Dissertations, Theses, and Capstone Projects

Date of Degree

9-2025

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy

Program

Biology

Advisor

Karen Hubbard

Committee Members

Shubha Govind

Maria Contel

Shireen Saleque

Hanna Irie

Subject Categories

Cancer Biology

Keywords

Breast cancer, Triple negative breast cancer, Ru-IM, epigenetic, reactive oxygen species, inflammation

Abstract

Triple negative breast cancer (TNBC) is an aggressive and heterogeneous molecular subtype of breast cancer that has limited available treatments. The organometallic cationic ruthenium derivative Ru-IM was found to be highly water soluble, was differentially toxic for breast cancer cells and tumors, and was involved in the pI3K/AKT/mTOR pathway. However, a full understanding of genetic and epigenetic factors that can be part of regulatory mechanisms of Ru-IM is yet to be determined. Epigenetic assays including DNA methylation, histone acetylation and histone deacetylation were performed with the half inhibitory concentration (IC50) values of Ru-IM. Bisulfite sequencing of untreated and treated MDA-MB-231 and HCC1806 cell lines revealed no difference in global DNA methylation but specific genes appear to be differentially altered. Validation of some genes in important cancer-related pathways showed that Ru-IM may potentially affect some gene expression via DNA methylation. Interestingly, Ru-IM treatment did not significantly change global hydroxymethylation but the gene expression of TET1 slightly decreased while TET2 and TET3 increased. In addition, Ru-IM did significantly change global histone acetylation enzymatic activity while global histone deacetylation activity was not significantly affected. Although Ru-IM induces reactive oxygen species (ROS), oxidized DNA stress levels remain unchanged between untreated and Ru-IM treatment using 8-Hydroxydeoxyguanosine assay, supporting the idea that Ru-IM does not bind DNA as its mode of action. We have tested the effect of the ROS inhibitor, N-acetyl cysteine, NAC, on the expression levels of specific genes in inflammatory pathway and MAPK. NAC treatment showed that these genes may have been activated by ROS. Taken together, the studies presented here should shed light on the role that epigenetics and oxidative stress contribute to the mechanisms that Ru-IM exerts as a potential chemotherapeutic.

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