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Inhibition of carcinogenesis by retinoids
Abstract:
Experimental investigations of the antineoplastic effects of retinoids are reviewed in this paper. In vitro studies have shown that the hyperplastic and metaplastic response to chemical carcinogens of mouse prostate cultures is suppressed by the addition of retinoids to the culture medium, that retinoids can partially inhibit the morphologic transformation of 10T 1/2 cells by physical or chemical carcinogens, and that the growth of some non-neoplastic and some neoplastic cell lines can be inhibited by retinoids. In vivo studies have shown that retinoids can suppress papilloma and carcinoma development (the promotion phase) in the two-stage skin carcinogenesis assay, inhibit mammary and bladder carcinogenesis in mice and rats, and inhibit the growth of some transplantabletumor lines. So far it has not been possible to inhibit predictably tumour formation in the intestinal tract or the respiratory tract of rodents. Almost all the synthetic retinoids have a higher therapeutic index than the natural retinoids in the prevention or treatment of cancer.
Insights
Retinoids show promise in cancer prevention and treatment by suppressing tumor development in various models. Synthetic retinoids offer a better therapeutic index than natural ones for antineoplastic effects.
Area of Science:
- Oncology
- Molecular Biology
- Carcinogenesis
Background:
- Retinoids, vitamin A derivatives, are investigated for their potential antineoplastic effects.
- Understanding retinoid mechanisms is crucial for developing novel cancer therapies.
Purpose of the Study:
- To review experimental evidence on the antineoplastic effects of retinoids.
- To assess the efficacy of retinoids in preventing and treating various cancers.
Main Methods:
- In vitro studies using cell cultures and carcinogen exposure.
- In vivo studies involving animal models of carcinogenesis (skin, mammary, bladder).
- Evaluation of retinoid effects on tumor promotion and growth.
Main Results:
- Retinoids suppressed hyperplastic/metaplastic responses in mouse prostate cultures.
- Retinoids partially inhibited morphologic transformation of cells by carcinogens.
- Retinoids inhibited papilloma/carcinoma development in skin, and carcinogenesis in mammary/bladder tissues.
- Retinoids inhibited the growth of some transplantable tumor lines.
- Inhibition of tumor formation in intestinal/respiratory tracts was not predictable.
- Synthetic retinoids demonstrated a higher therapeutic index than natural retinoids.
Conclusions:
- Retinoids exhibit significant antineoplastic effects in preclinical models.
- Synthetic retinoids are more favorable for cancer prevention and treatment due to their therapeutic index.