Partial characterization of a unique growth factor secreted by XXXX Sertoli cells.

@entity1 @entity851 @entity19 @entity957 @entity1014 @entity35
@entity1 Sertoli cells were grown in a serum-free environment, and the Sertoli cell conditioned medium (hSCCM) was tested for mitogenic activity. The presence of a potent growth factor(s), termed @entity851 ( @entity851 ), in hSCCM was confirmed and supports previous observations based on experiments using @entity35 SCCM. Mitogenicity of hSCSGF was demonstrated in cell proliferation assays with the A431 ( @entity1 @entity957 ) cell line and in [methyl-3H]-thymidine incorporation (DNA synthesis) assays with the @entity19 ( @entity19 embryo fibroblast) cell line. In a dose-dependent manner, hSCSGF stimulated A431 cell growth up to 4-fold over control values (P less than 0.0001) and stimulated @entity1014 incorporation up to 4.5-fold over control values (P less than 0.0002). Importantly, @entity851 stimulated A431 proliferation 2-fold over control values (P less than 0.0002) in the presence of 5% serum. With the exception of @entity35 @entity851 , @entity1 @entity851 is the only growth factor known to stimulate A431 cells. @entity851 also demonstrated epidermal growth factor (EGF)-like activity based upon displacement of EGF from its receptor in a radioreceptor assay. However, @entity851 is not EGF since it is a potent stimulator of A431 cells, whereas EGF is inhibitory. The growth factor was stable to heat, freeze-thaw, acid (pH 3), and trypsin treatment. Furthermore, it did not bind heparin agarose and is thus distinct from the endothelial cell growth factor family. High-pressure liquid chromatography on size exclusion (TSK G2000 SW) columns revealed an approximate size of 8000 daltons. @entity1 @entity851 is a unique growth factor and may play a key role in the regulation of normal spermatogenesis.
