Author ORCID Identifier


Date of Graduation


Document Type

Dissertation (PhD)

Program Affiliation

Experimental Therapeutics

Degree Name

Doctor of Philosophy (PhD)

Advisor/Committee Chair

Don L. Gibbons

Committee Member

Andrew Gladden

Committee Member

Jichao Chen

Committee Member

Lauren Byers

Committee Member

Walter Hittelman

Committee Member

Varsha Gandhi


Lung cancer is a heterogeneous disease composed of genetically and phenotypically distinct tumor cells as well as a heterogeneous microenvironment consisting of non-cancer cells and extracellular matrix. Constant interactions among these components ultimately leads to a complex tumor tissue that is ever evolving and poses a therapeutic challenge for sustained benefit. Strategies for targeting lung cancers are largely guided by the genetic alterations identified in the tumor specimens. However, in order to gain a better understanding of lung cancer progression and develop effective treatment modalities, studying tumor in context of its microenvironment is crucial. The first aim of this project was to establish an experimental model to capture tumor heterogeneity. We developed an Ex Vivo Tumor system that preserved tumor composition and allowed the introduction of specific modifications in the tumor microenvironment to investigate their role in tumor progression. We utilized this system to demonstrate the role of extrinsic as well as intrinsic alterations that modify tumor cell behavior. Next, we explored the biological phenomenon epithelial-to-mesenchymal transition as a source of tumor cell heterogeneity and therapeutic resistance. Genetically identical KRAS mutant lung cancer cells displayed different phenotypic states that were associated with distinct survival pathways that allowed cancer cells to escape therapeutic targeting. With the use of extensive in vitro, ex vivo and in vivo models, we identified that a combinatorial approach of utilizing CDK4 and MEK inhibitors to effectively control tumor growth by targeting distinct tumor subpopulations within lung cancer and prevented emergent resistance to either single agent.


Lung cancer, heterogeneity, ex vivo tumors, CDK4 inhibitors, MEK inhibitors, EMT



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