Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was concerned with expression of MMTV-related antigens in cells of stable MCF-7 and T47D lines of human breast cancer. Indirect immunoperoxidase technique using antisera against whole preparations of virus of RIII and C3H mice as well as certain MMTV proteins identified cells which express proteins cross-reactive with both gp52 and p27. MCF-7 sublines with a high level of positive cells were obtained. The stimulating effect of pregnancy and lactation hormones on MMTV-related proteins was studied.
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PMID:[Expression of antigens related to structural protein antigens of MMTV in breast cancer cells]. 241 Oct 55

The presence of antibodies to MuMTV-related proteins in sera of 31 mammary carcinoma patients' healthy daughters have been tested by indirect immunoperoxidase method (ELISA). Ten of them (32.3 +/- 8.4%) reacted with MuMTV proteins preparations, but not with MuLV, RaLV, SSV, MPMV proteins or preparations of mouse embryonic tissues. The percent of positive sera in this group is almost ten times higher than among women without breast cancer in family history (earlier published data). By immunoblotting method the specificity for five positive sera was determined. Two sera react with p27, one with p27 and to a less extent with gp52, one-only with gp52 and one more serum with both proteins equally. Mothers of the daughters with positive-reacted sera were characterized by premenopausal tumors, detected on early (I, IIa) clinical stage of disease.
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PMID:Antibodies to MuMTV proteins in the sera of mammary carcinoma patients' healthy daughters. 303 Feb 19

A highly sensitive electroimmunodiffusion method on cellulose acetate films, developed by Abelev on the basis of isotachoelectrophoresis, was applied to search of MuMTV-related antigenicity in tumor tissue and sera of breast cancer patients. In 2 out of 5 breast cancer extracts, protein fractions corresponding to a molecular weight of about 50,000 daltons were seen to exhibit antigenicity related to the major core antigen of MuMTV (p27). This antigenicity could not be detected in the sera of the patients.
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PMID:Use of an electroimmunodiffusion method on cellulose acetate films for the detection of antigenicity in human breast cancers that is related to the major core antigen of mouse mammary tumor virus (MuMTV). 627 67

The human p27kip1 gene encodes a cyclin-dependent kinase inhibitor implicated in the negative regulation of the cell cycle. In order to elucidate the possible role of p27 mutations in the development or progression of human breast cancer, we have studied the occurrence of genetic abnormalities in this gene in a series of 30 primary breast carcinomas. Direct sequence analysis of the polymerase chain reaction amplified human p27 gene revealed the occurrence of two sequence variations with respect to the reported sequence; both variants were also present in the lymphocyte DNA from the same patients. First, a silent G to A change at codon 142 (Thr) was detected in a single case. Second, a T to G transversion at codon 109, resulting in a Val to Gly change, was observed in eight tumour DNA samples (26%) and in 31 out of 80 unrelated normal individuals (39%). This latter change creates a Bg/I restriction site that might be useful for genetic analysis of human tumours. Despite the occurrence of these polymorphisms, we did not however find any evidence of somatic mutations in the coding region of the p27 gene. On the basis of these results, we suggest that alterations in the integrity of the human p27 gene are not common events in human breast carcinomas.
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PMID:Mutational analysis of the human cyclin-dependent kinase inhibitor p27kip1 in primary breast carcinomas. 855 69

