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)

Several reports have appeared on the use of combined radioimmunotherapy (RAIT) and chemotherapy. The choice of drug to use with RAIT and how to space the two treatments has not been completely addressed. Because every patient's cancer presents with a specific molecular phenotype, we hypothesized that it may be necessary to tailor therapy based on specific gene expression. We addressed how the form of expression of a single gene, the p53 tumor suppressor, would impact the choice of agents, as well as sequence and spacing of agents. p53 regulates cell cycle arrest to allow for DNA repair after therapy-induced small DNA damage or induction of apoptosis if damage is great and has been shown to affect chemo- and radiosensitivity of cancer cells. We established 3 stable p53 transfectants of the SKOV-3 p53null parental line (p53(wt), p53(143mut) or p53(273mut)). p53 expression was confirmed using flow cytometry, using the DO1 pan-p53 Ab and the PAb240 anti-p53mut Ab. The colorimetric MTT assay was then used to measure dose-dependent growth inhibition from single modality chemotherapy (doxorubicin, carboplatin, paclitaxel or topotecan) or radioimmunotherapy (90Y-RS-7 IgG anti-EGP1). The % survival vs. log [drug] were plotted to obtain the IC50. We then used a matrix design in which we varied the sequence of the first and second modality of treatment and the spacing between the 2 treatments to determine the most synergistic and antagonistic combinations for the parental SKOV-3 and each of the 3 transfectants. The IC50 for each therapeutic agent varied as a function of the form of p53 expressed. For example, of the 4 lines, the p53wt transfectant was the most resistant to topotecan and the 143mut was the most resistant to carboplatin. The 273mut was quite sensitive to both doxorubicin and paclitaxel, whereas the p53null and wt were not. For multimodal treatments, most combinations of RAIT and chemotherapy resulted in a 30-40% growth inhibition (GI) and were either additive or moderately antagonistic. The 3 best (>60% GI) and 3 worst (<25% GI) combinations were identified and were unique to the parental p53null and to the 3 transfectants. Certain combinations showed clear synergy and others were antagonistic, with the first treatment modality blocking the growth inhibitory effects of the second treatment modality. The form of p53 expressed affects chemosensitivity and radiosensitivity and will influence optimal multimodal therapy with RAIT and chemotherapy and the dose-schedule (sequential with RAIT first or with drug first) when more than 1 agent is used.
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PMID:An in vitro model to optimize dose scheduling of multimodal radioimmunotherapy and chemotherapy: effects of p53 expression. 1463 18

This work analyzes the effectiveness of wortmannin in boosting the lethality induced by different doses of X-rays, using the colorimetric assay of MTT. Bladder tumoral cell lines differing in radiosensitivity and p53 status were used. Since wortmannin is able to inhibit DNA-dependent protein kinase (DNA-PK) and rejoining of double-strand breaks (DSBs), we have analyzed the constitutive contents and expression after irradiation of the catalytic subunit of DNA-PK (DNA-PKcs) in our cell lines with the aim of explaining the differential effect of wortmannin as radiosensitizer. Considering that DNA-PK is the main protein complex involved in DNA DSB repair, the ability to remove DSBs after irradiation (with or without wortmannin) was evaluated in the different cell lines by the use of pulse-field gel electrophoresis. Our results indicate a higher radiosensitization in the radio-resistant cell line that shows both high constitutive contents of DNA-PKcs and a high rate of DNA repair by the fast component. In contrast, no radiosensitizer effect of wortmannin was observed in the radiosensitive cell line, previously characterized as defective in DSB repair by a low repair fidelity, and - as our results show - with low constitutive contents and later post-irradiation expression of DNA-PKcs. No clear effect related to p53 status of the cell line was observed. These results suggest that high constitutive contents of DNA-PKcs are indicative of radio-resistant phenotypes, and analysis of the expression of this protein could be helpful in the optimal establishment of wortmannin as radiosensitizer in bladder tumoral cell lines.
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PMID:Radiosensitizer effect of wortmannin in radioresistant bladder tumoral cell lines. 1465 54

