ABSTRACT
BACKGROUND AND AIMS: Chronic liver disease (CLD) leads to approximately two million deaths annually. Cyclic adenosine monophosphate (cAMP) signaling has long been studied in liver injury, particularly in the regulation of fatty acid (FA) ß-oxidation and pro-inflammatory polarization of tissue-resident lymphocytes. Phosphodiesterase 4B (PDE4B) inhibition has been explored as a therapeutic modality, but these drugs have had limited success and are known to cause significant adverse effects. The PDE4 inhibitor 2-(4-([2-(5-Chlorothiophen-2-yl)-5-ethyl-6-methylpyrimidin-4-yl]amino)phenyl)acetic acid) (known as A-33) has yet to be explored for the treatment of metabolic diseases. APPROACH AND RESULTS: Herein, we evaluated the efficacy of A-33 in the treatment of animal models of alcohol-associated liver disease (ALD) and steatotic liver disease (SLD). We demonstrated that A-33 effectively ameliorated the signs and symptoms of CLD, resulting in significant decreases in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, decreased overall fat and collagen deposition in the liver, decreased intrahepatic triglyceride (TG) concentrations, and normalized expression of genes related to ß-oxidation of fatty acids, inflammation, and extracellular matrix (ECM) deposition. We also designed and synthesized a novel analog of A-33, termed MDL3, which inhibited both PDE4B and PDE5A and was more effective in ameliorating pathophysiological signs and symptoms of liver injury and inflammation. In addition, MDL3 re-sensitized obese mice to glucose and significantly inhibited the pathological remodeling of adipose tissue, which was not observed with A-33 administration. CONCLUSIONS: In conclusion, we synthesized and demonstrated that MDL3, a novel PDE4B and PDE5A inhibitor, presents a promising avenue of exploration for treating CLD.
ABSTRACT
Gemcitabine (GEM) is a nucleoside analogue approved as a first line of therapy for pancreatic ductal adenocarcinoma (PDAC). However, rapid metabolism by plasma cytidine deaminase leading to the short half-life, intricate intracellular metabolism, ineffective cell uptake, and swift development of chemoresistance downgrades the clinical efficacy of GEM. ONC201 is a small molecule that inhibits the Akt and ERK pathways and upregulates the TNF-related apoptosis-inducing ligand (TRAIL), which leads to the reversal of both intrinsic and acquired GEM resistance in PDAC treatment. Moreover, the pancreatic cancer cells that were able to bypass apoptosis after treatment of ONC201 get arrested in the G1-phase, which makes them highly sensitive to GEM. To enhance the in vivo stability of GEM, we first synthesized a disulfide bond containing stearate conjugated GEM (lipid-GEM), which makes it sensitive to the redox tumor microenvironment (TME) comprising high glutathione levels. In addition, with the help of colipids 1,2-dioleoyl-glycero-3-phosphocholine (DOPC), cholesterol, and 1,2-distearoyl-glycero-3-phosphoethanolamine-poly(ethylene glycol)-2000 (DSPE-PEG 2000), we were able to synthesize the lipid-GEM conjugate and ONC201 releasing liposomes. A cumulative drug release study confirmed that both ONC201 and GEM showed sustained release from the formulation. Since MUC1 is highly expressed in 70-90% PDAC, we conjugated a MUC1 binding peptide in the liposomes which showed higher cytotoxicity, apoptosis, and cellular internalization by MIA PaCa-2 cells. A biodistribution study further confirmed that the systemic delivery of the liposomes through the tail vein resulted in a higher accumulation of drugs in orthotopic PDAC tumors in NSG mice. The IHC of the excised tumor grafts further confirmed the higher apoptosis and lower metastasis and cell proliferation. Thus, our MUC1 targeting binary drug-releasing liposomal formulation showed higher drug payload, enhanced plasma stability, and accumulation of drugs in the pancreatic orthotopic tumor and thus is a promising therapeutic alternative for the treatment of PDAC.
