Cyclin-dependent kinases (CDKs) and cyclins (Cyclins) are the core molecules in the regulation mechanism of the entire cell cycle. Cell cycle dysregulation is a common feature of human cancers, and inhibitors of cyclin-dependent kinases (CDKs) play a crucial role in cell cycle control and are one of the most promising areas of cancer therapy. We aspired to use our cyclin-dependent kinase 8 (CDK8) inhibitor, Q-12, as a probe for biomarker discovery for CDK8 inhibitor sensitive tumor types. Q-12 shows potent inhibition of cell viability and induction of apoptosis process in some triple-negative breast cancer (TNBC) and colorectal cancer cell lines in vitro. Western blot results indicate that Q-12 decrease p-STAT3 (Ser 727) stabilized p-STAT3 (Tyr 705) cause its upregulation. Cytokines are responsible for the increased phosphorylation of STAT3 (Tyr 705). Q-12 inhibit phosphorylation of CDK8 substrates STAT3 (Ser 727), STAT1 (Ser 727), E2F1 (Ser375) and reduce CDK8 protein levels. Q-12 initially increase E2F1 protein levels activated E2F1 and decrease Mcl-1 protein levels. All results suggest that STAT3 may not play a major role in cell death mechanism while E2F1 may play a major role. The main aim of the study is to investigate CDK8 inhibitor Q-12 effects on CDK8 and CDK8 substrates in triple negative breast cancer cell line MDA-MB-468, in order to better understand the mechanism of anti-proliferative effect of Q-12.

Aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that regulates biological responses to planar aromatic hydrocarbon. AHR activates gene transcription by binding to its corresponding enhancer with its partner-aryl hydrocarbon receptor nuclear translocator (ARNT). In addition, this receptor has been shown to regulate xenobiotic-metabolizing enzymes such as cytochrome P450. AHR exists widely in body tissues and affects bioactivation of carcinogenic compounds, T cell differentiation, fatty acid synthesis, cell proliferation, hematopoietic stem cell differentiation, respiratory reactivity, and insulin sensitivity. Although the precise mechanism illustrating the endogenous AHR function remains unclear, there has been intense interest in exploring AHR as a potential target for the treatment of diseases such as cancer and autoimmune diseases. It is known that mouse ahr d-allele possesses low ligand-binding affinity, whereas mouse ahr b-allele has a higher ligand-binding affinity. The d-allele functions more similarly to human AHR than the b-allele, which is most commonly studied. Human AHR can be rather difficult to study since it is relatively unstable and less sensitive to some ligands in vitro. Thus we generated a deletion construct which has the ligand-binding domain of human AHR and hoped that the expression yield could be increased. Here, I present the process and the results of expressing the mouse full-length b-allele of AHR and the human AHR ligand binding domain (LBD, amino acids 108 to 400) in Pichia pastoris. A higher enrichment of the b-allele and LBD was observed in wild-type yeast (yJC100) strain when compared to the protease-deficient yeast (ySMD1163) strain. This observation was consistent with the increased copy number in the wild-type strain. Although the LBD transcript was detected in both the wild-type and protease-deficient strains, the LBD protein was only detected in the wild-type strain.

