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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined tyrosine kinase activity of epidermal growth factor (EGF) receptor in a total of 34 human gastric carcinomas as well as in non-neoplastic gastric mucosa from the same patients. EGF receptor kinase activity of the carcinoma tissues and the non-neoplastic mucosa were 1.28 +/- 1.00 (Mean +/- S.E.) and 0.16 +/- 0.04 respectively, if the EGF receptor kinase activity of human placenta is 10. Twenty-one (62%) carcinoma tissues showed higher EGF receptor kinase activity than corresponding non-neoplastic mucosa, while in 6 cases (18%) the kinase activity was higher in the non-neoplastic mucosa than in the tumor tissues. No obvious correlation was observed between the increased kinase activity in the tumors and histological type or tumor staging. One tumor showed extremely high receptor kinase activity with ERBB gene amplification. This tumor showed strong immunoreactivity to EGF itself.
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PMID:Tyrosine kinase activity of epidermal growth factor receptor in human gastric carcinomas. 159 97

Transforming growth factor-alpha-Pseudomonas exotoxin-40 (TP40) is a recombinant fusion protein. TP40 consists of the entire human transforming growth factor-alpha (TGF alpha) protein fused to a 40,000 Da. segment of the Pseudomonas exotoxin A protein. TP40 is a bifunctional molecule that possesses the epidermal growth factor (EGF) receptor binding properties of TGF alpha and the cell killing properties of Pseudomonas exotoxin A. These properties make TP40 a selective cytotoxic agent that kills EGF receptor bearing cells. TP40 has been shown to effectively kill human tumor cell lines that possess EGF receptors in vitro and in nude mice. In the present study, TP40 was tested against tumors taken directly from patients and grown in a soft agar human tumor cloning system. A total of 107 patients' tumors (taken from patients with tumors refractory to chemotherapy) were tested with a continuous exposure to 0.5-50 nM concentrations of the agent. TP40 exhibited a clear dose response effect against a wide variety of human solid tumor colony-forming units with greater than or equal to 84% of evaluable tumors responding at a drug concentration greater than or equal to 24 nM. When used as a continuous exposure, concentrations of TP40 as low as 5 nM demonstrated substantial in vitro activity. This activity included cytotoxicity against breast, colorectal, endometrial, head and neck, non small-cell lung, gastric, sarcoma, and pancreatic cancer tumor colony-forming units. Additional in vivo testing of this compound is warranted.
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PMID:Activity of a recombinant transforming growth factor-alpha-Pseudomonas exotoxin hybrid protein against primary human tumor colony-forming units. 160 49

The gene for the epidermal growth factor (EGF) receptor is amplified in a variety of neoplastic tissues, including malignant gliomas. To reveal whether increased sensitivity to EGF has significance for the supply of metabolic substrate to tumor cells, the rate of glucose transport was determined in cells exposed to EGF for up to six hours. In the epidermoid carcinoma line A431, and in primary cultures from 7/12 human glioma biopsies, EGF (10 ng/ml) induced an increase (two-fold) in glucose transport. This effect was transient and independent of protein synthesis.
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PMID:Epidermal growth factor induces glucose transport in primary cell cultures derived from human astrocytic glioma biopsies. 160 38

The c-myc proto-oncogene was analyzed in 311 cases of primary breast cancer, in 8% of which it was found to be amplified, usually at moderately increased copy number (2-5 copies). The adjacent pvt gene was co-amplified with c-myc in all tumors analyzed. C-myc amplification was significantly correlated to a high S-phase fraction and to amplification of the c-erbB-2 proto-oncogene. Weak relationships were found between c-myc amplification and the presence of lymph-node metastasis, advanced stage, DNA non-diploidy and premenopausal status, but not tumor size, estrogen receptor or progesterone receptor status, or int-2 amplification. C-myc amplification, and especially a high gene copy number (greater than 5 copies), was significantly related to early recurrence and death in breast cancer, a relationship seen in both the lymph-node-negative and node-positive subcategories. A particularly strong correlation with poor clinical outcome was seen in postmenopausal patients (p greater than 0.0005), an association which persisted in multivariate survival analysis. We conclude that the activation of c-myc is indeed associated with rapidly growing and progressive breast cancer. Gene amplification, on the other hand, is relatively infrequent and occurs mostly at low copy number, implying that tumors are heterogeneous with respect to cell clones harboring c-myc amplification. An immunohistochemical assessment would more accurately illustrate the importance of c-myc activation in human breast cancer. However, the obvious instability of the c-myc transcript and translate suggests that c-myc is not a suitable prognostic marker for routine purposes.
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PMID:c-myc amplification is an independent prognostic factor in postmenopausal breast cancer. 161 75

