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)

Breast tumor cells are relatively refractory to apoptosis in response to modalities which induce DNA damage such as ionizing radiation and the topoisomerase II inhibitor, adriamycin. Various factors which may modulate the apoptotic response to DNA damage include the p53 status of the cell, levels and activity of the Bax and Bcl-2 families of proteins, activation of NF-kappa B, relative levels of insulin like growth factor and insulin-like growth factor binding proteins, activation of MAP kinases and PI3/Akt kinases, (the absence of) ceramide generation and the CD95 (APO1/Fas) signaling pathway. Prolonged growth arrest associated with replicative senescence may represent an alternative and reciprocal response to DNA-damage induced apoptosis that is p53 and/or p21waf1/cip1 dependent while delayed apoptosis may occur in p53 mutant breast tumor cells which fail to maintain the growth-arrested state. Clearly, the absence of an immediate apoptotic response to DNA damage does not eliminate other avenues leading to cell death and loss of self-renewal capacity in the breast tumor cell. Nevertheless, prolonged growth arrest (even if ultimately succeeded by apoptotic or necrotic cell death) could provide an opportunity for subpopulations of breast tumor cells to recover proliferative capacity and to develop resistance to subsequent clinical intervention.
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PMID:Growth arrest and cell death in the breast tumor cell in response to ionizing radiation and chemotherapeutic agents which induce DNA damage. 1107 87

Pancreatic cancer has an incidence of approximately 8 to 10 cases per 100,000 citizens in Western industrialized countries, and the incidence has been increasing throughout the last decades. Insensitivity to antigrowth and apoptotic signals as well as self-sufficiency in growth signals are hallmarks of malignant growth. Pancreatic cancers often exhibit alterations in growth inhibitory pathways such as Smad4 mutations and Smad6 and Smad7 overexpression, and evade apoptosis through p53 mutations and aberrant expression of apoptosis regulating genes. In addition, in pancreatic cancer a variety of growth factors are expressed at increased levels. For example, the concomitant presence of the EGF-receptor and its ligands EGF, TGF-alpha, and/or amphiregulin is associated with enhanced tumor aggressiveness and shorter survival periods following tumor resection. Furthermore, a number of other growth factors and their receptors, such as fibroblast growth factors, nerve growth factor, platelet-derived growth factors, and insulin-like growth factors and their respective receptors are expressed at increased levels in pancreatic cancer and are thought to contribute to its malignant phenotype. Taken together, the disturbance of growth inhibitory and apoptotic pathways and the abundance of growth promoting factors give pancreatic cancer cells a distinct growth advantage which clinically results in rapid tumor progression and poor survival prognosis.
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PMID:Growth factors and their receptors in pancreatic cancer. 1113 19

The purpose of this report was the initiation and further maintenance of tumor cells from a primary larynx squamous cell carcinoma. A tumor fragment was mechanically dissociated, the cells were grown in RPMI medium, being the primary culture dependent on the presence of epidermal growth factor and insulin; during subsequent passages the adaptation to conventional growth conditions was obtained. Cells grew in monolayer with an epitheliod shape, showing a pavement-like arrangement; at confluence, cells piled up without contact inhibition maintaining the same morphology. Population doubling time was about 48 h with a colony-forming efficiency of 10%. Immunocytochemical characterization was performed with a panel of monoclonal antibodies reactive against tumor associated antigens, including mucin glycoproteins and related carbohydrate antigens, carcinoembryonic antigen (CEA), p53 as well as cytokeratins, vimentin and desmin. T201 expressed CEA, sialyl Lewis x, Lewis x, Lewis y, MUC1 mucin, Tn hapten, p53, vimentin and cytokeratins. On the other hand, a modal chromosome diploid number of 46 occurring in 74% of cells was detected. Present data confirmed that the methodology employed was adequate for the establishment and characterization of a new cell line which can provide a useful model to study biological and immunological aspects of larynx squamous cell carcinoma.
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PMID:Establishment and characterization of a cell line (T201) derived from a human larynx squamous cell carcinoma. 1125 Nov 67

Altered cell and tissue differentiation is characteristic of premalignant lesions long before they become invasive and metastatic. One approach to controlling preneoplastic lesions is to block their expansion with non-toxic agents that suppress cell proliferation and induce apoptosis. Here, we show that ellagic acid, a natural, dietary phenolic antioxidant when given at 10(-5) M for 48 hours to colon cancer cells (SW 480), induced down regulation of insulin like growth factor IGF-II, activated p21(waf1/Cip1), mediated a cumulative effect on G1/S transition phase and caused apoptotic cell death. SW480 colon cancer cells expressed significant mRNA levels for the mitogenic insulin like growth factor (IGF-II). Collectively, these observations suggest that growth inhibition by ellagic acid is mediated by signaling pathways that mediate DNA damage, triggers p53, which in turn activates p21 and at the same time alters the growth factor expression, resulting in the down regulation of IGF-II.
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PMID:IGF-II down regulation associated cell cycle arrest in colon cancer cells exposed to phenolic antioxidant ellagic acid. 1129 62

