[Detection and significance of phosphatidylinositol 3-kinase in adipose tissue of polycystic ovary syndrome patients with insulin resistance]

Abstract

Objective: To investigate the expression of phosphatidylinositol 3-kinase (PI-3K) in adipose tissue of polycystic ovary syndrome patients (PCOS), and explore molecular mechanisms of insulin resistance (IR) in PCOS.

Methods: Samples from patients with PCOS with IR (n = 19), PCOS without IR (n = 10) and controls (n = 15) were collected. Serum fasting insulin (FIN) and fasting plasma glucose (FPG) were measured. Insulin resistance index was calculated using homeostasis model assessment (HOMA) to analyze the relationship between these markers and IR. Western blot technique was used to detect the PI-3K p85 subunit. Gene expression of PI-3K p85 subunit was detected by reverse transcription polymerase chain reaction (RT-PCR) method. Kinase activity was detected by immunoprecipitation, thin-layer chromatography and gamma scintillation counting.

Results: (1) The levels of FIN [(25.2 +/- 3.8) mU/L] and HOMA-IR (1.6 +/- 0.3) in PCOS with IR were significantly higher than those in PCOS without IR [(13.4 +/- 3.8) mU/L, 0.9 +/- 0.3] and controls [(9.5 +/- 2.6) mU/L, 0.5 +/- 0.3; all P < 0.05). (2) There was no significant difference in the protein (0.65 +/- 0.10) and gene expression (0.92 +/- 0.12) of PI-3K p85 subunit in PCOS with IR compared with PCOS without IR (0.72 +/- 0.10, 1.01 +/- 0.10) and control groups (0.73 +/- 0.14, 1.00 +/- 0.12; P > 0.05). (3) PI-3K activity in PCOS with IR (81%) and PCOS without IR (89%) was significantly decreased (P < 0.01, P < 0.05) and negatively correlated with HOMA-IR (r = -0.69, P < 0.01; r = -0.62, P < 0.05).

Conclusions: No significant difference in the protein and gene expression of PI-3K p85 subunit in PCOS with IR is found. The decreased PI-3K activity may lead to IR of PCOS.