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Intercalator-induced, topoisomerase II-mediated DNA cleavage and its modification by antineoplastic antimetabolites
Abstract:
Defining specific biochemical targets of active antineoplastic agents could aid in discovering better anticancer therapy and more thoroughly understanding the biochemical basis of malignancy. Through a series of cellular and biochemical studies, we and others have identified the nuclear enzyme topoisomerase II as the target of several active agents, including 4'-(9-acridinylamino) methanesulfon-m-anisidide (m-AMSA). The interference with topoisomerase II produced by m-AMSA can be quantified in whole cells exposed to m-AMSA by using the alkaline elution technique to measure DNA cleavage. Antimetabolites such as ara-C, hydroxyurea, and 5-azacytidine can augment m-AMSA-induced, topoisomerase II-mediated DNA cleavage and, concurrently, m-AMSA-induced cell killing. Studies in proliferating and quiescent human cells and an m-AMSA-sensitive/resistant human leukemia cell pair further support the hypothesis that a connection exists between topoisomerase II-mediated DNA cleavage and the mechanism by which m-AMSA kills cells. Pharmacologic or hormonal modification of specific biochemical processes critical to drug-induced cytotoxicity may enhance the therapeutic index of clinically useful agents.
Insights
Researchers identified topoisomerase II as a key target for anticancer drugs like m-AMSA. Combining m-AMSA with antimetabolites enhances cancer cell killing by increasing DNA damage.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Identifying drug targets is crucial for developing effective anticancer therapies.
- The nuclear enzyme topoisomerase II is a target for antineoplastic agents such as m-AMSA.
- Understanding drug mechanisms aids in comprehending malignancy.
Purpose of the Study:
- To define the biochemical target of antineoplastic agents.
- To investigate the role of topoisomerase II in m-AMSA's mechanism of action.
- To explore strategies for enhancing anticancer drug efficacy.
Main Methods:
- Cellular and biochemical studies were conducted.
- Alkaline elution technique was used to quantify DNA cleavage in cells treated with m-AMSA.
- Studies involved proliferating and quiescent human cells and a leukemia cell pair.
Main Results:
- Topoisomerase II was confirmed as the target of m-AMSA.
- m-AMSA-induced DNA cleavage by topoisomerase II was quantified.
- Antimetabolites (ara-C, hydroxyurea, 5-azacytidine) augmented m-AMSA-induced DNA cleavage and cell killing.
- A link between topoisomerase II-mediated DNA cleavage and m-AMSA cytotoxicity was supported.
Conclusions:
- Topoisomerase II is a validated target for m-AMSA's anticancer activity.
- Enhancing topoisomerase II-mediated DNA cleavage can improve m-AMSA's efficacy.
- Modulating biochemical processes may enhance the therapeutic index of anticancer agents.