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)

Future progress in mechanism-based cancer prevention research may be facilitated by animal models displaying specific genetic susceptibilities for cancer, such as mice deficient in 1 (+/-) or both (-/-) alleles of the p53 tumor suppressor gene. We observed in p53-/- mice that calorie restriction (CR) increased the latency of spontaneous tumor development (mostly lymphomas) by approximately 75%, decreased serum insulin-like growth factor-1 (IGF-1) and leptin levels, slowed thymocyte cell cycle traverse, and induced apoptosis in immature thymocytes. In p53+/- mice, CR and a 1 d/wk fast each delayed spontaneous tumor development (a mix of lymphomas, sarcomas, and epithelial tumors) and decreased serum IGF-1 and leptin levels, even when begun late in life. In p53+/-Wnt-1 transgenic mice, a mammary tumor model, the same interventions increased mammary tumor latency and reduced mean serum IGF-1 and leptin levels to <50% of those of control mice. We capitalized on the susceptibility of p53+/- mice to chronic, low-dose aromatic amine-induced bladder carcinogenesis to develop a useful model for evaluating bladder cancer prevention approaches. These examples clearly indicate that mice with specific (and humanlike) genetic susceptibilities for cancer are powerful models for testing interventions that may inhibit carcinogenesis in humans.
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PMID:Cancer prevention studies in p53-deficient mice. 1121 77

Progress in mechanism-based cancer prevention research may be facilitated by the use of animal models displaying specific genetic susceptibilities for cancer such as mice deficient in the p53 tumor suppressor gene, the most frequently altered gene in human cancer. We observed in p53-knockout (p53-/-) mice that calorie restriction (CR; 60% of the control group's intake of carbohydrate energy) increased the latency of spontaneous tumor development (mostly lymphomas) approximately 75%, decreased serum insulin-like growth factor (IGF)-1 and leptin levels, significantly slowed thymocyte cell cycle traverse and induced apoptosis in immature thymocytes. In heterozygous p53-deficient (p53+/-) mice, CR and 1 d/wk of food deprivation each significantly delayed spontaneous tumor development (a mix of lymphomas, sarcomas and epithelial tumors) and decreased serum IGF-1 and leptin levels even when begun late in life. We have also developed a rapid and relevant p53+/- mouse mammary tumor model by crossing p53-deficient mice with MMTV-Wnt-1 transgenic mice, and found that CR and 1 d/wk food deprivation significantly increased mammary tumor latency (greater than twofold) and reduced the mean serum IGF-1 and leptin levels to <50% of that of control mice (P < 0.0001). In addition, fluasterone, fenretinide and soy each delayed tumor development but had little effect on IGF-1 or leptin levels. We have capitalized on the susceptibility of p53+/- mice to chronic, low dose, aromatic amine-induced bladder carcinogenesis to develop a useful model for evaluating bladder cancer prevention approaches such as cyclooxygenase-2 inhibition. As demonstrated by these examples, mice with specific (and human-like) genetic susceptibilities for cancer provide powerful new tools for testing and characterizing interventions that may inhibit the process of carcinogenesis in humans.
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PMID:Diet and cancer prevention studies in p53-deficient mice. 1169 54

Heterozygous p53-deficient (p53(+/-)) mice, a potential model for human Li-Fraumeni Syndrome, have one functional allele of the p53 tumor suppressor gene. These mice are prone to spontaneous neoplasms, most commonly sarcoma and lymphoma; the median time to death of p53+/- mice is 18 months. We have shown previously that juvenile-onset calorie restriction (CR) to 60% of ad libitum (AL) intake delays tumor development in young p53-null (-/-) mice by a p53-independent and insulin-like growth factor 1 (IGF-1)-related mechanism. To determine whether CR is effective when started in adult p53-deficient mice, and to compare chronic CR with an intermittent fasting regimen, male p53+/- mice (7-10 months old, 31-32 mice/group) were randomly assigned to the following regimens: (i) AL (AIN-76A diet), (ii) CR to 60% of AL intake or (iii) 1 day/week fast. Food availability on non-fasting days was controlled to prevent compensatory over feeding. Relative to the AL group, CR significantly delayed (P = 0.001) the onset of tumors in adult mice, whereas the 1 day/week fast caused a moderate delay (P = 0.039). Substantial variation in longevity and maximum body weight within treatments was not correlated with variation in growth characteristics of individual mice. In a separate group of p53+/- mice treated for 4 weeks (n = five mice per treatment), plasma IGF-1 levels in CR versus AL mice were reduced by 20% (P < 0.01) and leptin levels were reduced by 71% (P < 0.01); fasted mice had intermediate levels of leptin and IGF-1. Our findings that CR or a 1 day/week fast suppressed carcinogenesis-even when started late in life in mice predestined to develop tumors due to decreased p53 gene dosage-support efforts to identify suitable interventions influencing energy balance in humans as a tool for cancer prevention.
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PMID:Adult-onset calorie restriction and fasting delay spontaneous tumorigenesis in p53-deficient mice. 1201 55

