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)

The hepatic stellate cell (HSC), the pericyte of the liver sinusoids belongs to the mesenchymal cells of the liver. Damaging noxae induce a transformation from the quiescent (vitamin A-storing cell) to the activated (connective tissue-producing cell) state. The balance between proapoptotic and surviving factors decides about the fate of the activated HSC. Interferon-alpha (IFN-alpha) has been shown to elicit antiproliferative and/or antifibrogenic effects in various cell types of mesenchymal origin. We therefore investigated the effect of IFN-alpha on primary cultured rat HSC in their quiescent (day 2) and activated state (day 7). IFN-alpha significantly inhibited spontaneous apoptosis in activated HSC in vitro and simultaneously inhibited cell cycle progression by inducing a G1 arrest. The effect of IFN-a is not accompanied by a modulation of CD95, CD95L, p53, p21(WAF1), p27, bcl-2, bcl-xL, bax, NFkappaB, or IkappaB gene expression. Surprisingly, the IFN-alpha effect could be abolished completely by blocking JAK2 activity or JAK2 translation. The downregulating effect of IFN-alpha on the activity of caspase-8 and caspase-3 could also be neutralized using tyrphostin AG490 or JAK-2 antisense. Taken together IFN-alpha inhibits apoptosis of activated HSC by activation of JAK2 which inhibits the caspase-8 apoptosis pathway.
 ...
PMID:Antiapoptotic effect of interferon-alpha on hepatic stellate cells (HSC): a novel pathway of IFN-alpha signal transduction via Janus kinase 2 (JAK2) and caspase-8. 1260 46

The p53 tumor-suppressor plays a critical role in the prevention of human cancer. In the absence of cellular stress, the p53 protein is maintained at low steady-state levels and exerts very little, if any, effect on cell fate. However, in response to various types of stress, p53 becomes activated; this is reflected in elevated protein levels, as well as augmented biochemical capabilities. As a consequence of p53 activation, cells can undergo marked phenotypic changes, ranging from increased DNA repair to senescence and apoptosis. This review deals with the mechanisms that underlie the apoptotic activities of p53, as well as the complex interactions between p53 and central regulatory signaling networks. In p53-mediated apoptosis, the major role is played by the ability of p53 to transactivate specific target genes. The choice of particular subsets of target genes, dictated by covalent p53 modifications and protein-protein interactions, can make the difference between life and apoptotic death of a cell. In addition, transcriptional repression of antiapoptotic genes, as well as transcription-independent activities of p53, can also contribute to the apoptotic effects of p53. Regarding the crosstalk between p53 and signaling networks, this review focuses on the interplay between p53 and two pivotal regulatory proteins: beta-catenin and Akt/PKB. Both proteins can regulate p53 as well as be regulated by it. In addition, p53 interacts with the GSK-3beta kinase, which serves as a link between Akt and beta-catenin. This review discusses how the functional balance between these different interactions might dictate the likelihood of a given cell to become cancerous or be eliminated from the replicative pool, resulting in suppression of cancer.
 ...
PMID:Decision making by p53: life, death and cancer. 1271 14

Activated Notch1 (AcN1) alleles cooperate with oncogenes from DNA tumor viruses in transformation of epithelial cells. AcN1 signaling has pleiotropic effects, and suggested oncogenic roles include driving proliferation through cyclin D1 or the generation of resistance to apoptosis on matrix withdrawal through a phosphatidylinositol 3-kinase (PI3K)-PKB/Akt-dependent pathway. Here, we extend the antiapoptotic role for AcN1 by showing inhibition of p53-induced apoptosis and transactivation. Chemical inhibitors of the PI3K pathway block AcN1-induced inhibition of p53-dependent apoptosis and nuclear localization of Hdm2. We show that expression of wild-type p53 does not inhibit synergistic transformation by AcN1 and human papillomavirus E6 and E7 oncogenes. We suggest that activation of Notch signaling may serve as an additional mechanism to inhibit wild-type p53 function in papillomavirus-associated neoplasia.
 ...
PMID:Activated Notch1 inhibits p53-induced apoptosis and sustains transformation by human papillomavirus type 16 E6 and E7 oncogenes through a PI3K-PKB/Akt-dependent pathway. 1276 30

