STAT3 activation by IL-6 from adipose-derived stem cells promotes endometrial carcinoma proliferation and metastasis

Endometrial cancer is the most common gynaecological cancer, and its incidence is increasing. Obesity is a well-recognized risk factor for endometrial cancer, and the mechanisms by which adipose tissue influences tumour development remain controversial. In this study, we examined the high IL-6 level in the ADSCs supernatant following treatment of endometrial cancer cell CM. Then, the activation of STAT3, a major tumourigenic IL-6 effector, was examined in ADSCs CM treated endometrial cancer cells. Conditioned ADSC medium was used to stimulate endometrial cancer cell growth in vitro. Similar to IL-6, ADSC-conditioned medium significantly promoted endometrial cancer growth and invasion. Furthermore, siRNA-mediated STAT3 inhibition in endometrial cancer cells decreased the ADSC-mediated promotion of cell proliferation and invasion. In addition, a subcutaneous nude mouse model of endometrial cancer was established to monitor the tumour-promoting effect of ADSCs. ADSC-conditioned medium promoted tumour growth, and STAT3 inhibition attenuated this effect. Based on these data, ADSCs promote endometrial cancer progression by the STAT3 signalling pathway.