By a News Reporter-Staff News Editor at Biotech Week -- Data detailed on Apoptosis have been presented. According to news reporting out of San Juan, Puerto Rico, by NewsRx editors, research stated, "Cytochrome c (Cyt c) is a small mitochondrial heme protein involved in the intrinsic apoptotic pathway. Once Cyt c is released into the cytosol, the caspase mediated apoptosis cascade is activated resulting in programmed cell death."
Our news journalists obtained a quote from the research from the University of Puerto Rico, "Herein, we explore the covalent immobilization of Cyt c into mesoporous silica nanoparticles (MSN) to generate a smart delivery system for intracellular drug delivery to cancer cells aiming at affording subsequent cell death. Cyt c was modified with sulfosuccinimidyl-6-[3'-(2-pyridyldithio)-propionamido] hexanoate (SPDP) and incorporated into SH-functionalized MSN by thiol-disulfide interchange. Unfortunately, the delivery of Cyt c from the MSN was not efficient in inducing apoptosis in human cervical cancer HeLa cells. We tested whether chemical Cyt c glycosylation could be useful in overcoming the efficacy problems by potentially improving Cyt c thermodynamic stability and reducing proteolytic degradation. Cyt c lysine residues were modified with lactose at a lactose-to-protein molar ratio of 3.7 +/- 0.9 using mono(lactosylamido)-mono(succinimidyl) suberate linker chemistry. Circular dichroism (CD) spectra demonstrated that part of the activity loss of Cyt c was due to conformational changes upon its modification with the SPDP linker. These conformational changes were prevented in the glycoconjugate. In agreement with the unfolding of Cyt c by the linker, a proteolytic assay demonstrated that the Cyt c-SPDP conjugate was more susceptible to proteolysis than Cyt c. Attachment of the four lactose molecules reversed this increased susceptibility and protected Cyt c from proteolytic degradation. Furthermore, a cell-free caspase-3 assay revealed 47% and 87% of relative caspase activation by Cyt c-SPDP and the Cyt c-lactose bioconjugate, respectively, when compared to Cyt c. This again demonstrates the efficiency of the glycosylation to improve maintaining Cyt c structure and thus function. To test for cytotoxicity, HeLa cells were incubated with Cyt c loaded MSN at different Cyt c Concentrations (12.5, 25.0, and 37.5 mu g/mL) for 24-72 h and cellular metabolic activity determined by a cell proliferation assay. While MSN-SPDP-Cyt c did not induced cell death, the Cyt c-lactose bioconjugate induced significant cell death after 72 h, reducing HeLa cell viability to 67% and 45% at the 25 mu g/mL and 37.5 mu g/mL concentrations, respectively. Confocal microscopy confirmed that the MSN immobilized Cyt c-lactose bioconjugate was internalized by HeLa cells and that the bioconjugate was capable of endosomal escape."
According to the news editors, the research concluded: "The results clearly demonstrate that chemical glycosylation stabilized Cyt c upon formulation of a smart drug delivery system and upon delivery into cancer cells and highlight the general potential of chemical protein glycosylation to improve the stability of protein drugs."
For more information on this research see: Delivery of Chemically Glycosylated Cytochrome c Immobilized in Mesoporous Silica Nanoparticles Induces Apoptosis in HeLa Cancer Cells. Molecular Pharmaceutics, 2014;11(1):102-111. Molecular Pharmaceutics can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Molecular Pharmaceutics - www.pubs.acs.org/journal/mpohbp)
Our news journalists report that additional information may be obtained by contacting J. Mendez, University of Puerto Rico, Dept. of Chem, San Juan, PR 00931, United States. Additional authors for this research include M.M. Cruz, Y. Delgado, C.M. Figueroa, E.A. Orellano, M. Morales, A. Monteagudo and K. Griebenow (see also Apoptosis).
Keywords for this news article include: Cancer, Therapy, San Juan, Caspases, Oncology, Apoptosis, Hela Cells, Puerto Rico, Cytochromes, Hemeproteins, Nanoparticle, United States, Nanotechnology, Peptide Hydrolases, Drug Delivery Systems, Emerging Technologies, Enzymes and Coenzymes, Cysteine Endopeptidases, North and Central America
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