Endometriotic cells are resistant to interferon-γ-induced cell growth inhibition and apoptosis: a possible mechanism involved in the pathogenesis of endometriosis

Abstract

In order to evaluate the involvement of cell proliferation and apoptosis in the pathogenesis of endometriosis, we investigated the effects of interferon-gamma (IFN-gamma) on cell growth inhibition and apoptosis of cultured ovarian endometriotic cyst stromal cells (ECSC), eutopic endometrial stromal cells with endometriosis (ESCwE) and normal endometrial stromal cells (NESC) by modified methylthiazoletetrazolium assay, 5-bromo-2'-deoxyuridine incorporation assay and internucleosomal DNA fragmentation assay. The expression of apoptosis-related molecules and IFN-gamma receptor 1 was also examined in ECSC, ESCwE and NESC using western blot analysis. IFN-gamma significantly inhibited cell proliferation and DNA synthesis of ESCwE and NESC, and induced apoptosis of these cells. In contrast, IFN-gamma did not show apparent effects on the viable cell number, DNA synthesis, or apoptosis of ECSC. An up-regulated expression of Bcl-2 and Bcl-X(L) proteins was observed in ECSC in comparison with ESCwE and NESC, whereas the levels of Bax, Bad, Fas and Fas ligand proteins in ECSC were similar to those in ESCwE and NESC. IFN-gamma receptor 1 expression was detected in ECSC, ESCwE and NESC. Enhanced expression of anti-apoptotic molecules in the ectopic endometrial cells may contribute to the development of endometriosis by conferring resistance to cytokine-induced apoptosis and increasing the chance that these cells will survive and implant outside the uterus. Further investigations on the regulation of cell proliferation in both the endometriotic and the normal endometrium may be important for the elucidation of the pathogenesis of endometriosis.

Application of the nuclear factor-κB inhibitor BAY 11-7085 for the treatment of endometriosis: an in vitro study

“…We have demonstrated that endometriotic cells, but not normal endometrial cells, are resistant to cytokine-induced apoptosis (20). It has also been demonstrated that endometrial apoptosis in the eutopic endometrium is lower in women with endometriosis than controls and is further decreased in the ectopic endometrium (8,10).…”

“…Internucleosomal DNA fragmentation in ECSCs after BAY 11-7085 treatment was evaluated using a Quick Apoptotic DNA Ladder Detection Kit (BioVision Research Products, Mountain View, CA), as previously described (20). Cells (1 ϫ 10 7 ) of ECSCs were plated onto 100-mm culture dishes (Corning) in 10 ml of DMEM supplemented with 10% heat-inactivated FBS and cultured overnight.…”

“…The BAY 11-7085-induced apoptosis of ECSCs and NESCs was quantified by direct determination of nucleosomal DNA fragmentation by Cell Death Detection ELISA (Roche) as previously described (20). The assay used specific monoclonal antibodies directed against histones from fragmented DNA, allowing the determination of mono-and oligonucleosomes in the cytoplasmic fraction of cell lysates.…”

“…It has also been demonstrated that endometrial apoptosis in the eutopic endometrium is lower in women with endometriosis than controls and is further decreased in the ectopic endometrium (8,10). Both the inability of endometriotic cells to transmit a "death" signal and the ability of the cells to avoid cell death have been associated with increased expression of anti-apoptotic factors [e.g., B-cell lymphoma/leukemia-2 (Bcl-2) and Bcl-X L ] and the decreased expression of preapoptotic factors (e.g., Bax) (15,20). These findings encouraged the present authors to evaluate apoptosis-inducing agents for the treatment of endometriosis.…”

“…Our laboratory and others have focused on molecular strategies to alter the antiapoptotic response of endometriotic cells to both novel and traditional therapeutic agents (18,20). In the present study, we evaluated the effects of BAY 11-7085, an inhibitor of I B phosphorylation and activator of JNK and p38 MAPK, on the proliferation, cell cycle, and apoptosis of cultured endometriotic cells, using methods that were previously proposed for evaluating novel therapeutic agents for endometriosis (18,20). We also discuss new therapeutic strategies for the treatment of endometriosis.…”