Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cellular transcription factor E2F, previously identified as a component of early adenovirus transcription, has now been shown to be important in cell proliferation control. E2F appears to be a functional target for the action of the tumor suppressor protein Rb that is encoded by the retinoblastoma susceptibility gene. The disruption of this E2F-Rb interaction, as well as a complex involving E2F in association with the cell cycle-regulated cyclin A-cdk2 kinase complex, may be a common mechanism of action for the oncoproteins encoded by the DNA tumor viruses.
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PMID:E2F: a link between the Rb tumor suppressor protein and viral oncoproteins. 141 35

Hyperparathyroidism is a central component of multiple endocrine neoplasia type 1 (MEN 1), and both sporadic and familial forms of parathyroid disease may share certain pathogenetic features. We recently identified a gene that is clonally rearranged with the PTH locus in a subset of sporadic parathyroid adenomas. This candidate oncogene, PRAD1 (previously D11S287), appears to contribute to parathyroid tumorigenesis in a fashion analogous to activation of C-MYC or BCL-2 by rearrangement with tissue-specific enhancers of the immunoglobulin genes in B-lymphoid neoplasia. The PRAD1 gene maps to 11q13 and has been linked to the BCL-1 breakpoint locus, although not to the most tightly linked MEN 1 markers, by pulsed field gel electrophoresis. PRAD1 may, in fact, be the long-sought BCL-1 lymphoma oncogene. PRAD1 encodes a novel type of cyclin protein and thus may normally function in controlling the cell cycle, perhaps through direct interaction with cdc2 or a related kinase. PRAD1's possible primary, or more likely secondary, involvement in the pathogenesis of MEN 1-related tumors is unknown and under investigation.
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PMID:PRAD1 (cyclin D1): a parathyroid neoplasia gene on 11q13. 148 73

Senescent human diploid fibroblasts (HDF) contain no detectable cdc2 mRNA or p34cdc2 protein. Similarly, young quiescent HDF have only low levels of cdc2 mRNA and protein. After serum stimulation, quiescent HDF accumulate increasing amounts of cdc2 mRNA and protein and go through DNA synthesis and mitosis. In contrast, serum-stimulated senescent HDF fail to accumulate detectable amounts of cdc2 mRNA and protein and fail to enter S phase. Mitosis is likewise deficient in senescent cells even when they have been induced to synthesize DNA by simian virus 40 large tumor antigen. Since p34cdc2 or its homologues appear to be required for DNA synthesis and mitosis in eukaryotes, a lack of these molecules in serum-stimulated senescent HDF could be an important reason for their inability to enter S phase or mitosis. Nuclear microinjection of cdc2 DNA into senescent HDF causes rounding up of the cells but no induction of DNA synthesis. Since cyclins A and B are important cofactors of the protein kinase activity of p34cdc2 or its homologues, we analyzed expression of these genes in serum-stimulated senescent HDF and determined that they contain little or no cycA or cycB mRNA. These deficiencies may be relevant to the lack of DNA synthesis and mitosis in senescent HDF.
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PMID:Senescent cells fail to express cdc2, cycA, and cycB in response to mitogen stimulation. 172 13

p34cdc2 is a protein kinase that has an important role in controlling cell cycle progression and may regulate tumor suppressor gene activity. In this work, we show that the arrest of cell growth and induction of differentiation in a tumorigenic neuroblastoma cell line by retinoic acid (RA) is associated with a 75-fold decrease in the level of p34cdc2 protein. The RA induced decrease in p34cdc2 levels does not simply reflect the arrest of cell growth, because p34cdc2 levels are not reduced when neuroblastoma cells are growth arrested by nutrient deprivation. Furthermore, dephosphorylation of the tumor suppressor gene product RB, a substrate for the p34cdc2 kinase activity, is observed only when p34cdc2 levels are decreased in RA treated cells. These studies link regulation of cdc2 level, RB phosphorylation state, and induction of differentiation by RA and suggest that alterations in the cdc2 gene or in genes controlling its regulation contribute to tumorigenesis.
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PMID:Retinoic acid negatively regulates p34cdc2 expression during human neuroblastoma differentiation. 175 5

Hydrolysis of the neurotransmitter acetylcholine by acetylcholinesterase (ACHE) and butyrylcholinesterase (BCHE) is the rate-limiting step in the termination of cholinergic signaling at neuromuscular junctions. A growing body of evidence suggests that these enzymes also play a role in tumorigenesis. The ACHE and BCHE genes are amplified, mutated, and/or aberrantly expressed in a variety of human tumor types. These changes could be the result of chromosome breakage, since there is an unusually high frequency of chromosomal abnormalities near the map positions of these genes (3q26-ter and 11p-ter, respectively) in such tumors, particularly hemopoietic malignancies. Both ACHE and BCHE contain the consensus peptide motif S/T-P-X-Z, which is found in many substrates of cdc2-related protein kinases. Here we consider the intriguing possibility that phosphorylation by cdc2-related kinases may be the molecular mechanism linking cholinesterases with tumor cell proliferation. We also discuss the notion that inhibition of these enzymes by commonly used organophosphorous poisons may be tumorigenic in humans.
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PMID:A role for cholinesterases in tumorigenesis? 182 94