A series of 3-aminotetralins were synthesized as potential opioid antagonists. Each proposed target compound was based on a 3-(mono- or dialkylamino )-7 -(hydroxy or methoxy)-2, 2-dimethyl-1-tetralone parent structure. Three synthetic schemes were developed utilizing the common intermediate, ethyl3-benzylamino-2, 2-dimethyl-4-(4- methoxyphenyl)butyrate 3. In Scheme I, compound 3 was modified through a series of six steps to obtain 3-(N-methyl-N-cyclopropanecarboxamido )-7 -methoxy-2, 2-dimethyl- 1-hydroxy-1-phenyltetralin (9). To carry out further synthetic steps on the intermediate 9 required the reduction of the amide function, which proved to be problematic in terms of product isolation. Scheme II was a four-step procedure, which utilized the intermediate ethyl 3- amino-2, 2 dimethyl-4-(4-methoxyphenyl)butyrate (4), also utilized in Scheme I. Ester hydrolysis of the amino ester 4 produced the amino acid 12. Internal cyclization of 12 yielded the key intermediate, 3-amino-7 -methoxy-2, 2-dimethyl-1-tetralone (13). TheNalkylation step was carried out on 13 and this yielded the target compounds, 3-[N- ( cyclopropylmethyl)amino ]- and 3-[N, N-( dicyclopropylmethyl)amino ]-7 -methoxy-2, 2- dimethyl-1-tetralone (14, 15). Subsequently, compounds 14 and 15 were 0-demethylated to obtain the respective target compounds, 3-[N-(cyclopropylmethyl)amino]- and 3-[N, N-(dicyclopropylmethyl)amino ]-7-hydroxy-2, 2-dimethyl-1-tetralone (16, 17). Scheme III was an alternate synthetic route to obtain the target compounds 3-[Nmethyl- N-( cyclopropylmethyl)amino ]-2, 2-dimethyl-7-(hydroxy or methoxy)-1-hydroxy- 1-phenyltetralin (10, 11) without the amide reduction step required in Scheme I. The intermediate 3 was N-methylated to form the 3-N-methyl-N-benzylamino ester 18 by the Eschweiler-Clarke procedure. Compound 18 was converted through a series of four steps to obtain 3-[ N-methyl-N-( cyclopropylmethyl)amino ]-7 -methoxy-2, 2-dimethyl-1- tetralone (22), a target compound which was 0-demethylated to obtain compound 23, the 7-0H analog. The mono- and dialkylated 3-aminotetralins were synthesized and confirmed for purity and correct molecular formula by utilizing 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. The target compounds 14, 15, 16, 17,22 and 23 were converted to their salts and are being analyzed for opioid-related activity in receptor binding assays.

In the past decades, a series of small peptides, Protein Transduction Domain (PTD), were discovered to be able to facilitate the delivery of small proteins into living cells. With the specific feature, researchers have successfully delivered some functional proteins into living cells. To fully explore and understand the functions and structures of intracellular proteins, more powerful tools are under demand. Recently, an increasing number of rabbit monoclonal antibodies (RabMAbs) have been approved to able to recognize subtle distinctions between the changes of intracellular proteins status. They could be good tools for researchers with the ability to traverse through cell membrane into living cells. In this dissertation, a novel delivery technology for RabMAbs was established. Transcriptional activator of transcription (TAT) peptide was utilized as a delivery carrier for RabMAbs. It was demonstrated that RabMAbs could be delivered into living cells by conjugating with TAT peptide. Different cell lines, including adherent and suspension cells, were tested for the delivery of RabMAbs. The delivery process was studied in terms of incubation concentration and time, and an optimal delivery condition was established. To investigate the biological function of delivered RabMAbs inside cytoplasm, three RabMAbs against actin, procaspase-3 and NF-κB respectively were studied. Their binding activities after delivery were verified via sandwich-ELISA data. The immunofluorescent staining of the delivered RabMAb against actin showed it specifically bound to the actin filament in its native morphology. The quantitative analysis of the delivered RabMAb against procaspase-3 showed that approximately 60% of delivered antibody bound to the antigen proteins. The delivered RabMAb against NF-KB apparently blocked the nuclear translocation of NF-KB introduced by TNF-a. The success of delivering the three rabbit monoclonal antibodies with binding or inhibiting functions demonstrated the feasibility of delivering various RabMAbs into living cells by TAT peptide for studying the biological functions of intracellular proteins. Furthermore, to overcome the efficiency and cost issues of the RabMAb delivery system, a universal delivery platform for RabMAbs was developed. This platform uses goat-anti-rabbit polyclonal antibody conjugated with TAT peptide as delivery vehicle. It was confirmed that the goat-anti-rabbit polyclonal antibody modified with TAT peptide was able to capture RabMAbs and deliver RabMAbs into living cells by the conjugated TAT peptide. The results provide a promising delivery platform for all RabMAbs.

Microencapsulation of 5-fluorouracil was successfully accomplished with poly(ortho esters) polymer by emulsification-solvent evaporation method. While actual drug loading increased with increasing drug load (5 to 15% w/w), the entrapment efficiency remained essentially unaffected under a given set of experimental conditions. Incorporation of sorbitan sesquioleate enhanced entrapment efficiency, decreased the volume-surface mean diameter of the poly(ortho esters) microspheres and provided controlled release of 5-fluorouracil. The volume of aqueous phase was more important than the concentration of polyvinyl alcohol in it. The entrapment efficiency improved from 13 to 33% (w/w) when the volume of the aqueous phase was increased from 20 to 80 ml. The volume of organic phase (methylene chloride) and the concentration of polymer in it played an important role. The use of smaller volumes of more concentrated polymer solution enhanced actual drug loading and entrapment efficiency, and produced larger microspheres. The release of 5-FU from the microspheres prepared with sorbitan sequioleate was found to be nearly independent of the initial drug load with a mean zero-order rate constant of 0.0063 % per hr. The data suggested that drug release was largely a diffusional process with contributions from dissolution and polymer degradation.

