Circulating levels and subcutaneous adipose tissue gene expression of pigment epithelium-derived factor in polycystic ovary syndrome and normal women: a case control study

BACKGROUND Polycystic ovary syndrome (PCOS) has been recognized as a metabolic disorder, manifested by abdominal obesity, insulin resistance, dyslipidemia and hypertension. Pigment epithelium-derived factor (PEDF), a member of the serine protease inhibitor family, is a pleiotropic protein known for its antiangiogenic, antioxidant, and neuroprotective properties and has been shown to induce insulin resistance and play a role in glucose metabolism. Recent studies investigating circulating PEDF levels show elevated serum PEDF in association with insulin resistance in normal-weight women with PCOS, but not in obese PCOS patients. The aims of this study were 1) to assess PEDF gene expression in subcutaneous adipose tissue (scAT) from women with PCOS and nonhirsute, ovulatory controls, and 2) to determine the circulating levels of PEDF in these groups. METHODS Total RNA was extracted from adipose tissue biopsy samples and reverse-transcribed to cDNA. Real-time quantitative PCR was performed to determine relative gene expression levels. RESULTS The 22 women with PCOS and 14 non-PCOS controls included in the study had similar age, BMI, and fasting glucose, triglycerides, and HDL-cholesterol levels. Participants with PCOS exhibited higher 2 h oral glucose tolerance test levels (p = 0.006), total (p = 0.026) and LDL-cholesterol (p = 0.036), Ferriman-Gallwey score (p = 0.003) and total testosterone (p = 0.001) as compared to controls. BMI-adjusted PEDF serum levels and scAT gene expression were similar in the PCOS and control groups (p = 0.622 and p = 0.509, respectively). Circulating PEDF levels were not associated with scAT PEDF gene expression. Multiple regression analysis revealed that, in women with PCOS, insulin contributed positively and significantly to serum PEDF (p = 0.027), independently of testosterone. CONCLUSION Serum PEDF levels and scAT gene expression were associated with metabolic risk factors, but did not differ between women with PCOS and age- and BMI-matched controls. Circulating levels and scAT gene expression of PEDF were not associated in the study subjects, suggesting additional sources for PEDF in addition to or instead of fat tissue.