Graduation Date

Spring 2023

Document Type


Degree Name

Doctor of Philosophy (PhD)


Pharmaceutical Sciences

First Advisor

Paul C. Trippier, Ph.D.

Second Advisor

Gargi Ghosal, Ph.D.

Third Advisor

Corey R. Hopkins, Ph.D.

Fourth Advisor

Jonathan L. Vennerstrom, Ph.D.


Batten Disease or Neuronal Ceroid Lipofuscinosis (NCL) is a group of rare, fatal, inherited pediatric neurodegenerative lysosomal storage disorders. NCLs are characterized by intracellular accumulation of an auto-fluorescent lipopigment called ceroid lipofuscin and neurodegeneration. Several forms of NCLs exist, some of which share some of the same features and symptoms but vary in severity and onset of symptoms with respect to age. Some common symptoms include progressive loss of vision, mental and motor deterioration, epileptic seizures, premature death, and in the rare adult-onset, dementia. Subtypes of NCLs occur when one of 13 different genes are mutated, and only two subtypes (CLN2 and CLN5) have approved clinical treatment options using gene therapy or enzyme replacement therapy. As CLN3 does not occur due to a loss-of-function mutation in an enzyme, genetic therapies are not an option. CLN3 is also linked to anti-apoptotic processes by modulation of Bcl-2. Thus, pharmacological intervention via small molecule therapeutics for treating CLN3 disease is an urgent and unmet need. Flupirtine is a non-opioid analgesic, in vitro and in vivo; it protects neuronal and photoreceptor cells from apoptosis. Known mechanisms of action for Flupirtine include upregulation of anti-apoptotic protein Bcl-2, protecting postmitotic neurons from death via increasing glutathione, activating an inwardly rectifying K+ channel, delaying loss of intramitochondrial membrane calcium retention capacity, and is an NMDA receptor antagonist. Flupirtine and aromatic carbamate derivatives possess anti-apoptotic properties and autophagy activation, which provide the basis for use as potential therapies in Batten disease. Several molecules were synthesized by modifying flupirtine/retigabine templates. Initial studies show that these compounds translate their neuroprotective effect to CLN3 patient induced pluripotent stem cell (iPSC)-derived neurons by activating autophagy, ameliorating induced apoptosis by Bcl-2, and rescuing mitochondrial dysfunction via enhancing the clearance of accumulated subunit c of ATP synthase.

Aldo-keto reductase 1 C3 (AKR1C3) is a key steroidogenic enzyme highly expressed in prostate cancer and some leukemias. AKR1C3 plays a vital regulatory role in cell proliferation, differentiation, and apoptosis of hematological malignant cells; it also catalyzes the formation of potent androgens responsible for tumor progression in prostate and other hormone-dependent cancers and can also contribute to drug resistance to a wide variety of cancer therapeutics. Studies have shown that upregulated expression of the AKR1C3 enzyme plays a role in mediating the resistance of specific tumor cells to various clinically available cancer therapeutics such as enzalutamide, cisplatin, and anthracyclines. The development of isoform-specific small molecule inhibitors of AKR1C3 could significantly potentiate the cytotoxicity of clinically available chemotherapeutics and is, thus, a promising target to counter drug resistance. Previously we have reported the most potent and selective AKR1C3 small molecule inhibitor. This inhibitor abolished the drug resistance of two chemotherapeutic agents used to treat prostate cancer. Proteolysis-targeting chimeras (PROTACs) are an emerging technology to bring about highly effective degradation of a protein of interest. Herein we report the discovery of a PROTAC based around a selective AKR1C3 inhibitor warhead, lenalidomide E3 ligase, and a triazole-based linker that induces significant degradation of AKR1C3 with concomitant amelioration of ARv7 expression in 22Rv1 prostate cancer cells, which outperforms a small molecule inhibitor. This is the first report of a PROTAC that degrades AKR1C3.


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