A Study of the Impact of Estrogen Signaling on Oncogenic Transformation in Patient-Derived Immortalized Breast Epithelial Cells

Presenter: Emaline McGibbon-Bloom

Faculty Sponsor: D Joseph Jerry

School: UMass Amherst

Research Area: Cancer Studies

Session: Poster Session 4, 2:15 PM - 3:00 PM, Auditorium, A75

ABSTRACT

Breast cancer impacts one in eight U.S. women, with risk factors both heritable and environmental. Studies have shown that women with increased estrogen exposure have a greater risk of developing breast cancer. This could, in part, be due to DNA damage induced by estrogen receptor alpha (ERα) signaling. However, all women are exposed to estrogen so it is unclear why breast cancer only develops in certain individuals.We hypothesize that estrogen signaling will increase oncogenic transformation in women with underlying defects in DNA repair. To study this we selected patient-derived immortalized breast epithelial cells (PD-iBECs) from women with no known susceptibility and women with inherited mutations in the BRCA1 DNA repair protein. We introduced the gene encoding ERα to control estrogen signaling. The PD-iBECs were further modified to disrupt the TP53 tumor suppressor gene and express an oncogenic HRAS, then grown in soft agar after being treated with or without estrogen to determine whether its presence increased oncogenic transformation. We confirmed control of ERα protein and expression of  ERα target genes. To select cells with knocked out TP53 we treated PD-iBECs with Nutlin, which causes apoptosis in cells with functional TP53. Loss of TP53 mRNA and protein was used to verify knockout. Hygromycin was used to select PD-iBECs with the HRAS transgene. Preliminary data showed that estrogen treated PD-iBECs from women with BRCA1 mutation showed increased oncogenic transformation. These results provide new tools for understanding why ERα signaling contributes to breast cancer development in a subset of women.

RELATED ABSTRACTS