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 aim of the present study was to evaluate the tumor suppressor genes p53, p21 WAF1/CIP1 and p27 KIP1 expression in astrocytic tumors, correlating the findings with the histopathological grade (WHO). An immunohistochemical study of the p53, p21 and p27 proteins using the streptavidin-biotin-peroxidase method was performed in fifty-five astrocytomas (13 grade I, 14 grade II, 7 grade III and 21 grade IV) and five samples of non-tumor brain tissue (negative control). p53 positive indices (PI) and labeling indices (LI) showed tendency to increase according to malignant progression. The nuclear expression of p27 presented similar inclination, except for the PI reduction verified in grade IV tumors. Otherwise, the cytoplasmic p27 staining was more evident between high-grade tumors (III and IV). p53 and nuclear p27 expression was correlated with the histological classification (p<0.01; test H). On the other hand, p21 indices revealed a propensity to reduction in agreement with malignant evolution of the astrocytic tumors, except for high scores observed in grade IV tumors. The non-tumor samples did not show any expression of these proteins. These results indicated the p53 mutation as an initial, relevant and potentially predictor of tumor progression event in astrocytomas, with the detection of p21 protein as an important resource for the deduction of functional situation of this gene. Moreover, the activation of p27 KIP1 was preserved in the astrocytic tumors and its cytoplasmic manifestation seems to be resultant of its nuclear expression, not demonstrating a direct impact in astrocytomas tumorigenesis.
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PMID:Immunoexpression of tumor suppressor genes p53, p21 WAF1/CIP1 and p27 KIP1 in humam astrocystic tumors. 1834 13

We previously reported that HS-1200, a synthetic chenodeoxycholic acid derivative, has apoptosis-inducing activity in various human cancer cells. The present study was undertaken to examine whether HS-1200 had an anticancer effect on HepG2 (wild-type p53) and Hep3B (p53 deleted) human hepatoma cells. Treatment of both cells with HS-1200 resulted in growth inhibition and induction of apoptosis as measured by MTT assay, nuclear staining, DNA fragmentation and flow cytometry analysis. The increase in apoptosis was associated with the alteration in the ratio of Bcl-2/Bax protein expression. In addition, flow cytometry analysis indicated that HS-1200 induced G1 phase arrest in both cells. When analyzing the expression of cell cycle-related proteins, we found that HS-1200 reduced the expression levels of cyclin D1, cyclin A, and Cdk2. HS-1200 treatment also caused an increase in the expression levels of p21 WAF1/CIP1 in HepG2 cells in a p53-dependent manner and in Hep3B cells in a p53-independent manner. Moreover, the expression level of p27 KIP1 was increased in both cell lines. We also observed that HS-1200 decreased the levels of cyclooxygenase (COX)-2 mRNA and protein expression. Furthermore, HS-1200 treatment markedly induced the Egr-1 expression at an early time point, and the increased expression levels of p53, p21 WAF1/CIP1, p27 KIP1, and COX-2 after treatment with HS-1200 were completely inhibited in HepG2 cells and partially inhibited in Hep3B cells by silencing of Egr-1, respectively. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anticancer activity of the synthetic bile acid derivative, HS-1200, through Egr-1 regulation.
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PMID:A chenodeoxycholic derivative, HS-1200, induces apoptosis and cell cycle modulation via Egr-1 gene expression control on human hepatoma cells. 1855 81

Expression levels of intact tumor suppressor proteins and molecular targets of anti-neoplastic agents are critical in defining cancer cell drug sensitivity; however, the intracellular location of a specific protein may be as important. Many tumor suppressor proteins must be present in the cell nucleus to perform their policing activities or for the cell to respond to chemotherapeutic agents. Nuclear proteins needed to prevent cancer initiation or progression or to optimize chemotherapeutic response include the tumor suppressor proteins p53, APC/beta-catenin, and FOXO family genes; negative regulators of cell cycle progression and survival such as p21(CIP1) and p27(KIP1;) and chemotherapeutic targets such as DNA topoisomerases I and IIalpha. Mislocalization of a nuclear protein into the cytoplasm can render it ineffective as a tumor suppressor or as a target for chemotherapy. Blocking nuclear export of any or all of these proteins may restore tumor suppression or apoptosis or, for topoisomerases I and IIalpha, reverse drug resistance to inhibitors of these enzymes. During disease progression or in response to the tumor environment, cancer cells appear to acquire intracellular mechanisms to export anti-cancer nuclear proteins. These mechanisms generally involve modification of nuclear proteins, causing the proteins to reveal leucine-rich nuclear export signal protein sequences. Subsequent export is mediated by CRM1. This review defines the general processes involved in nuclear export mediated by CRM1/RanGTP (exportin/XPO1), examines the functions of individual tumor suppressor nuclear proteins and nuclear targets of chemotherapy, and explores potential mechanisms of cancer cells to induce export of these proteins. Novel drugs that could potentially counteract nuclear export of specific proteins are also discussed.
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PMID:CRM1-mediated nuclear export of proteins and drug resistance in cancer. 1899 27

