Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Progestin antagonists inhibit the proliferation of progesterone receptor-positive cells, including breast cancer cells, by G1 phase-specific actions, but the molecular targets involved are not defined. Reduced phosphorylation of pRB, a substrate for G1 cyclin-dependent kinases (CDKs) in vivo, was apparent after 9 h treatment of T-47D breast cancer cells with the antiprogestins RU 486 or ORG 31710, accompanying changes in S phase fraction. Although the abundance of cyclin D1, Cdk4, and Cdk6 did not decrease cyclin D1-associated kinase activity was reduced by approximately 50% at 9-18 h. Similarly, cyclin E-associated kinase activity decreased by approximately 60% at 12-24 h in the absence of significant changes in the abundance of cyclin E and Cdk2. The CDK inhibitor p21 increased in mRNA and protein abundance and was present at increased levels in cyclin D1 and cyclin E complexes at times when their kinase activity was decreased. Increased p21 protein abundance was observed in another antiprogestin-sensitive cell line, BT 474, but not in two breast cancer cell lines insensitive to antiprogestins. These data suggest increased p21 abundance and concurrent inhibition of CDK activity as a mechanism for antiprogestin induction of growth arrest. Antiprogestin effects on proliferation were markedly reduced after ectopic expression of cyclin D1, indicating that inhibition of cyclin D1 function is a critical element in antiprogestin inhibition of proliferation. However, these data also implicate regulation of cyclin E function in antiprogestin regulation of cell cycle progression.
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PMID:Antiprogestin inhibition of cell cycle progression in T-47D breast cancer cells is accompanied by induction of the cyclin-dependent kinase inhibitor p21. 899 88

The human progesterone receptor (hPR) in T47D breast cancer cells is phosphorylated on at least nine different serine residues. We have previously reported the identification of five sites; three are hormone inducible (Ser102, Ser294 and Ser345), and their phosphorylation correlates with the timing of the change in receptor mobility on gel electrophoresis in response to hormone treatment. The other two sites, Ser81 and Ser162, along with the remaining sites, are basally phosphorylated and exhibit a general increase in phosphorylation in response to hormone. With the exception of Ser81, all of these sites are in Ser-Pro motifs, suggesting that proline-directed kinases are responsible for their phosphorylation. We now report that cyclin A-cyclin-dependent kinase-2 complexes phosphorylate hPR-B in vitro with a high stoichiometry on three sites that are authentic basal sites in vivo. One of these is Ser162, which has been described previously. The other two sites are identified here as Ser190 and Ser400. The specificity and stoichiometry of the in vitro phosphorylation suggest that hPR phosphorylation may be regulated in a cell cycle-dependent manner in vivo.
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PMID:Phosphorylation of human progesterone receptor by cyclin-dependent kinase 2 on three sites that are authentic basal phosphorylation sites in vivo. 917 Dec 45

We studied the immunolocalization of cyclins D1 and E and their corresponding partner cyclin dependent kinases (cdk), cdk4 and cdk2 in 41 cases of human breast malignancy (21 invasive ductal carcinomas and 19 invasive lobular carcinomas) and examined the correlation of the labeling indexes among these cyclins, cdks, Ki67, estrogen receptor (ER) and progesterone receptor (PR). Cyclin D1 immunoreactivity was observed exclusively in the nuclei of tumor cells in 27/41 (65%) of the cases examined. Immunoreactivity for cyclin E and cdk2 was detected in all the cases and observed in the nuclei of both carcinoma and non-carcinoma cells. cdk4 immunoreactivity was detected in 39/41 (95%) cases and found in carcinoma and non-carcinoma cells. In all carcinomas examined, a significant correlation was observed only between Ki67 and cyclin D1 (p = 0.0037). However, when examining only invasive ductal carcinomas, a significant correlation was detected between Ki67 and cyclin D1 (p = 0.0069), Ki67 and cdk2 (p = 0.0043) and cyclin D1 and cdk4 (P = 0.0024). Only cyclin D1 correlated with the pathologic stages of the disease and histological grades of invasive ductal carcinoma. Among these cyclins and cdk, overexpression of cyclin D1 is considered to play an important role in the development of human breast malignancy through abnormal proliferation. No significant correlation was observed between steroid receptor status and any of cyclins and cdks examined. Cyclin D1 and cdk2 expression correlated with cell proliferation (Ki67) and cyclin D1 expression with expression of cdk4 in invasive ductal carcinoma but not invasive lobular carcinoma. Cyclin E expression did not correlate with cell proliferation, cyclin D1 or cdks possibly due to deregulation of its expression. These results also indicate different patterns of cyclin D1, cyclin E, cdk2 and cdk4 expression between invasive ductal and lobular carcinoma of human breast.
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PMID:Immunolocalization of cyclins D and E and cyclin dependent kinase (cdk) 2 and 4 in human breast carcinoma. 941 24

