Search

Background The therapy concepts that target several members of krüppel like factor (KLF) family have been achieved in breast cancer (BC). However, the role of KLF11 in BC remains unclear. This study explored the prognostic significance of KLF11 in BC patients and investigated its functional roles in this malignancy. Methods Immunohistochemistry (IHC) staining of KLF11 in 298 patients’ samples was performed to determine the prognostic role of the KLF11. Then the protein level was correlated to clinicopathological characteristics and survival outcomes. Afterward, the function of KLF11 was explored in vitro with siRNA-mediated loss-of-function of cell viability, proliferation, and apoptosis. Results From the cohort study, we found that the expression of KLF11 was positively associated with highly proliferative BC of BC. Furthermore, prognostic analysis demonstrated that KLF11 was an independent negative factor for disease-free survival (DFS) and distant-metastasis-free survival (DMFS) of BC. The KLF11-related prognostic model for DFS and DMFS showed high accuracy in predicting the 3-,5- and 10 -year survival probability of BC patients. Additionally, the knockdown of KLF11 inhibited cell viability and proliferation, as well as induced cell apoptosis in MCF7 and MDA-MB-231 cells, while only inhibited cell viability and induced cell apoptosis in SK-BR-3 cells. Conclusions Our study indicated that targeting KLF11 is an interesting therapeutic concept and further research could lead to a new therapeutic improvement in BC, especially in highly aggressive molecular subtypes.

BackgroundBreast cancer (BC) is a heterogeneous disease characterized by distinct molecular subtypes. Krüppel like Factor (KLF) family members in BC have been widely studied. However, the roles of KLFs as tumor-promoters or tumor-suppressors are context-dependent. KLF11, as a member of this family, the expression pattern and prognostic relevance of which in BC remains unclear.Methods To clarify whether KLF11 acts as a tumor-promoter or a tumor-suppressor in BC, we explored the prognostic role of the KLF11 in BC patients by performing immunohistochemistry (IHC) staining of KLF11 in 298 patients samples. Then we correlated the expression to clinicopathological characteristics and survival outcomes. To investigate the function of KLF11 in tumor cells, we performed different assays of cell viability, cell proliferation, and cell apoptosis assays in three distinct molecular subtypes of BC cell lines with siRNA-mediated loss-of-function of KLF11.ResultsIn the BC patient cohort, We demonstrated that KLF11 was higher in highly proliferative BC and lowest in luminal A-like BC. Furthermore, "KLF11-high" BC patients had shorter disease-free survival (DFS), distant-metastasis-free survival (DMFS), and local recurrence-free survival (LRFS). High KLF11 expression remained an independent indicator for DFS and DMFS of BC. The multivariate cox regression-dependent, KLF11-related nomograms of DFS and DMFS showed high accuracy in predicting BC patients' 3-,5- and 10 -year survival probability. Our results indicate that KLF11 might play a pro-tumor role in BC.From the KLF11-BC tumor cells perspective, the cellular functional assays confirmed that KLF11 acts as a pro-tumor transcription factor (TF) in BC cells via promoting proliferation and/or decreasing cell apoptosis. However, due to neoplastic intratumor heterogeneity, different cancer molecular subtypes could have different underlying mechanisms.ConclusionsPrior research has demonstrated that KLF11 expression is lower in BC compared to healthy breast tissue. However, we now could show that high KLF11 expression in BC is probably pro-tumorigenic and is associated with an impaired prognosis. Our study indicates that KLF11, as a transcriptional factor, acts as a new prognostic biomarker and might also be potentially a synergistic or an alternative therapeutic target for conventional targeting treatments of human BC.

Epigenetics play a vital role in early embryo development. Offspring conceived via assisted reproductive technologies (ARTs) have a three times higher risk of epigenetic diseases than naturally conceived children. However, investigations into ART-associated placental histone modifications or sex-stratified analyses of ART-associated histone modifications remain limited. In the current study, we carried out immunohistochemistry, chip-sequence analysis, and a series of in vitro experiments. Our results demonstrated that placentas from intra-cytoplasmic sperm injection (ICSI), but not in vitro fertilization (IVF), showed global tri-methylated-histone-H3-lysine-4 (H3K4me3) alteration compared to those from natural conception. However, for acetylated-histone-H3-lysine-9 (H3K9ac) and acetylated-histone-H3-lysine-27 (H3K27ac), no significant differences between groups could be found. Further, sex -stratified analysis found that, compared with the same-gender newborn cord blood mononuclear cell (CBMC) from natural conceptions, CBMC from ICSI-boys presented more genes with differentially enriched H3K4me3 (n = 198) than those from ICSI-girls (n = 79), IVF-girls (n = 5), and IVF-boys (n = 2). We also found that varying oxygen conditions, RNA polymerase II subunit A (Polr2A), and lysine demethylase 5A (KDM5A) regulated H3K4me3. These findings revealed a difference between IVF and ICSI and a difference between boys and girls in H3K4me3 modification, providing greater insight into ART-associated epigenetic alteration.