Human malignant gliomas arise from neural progenitor cells and/or dedifferentiated astrocytes. By now, they are genetically so well characterized that several murine glioma models have emerged that faithfully reiterate the typical histological features of the disease. In experimental animals, only one or two elements of the growth factor/Ras, PI3K/PTEN/PKB, p53/ARF/HDM2, and p16/Rb/cyclinD/CDK4 pathways are targeted. In human gliomas, many additional genes and pathways are targeted due to a most severe mutator phenotype that leads to the accumulation of countless epigenetic and genetic alterations. Changes that convey a growth advantage are selected for, leading to overgrowth of precursor cell populations with increasingly malignant tumor cell clones. While murine models represent a powerful tool for elucidating the role of genetic pathways, mechanisms of response and resistance to new therapeutic agents might be fundamentally different due to the high degree of genomic instability in the human disease. In fact, little is known about the molecular causes of genomic instability involved in gliomas, except for the rare Turcot's syndrome, O(6)-methylguanine-DNA methyltransferase, and the apurinic/apyrimidinic endonuclease Ape-1. Novel approaches that selectively exploit fundamental metabolic differences between tumor and normal cells have to consider these fundamental differences between human disease and presently available, highly sophisticated animal models.
 ...
PMID:Genes and pathways driving glioblastomas in humans and murine disease models. 1278 72

As part of an extensive multi-institutional DIANAIDS study focused on assessing the risk factors, natural history, diagnosis and follow-up of genital human papillomavirus (HPV) infections in HIV-infected women, the present communication reports a sub-cohort of 142 women (89 HIV+ and 48 HIV-), followed-up for a mean of 14.07 (+/-10.84) months to analyse the factors predicting the persistence and clearance of HPV infections (polymerase chain reaction [PCR] and sequencing) and cervical Papanicolaou (PAP) smear abnormalities, using both univariate (Kaplan-Meier) and multivariate (Cox) survival analysis. The appearance of new HPV infections during the follow-up was significantly more frequent in HIV-positive than in HIV-negative women, odds ratio (OR) 8.800 (95% confidence interval [CI]: 1.199-64.611), and also the clearance rate was significantly less frequent in HIV-positive than in HIV-negative women, 69.2% vs 22.8%, respectively (OR 0.330; 95% CI: 0.163-0.670). These two groups were also markedly different with respect to the clinical course of the cervical lesions, in the frequency of progressive disease (determined by PAP smear) was higher in HIV-positive group (12/89) than in HIV-negative women (2/52) (OR 3.506; 95% CI 0.816-15.055) (P = 0.055), in whom the disease regressed more frequently than in HIV-positive women (13.5% vs 7.9%) (OR 0.584; 95% CI 0.217-1.573). Using (1) HPV-positivity, (2) oncogenic HPV-type and (3) significant PAP smear abnormality at the end of follow-up as outcome measures, (1) was significantly (P < 0.001) predicted by the following variables in univariate analysis: age, mode of contraception, CD4 count, and HIV-positivity. The significant predictors of (2) were age and mode of contraception. The outcome measure (3) was significantly predicted by CD4 count, PAP smear abnormality and PCR status at entry. In the multivariate analysis, the significant independent predictive factors for HPV-positivity proved to be only the HIV status (P < 0.001), and PCR status at entry, p53 polymorphism at aa-72, oncogenic HPV type and significant PAP smear at entry remained independent predictors, with the significance level of P < 0.05. None of the significant predictors of oncogenic HPV type in univariate analysis retained their independent value in multivariate analysis. Oncogenic HPV type at entry proved to be an independent predictor of significant PAP smear (P < 0.05). The present results indicate that HIV-infected women, even on highly active antiretroviral therapy, demonstrate a more aggressive clinical course of cervical HPV infections, and fail to eradicate the disease more frequently than HIV-negative women. This persistence of HPV-positivity, oncogenic HPV type and significant PAP smear abnormality can be predicted by the results of PAP test and HPV typing in univariate analyses, and partly retain their independent predictive value also in multivariate analysis. Clearly, in addition to regular monitoring by PAP smear, HPV testing for the oncogenic HPV types seems to provide additional prognostic information in the management of cervical lesions in HIV-infected women.
Int J STD AIDS 2003 Jun
PMID:Factors predicting the persistence of genital human papillomavirus infections and PAP smear abnormality in HIV-positive and HIV-negative women during prospective follow-up. 1281 71