Sucrose acetate isobutyrate (SAIB), a randomly substituted sucrose approximating sucrose diacetate hexaisobutyrate, is produced by Eastman Chemical Company for a variety of applications. SAIB is widely used in the food industry as a weighting agent to disperse flavoring oils in primarily citrus-based soft drink beverages. Additionally, SAIB is currently being marketed by another company as a parenteral drug delivery system. The studies reported here focused on investigating SAIB as an excipient, or delivery vehicle, for use in oral delivery of several drugs, including ibuprofen, saquinavir, and clarithromycin. Dissolution experiments were conducted using both ibuprofen and caffeine, and results suggest that SAIB can be used in dosage forms to control release rate. Pharmacokinetic studies in which laboratory rats were dosed with formulations containing drugs such as ibuprofen, saquinavir, and clarithromycin suggest that SAIB may act to reduce animal-to-animal variability in drug concentration profiles in some cases, and that it may also enhance gastroretention of the dosage forms. Finally, dosage form imaging studies suggest but do not reliably confirm that SAIB may aid in promoting gastric retention, which would make its use in dosage form formulation beneficial for administration of drugs whose action is intended to occur in the stomach.

This project describes the development of a new antitumor therapeutic platform that combines the benefits of small-molecule drug conjugates (SMDCs) and antibody drug conjugates (ADCs). Valine-citrulline (VCit) dipeptide linkers are popular cathepsin B cleavable ADC linkers. Due to its instability in mouse serum, translating efficacy data from mouse to human is more difficult. It has been reported that replacing the VCit linker with glutamic acid-valine-citrulline (EVCit) improves ADC stability in mouse serum. The effect of the EVCit linker on the stability of SMDCs has not been reported so far. In a xenograft mouse model of prostate cancer, we found that incorporating the EVCit linker in PSMA-targeting SMDCs equipped with the transthyretin ligand AG10 resulted in conjugates with lower toxicity, extended half-life, and superior therapeutic efficacy compared to the standard metastatic castration-resistant prostate cancer (mCRPC) treatment option, docetaxel. This should improve the predictability of SMDC preclinical toxicity and efficacy data from mice.

This thesis describes the development of a way to study the N8 - acetylspermidine deacetylase enzyme activity. The method created in this thesis emphasizes sensitivity, accuracy and safety. In this study, HeLa cells were cultured and extracted to yield a crude N8 - acetylspermidine deacetylase enzyme mixture. By measuring the decrease of N8 - acetylspermidine and the increase of spetmidine, N8 -acetylspermidine deacetylase enzyme activity can be determined using either a Varian 1200L LC/MS/MS or an API 3000 LC-ES (+)/MS/MS. An acetylation-derivatization method was developed because N8 -acetylspermidine and spermidine are hard to purify from a biological sample since they are not retained on a CIS solid phase extraction column or on a RP HPLC (high performance liquid chromatography) reverse phase column due to their small molecular weight and high polarity. The quantitation of N8 -acetylspem1indine over the range 2ng/ul to 5pg/ul was fit by linear regression as y = 1.064x + 0.218 with an R-squared value of 0.9996, where y is the peak area of the fragment-ion SRM (selected reaction monitoring: m/z: 188/114) chromatograms from N8 -acetylspermindine and x is the concentration of N8 - acetylspermindine. Acetylation of spermidine (SPD) and N8-acetylspermidine (N8AcSPD) with d6-acetic anhydride produces the d9 labeled triacetylated derivative of SPD and d6 labled triacetylated spermidine derivative of N8AcSPD. These triacetylated forms are retained on a C18 column. MS/MS gives characteristic m/z fragment ions for the derivatized species: N8AcSPD (278 to 215), NlAcSPD (278 to 218) and SPD (281 to 218). The fragment-ion SRM (selected reaction monitoring) chromatograms are used for the quantitation. A plot of peak area ratios for known mixtures of N8AcSPD and total SPD versus the molar ratios of N8AcSPD and total SPD was found to fit a linear regression line withy= 0.705x + 0.035 with an R-squared value of 0.9919. Quantitation of d6- and dg-tri-acetylspermidine by LC/MS/MS is possible at the low levels of materials found in cell extracts since the separation method results in a lower limit of quantitation. This approach enables the study of N8 - acetylspermidine deacetylase enzyme activity.