Arsenic is a naturally occurring element, but anthropogenic activities can lead to a substantial contamination of the environment. Exposure to arsenic has been associated with a significant number of adverse health effects in humans including: cardiovascular disease, diabetes, hearing loss, developmental abnormalities, anemia, neurologic and neurobehavioral disorder, leukopenia, eosinophilia, fibrosis of the liver and the kidney and various neoplasms. However, the cellular and molecular events associated with arsenic toxicity are poorly understood. Also, the precise mechanisms by which arsenic acts as a carcinogen in humans remain to be elucidated. In the present study, we used human liver carcinoma (HepG2) cells as a model to study the molecular mechanisms of arsenic-induced toxicity and carcinogenesis. We hypothesized that arsenic-induced expression of stress genes and related proteins may play a role in the cellular and molecular events leading to toxicity and tumorigenesis in liver cells. To test this hypothesis, we performed the MTT-assay for cell viability, the CAT-Tox (L) assay for gene induction, and the Western Blot analysis to assess the expression of cellular proteins including c-fos, HMTIIA, HSP70 and p53. Data obtained from the MTT assay indicated a strong dose-response relationship with respect to arsenic trioxide toxicity. Upon 48 hr of exposure, the chemical dose required to cause 50% reduction in cell viability (LD50) was computed to be 8.55 +/- 0.58 microg/ml. The CAT-Tox (L) assay showed statistically significant inductions (p<0.05) of c-fos, HMTIIA, and HSP70. Western blot analysis also demonstrated a dose-response relationship with regard to expression of specific cellular proteins. The p53 protein was expressed in arsenic trioxide-treated cells, however, the densitometric analysis did not show any significant differences (p<0.05) between treated and control cells. The lack of a significant induction of p53 may be due to the potential mitogenic effect of arsenic at low levels of arsenic exposure.
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PMID:Arsenic trioxide-induced transcriptional activation of stress genes and expression of related proteins in human liver carcinoma cells (HepG2). 1468 89

Cis-diaminechloro-[2-(diethylamino) ethyl 4-amino-benzoate, N(4)]-chloride platinum (II) monohydrochloride monohydrate (DPR) is a new platinum triamine complex obtained from the synthesis of cisplatin and procaine. In this paper we analyzed, adopting a disease-oriented strategy, the tumour selectivity of this compound, its ability to induce apoptosis and its mechanism of interaction with DNA. The inhibition of cell proliferation was evaluated by the MTT assay using a panel of 51 tumour cell lines. Some of them were also evaluated for the induction of apoptosis by 4'-6-diamidine-2'-phenylindole (DAPI) staining, Western blot of p53 protein and agarose gel electrophoresis of ladder DNA. Finally, interstand cross-links (ISCL) were evaluated by ethidium bromide fluorescence technique. When evaluated by the MTT assay, DPR showed a high selective activity for neuroblastoma, small cell lung cancer (SCLC), ovarian cancer and leukemia cell lines. The comparison of mean graphs of DPR and cisplatin suggested that our compound possesses a mechanism of action similar to that, at least in part, of its parent compound. Moreover, DPR showed itself to be a good trigger of programmed cell death, as demonstrated by DAPI staining, activation of p53 protein and agarose gel electrophoresis of ladder DNA. Finally, the study of the formation of ISCLs demonstrated that DPR, despite being a monofunctional platinum compound, is able to form bifunctional adducts through the release of procaine residue. Data presented here suggest that DPR is an antitumour agent able to trigger apoptosis, and that it is endowed with a peculiar mechanism(s) of action and a special selective activity against two tumours, namely neuroblastoma and SCLC, which are still characterized by a low incidence of long-term survivors.
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PMID:Inhibition of cell growth, induction of apoptosis and mechanism of action of the novel platinum compound cis-diaminechloro-[2-(diethylamino) ethyl 4-amino-benzoate, N(4)]-chloride platinum (II) monohydrochloride monohydrate. 1470 90

