Abstract 266: Angiotensin I-7 modulates transcriptional (de)activation of multiple members of steroid hormone receptor superfamily: Possible mechanisms underlying inhibited proliferation in (T47D) human breast cancer cells

Abstract

Abstract Introduction: Renin Angiotensin System (RAS) is correlated to breast cancer and to other types of cancer. Angiotensin I-7 [Ang-(I-7)] is an endogenous 7-amino acid peptide hormone of this system that has anti-proliferative properties. Interestingly, there are increasing evidences that RAS is implicated in the development of breast cancer. Objectives: We aimed to evaluate the expression of steroid hormone receptors (progesterone receptors (PR), estrogen receptors (ER), androgen receptors (AR), apoptosis and proliferation in tumoral (T47D) epithelial mammary cell line, after Ang-(I-7) treatment. Methods: Tumoral (T47D) cultured cell line was treated with angiotensin I-7 peptide and cells were harvested after 2, and 15 days, when expression analysis of steroid hormone receptors was performed by real time PCR. The same treatment was used for the apoptosis and cell cycle analyses, done using the 5HT-GUAVA flow cytometer. Results: Expression of steroid hormone receptors implicated to breast carcinogenesis such as genomic progesterone receptors (PR(A+B) and PRB), estrogen receptors (Era and ERb), androgen receptor (AR) were never investigated together in the sex hormone-sensitive human breast cancer cell T47D after angiotensin I-7 exposure. When T47D cells were treated with angiontensin I-7 peptide were all up-regulated of the control level (PRA+B (1.0-fold), PRB (2.3-fold), Era (7.8-fold), ERb (8.1-fold) and AR (1.9-fold) - p < 0.01) in early treatment (2 days). However, important down-regulation of all receptors was observed after 15 days. T47D responded by down-regulating PRA+B (-3.5-fold), PRB (-3.1-fold), Era (-4.3-fold), ERb (-4.6-fold) and AR (-6.05-fold), all compared to basal conditions (p < 0.001). The functional relevance of steroid hormone receptors inhibition in sensitive human breast cancer cell line was confirmed by flow cytometry, assaying cell viability, apoptosis and proliferation by flow cytometry. Ang-(I-7) 2 day treatment significantly increased cell cycle in all phases (G0/G1, S and G2/M) when compared to control and decreased apoptosis (p < 0.05), but after 15 days there was a significant reduction in all cell cycle phases (p < 0.05) and increased apoptosis indexes were observed (p < 0.001). Conclusion: These results suggest anti-proliferative actions of Ang-(I-7), which has already been demonstrated previously for this peptide by our research group (Alecrim et al, 2011). Moreover, we could also observe a pro-apoptotic effect sustained for 15 days in these cells, and it seems to be correlated to the down-regulated expression of all steroid hormone receptors studied. In summary, Ang-(1-7) drives T47D cells to apoptosis and the use of the peptide as a novel therapeutic compound for breast cancer should be considered. Support: FAPESP Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 266. doi:1538-7445.AM2012-266