Modulation of carcinogenesis in the urinary bladder by retinoids

Area of Science:

• Oncology
• Chemoprevention
• Carcinogenesis research

Background:

• Bladder cancer exhibits high recurrence rates (70% within 5 years) and mortality.
• Two main patterns exist: exophytic papillary lesions and flat, invasive carcinoma.
• N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) is used to model these patterns in rats and mice.

Purpose of the Study:

• To evaluate the efficacy of retinoids in preventing bladder cancer in rodent models.
• To identify specific retinoids with significant anticarcinogenic activity and favorable toxicity profiles.

Main Methods:

• Utilized F344 rats and B6D2F1 mice treated with BBN to induce bladder tumors.
• Administered various retinoids to assess their impact on tumor development and urothelial differentiation.
• Compared the anticarcinogenic effects and toxicity of different retinoid analogues.

Main Results:

• Retinoids demonstrated the ability to delay or halt bladder cancer development in rats, improving urothelial differentiation.
• In mice, retinoids showed anticarcinogenic activity, though interpretation was complicated by non-uniform responses.
• N-(4-hydroxyphenyl)retinamide (HPR) emerged as the most effective anticarcinogenic retinoid in rodent bladders.
• HPR exhibited lower toxicity in rodents and better human tolerance compared to 13-cis-retinoic acid and etretinate.

Conclusions:

• Retinoids show promise as chemopreventive agents for bladder cancer.
• HPR is a highly effective and well-tolerated retinoid for bladder cancer chemoprevention in preclinical models.
• A human prophylactic trial of HPR for bladder cancer patients is planned.