The p27/Kip1 protein belongs to the recently identified family of proteins called cyclin-dependent kinase inhibitors. These proteins play an important role as negative regulators of cell cycle-dependent kinase activity during progression of the cell cycle. Since cyclin-dependent kinase inhibitors can inhibit cell proliferation, they may have a role as tumor suppressor genes. To determine whether p27 alterations may be involved in tumorigenesis, we examined its mutational status in 36 primary breast carcinomas and 9 breast cancer cell lines using PCR-single-strand conformational polymorphism, direct DNA sequencing, and Southern blot analysis. Southern blot analysis showed no homozygous deletions of the p27 gene in either the clinical samples or cell lines. Two point mutations were found in primary tumors. One represents a previously undescribed polymorphism at codon 142; another is a nonsense mutation at codon 104. The latter mutation was absent in the normal matched control sample, and, in addition, it was accompanied with the loss of heterozygosity (LOH) of a microsatellite marker in the vicinity of the p27 gene on chromosome 12p13. These data indicate that p27 mutations are a rare event in breast cancer, but may play an important role in the development of a minority of these cancers. Furthermore, LOH analysis of the 12p13 locus revealed that an additional four of six matched DNA samples had LOH at 12p13 but did not have an alteration of the p27 gene, suggesting that another tumor suppressor gene is located on the short arm of human chromosome 12 which may be frequently involved in the pathogenesis of breast cancers.
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PMID:p27/Kip1 mutation found in breast cancer. 862 18

Cyclin-dependent kinase inhibitors (CKIs) p21, p27, p16, and p15 are an essential and integral part of cell cycle regulation. Studies on the expression of these inhibitors in normal versus tumor human breast cancer cells revealed that although p27 and p16 are expressed at higher levels in tumor cells, p21 and p15 expression were higher in normal cells. Analysis on the expression pattern of these proteins throughout the cell cycle in synchronized cells demonstrated a substantial increase in p21 during the S-phase in normal cells and barely detectable expression of p21 in any phase of the tumor cell cycle. Levels of p15, p16, and p27 remained relatively constant throughout the cell cycle of normal and tumor cells. Synchronization of tumor cells by lovastatin, which arrests cells in G1, resulted in increased levels of p21 and p27 with a concomitant decrease in cyclin-dependent kinase 2-associated kinase activity. Synchronization of cells by double-thymidine block did not result in the induction of p21 or p27. These observations suggest that lovastatin causes a profound cell cycle-independent alteration of CKI expression which is distinct from growth factor deprivation or thymidine block.
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PMID:Lovastatin induction of cyclin-dependent kinase inhibitors in human breast cells occurs in a cell cycle-independent fashion. 904 34

Estrogens induce cell proliferation in target tissues by stimulating progression through G1 phase of the cell cycle, but the underlying molecular targets remain undefined. To determine the role of the cyclin/cyclin-dependent kinase (CDK)/retinoblastoma protein (pRB) pathway in this response we treated MCF-7 breast cancer cells with the pure estrogen antagonist ICI 182780 to inhibit estrogen-induced gene expression and induce G1 phase arrest. Subsequent treatment with 17beta-estradiol resulted in the synchronous entry of cells into S phase commencing at 12 h. The proportion of cells in S phase reached a maximum of 60% at 21-24 h. Cells subsequently completed mitosis and entered a second semisynchronous round of replication. Entry into S phase was preceded by increased activity of both Cdk4 and cyclin E-Cdk2 and hyperphosphorylation of pRB, all within the first 3-6 h of estradiol treatment. The increase in Cdk4 activity was accompanied by increases in cyclin D1 mRNA and protein, indicating that an initiating event in the activation of Cdk4 was increased cyclin D1 gene expression. In contrast, the levels of Cdk2 and the CDK inhibitors p21 (WAF1/CIP1/SDI1) and p27 (KIP1) in total cell lysates and in cyclin E immunoprecipitates were unaltered at these early time points. However, an inhibitory activity was present in antiestrogen-pretreated cell lysates toward recombinant cyclin E-Cdk2 and was relieved by estradiol treatment. This activity was attributable predominantly to p21. These apparently conflicting data were resolved by performing gel filtration chromatography, which revealed that only a minority of cyclin E-Cdk2 complexes were active following estradiol treatment. Active complexes eluted at a higher molecular weight than inactive complexes, were relatively deficient in both p21 and p27, and contained Cdk2 with increased threonine 160 phosphorylation, consistent with a mechanism of activation of cyclin E-Cdk2 involving both reduced CDK inhibitor association and CDK-activating kinase-mediated phosphorylation of Cdk2. These results provide an explanation for the early activation of both cyclin D1-Cdk4 and cyclin E-Cdk2 complexes that accompany G1-S phase progression in response to estradiol.
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PMID:Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2. 909 45