Sodium salicylate is known to induce apoptosis in a variety of cancer cells. However, the molecular mechanism for salicylate-induced apoptosis is yet unclear. Here we show that in HCT116 colon carcinoma cells, 10 mM sodium salicylate induces caspase-3 activation and degradation of its substrates, poly(ADP-ribose) polymerase (PARP), beta-catenin, and retinoblastoma (Rb). In contrast, sodium salicylate did not exert any significant effects on the expression of Fas L that is implicated in extrinsic apoptotic pathway and the levels of Bcl-2 family proteins, Bcl-2, Bcl-xsl, and Bad, which are involved in intrinsic apoptotic pathway, and anti-apoptotic molecules, c-IAP1 and HSP73. In addition, 10 mM salicylate induced p53 tumor suppressor protein that plays an important role in cell cycle arrest or apoptosis and the induction seemed to be linked to its phosphorylation at Set 15. To investigate the signal pathways for salicylate-induced apoptosis, we examined the effects of sodium salicylate on protein kinase activities. Sodium salicylate activated p38MAPK through phosphorylation at Thr 180/Tyr 182 and Akt/PKB at Ser 473, whereas it partially activated ERK1/2 through its phosphorylation at Thr 202/Tyr 204. We also show that SB203580 (a specific p38MAPK inhibitor), but not other protein kinase inhibitors (PD98059, LY294002, and wortmannin), significantly prevented salicylate-induced apoptosis. These results suggest that sodium salicylate-induced apoptosis in HCT116 colorectal cancer cells is mediated by p38MAPK.
 ...
PMID:Sodium salicylate induces apoptosis in HCT116 colorectal cancer cells through activation of p38MAPK. 1285 2

We demonstrated that enhancement of X-ray-induced apoptosis/rapid cell death by wortmannin accompanied by increased activation of JNK/SAPK in human leukemia MOLT-4 cells. Rapid cell death/apoptosis was determined either by the dye exclusion test or by the appearance of Annexin V-positive cells and cleaved PARP fragments. Enhancement was observed only at higher concentrations of wortmannin, i.e. 1 microM or more. At these high concentrations, both DNA-PK and ATM were inhibited. X-ray-induced phosphorylation of Ser 15 of p53/TP53, accumulation of both p53/TP53 and p21/WAF1/CDKN1A, and phosphorylation of XRCC4 were all suppressed. The enhancement of apoptosis/rapid cell death by wortmannin was prevented by addition of caspase inhibitors, Z-VAD-FMK or Ac-DEVD-CHO, or by transfection and overexpression of mouse Bcl2, which is known as an anti-apoptosis protein. The requirement for a high concentration of wortmannin, i.e. 1 microM or more, indicates that inhibition of both DNA-PK and ATM was necessary for the enhanced apoptosis/rapid cell death. Phosphorylation of AKT/PKB was completely suppressed at a much lower concentration, i.e. 0.1 microM wortmannin, where no enhancement of X-ray-induced apoptosis/rapid cell death was observed. On the other hand, X-ray-induced phosphorylation of JNK and its kinase activity as well as apoptosis/rapid cell death were all significantly enhanced only at high concentrations of wortmannin, i.e. 1 microM or more. Furthermore, the extent of enhancement of both JNK phosphorylation and of apoptosis/rapid cell death by wortmannin was less in Rh1a cells, which are ceramide- and radiation-resistant variant cells compared to the parental MOLT-4 cells. Therefore, activation of the JNK pathway was considered important for the enhancement of X-ray-induced apoptosis/rapid cell death of MOLT-4 cells by wortmannin, because of the requirement for a higher concentration of wortmannin than that required for inhibition of AKT phosphorylation. The suppression of the AKT-dependent pathway by wortmannin may have some underlying role in activating the JNK pathway toward the enhancement of cell death in the current system.
 ...
PMID:Wortmannin-enhanced X-ray-induced apoptosis of human T-cell leukemia MOLT-4 cells possibly through the JNK/SAPK pathway. 1296 28