Insulin-like growth factor binding protein-3 (IGFBP-3), the major circulating carrier protein for IGFs, is also active in the cellular environment as a potent antiproliferative agent. It appears to function both by cell cycle blockade and the induction of apoptosis. Transfection of p53 negative T47D breast cancer cells to express IGFBP-3 leads to induction of the apoptotic protein bax and an increase in sensitivity to ionising radiation. IGFBP-3 can be transported to the nucleus by an importin beta mediated mechanism, where it has been shown to interact with the retinoid X receptor alpha and possibly other nuclear elements. Expression of oncogenic ras is associated with resistance to exogenous IGFBP-3, the effect being reversible by inhibition of mitogen activated protein (MAP) kinase phosphorylation. IGFBP-3 antiproliferative signalling appears to require an active transforming growth factor beta (TGF-beta) signalling pathway, and IGFBP-3 stimulates phosphorylation of the TGF-beta signalling intermediates Smad2 and Smad3. These recent findings all point to a complex intracellular mode of action of IGFBP-3, which will need to be better understood if anti-cancer treatments are to take advantage of the antiproliferative activity of IGFBP-3.
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PMID:Signalling pathways involved in antiproliferative effects of IGFBP-3: a review. 1137 25

The ability of insulin to protect neurons from apoptosis was examined in differentiated R28 cells, a neural cell line derived from the neonatal rat retina. Apoptosis was induced by serum deprivation, and the number of pyknotic cells was counted. p53 and Akt were examined by immunoblotting after serum deprivation and insulin treatment, and caspase-3 activation was examined by immunocytochemistry. Serum deprivation for 24 h caused approximately 20% of R28 cells to undergo apoptosis, detected by both pyknosis and activation of caspase-3. 10 nm insulin maximally reduced the amount of apoptosis with a similar potency as 1.3 nm (10 ng/ml) insulin-like growth factor 1, which acted as a positive control. Insulin induced serine phosphorylation of Akt, through the phosphatidylinositol (PI) 3-kinase pathway. Inhibition of PI 3-kinase with wortmannin or LY294002 blocked the ability of insulin to rescue the cells from apoptosis. SN50, a peptide inhibitor of NF-kappaB nuclear translocation, blocked the rescue effect of insulin, but neither insulin or serum deprivation induced phosphorylation of IkappaB. These results suggest that insulin is a survival factor for retinal neurons by activating the PI 3-kinase/Akt pathway and by reducing caspase-3 activation. The rescue effect of insulin does not appear to be mediated by NF-kappaB or p53. These data suggest that insulin provides trophic support for retinal neurons through a PI 3-kinase/Akt-dependent pathway.
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PMID:Insulin rescues retinal neurons from apoptosis by a phosphatidylinositol 3-kinase/Akt-mediated mechanism that reduces the activation of caspase-3. 1144 30

BH3-only proteins function at a proximal point in a conserved cell death pathway by binding, through their BH3 domains, to other Bcl-2 family members and triggering mitochondrial events associated with apoptosis. Here, we describe a strongly pro-apoptotic BH3-only protein, designated Bbc3, whose expression increases in response to diverse apoptotic stimuli. bbc3 mRNA levels were induced by exposure to DNA-damaging agents and by wild-type p53, which mediates DNA damage-induced apoptosis. p53 transactivated bbc3 through consensus p53 binding sites within the bbc3 promoter region, indicating that bbc3 is a direct target of p53. Additionally, bbc3 mRNA was induced by p53-independent apoptotic stimuli, including dexamethasone treatment of thymocytes, and serum deprivation of tumor cells. Insulin-like growth factor-1 and epidermal growth factor, growth factors with broad anti-apoptotic activity, were each sufficient to suppress Bbc3 expression in serum-starved tumor cells. These results suggest that the transcriptional regulation of bbc3 contributes to the transduction of diverse cell death and survival signals.
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PMID:Expression of bbc3, a pro-apoptotic BH3-only gene, is regulated by diverse cell death and survival signals. 1157 83

