MEDIA FROM RHABDOMYOSARCOMA AND NEUROBLASTOMA CELL-CULTURES STIMULATEIN-VITRO AGGREGATION AND FIBRILLIZATION OF AMYLOID BETA-PROTEIN

In vitro aggregation and fibrillization of synthetic amyloid beta-prot ein A beta 1-40 was assessed in the conditioned media from rhabdomyosa rcoma (CRL 1598, HTB 82, HTB 153, CCL 136), adenocarcinoma (CCL 218), neuroblastoma (SY5Y), and COS cells cultured in the absence and presen ce of 10% heat-inactivated fetal bovine serum (FBS). The aggregation a nd formation of cross beta-pleated sheet structures in A beta was quan titated by Thioflavin T (ThT) fluorescence spectroscopy, while the mor phology of A beta fibrils was examined in negative staining in the ele ctronmicroscope (EM). In cultures supplemented with 10% FBS, the condi tioned media from CRL 1598, HTB 82, CCL 218, and SY5Y cell cultures st imulated A beta aggregation in a time-dependent manner as compared to that of control (serum-containing medium that had not been exposed to cells). The order of stimulation was SY5Y > CRL 1598 greater than or e qual to HTB 82 > CCL 218, and the stimulation was higher in 2 week cul tures than in 1 week cultures. Similar studies using media from HTB 15 3, CCL 136 and COS cell cultures showed no effect on A beta 1-40 aggre gation. In serum-free cell cultures, only media from SY5Y and CRL 1598 could promote significant aggregation of A beta 1-40. Negative staini ng in EM revealed A beta fibril formation only with conditioned media from SY5Y and CRL 1598 cultured under serum free conditions; no A beta fibrils were noticed in media from cell cultures supplemented with 10 % FBS. We propose that both the SY5Y neuroblastoma cell line and the C RL 1598 rhabdomyosarcoma cell line may serve as experimental models fo r in vitro studies of extracellular aggregation and fibrillization of A beta-protein in cell cultures, while rhabdomyosarcoma HTB 82 and ade nocarcinoma CCL 218 may be models for study of A beta aggregation only .