title: Effects of cell density and conditioned medium on alpha 2A adrenergic receptor density and messenger RNA abundance in HT-29 cells.
abstract: We have examined the relationship between cell density and alpha 2A adrenergic receptor number and mRNA in HT-29 cells. alpha 2A receptors increased with increasing cell density from 75 +/- 25 to 400 +/- 73 fmol/mg protein; alpha 2A receptor mRNA also increased about 4 fold with no change in abundance of beta-actin mRNA. We prepared serum-free conditioned medium (SFCM) from confluent dishes of HT-29 cells and applied this SFCM to cells seeded at low density. A 4.7-fold increase in receptor number was observed in HT-29 cells cultured in SFCM for 3 days and alpha 2A receptor mRNA level increased about 3-fold after 24 h. Dialysis of SFCM against fresh growth medium did not abolish these effects. These results suggest that a substance secreted from HT-29 cells regulates expression of alpha 2A receptors.
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Palo Alto, California.
authors.forename: M
authors.initials: M
authors.lastname: Sakaue
authors.forename: B B
authors.initials: BB
authors.lastname: Hoffman
mesh_terms: D002452:Cell Count; D003110:Colonic Neoplasms / Q000737:chemistry; D017077:Culture Media, Conditioned; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis*; D018341:Receptors, Adrenergic, alpha-2 / Q000032:analysis* / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D017077:Culture Media, Conditioned; D012333:RNA, Messenger; D018341:Receptors, Adrenergic, alpha-2