Induction of urothelial proliferation in rats by aristolochic acid through cell cycle progression via activation of cyclin D1/cdk4 and cyclin E/cdk2.
Aristolochic acid (AA) has been implicated in urothelial carcinoma in humans. However, the mechanism by which AA induces this cancer has not been completely established. To evaluate the effects of AA on the urinary bladder of rats, a histopathological study of three-month intragastric feeding with mixture of AA (41% AA I, 56% AA II) was carried out. A total of 18 experimental rats were divided into three feeding regimens, with six rats in each group (group I, normal basal diet; groups II and III received intragastric 5 mg and 10 mg isolated AA mixture/kg/day for 5 days/week for 12 weeks). Dosage-dependent urothelial proliferation, but not carcinoma, was found in the urothelium of the bladder of the rats administered with AA mixture. Immunoprecipitation showed elevations of cyclin D(1)/cdk4 (increased induction by 1.57- and 1.95-fold in the groups II and III) and/or cyclin E/cdk2 complex (increased induction by 1.46- and 1.62-fold in the groups II and III), which promote the increasing phosphorylation of Rb (increased induction by 1.75- and 2.07-fold in the groups II and III) and result in decrease of the Rb/E2F complex (decreased expression by 0.65- and 0.24-fold in the groups II and III). Our results provide evidence to suggest that exposure to AA results in urothelial proliferation in rats through cell cycle progression via activation of cyclin D(1)/cdk4 and cyclin E/cdk2.
Chang
Horng-Rong
HR
Division of Nephrology, Department of Internal Medicine, Chung-Shan Medical University Hospital, Taichung, Taiwan.
Lian
Jong-Da
JD
Lo
Chia-Wen
CW
Chang
Yun-Ching
YC
Yang
Mon-Yuan
MY
Wang
Chau-Jong
CJ
D000284:Administration, Oral; D000818:Animals; D034341:Aristolochic Acids / Q000633:toxicity*; D002273:Carcinogens / Q000633:toxicity*; D002453:Cell Cycle / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D019938:Cyclin D1 / Q000378:metabolism*; D019927:Cyclin E / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D047468:Immunoprecipitation; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D001743:Urinary Bladder / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D019459:Urothelium / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D034341:Aristolochic Acids; D002273:Carcinogens; D019927:Cyclin E; D019938:Cyclin D1; C000228:aristolochic acid I; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4