Date of Award

2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program

Pharmaceutical Sciences

Track

Medicinal Chemistry

Research Advisor

Michio Kurosu, PhD

Committee

Bernd Meibohm; Bob Moore, PhD; Isaac Donkor, PhD; Richard Addo, PhD

Keywords

Cytostatic, Cytotoxic, DPAGT1, Synthesis, Triple-negative breast cancer, Tunicamycin

Abstract

The tunicamycins have been broadly applied in research of N-linked glycosylation and protein misfolding fields. The tunicamycins display antiproliferative activity against a wide range of cancer and healthy cell lines with narrow therapeutic index. Cytotoxicity of the tunicamycins is believed to be the inhibition of dolichyl-phosphate N-acetylglucosamine-phosphotransferase 1 (DPAGT1), a transmembrane protein, in all mammalian cells in a non-selective manner. We have discovered a selective DPAGT1 inhibitor, APPB based on the non-cytotoxic natural product muraymycin A1. APPB inhibits migrations of solid cancers at low concentrations and induces apoptosis when increased dose concentrations. The observed anticancer profiles of APPB are completely different from those of the tunicamycins, thus, we hypothesized that cytotoxicity of the tunicamycins is unrelated to their inhibition of DPAGT1. To advance tunicamycin into a progressable drug lead, its promiscuous toxicities need to be attenuated. In addition, the discovery of chemically and metabolically stable tunicamycin analogs are essential. To this end, we have developed a super-efficient total synthesis of tunicamycin V and have established a method to identify selective DPAGT1 inhibitors based on tunicamycin cyclitol analogs. The complex pseudo-disaccharide and nucleoside segments are assembled in a one-pot Büchner-Curtius-Schlotterbeck reaction in a wet solvent system. A series of DPAGT1 inhibitors can be synthesized in 11-12 chemical steps from the commercially available starting material with high overall yields. The current lead TN-Cy-TBPA displays antimetastatic activity against triple-negative breast cancers, eventually inducing apoptosis. Unlike tunicamycin, TN-Cy-TBPA does not cause toxicity to healthy cells (even at 50 uM) and to mice (LD50 > 20 mg/kg (IV), ref. < 2.0 mg/kg for tunicamycin V). TN-Cy-TBPA salts can readily be dissolved in saline (ref. < 0.2 mg/mL for tunicamycin V). The pharmacokinetic data for TN-Cy-TBPA obtained using CD-1 mice revealed its drug-like properties. In this program, toxic tunicamycin V was successfully converted to potential pharmacological inhibitors of DPAGT1. Efficient and scalable syntheses of the tunicamycin cyclitol analogs are established for in vivo evaluations including toxicological studies.

Declaration of Authorship

Declaration of Authorship is included in the supplemental files.

ORCID

0000-0002-1745-2586

DOI

10.21007/etd.cghs.2024.0672

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