In order to verify whether the HER-2/neu gene is involved in the initial phases of neoplastic disease or in its progression, we evaluated the amplification and overexpression of this gene in the primary tumor and in synchronous metastatic axillary lymph nodes of 26 women with operable breast cancer. HER-2/neu was amplified in 35% and overexpressed in 33% of the primary sites; similar percentages were found in lymph nodes. The clear correlation between the two disease sites regarding gene, mRNA and protein levels, supports the hypothesis that this gene is involved in the initial and invasive phases of neoplasia. Its actual role with respect to other biological tumor characteristics during the metastatic process should be investigated further.
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PMID:HER-2/neu gene in primary and local metastatic axillary lymph nodes in human breast tumors. 163 21

Prognostic predictors for node-negative breast carcinoma have not been clearly established. Immunostaining with Ki-67 antibody was performed on frozen sections of histologically proved node-negative breast carcinomas from 42 patients to examine its prognostic value and its association with other clinicopathologic and biochemical parameters, i.e., patient age and tumor size, histologic type, nuclear grade, mitotic rate, presence of vascular or lymphatic invasion, DNA ploidy, percentage of cells in S-phase, estrogen content, and c-erbB-2 amplification. Thirty-seven of the 42 tumors showed immunoreactivity with Ki-67 antibody in 1% to 55% of the tumor cells. A strongly significant correlation was observed between Ki-67 staining percentage and, respectively, nuclear grade, age, and mitotic rate. Nuclear grade 1 (the most anaplastic) tumors showed a significantly higher median percentage of cells stained (median, 14; range, 3 to 40) compared with nuclear grade 3 tumors (median, 0.5; range, 0 to 8). Thirteen patients developed recurrence; six of them died of disease. On univariate analysis, both 5-year disease-free and overall survivals were strongly associated with percentage of cells stained with Ki-67 antibody. Our results suggest that Ki-67 immunostaining correlates well with nuclear grade and clinical outcome in node-negative breast carcinoma. Because of small sample size analyzed in this study we were unable to do multivariate analysis. Therefore, further studies with larger number of cases are needed to determine whether tumor proliferative activity determined by Ki-67 immunostaining is an independent prognostic parameter or it merely reflects histopathologic features such as nuclear grade or mitotic activity.
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PMID:Ki-67 immunostaining in node-negative stage I/II breast carcinoma. Significant correlation with prognosis. 164 33

From a single spontaneous feline mammary carcinoma, two subpopulations of epithelial tumor cells have been isolated. The variant cells were established as cell lines designated K248C and K248P. DNA ploidy analysis showed that the two cell lines represented cell populations already present in the original tumor. Chromosome analysis confirmed the feline origin of K248C and K248P and demonstrated that in addition to unique marker chromosomes characteristic for each cell line, both cell lines had several marker chromosomes in common. These data suggest that the two cell populations arose from a hypothetical single ancestor which diverged during tumor progression. The K248C and K248P cell lines differed from one another with respect to their tumorigenicity in athymic mice and epidermal growth factor (EGF) receptor content. The K248C cells were highly tumorigenic as indicated by a short latency period and high take rate. The K248P cells were poorly tumorigenic. Southern blot analysis revealed that the K248C cells contained an amplified EGF receptor gene that was accompanied by elevated levels of EGF receptor RNA and protein. The K248C cells were growth inhibited in vitro at EGF concentrations that stimulated growth of K248P cells. The amplification of the EGF receptor gene could be detected only in DNA derived from K248C cells at high passage numbers and not in DNA derived from the original tumor and K248C cells at low passage numbers. These data suggest that amplification of the EGF receptor gene occurred during establishment of the K248C cell line.
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PMID:Isolation of two distinct epithelial cell lines from a single feline mammary carcinoma with different tumorigenic potential in nude mice and expressing different levels of epidermal growth factor receptors. 164 97

