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

The major determinants of 5-flurouracil (5-FU) response would seem, based on accumulated literature, to be thymidylate synthase (TYMS, TS) expression levels, TS gene modifications, and TP53 status. We tested 5-FU sensitivity in yeast and human cancer cell models in which TS or TP53 alleles and expression were varied. Polymorphic TS tandem repeat status, TS expression levels reported, TS intragenic mutations, and TP53 status in outbred and experimental cancer cell lines did not predict 5-FU sensitivity or resistance. Novel observations included a dose-resistant persistence of unbound TS protein in many cancers and, upon 5-FU treatment of the colon cancer cell line, HCT116, evidence of allelic switching favoring transcripts of the mutant TS allele. The reported alleles having an intragenic mutation could not be causally associated with major degrees of 5-FU sensitivity. In yeast, TS protein was altered upon treatment with FdUMP, but 5-FU toxicity seemed to be largely RNA-based, being rescued by uridine rather than by thymidine. Cancer cell lines were also rescued from 5-FU toxicity with uridine rather than thymidine. Additionally, a TS (CDC21) knockout yeast strain, obviating any potential role for TS protein as a target, was hypersensitive to 5-FU. When denatured proteins from cancer cells treated with radiolabeled 5-FU were labeled, species with alternative molecular weights other than TS were visualized, providing further evidence for alternative 5-FU protein targets. These data emphasize that TS and TP53 status do not consistently explain the variance in responses of fluoropyrimidine-treated cancer cells, in part due to RNA-based toxicity.
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PMID:Limits to thymidylate synthase and TP53 genes as predictive determinants for fluoropyrimidine sensitivity and further evidence for RNA-based toxicity as a major influence. 1915 91

We evaluated the usefulness of the level of thymidylate synthase(TS)and dihydropyrimidine dehydrogenase(DPD) activity as prognostic factors and indicators for selection of chemotherapy regimens. Between November 1997 and March 1999, fifty-seven patients with stages I - IIIa primary breast cancer were registered. Using recurrence risk categories, they were classified into TAM monotherapy, TAM+oral 5-FU, and TAM+CMF groups(each were standard regimens at the time), and underwent postoperative adjuvant chemotherapy. The relationship between prognosis and the TS level and DPD activity, in addition to conventional risk factors, was examined. The recurrence-free survival time curve showed significant differences when stratified by tumor diameter, ER expression, and TS levels, but not by menopausal status, nodal status, surgical method, p53 expression, DPD activity, or HER2 expression. These results suggest that the TS level is useful as a prognostic factor for breast cancer.
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PMID:[Clinical significance of intratumoral TS levels and DPD activity in breast cancer]. 1929 64

Despite recent therapeutic advances, the response rates to chemotherapy for patients with metastatic colon cancer remain at approximately 50% with the fluoropyrimidine, 5-fluorouracil (5-FU), continuing to serve as the foundation chemotherapeutic agent for the treatment of this disease. Previous studies have demonstrated that overexpression of thymidylate synthase (TS) is a key determinant of resistance to 5-FU-based chemotherapy. Therefore, there is a significant need to develop alternative therapeutic strategies to overcome TS-mediated resistance. In this study, we demonstrate that the histone deacetylase inhibitors (HDACi) vorinostat and LBH589 significantly downregulate TS gene expression in a panel of colon cancer cell lines. Downregulation of TS was independent of p53, p21 and HDAC2 expression and was achievable in vivo as demonstrated by mouse xenograft models. We provide evidence that HDACi treatment leads to a potent transcriptional repression of the TS gene. Combination of the fluoropyrimidines 5-FU or FUdR with both vorinostat and LBH589 enhanced cell cycle arrest and growth inhibition. Importantly, the downstream effects of TS inhibition were significantly enhanced by this combination including the inhibition of acute TS induction and the enhanced accumulation of the cytotoxic nucleotide intermediate dUTP. These data demonstrate that HDACi repress TS expression at the level of transcription and provides the first evidence suggesting a direct mechanistic link between TS downregulation and the synergistic interaction observed between HDACi and 5-FU. This study provides rationale for the continued clinical evaluation of HDACi in combination with 5-FU-based therapies as a strategy to overcome TS-mediated resistance.
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PMID:Histone deacetylase inhibitors suppress thymidylate synthase gene expression and synergize with the fluoropyrimidines in colon cancer cells. 1938 49

