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Chemoprevention of experimental carcinogenesis in animals
1Laboratory of Pathophysiology, IIT Research Institute, Chicago, Illinois 60616.
Abstract:
Retinoids are well-established chemopreventive agents for experimental carcinogenesis of many target organs including mammary glands, urinary bladder, lung, skin, liver, pancreas, colon, and esophagus. Modification of the basic retinoid structure has produced analogs with enhanced target organ specificity, increased inhibitory activity, and reduced toxicity. N-(4-hydroxyphenyl)retinamide (4-HPR) currently appears to be the most efficacious retinoid against carcinogen-induced breast, urinary bladder, and lung cancer in rodents. Retinoids are most effective when administered shortly after the carcinogen treatment; however, the treatment can be delayed significantly while maintaining its chemopreventive effect. Under various experimental conditions combining retinoid treatment with other modifiers of growth enhances its chemopreventive activity; for example retinoid plus hormonal modulation can provide better protection against mammary cancer than either treatment alone. More recently chemopreventive activity of various other classes of agents, such as thiols, phenols, antioxidants, inhibitors of prostaglandin synthesis, etc., have been investigated in experimental mammary, urinary bladder, and lung cancer models.
Insights
Retinoids are effective cancer chemopreventive agents for multiple organs. N-(4-hydroxyphenyl)retinamide (4-HPR) shows high efficacy, and combining retinoids with other agents enhances protection against experimental cancers.
Area of Science:
- Oncology
- Chemoprevention Research
- Experimental Carcinogenesis
Background:
- Retinoids are established chemopreventive agents against experimental carcinogenesis in various organs.
- Structural modifications of retinoids yield analogs with improved specificity, efficacy, and safety.
- N-(4-hydroxyphenyl)retinamide (4-HPR) is a highly effective retinoid for preventing rodent breast, bladder, and lung cancers.
Purpose of the Study:
- To review the chemopreventive efficacy of retinoids and their analogs.
- To explore the optimal timing and combination strategies for retinoid chemoprevention.
- To highlight emerging classes of chemopreventive agents.
Main Methods:
- Review of experimental studies on retinoid chemoprevention.
- Analysis of structure-activity relationships for retinoid analogs.
- Investigation of combination therapies with retinoids and other agents.
Main Results:
- Retinoids demonstrate broad efficacy across multiple organ systems in preventing experimental cancers.
- N-(4-hydroxyphenyl)retinamide (4-HPR) exhibits significant potency against induced breast, bladder, and lung cancers.
- Chemopreventive effects are maintained even with delayed retinoid administration.
- Combined retinoid and hormonal therapy enhances protection against mammary cancer.
- Other agents like thiols, phenols, and antioxidants are also being investigated.
Conclusions:
- Retinoids, particularly 4-HPR, are potent chemopreventive agents with potential for broad application.
- Combination strategies and optimized timing can enhance retinoid efficacy.
- Ongoing research explores diverse agents for cancer chemoprevention.