Mammary cancer is among the most frequently observed canine tumors in unspayed female dogs resulting in death due to metastatic disease. These tumors are excellent models of human breast cancer but until recently there was only anecdotal evidence regarding underlying genetic defects. We recently reported expression defects in the cyclin-dependent kinase p21/Cip1 and p53 among three independent canine mammary tumor (CMT) cell lines derived from spontaneous canine mammary cancers. We investigated further defects in the same three cell lines focusing on additional tumor suppressor gene defects in cyclin-dependent kinase inhibitors. p27/KIP1 appeared normally expressed and did not appear to encode inactivating mutations. In contrast, expression of p16/INK4A was defective/absent in two cell lines and normal/slightly induced in the third cell line. To determine if defects were causative in maintaining the transformed phenotype, a p16/INK4A transgene was permanently transfected followed by selection and single cell cloning. CMT/p16 clones were characterized for transgene expression, p16 protein content and phenotype including proliferation rate, cell cycle phase distribution, contact inhibition, substrate dependent cell growth and cell morphology. All cell lines appeared unique yet clear indications of phenotype rescue due to p16/INK4A transgene complementation were observed suggesting that defects in p16 expression were present in all three. In some cases cellular senescence also appeared to be induced. These data provide evidence supporting p16/INK4A mutations as causative defects promoting transformation in canine mammary cancer and further characterizes tumor suppressor gene defects with functional consequences in these cells supporting their application as spontaneous animal models of human disease.
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PMID:Phenotype-rescue of cyclin-dependent kinase inhibitor p16/INK4A defects in a spontaneous canine cell model of breast cancer. 1913 Apr 92

Flavokawain A is the predominant chalcone from kava extract. We have assessed the mechanisms of flavokawain A's action on cell cycle regulation. In a p53 wild-type, low-grade, and papillary bladder cancer cell line (RT4), flavokawain A increased p21/WAF1 and p27/KIP1, which resulted in a decrease in cyclin-dependent kinase-2 (CDK2) kinase activity and subsequent G(1) arrest. The increase of p21/WAF1 protein corresponded to an increased mRNA level, whereas p27/KIP1 accumulation was associated with the down-regulation of SKP2, which then increased the stability of the p27/KIP1 protein. The accumulation of p21/WAF1 and p27/KIP1 was independent of cell cycle position and thus not a result of the cell cycle arrest. In contrast, flavokawain A induced a G(2)-M arrest in six p53 mutant-type, high-grade bladder cancer cell lines (T24, UMUC3, TCCSUP, 5637, HT1376, and HT1197). Flavokawain A significantly reduced the expression of CDK1-inhibitory kinases, Myt1 and Wee1, and caused cyclin B1 protein accumulation leading to CDK1 activation in T24 cells. Suppression of p53 expression by small interfering RNA in RT4 cells restored Cdc25C expression and down-regulated p21/WAF1 expression, which allowed Cdc25C and CDK1 activation, which then led to a G(2)-M arrest and an enhanced growth-inhibitory effect by flavokawain A. Consistently, flavokawain A also caused a pronounced CDK1 activation and G(2)-M arrest in p53 knockout but not in p53 wild-type HCT116 cells. This selectivity of flavokawain A for inducing a G(2)-M arrest in p53-defective cells deserves further investigation as a new mechanism for the prevention and treatment of bladder cancer.
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PMID:Effects of the kava chalcone flavokawain A differ in bladder cancer cells with wild-type versus mutant p53. 1913 91

