Biomedical Sciences ETDs

Publication Date

Summer 7-12-2019

Abstract

Evasion of apoptosis and resistance to chemotherapy are major therapeutic challenges for acute leukemias. Presumably as a means to promote cell survival, multiple elements of the cyclic AMP (cAMP) pathway are aberrantly regulated in acute leukemias. Furthermore, increased intracellular cAMP (icAMP) is known to induce apoptosis. Therefore, modulation of icAMP has long been a target in leukemias. The central hypothesis of this dissertation is that malignant cells produce and remove excess intracellular cAMP to evade apoptosis and promote survival. Consequently, inhibition of cAMP efflux could selectively trigger leukemia cell death. We designed a novel assay to assess icAMP efflux from cells, and used this in a high throughput screen to identify several molecules as inhibitors of cAMP efflux (ICE). We determined that cAMP efflux mechanisms are relatively absent in normal peripheral blood mononuclear cells (PBMCs), but are active in leukemia cell lines. We also validated the ability of ICE to increase cAMP pathway activity. We demonstrated that ICE selectively induce apoptosis in leukemia cells. Because chemotherapy resistance can occur by cAMP efflux transporters, this dissertation also addresses the possibility of using ICE in combination with current therapeutics. We demonstrate that combinations of ICE with leukemia chemotherapeutic agents produce synergistic effects against acute leukemia cells in vitro and ex vivo. In conclusion, we believe that our data support inhibition of efflux as a mechanism in cAMP pathway targeting that merits further investigation for the development of cancer therapeutics.

Keywords

ABC transporters, acute leukemia, cyclic AMP, cAMP, efflux, drug discovery, high-throughput flow cytometry

Document Type

Dissertation

Language

English

Degree Name

Biomedical Sciences

Level of Degree

Doctoral

Department Name

Biomedical Sciences Graduate Program

First Committee Member (Chair)

Larry A. Sklar

Second Committee Member

Alexandre Chigaev

Third Committee Member

Ksenia Matlawska-Wasowska

Fourth Committee Member

Bruce S. Edwards

Fifth Committee Member

Bridget S. Wilson

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