Myo-Inositol and D-Chiro-Inositol Reduce DHT-Stimulated Changes in the Steroidogenic Activity of Adult Granulosa Cell Tumors

Considering the properties of myo-inositol (MI) and D-chiro-inositol (DCI), which are well known in polycystic ovary syndrome therapy, and the limitations of adult granulosa cell tumor (AGCT) treatment, especially for androgen-secreting tumors, we studied the role of MI and DCI in the androgen-rich environment of AGCTs. For this purpose, we analyzed the mRNA expression of steroidogenic genes and the secretion of progesterone (P4) and 17β-estradiol (E2) in an unstimulated and/or dihydrotestosterone (DHT)-stimulated environment under MI and DCI influence. Thus, we used the HGrC1 and KGN cell lines as in vitro models of healthy and cancerous granulosa cells. We found that DHT, the most potent androgen, increased E2 secretion and steroidogenic acute regulatory protein (<i>StAR</i>) and cytochrome P450 side-chain cleavage gene (<i>CYP11A1</i>) mRNA expression without affecting 450 aromatase (<i>CYP19A1</i>) in AGCTs. However, after the MI and DCI treatment of KGN cells, both compounds strongly reduced <i>StAR</i> and <i>CYP11A1</i> expression. Interestingly, in DHT-stimulated KGN cells, only DCI alone and its cotreatment with MI reduced both <i>CYP11A1</i> mRNA and E2 secretion. These findings suggest that <i>CYP11A1</i> is responsible for the antiestrogenic effect of DCI in the androgen-rich environment of AGCTs. Therefore, MI and DCI could be used as effective agents in the adjuvant treatment of AGCT, but further detailed studies are needed.