Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ectopic expression of conditional murine p53 (p53val135) and oncogenic ras is enough to induce a senescent-like growth arrest at the restrictive temperature. We took advantage of this cellular system to identify new key players in the ras/p53-induced senescence. Applying a retroviral-based genetic screen, we obtained an antisense RNA fragment against PPP1CA, the catalytic subunit of protein phosphatase 1alpha, whose loss of function bypasses ras/p53-induced growth arrest and senescence. Expression of a specific short hairpin (sh)RNA against PPP1CA impairs the p53-dependent induction of p21 after DNA damage and blocks the subsequent pRb dephosphorylation, thus bypassing p53-induced arrest. We found that oncogenic ras promotes an increase in the intracellular level of ceramides together with an increase in the PPP1CA protein levels. Addition of soluble ceramide to the cells induced a senescence phenotype that is blocked through PPP1CA downregulation by specific shRNA. Analysis of human tumors suggests that one of the PPP1CA alleles might be lost in a high percentage of carcinomas such as kidney and colorectal. The overexpression of two out of five PPP1CA alternative spliced variants reduced tumor cell growth and the downregulation of the protein to hemizygosity increased the anchorage-independent growth. We propose that oncogenic stress induced by ras causes ceramide accumulation, therefore, increasing PPP1CA activity, pRb dephosphorylation and onset of the p53-induced arrest, contributing to tumor suppression.
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PMID:PPP1CA contributes to the senescence program induced by oncogenic Ras. 1820 81

The scaffold protein spinophilin (Spn, PPP1R9B) is one of the regulatory subunits of phosphatase-1a (PP1), targeting it to distinct subcellular locations and to its target. Loss of Spn reduces PPP1CA levels, thereby maintaining higher levels of phosphorylated pRb. This effect contributes to an increase in p53 activity. However, in the absence of p53, reduced levels of Spn increase the tumourigenic properties of cells. In addition, Spn knockout mice have a reduced lifespan, an increased number of tumours and increased cellular proliferation in some tissues, such as the mammary ducts. In addition, the combined loss of Spn and p53 activity leads to an increase in mammary carcinomas, confirming the functional relationship between p53 and Spn. In this paper, we report that Spn is absent in 20% and reduced in another 37% of human lung tumours. Spn reduction correlates with malignant grade. Furthermore, the loss of Spn also correlates with p53 mutations. Analysis of miRNAs in a series of lung tumours showed that miRNA106a* targeting Spn is over-expressed in some patients, correlating with decreased Spn levels. Proof-of-concept experiments over-expressing miRNA106a* or Spn shRNA in lung tumour cells showed increased tumourigenicity. In conclusion, our data showed that miRNA106a* over-expression found in lung tumours might contribute to tumourigenesis through Spn down-regulation in the absence of p53.
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PMID:Down-regulation of spinophilin in lung tumours contributes to tumourigenesis. 2159 52

The scaffold protein Spinophilin (SPN) is a regulatory subunit of phosphatase1a located at 17q21.33. This region is frequently associated with microsatellite instability and LOH containing a relatively high density of known tumor suppressor genes, including BRCA1. Several linkage studies have suggested the existence of an unknown tumor suppressor gene distal to BRCA1. Spn may be this gene, but the mechanism through which this gene makes its contribution to cancer has not been described. In this study, we aimed to determine how loss of Spn may contribute to tumorigenesis. We explored the contribution of SPN to PP1a-mediated Rb regulation. We found that the loss of Spn downregulated PPP1CA and PP1a activity, resulting in a high level of phosphorylated Rb and increased ARF and p53 activity. However, in the absence of p53, reduced levels of SPN enhanced the tumorigenic potential of the cells. Furthermore, the ectopic expression of SPN in human tumor cells greatly reduced cell growth. Taken together, our results demonstrate that the loss of Spn induces a proliferative response by increasing Rb phosphorylation, which, in turn, activates p53, thereby neutralizing the proliferative response. We suggest that Spn may be the tumor suppressor gene located at 17q21.33 acting through Rb regulation.
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PMID:Spinophilin acts as a tumor suppressor by regulating Rb phosphorylation. 2202 30

Diffuse large B cell lymphoma (DLBCL) is the most common hematological malignancy and is one of the most frequent non-Hodgkin lymphomas. Large-scale genomic studies have defined genetic drivers of DLBCL and their association with functional and clinical outcomes. However, the lymphomagenesis of DLBCL is yet to be fully understood. In the present study, four computational tools OncodriveFM, OncodriveCLUST, integrated Cancer Genome Score and Driver Genes and Pathways were used to detect driver genes and driver pathways involved in DLBCL. The aforementioned tools were also used to perform an integrative investigation of driver genes, including co-expression network, protein-protein interaction, copy number variation and survival analyses. The present study identified 208 driver genes and 31 driver pathways in DLBCL. IGLL5, MLL2, BTG2, B2M, PIM1, CARD11 were the top five frequently mutated genes in DLBCL. NOTCH3, LAMC1, COL4A1, PDGFRB and KDR were the 5 hub genes in the blue module that were associated with patient age. TP53, MYC, EGFR, PTEN, IL6, STAT3, MAPK8, TNF and CDH1 were at the core of the protein-protein interaction network. PRDM1, CDKN2A, CDKN2B, TNFAIP3, RSPO3 were the top five frequently deleted driver genes in DLBCL, while ACTB, BTG2, PLET1, CARD11, DIXDC1 were the top five frequently amplified driver genes in DLBCL. High EIF3B, MLH1, PPP1CA and RECQL4 expression was associated with decreased overall survival rate of patients with DLBCL. High XPO1 and LYN expression were associated with increased overall survival rate of patients with DLBCL. The present study improves the understanding of the biological processes and pathways involved in lymphomagenesis. The driver genes, EIF3B, MLH1, PPP1CA, RECQL4, XPO1 and LYN, pave the way for developing prognostic biomarkers and new therapeutic strategies for DLBCL.
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PMID:Comprehensive characterization of driver genes in diffuse large B cell lymphoma. 3256 64