This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Mechanism of action of actinomycin D is ? \nSelect and explain. \nA. Inhibits DNA dependent RNA synthesis, B. Activates DNA dependent RNA synthesis, C. Inhibits RNA dependent DNA synthesis, D. Activates RNA dependent DNA synthesis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Inhibits DNA dependent RNA synthesis The anticancer antibiotics are Actinomycin - D (Dactinomycin) Daunorubicin (Rubidomycin) Mitomycin C Doxorubicin Mitoxantrone Mithramycin (plicamycin) Bleomycins These anticancer, antibiotics obtained from micro-organisms and have prominent antitumour activity. Mechanism of action : They are intercalated between DNA strands and interfere with its template function. Actinomycin `D' inhibits DNA dependent RNA synthesis. Bleomycin cause DNA breakage and free radical formation . Doxo-and daunorubicin inhibit Topoisomerase I & II. Mitomycin acts like alkylating agents. Mitoxantrane binds to DNA to produce strand breakage and inhibits both DNA & RNA synthesis. Remember All antitumor antibiotics are cell cycle nonspecific except for bleomycin which acts in G2 phase.", 'role': 'assistant'}]