The effect of overweight and obesity on proliferation and activation of AKT and ERK in human endometria.

OBJECTIVE

To examine whether overweight and obesity could lead to increased endometrial proliferation and activation of AKT and ERK1,2 in cycling premenopausal women.

METHODS

Endometrial and blood samples were obtained from women with normal endometrial histology, and allocated into three groups-normal-weight, overweight and obese-according to the subject's body mass index (BMI). Samples from obese patients with type-I endometrial cancer (EC) were included as a control. Cell proliferation was measured by immunohistochemical detection of Ki67 and phosphorylated histone H3 (p-H3). AKT and ERK1,2 activation was assessed by Western blot. Circulating steroids, leptin and insulin were measured by immunoassays.

RESULTS

In endometrial samples with normal histology, epithelial cell proliferation was higher in the overweight and obese groups versus the normal-weight set (P<0.05). Proliferation indexes were positively correlated with the subject's BMI and serum levels of estrogen, leptin and insulin (P<0.05). Increased phosphorylated AKT (pAKT) (1.6-fold) and ERK1,2 (pERK1,2) (8.7-fold) were observed in endometria from obese with respect to normal-weight subjects (P<0.05). Similarly, increased phosphorylation of AKT (0.7-fold) and ERK1,2 (2.3-fold) was detected in endometria from overweight as compared with the normal-weight group (P<0.05). In women with EC, we found a significant increase in endometrial proliferation, and in pAKT and pERK1,2 expression levels when compared to patients with normal endometrial histology.

CONCLUSION

These results show correlation between obesity (and overweight) and increased endometrial cell proliferation, and the activation of AKT and ERK1,2. These features could be related with the higher risk to develop type-I EC in overweight and obese women.