Year: 2015
Type: article
Abstract: Cancer relapse is strongly associated with the presence of cancer stem cells (CSCs), which drive the development of metastasis and drug resistance.In human breast cancer, CSCs are identified by the CD44 + /CD24 -phenotype and characterized by drug resistance, high tumorigenicity and metastatic potential.In this study, I found that MCF-7/Adr cells that are breast cancer cells resistant to doxorubicin (Dox) uniformly displayed CSC surface markers, possessed CSC proteins, formed in vitro mammospheres, yet retained low migratory rate.They were also able to self-renew and differentiate under floating culture condition and are responsive to epigenetic drug treatment.High degree of DNA methylation (modifications of the cytosine residues of DNA) and histone deacetylation are major epigenetic landmarks of CSCs.In this work, I showed that MCF-7/Adr cells are sensitive to histone deacetylation inhibitor suberoylanilide hydroxamic acid (SAHA).Through RNA-sequencing technology, I also found that decitabine (DAC) and SAHA similarly affected a large number of the examined pathways, including drug and nanoparticle cellular uptake and transport, lipid metabolism, carcinogenesis and nuclear transport pathways.However, DAC significantly down-regulated several drug metabolism and drug resistant genes whereas SAHA showed no effect on them.iv siRNA therapy is the only approved genomic drug up to date; and is under clinical trials for cancer treatment.Cationic polymers are effective in complexing nucleotide through electrostatic interactions, forming polyplexes.Therefore, I further investigated the ability of a polyethyleneimine (PEI)-based cationic polymer, polyethylene glycol (Peg) modified L-arginine oligo (alkylaminosiloxane)-graft PEI ((P(SiDAAr) 5 Peg 3 ), in delivering siRNA.The delivery system enabled effective siRNA delivery in vitro.In vivo in xenograft tumor model, polyplex showed insignificant reduction in bioluminanance signal following single-dose intravenous administration than other control groups but the data were not statistically significant, suggesting that further dose optimization of polyplex required to achieve a greater effect.In a drug resistant cell line, the delivery system also enabled anti-ABCB1 siRNA to effectively knockdown its target ABCB1 protein and enhance the Dox uptake as well as its therapeutic efficacy.Furthermore, I conducted DNA-siRNA co-delivery using P(SiDAAr) 5 Peg 3 , and obtained significantly enhanced transfection levels for both DNA and siRNA using the co-delivery approach.In summary, this study identified stem-like characteristics in drug resistant cell line MCF-7/Adr, showed that epigenetic drugs DAC and SAHA are effective in targeting dug resistant cells, investigated the transcriptomic effects of DAC and SAHA through RNA sequencing, and developed a siRNA and DNA-co-siRNA delivery system that effectively transfected both metastatic and drug resistant breast cancer cell lines in vitro.vDEDICATION This dissertation is dedicated to my parents Li Wang and James Halpert, and my grandparents Guimin Wang and Fengxian Yang, for their support and unending encouragement.
Author: Shan Lu
Institution: University of Akron
Language: English
Topic: Cancer Cells and Metastasis
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2598768948