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Active Progesterone Receptor Antagonizes Estrogen Receptor in Endometrial Cancer

Semester: Summer 2023

Presentation description

While case numbers and deaths from most cancers are decreasing, numbers for endometrial cancer are increasing. Obesity, among other factors, remain as one of the most prominent risk factors for endometrial cancer. Also, therapy for this cancer has not evolved because, historically, Endometrial cancer has been treated by surgery. Historically, surgical options for patients with endometrial cancer have been successful, however, the development of targeted drug-based therapies has lacked in comparison to other cancers. Therefore, the central focus of my project is to determine how the progesterone (P4) pathway—which has demonstrated therapeutic benefit in some clinical settings—is altered in cancer cells.
P4 is a hormone receptor, and, given its putative role as a tumor suppressor our goal is to understand the underlying molecular characteristics of the progesterone receptor pathway.
The Ishikawa and HCI-ECI-23 endometrial cancer cell lines were used to do our experiments. Both Ishikawa and HCI-ECI-23 don’t express PR so we engineered a system to re-express PR-A and PR-B using Doxycycline (Dox). With these cell lines, we performed a Western Blot to look for the presence of PR-A and PR-B proteins. To show that PR is functional qPCR was conducted to determine that our recombinant PR induces the expression of endogenous gene targets. Additionally, ER activity was assesed using estrogen response element (ERE) luciferase assays. Global gene expression induced by treatment with estrogen (E2), P4, or combo E2 + P4 treatment was assessed by RNA-seq.
The Western blot showed that PR proteins were being produced at physiologic levels. We then saw that ER activity was reduced by active PR with the ERE luciferase assays. The engineered PR was functional as determined by qPCR of target genes and by analyzing RNA-seq data. Additionally, the presumed functional dominance of PR-B, we find that PR-A may also play a yet undiscovered role in the activation of endogenous targets. Interestingly, we found global antagonism of ER target genes in the combo E2 + P4 treatment where PR was active, suggesting a direct interaction of the two receptors. We speculate that PR may dominate over ER when both receptors are expressed and activated by hormone.

Presenter Name: Brianna Nevarez
Presentation Type: Poster
Presentation Format: In Person
Presentation #75
College: Medicine
School / Department: Oncological Sciences
Research Mentor: Craig Rush
Date | Time: Thursday, Aug 3rd | 10:30 AM