Endometrial Expression of Estrogen Receptors and the Androgen Receptor in Women With Polycystic Ovary Syndrome: A Lifestyle Intervention Study

CONTEXT

Polycystic ovary syndrome (PCOS) is a common cause of anovulation. It may also negatively affect the endometrium, which could lead to implantation failure and proliferative aberrations.

OBJECTIVE

Our objective was to study sex hormone receptors in the endometrium of women with PCOS.

DESIGN

This is a cross-sectional study and lifestyle intervention.

SETTING

Clinical and laboratory research unit was undertaken at a university hospital.

PARTICIPANTS

Twenty overweight/obese women fulfilling all three PCOS criteria (anovulation, hyperandrogenism, and polycystic ovaries), 10 body mass index-matched regularly menstruating controls, 11 normal-weight women with PCOS, and 11 normal-weight controls.

INTERVENTION

Intervention for this study included dietary management and physical exercise.

MAIN OUTCOME MEASURES

mRNA levels and immunostaining of estrogen receptor α (ERα) and β (ERβ), nongenomic estrogen receptor α36 (ERα36), and G-protein-coupled estrogen receptor-1 (GPER), and the androgen receptor (AR) on cycle days 6-8 and cycle days 21-23.

RESULTS

Before intervention, mRNA levels of ERα, ERα36, and the ERα/ERβ mRNA ratio were lower in proliferative endometrium of overweight/obese PCOS women compared with controls (P < .05). After intervention, ERα protein and the ERα/ERβ protein ratio in proliferative endometrium increased and were higher in PCOS women with improved menstrual function than in those without improvement (P < .05). In the subgroup of PCOS women with restored ovulation, only higher protein levels of GPER were found in secretory endometrium (P < .01). However, PCOS women who remained anovulatory had higher protein levels of ERα, GPER, and AR on cycle days 21-23 than controls (P < .05).

CONCLUSIONS

Lifestyle intervention alters, but does not fully restore, ER and AR expression in proliferative and secretory endometrium of obese women with PCOS.

Lifestyle intervention up-regulates gene and protein levels of molecules involved in insulin signaling in the endometrium of overweight/obese women with polycystic ovary syndrome

STUDY QUESTION

Does lifestyle intervention aiming at weight loss influence endometrial insulin signaling in overweight/obese women with polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Lifestyle intervention up-regulates, both at the mRNA and protein levels, components of insulin signaling in the endometrium of overweight/obese PCOS women, in relation to an improved menstrual pattern.

WHAT IS KNOWN ALREADY

PCOS is a multifactorial endocrine disorder diagnosed by two of the following three criteria: chronic anovulation, hyperandrogenism and polycystic ovaries. Many women with PCOS also have insulin resistance and obesity. The syndrome is furthermore associated with endometrial cancer and possible alterations in endometrial function and receptivity.

STUDY DESIGN, SIZE, DURATION

This study assessed the effects of a combined diet and exercise lifestyle intervention for 3 months.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A group of 20 overweight/obese PCOS women with anovulation, hyperandrogenism and polycystic ovaries were subjected to a combined diet and exercise program for 3 months. Ten body mass index (BMI)-matched regularly menstruating overweight/obese controls, nine normal-weight PCOS women and ten normal-weight controls were also included in the study. In an academic clinical setting, women were examined in mid-follicular phase for endocrine assessment and determination of endometrial levels of mRNA and immunohistochemical staining of insulin signaling molecules (the insulin receptor, insulin receptor substrate-1 (IRS1) and glucose transporter (GLUT) 1 and 4).

MAIN RESULTS AND THE ROLE OF CHANCE

Women with PCOS exhibited lower levels of IRS1 (P < 0.01) and GLUT4 (P < 0.01) mRNA in their proliferative endometrium than BMI-matched controls. After lifestyle intervention, weight loss averaged 4.7% and the menstrual pattern improved in 65% of the overweight/obese women with PCOS. Levels of IRS1 (P < 0.01) and GLUT1 (P < 0.05) mRNA were significantly up-regulated in the endometrium of those women with improved menstrual function, as were the protein expression levels of pY612IRS1 (the activated IRS1 form, P < 0.05), pS312IRS1 (the inhibitory form of IRS1, P < 0.05) and GLUT1 (P < 0.05). Improvement in the menstrual function of women in the obese/overweight group following the lifestyle intervention was positively correlated with the increase in the endometrial level of IRS1 mRNA (r = 0.63, P < 0.01) and negatively correlated with the change in BMI (r = -0.50, P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

The number of women in each group was limited, although the power calculation indicated that the number of patients subjected to the lifestyle intervention was sufficient.

WIDER IMPLICATIONS OF THE FINDINGS

We propose that up-regulation of endometrial IRS1 and GLUT1 in overweight/obese women with PCOS following lifestyle intervention improves the glucose homeostasis and thereby restores the functioning of the endometrium in these women.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported financially by the Swedish Research Council (A.L.H., 20324), Karolinska Institutet and the Stockholm County Council. None of the authors has any conflict of interest to declare.