The expression of cyclin-dependent kinase inhibitor p27(kip1) in human tumors and normal tissues was investigated using a panel of novel anti-p27(kip1) mAbs. An inverse correlation between expression of p27(kip1) and cell proliferation was generally observed after analyzing its expression in 25 different normal human tissues. In some highly proliferative human breast cancer cells, however, high level p27(kip1) expression was seen, indicating the existence of a mechanism by which some growing tumor cells may tolerate this inhibitor of cell cycle progression. Detailed studies demonstrated a correlation between the high level expression of p27(kip1) and cyclin D1 in human breast cancer cells. There was also an inverse correlation between the expression of p27(kip1) and the degree of tumor malignancy in human breast and colorectal cancers, indicating that p27(kip1) may be a useful prognostic marker in these cancers.
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PMID:High level expression of p27(kip1) and cyclin D1 in some human breast cancer cells: inverse correlation between the expression of p27(kip1) and degree of malignancy in human breast and colorectal cancers. 917 26

In order to elucidate the biochemical mechanisms by which the universal cyclin kinase inhibitor p27Kip1 regulates cell cycle progression in human breast cancer cells, a recombinant adenovirus expressing human p27 was constructed (Adp27). Upon infection of human breast cancer cells MDA-MB-231 and MCF-7 with Adp27, a high level of p27 expression was observed, and this resulted in a marked decrease in the proportion of cells in S-phase. In multiple cell lines, comparison of the cytotoxicity of Adp27 with another adenovirus vector expressing the related universal cyclin kinase inhibitor WAF1/Cip1 (AdWAF1), showed Adp27 to be markedly more (up to 56-fold) toxic than AdWAF1. DNA histograms showed Adp27 to cause a G1/S arrest at lower viral doses than AdWAF1. Analysis of cyclin dependent kinase activity following Adp27 infections showed decreased Cdk2 and cyclin B1-Cdc2 activity at lower viral doses when compared with AdWAF1. Adp27 is therefore potentially useful for studies of growth regulation and for gene therapy when growth inhibition is desired.
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PMID:A recombinant adenovirus expressing p27Kip1 induces cell cycle arrest and loss of cyclin-Cdk activity in human breast cancer cells. 917 4

Retinoids mediate the normal growth of a variety of epithelial cells and may play an important role in the chemoprevention of certain malignancies. Loss of retinoic acid (RA) receptor-beta function may be an important event in mammary carcinogenesis, because the majority of breast cancers, in contrast to normal mammary epithelial cells, fail to express this receptor. We previously reported that all-trans-RA mediates G1 arrest as well as apoptosis in certain RAR beta-transduced breast cancer cell lines. We now report the effect of RA on normal human mammary epithelial cells (HMECs), which express functionally active retinoid receptors. We observe that RA induces growth suppression and G1 arrest of these HMECs but find no evidence that RA mediates apoptosis in these normal cell strains. This RA-induced G1 arrest is temporally associated with decreased levels of hyperphosphorylated retinoblastoma protein without any significant changes in c-myc, p53, p21, or p27 expression. Expression of cyclin D1, cyclin-dependent kinase 4, and cyclin E proteins, however, decreased in association with RA-mediated G1 arrest. Our studies suggest that growth inhibition, rather than apoptosis, may be a mechanism by which RA and RA receptors act to prevent the malignant transformation of normal mammary epithelial cells. The molecular target(s) of the activated RA receptors that mediate this G1 arrest in HMECs appear to be associated with a retinoblastoma-dependent pathway.
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PMID:All-trans-retinoic acid mediates G1 arrest but not apoptosis of normal human mammary epithelial cells. 918 97


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