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)

In order to confirm the role of 14-3-3 sigma (sigma) as a tumor suppressor in breast carcinogenesis, we have studied the expression of 14-3-3sigma immunohistochemically in usual ductal hyperplasia (UDH), ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) breast lesions. Immunostaining for estrogen receptor alpha (ERalpha), p53 and estrogen-responsive RING finger protein (Efp) was also carried out. Immunohistochemically, expression of 14-3-3sigma was seen in 92% UDH lesions and gradually decreased from 65% in DCIS to 23% in IDC. The expression of ERalpha decreased gradually from UDH to DCIS to IDC, while p53 showed an inverse staining pattern to that of ERalpha. The expression of Efp showed no significant difference among the three breast lesions. Hence, the present immunohistochemical study confirmed 14-3-3sigma as a tumor suppressor in breast carcinogenesis. A similar immunohistochemical analysis was then carried out on columnar cell hyperplasia with atypia (CCHA), in which the expression pattern of tumor suppressor 14-3-3sigma, ERalpha and p53 suggested that it might be possible that CCHA is a precancerous lesion.
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PMID:Immunohistochemical analysis of 14-3-3 sigma and related proteins in hyperplastic and neoplastic breast lesions, with particular reference to early carcinogenesis. 1526 Aug 50

14-3-3 sigma:, a target gene of the p53 tumour suppressor protein, has been shown to regulate the cell cycle at the G2/M checkpoint. Recent studies have demonstrated that 14-3-3 sigma is downregulated by hypermethylation of the CpG island in several types of cancer. In this study, we investigated the expression and methylation status of 14-3-3 sigma in human salivary gland adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC). Immunohistochemical analysis revealed that the positive expression rate of 14-3-3 sigma in ACC (one out of 14) was markedly lower than that in MEC (ten out of 10). Since most of the ACCs carried the wild-type p53 protein, downregulation of 14-3-3 sigma in ACC may not be due to the dysfunction of p53 pathway. Microdissection-methylation-specific PCR revealed that frequent hypermethylation of the 14-3-3 sigma gene was observed in ACC when compared to that in MEC. In cultured-ACC cells, we confirmed the downregulation of 14-3-3 sigma via hemimethylation of the gene by sequencing analysis after sodium bisulphite treatment. Furthermore, re-expression of 14-3-3 sigma in the ACC cells was induced by the treatment with DNA demethylating agent, 5-aza-2'-deoxycytidine. Irradiation apparently induced the enhanced expression of 14-3-3 sigma and G2/M arrest in normal salivary gland cells; however, in the ACC cells, neither induction of 14-3-3 sigma nor G2/M arrest was induced by irradiation. These results suggest that downregulation of 14-3-3 sigma might play critical roles in the neoplastic development and radiosensitivity of ACC.
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PMID:Frequent downregulation of 14-3-3 sigma protein and hypermethylation of 14-3-3 sigma gene in salivary gland adenoid cystic carcinoma. 1529 43

p53 family members with a transactivation (TA) domain induce cell cycle arrest and promote apoptosis. However, DeltaNp63 isotypes lacking the TA-domain promote cell proliferation and tumorigenesis in vitro and in vgammavo. Although p53, TAp63 or TAp73 are stabilized upon DNA damage, we found that the genotoxic stress agents induced a dramatic decrease and phosphorylation of DeltaNp63alpha in squamous cell carcinoma cells. Further work revealed that RACK1 physically associated with the p63alpha C-terminal domain through its WD40 domain. However, stratifin binds with phosphorylated DeltaNp63alpha in response to cisplatin. Upon DNA damage induced by cisplatin, stratifin mediated a nuclear export of DeltaNp63alpha into cytoplasm and then RACK1 targeted latter into a proteasome degradation pathway possibly serving as an E3 ubiquitin ligase. Moreover, siRNA knockdown of both stratifin and RACK1 inhibited a nuclear export and protein degradation of DeltaNp63alpha, respectively. Our data suggest that modification and down regulation of DeltaNp63alpha is one of the major determinants of the cellular response to DNA damage in human head and neck cancers.
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PMID:RACK1 and stratifin target DeltaNp63alpha for a proteasome degradation in head and neck squamous cell carcinoma cells upon DNA damage. 1546 55