p27Kip1 is a member of the Cip/Kip family of cyclin-dependent kinase inhibitors. It binds to a variety of cyclin/CDK complexes, inhibits kinase activity, and blocks the cell cycle. Absent or reduced p27 expression has been shown to be a significant predictor of poor survival in breast, colorectal, prostate, non-small cell lung and esophagus carcinomas. An immunohistochemical assay was performed on 169 patients with primary breast cancers to evaluate the biologic significance of p27 expression. Decreased p27 expression was significantly associated with high grade (P = 0.00025), negative estrogen receptor (P = 0.00004), and negative progesterone receptor (P = 0.0038) breast cancers. Univariate analysis reveals that p27 expression inversely correlated significantly with overall survival (P = 0.0001). By multivariate analysis, p27 predicted the overall survival independently (P = 0.0096). Our study indicates that p27 expression is an independent prognostic marker of breast cancer in Taiwan.
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PMID:p27 expression as a prognostic factor of breast cancer in Taiwan. 1045 52

The search for better prognostic indicators and new treatment modalities in node-negative breast carcinoma patients is important. The aim of this study was to determine the immunohistochemical expression of central cell regulator proteins in relation to hormone receptor status, tumour-cell differentiation and prognosis. We investigated the immunoreactivity of p27, p21, cdk4, cyclin D1 and p53 in 77 node-negative breast carcinomas, with long-term follow-up (mean 163 months; range 20-227). Nuclear staining for p27 was seen in 87% of the carcinomas, for cdk4 in 92%, for p21 in 68%, for cyclin D1 in 58% and for p53 in 18%. Oestrogen receptor (ER) and progesterone receptor (PgR) nuclear staining was seen in 69% and 65% of the tumours, respectively. No correlation between the levels of p21 and p53 was observed. p21 overexpression was, however, associated with positive ER status. Elevated levels of p27 and cyclin D1 correlated with positive hormone status (both ER and PgR). We did find a significant correlation between p27 and cyclin D1 and histological grade of the tumours, with extensive positive immunostaining of p27 and cyclin D1 in well-differentiated carcinomas. The only significant prognostic factor in our series was histological grading. Ten-year relapse-free survival was significantly prolonged in patients with histological grade I tumours versus histological grade II and III tumours. Our results suggest that the expression of p27 and cyclin D1 is closely linked to hormone receptor status in breast carcinomas and to tumour differentiation, a finding that may be of importance in the treatment of hormone-dependent tumours.
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PMID:Elevated levels of p27, p21 and cyclin D1 correlate with positive oestrogen and progesterone receptor status in node-negative breast carcinoma patients. 1059 10

