Altered MicroRNA Expression Patterns During the Initiation and Promotion Stages of Neonatal Diethylstilbestrol-Induced Dysplasia/Neoplasia in the Hamster Uterus.

Abstract

Treatment of hamsters on the day of birth with the synthetic estrogen and prototypical endocrine disruptor, diethylstilbestrol (DES), results in a 100% incidence of uterine hyperplasia/dysplasia in adulthood and a large proportion of the disrupted organs progress to neoplasia (endometrial adenocarcinoma). Further investigation of this pathological phenomenon at the histomorphological level determined that, in accordance with the classic two-stage model of carcinogenesis, the neonatal DES exposure event directly and permanently disrupts the developing hamster uterus (initiation stage) so that it responds abnormally when it is stimulated with the natural ovarian estrogen, estradiol (E2), in adulthood (promotion stage). Our previous investigations of molecular elements involved in progression of the disruption/neoplastic process involved analyses of altered gene expression at the mRNA and protein levels. To widen that investigation, we performed microRNA (miRNA)-targeted microarray analyses on triplicate sets of uterine RNA extracts from 5-day old animals (initiation stage) and from 2-month old animals that were chronically stimulated with E2 (promotion phase). At the miRNA level, the number of genes whose mean expression levels were significantly (ANOVA, p-value < 0.05) different in DES-exposed vs. control uteri were:-Initiation Stage/Up-Regulated: 43 (8 >2-fold; miR-200b, 200a, 429, 29a, 141, 200c, 29b, 21)-Initiation Stage/Down-Regulated: 32 (1 >2-fold; miR-181a)-Promotion Stage/Up-Regulated: 29 (none >2-fold)-Promotion Stage/Down-Regulated: 33 (1 >2-fold; miR-133a)These results corroborate previous demonstrations at the mRNA and protein levels that progression of the neonatal DES-induced disruption/neoplasia process in the hamster uterus involves a spectrum of gene expression alterations. However, the collection of both structural and miRNA-coding genes and their manner of altered expression was quite different during the initiation vs. promotion stages of the phenomenon. (platform)