title: Porcine smooth muscle cell-conditioned medium stimulates LDL receptor activity in Hep G2 cells.
abstract: Paracrine factors may modulate low density lipoprotein (LDL) receptor activity in hepatocytes. To study this the effect of conditioned medium prepared from a range of cell types on the binding and internalisation of 125I-LDL in Hep G2 cells was studied. Seven of the fourteen conditioned media tested, including those from P388D1, U937, porcine smooth muscle (Pc SMC) Swiss 3T3, STO, = 48 and MDCK cells, were found to increase the binding and internalisation of 125I-LDL at 37 degrees C by Hep G2 cells (P < 0.01). The largest increase in LDL receptor activity was produced by conditioned medium from Pc SMC cells and was, therefore, selected for further analysis. The Pc SMC-conditioned medium increased LDL receptor number in Hep G2 cells by three-fold but had no effect on LDL receptor activity in human skin fibroblasts. DNA synthesis and cholesterol synthesis by Hep G2 cells were inhibited by Pc SMC-conditioned medium. Preliminary characterisation of the Pc SMC-derived factor(s) suggests that it is a protein(s) of low relative molecular mass.
authors: Department of Pathology, Cambridge University, UK.
authors: C D
authors: CD
authors: Moorby
authors: E
authors: E
authors: Gherardi
authors: D
authors: D
authors: Riddell
authors: D E
authors: DE
authors: Bowyer
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002784:Cholesterol / Q000096:biosynthesis; D017077:Culture Media, Conditioned; D006801:Humans; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism*; D013552:Swine; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: D017077:Culture Media, Conditioned; D011973:Receptors, LDL; D016212:Transforming Growth Factor beta; D002784:Cholesterol