BACKGROUND: Prognostic factors for predicting the recurrence of node-negativebreast cancers have been controversial. The present study was performed to elucidate practically useful prognostic factors using formalin-fixed paraffin sections. METHODS: This was a case-controlled multi-institutional study that composed 40 patients with recurrent node-negative breast cancer and 80 patients with node-negative breast cancer but without recurrence after radical surgery. Tumors weresmaller than 3 cm in diameter and were treated surgically between January 1, 1985 and December 31, 1990. The recurrent and non-recurrent cases were matched with regard to their age, adjuvant chemotherapy and the year in which surgery was performed. Fourteen immunohistochemical factors and 8 histological factors of theprimary tumor were studied on formalin-fixed, paraffin-embedded sections by immunohistochemical and histochemical analyses. RESULTS: According to univariate analysis, factors such as progesterone receptor (PgR), MIB-1, CD44v6, CD44v9 and platelet-derived endothelial cell growth factor (PDECGF) were significantly different between the recurrent and non-recurrent groups (p &ly; 0.1; Wilcoxon-Mann-Whitney analysis). Chi-squared test showed significant differences in MIB-1, cdc2 and stromal plasminogen activator receptor (suPAR). Histologically, mitotic count was also significantly different between the two groups (p < 0.005). Multivariate analysis revealed that positivity for cdc2 (p=0.01), high mitotic count (p=0.04) and negativity for CD44v9 (p=0.02)were independent prognostic factors among variables selected by univariate analysis, and that positivity for MIB-1 (p=0.03) and cdc2 (p =0.01), and negativity for CD44v9 (p =0.03) were independent prognostic factors among the immunohistochemical markers examined. CONCLUSION: Our results indicated that positivity for MIB-1 and cdc2, high mitotic count and negativity for CD44v9 could serve as independent factors for predicting the recurrence of node-negative breast cancer.
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PMID:Prognostic Factors for Node-negative Breast Cancers: Results of a Study Program by the Japanese Breast Cancer Society. 1109 54

We have previously reported the identification of seven in vivo phosphorylation sites in the amino-terminal region of the human progesterone receptor (PR). From our previous in vivo studies, it was evident that several phosphopeptides remained unidentified. In particular, we wished to determine whether human PR contains a phosphorylation site in the hinge region, as do other steroid receptors including chicken PR, human androgen receptor, and mouse estrogen receptor. Previously, problematic trypsin cleavage sites hampered our ability to detect phosphorylation sites in large incomplete tryptic peptides. Using a combination of mass spectrometry and in vitro phosphorylation, we have identified six previously unidentified phosphorylation sites in human PR. Using nanoelectrospray ionization mass spectrometry, we have identified two new in vivo phosphorylation sites, Ser(20) and Ser(676), in baculovirus-expressed human PR. Ser(676) is analogous to the hinge site identified in other steroid receptors. Additionally, precursor ion scans identified another phosphopeptide that contains Ser(130)-Pro(131), a likely candidate for phosphorylation. In vitro phosphorylation of PR with Cdk2 has revealed five additional in vitro Cdk2 phosphorylation sites: Ser(25), Ser(213), Thr(430), Ser(554), and Ser(676). At least two of these, Ser(213) and Ser(676), are authentic in vivo sites. We confirmed the presence of the Cdk2-phosphorylated peptide containing Ser(213) in PR from in vivo labeled T47D cells, indicating that this is an in vivo site. Our combined studies indicate that most, if not all, of the Ser-Pro motifs in human PR are sites for phosphorylation. Taken together, these data indicate that the phosphorylation of PR is highly complex, with at least 14 phosphorylation sites.
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PMID:Identification of a phosphorylation site in the hinge region of the human progesterone receptor and additional amino-terminal phosphorylation sites. 1111 Aug 1

TGF-beta1 modulation of cell cycle components was assessed in an experimental model in which the synthetic progestin medroxyprogesterone acetate (MPA) induced mammary tumors in Balb/c mice. TGF-beta1 inhibited both MPA-induced proliferation of progestin-dependent C4HD epithelial cells and proliferation of the progestin-independent variant cell type C4HI, arresting cells in G(1) phase of the cell cycle. Progestin-independent 60 epithelial cells evidenced reduced response to TGF-beta1 antiproliferative effects. TGF-beta1 inhibition of cyclins D1 and A expression and up-regulation of p21(CIP1) levels were the common findings in all three cell types. In addition, a significant content reduction of cyclin D1/cdk4 and cyclin A/cdk2 complexes was found after TGF-beta1 inhibition of MPA-dependent and -independent proliferation. TGF-beta1 inhibited cyclin D2 expression and up-regulated p27(KIP1) levels only when acting as inhibitor of MPA-induced proliferation of C4HD cells. Regulation of these two cell cycle components resulted in decreased cyclin D2/cdk2 complex and in increased p27(KIP1) association with cdk2 in C4HD cells treated with TGF-beta1. These two molecular mechanisms, unobserved in progestin-independent growth of C4HI or 60 cells, were associated with a significantly higher degree of inhibition of cdk2 kinase activity in C4HD cells compared to that found in TGF-beta-treated C4HI or 60 cells. Reduced sensitivity of 60 cells to the growth-inhibitory effects of TGF-beta1 correlated with significantly lower levels of p15(INK4B), p21(CIP1), and p27(KIP1) expressed in these cells, compared to the levels present in C4HD or C4HI cells, and correlated as well with lack of expression of p16(INK4). Thus, common targets were found to exist in TGF-beta1 inhibitory action on breast cancer cells, but regulation of specific targets was found when TGF-beta1-inhibited proliferation driven by the progesterone receptor.
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PMID:Mechanisms of cell cycle arrest in response to TGF-beta in progestin-dependent and -independent growth of mammary tumors. 1128 53