Many human tumors of epithelial origin contain cells overexpressing the epidermal growth factor (EGF) receptor, and there is convincing evidence that cancer cell growth is correlated with the loss of the normal regulation of the EGF receptor signal transduction pathway. Some cancers are clearly dependent on activation of the EGF receptor for their proliferation. Recently, a class of compounds, tyrphostins, which inhibit the protein tyrosine kinase activity of the growth factor receptor, have been described. In this report, we have examined the antiproliferative effects of potent new tyrphostins on a well-characterized human squamous cell carcinoma in vitro and in vivo. We found that two of these compounds (RG-13022 and RG-14620) suppressed not only EGF-stimulated cancer cell proliferation in vitro but also tumor growth in nude mice. RG-13022 also increased the life span of these tumor-bearing nude mice. When administered to tumor-bearing nude mice together with monoclonal antibodies to the EGF receptor at a suboptimal dose which had no effect alone, inhibition of tumor growth was markedly enhanced. These data suggest that tyrphostins have potential as anticancer agents.
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PMID:The antiproliferative effects of tyrosine kinase inhibitors tyrphostins on a human squamous cell carcinoma in vitro and in nude mice. 165 Nov 59

A growth factor-stimulated protein kinase activity that phosphorylates the epidermal growth factor (EGF) receptor at Thr669 has been described (Countaway, J. L., Northwood, I. C., and Davis, R. J. (1989) J. Biol. Chem. 264, 10828-10835). Anion-exchange chromatography demonstrated that this protein kinase activity was accounted for by two enzymes. The first peak of activity eluted from the column corresponded to the microtubule-associated protein 2 (MAP2) kinase. However, the second peak of activity was found to be a distinct enzyme. We present here the purification of this enzyme from human tumor KB cells by sequential ion-exchange chromatography. The isolated protein kinase was identified as a 46-kDa protein by polyacrylamide gel electrophoresis and silver staining. Gel filtration chromatography demonstrated that the enzyme was functional in a monomeric state. A kinetic analysis of the purified enzyme was performed at 22 degrees C using a synthetic peptide substrate based on the primary sequence of the EGF receptor (KREL VEPLT669PSGEAPNQALLR). The Km(app) for ATP was 40 +/- 5 microM (mean +/- S.D., n = 3). GTP was not found to be a substrate for the purified enzyme. The Km(app) for the synthetic peptide substrate was 260 +/- 40 microM (mean +/- S.D., n = 3). The Vmax(app) for the isolated protein kinase was determined to be 400-900 nmol/mg/min. The purified enzyme was designated EGF receptor Thr669 (ERT) kinase. It is likely that the MAP2 and ERT kinases account for the phosphorylation of the EGF receptor at Thr669 observed in cultured cells. The marked stimulation of protein kinase activity caused by growth factors indicates that these enzymes may have an important function during signal transduction.
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PMID:Isolation and characterization of two growth factor-stimulated protein kinases that phosphorylate the epidermal growth factor receptor at threonine 669. 165 22

Variability in outcome of breast carcinoma among different racial groups has been identified between Japanese and Caucasians and between Caucasians and Blacks living in the United States. These differences are not fully explained by population differences of the known prognostic variables nodal involvement and tumor hormonal receptor status. Further elucidation of the differences in outcome should include a careful examination of other prognostic variables. These include tumor size, nuclear and histologic grade, and indicators of cell proliferation (labelling index and flow cytometric measures of S phase and DNA ploidy). More recent studies indicate that growth factor regulation, oncogene amplification (HER-2/neu) and expression, and cathepsin D levels may help to further identify prognostic subgroups. A review of the literature does not provide an answer to the question of whether there are population differences in response to standard treatments. Differences in drug distribution, elimination, and metabolism which could be related to genetic or dietary factors are intriguing hypotheses to explain why differences may exist. Careful, well controlled studies to answer these questions are urgently needed.
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PMID:Response to treatment of breast cancer. 165 92


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