Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: HUMANGGP:015151 (p21)
 21,217 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies in our laboratory showed nonrandom losses of chromosome 3p in association with tumorigenic transformation of SV40-immortalized human uroepithelial cells (HUC) to high grade cancers. To test the hypothesis that genes on 3p suppress HUC tumorigenesis, somatic cell hybrids were formed between nontumorigenic SV40-immortalized HUC and an isogeneic derivative transitional cell carcinoma line, MC-T16, that lost 3p on initial transformation. All hybrids were initially tumorigenically suppressed and reversion was always associated with genetic losses, including losses of 3p (Klingelhutz et al., Somatic Cell Mol. Genet., 17: 551-565, 1991). In this paper, we report that the smallest 3p region lost in a tumorigenic hybrid revertant (THR-X) in this system was an unusual interstitial deletion of 3p13----p21.2. Restriction fragment length polymorphism analysis confirmed this loss by showing that THR-X was reduced to homozygosity for D3S30, a 3p13 probe, but remained heterozygous for the distal 3p21.3 probe, D3F15S2. These data, along with our previous report identifying loss of 3p13----p14.2 as the smallest 3p region deleted in association with SV40-immortalized HUC tumorigenic transformation (Klingelhutz et al., Genes Chromosomes Cancer, 3: 346-357, 1991), provide compelling new evidence for a bladder cancer suppressor gene in the 3p13----p21.2 region.
 ...
PMID:Loss of 3p13----p21.2 in tumorigenic reversion of a hybrid between isogeneic nontumorigenic and tumorigenic human uroepithelial cells. 131 37

Tumorigenic transformation of SV40-immortalized human uroepithelial cells (SV-HUC) after transfection with EJ/ras was previously reported to be a rare event. To test the hypothesis that ras transformation requires loss of suppressor genes, somatic cell hybrids were generated between a rare tumorigenic transformant and an isogeneic nontumorigenic EJ/ras transfectant obtained in the same experiment. Both parental cell lines, as well as all hybrid progeny, expressed mutant p21 ras protein, but injections of three such independent hybrids into athymic nude mice at passage (P) 4 demonstrated that tumorigenicity was suppressed at 20 of 22 sites. Two tumors developed, after a relatively long 17-week latent period, as compared with a 4-week latent period for the tumorigenic parent. All three hybrids produced tumors at P8, but these showed different latent periods (3-14 weeks). Revertant hybrid tumors were high-grade carcinomas. Cell lines derived from these tumors expressed mutant p21 ras and retained at least 1 EJ/ras integration site. Karyotypic analysis of six independent hybrid tumor revertants showed that each had a unique clonal karyotype. Losses of two or more homologues of 1p, 3p, 4, 8, 10p, 11p, 13q, and 18 were identified in one or more tumorigenic revertants. Losses of all these chromosomes were previously associated with transformation of SV-HUC by EJ/ras, but were also associated with chemical transformation of SV-HUC in tumors that did not express mutant ras. Genetic losses involving most of these chromosomes have also been identified in clinical bladder cancers (i.e., 1p, 3p, 8, 11p, 13 and 18q). These data show that expression of EJ/ras does not negate or significantly alter requirements for multiple genetic losses in HUC tumorigenesis.
 ...
PMID:Chromosome losses in tumorigenic revertants of EJ/ras-expressing somatic cell hybrids. 131 24

Human cyclin D1 has been associated with a wide variety of proliferative diseases but its biochemical role is unknown. In diploid fibroblasts we find that cyclin D1 is complexed with many other cellular proteins. Among them are protein kinase catalytic subunits CDK2, CDK4 (previously called PSK-J3), and CDK5 (also called PSSALRE). In addition, polypeptides of 21 kd and 36 kd are identified in association with cyclin D1. We show that the 36 kd protein is the proliferating cell nuclear antigen, PCNA. Cyclin D3 also associates with multiple protein kinases, p21 and PCNA. It is proposed that there exists a quaternary complex of D cyclin, CDK, PCNA, and p21 and that many combinatorial variations (cyclin D1, D3, CDK2, 4, and 5) may assemble in vivo. These findings link a human putative G1 cyclin that is associated with oncogenesis with a well-characterized DNA replication and repair factor.
 ...
PMID:D type cyclins associate with multiple protein kinases and the DNA replication and repair factor PCNA. 135 58

