Grainyhead like 2 (GRHL2) is an essential transcription factor for development and function of epithelial tissues. It has dual roles in cancer by supporting tumor growth while suppressing... Show moreGrainyhead like 2 (GRHL2) is an essential transcription factor for development and function of epithelial tissues. It has dual roles in cancer by supporting tumor growth while suppressing epithelial to mesenchymal transitions (EMT). GRHL2 cooperates with androgen and estrogen receptors (ER) to regulate gene expression. We explore genome wide GRHL2 binding sites conserved in three ER?/GRHL2 positive luminal breast cancer cell lines by ChIP-Seq. Interaction with the ER?/FOXA1/GATA3 complex is observed, however, only for a minor fraction of conserved GRHL2 peaks. We determine genome wide transcriptional dynamics in response to loss of GRHL2 by nascent RNA Bru-seq using an MCF7 conditional knockout model. Integration of ChIP- and Bru-seq pinpoints candidate direct GRHL2 target genes in luminal breast cancer. Multiple connections between GRHL2 and proliferation are uncovered, including transcriptional activation of ETS and E2F transcription factors. Among EMT-related genes, direct regulation of CLDN4 is corroborated but several targets identified in other cells (including CDH1 and ZEB1) are ruled out by both ChIP- and Bru-seq as being directly controlled by GRHL2 in luminal breast cancer cells. Gene clusters correlating positively (including known GRHL2 targets such as ErbB3, CLDN4/7) or negatively (including TGFB1 and TGFBR2) with GRHL2 in the MCF7 knockout model, display similar correlation with GRHL2 in ER positive as well as ER negative breast cancer patients. Altogether, this study uncovers gene sets regulated directly or indirectly by GRHL2 in luminal breast cancer, identifies novel GRHL2-regulated genes, and points to distinct GRHL2 regulation of EMT in luminal breast cancer cells. Show less
The objective of this study was to investigate the expression and function of GRHL2 in different breast cancer subtypes. In Chapter 2, we focused on the expression of GRHL2 in human breast cancer... Show moreThe objective of this study was to investigate the expression and function of GRHL2 in different breast cancer subtypes. In Chapter 2, we focused on the expression of GRHL2 in human breast cancer and the distinct effects of GRHL2 knockout on aspects of growth versus migration in basal A and luminal-like subtypes. In Chapter 3, ChIP-seq was used to explore the genomic landscape of GRHL2 binding sites in basal A and luminal-like subtypes of breast cancer and this data was used to predict shared and distinct GRHL2 target genes. In Chapter 4, based on a conditional GRHL2 knockout system, we determined the dynamic changes in genome-wide DNA transcription triggered by loss of GRHL2 in luminal-like breast cancer cells and used the data to predict affected pathways. In Chapter 5, ChIP-seq and BrU-seq data were integrated to identify genes whose transcription is controlled by GRHL2 and establish gene expression networks regulated by GRHL2 in luminal-like breast cancer. Show less
