Limited tumor-initiating activity of phenylethyl isothiocyanate by promotion with sodium L-ascorbate in a rat two-stage urinary bladder carcinogenesis model.
Initiation activity of phenylethyl isothiocyanate (PEITC) was examined in a two-stage urinary bladder carcinogenesis model. Male 6-week-old Fischer 344 rats were fed diet containing 0.1% PEITC for 12 or 24 weeks, with or without subsequent administration of 5% sodium l-ascorbate (Na-AsA) in diet until week 48, or for the entire experimental period. After 12 weeks of PEITC-treatment, both simple hyperplasia and papillary or nodular (PN) hyperplasia had developed in all animals, but the majority of these lesions had disappeared at week 48, irrespective of the Na-AsA-treatment. The same lesions after 24 weeks of PEITC-treatment had progressed to dysplasia and carcinoma, in a small number of cases by week 48 (6% in incidence for each lesion), but enhancement by the Na-AsA-treatment was evident only with simple hyperplasias (from 56 to 100% in incidence) and PN hyperplasias (from 19 to 56%). The results suggest a limited initiation activity of PEITC with induction of irreversible lesions by 24 weeks of exposure.
Takagi
Hironori
H
Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
Shibutani
Makoto
M
Uneyama
Chikako
C
Lee
Kyoung-Youl
KY
Kato
Natsumi
N
Inoue
Kaoru
K
Hirose
Masao
M
D000818:Animals; D001205:Ascorbic Acid; D001835:Body Weight / Q000187:drug effects; D002277:Carcinoma / Q000139:chemically induced*; D004032:Diet; D006965:Hyperplasia / Q000139:chemically induced; D017879:Isothiocyanates / Q000633:toxicity*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced*
D017879:Isothiocyanates; C058305:phenethyl isothiocyanate; D001205:Ascorbic Acid