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theses

Previous work from our laboratory found that alcohol exposure in utero using the Lieber-DeCarli diet increases the risk of carcinogen-induced mammary tumorigenesis in adult rat offspring; however, the underlying mechanism remains unknown. The mature mammary gland is established after birth and maintained throughout adulthood by a mammary cell lineage where stem cells produce progenitor cells that generate differentiated epithelial cells comprising the ductal and secretory structures of the adult gland. Altering the mammary cell composition has been shown to increase susceptibility to tumorigenesis. Therefore, we hypothesized that alcohol exposure in utero may target cells along the mammary epithelial cell (MEC) lineage, shifting it towards one that promotes tumorigenesis. To test this hypothesis, we investigated the effects of fetal alcohol exposure (FAE) in normal and hyperplastic mammary glands, utilizing the MMTV-Wnt1 mouse model of breast cancer. FVB/NJ female mice were bred to MMTV-Wnt1 male mice to produce both wild-type (WT) and transgenic (Tg) female offspring. Alcohol dams were given ad-lib access to 5% alcohol in 0.2% saccharin solution from GD9-10 and 10% alcohol in 0.2% saccharin from GD11-GD19. Control dams were given ad lib access to 0.2% saccharin solution from GD9-GD19. Thoracic and inguinal mammary glands from WT and Tg offspring were harvested at puberty (5 weeks of age) and adulthood (10 weeks of age) and dissociated to yield a single cell suspension enriched for MECs. To determine the effects of FAE on the mammary gland, MECs were analyzed by flow cytometry to characterize the luminal, luminal progenitor and basal epithelial subpopulations. WT glands of FAE animals exhibited a decreased basal cell population and increased luminal:basal ratio at 10 weeks of age. qRT-PCR analysis of total MECs found that Hey1 mRNA expression was increased in the WT FAE group at 10 weeks of age. In Tg glands FAE increased the luminal progenitor cell population at 5 weeks of age but did not alter MEC composition at 10 weeks of age. Total MECs were plated for mammosphere assay and passaged twice to monitor secondary and tertiary mammosphere formation. Tertiary mammosphere forming efficiency was greater in the WT glands of FAE animals at 10 weeks of age; however, this effect was not observed in the WT glands at 5 weeks of age or in Tg glands at either age. To further investigate how an altered MEC composition may affect tumorigenesis, a subset of Tg female offspring was followed for tumor formation. Overall, tumor latency was decreased in the FAE group. Flow cytometry analysis indicated that FAE females developed tumors with an increased basal cell population. These data indicate that FAE can shift MEC subpopulations, increasing the proportion of cells that are potentially vulnerable to transformation and affecting cancer risk.

ETD_10183

Ph.D.

Includes bibliographical references

doi:10.7282/t3-jnf8-hb05

ETD doctoral

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