Comparative antitumor activity of actinomycin analogs in mice bearing Ridgway osteogenic sarcoma or P388 leukemia
Abstract:
Actinomycin (Act) analogs, differing in the chemical substitution(s) made at various positions in either their pentapeptide chain(s) or chromophore ring, were evaluated for their antitumor activity in mice bearing either Ridgway osteogenic sarcoma (ROS) or P388 leukemia. Of the analogs tested against advanced (2--3-g) ROS tumors, azetomicin I and Act III caused therapeutic responses which, although variable, were nevertheless indicative of antitumor activities greater than was found using Act D. Several other analogs, Act C2, 2-N-(gamma-hydroxypropyl)-Act D, Act X0delta, and azetomicin II, displayed antitumor activity in ROS-bearing mice which varied, in different experiments, from comparable to superior to that achieved using Act D. Additionally, Act Pip1beta and 3'-(4-cisCl-Pro)-Act were comparable to, and Act-2-hydroxy-C3 inferior to, Act D in activity against ROS. Both azetomicin I and II were as effective as Act D in mice bearing P388 leukemia. Moreover, a subline of P388 that is resistant to Act D was cross-resistant to both azetomicin I and II.
Insights
New actinomycin analogs show promising antitumor activity against mouse cancers, with some analogs outperforming the standard drug Actinomycin D in certain models. Resistance studies also revealed cross-resistance patterns.
Area of Science:
- Pharmacology
- Medicinal Chemistry
- Oncology
Background:
- Actinomycin (Act) analogs are investigated for their potential antitumor properties.
- Chemical modifications to the pentapeptide chain or chromophore ring can alter analog activity.
- Actinomycin D (Act D) is a reference compound for evaluating new analogs.
Purpose of the Study:
- To evaluate the antitumor activity of various actinomycin analogs.
- To compare the efficacy of these analogs against Ridgway osteogenic sarcoma (ROS) and P388 leukemia models in mice.
- To assess cross-resistance patterns in Actinomycin D-resistant cell lines.
Main Methods:
- Synthesis of novel actinomycin analogs with diverse chemical substitutions.
- In vivo testing of analogs against established Ridgway osteogenic sarcoma and P388 leukemia in mice.
- Evaluation of therapeutic responses and comparison with Actinomycin D efficacy.
Main Results:
- Azetomicin I and Act III demonstrated antitumor activity superior to Act D against advanced ROS tumors.
- Several other analogs, including Act C2 and azetomicin II, showed comparable or superior activity to Act D in ROS models.
- Azetomicin I and II exhibited efficacy similar to Act D against P388 leukemia.
- A P388 subline resistant to Act D also showed cross-resistance to azetomicin I and II.
Conclusions:
- Certain novel actinomycin analogs possess significant antitumor activity, with some exceeding that of Actinomycin D in specific cancer models.
- The development of actinomycin analogs offers potential therapeutic advantages.
- Cross-resistance studies suggest shared mechanisms of action between some analogs and Actinomycin D.
