Targeting GRP78 in Cancer with Nucleic Acid Bioconjugates

Nucleic acid bioconjugates have gained widespread use in medicinal chemistry research programs aimed at fighting human malignancies such as cancer, diabetes, genetic and infectious diseases. Their popularity stems from their ability to accelerate the drug development process by conjugating chemical functionality that may improve the pharmacology of a bioactive nucleoside. Moreover, this strategy has been proven to be effective with small molecule nucleoside analogs and those derived from lengthy oligonucleotide sequences. Considering these fruitful applications, my research and this thesis aims to explore the synthesis, characterization and therapeutic potential of novel classes of nucleic acid bioconjugates. These are based on, aminoacyl nucleolipids, from which a simple, versatile and efficient synthesis strategy has been developed for this new class of DNA binding molecules as described in Chapter 2 of this thesis. This bioconjugate exhibited GRP78 oncogene binding affinity (KD: 0.25 mM) as characterized by PAGE gel shift assays. Its binding affinity towards the GRP78 oncogene was also confirmed using circular dichorism spectroscopy, and thermal denaturation experiments. Moreover, dynamic light scattering experiments also demonstrated increases in particle sizes after binding of this molecule to the GRP78 oncogene. In a single dose (10 µM) screen against a panel of 60 cancer cell lines, the aminoacyl nucleolipid demonstrated selective anti-leukemic activity, highlighting its potential in anti-cancer research programs. In Chapter 3, the synthesis, biophysical properties and GRP78 DNA cleavage activity of a phthalocyanine-linked oligonucleotide will be highlighted for photodynamic oncogene therapy applications. The synthesis and characterization of cancer-targeting oligonucleotide (CTO) and its bio-conjugation to a chemically resilient photosensitizer, a carboxy-derived perfluorophthalocyanine (Pc), enabled the production of a unique bioconjugate for potential anti-cancer applications. In this study, the Pc-CTO demonstrated the ability to hybridize to complementary GRP78 DNA and mRNA oncogenes. In a photochemical oxidative cleavage assay, the Pc-CTO triggered significant degradation of the GRP78 oncogenes underscoring its potential in GRP78-targeting photodynamic therapy. In Chapter 4, a study into the design, synthesis and structure-function relationships of a new class of nucleic acid bioconjugates is presented. The diacylhydrazine-linked dinucleosides represent a novel class of nucleic acid bioconjugates that are proposed to improve the structural stability of turn conformations in DNA or RNA hairpin secondary structures. My advances in the synthesis, structure elucidation and biological evaluation of these putative hairpin mimics will be described. In sum, this thesis will serve to highlight my contributions to the flourishing field of nucleic acid bioconjugation for GRP78-targeting for anti-cancer applications