Abstract A96: Correlation of estrogen receptor beta with immune cells in colon cancer patients

Abstract Background: The estrogen receptor β (ERβ) is the predominant ER in the colon mucosa. We have previously reported that high expression of ERβ is independently associated with a better prognosis in patients with colorectal cancer (CRC), and the induction of this receptor in colon cancer cell lines resulted in upregulation of antitumorigenic proteins and downregulation of protumorigenic proteins. In addition, we have also shown that high mast cell density (MCD) was associated with longer survival of CRC patients. Aim: To investigate the correlations between ERβ, mast cells (MCs), and prostaglandin D2 (PGD2) synthase. Materials and Methods: A tissue microarray (TMA) of primary CRCs from 314 patients was stained for the expression of ERβ, MCs, and PGD2 synthase. Immunohistochemistry was used to evaluate the staining intensity by using the immunoreactive score (IRS). Results: Patients with high ERβ expression had higher number of MCs, and there was a significant positive correlation between ERβ and MCs (r = 0.12, P = 0.03). In addition, patients with high ERβ expression had significantly higher activity of PGD synthase, which is produced mainly from MCs and is known to have antitumor effects. Furthermore, a strong, positive, and significant correlation was observed between ERβ expression and PGD synthase (r = 0.42, P < 0.0001). Future Plans: We aim to correlate the expression of ERβ with other immune cells and factors important for the tumor microenvironment, such are CD3+, CD8+, T-bet, and PDL-1. Conclusion: High ERβ expression correlates with an antitumor immune prolife in CRC patients. This strengthens our hypothesis that the induction of ERβ expression in CRC patients will potentially improve the disease outcome. Citation Format: Geriolda Topi, Marie Louise Lydrup, Anita Sjölander. Correlation of estrogen receptor beta with immune cells in colon cancer patients [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A96.