Media from rhabdomyosarcoma and neuroblastoma cell cultures stimulate in vitro aggregation and fibrillization of amyloid beta-protein

In vitro aggregation and fibrillization of synthetic amyloid beta-protein A beta 1-40 was assessed in the conditioned media from rhabdomyosarcoma (CRL 1598, HTB 82, HTB 153, CCL 136), adenocarcinoma (CCL 218), neuroblastoma (SY5Y), and COS cells cultured in the absence and presence of 10% heat-inactivated fetal bovine serum (FBS). The aggregation and formation of cross beta-pleated sheet structures in A beta was quantitated by Thioflavin T (ThT) fluorescence spectroscopy, while the morphology of A beta fibrils was examined in negative staining in the electronmicroscope (EM). In cultures supplemented with 10% FBS, the conditioned media from CRL 1598, HTB 82, CCL 218, and SY5Y cell cultures stimulated 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 equal to HTB 82 > CCL 218, and the stimulation was higher in 2 week cultures than in 1 week cultures. Similar studies using media from HTB 153, CCL 136 and COS cell cultures showed no effect on A beta 1-40 aggregation. In serum-free cell cultures, only media from SY5Y and CRL 1598 could promote significant aggregation of A beta 1-40. Negative staining 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 CRL 1598 rhabdomyosarcoma cell line may serve as experimental models for in vitro studies of extracellular aggregation and fibrillization of A beta-protein in cell cultures, while rhabdomyosarcoma HTB 82 and adenocarcinoma CCL 218 may be models for study of A beta aggregation only.