Effect of delay in administration of 13-cis-retinoic acid on the inhibition of urinary bladder carcinogenesis in the rat
Becci, P.J.; Thompson, H.J.; Grubbs, C.J.; Brown, C.C.; Moon, R.C.
Cancer Research 39(8): 3141-3144
1979
ISSN/ISBN: 0008-5472 PMID: 455298 Document Number: 151543
The effect of a delay in starting 13-cis-retinoic acid treatment on the inhibition of urinary bladder carcinoma induced by N-butyl-N-(4-hydroxybutyl)nitrosamine was studied in male Fischer 344 rats. Animals received a total p.o. dose of either 1200, 1800 or 2400 mg N-butyl-N-(4-hydroxybutyl)nitrosamine over a period of six weeks. At either one, five, and nine weeks after the last N-butyl-N-(4-hydroxybutyl)nitrosamine intubation, animals were started on a diet supplemented with 13-cis-retinoic acid (240 mg/kg of laboratory chow) or continued on laboratory chow. Animals were killed at one year after the first carcinogen intubation for histological evaluation of the bladder. Feeding of 13-cis-retinoic acid reduced the incidence, average number, and severity of transitional cell carcinomas as well as hyperplasia and cellular atypia. Furthermore, even a nine-week delay in starting the retinoid feeding did not diminish the ability of 13-cis-retinoic acid to inhibit bladder carcinogenesis.