The role of altered microRNA expression in an experimental model of estrogen-dependent uterine cancer
This project screened for altered expression of small RNA species, microRNAs (miRNA), in the hamster uterus following neonatal exposure to the potent synthetic estrogen and established endocrine disruptor diethylstilbestrol (DES). Neonatal DES exposure results in a dysplastic/neoplastic response of the adult hamster uterus to the natural ovarian estrogen, estradiol (E2). In the present study, miRNA profiling was performed with total RNA extracted from the uteri of control and neonatally DES-treated female hamsters. We exploited a highly sensitive, reliable, and accurate microarray profiling technology and used it to screen for the differential expression of miRNA genes during both the initiation and promotion stages of estrogen-dependent endometrial adenocarcinoma in the neonatally DES-treated hamster. MiRNAs that were two-fold or more differentially expressed in DES-treated animals compared with the control animals were validated using a sensitive and highly specific quantitative RT-PCR technique. In the initiation stage a total of eight miRNAs including the miR-200 family members miR-200a, miR-200b, miR-200c, miR-141 and miR-429; miR-29a/b and miR-21 that is found altered in many cancers were up-regulated more than 2-fold; and one miRNA, miR-181a, was down-regulated by more than 2-fold. However, there was only a single down-regulated miRNA, miR-133a, at the 2-month old promotion stage. These results were validated by the qRT-PCR assays. The change in miRNA expression was expressed as ∆CT values+/- standard error of means (SEM) with statistical significance assessed by student's t-test (p<0.05). The results suggest that the molecular mechanism of neonatal DES-induced uterine dysplasia/neoplasia in the hamster involves altered expression of specific miRNAs; perhaps more importantly during the initiation than the promotion stage of the phenomenon.
Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Biological Sciences