Pivotal genetic information has been derived for a host of rare genetic disorders, but progress has been much slower in relation to the common causes of female infertility. In this chapter, we shall illustrate the approaches being applied in elucidating conditions causing infertility that are inherited in a polygenic/multifactorial fashion. The task is to determine the number of genes responsible and their chromosomal location(s). The first approach is to use genome-wide quantitative linkage analysis, searching throughout the genome with no prior expectation that a given gene or chromosomal region is casually involved. A second approach is to search across the genome for altered gene expression, for example comparing endometriosis and normal (non-endometriosis)cells. The third approach is less indiscriminate and more focused, depending upon identifying specific candidate genes. Aromatase, calhedrin, oestrogen receptor, galactose-1-phosphate uridyl transferase (GALT) and tumour suppressor genes such as p53 are attractive candidate genes for endometriosis. Endometriosis, which has long been suspected to possess a familial tendency, has been subjected to genome-wide linkage analysis in Oxford, UK, where sib-pair analysis uses polymorphic DNA markers and fluorescence-based automated analysis. Several regions of exclusion have been found, but no linkages have so far been reported. A candidate gene approach focuses on the presence of chromosomal aberrations, the assumption being that endometriosis parallels neoplasia. At Baylor College of Medicine, we thus began by showing chromosome alterations involving trisomy 11, monosomy 16 and monosomy 17 in late-stage endometriosis. A loss of only the p53 tumour suppressor gene, rather than a loss (monosomy) of chromosome 17 per se, however, seems to be the pivotal event. A second representative polygenic/multifactorial disorder causing female infertility is polycystic ovarian syndrome. Both quantitative linkage analysis and candidate gene approaches are being pursued. In the far more commonly observed 'idiopathic' variety (non-adrenal polycystic ovarian syndrome and hirsutism), consensus has long existed that one or more dominant genes causes the condition. Although the mode of inheritance in 'essential' polycystic ovarian syndrome remains uncertain, dominant tendencies are clearly more pertinent than recessive ones. Genes for adrenal biosynthetic enzymes, insulin receptors, leptin and leptin receptors, follistatin, activin and inhibins are attractive candidates for polycystic ovarian disease. A linkage to 37 candidate genes was sought using affected sib-pair analysis and transmission/disequilibrium methods.
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PMID:Molecular approach to common causes of female infertility. 1247 48

Progress in cancer prevention research is being facilitated by the use of animal models displaying specific genetic susceptibilities for cancer, such as mice deficient in one (+/-) or both (-/-) alleles of the p53 tumor suppressor gene. Our lab, which focuses on nutrition (particularly energy balance/obesity) and molecular carcinogenesis, has shown in p53-/- mice that calorie restriction (CR) increases the latency of spontaneous tumor development (mostly lymphomas) approximately 75%, decreases serum insulin-like growth factor (IGF)-1 and leptin levels, and induces apoptosis in immature (lymphoma-susceptible) thymocytes. In heterozygous p53-deficient (p53+/-) mice, CR and a one day/wk fast each significantly delay spontaneous tumor development (a mix of lymphomas, sarcomas, and epithelial tumors) and decreases serum IGF-1 and leptin levels, even when begun late in life. We are presently comparing and combining CR and exercise (treadmill and running wheel) to further elucidate the relationships between energy balance, p53, and tumorigenesis in these models. Furthermore, we have capitalized on the susceptibility of p53+/- mice to chronic, low-dose aromatic amine-induced bladder carcinogenesis to develop a model for evaluating bladder cancer prevention approaches. Using this model, we have established that IGF-1 mediates many of the anti-cancer effects of CR. We are currently conducting oligonucleotide microarray studies to further characterize diet-gene interactions underlying the anti-cancer effects of CR and to determine which of the CR-responsive genes are IGF-1 dependent.
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PMID:Diet-gene interactions in p53-deficient mice: insulin-like growth factor-1 as a mechanistic target. 1533 46

