Date of Award

Fall 12-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program/Concentration

Biomedical Sciences - Bioelectrical Science

Committee Director

Stephen J. Beebe

Committee Member

Lesley H. Greene

Committee Member

Siqi Guo

Committee Member

Piotr Kraj

Abstract

Cancers remain in the top noncommunicable diseases responsible for premature mortality. The heterogeneity among cancers and within tumors makes treating them ever more challenging. Our misfortune for developing cures is mocked by cancer, with the lowest probability of success (PoS) through clinical trials and FDA approval. At the basic level, there are generally two broad gaps impeding cancer eradication: the unidentified shared mechanism(s) exploited by all cancers and the therapeutic approach to intervene. Nanosecond pulse stimulation (NPS) offers a unique approach since its broad impacts intersect those often hijacked by oncogenesis. Metabolic pathways, known for dysfunctions among cancers, share a common intersection at the mitochondria, where signaling molecules impact cellular homeostasis. The concept of immunometabolism recognizes shifts in metabolism coincide with phenotypic expression of certain immune cells. Thus, the effects of NPS were investigated in vitro for mechanistic impacts on mitochondria and in vivo for efficacy, immunity, and immunometabolism.

In vitro, the NPS-induced dissipation of the mitochondrial membrane potential (Δ𝛹m), a determinant of mitochondrial fitness, was probed for calcium dependence, mitochondrial reactive oxygen species (mROS) generation, and sensitivity to cyclophilin D inhibition (CypD) by cyclosporin A. The results showed that Δ𝛹m dissipation was calcium and mROS dependent and sensitive to CypD inhibition, indicating that NPS activated the permeability transition pore, known for its physiological role in cellular homeostasis.

In vivo, the efficacy of NPS induced tumor regression was cancer type dependent since in some cancer models it was more (murine breast cancer) or less (murine melanoma) successful at inducing primary tumor clearance and protection. Thus, the NPS induced effects on immunity and the immunometabolism of CD4+ T cells were investigated in the murine B16-F10 melanoma model. The results indicated that while NPS indeed induced an immune response, the persistence of suppressor cells was likely responsible for the lack of efficacy. Furthermore, in vivo NPS induced metabolic reprogramming of CD4+ T cells which was supported phenotypically. These were the first investigations into the NPS induced effects on immunometabolism.

DOI

10.25777/ra5e-1a72

ISBN

9798780600213

ORCID

0000-0002-0672-2202

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