14-3-3 sigma (sigma) has been a major G2/M checkpoint control gene and has demonstrated that its inactivation in various cancers occurs mostly by epigenetic hypermethylation, not by genetic change. In order to confirm 14-3-3sigma protein expression together with p16 and p53 in cervical cancers, immunohistochemistry was performed using various histological subtypes of cervical cancers and dysplasia. Strong and diffuse immunoreactivity for 14-3-3sigma was uniformly observed in all the cervical dysplasia (17/17) and squamous cell carcinomas (29/29) including human papillomavirus (HPV)-negative cases. Even in adenosquamous carcinomas and adenocarcinomas of the cervix, immunohistochemical expression of 14-3-3sigma was shown with relatively high frequency (13/15, 87% and 22/27, 81%). In the in situ hybridization study, mRNA of 14-3-3sigma was expressed in six of eight immunohistochemical-negative cases. Therefore, the undetectable expression of 14-3-3sigma protein in cervical cancers might, at least in part, be due to a proteolysis not epigenetic hypermethylation. It is of interest that cancers without 14-3-3sigma expression were predominantly those lacking HPV DNA, and that there were no cases with concomitant inactivation of 14-3-3sigma and p16 in the present study. These observations are consistent with the hypothesis that inactivation of either 14-3-3sigma or p16 has an effect equivalent to the expression of E6 and E7 oncoproteins of HPV.
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PMID:Immunohistochemical expression of 14-3-3 sigma protein in various histological subtypes of uterine cervical cancers. 1548 63

14-3-3 Sigma is a checkpoint control gene that promotes G2 arrest following DNA damage. The inactivation of the 14-3-3 sigma gene, primarily by methylation-mediated silencing, has been reported in various human cancers. The loss of 14-3-3 sigma expression may contribute to malignant transformation by impairing the G2/M cell cycle checkpoint function, allowing an accumulation of genetic defects. In this report, we measured 14-3-3 sigma expression in 34 gastric and 35 colorectal cancers by using semi-quantitative reverse transcription-polymerase chain reaction and Western blot analysis. We also analyzed the association between 14-3-3 sigma expression and clinicopathological parameters including p53 status. Semi-quantitative reverse transcription-polymerase chain reaction and Western blot analysis showed that 14-3-3 sigma was significantly overexpressed in gastric and colorectal cancer tissues compared with normal ones (P<0.01). The immunoreactive 14-3-3 sigma protein was mainly detected in cytoplasm of cancer cells. Sigma overexpression tended to be associated with lymph node metastasis (P=0.08) in colorectal cancer. There was significant correlation between 14-3-3 sigma protein expression and the Ki-67 labeling index in gastric cancer (P=0.001). No significant association was observed between 14-3-3 sigma expression and p53 status. These results suggest that overexpressed 14-3-3 sigma in cancer cells might be induced by the p53 independent pathway, and that increased 14-3-3 sigma expression could contribute to cancer cell proliferation and the development and/or progression of human gastrointestinal cancers.
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PMID:The clinical implication of 14-3-3 sigma expression in primary gastrointestinal malignancy. 1554 95

To comprehensively identify proteins interacting with 14-3-3 sigma in vivo, tandem affinity purification and the multidimensional protein identification technology were combined to characterize 117 proteins associated with 14-3-3 sigma in human cells. The majority of identified proteins contained one or several phosphorylatable 14-3-3-binding sites indicating a potential direct interaction with 14-3-3 sigma. 25 proteins were not previously assigned to any function and were named SIP2-26 (for 14-3-3 sigma-interacting protein). Among the 92 interactors with known function were a number of proteins previously implicated in oncogenic signaling (APC, A-RAF, B-RAF, and c-RAF) and cell cycle regulation (AJUBA, c-TAK, PTOV-1, and WEE1). The largest functional classes comprised proteins involved in the regulation of cytoskeletal dynamics, polarity, adhesion, mitogenic signaling, and motility. Accordingly ectopic 14-3-3 sigma expression prevented cellular migration in a wounding assay and enhanced mitogen-activated protein kinase signaling. The functional diversity of the identified proteins indicates that induction of 14-3-3 sigma could allow p53 to affect numerous processes in addition to the previously characterized inhibitory effect on G2/M progression. The data suggest that the cancer-specific loss of 14-3-3 sigma expression by epigenetic silencing or p53 mutations contributes to cancer formation by multiple routes.
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PMID:Targeted proteomic analysis of 14-3-3 sigma, a p53 effector commonly silenced in cancer. 1577 65

