We have earlier shown that
cobalt chloride (CoCl2)-induced
hypoxia and second messenger
8-bromoadenosine 3', 5'-cyclic
adenosine monophosphate (8-Br-cAMP) stimulates
vascular endothelial growth factor (
VEGF) production in Leydig
tumor cell derived MA-10 cells. Both stimuli follow common signal transduction pathways including
protein kinase A (PK-A), extracellular regulated
kinase 1/2 (ERK1/2), and phosphatidyl inositol-3
kinase/akt (PI3-K/Akt) pathways in the stimulation of
VEGF by MA-10 cells. In the present study we investigated the role of CoCl2 and 8-Br-cAMP on
steroid production in MA-10 cells. The MA-10 cells were cultured in Waymouth MB 752/1 medium, supplemented with 15% heat inactivated horse serum.
Progesterone was estimated by radioimmunoassay (RIA).We report that 8-Br-cAMP stimulated
progesterone production by the MA-10 cells whereas CoCl2 inhibited the same. Also, 8-Br-cAMP stimulated
steroidogenic acute regulatory protein (StAR) and
cytochrome P450 side-chain cleavage
enzyme (P450scc) mRNAs expression. However, CoCl2 had no effect on StAR
mRNA.
Cobalt chloride directly inhibited the expression of P450scc
mRNA. The decrease in
progesterone production could be attributed to three different mechanisms, (1) an increase in production of
reactive oxygen species (ROS), (2) an increase in HIF-1α activity, and (3) ultimately a decrease in the level of
cytochrome P450 side chain cleavage (CYT P450scc).
Hypoxia has an action and mechanism of action similar to that of
gonadotropins on
VEGF production, whereas they have a contrasting effect on steroidogenesis. This study suggests that
hypoxia could be as important as
gonadotropins in regulating Leydig cell steroidogenesis.