Investigating the Mechanism of DNA-Protein Crosslink Formation Facilitated by Synthetic Aziridinomitosenes
Faculty Mentor Information
Dr. Don Warner (Mentor), Boise State University
Abstract
Aziridinomitosenes (AZMs) are DNA alkylating agents derived from the chemotherapeutic drug mitomycin C (MC). MC displays anti-tumor activity through the formation of DNA interstrand crosslinks (ICLs), which inhibit DNA replication, resulting in cell death. However, prior to DNA binding, MC must undergo a well studied bioreductive activation sequence. Historically, AZMs were known to produce DNA-monoalkylated adducts without reductive activation, while synthetic AZMs have been shown to generate both ICLs and DNA-protein crosslinks (DPCs) without reducing agents. Given that these were previously unreported adducts for AZMs, a nucleophilic activation sequence involving either of the C-6 or C-7 positions on the quinone ring (mitomycin numbering) was proposed. To test this mechanism, analogs with the C-6 and/or C-7 positions blocked were synthesized and tested via the ARK assay to quantify DPC formation. The C6-AZM and H-AZM formed significant DPCs (41.3 ± 1.9% and 10.2 ± 0.7%, respectively), while MC and dimethyl-AZM, both blocked at C-6 and C-7 positions, formed fewer DPCs (2.8 ± 0.4% and 5.6 ± 1.2%, respectively). These results indicate that AZMs unsubstituted at either C-6 or C-7 positions form significant amounts of DPCs, while those blocked at both positions do not.
Investigating the Mechanism of DNA-Protein Crosslink Formation Facilitated by Synthetic Aziridinomitosenes
Aziridinomitosenes (AZMs) are DNA alkylating agents derived from the chemotherapeutic drug mitomycin C (MC). MC displays anti-tumor activity through the formation of DNA interstrand crosslinks (ICLs), which inhibit DNA replication, resulting in cell death. However, prior to DNA binding, MC must undergo a well studied bioreductive activation sequence. Historically, AZMs were known to produce DNA-monoalkylated adducts without reductive activation, while synthetic AZMs have been shown to generate both ICLs and DNA-protein crosslinks (DPCs) without reducing agents. Given that these were previously unreported adducts for AZMs, a nucleophilic activation sequence involving either of the C-6 or C-7 positions on the quinone ring (mitomycin numbering) was proposed. To test this mechanism, analogs with the C-6 and/or C-7 positions blocked were synthesized and tested via the ARK assay to quantify DPC formation. The C6-AZM and H-AZM formed significant DPCs (41.3 ± 1.9% and 10.2 ± 0.7%, respectively), while MC and dimethyl-AZM, both blocked at C-6 and C-7 positions, formed fewer DPCs (2.8 ± 0.4% and 5.6 ± 1.2%, respectively). These results indicate that AZMs unsubstituted at either C-6 or C-7 positions form significant amounts of DPCs, while those blocked at both positions do not.