CKBM is a natural product that exhibits a novel anti-tumor activity through the induction of cell cycle arrest and apoptosis. We have investigated its effects on cell cycle regulation using a gastric cancer cell line, AGS. The effects of CKBM on cell proliferation, cell cycle regulation and apoptosis were analyzed using BrdU (5-bromo-2'-deoxyuridine) cell proliferation assay and flow cytometric analysis, respectively. Specific cellular protein expressions were measured using Western blot analysis. Flow cytometric analysis indicated that CKBM induced G2/M cell cycle arrest and apoptosis, whereas differential protein expressions of p21, p53 and 14-3-3sigma (stratifin) using Western blot analysis were enhanced. The differential expressions of p21, p53 and 14-3-3sigma in AGS cancer cells after CKBM treatment may play critical roles in the G2/M cell cycle arrest that blocks cell proliferation and induces apoptosis.
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PMID:Cell Cycle Arrest by a Natural Product via G2/M Checkpoint. 1596 42

We cloned rat 14-3-3 sigma, a mediator of p53 tumor suppressor, as a target of K-selection. 14-3-3 sigma expression is suppressed with DNA methylation in breast cancers while its overexpression with hypomethylation is frequent in pancreatic cancers. These opposite findings were recapitulated through r- and K-selection of transformed rat embryo fibroblasts. 14-3-3 sigma expression was suppressed with DNA methylation after r-selection and the gene was overexpressed and demethylated in K-selected cells. 5-aza-2'-deoxycytidine recovered 14-3-3 sigma expression in r-selected cells. The presence of heterogeneous methylation patterns and expression levels before selection suggests that different 14-3-3 sigma expression levels play a role as a prerequisite for selection and clonal evolution.
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PMID:Differential 14-3-3 sigma DNA methylation and expression in c-myc- and activated H-ras-transformed cells under r- and K-selection. 1597 84

Mutations in the tumor suppressor gene p53 were found in more than 90% of all human squamous cell carcinomas (SCC). To study the function of p53 in a keratinocyte background, a tetracycline-controlled p53 transgene was introduced into a human SCC cell line (SCC15), lacking endogenous p53. Conditional expression of wild-type p53 protein upon withdrawal of tetracycline was accompanied with increased expression of p21(WAF1/Cip1) resulting in reduced cell proliferation. Flow-cytometric analysis revealed that these cells were transiently arrested in the G1/S phase of the cell cycle. However, when SCC15 cells expressing p53 were exposed to ionizing radiation (IR), a clear shift from a G1/S to a G2/M cell cycle arrest was observed. This effect was greatly depending on the presence of wild-type p53, as it was not observed to the same extent in SCC15 cells lacking p53. Unexpectedly, the p53- and IR-dependent G2/M cell cycle arrest in the keratinocyte background was not depending on increased expression or stabilization of 14-3-3sigma, a p53-regulated effector of G2/M progression in colorectal cancer cells. In keratinocytes, 14-3-3sigma (stratifin) is involved in terminal differentiation and its cell cycle function in this cell type might diverge from the one it fulfills in other cellular backgrounds.
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PMID:Radiation response and cell cycle regulation of p53 rescued malignant keratinocytes. 1612 Apr 40

14-3-3 sigma (sigma) is a negative regulator of the cell cycle and contributes to G2 arrest. Lack of its expression due to hypermethylation of CpG islands has been reported in some carcinomas. A recent study showed that 14-3-3 sigma was down-regulated through proteolysis by estrogen-responsive finger protein (Efp). Here, we investigated the expression of 14-3-3 sigma, hormone receptors, Efp and p53 in 86 cases of endometrial adenocarcinoma and 46 cases of normal or non-neoplastic endometria by means of immunohistochemistry and methylation-specific polymerase chain reaction. In normal endometrium, 14-3-3 sigma was overexpressed in the mid- to late-secretory phase due to hypomethylation. In endometrial adenocarcinoma, 14-3-3 sigma expression was low in low grade endometrioid adenocarcinoma due to hypermethylation, and increased significantly with increasing histological grade due to hypomethylation. 14-3-3 sigma expression inversely correlated with estrogen receptor alpha, progesterone receptor and Efp, and positively correlated with myometrial invasion and lymph node metastasis. These results suggest that 14-3-3 sigma was one of the menstrual cycle-related proteins regulated by epigenetic methylation, and its expression was influenced by epigenetic methylation or hormone receptors in progression of endometrial adenocarcinoma, and therefore was more than just a cell-cycle regulator.
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PMID:Increasing 14-3-3 sigma expression with declining estrogen receptor alpha and estrogen-responsive finger protein expression defines malignant progression of endometrial carcinoma. 1627 Oct 83


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