Transplacental carcinogenesis by cisplatin in F344/NCr rats: promotion of kidney tumors by postnatal administration of sodium barbital.

Transplacental carcinogenic effects of cis-dichlorodiammineplatinum (cis-DDP) in F344 rats were investigated. Pregnant F344 rats were given a single i.p. administration of either cis-DDP (5 mg/kg body wt; group 1) or saline only (group 2) on Day 18 of gestation. Offspring of groups 1 and 2 were randomly and equally divided into two subgroups: 1a, 1b and 2a, 2b, respectively. Beginning at 4 weeks of age, offspring in groups 1b and 2b received 500 ppm of sodium barbital (NaBB) in diet, while those in groups 1a and 2a received normal diet. The experiment was terminated at 79 weeks of age. A low incidence (2/19; 10.5%) of male offspring exposed to transplacental cis-DDP (group 1a) developed renal cell adenomas. Postnatal administration of NaBB significantly enhanced this incidence (10/22; p < 0.01) in cis-DDP-initiated offspring. Also, multiple kidney tumors were more common in group 1b than any other group and three animals in this group developed frank renal cell carcinomas. cis-DDP, administered transplacentally, was a complete carcinogen for rat liver as the incidence of hepatocellular adenomas was significantly higher in offspring exposed transplacentally to cis-DDP than in those exposed to saline (20/82 vs 3/75; p < 0.05). NaBB, a known promoter of hepatocellular carcinogenesis in adult rats initiated with N-nitrosodiethylamine, failed to promote liver carcinogenesis initiated by transplacental cis-DDP. Tumors of the central nervous system (3/82; gliomas) and peripheral nervous system (2/82; schwannomas) were found only in offspring exposed transplacentally to cis-DDP. Thus, cis-DDP, administered transplacentally, was a strong initiator of renal cell tumors and a complete carcinogen for multiple organs in rat offspring.