The esophageal squamous cell carcinoma is multifactorial disease involving genetic and environmental factors. The paper presents most important human data on the polymorphisms of selected genes that have been linked with higher risk of the neoplasm. The most widely studied group were genes encoded molecules engaged in biotransformations of xenobiotics, in particular potential carcinogens, like alcohol (ADH2) and aldehyde (ALDH2) dehydrogenases, various isoenzymes of cytochrome P450 (CYP1A1, CYP2E1) and glutathione S-transferase (GSTM1, GSTT1, GSTP1). High interest was also put for polymorphism in DNA repair genes, i.e., OGG1, XRCC1, XPD, XPG and MGMT as well as genes associated with nucleotide biosyntesis like methylenotetrahydrofolate reductase and thymidylate synthase and in control of cell cycle and apoptosis e.g., p53, Fas, FasL or TNF. Furthermore, it was revealed that predisposition to cancer in certain individual could be determined by coexistence of unprofitable allele of a few genes. Introduction of genetic screening test allows effective, purpose-oriented methods of prevention and in patients suffered from the cancer--application of optimal therapy and minimization of side-effects.
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PMID:[Genetic base of esophageal squamous cell carcinoma susceptibility]. 1938 10

Locally advanced rectal cancer (LARC) is currently treated with neoadjuvant chemoradiation. Although approximately 45% of patients respond to neoadjuvant therapy with T-level downstaging, there is no effective method of predicting which patients will respond. Molecular biomarkers have been investigated for their ability to predict outcome in LARC treated with neoadjuvant chemotherapy and radiation. A literature search using PubMed resulted in the initial assessment of 1,204 articles. Articles addressing the ability of a biomarker to predict outcome for LARC treated with neoadjuvant chemotherapy and radiation were included. Six biomarkers met the criteria for review: p53, epidermal growth factor receptor (EGFR), thymidylate synthase, Ki-67, p21, and bcl-2/bax. On the basis of composite data, p53 is unlikely to have utility as a predictor of response. Epidermal growth factor receptor has shown promise as a predictor when quantitatively evaluated in pretreatment biopsies or when EGFR polymorphisms are evaluated in germline DNA. Thymidylate synthase, when evaluated for polymorphisms in germline DNA, is promising as a predictive biomarker. Ki-67 and bcl-2 are not useful in predicting outcome. p21 needs to be further evaluated to determine its usefulness in predicting outcome. Bax requires more investigation to determine its usefulness. Epidermal growth factor receptor, thymidylate synthase, and p21 should be evaluated in larger prospective clinical trials for their ability to guide preoperative therapy choices in LARC.
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PMID:Biomarkers for response to neoadjuvant chemoradiation for rectal cancer. 1948 Sep 68

Despite advances in anticancer treatment, lung cancer still has poor prognosis. Recently, a cancer stem cell (CSC) hypothesis has emerged describing a small subset of tumor cells with stem cell properties. CSCs found in many solid tumors express CD133 antigen on the cell surface. The presence of CSC is correlated with poor survival of patients with glioblastomas, colon or prostate cancers. In this study, we evaluated whether CD133 expression in non-small cell lung cancer (NSCLC) has a prognostic value in patients' survival. We also analyzed whether CD133 positivity of NSCLC correlates with the expression of resistance-related proteins, angiogenic factors, oncogenes, proliferative activity or apoptosis. CD133 expression was retrospectively examined in a total of 88 cases of previously untreated NSCLC by immunohistochemistry. We found no correlation between CD133 positivity or the amount of CD133(+) cells with NSCLC patients' survival, expression of oncogenes c-myc, c-N-ras, c-jun, c-fos, c-erbB1, c-erbB2 or p53, angiogenic factors VEGF, VEGFR-1, FGF, FGFR-1, tissue factor and with proliferative activity or apoptosis in NSCLC tissues. However, there was a significant association between the expression of resistance-related proteins glutathione S-transferase, thymidylate synthase, catalase, O(6)-methylguanine-DNA methyltransferase and p170 and CD133. Because CD133 expression is linked to a resistant phenotype, detection of CD133(+) cells may be useful to predict efficacy of cytotoxic therapy but CD133 is not a strong prognostic parameter for survival of patients with NSCLC.
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PMID:CD133 is indicative for a resistance phenotype but does not represent a prognostic marker for survival of non-small cell lung cancer patients. 1967 44