Energy balance and the AKT pathway are important in colorectal cancer development and regulate p27 (cyclin-dependent kinase inhibitor-1B/CDKN1B/KIP1), which plays a role in preventing cell cycle progression. However, little is known on the clinical outcome or prognostic significance of p27 alterations in relation to patient body mass index (BMI). Among 630 colon cancers (stage I-IV) in two prospective cohort studies, we detected p27 alterations (cytoplasmic p27 localization or p27 loss) in 500 tumors (79%) by immunohistochemistry. The remaining 130 (21%) tumors were "p27-nuclear+." Cox proportional hazard models computed hazard ratios (HR) of deaths, adjusted for patient and tumoral characteristics, including p53, p21, cyclin D1, KRAS, BRAF, PIK3CA, cyclooxygenase-2, fatty acid synthase (FASN), beta-catenin, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and long interspersed nucleotide element-1 (LINE-1) hypomethylation. Compared with p27-nuclear+ patients, p27-altered patients experienced low colon cancer-specific [adjusted HR, 0.63; 95% confidence interval (95% CI), 0.42-0.94] and overall mortality (adjusted HR, 0.70; 95% CI, 0.51-0.95), independent of FASN, MSI, CIMP, LINE-1 methylation, and other potential confounders. The effect of p27 alteration on overall mortality significantly differed by BMI (P(interaction) = 0.013); adjusted HR (p27-altered versus p27-nuclear+ tumors) was 0.28 (95% CI, 0.13-0.59) for BMI >or=30 kg/m(2), 0.67 (95% CI, 0.40-1.14) for BMI 25 to 29 kg/m(2), and 0.91 (95% CI, 0.57-1.46) for BMI <25 kg/m(2). Obesity was associated with inferior overall survival among p27-nuclear+ cases (adjusted HR, 3.07; 95% CI, 1.49-6.32; versus nonobese cases), but not among p27-altered cases (adjusted HR, 1.08). In conclusion, p27 alterations in colon cancer are associated with superior prognosis. Adverse prognostic effect of obesity seems limited to patients with nuclear p27 expression, suggesting a host-tumor interaction.
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PMID:A cohort study of p27 localization in colon cancer, body mass index, and patient survival. 1950 18

Helenalin is a naturally occuring sesquiterpene lactone extracted from Arnica montana and Arnica chamissonis ssp. foliosa. Helenalin and its derivatives are known for anti-cancer and anti-inflammatory effects via inhibiting NF-kappaB and telomerase activity and impairing protein and DNA synthesis, suggesting that helenalin is a potential candidate for the treatment of deregulated and unwanted T cell-mediated immune responses. Here we show that helenalin induces apoptosis in activated CD4+ T cells by triggering the mitochondrial pathway of apoptosis. Induction of apoptosis is accompanied by rapid stabilization of p53, nuclear localization of p53 and AIF, and an increase in ROS production that results in loss of mitochondrial membrane potential (DeltaPsim). Activated CD4+ T cells which survive exposure to helenalin undergo inhibition of proliferation by induction of G2/M cell cycle arrest. Cell cycle arrest is accompanied by the accumulation of cell cycle regulator proteins p21(WAF/CIP1), p2(KIP1) and cyclin D2, whereas abundance of cyclin A and B(1) is decreased. Cell surface expression of the activation-associated receptors CD25, CD27, CD28, CD120b as well as production of IL-2 are impaired. Transcriptional activation of genes encoding for CD25, IL-2 and IFN-gamma is mediated by transcription factors of the NFAT family, and we demonstrate that helenalin suppresses nuclear translocation of NFATc2 in activated CD4+ T cells. Thus, helenalin can be defined as a new immunosuppressive compound suited for the treatment of deregulated and unwanted T cell-mediated immune responses.
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PMID:Helenalin suppresses essential immune functions of activated CD4+ T cells by multiple mechanisms. 1965 71

