Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental evidence suggests that hematopoietic growth factors promote cell survival by suppressing apoptosis or programmed cell death. Since interleukin 3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF) induce tyrosine phosphorylation of a common set of proteins in the factor-dependent cell line M07e, we have investigated whether growth-factor-induced tyrosine phosphorylation is involved in the promotion of cell survival and suppression of apoptosis. Experiments were carried out with the leukemic cell lines HL-60 and M07e and the tyrosine kinase inhibitors genistein and tyrphostin AG82. Both the tyrosine kinase inhibitors induced apoptosis of HL-60 and M07e cells. This was indicated by the appearance of DNA degradation and morphologic evidence of nuclear condensation and fragmentation. It was also confirmed by flow cytometry of DNA, which showed apoptotic cells as a fraction of cells characterized by a diminished DNA stainability, represented on the DNA frequency histograms as a distinct peak below the G0/G1 population. Kinase inhibitors also reduced the fraction of cells in the S phase of the cell cycle. That tyrphostin specifically inhibited tyrosine kinases was further suggested by the prevention of its effects by the tyrosine phosphatase inhibitor sodium orthovanadate (vanadate), at least during the first 18-24 h of treatment. The incomplete prevention of genistein effects by vanadate suggests that genistein is a less specific inhibitor of tyrosine kinases than tyrphostin, and may also act as an inhibitor of topoisomerase II. Vanadate also prevented apoptosis and reduction of the S phase in M07e cells cultured for 24 h in the absence of growth factors. These results suggest that tyrosine phosphorylation is an essential step in IL-3 and GM-CSF signal transduction. Since in our experimental model the effects of tyrosine kinase inhibition and growth factor deprivation could be reversed by concomitant inhibition of tyrosine phosphatases, it is suggested that a balance between tyrosine kinases and tyrosine phosphatases establishes whether a cell will survive or undergo apoptosis.
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PMID:Inhibitors of tyrosine phosphorylation induce apoptosis in human leukemic cell lines. 825 1

The treatment of cancer may be associated with various chemotherapy-induced mucocutaneous reactions. One of the mucocutaneous adverse effects of antineoplastic drugs is the toxic local tissue reaction, the extravasation, which occurs in less than 1-2% of cytotoxic infusions. The standard management of vesicant extravasation includes: discontinuing all local infusions, aspiration of any residual drug, elevating the involved limb, local cooling or warm compresses, local anesthesia, antidotes (sodium thiosulfate for alkylating agents, dimethylsulfoxide (DMSO) for anthracyclines and mitomycin, and hyaluronidase for the vinca alkaloids), and finally surgical debridement with plastic surgery reconstruction. Because the anthracyclines are topoisomerase II poisons that are antagonized by topoisomerase II catalytic inhibitors such as dexrazoxane, it seems to be the treatment of choice immediately after extravasation of doxorubicin, epirubicin, daunorubicin, etc. One systemic dose of dexrazoxane after the accident may significantly reduce the toxic tissue lesions. Repeated intralesional injections of GM-CSF may accelerate the wound healing without the need of skin grafts.
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PMID:[The significance of extravasation in oncological care]. 1840 1