Abstract P2-19-02: Androgen mediated signaling induces epithelial to mesenchymal transition phenotype in MDA-MB-453 breast cancer cells and human breast tumors

Abstract Background: Epithelial-mesenchymal transition (EMT) phenotype is a complex process and plays a central role in tumor progression, aggression, invasion, metastasis, and resistance to therapy. Role of androgen receptor (AR) and androgens in inducing EMT has been well established in experimental systems of prostate cancer. AR is widely expressed in all subtypes of breast cancer (BC) and is considered to have context dependent role based on the steroid hormone microenvironment. Previous studies have shown AR as the only sex steroid receptor detectable in BC metastases and in metastatic lesion. We investigated the role of androgens in driving the EMT phenotype and association of AR induced genes with EMT in BC tumors using public dataset. Methods: We treated AR positive breast cancer cell line MDA-MB-453 with the androgen, dihydrotestosterone (DHT) followed by AR antagonist bicalutamide (Bic) and examined the expression levels of AR induced genes by quantitative real time PCR (qPCR) and AR induced protein GCDFP-15 by western blot. AR driven genes (SEC14L2, C1orf116, FKBP5, UGT2B11, UGT2B28, KCNMA1, PIP and ABCC11) were identified by bioinformatic pipeline using a systematic bioinformatic approach from public microarray data sets derived from AR positive breast cancer cell lines (S Rajarajan et al, SABCS 2021). Mesenchymal phenotype of the cell lines under DHT/Bic was evaluated morphologically and expression levels of EMT markers (ZEB1, Slug, Vimentin) and E-cadherin was estimated by qPCR, western blot and immunofluorescence. Migratory potential of the cell line under treatment was evaluated by wound healing assay and proliferation was examined by the MTT assay. Association of AR induced genes and levels of enzymes involved in intracrinal testosterone metabolism (SRD5A1 & SRD5A3) with EMT in breast tumors was evaluated using transcript data from METABRIC database. EMT scores were derived from previous publications (Byers et al, 2013, Mak et al, 2016) and correlation was tested with AR induced genes. Results: The MDAMB-453 cell line was treated with 10nM DHT for 72hrs and this increased the expression of AR downstream protein GCDFP-15 by 31.47% (p=0.022) when compared to the control. Further, a significant increase in the expression levels of AR driven genes with a fold change >2 was observed in the DHT treated cells (p< 0.05). The expression of GCDP15 protein (p=0.028) and the AR downstream genes (p< 0.05) were significantly repressed upon treatment with bicalutamide. DHT treatment also showed a significant higher expression of EMT master regulator, SLUG (fold change>3, p=0.045) and a wound healing assay showed a 22% increase in migration (p=0.027). The expression of SLUG was significantly repressed (p=0.003) and the migratory ability of the DHT treated cells reduced upon treatment with bicalutamide (p=0.145). We also observed a significant loss of E-cadherin protein (by 23.65%; p=0.024) with DHT treatment and this was completely reversed upon treatment with bicalutamide (p=0.047). No significant change in proliferation was observed among the different treatment conditions. A significant positive correlation was observed between AR induced genes and the EMT scores (p< 0.05). Expression level of SRD5A3 was also positively correlated with EMT score (p=0.043) and AR induced genes (p< 0.05), except SEC14L2. Conclusion: Androgen receptor plays an important role in the biology of breast cancer and is considered a useful marker for prognosis. However, antiandrogen therapies haven’t seen the expected success in clinical trial settings. Our results support the controversial role played by AR in higher androgenic environment within breast cancer and warrant the consideration of the intratumoral levels of sex steroid hormones. Citation Format: Savitha Rajarajan, Snijesh VP, Madhumathy G Nair, Apoorva D, Chandrakala M, Vidya P Nimbalkar, Maalavika Pillai, Mohit Kumar Jolly, Jyothi S Prabhu. Androgen mediated signaling induces epithelial to mesenchymal transition phenotype in MDA-MB-453 breast cancer cells and human breast tumors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-19-02.