaMKII activation. Inhibition of CaMKII attenuated Erk activation and DNA synthesis in thyroid papillary carcinoma (TPC-1), a cell line harboring RET/PTC-1, suggesting that CaMKII is a component of the Erk signal cascade in this cell line. In conclusion, PTCs contain an active PLC/Ca(2+)/calmodulin-dependent signal inducing constitutive activation of CaMKII. This kinase is activated by BRaf(V600E), oncogenic Ras, and by RET/PTC. CaMKII participates to the activation of the Erk pathway by oncogenic Ras and RET/PTC and contributes to their signal output, thus modulating tumor cell proliferation.
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PMID:The Ca2+-calmodulin-dependent kinase II is activated in papillary thyroid carcinoma (PTC) and mediates cell proliferation stimulated by RET/PTC. 1990 42


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