Protective effect of colostrinin on neuroblastoma cell survival is due to reduced aggregation of beta-amyloid.
Colostrinin (CLN), a mixture of proline-rich polypeptides, has shown a stabilizing effect on cognitive function in Alzheimer's patients measured by the Alzheimer's disease Assessment Scale-cognitive (ADAS-cog) and in Instrumental Activities of Daily Living (ILDL) in recently conducted clinical trials. The aim of this study was to elucidate a possible mode of action of CLN in the treatment of Alzheimer's disease. Here, we report that CLN prevents the aggregation of beta-amyloid peptide Abeta (1-40) in vitro. The impact of CLN on the fibril formation was monitored by optical and electron microscopy. The electron micrographs illustrate that, at 25 microM, Abeta (1-40) peptides formed fibrils after 24-48 h of incubation. The presence of 0.25 microM CLN completely abolished the fibril formation. Abeta (1-40) peptides grow into dense fibers when examined at the 20th day. In the presence of CLN, however, the fibrils are much shorter and less dense. Addition of CLN as late as the 17th day can still dissolves the preformed fibrils. These observations were compared to the effect of CLN on the neurotoxic activity of beta-amyloid peptides in the cell culture model (SHSY-5Y). The beta-amyloid peptides were pre-incubated with CLN at various times and used to treat SHSY-5Y neuroblastoma cells for up to 4 days. The cytotoxic effect was monitored by trypan blue exclusion. We demonstrated that 24-48 h treatment was the onset of toxicity of 10-50 microM of beta-amyloid peptides. Pre-incubation of 0.0025-0.25muM of CLN with 25 microM of beta-amyloid peptides leads to near-complete abolition of cytotoxicity. Low doses of CLN (2.5 nM) can attain cytotoxic protection levels similar to those of highest doses (0.25 microM). Thus, the time course for the appearance of beta-amyloid fibrils coincides with that for cytotoxicity, and that the reduction of fibrils of beta-amyloid peptides by CLN is concomitant with the reduction of the cytotoxic effects of beta-amyloid on SHSY-5Y neuroblastoma cells. Our studies suggest that the neuroprotective effects exerted by CLN are related to the reduction of beta-amyloid fibrils.
Schuster
David
D
Department of Cancer Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
Rajendran
Anitha
A
Hui
Sek Wen
SW
Nicotera
Thomas
T
Srikrishnan
Thamarapu
T
Kruzel
Marian L
ML
D000544:Alzheimer Disease / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D000686:Amyloidosis / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D010455:Peptides / Q000494:pharmacology*; D017433:Protein Structure, Secondary / Q000187:drug effects
D016229:Amyloid beta-Peptides; D036341:Intercellular Signaling Peptides and Proteins; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D010455:Peptides; C078592:amyloid beta-protein (1-40); C105874:colostrinine