Role of SIRT1 and Progesterone Resistance in Normal and Abnormal Endometrium

Abstract

Context Progesterone resistance, a known pathologic condition associated with a reduced cellular response to progesterone and heightened estrogen responses, appears to have a normal physiologic role in mammalian reproduction. The molecular mechanism responsible for progesterone resistance in normal and abnormal endometrium remains unclear. Objective To examine the roles of Sirtuin-1 (SIRT1) in normal endometrium as well as endometrium associated with infertility and endometriosis, as an epigenetic modulator associated with progesterone resistance. Methods SIRT1 expression was examined by Western blot, RT-qPCR and immunohistochemistry in mouse uterus and human endometrium. Mice with uterine specific Sirt1 overexpression were developed to examine SIRT1’s role in endometrial function and endometriosis development. EX-527, a SIRT1 inhibitor, and SRT1720, a SIRT1 agonist, were also used to evaluate SIRT1 effect on endometriosis. Results In normal healthy women, endometrial SIRT1 is expressed only during menses. SIRT1 was dramatically overexpressed in the endometrium from women with endometriosis in both the epithelium and strom. In mice, SIRT1 is expressed at the time of implantation between day 4.5 and 5.5 of pregnancy. Overexpression of SIRT1 (Sirt1 ^over) in the mouse uterus leads to subfertility due to implantation failure and decidualization defects and progesterone resistance. SIRT1 overexpression in endometriotic lesion promotes worsening endometriosis development. EX-527 (SIRT1 inhibitor) significantly reduced the number of endometriotic lesions in the mouse endometriosis model. Conclusions SIRT1 expression and progesterone resistance appears to play -roles in normal endometrial functions. Aberrant SIRT1 expression contributes to progesterone resistance and may participate in the pathophysiology of endometriosis. SIRT1 is a novel and targetable protein for the diagnosis as well as treatment of endometriosis and the associated infertility seen in this disease.