The animal models for chemoprevention of breast cancer have provided important experimental systems to evaluate the efficacy of tumor suppression by dietary macro- and micronutrients. In the initiation/promotion cascade, early occurring premalignant changes constitute less extensively examined aspects of disease progression. Molecular, endocrine and cellular biomarkers may provide clinically relevant endpoints for prevention of breast cancer that focus on downregulation of preneoplastic transformation. In vitro models derived from non-involved murine and human mammary tissues are utilized to identify molecular, endocrine and cellular markers that are perturbed in response to such diverse initiators as viruses and chemical carcinogens. This upregulation was manifested as persistent Ras p21-GTP binding, altered C16 alpha/C2 hydroxylation of estradiol, and hyperplasia preceding tumorigenesis. Prototypic chemopreventive agents such as n-3 polyunsaturated fatty acids, retinoids, and indole-3-carbinol were capable of downregulating all of the preneoplastic markers perturbed by initiators. Experimental modulation of these biomarkers in murine and human mammary tissue prior to the expression of a fully transformed tumorigenic phenotype is suggestive of their potential clinical application in chemopreventive intervention for breast cancer.
 ...
PMID:Molecular and endocrine biomarkers in non-involved breast: relevance to cancer chemoprevention. 146 96

We studied the ras oncogene expression using immunohistochemical detection of p21 oncoprotein in paraffin-embedded tissue sections or fine needle aspiration (FNA) material from 25 patients with Hashimoto's thyroiditis and 12 healthy individuals. We also investigated the presence of this protein in the lymphocytes of thyroid gland, as well as in peripheral blood lymphocytes. We found increased expression of p21 oncoprotein by thyroid epithelial cells in 22 patients (intensity of staining ++), whereas we observed negative or slightly positive in 9 and 3 out of 12 normal controls, respectively (intensity of staining, - or +/-). We also detected p21 oncoprotein in moderate amounts in patients' intrathyroid lymphocytes (intensity of staining +), but peripheral blood lymphocytes did not present any staining result. Our findings provided evidence that epithelial cells, as well as lymphocytes infiltrating the thyroid gland, are probably "activated" in Hashimoto's thyroiditis. The significance of this "activation" in thyroid tumorigenesis remains unknown.
 ...
PMID:Immunohistochemical analysis of the ras p21 oncoprotein in Hashimoto's thyroiditis. 150 8

We have investigated the expression of the products of two well-characterized oncogenes, erbB and Ha-ras, in the primary cultures of human gynecologic tumor cells by indirect immunofluorescent analysis. Epidermal growth factor receptor (c-erbB gene product) and p21 (ras gene product) were highly expressed in 21 out of 26 cases (81%) and 14 out of 18 cases (78%), respectively. Furthermore, they were frequently co-localized in the same region of the cells. These results suggest that these two oncogene products may play a part in gynecologic tumorigenesis and that they can interact with each other.
 ...
PMID:Expression and localization of epidermal growth factor receptors and ras oncogene products in gynecologic tumors. 161 23

The amplification and expression of the cellular oncogene c-Ki-ras have been detected in twelve tissue specimens of human ovarian adenocarcinoma, one ascites of ovarian cancer and ovarian cancer cell line NIH: OVCAR-3. Four out of the twelve cancer tissue specimens, one specimen of cancer ascites cells and the NIH: OVCAR-3 cancer cell line showed elevated amplification of c-Ki-ras, as compared to the human fibroblast cell line FS4 and normal ovarian tissues. The amplification of the c-Ki-ras gene showed some correlation with clinical stages of ovarian cancer. The levels of c-Ki-ras specific RNA transcripts and ras gene product p21 were also elevated in these four cancer tissue specimens. Surprisingly, a discrepancy between amplification and expression of c-Ki-ras was noted in five of the other eight cancer tissue specimens, in which enhanced expression of c-Ki-ras was present without the accompanying elevated amplification of c-Ki-ras. The results do provide some clues to understanding the possible mechanisms of tumorigenesis in human ovarian cancer.
 ...
PMID:Amplification and expression of c-Ki-ras oncogene in human ovarian cancer. 169 86