How does a quiescent cell decide to re-enter the cell cycle and start replicating its DNA? What controls cell proliferation? These are fundamental questions that have to be solved in order to understand the mechanisms of oncogenesis. Some recent data have provided clues about how signal transduction pathways may be connected to the cell cycle. A protein kinase cascade starting from the membrane growth factor receptor is thought to be involved in transducing extracellular stimuli to the master switches of the cell cycle control machinery. The recently identified extracellular-signal regulated kinases (ERKs) appear to play an important role in this pathway. Expression of cyclins, which are regulatory subunits of the universal cell cycle oscillator cdc2, may also be controlled through this kinase cascade. The products of tumor suppressor genes Rb and p53 also play an important role in regulating cell proliferation by interfering with the cell cycle pathway. Here, I will review and discuss the importance of these different new results.
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PMID:From growth to cell cycle control. 184 42

Isolated interphase lamin C, obtained from Ehrlich ascites tumor cells, was digested by Lys-C endoproteinase, the resulting peptides separated by reversed-phase HPLC and subjected to microsequencing in order to identify phosphorylation sites in interphase and following phosphorylation in vitro by cdc2-kinase, protein kinase C (PKC) and protein kinase A (PKA), respectively. Nuclear lamin C showed partial phosphorylation of Ser392 and Ser409, and possibly Ser407 in interphase. Phosphorylation was increased in response to cdc2-kinase at Ser390 and Ser392 and to PKC at Ser572. The N-terminal peptide (aa 1-32) containing consensus sequences for the 3 kinases was phosphorylated by cdc2-kinase, PKC and PKA. The sequence data suggests that multiple molecular switches via lamina modification control the dynamic behaviour of the nucleoskeleton during the cell cycle.
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PMID:Identification of phosphorylation sites on murine nuclear lamin C by RP-HPLC and microsequencing. 195 8

The retinoblastoma gene product (RB) is a nuclear protein which has been shown to function as a tumor suppressor. It is phosphorylated from S to M phase of the cell cycle and dephosphorylated in G1. This suggests that the function of RB is regulated by its phosphorylation in the cell cycle. Ten phosphotryptic peptides are found in human RB proteins. The pattern of RB phosphorylation does not change from S to M phases of the cell cycle. Hypophosphorylated RB prepared from insect cells infected with an RB-recombinant baculovirus is used as a substrate for in vitro phosphorylation reactions. Of several protein kinases tested, only cdc2 kinase phosphorylates RB efficiently and all 10 peptides can be phosphorylated by cdc2 in vitro. Removal of cdc2 from mitotic cell extracts by immunoprecipitation causes a concomitant depletion of RB kinase activity. These results indicate that cdc2 or a kinase with similar substrate specificity is involved in the cell cycle-dependent phosphorylation of the RB protein.
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PMID:Retinoblastoma cancer suppressor gene product is a substrate of the cell cycle regulator cdc2 kinase. 200 61

The phosphorylation pattern of simian virus 40 (SV40) large tumor (T) antigen purified from insect cells infected with a recombinant baculovirus was compared with that reported previously for T antigen from SV40-infected monkey cells. The specific activity of metabolic phosphate labeling of baculovirus T antigen was reduced, and the phosphopeptide map of the baculovirus protein, while qualitatively similar to that of lytic T, revealed several quantitative differences. The most striking difference was the prominence in the baculovirus map of peptides containing phosphothreonine 124. These peptides are known to arise from other phosphopeptides upon dephosphorylation of neighboring serines, suggesting that baculovirus T may be underphosphorylated at these serines and perhaps other sites. Functional assays used to further investigate the phosphorylation state of the baculovirus protein included SV40 DNA binding after enzymatic dephosphorylation with alkaline phosphatase and after phosphorylation by a murine homolog of cdc2 protein kinase. The results imply that baculovirus T antigen is underphosphorylated, in particular at those serine residues whose phosphorylation is responsible for down regulation of DNA-binding activity at site II in the core origin of DNA replication. In contrast, no evidence for a functionally significant underphosphorylation at threonine 124 could be found.
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PMID:Altered phosphorylation pattern of simian virus 40 T antigen expressed in insect cells by using a baculovirus vector. 216 68

P16 was originally discovered by its ability to interact with CDK4 and to specifically inhibit the catalytic activity of the CDK4/D1 kinase. Increased attention has focused on the p16 gene because of its location on chromosome 9p21, a region involved in chromosomal rearrangements in a large number of tumor types. The p16 gene is also mutated in a large number of tumor cell lines and primary tumor cells. Furthermore, linkage analysis studies suggest that the p16 gene is involved in familial melanoma susceptibility. Due to the oncogenic potential of mutations in this tumor suppressor, it is important to identify and characterize those mutations which alter p16 activity. We have performed a systematic analysis of melanoma associated p16 mutants and of mutants generated in charge to Ala mutagenesis. Using microtiter plate assays to measure both p16-cdk4 binding and cdk4/D1 kinase activity, we show here that the melanoma associated mutants are defective, as are some of the Ala mutants. These results support the idea that p16 mutation, via its deregulation of the cdk4/D1 pathway, is of biological significance in the development of melanoma. Furthermore, we have defined a region within the p16 molecule in which changes are likely to result in a defective protein.
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PMID:Biochemical and mutagenic analysis of the melanoma tumor suppressor gene product/p16. 747 20


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