Evidence has accumulated from laboratory-based animal experiments and population-based human epidemiological studies that lifestyle factors that affect energy balance, such as caloric intake, nutritional status, and exercise, act in concert with genetic susceptibility to influence cancer development and progression. The use of animal models with specific genetic alterations, in combination with lifestyle modifications that alter overall energy balance, has contributed to a greater understanding of the mechanistic changes occurring during carcinogenesis and to the identification of points of intervention. Studies in our laboratory focusing on the role of energy balance and genetic susceptibility in mice deficient in one (+/-) or both (-/-) alleles of the p53 tumor suppressor gene and mice with a mutant APC allele (APC(Min)) showed that calorie restriction decreases tumor burden, increases tumor latency, and decreases serum insulin-like growth factor (IGF)-1 and leptin levels. Data from our studies, combined with results from other animal and human studies, have established a role for IGF-1 in carcinogenesis. Studies using genetic models of cancer that have been interbred with mice with abnormal levels of IGF-1 will enable the examination of combined effects of energy balance and genetic alterations on the cancer process. Models that integrate lifestyle and genetic effects in a single system provide a physiologically intact system in which combination interventions and therapies for cancer prevention can be tested and validated, thus building a strong preclinical foundation that will inform the development of clinical trials and add perspective to epidemiological studies.
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PMID:Effects of energy balance on cancer in genetically altered mice. 1557 44

We describe the immunohistochemical profile of rare primary squamous carcinoma of the clitoris metastasizing to the bilateral inguinal lymph nodes. Several antigens were assessed immunohistochemically (pRb1, p16INK4A, cyclin D1, cdk4, estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), p53, Ki-67, p27KIP1, PTEN, hMLh1, phospho-AKT, collagen IV, leptin and CD90) in both tumors. All the antibodies applied revealed a staining pattern that is typical of primary and metastatic carcinomas. Cyclin D1-cdk4 complex was overexpressed, whereas there was no p16INK4A immunostaining. Moreover, both tumors expressed positivity for p53 protein, but were negative for estrogen and progesterone receptors. The proliferative activity of cancer, assessed by MIB-1 Proliferative Index, amounted to 25% either for primary or for metastatic tumors. As a conclusion, immunohistochemical assessment of various cell-cycle-associated molecules yield clues as to their possible function during the process of spread of rare neoplasm originating from the clitoris.
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PMID:The immunohistochemical profile of the primary and metastatic carcinoma of the clitoris: a case report. 1616 59

Obesity has been recognized as a risk factor for breast cancer. Adipocyte-derived leptin may play as a paracrine regulator on the growth of breast cancer cells. Expression of both leptin and its OB-Rb receptor was detected in human breast cancer ZR-75-1 cells and further induced by leptin, suggesting that both expression and message mediation of leptin were autoregulated by itself. With cell counting and MTT assay, we had observed leptin stimulated ZR-75-1 growth in dose- and time-dependent manners. To study what steps of cell cycle progression leptin may involve in, we analyzed cell-cycle profile with flow cytometric analysis, mRNA and protein expressions of four cell-cycle regulators with RT-PCR and Western blotting analysis. Under the treatment of leptin, the G1 arrest of cells was reduced accompanied with up-regulation of G1 phase-specific cyclin D1 and proto-oncogene c-Myc, but down-regulation of cyclin-dependent kinase inhibitor p21(WAF1/CIP1) and tumor suppressor p53. Furthermore, JAK2 inhibitor AG490, PI3K/Akt inhibitor Wortmannin, and MEK/ERK1/2 inhibitor PD98059 were efficiently prevented leptin-promoted cell growth. Effect of cooperation between leptin and estrogen on ZR-75-1 growth had been observed. Collectively, the results showed that the proliferative effect of leptin on ZR-75-1 was associated with the up-regulation of cyclin D1 and c-Myc and down-regulation of tumor suppressor p53 and p21(WAF1/CIP1) plausibly through a hypothesized JAK2-PI3K/Akt-MEK/ERK pathway. The leptin- and OB-Rb-expressing capability of ZR-75-1 created a possible autocrine control of leptin, in which signal could be effectively amplified by itself, on cell growth.
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PMID:Leptin-induced growth of human ZR-75-1 breast cancer cells is associated with up-regulation of cyclin D1 and c-Myc and down-regulation of tumor suppressor p53 and p21WAF1/CIP1. 1675 79