Specific and sensitive markers capable of determining the extent of tumorigenesis are important end points not only for evaluating the carcinogenic potency, but also for assessment of chemopreventive efficacy of modulators. Prototypic mammary carcinogens induce a high frequency of mammary adenocarcinomas. The appearance of tumors, however, is a culmination of initiational and promotional events whose modulation may constitute an effective means for chemopreventive interventions. The purpose of this study was i) to identify intermediate biomarkers for mammary cell transformation and ii) to apply these biomarkers and validate the ability of selected fatty acids to modulate chemical carcinogen-induced tumorigenic transformation. An in vitro model derived from mouse mammary explant cultures was utilized to examine the effects of 7,12 dimethylbenz (a) anthracene (DMBA), a prototype chemical carcinogen for rodent mammary gland. The effects of DMBA exposure were quantified at the molecular level by determining induction of oncogene expression, at metabolic level by determining the extent of estradiol metabolism, and at cellular level by determining the emergence of hormone-independent mammary alveolar lesions (MAL) and their tumorigenic potential. DMBA treatment induced binding of ras oncogene product ras p21 to [alpha 32P] GTP, altered estradiol metabolism by increasing the ratio of C16 alpha/C2 hydroxylation in favor of 16 alpha-OHE1 formation, and exhibited high frequency of MAL. Transplantation of cells from these MAL produced rapidly growing tumors. Treatment of DMBA-exposed cultures with polyunsaturated n-6 fatty acids enhanced, and treatment with polyunsaturated n-3 fatty acid suppressed the molecular, metabolic and cellular intermediate biomarkers for tumorigenic transformation. Thus, oncogene expression, estradiol metabolism and formation of MAL may constitute useful molecular, metabolic and cellular intermediate biomarkers. Alteration of these biomarkers by selected fatty acids is suggestive of their utility as end points for the chemopreventive efficacy of dietary agents.
 ...
PMID:Preneoplastic transformation in mouse mammary tissue: identification and validation of intermediate biomarkers for chemoprevention. 190 12

Histopathological examination of thymomas often fails to predict their malignant potential because the morphology of invasive or metastatic thymomas does not differ significantly from that of benign, encapsulated thymomas. In order to find a marker of aggressiveness in thymomas, 21 cases (9 non-invasive, 8 invasive and 4 metastatic thymomas) were examined for expression of the ras oncogene product p21 by immunohistochemistry and immunoblot analysis. Immunohistochemical study, using a serially diluted monoclonal antibody, NCC-RAS-001, demonstrated that neoplastic thymoma cells generally contained more p21 than normal thymic epithelial cells. Immunoblot analysis using another monoclonal antibody (NCC-RAS-004) also confirmed the increased concentration of p21 in all but one of the thymomas by comparison with normal thymic tissue. One metastatic thymoma did not have a band of p21 recognized by NCC-RAS-004 and was believed to have a deletion of the epitope recognized by this antibody. In addition, another metastatic thymoma showed abnormal electrophoretic mobility of p21. The increased amount of p21 in thymomas suggests that this protein has a role in the oncogenesis or progression of thymoma. The high incidence of a p21 molecular abnormality in metastatic thymomas indicates that the abnormality of this protein could be used as a possible marker of aggressive behavior.
 ...
PMID:Expression of ras p21 protein by thymoma. 197 93

Mutated ras genes are powerful transforming agents in vitro and are found in a wide variety of human tumors in vivo. We characterized the histopathology and p21 protein expression associated with tumorigenesis in line 69 transgenic mice carrying an activated, human c-Ha-ras gene on the Y-chromosome (A. C. Andres, C. A. Schonenberger, B. Groner, L. Hennighausen, M. LeMeur, and P. Gerlinger, Proc. Natl. Acad. Sci. USA, 84: 1299-1303, 1987). Male mice developed salivary and/or mammary gland tumors. The salivary tumors were adenosquamous carcinomas arising from serous areas of the submandibular gland. They characteristically exhibited densely packed cords and sheets of moderately anaplastic cells. Tumorigenic tissue had a high mitotic index, and all tumor-bearing animals had an ongoing inflammatory response as evidenced by extensive immune cell infiltration of affected tissue. Half of the mammary gland tumors were adenosquamous carcinomas with multiple foci of squamous metaplasia, while the rest were adenocarcinomas containing glandular tissue. Most tumors had a high mitotic index, and abnormal mitotic figures were common. All tumors produced p21 ras, as confirmed by immunohistochemistry and Western blots. Both tumor types expressed elevated levels of p21 protein. Microscopic lung metastases were present in 5 of 35 animals (14%). Our results suggest that this transgenic mouse will provide a useful model for testing therapies directed against ras-associated tumorigenesis.
 ...
PMID:Histopathology of salivary and mammary gland tumors in transgenic mice expressing a human Ha-ras oncogene. 206 30


1 2 3 4 5 6 7 8 9 10 Next >>