In urodele amphibians, a critical step in limb regeneration is the cellularization and dedifferentiation of skeletal muscle. In contrast, mammalian skeletal muscle does not undergo this response to injury. We have developed a novel simple, stepwise chemical method to induce dedifferentiation and multipotency in mammalian skeletal muscle. Optimal muscle fiber cellularization was induced by the trisubstituted purine small molecule, myoseverin, compared to colchicine, nocodazole, or myoseverin B. The induction of a proliferative response in the cellulate was found to be a crucial step in the dedifferentiation process. This was achieved by down-regulation of the cyclin-dependent kinase inhibitor, p21 (CDKN 1A, CIP1). p21 was found to be a key regulator of this process, because down-regulation of the cyclin-dependent kinase inhibitors p27 (CDKN1B/KIP1) or p57 (CDKN1C/KIP2) or the tumor suppressor p53 (TP53/LFS1) failed to induce proliferation and subsequent dedifferentiation. Treatment with the small molecule reversine (2-(4-morpholinoanilino)-6-cyclohexylaminopurine) during this proliferative "window" induced the muscle cellulate to differentiate into non-muscle cell types. This lineage switching was assessed using a relatively stringent approach, based on comparative functional and phenotypic assays of cell-type specific properties. This showed that our chemical method allowed the derivation of adipogenic and osteogenic cells that possessed a degree of functionality. This is the first demonstration that mammalian muscle culture can be induced to undergo cellularization, proliferation, and dedifferentiation, which is grossly similar to the key early steps in urodele limb regeneration. These results, based solely on the use of simple chemical approaches, have implications for both regenerative medicine and stem cell biology.
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PMID:Novel chemically defined approach to produce multipotent cells from terminally differentiated tissue syncytia. 2132 36

Experimental studies have shown that estrogen- or progesterone-activated signaling leads to growth inhibition effects on colon cancer cells through the upregulation of several cell-cycle regulators. However, epidemiologic studies evaluating hormone therapy use and colorectal cancer risk by the status of cell-cycle regulators are lacking. In this study, we used data from the prospective Nurses' Health Study to evaluate whether the association between hormone therapy use and colorectal cancer risk differs by the molecular pathologic status of microsatellite instability (MSI) and expression of cell-cycle-related tumor biomarkers, including CDKN1A (p21, CIP1), CDKN1B (p27, KIP1), and TP53 (p53) by immunohistochemistry. Duplication Cox regression analysis was used to determine an association between hormone therapy use, cancer risk, and specific tumor biomarkers in 581 incident colon and rectal cancer cases that occurred during 26 years of follow-up among 105,520 postmenopausal women. We found a difference between hormone therapy use and colorectal cancer risk according to CDKN1A expression (P(heterogeneity) = 0.01). Current hormone therapy use was associated with a reduced risk for CDKN1A-nonexpressed [multivariate relative risk (RR), 0.61; 95% confidence interval (CI), 0.46-0.82] but not for CDKN1A-expressed (RR, 1.32; 95% CI, 0.76-2.31) tumors. The lower risk for CDKN1A-nonexpressed but not for CDKN1A-expressed cancers was also present among current users of estrogen-alone therapy. We found no significant difference in the relations between hormone therapy use and cancer risk according to MSI, CDKN1B, or TP53 status. Together, our molecular pathological epidemiology findings suggest a preventive effect of hormone therapy against colorectal carcinogenesis that depends, in part, on loss of cyclin-dependent kinase inhibitor CDKN1A.
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PMID:Postmenopausal hormone therapy is associated with a reduced risk of colorectal cancer lacking CDKN1A expression. 2251 78

Hypermethylation of CpG islands leads to transcriptional silencing and it is the predominant mechanism of tumor suppressor gene inactivation in many tumors. Methylation-specific polymerase chain reaction was performed to analyse the methylation status of the promoter region of the tumor suppressor genes. Hypermethylation of the 5' CpG island of the p21 ( CIP1 ), p27 ( KIP1 ), p57 ( KIP2 ), p53, p73 and RB 1 gene promoter were found in 8.8, 8.8, 11.2, 12, 25.6 and 4.8 % of 125 cervical cancer samples from north Indian population, respectively. Methylation of p73 was significantly (P < 0.001) associated with the cervical cancer cases in comparison to controls. Significant correlation was also observed between the methylation of p73 gene and increase in the risk of cervical cancer among passive smokers. Promoter hypermethylation of p53 gene was also observed to be significant among oral contraceptive users and cervical cancer patients having age at first sexual intercourse <20 years whereas hypermethylation of other genes was not found to be significant in the present study. This is the first report showing significant hypermethylation of p73 and p53 genes among cervical cancer patients in north Indian population. This is also the first report on significant p53 hypermethylation in cervical cancer in any population. Our findings did not show any correlation between promoter methylation of p73 and the other genes under study with clinicopathological parameters, including human papillomavirus infection and stage of the disease. The frequency of aberrant methylation of p73 and p53 gene promoter was unchanged according to the age of patients.
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PMID:Promoter hypermethylation of p73 and p53 genes in cervical cancer patients among north Indian population. 2272 11


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