Resveratrol and catechin have behavioral and neuroprotective effects that may be due to their interaction with neuronal ion channels. It was hypothesized that the grape compounds, resveratrol and catechin modulate GABAAA receptors. To address this hypothesis, the effects of resveratrol and catechin were investigated on human recombinant GABAA receptors expressed in HEK-293 cells using electrophysiological techniques.<.p> HEK-293 cells were cultured and transfected using eDNA encoding human GABAA receptors. GABA-evoked currents were recorded from HEK cells 24-48 hours following transfection. Cells were voltage clamped in the whole cell configuration at -60mV using the patch-clamp technique. Ligand-activated currents were recorded and stored, using Win WCP software, on a desktop computer. Resveratrol (1- 100μM) dose-dependently potentiated GABA-evoked currents recorded from α1β2< /sup>γ2 and α1β2 GABAA receptors. Resveratrol did not modulate a α1β2< /sup>γ2 and α1β2 GABAA receptors. Furthermore, resveratrol did not act through the benzodiazepine binding site. The low efficacy and subunit selectivity of resveratrol is a promising discovery for the development of a highly specific GABAergic modulator. Conversely, catechin (1-100αM) dose-dependently inhibited GABA-evoked currents recorded from α1β2 and α1β1 GABAA receptors. The degree of inhibition was the same for both receptor subtypes. Catechin did not modulate α1β2γ2 or α1β1γ2 GABAA receptors. The selectivity of catechin for receptors lacking the γ subunit is similar to the effects of zinc and did not involve the benzodiazephine site on GABAA receptors. This study has shown that catechin and resveratrol are subunit-selective modulators of human GABAA receptors. These compounds could lead to the development of novel agents to be used in treating neurological disorders. These data support the use and study of natural products for the development of agents that act selectively on the nervous system.

Development of liposome formulation of an amphiphilic anticancer peptide using the ANTS/DPX leakage assay. The effects of lipid composition on the liposomes' resistance to an amphiphilic cyclic peptide c[KS.S.S.KWL W] were studied by the ANTS/DPX leakage assay. One or more unsaturated acyl chains in the phospholipids, small phospholipid headgroup size, the presence of cholesterol, and the presence of PEG-lipid were demonstrated as critical parameters to stabilize the liposome membrane. A liposome formulation of the peptide comprising POPE/POPC/cholesterol/C16 mPEG 2000 ceramide (20.8:31.2:40:8, mol%) was thereby developed with a peptide-encapsulation efficiency of 47.8%. The liposomal cyclic peptide exhibited dose-dependent toxicity to MCF7 human breast cancer cells and stability under incubation. Design, construction and in vitro characterization of a hydrazone-based convertible liposomal system for anticancer drug delivery. A novel PEG-lipid, PEG2ooo-Hz-DHG, with an acid-labile hydrazone linker between the PEG2ooo head group and the lipidic DHG moiety was synthesized. PEG2000-Hz-DHG was relatively stable at normal physiological pH 7.4, but hydrolyzed more quickly at tumor interstitium pH 6.5-7.0 and endosomal/lysosomal pH 5.0. A novel pH-sensitive "Convertible Liposome System" (CLS) was constructed comprising PEG2ooo-Hz-DHG, positively charged lipid DOTAP, and the zwitterionic phospholipid POPC (8:15:77, mol%). CLS converted from neutrally charged "stealth" liposome to positively charged liposome at tumor interstitual pH owing to the hydrolysis ofPEG2ooo-Hz-DHG. The doxorubicin-encapsulated CLS that had been pre-incubated at pH 6.5 for 30 h exhibited more intensive binding and higher toxicity to Bl6-Fl0 murine melanoma and MDA-MB-435S human breast cancer cells than doxorubicin encapsulated in pH-insensitive stealth liposome.