Abstract 1868: Glycodelin-producing endometrial adenocarcinoma cells are resistant to TGFβ

Abstract Glycodelin is a secreted glycoprotein belonging to lipocalin protein family. It is expressed mainly in reproductive and glandular tissues. Glycodlin is involved in the regulation of reproductive and immune systems and it drives epithelial differentiation. In endometrium, the expression of glycodelin is abundant in secretory phase of the menstrual cycle, while in proliferative phase it is not expressed. Most studies agree that glycodelin is not expressed in endometrial cancer. To study the effects of glycodelin in endometrial cancer cells, we have made stable glycodelin-producing HEC-1B endometrial adenocarcinoma cells. Previously, we have shown that glycodelin differentiated HEC-1B cells towards less malignant phenotype and the cells formed significantly smaller tumors in preclinical xenograft mice. In addition, glycodelin-producing cells were resistant to phorbol ester-stimulated migration and phenotypic differentiation, which was mediated by repressed activation of PKCδ. Here we studied the effect of TGFβ on glycodelin-induced differentiation of the HEC-1B cells. Glycodelin-producing and control cells were plated on Matrigel and grown with or without TGFβ. The media was changed every second day and the cells were monitored up to one week. For Western blot analysis the cells were grown on Matrigel and TGFβ was added for 0-2h, after which the cells were detached from Matrigel and lysed. TGFβ induced control cells to form net-like structures, similar to those found after phorbol ester exposure. However, the glycodelin-producing cells remained unresponsive. PKCδ siRNA and PKCδ inhibitor Rottlerin inhibited the effects of TGFβ. Western blot analysis showed equal phosphorylation levels of SMAD2 in glycodelin-transfected and control cells. In contrast, PKCδ and ERK1/2 were differently phosphorylated, indicating the involvement of MAPK-pathway in the TGFβ-induced changes of the control cells. Endometrial cancer is the most common cancer of the female reproductive tract in developed countries. However, the molecular mechanisms affecting the pathogenesis of the disease are still poorly understood. It has been suggested that TGFβ is involved in carcinogenesis of endometrial cancer. Therefore, our results showing that glycodelin-producing HEC-1B endometrial adenocarcinoma cells are resistant to the effects of TGFβ, due to the repressed PKCδ phosphorylation, may be important to understand the pathogenic mechanisms of endometrial cancer. Citation Format: Laura Hautala, Hannu Koistinen. Glycodelin-producing endometrial adenocarcinoma cells are resistant to TGFβ. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1868.