Interleukin-6 increases the expression of key proteins associated with steroidogenesis in human NCI-H295R adrenocortical cells

- Interleukin 6 (IL-6) increased H295R adrenocortical cell cortisol release.
- IL-6 increased expression of H295R StAR and five steroidogenic enzymes (SE).
- IL-6 increased H295R SF-1, a nuclear factor that increases SE and StAR expression.
- IL-6 decreased expression of H295R DAX-1, a nuclear factor that inhibits SE and StAR.
- JAK/STAT phosphorylation increased by IL-6; JAK/STAT inhibition decreased StAR.

Mechanisms of interleukin-6 (IL-6)-induced cortisol release (CR) were investigated by exposing H295R cells to IL-6 and determining mRNA/protein expression (PCR/western blots) for steroidogenic enzymes (SE), steroidogenic acute regulatory protein (StAR), steroidogenic factor-1 (SF-1) (enhances SE/StAR expression), activator protein 1 (AP-1) (regulates SE/StAR expression) and adrenal hypoplasia congenita-like protein (DAX-1) (inhibits SE/StAR expression). Promoter activity of StAR (SPA) was measured by a luciferase-coupled promoter. Cortisol release was increased by 10 ng/mL IL-6 (24 h P < 0.01). Proteins/mRNAs (StAR, cholesterol side chain cleavage enzyme, SF-1, AP-1) and SPA were increased by IL-6 (60 min 1-50 ng/mL IL-6; 5 ng/mL IL-6 30-120 min P < 0.05). Four other SE proteins/mRNAs were also increased by 10 ng/mL IL-6 (60 min P < 0.01). Protein/mRNA for DAX-1 was decreased by IL-6 (60 min 1-50 ng/mL IL-6; 5 ng/mL IL-6 30-120 min P < 0.01). Phosphorylation of Janus kinase (JAK) and signal transducer and activator of transcription (STAT) was increased by IL-6 (JAK2 60 min 1-50 ng/mL IL-6; 10 ng/mL IL-6 5-60 min P < 0.05; STAT1 and STAT3 60 min 10 ng/mL IL-6 P < 0.01). Inhibition of JAK/STAT with AG490 (10 μM) or piceatannol (50 μM) blocked (P < 0.01 10 ng/mL IL-6 vs. IL-6 plus AG490 or piceatannol) IL-6-induced increases in SPA and StAR mRNA. In summary, IL-6-induced CR may be facilitated by increased StAR and SE mediated by increased SF-1 and AP-1, decreased DAX-1, and increased phosphorylation of JAK/STAT.