Amyloid beta-peptide (Abeta) contributes to the pathogenesis of Alzheimer's disease (AD), causing neuronal death through apoptosis. In this study, the neuroprotective role of small peptides, Gly-Pro-Glu (GPE), Gly-Glu (GE), Gly-Pro-Asp (GPD), and Gly-Pro-Arg (GPR) were examined against Abeta-induced toxicity in cultured rat hippocampal neurons. We report here that GPR (10-100 microM) prevented Abeta-mediated increase in lactate dehydrogenase (LDH) release and Abeta inhibition of MTT reduction, even in neurons that were pre-exposed to Abeta for 24 or 48 h. Since GPR prevented Abeta inhibition of MTT reduction, the anti-apoptotic effect of GPR was studied by examining activation of caspase-3 and expression of p53 protein. Caspase-3 was significantly activated by 20 microM Abeta25-35 and 5 microM Abeta1-40, but GPR effectively prevented the Abeta-mediated activation of caspase-3. Similarly, Abeta increased numbers of p53-positive cells, but GPR prevented this Abeta effect. Our findings suggest that GPR can rescue cultured rat hippocampal neurons from Abeta-induced neuronal death by inhibiting caspase-3/p53-dependent apoptosis.
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PMID:A three amino acid peptide, Gly-Pro-Arg, protects and rescues cell death induced by amyloid beta-peptide. 1476 84

Lissoclinolide is a small non-nitrogenous lactone isolated from the marine ascidian Lissoclinum patella. Previous studies of lissoclinolide (isolated from a fungus and an actinomycete) have identified varying activity against both Gram-negative and Gram-positive bacteria. In this study, lissoclinolide was able to inhibit cell growth in various mammalian tumor lines at an average IC(50) of 395 nM (determined by MTT conversion after 48-h treatment). Treatment of HCT 116 human colon tumor cells with 2.4 microM lissoclinolide resulted in a strong arrest in the G(2)/M phase of the cell cycle after 24-h exposure. A daughter cell line lacking p53 showed an identical response while there was a slight increase in cytotoxicity towards a p21 null cell line. Although treatment with 2.4 microM lissoclinolide did not result in apoptosis after 48 h, this arrest was not reversible when drug wash out was attempted. The mechanism of action does not appear to involve tubulin, ubiquitin-specific isopeptidases, p53 or p21. COMPARE analysis in the NCI 60 cell line tumor panel revealed a moderate selectivity towards colon tumor cell lines.
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PMID:A profile of the in vitro antitumor activity of lissoclinolide. 1496 5

Photodynamic therapy (PDT) is an effective local cancer treatment that induces cytotoxicity through the intracellular generation of reactive oxygen species. It is generally thought that p53 regulates chemotherapy and radiation therapy responsiveness via apoptosis induction control. The current study investigated whether cellular sensitivity to PDT is increased when a wild-type (wt) p53 status is restored by gene transfer in the established HT9blk Ala273-mutant p53 human colon cancer cell line. The photosensitizer accumulation was similar in both cell lines, and survival measurements using MTT test and clonogenic assays demonstrated that wt p53 transfected cells (HT29A4) were significantly more sensitive to chlorin e6-mediated PDT. P53 protein expression and its functionality as a transcription factor demonstrated through the induction of mdm2 transactivation, were not found to be directly involved in this differential photosensitivity. However, induction of caspase 3 activation (2.6-fold), leading to significant apoptosis induction 24-h after PDT was observed in HT29A4 cells. These results suggest that the introduction of wt p53 in HT29A4 potentiates the cell sensitivity to PDT through the induction of apoptosis in relation to p53 mutational status, but independently of p53 expression level and transcriptional activity.
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PMID:Wild-type p53 gene transfer into mutated p53 HT29 cells improves sensitivity to photodynamic therapy via induction of apoptosis. 1501 Aug 35

