Histological Analysis of Disrupted Proteomics 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). Extensive histomorphological investigation of this pathological phenomenon established 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, IS) so that it responds abnormally when it is stimulated with the natural ovarian estrogen, estradiol (E2), in adulthood (promotion stage, PS). Molecular elements involved in both stages of this phenomenon were first profiled by microarray and immunoblot analyses of total RNAs and proteins extracted from whole uteri. Those analyses at the whole-organ level revealed a number of genes whose expression at both the mRNA and protein level were at least 2-fold and significantly different in neonatally DES-exposed vs. control uteri. Our follow-up immunohistochemical analyses based on those profiling findings generated the following observations: Progesterone Receptor: Nuclear staining in both epithelial and stromal cells up-regulated in IS but down-regulated in PS. E-Cadherin: Epithelial cell membrane staining up-regulated in both IS and PS. Insulin Receptor Substrate-1 (IRS-1): Nuclear staining in stromal cells up-regulated in IS. Specificity Protein 1 (Sp1): Epithelial and stromal cell nuclear staining down-regulated in PS. Signal Transducer and Activator of Transcription 5A (Stat5A): Cytoplasmic staining in epithelial cells up-regulated in IS. Tenascin: Stromal extracellular matrix staining up-regulated in IS (altered distribution in PS). These results provide important new tissue/cell-specific information about altered proteomics in our experimental system. They also confirm that: 1) progression of the neonatal DES-induced disruption/neoplasia process in the hamster uterus involves a spectrum of gene expression alterations, and 2) the complex of genes and their manner of altered expression is quite different during the initiation vs. promotion stages of the phenomenon. Supported by the Flossie E. West Memorial Foundation and NIH grant P20 RR016475. (poster)