Semester

Summer

Date of Graduation

2013

Document Type

Dissertation

Degree Type

PhD

College

School of Medicine

Department

Microbiology, Immunology, and Cell Biology

Committee Chair

John Michael Ruppert.

Abstract

Detachment of epithelial cells from matrix or attachment to an inappropriate matrix engages an apoptotic response known as anoikis, which prevents metastasis. Anoikis-resistance of tumor cells is critical for anchorage-independent growth and metastasis. Here we show two novel oncogenic pathways that confer resistance to anoikis in tumor cells. One pathway (chapter 2) signifies a new link between EMT and anoikis-resistance. In chapter 3, we present a new connection between inflammatory signaling pathways and anoikis-resistance. Cellular sensitivity to anoikis is compromised during the oncogenic epithelial-to-mesenchymal transition (EMT), through various mechanisms. Chapter 2 introduces a novel mechanism (NRAGE/TBX2/p14ARF) that is induced upon loss of E-cadherin and EMT, mediating anoikis resistance. The inflammatory-response transcription factor, NF-kB, contributes to anoikis-resistance and metastatic progression, through mechanisms that are understood incompletely. Deleted in Breast Cancer (DBC1) is over-expressed in several tumor types and correlates with a poorer prognosis in some cases. DBC1 suppressed anoikis in normal epithelial and breast cancer cell lines. Chapter 3 introduces a novel mechanism: DBC1 suppresses anoikis through enhancing canonical NF-kB signaling. This study will provide mechanisms for DBC1 to act as a tumor promoter, by providing a link between inflammation and anoikis-resistance and providing a potential target for anti-NF-eB/anti-cancer drugs.

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