Objective: To determine if luteinizing human granulosa cells contain messenger ribonucleic acid (mRNAs) encoding insulin-like growth factor-binding protein (IGFBPs) and if cultured granulosa secrete IGFBPs into conditioned medium (CM).
Design: Northern analysis, using IGFBP-specific complementary deoxyribonucleic acid probes, was used to detect granulosa-derived IGFBP mRNAs. Western ligand blot analysis of CM was used to detect IGFBPs secreted by granulosa cultures with and without human chorionic gonadotropin (hCG).
Setting: Granulosa cells were obtained from the In Vitro Fertilization (IVF) Program at Stanford University, a private teaching institution.
Patients, participants: Patients undergoing IVF for tubal disease.
Interventions: None.
Main outcome measures: Transcripts of IGFBP mRNA and IGFBPs secreted into CM were detected by autoradiography of Northern and Western ligand blots, respectively.
Results: Transcripts of IGFBP-3, IGFBP-2, and IGFBP-1 mRNA were detected in human luteinizing granulosa. Cultured granulosa secreted IGFBPs with molecular weights corresponding to IGFBP-3, IGFBP-2, and IGFBP-1, and the latter two IGFBPs increased with 10 ng/mL hCG. A 24 kd IGFBP was noted, which may be newly characterized IGFBP-4.
Conclusions: These data show that luteinizing human granulosa cells express mRNAs encoding three IGFBPs, secrete IGFBPs into culture medium, and that production of at least two of the IGFBPs is hCG-dependent, further supporting a role for the IGF system in human folliculogenesis.