Somatostatin receptors (SSTRs) have been detected in many normal and malignant tissues. This wide expression has been used for diagnostic, prognostic and therapeutic purposes. Five SSTR subtypes (SSTR 1-5) have been identified whose activation is responsible for the signal transduction through many different intracellular pathways. In the present study the expression of SSTR mRNA was determined by reverse-transcriptase (RT)-PCR in 42 meningiomas. About 88% of the tumors analyzed (37/42) were positive for at least one of the five SSTR subtypes displaying a variable pattern of expression of the different SSTR subtypes. SSTRI and SSTR2 were the most frequently mRNA detected (69% and 79% of the sample analyzed, respectively). The other subtypes were found in the 43%, 33% and 33% of cases for SSTR3, SSTR4 and SSTR5, respectively. In 22, out of 42 patients (52%) three or more SSTRs were detected. The expression of the different SSTR subtypes did not correlate with the expression of bcl-2 (apoptosis-associated protein) and MIB-1 (a proliferation marker), assessed by immunohistochemistry in a series of 34 tumor samples, while a correlation between the expression of SSTR3 and p53 was observed (p = 0.08). To evaluate a possible role of SSTR in the control of human meningioma cell proliferation, seven primary cell cultures obtained from fresh meningioma surgical tissues, were analyzed for their proliferative behavior by MTT assay and for their response to SST by [3H]-thymidine incorporation. In four out of six tumors (in one case no SSTR were detected) the treatment with SST caused a significant inhibition of DNA synthesis induced by the tumor-promoter phorbol myristate acetate. The evidence of the expression of SSTRs, mainly of SSTR2, in this series of specimens we analyzed altogether with in vitro antiproliferative effects of SST may open interesting perspectives for the diagnosis and the therapy of meningiomas.
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PMID:Expression of somatostatin receptor mRNA in human meningiomas and their implication in in vitro antiproliferative activity. 1501 81

The effects of the immunomodulation and antitumor metastasis of the Chinese medicinal fungus water extract (FWE) were investigated. After B16 melanoma cells were implanted in C57BL/6 mice through their tail veins, the mice were orally administered by FWE at low dose (160 mg/kg/day) and high dose (400 mg/kg/day) for 14 days. The tumor metastatic foci on the lung surface were observed under dissecting microscope. Phagocytosis of peritoneal macrophages was detected through ingesting chicken red blood cells (CRBC) test. Lymphocyte proliferation and the natural killer (NK) cell activity were determined by MTT method and lactate-dehydrogenase (LDH)-release assay, respectively. The expressions of bcl-2 and p53 of livers and lungs were assayed by immunohistochemical method. The results showed that FWE could increase body weights of mice dose dependently. The lung metastasis inhibition rates (MIR) of B16 melanoma cells by low dose and high dose of FWE were 15.5% and 72.7%, respectively. FWE at the two doses enhanced significantly (p<0.05) the phagocytosis, which was evaluated using the phagocytic rate (PR) and phagocytic index (PI). FWE had significantly promoted mice' NK activity at high dose (p<0.001). Lymphocyte proliferation was not significantly elevated in both of low- and high-dose groups. FWE depressed the levels of bcl-2 and p53 protein in the liver and lung cells at both of the two doses. These results indicate that FWE not only promoted the mouse's immunity, but also inhibited tumor metastasis.
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PMID:Effects of Chinese medicinal fungus water extract on tumor metastasis and some parameters of immune function. 1503 23

To evaluate anti-tumor effects of recombinant adenovirus p53, time-course p53, E6 expression, and cell growth inhibition were investigated in vitro and in vivo using cervical cancer cell lines such as CaSki, SiHa, HeLa, HeLaS3, C33A, and HT3. The cell growth inhibition was studied via cell count assay, MTT assay and neutral red assay. After transfecting AdCMVp53 into SiHa cells-xenografted nude mice, the transduction efficiency and anti-tumor effect were investigated for a month. The results showed that adenoviral p53 expression induced significant growth suppression on the cancer cells, in which E6 transcript was strongly repressed, and that the expression of p53 and E6 were remarkably dependent on each cell type. The transduction efficiency was highly maintained in vivo as well as in vitro, and the size of tumor was remarkably decreased in comparison with AdCMVLacZ control. The results suggest that the adenovirus-mediated p53 gene transfection was done very effectively in vitro and in vivo experiment, and the cell growth was suppressed via p53-dependent apoptotic cell death, and that the anti-tumor effect could be related to E6 and p53 expression pattern.
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PMID:Anti-cancer effect of adenovirus p53 on human cervical cancer cell growth in vitro and in vivo. 1508 33


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