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Type Itopoisomerases relax the DNA, transform a superhelical DNA into a relaxed DNA by reversibly cleaving one strand of duplex DNA. This creates the prerequisite for the reading, i.e. transcription of the DNA. After successful DNA replication, the DNA gap is closed again. Type I topisomerase always reversibly cleaves only one strand of DNA. Topoisomerase inhibitors I allow DNA cleavage, stabilise the topoisomerase-DNA complex and prevent the enzyme from closing the cleavage site again. This leads to the breakage of the DNA strand and the cell is driven into apoptosis. Topoisomerase inhibitor I develops the strongest antineoplastic activity in the S phase.
The type II topoisomerases act ATP-dependent. They are able to separate both DNA strands. In the case of teniposide, a semi-synthetic glycosidic podophyllotoxin derivative (see also etoposide), the glycoside binds with the DNA and the topoisomerase to form a stable complex that allows the cleavage of the DNA double strand but prevents the re-closure of the resulting DNA gap. The enzyme remains bound to the free end of the DNA. The transcription comes to a standstill. The cell gives the signal for its own cell death(apoptosis) because the arrest of DNA relaxation can no longer be released.
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IndicationThis section has been translated automatically.
Acute lymphatic leukemia of the child (ALL), Hodgkin lymphoma, brain tumors (glioblastoma, ependymoma, astrocytoma, neuroblastoma); malignant tumors of the urinary bladder
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Hypersensitivity to the active substance, podophyllotoxin and podophyllotoxin derivatives Use of a yellow fever vaccine or other live vaccines
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LiteratureThis section has been translated automatically.
- Chu B et al (2016) Preparation and evaluation of teniposide-loaded polymeric micelles for breast cancer therapy. Int J Pharm 513(1-2):118-129.
- Dorr RT et al (1983) Skin ulceration potential without therapeutic anticancer activity for epipodophyllotoxin commercial diluents. Invest New Drugs 1: 151-159
- McVie JG (1992) Teniposide (VM-26) in brain tumors. Semin Oncol 19(2 Suppl 6):85-88.