ABSTRACT
Successful treatment and diagnosis of neurological diseases depend on reliable delivery of molecules across the blood-brain barrier (BBB), which restricts penetration of pharmaceutical drugs and diagnostic agents into the brain. Thus, developing new noninvasive strategies to improve drug delivery across the BBB is critically needed. This study was aimed at evaluating the activity of HAV6 peptide (Ac-SHAVSS-NH2) in improving brain delivery of camptothecin-glutamate (CPT-Glu) conjugate and gadolinium-diethylenetriaminepentaacetate (Gd-DTPA) contrast agent in Sprague-Dawley rats. Brain delivery of both CPT-Glu and Gd-DTPA was evaluated in an in situ rat brain perfusion model in the presence and absence of HAV6 peptide (1.0 mM). Gd-DTPA (0.6 mmol/kg) was intravenously (iv) administered with and without HAV6 peptide (0.019 mmol/kg) in rats. The detection and quantification of CPT-Glu and Gd-DTPA in the brain were carried out by LC-MS/MS and quantitative magnetic resonance imaging (MRI), respectively. Rats perfused with CPT-Glu in combination with HAV6 had significantly higher deposition of drug in the brain compared to CPT-Glu alone. MRI results also showed that administration of Gd-DTPA in the presence of HAV6 peptide led to significant accumulation of Gd-DTPA in various regions of the brain in both the in situ rat brain perfusion and in vivo studies. All observations taken together indicate that HAV6 peptide can disrupt the BBB and enhance delivery of small molecules into the brain.
Subject(s)
Blood-Brain Barrier/metabolism , Brain/metabolism , Camptothecin/administration & dosage , Drug Delivery Systems , Gadolinium DTPA/administration & dosage , Glutamic Acid/administration & dosage , Peptide Fragments/administration & dosage , Animals , Blood-Brain Barrier/drug effects , Brain/drug effects , Chromatography, Liquid , Contrast Media/administration & dosage , Magnetic Resonance Imaging , Male , Rats , Rats, Sprague-Dawley , Tandem Mass SpectrometryABSTRACT
Inhibitor 2 of protein phosphatase 2A (I2PP2A), a biological inhibitor of the cellular serine/threonine protein phosphatase PP2A, is associated with numerous cellular processes that often lead to the formation and progression of cancer. In this study we hypothesized that targeting the inhibition of I2PP2A's multiple functions in prostate cancer cells might prevent cancer progression. We have investigated the effect of the small chain C6-ceramide, known to be a bioactive tumor suppressor lipid, on I2PP2A function, thereby affecting c-Myc signaling and histone acetylation in cells. Our data indicated that C6-ceramide treatment of prostate cancer cells induces cell death in PC-3, DU145, and LNCaP cells, but not normal prostate epithelial cells. C6-ceramide was able to disrupt the association between PP2A and I2PP2A. C6-ceramide inhibits I2PP2A's upregulation of c-Myc and downregulation of histone acetylation in prostate cancer cells. Our data indicated that targeting cancer related signaling pathways through I2PP2A using ceramide as an anti-I2PP2A agent could have beneficial effects as a therapeutic approach to prevent prostate cancer.
Subject(s)
Antineoplastic Agents/pharmacology , Ceramides/pharmacology , Histone Chaperones/metabolism , Prostatic Neoplasms/drug therapy , Transcription Factors/metabolism , Acetylation , Cell Line, Tumor , Cell Survival , Ceramides/metabolism , DNA-Binding Proteins , Epithelial Cells/metabolism , Gene Knockdown Techniques , Histone Chaperones/antagonists & inhibitors , Histone Chaperones/genetics , Histones/metabolism , Humans , Male , Molecular Targeted Therapy , Phosphoprotein Phosphatases/metabolism , Prostatic Neoplasms/metabolism , Protein Phosphatase 2C , Protein Processing, Post-Translational , RNA, Small Interfering/genetics , Transcription Factors/antagonists & inhibitors , Transcription Factors/geneticsABSTRACT
The transient-state kinetic approach reveals the formation and subsequent interconversions of intermediates in real time. Its potential for the mechanistic resolution of enzymatic and other complex chemical mechanisms has been severely limited however by the lack of a rigorous and applicable theoretical basis in contrast to that of the less direct but soundly based algebraic algorithms of the steady-state approach. Having recently established three rigorously derived fundamental "rules" of transient-state kinetics applicable to realistic multiple step reactions, we present here the successful application of the very counterintuitive "second rule" to the resolution of the mechanism of the l-phenylalanine dehydrogenase catalyzed reaction.