Aloe-emodin, one of the anthraquinones, has been shown to have anticancer activity in different kinds of human cancer cell lines. Therefore, the purpose of this study was to investigate the anti-cancer effect of aloe-emodin on human tongue squamous carcinoma SCC-4 cells. The results indicated that aloe-emodin induced cell death through S-phase arrest and apoptosis in a dose- and time-dependent manner. Treatment with 30 microM of aloe-emodin led to S-phase arrest through promoted p53, p21 and p27, but inhibited cyclin A, E, thymidylate synthase and Cdc25A levels. Aloe-emodin promoted the release of apoptosis-inducing factor (AIF), endonuclease G (Endo G), pro-caspase-9 and cytochrome c from the mitochondria via a loss of the mitochondrial membrane potential (DeltaPsi(m)) which was associated with a increase in the ratio of B-cell lymphoma 2-associated X protein (Bax)/B cell lymphoma/leukemia-2 (Bcl-2) and activation of caspase-9 and -3. The free radical scavenger N-acetylcysteine (NAC) and caspase inhibitors markedly blocked aloe-emodin-induced apoptosis. Aloe-emodin thus induced apoptosis in the SCC-4 cells through the Fas/death-receptor, mitochondria and caspase cascade. Aloe-emodin could be a novel chemotherapeutic drug candidate for the treatment of human tongue squamous cancer in the future.
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PMID:Aloe-emodin induces cell death through S-phase arrest and caspase-dependent pathways in human tongue squamous cancer SCC-4 cells. 2003 98

We have developed a new approach to systematically study post-transcriptional regulation in a small number of cells. Actively translating mRNAs are associated with polysomes and the newly synthesized peptide chains are closely associated with molecular chaperones such as hsp70s, which assist in the proper folding of nascent polypeptides into higher ordered structures. These chaperones provide an anchor with which to separate actively translating mRNAs associated with polysomes from free mRNAs. Affinity capture beads were developed to capture hsp70 chaperones associated with the polysome complexes. The isolated actively translating mRNAs were used for high-throughput expression profiling analysis. Feasibility was demonstrated using an in vitro translation system with known translationally regulated mRNA transcript thymidylate synthase (TS). We further developed the approach using HCT-116 colon cancer cells with both TS and p53 as positive controls. The steady-state levels of TS and p53 mRNAs were unaltered after 5-fluorouracil treatment as assessed by real-time qRT-PCR analysis. In contrast, the protein expression and polysome-associated mRNA levels of both genes were increased. These differences in translational rate were revealed with our new approach from 500 cells. This technology has the potential to make investigation of translational control feasible with limited quantities of clinical specimens.
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PMID:Translational control analysis by translationally active RNA capture/microarray analysis (TrIP-Chip). 2012 31

