Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The kinetics of inhibition of the epidermal growth factor (EGF) receptor (EGFR) tyrosine kinase (TK) activity by erbstatin, tyrphostins, and lavendustin derivatives were studied in a system that employs poly(Glu6Ala3Tyr) (GAT) and ATP as substrates, after preactivation with EGF. All data were analyzed for computer best-fit curves by a program that was written for this purpose and is available upon request to those interested. The inhibition kinetics followed a sequential, Bi-Bi, rapid equilibrium, random mechanism, the mechanism of the EGFR-TK. Erbstatin and a few tyrphostins that contain a 3,4-dihydroxy-(cis)-cinnamonitrile [1-(3',4'-dihydroxyphenyl)-2-nitriloethene] group were found to be pure competitive inhibitors with respect to both substrates of the kinase reaction, i.e., GAT and ATP. Two tyrphostins, each containing an additional dihydroxyphenyl group in the alpha-position, were found to be pure competitive inhibitors with respect to GAT and noncompetitive (or mixed-competitive) inhibitors with respect to ATP. A lavendustin derivative with a 2,5-dihydroxyphenyl ring and a lavendustin derivative with a 3,4-dihydroyphenyl ring were also found to be competitive inhibitors with respect to both ATP and GAT. Various possible modes of binding at the EGFR-TK active center for the tyrphostins studied are proposed and the significance of the present findings, as well as the interpretations of computer analyses of kinetic data, is discussed.
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PMID:Kinetics of inhibition by tyrphostins of the tyrosine kinase activity of the epidermal growth factor receptor and analysis by a new computer program. 818 46

Thirty-five patients with ovarian tumors operated on between December, 1989 and June, 1991 were studied to detect K-ras codon 12 point mutation (PM). (1) Five of 35 ovarian tumors (14.3%) disclosed K-ras PM at codon 12 and all the PM cases were in transition from GGT to GAT. On the other hand only one case (5.3%) with K-ras oncogene amplification was found and no C-myc or erbB-2 amplification was detected. (2) The incidence of PM according to clinical stages was seen in 3 of 11 stage I cases (27.3%), in 1 of 3 stage II cases (33.3%), in 1 of 14 stage III cases (7.1%) and in neither of 2 stage IV cases. PM was therefore seen in relatively early stages. (3) The occurrence of PM according to the histologic type was found in 3 of 16 serous tumors (18.8%), in 2 of 5 mucinous tumors (40.0%) and in none of 7 clear cell carcinomas or 2 endometrioid carcinomas. (4) Concerning the relation of PM to the involvement of serosal surface of ovarian tumors and to the ascitic cytology, no particular correlation was observed in our study. (5) Regarding the cytologic findings in imprint smears of the tumors in reference to PM, such as nuclear size, shape, N/C ratio, chromatin pattern, nucleolar size and number, the cases with PM tended to have more multiple nucleoli than PM negative cases. No other findings seemed to indicate the clinical progress of cancer. In conclusion, our study indicated that PM in ovarian cancers was a relatively early event in carcinogenesis.
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PMID:[Studies on the point mutation of ras oncogene in ovarian tumor]. 825 28

The naphthodianthrone hypericin produces a potent and irreversible inhibition of the epidermal growth factor (EGF) receptor tyrosine kinase activity. The inhibition was time and temperature dependent but did not depend on EGF activation. The IC50 values obtained were 0.37-8.7 microM with membranes incubated for 30 min at 30 degrees or 10 min at 0 degree, respectively. Kinetic analyses with poly(Glu,Ala,Tyr) 6:3:1 [poly(GAT)] as an exogenous substrate were in agreement with the irreversible nature of the inhibition. Irradiation for 30 min with fluorescent light caused a dramatic photosensitizing effect and resulted in an IC50 value of 44 nM. This effect was due to a type I mechanism, since the exclusion of oxygen did not alter the inhibition curve. The inhibition was inversely proportional to the amounts of membranes used, which probably reflects the non-specific sequestration of hypericin into the lipid bilayer. Ser/Thr protein kinases such as protein kinase A, casein kinase 1 and 2 and the enzyme 5'-nucleotidase, were not inhibited by hypericin not even at high concentrations (> 100 microM).
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PMID:Inhibition of epidermal growth factor receptor tyrosine kinase activity by hypericin. 826 42