Characterization Of The Role Of Klf9 Transcription Factor In Breast Cancer Estrogen Response

Kruppel-like factor 9 (KLF9) is a member of the KLF family of transcription factors. Previous studies report significant KLF member involvement in breast cancer estrogen response, notably KLF4 [1, 2] and KLF5 [3, 4]. KLF9 has been shown in uterine cancer cells to function as an estrogen-dependent regulator of the estrogen response pathway [5]. We aim to evaluate the role of KLF9 in breast cancer cell estrogen response. We have performed studies demonstrating that KLF9 exhibits an early-activated estrogen response. Five sites have been identified upstream of the KLF9 gene that interact with estrogen receptor alpha (ERα) [6-8]; we observe ERα enrichment at three of these sites that is estradiol-dependent. Though KLF9 has been shown to act as an essential element in estrogen response in the uterus, KLF9 response in breast cancer cells has yet to be characterized. To study the role of KLF9 in estrogen-mediated responses in transcriptional and proliferative activity, we have manipulated the level of KLF9 expression in MCF-7 breast cancer cells. These cells have been shown to exhibit a clear transcriptional response to estradiol in luciferase reporter assays. We have optimized RNAi conditions to achieve significant knockdown of the KLF9 gene in MCF-7 cells. Additionally, we have produced and tested a KLF9 overexpression vector construct that significantly upregulates expression of KLF9 in this cell line. These tools will be used to more extensively characterize the role of KLF9 in MCF7 cell estrogen-stimulated transcription and proliferation. We are measuring transcriptional response to estrogen signaling with luciferase reporter assays and estrogen stimulated cell proliferation with BrdU proliferation assays. Elucidating KLF9 involvement in E2-mediated breast cancer cell signaling and response, therefore, is an important component of understanding of the regulatory mechanisms behind estrogen response in breast cancer. 1. Akaogi K et al. (2009). Oncogene 28(32): 2894. 2. Quintana AM et al. (2011). BMC Cancer 11: 30. 3. Guo P et al. (2010). International Journal of Cancer 126(1): 81. 4. Zhao KW et al. (2011). Biochemical Journal 437(2): 323. 5. Velarde MC et al. (2007). Molecular Endocrinology 21(12): 2988. 6. Carroll JS et al. (2006). Nature Genetics 38(11): 1289. 7. Hua S et al. (2008). Molecular Systems Biology 4:188. 8. Fullwood MJ et al. (2009). Nature 462(7269): 58. 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 67. doi:1538-7445.AM2012-67