Resistance to chemotherapy is a major issue in treating malignant diseases. 5-Fluorouracil (5-FU) is the drug of choice in managing colorectal cancer (CRC) patients. However, 5-FU resistance leads to eventual treatment failure. Therefore, delaying or reversing the onset of 5-FU resistance will benefit these terminally ill patient populations. A metabolite of 5-FU irreversibly binds thymidylate synthase (TS) thus inhibiting its activity. Many studies demonstrated that these resistant patients had an increased intratumoral TS level. We used TS-siRNA to reduce TS and resensitize HT29FU CRC cells back to this uracil analogue. We exposed the CRC cell line HT29 to an increasing concentration of 5-FU or 5-fluorouridine (FUR) and established a derivative cell line (HT29FU and HT29FUR). Using real-time polymerase chain reaction (PCR) and Western immunodetection assays, we analyzed the expression of TS and p53 mRNA and protein in control and experimental groups. Cytotoxicity to 5-FU was determined by reduction of 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT assay) or trypan blue dye exclusion assay. The HT29FU and HT29FUR cells have a distinct morphology: they are generally asteroid shaped. The half maximal inhibitory concentration (IC(50)) values for the resistant cell line for 5-FU is over 148 microM compared to 5 microM for the sensitive parental cell line. The resistant cell lines expressed more of TS and less of p53. TS-siRNA suppressed TS only. Other pathways were not significantly altered. It also marginally (20%) re-sensitized resistant cells to 5-FU. Restoration of partial sensitivity to 5-FU by TS-siRNA reiterates the primacy of the DNA synthesis pathway in 5-FU mode of action. We speculate that the short half-life of the transiently transfected siRNA may contribute to the marginal restoration of sensitivity. By integrating TS-siRNA expression vector into the genome and regulating its expression, we may be able to reverse 5-FU resistance and make the cells as sensitive as the parental cell line.
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PMID:Chronic exposure of colorectal cancer cells in culture to fluoropyrimidine analogs induces thymidylate synthase and suppresses p53. A molecular explanation for the mechanism of 5-FU resistance. 2053 Apr 21

Response rates to cytotoxics in gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) vary; recent trials demonstrated lack of objective response rates in up to 70% of patients. Identification of predictive therapeutic biomarkers would be beneficial in the treatment of GEP. Selected markers with known or suspected capability of predicting response to cytotoxics or prognosis (Ki-67, p53, multidrug resistance protein-1 (MDR1), Akt, thymidylate synthase (TS), phosphatase and tensin homolog (PTEN), CA9, cluster of differentiation 34 (CD34), vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF)-1, mismatch repair gene - human mutL homolog 1 (hLMH1), and Bcl-2) were analyzed using immunohistochemisrtry in 60 treatment-naive patients receiving chemotherapy (n=46) or chemoembolization (n=14) for inoperable advanced and/or metastatic GEP and correlated with prognosis (survival and response rates). Therapy included systemic chemotherapy with streptozotocin (n=28), doxorubicin (n=14), 5-fluorouracil (n=18), and etoposide/cisplatinum (n=16), or chemoembolization (streptozotocin, 9; doxorubicin, 5). Factors associated with overall survival in the entire cohort were Ki-67, P<0.001; tumor grade, P<0.001; tumor differentiation, P<0.001; CA9, P=0.004; Akt, P=0.01; HIF-1, P<0.001; p53, P<0.0001; and hMLH1, P=0.005. Markers associated with treatment response included overall group: Akt and PTEN (P=0.05 and 0.05 respectively); streptozotocin: Akt (P=0.07), TS (P=0.02), and PTEN (P=0.017); doxorubicin: Ki-67 (P=0.05), Akt (P=0.06), and CA9 (P=0.02). At multivariate analysis, Akt was significantly associated with a nonresponse to therapy (objective response (OR): 0.2 (0.05-0.8)). For patients receiving only systemic chemotherapy (n=46), PTEN (0.04) and hLMH1 (0.03) were correlated with treatment response and for individual molecules were streptozotocin: PTEN (P=0.008) and hLMH1 (0.07); doxorubicin: Akt (P=0.09), CA9 (P=0.09), and hLMH1 (P=0.09). These results demonstrate a number of new prognostic biomarkers in GEP-NET, and in addition, response to chemotherapy was correlated with a simple panel of selected markers (such as CA9, Akt, PTEN, TS, and hLMH1).
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PMID:Molecular markers associated with response to chemotherapy in gastro-entero-pancreatic neuroendocrine tumors. 2057 Sep 57


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