Date of Award

1-1-2021

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Biomedical Sciences

Content Description

1 online resource (xix, 112 pages) : illustrations (chiefly color)

Dissertation/Thesis Chair

Jason I Herschkowitz

Committee Members

Douglas S Conklin, JoEllen Welsh, Valerie J Bolivar, Thomas Begley

Keywords

Breast Cancer, Epithelial to mesenchymal transition, LncRNA AK001796, Long non-coding RNAs, Metastasis, PARP1, Breast, Non-coding RNA, Epithelium, Mesenchyme

Subject Categories

Biology | Medicine and Health Sciences

Abstract

Long noncoding RNAs (lncRNAs) are emerging as key molecules regulating several cellular pathways and contributing to the development and progression of different diseases including cancer. The epithelial-to- mesenchymal transition (EMT), a molecular reprogramming process that plays a critical role in cancer metastasis, involves a complex interaction between protein coding and non-coding transcripts including lncRNAs. Understanding the biological significance of those lncRNAs of relatively unknown function, may help to uncover potential therapeutic targets for the aggressive subtypes of breast and other cancers. In this study, we examined the expression profiles of more than 17,000 lncRNAs in a large set of patients’ derived breast cancers and have identified a lncRNA, AK001796, that is highly enriched in aggressive breast cancers and in several induced models of EMT. Interestingly, knockdown of this lncRNA in triple-negative breast cancer (TNBC) cell lines showed a concomitant increase in the epithelial phenotype-associated gene E-cadherin, while overexpression of AK001796 is associated with suppression of E-cadherin and upregulation of the mesenchymal markers TWIST and vimentin. Loss-of-function studies using modified antisense oligonucleotides (ASOs) suggests that this lncRNA may be a crucial player for cell viability in EMT-positive breast cancer. Further, molecular characterization of this lncRNA revealed it to be regulated by the EMT-associated transcription factor BHLHE40. To identify potential target genes for AK001796, we investigated its association with the nearby gene, BCL2L11, an apoptosis-associated protein. Interestingly, silencing of AK001796 resulted in upregulation of BCL2L11. In order to elucidate the mechanism of action of AK001796, we pulled-down an interacting protein partner, poly ADP-ribose polymerase enzyme (PARP1) and modulated its enzymatic activity. These findings suggest AK001796 is a potential therapeutic target for metastatic breast cancer.

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