Date of Award

Spring 5-2024

Degree Type

Honors Thesis

Major

Biology

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Christina Tzagarakis-Foster

Second Advisor

Brian Thornton

Third Advisor

Scott Nunes

Abstract

The nuclear hormone receptor (NHR), DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1), is important in adrenal and gonadal development as well as steroidogenesis. It is encoded by the NR0B1 gene and functions mainly as a transcriptional repressor. Classified as an orphan receptor within the NHR superfamily, DAX-1 has been shown to inhibit other NHRs including estrogen receptor, androgen receptor and steroidogenic factor 1. DAX-1 is found to be underexpressed in breast and prostate cancers and, specifically in prostate cancer, is believed to be a transcriptional repressor of genes that are involved in epithelial-mesenchymal transition (EMT). EMT is a mechanism by which epithelial cells are able to assume a phenotype that allows them a degree of migratory capacity. Research has been conducted regarding the reintroduction of DAX-1 into CRISPR DAX-1 knockout (KO) prostate cancer cells, including analyzing DAX-1 and AR metastatic marker regulation following androgen stimulation. However, there is little research on the effect DAX-1 has on metastasis in adrenocortical carcinoma (ACC) cells, where it is overexpressed. This work investigates how DAX-1 modulates two metastatic markers in ACC cells: GATA6, a transcription factor involved in steroidogenesis, and ZEB1, a transcription factor that helps induce EMT in cancer cells. I investigated the relationship of DAX-1 with GATA6 and ZEB1 in SW13 cells, a human ACC cell line. I developed an RNAi knockdown model of DAX-1 to compare DAX-1’s modulation of metastasis against DAX-1 knockdown SW13 cells and wild-type SW13 cells. Wild-type SW13 qPCR results show DAX-1, ZEB1, and GATA6 expression in SW13 cells with a difference between ZEB1 and GATA6 levels. Following the DAX-1 knockdown by RNAi in SW13 cells, ZEB1 and GATA6 gene expression levels decreased in comparison to wild-type SW13 cells. A ChIP (chromatin immunoprecipitation) assay was also performed using the GATA6 promoter region where DAX-1 was found to be associated. These results currently indicate DAX-1 may act as a transcriptional activator of ZEB1 and GATA6, either directly or indirectly.

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