Obesity is typically associated with increased tumor susceptibility, whereas caloric restriction, a regimen resulting in leanness, inhibits carcinogenesis. The link between adiposity and malignancies suggests that adipose tissue may influence carcinogenesis. An adipose tissue hormone, leptin, could be procarcinogenic because it stimulates proliferation in various tissues and tumor cell lines. Leptin may contribute to the correlation between adiposity and malignancies as its levels are usually increased in obese subjects and reduced by caloric restriction. We hypothesized that leptin deficiency, despite obesity, would inhibit carcinogenesis in leptin-null ob/ob mice and tested this hypothesis in two models: (a) two-stage skin carcinogenesis initiated by 7,12-dimethylbenz(a)anthracene and promoted by phorbol 12-myristate 13-acetate (PMA) and (b) p53 deficiency. Contrary to a typical association between obesity and enhanced carcinogenesis, obese ob/ob mice developed induced skin papillomas and spontaneous p53-deficient malignancies, mostly lymphomas, similarly to their lean littermates. Surprisingly, lipodystrophic (ZIP) mice that had very little both adipose tissue and leptin were highly susceptible to carcinogenesis. Hyperphagia, hyperinsulinemia, and hyperglycemia are unlikely to have contributed significantly to the enhancement of carcinogenesis in ZIP mice because similarly hyperphagic, hyperinsulinemic, and hyperglycemic ob/ob mice had normal susceptibility to carcinogenesis. Our data suggest that, in contrast to a well-known correlation between obesity and cancer, the direct effect of adipose tissue may rather be protective.
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PMID:Susceptibility to induced and spontaneous carcinogenesis is increased in fatless A-ZIP/F-1 but not in obese ob/ob mice. 1695 Dec 7

The aim of our in-vitro experiments was to examine, whether leptin can directly control functions of avian ovarian cells and to outline potential intracellular mediators of its effects. Granulosa cells or fragments of ovarian follicular wall were cultured with leptin (0, 1, 10 or 100 ng/mL medium). The expression of peptides involved in apoptosis (TdT, bax, its binding protein, bcl-2, ASK-1 and p53), cell cycle-related peptides (PCNA and cyclin B1), release of hormones (progesterone, testosterone, estradiol, arginine-vasotocin), as well as the expression of protein kinases (PKA, MAPK/ERK1,2 and CDK/p34) in the ovarian cells were examined by using immunocytochemistry, TUNEL, SDS-PAGE-Western immunoblotting, EIA and RIA. It was found that leptin inhibited expression of all markers of cytoplasmic apoptosis (bax, ASK-1 and p53), stimulated expression of anti-apoptotic peptide bcl-2, but did not affect nuclear DNA fragmentation (TdT). Furthermore, leptin inhibited expression of PCNA (marker of S-phase of mitosis), but not of cyclin B1 (marker of G phase of cell cycle). Moreover, it promoted release of progesterone and estradiol, suppressed release of testosterone, but did not affect arginine-vasotocin. Finally, leptin inhibited expression of MAPK/ERK1,2 and CDK/p34 and stimulated expression of PKA. The present observations demonstrate that leptin can directly control basic chicken ovarian functions - inhibit cytoplasmic apoptosis and proliferation (S-phase, but not G-phases of mitosis), regulate secretory activity (release of steroids, but not nonapeptide hormone) and expression of MAPK, PKA and CDC2, which might be potential intracellular mediators of leptin action.
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PMID:Leptin directly controls proliferation, apoptosis and secretory activity of cultured chicken ovarian cells. 1760 68


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