Actinomycin

Actinomycin is any of a class of polypeptide antibiotics isolated from soil bacteria of the genus Streptomyces.

Mechanism
Actinomycin-D is primarily used as an investigative tool in cell biology to inhibit transcription. It does this by binding DNA at the transcription initiation complex and preventing elongation by RNA polymerase.

As it can bind DNA duplexes, it can also interfere with DNA replication, although other chemicals such as hydroxyurea are better suited for use in the laboratory as inhibitors of DNA synthesis.

As chemotherapy
Actinomycin-D is marketed under the trade name Dactinomycin. Actinomycin-D is one of the older chemotherapy drugs which has been used in therapy for many years.

It is a clear, yellow liquid which is administered intravenously and most commonly used in treatment of a variety of cancers, including:


 * gestational trophoblastic neoplasia
 * Wilms' tumor
 * rhabdomyosarcoma

As an antibiotic
It was the first antibiotic shown to have anti-cancer activity, but is not normally used as such, as it is highly toxic, causing damage to genetic material.

It was the first antibiotic ever isolated by Selman Waksman.

Research use
Actinomycin-D and its fluorescent derivative, 7-amino-actinomycin D, are used as stains in microscopy and flow cytometry applications. The affinity of these stains compounds for GC-rich regions of DNA strands makes them excellent markers for DNA.

7-amino-actinomycin D (7aad) is used as a DNA stain .7aad binds to single stranded DNA. Therefore it is a useful tool in determining apoptosis and distinguishing between dead cells and live ones. (Source)