The effects of the soybean isoflavone genistein and a commercially-available isoflavone-containing soy extract on the growth of F3II mouse mammary adenocarcinoma cells were investigated. Female Balb/c mice injected (s.c.) with F3II cells and fed diets supplemented with 0.6% soy extract (containing genistein at 750 ppm) exhibited a significant 90% reduction in tumor weight compared to controls, whereas female mice fed diets supplemented with 750 ppm genistein alone exhibited a significant 40% reduction in tumor weight compared to controls. Tumor samples from animals fed the 0.6% soy extract, but not from those animals fed the 750 ppm genistein diet alone, exhibited significantly higher protein levels of the cyclin-dependent kinase inhibitor p21(waf1/cip1) compared to controls. Neither of the two experimental diets altered tumor estrogen receptor-alpha or progesterone receptor protein levels. In vitro, genistein significantly inhibited F3II cell proliferation (IC(50) approximately 2-3 microM) and caused a G2/M block in cell cycle progression at concentrations as low as 5 microM. This genistein-induced G2/M arrest in vitro was associated with a significant increase in the protein expression of phosphorylated p34(cdc2) and of cyclin B1. These results indicate that genistein is an inhibitor of F3II mouse mammary adenocarcinoma cell growth in vivo and in vitro, in part due to its effect on specific cell cycle regulatory proteins. In addition, genistein fed to mice as part of the soy extract resulted in a greater magnitude of inhibition of mouse mammary adenocarcinoma tumor growth, compared to tumor growth of animals fed an equivalent amount of genistein alone. This suggests that genistein along with other constituent(s) in the soy extract may also contribute to suppression of F3II tumor growth.
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PMID:Soy extract inhibits mammary adenocarcinoma growth in a syngeneic mouse model. 1266 77

Our studies examining the role of the cell cycle-regulated kinase cyclin A/Cdk2 in progesterone receptor (PR) action have demonstrated that cyclin-dependent kinase activity is required for PR function and that cyclin A/Cdk2 functions as a PR coactivator. Although Cdk2 can phosphorylate PR, elimination of these phosphorylation sites has little effect on the ability of cyclin A/Cdk2 to stimulate PR activity. PR interacts with cyclin A and recruits cyclin A/Cdk2 to progestin-responsive promoters, stimulating transcription. Inhibition of Cdk2 activity abolishes progesterone-dependent activation of PR target genes in part through inhibition of PR-dependent recruitment of steroid receptor coactivator 1 (SRC-1) and subsequent histone H4 acetylation at the target promoter. In vitro studies revealed that the interaction between SRC-1 and PR is dependent upon phosphorylation of SRC-1. This heretofore-unknown mechanism provides a potential means for integrating the regulation of PR activity with cell cycle progression. Moreover, the ability of PR to recruit cyclin A/Cdk2 to target promoters provides locally elevated levels of kinase, which can preferentially facilitate phosphorylation-dependent interactions and enzymatic activities of coactivators at the target promoter.
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PMID:Cyclin-dependent kinase activity is required for progesterone receptor function: novel role for cyclin A/Cdk2 as a progesterone receptor coactivator. 1560 48


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