The ability of the focal adhesion kinase (FAK) to integrate signals from extracellular matrix and growth factor receptors requires the integrity of Tyr397, a major autophosphorylation site that mediates the Src homology 2-dependent binding of Src family kinases. However, the precise roles played by FAK in specific Src-induced pathways, especially as they relate to oncogenic transformation, remain unclear. Here, we investigate the role of FAK in v-Src-induced oncogenic transformation by transducing temperature-sensitive v-Src (ts72v-Src) into p53-null FAK+/+ or FAK-/- mouse embryo fibroblasts (MEF). At the permissive temperature (PT), ts72v-Src induced abundant tyrosine phosphorylation, morphological transformation and cytoskeletal rearrangement in FAK-/- MEF, including the restoration of cell polarity, typical focal adhesion complexes, and longitudinal F-actin stress fibers. v-Src rescued the haptotactic, linear directional, and invasive motility defects of FAK-/- cells to levels found in FAK+/+ or FAK+/+-[ts72v-Src] cells, and, in the case of monolayer wound healing motility, there was an enhancement. Src activation failed to increase the high basal tyrosine phosphorylation of the Crk-associated substrate, CAS, found in FAK-/- MEF, indicating that CAS phosphorylation alone is insufficient to induce motility in the absence of FAK- or v-Src-induced cytoskeletal remodeling. Compared with FAK+/+[ts72v-Src] controls, FAK-/-[ts72v-Src] clones exhibited 7-10-fold higher anchorage-independent proliferation that could not be attributed to variations in either v-Src protein level or stability. Re-expression of FAK diminished the colony-forming activities of FAK-/-[ts72v-Src] without altering ts72v-Src expression levels, suggesting that FAK attenuates Src-induced anchorage independence. Our data also indicate that the enhanced Pyk2 level found in FAK-/- MEF plays no role in v-Src-induced anchorage independence. Overall, our data indicate that FAK, although dispensable, attenuates v-Src-induced oncogenic transformation by modulating distinct signaling and cytoskeletal pathways.
 ...
PMID:v-Src rescues actin-based cytoskeletal architecture and cell motility and induces enhanced anchorage independence during oncogenic transformation of focal adhesion kinase-null fibroblasts. 1450 Jul 22

In this study, we examined the cellular and molecular responses of fibroblasts cultured on a polyelectrolyte complex (PEC) derived from sulfated chitin as a polyanion and chitosan as a polycation. On PEC-coated dishes, the fibroblasts aggregated and then developed spheroid-like structures. At earlier stages of culture, DNA synthesis of cells cultured on PEC was stimulated approximately 75% higher than control cells. Among various signaling molecules examined, including mitogen-activated protein kinases, Akt/PKB and p53, an extracellular-signal-regulated kinase (ERK) was selectively and constitutively phosphorylated in cells cultured on PEC. The constitutive phosphorylation of ERK was derived from an activation of the ERK kinase MEK, but not from an inactivation of the ERK phosphatase MKP-1. Furthermore, ERK phosphorylation was almost abolished by a membrane receptor tyrosine kinase inhibitor. The enhanced phosphorylation of focal adhesion kinase, a downstream molecule of integrins, was also observed in cells cultured on PEC. These results suggest that fibroblasts recognize PEC as a continuous mitogenic stimulant which results in the constitutive activation of the MEK-ERK pathway toward mitogenesis. Further, PEC interacts with the cell membrane leading to activation of membrane molecules, including integrins and receptor tyrosine kinases. These responses may account, at least in part, for the potential use of PEC as a biomaterial for tissue regeneration.
 ...
PMID:Enhanced DNA synthesis accompanied by constitutive phosphorylation of the ERK pathway in human fibroblasts cultured on a polyelectrolyte complex. 1453 74

Glucocorticoids (GC) such as hydrocortisone and dexamethasone (DEX) protect steroidogenic granulosa cells against apoptosis induced by serum deprivation, cAMP, tumor necrosis factor alpha stimulation or p53 activation. The protective effects were evident both in primary rat and human granulosa cells, which comprise the main population of the ovarian follicular cells, as well as in steroidogenic granulosa cell lines established in our laboratory. A correlation between the expression of Bcl-2 protein and protection against apoptosis induced by DEX was found in granulosa cell lines expressing various levels of Bcl-2. Incubation with DEX leads to development of a rigid network of actin cytoskeleton and increased incidence of adherence and gap junctions. Higher content of connexin 43 and total cadherins were found in GC stimulated cells compared to non-stimulated, suggesting that cell contact and intracellular communication contribute to the DEX induced resistance to apoptotic signals. Activation by DEX of MAPK and Akt/PKB but not p38 supported the view of a pleiotropic action of GC against apoptotic signals. Granzyme B, a protease characteristic for induction of apoptosis by T-cytotoxic lymphocytes and natural killer cells, was expressed and augmented during stimulation of apoptosis in the granulosa cells, and its synthesis and activation was blocked by DEX. It is concluded that GC exerted their anti-apoptotic effects in granulosa cells by multiple characteristic pathways. Moreover, the presence of endogenous granzyme B in granulosa cells suggest a novel intrinsic alternative apoptotic pathway that was earlier reported to be mediated uniquely by T-cytotoxic lymphocytes and natural killer cells. The anti-apoptotic effect of GC may play an important role in the healing process of the ovulatory follicle subsequent to follicular rupture and its rapid conversion to an active corpus luteum.
 ...
PMID:Pleiotropic anti-apoptotic activity of glucocorticoids in ovarian follicular cells. 1455 13


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>