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Oncogenic potential of bifunctional bioreductive drugs
1Center for Radiological Research, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA.
Abstract:
Potential oncogenicity must be a factor of concern in the design and development of novel bioreductive drugs. In the present studies, the cytotoxicity and oncogenic transforming potential of a series of heterocyclic mono-N-oxides, designed to be used as bioreductive drugs, were examined using the mouse C3H 10T1/2 cell system. Exponential phase cultures of 10T1/2 cells were treated with graded doses of the bioreductive drugs for a 4 h period, either in air or hypoxia, at 37 degrees C. After treatment, cultures were replated for both survival and transformation assays. The fused pyrazine mono-N-oxide RB 90740 and its N-deoxy analogue, RB 92816, demonstrated a dose-dependent cytotoxicity and oncogenic transforming potency under aerobic conditions. Similarly, the indoloquinone E09 and the structurally related mitomycin C demonstrated dose dependence in both toxicity and oncogenic transforming potential. The most cytotoxic aromatic-N-oxides tested, RB 92816, also demonstrated the highest oncogenic transformation incidence. In hypoxia, the bioreductive metabolites of RB 90740 were substantially more cytotoxic and induced a higher oncogenic transformation yield than the drug in air. These data are consistent with the structure-activity relationship for bioreductive drugs in that heterocyclic-N-oxides with reactive side chains such as RB 92816 are cytotoxic and potentially carcinogenic.
Insights
Novel bioreductive drugs, particularly heterocyclic mono-N-oxides, were evaluated for their oncogenic transforming potential. Some compounds, like RB 92816, showed dose-dependent cytotoxicity and oncogenic transformation, highlighting the need for careful drug design.
Area of Science:
- Pharmacology
- Toxicology
- Oncology
Background:
- Bioreductive drugs offer targeted cancer therapy.
- Assessing the oncogenic potential of novel bioreductive agents is crucial for drug development.
- Heterocyclic mono-N-oxides are a class of compounds being explored for bioreductive drug applications.
Purpose of the Study:
- To evaluate the cytotoxicity and oncogenic transforming potential of novel heterocyclic mono-N-oxides.
- To investigate the effects of aerobic and hypoxic conditions on drug activity.
- To establish structure-activity relationships for bioreductive drug safety.
Main Methods:
- Mouse C3H 10T1/2 cell system used for cytotoxicity and transformation assays.
- Cells treated with graded doses of bioreductive drugs under aerobic and hypoxic conditions.
- Survival and transformation assays performed after drug treatment.
Main Results:
- Fused pyrazine mono-N-oxide RB 90740 and RB 92816 showed dose-dependent cytotoxicity and oncogenic potential under aerobic conditions.
- Indoloquinone E09 and mitomycin C also exhibited dose-dependent toxicity and transforming potential.
- RB 92816, the most cytotoxic compound, displayed the highest oncogenic transformation incidence.
- Hypoxic conditions increased the cytotoxicity and oncogenic transformation yield of RB 90740 metabolites compared to aerobic conditions.
Conclusions:
- Heterocyclic mono-N-oxides with reactive side chains, such as RB 92816, are cytotoxic and potentially carcinogenic.
- Drug-induced oncogenic transformation is influenced by chemical structure and environmental conditions (air vs. hypoxia).
- These findings emphasize the importance of considering oncogenicity in the design of bioreductive drugs.