Abstract
Cisplatin and other platinum(II)-based anticancer drugs have been widely used for cancer therapy, however, the clinical application of the platinum anticancer drugs is limited by low solubility, drug resistance, and dose-limiting side effects, partially owing to their poor selectivity for cancerous tissues over normal tissues. Targeting and delivery of platinum-based drugs specifically to cancer cells is a promising approach to avoid the normal tissue damage and drug resistance. In this dissertation work, a series of novel platinum(II)-based anticancer agents and targeted conjugates have been developed. The complexes contain: 1) two amino ligands, 2) mono- or bis- carboxylate ligand replacing the chloride ligands; 3) an uncoordinated carboxyl group/hydroxyl groups for conjugation with other functional moieties. These new platinum complexes displayed much better water solubility and much higher efficacy than carboplatin towards a broad spectrum of tumor cells. These new platinum complexes bind DNA rapidly and induce apoptosis in cancer cells. A few of the promising new platinum(II) complexes were successfully conjugated to an HER2-targeting peptide to target HER2 receptor which is overexpressed in a broad range of human cancers. The targeted conjugates displayed targeting capability towards HER2 positive breast cancer cell models. The second part of the dissertation focused on developing novel bioimaging techniques to monitor CDKL5 protein and its pathogenic variants which cause CDKL5 disorder. CDKL5 deficiency disorder (CDD) is a rare developmental epileptic encephalopathy (DEE), which typically presents early-onset epileptic encephalopathy, infantile spasms, and severe intellectual disability. Despite evidence indicating that CDKL5 is involved in normal brain development, the physiological function of the CDKL5 protein and its pathogenic variants remain poorly understood. The incorporation of fluorescent unnatural amino acids at specific sites into proteins via genetic code expansion may provide a novel live-cell imaging tool for the study of protein expression, dynamics and function in real-time. In this study, a coumarin-based fluorescent amino acid (Cou-AA) was incorporated into CDKL5 and its pathogenic variants to create fluorescent CDKL5s via the amber suppression method. These fluorescent CDKL5s were successfully employed as fluorescent imaging trackers to investigate the expression, subcellular localization, and trafficking of the wild-type and distinct pathogenic CDKL5 proteins in live-cells. This approach has revealed an abnormal subcellular localization pattern for a frameshift CDKL5 mutant, thereby providing new insights into the molecular pathogenicity of CDD.