Insulin-like growth factor-1 (IGF-1) plays an important growth-promoting effect by activating the PI3K/Akt signalling pathway, inhibiting apoptotic pathways and mediating mitogenic actions. Tyrphostin AG 1024, one selective inhibitor of IGF-1R, was used to evaluate effects on proliferation, radiosensitivity, and radiation-induced cell apoptosis in a human breast cancer cell line MCF-7. Exposure to Tyrphostin AG 1024 inhibited proliferation and induced apoptosis in a time-dependent manner, and the degree of growth inhibition for IC20 plus irradiation (4 Gy) was up to 50% compared to the control. Examination of Tyrphostin AG 1024 effects on radiation response demonstrated a marked enhancement in radiosensitivity and amplification of radiation-induced apoptosis. Western blot analysis indicated that Tyrphostin AG 1024-induced apoptosis was associated with a downregulation of expression of phospho-Akt1, increased expression of Bax, p53 and p21, and a decreased expression of bcl-2 expression, especially when combined with irradiation. To our knowledge, this is the first report showing that an IGF-1 inhibitor was able to markedly increase the response of tumour cells to ionizing radiation. These results suggest that Tyrphostin AG 1024 could be used as a potential therapeutic agent in combination with irradiation.
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PMID:Tyrphostin AG 1024 modulates radiosensitivity in human breast cancer cells. 1174 48

Ethanol impairs insulin-stimulated survival and mitochondrial function in immature proliferating neuronal cells due to marked inhibition of downstream signaling through P13 kinase. The present study demonstrates that, in contrast to immature neuronal cells, the major adverse effect of chronic ethanol exposure (50 mM) in post-mitotic rat cerebellar granule neurons is to inhibit insulin-stimulated mitochondrial function (MTT activity, MitoTracker Red fluorescence, and cytochrome oxidase immunoreactivity). Ethanol-impaired mitochondrial function was associated with increased expression of the p53 and CD95 pro-apoptosis genes, reduced Calcein AM retention (a measure of membrane integrity), increased SYTOX Green and propidium iodide uptake (indices of membrane permeability), and increased oxidant production (dihydrorosamine fluorescence and H2O2 generation). The findings of reduced membrane integrity and mitochondrial function in short-term (24 h) ethanol-exposed neurons indicate that these adverse effects of ethanol can develop rapidly and do not require chronic neurotoxic injury. A role for caspase activation as a mediator of impaired mitochondrial function was demonstrated by the partial rescue observed in cells that were pre-treated with broad-spectrum caspase inhibitors. Finally, we obtained evidence that the inhibitory effects of ethanol on mitochondrial function and membrane integrity were greater in insulin-stimulated compared with nerve growth factor-stimulated cultures. These observations suggest that activation of insulin-independent signaling pathways, or the use of insulin sensitizer agents that enhance insulin signaling may help preserve viability and function in neurons injured by gestational exposure to ethanol.
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PMID:Ethanol impairs insulin-stimulated mitochondrial function in cerebellar granule neurons. 1176 90

Carcinogenesis involves a multistep process whereby a normal healthy cell undergoes both immortalization and oncogenesis to become fully transformed. Immortalization results from the subversion of critical cell cycle regulatory checkpoints, thereby allowing a cell to extend its finite life span and to maintain telomeric length. Oncogenesis is the manifestation of additional genetic events that are capable of conferring upon the cell an actual growth advantage. Such an advantage may relieve a cell of its normal requirements for a particular growth factor or may enhance the ability of a cell to proliferate outside of its normal microenvironment. To further investigate this multistep process, we developed an immortalized mammary epithelial cell line by overexpressing the catalytic subunit of telomerase (human telomerase reverse transcriptase) in primary human mammary epithelial cell lines. We present evidence that the overexpression of human telomerase reverse transcriptase was sufficient to extend the life span of the cells and allow for additional events that lead to immortalization. The result was the establishment of an IMEC line. Biochemical analysis of these cells indicates a basal epithelial phenotype with expression of high molecular weight cytokeratins. We show that continued growth of the IMECs is rigorously dependent upon both insulin and epidermal growth factor, and that the mitogenic effects of these factors on the IMECs are mediated in part by AKT. In addition, IMECs express the p53 family member DeltaN-p63-alpha, which is found in basal epithelial cells of many tissues and has been implicated as playing an essential role in normal epithelial development. Our studies suggest that the immortalization of basal epithelial cells of the mammary gland may be an early step in the initiation of a subset of breast cancers with a basal epithelial phenotype.
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PMID:Growth factor requirements and basal phenotype of an immortalized mammary epithelial cell line. 1178 64


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