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[Recent advanced studies on mitomycins, antitumor activity and mode of action]
Abstract:
Mitomycin C (MMC) showed a wide antitumor spectrum with regression of various tumors and the optimal schedule of a single or intermittent administration against human tumor cells xenografted to nude mice, confirming the early reports obtained in rodent tumor system. The sensitivity of various human tumors xenografted to nude mice has been tested to antitumor agents to establish the system which could select the clinically active drugs. The effectiveness of MMC against human stomach cancers xenografted to nude mice clearly correlated to the clinical effect of MMC against gastric cancer. The covalent cross-link adducts between MMC and DNA were isolated in the bioreductive system of NADPH-cytochrome C reductase and NADPH, and the major monoadduct was determined as N2-(2'' beta 7'-diaminomitosen-1''-alpha yl)-2'-deoxyguanine. Importantly, bisadduct was isolated, and the structure was determined by spectroscopic method. DNA-DNA cross-link formation was shown by alkaline elution in cells treated with MMC. The activation of MMC has been characterized by the two electron transfer process, however, the one electron transfer process was proposed by electrochemical analysis. MMC was effective against hypoxic cells. Several cell lines resistant to MMC were isolated, and some MMC derivatives showed in vivo and in vitro anti-tumor activity against these resistant cells.
Insights
Mitomycin C effectively treats various tumors in mice, showing promise for human cancer treatment. Its DNA cross-linking mechanism and effectiveness against hypoxic cells warrant further investigation for drug development.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Context:
- Established nude mouse models for evaluating antitumor agents against human tumor xenografts.
- Confirmed previous findings on Mitomycin C's efficacy in rodent tumor systems.
Purpose:
- To assess the antitumor spectrum and optimal administration schedule of Mitomycin C (MMC).
- To establish a system for selecting clinically active drugs using human tumor xenografts.
- To elucidate the DNA-damaging mechanisms of MMC and its activity against resistant cells.
Summary:
- Mitomycin C demonstrated broad-spectrum antitumor activity and tumor regression in human tumor xenografts in nude mice.
- The study identified specific DNA adducts formed by MMC and confirmed DNA-DNA cross-linking.
- Mitomycin C showed effectiveness against hypoxic cells, and derivatives were active against resistant cell lines.
Impact:
- The findings support Mitomycin C's clinical relevance, particularly for gastric cancer.
- Understanding MMC's mechanism provides insights for developing novel anticancer drugs.
- The study highlights the potential of MMC derivatives in overcoming drug resistance.