Purpose: COX-2 overexpression and elevated levels of prostaglandin E2 (PGE2) play an important role in breast cancer carcinogenesis. Recently, expression of the PGE2 receptor EP3 has been shown to be a positive prognostic factor in breast cancer. This study analyzes the functional aspects of targeting EP3 in breast cancer cell lines. Material and methods: EP3 and EP1 expressions were determined in five breast cancer cell lines on the mRNA- and the protein-level. The selected cell lines were subsequently stimulated for 24-72 hrs with 10-1,000 nM of PGE2, the EP1/EP3 agonist sulprostone and the EP3 antagonist L798,106. Cell proliferation was determined via BrdU-assay, migration via scratch assay, EP3, Gi-protein and p-ERK1/2 expressions via Western blot and cAMP concentrations via ELISA. The Mann-Whitney-U-test was used to test for statistical significance. Results: The cell lines T-47D (EP3 expression 77.7%) and SK-BR-3 (EP3 expression 48.7%) were chosen. EP3 antagonism reduced its expression on SK-BR-3 significantly, while no effect was observed on T-47D. The proliferation and migration of SK-BR-3 cells were significantly reduced due to treatment with the EP1/3 agonist, the EP3 antagonist or a combination of both. Neither agonism nor antagonism influenced cell proliferation or migration in T-47D. In SK-BR-3, EP3 antagonism showed a significant decrease in Gi-protein levels, an increase in cAMP levels, and no significant change in p-ERK1/2 expression. Conclusion: Antagonism of the EP3 receptor results in a reduced proliferation and migration of SK-BR-3 breast cancer cells, potentially mediated via a Gi-protein-cAMP pathway. The results suggest that EP3 plays a role in tumorigenesis. This is in accordance with the cell culture data of other gynecological tumors, but it is conflicting in so far, as positive EP3 expression is clinically a positive prognostic marker in breast cancer. Therefore, other factors may be important in explaining this contradiction.

Sialic acid-binding immunoglobulin-like lectins (Siglecs) are involved in various immune cell-mediated diseases. Their role in cancer is poorly investigated, and research focusses on Siglec-expression on immune cells interacting with tumor cells. This study evaluates the role of Siglec-8 in breast cancer (BC). Siglec-8 expression was analyzed immunohistochemically on 235 primary BC cases and was correlated with clinical and pathological parameters and outcome. Cell culture experiments were performed with various BC cell lines. Siglec-8 was expressed in 215 BC cases and expression was lowest in triple-negative BC. It correlated with estrogen receptor-status, grading and the prognostic factors galectin (Gal)-7 and tumor-associated mucin-1 (TA-MUC1). However, Gal-7 and TA-MUC1 were only prognosticators for clinical outcome in the cohort expressing high (Immunoreactivity score IRS &gt, 3) Siglec-8 levels but not in the low-expressing cohort. Siglec-8 knockdown led to a significantly reduced Gal-7 expression in MCF7 cells. All BC cell lines expressed low Siglec-8-levels, that could be elevated in MCF7 by Peroxisome proliferator-activated receptor (PPARγ)-stimulation. This study demonstrates that Siglec-8 is expressed in BC cells and correlates with known clinical and prognostic parameters. It is probably associated with Gal-7 and TA-MUC1 and might be regulated via PPARγ. Further analyses focusing on functional associations will clarify Siglec-8’s eligibility as a possible therapeutic target.

// Junyan Zhu 1, 2 , Fabian Trillsch 1 , Doris Mayr 3 , Christina Kuhn 1 , Martina Rahmeh 1 , Simone Hofmann 1 , Marianne Vogel 1 , Sven Mahner 1 , Udo Jeschke 1 and Viktoria von Schonfeldt 4 1 Department of Obstetrics and Gynecology, University Hospital, LMU Munich, Munich, Germany 2 Department of Gynecology and Obstetrics, Shanghai Jiao Tong University, School of Medicine, Renji Hospital, Shanghai, China 3 Department of Pathology, University Hospital, LMU Munich, Munich, Germany 4 Division of Gynecological Endocrinology and Reproductive Medicine, Department of Gynecology and Obstetrics, University Hospital, LMU Munich, Munich, Germany Correspondence to: Fabian Trillsch, email: Fabian.Trillsch@med.uni-muenchen.de Keywords: prostaglandin receptor EP3; endometrial cancer; prognosis; estrogen receptor β; Ras Received: May 23, 2017 Accepted: November 16, 2017 Published: December 09, 2017 ABSTRACT Background: Prostaglandin E2 (PGE2) receptor 3 (EP3) regulates tumor cell proliferation, migration, and invasion in numerous cancers. The role of EP3 as a prognostic biomarker in endometrial cancer remains unclear. The primary aim of this study was to analyze the prognostic significance of EP3 expression in endometrial cancer. Methods: We analyzed the EP3 expression of 140 endometrial carcinoma patients by immunohistochemistry. RL95-2 endometrial cancer cell line was chosen from four endometrial cancer cell lines (RL95-2, Ishikawa, HEC-1-A, and HEC-1-B) according to EP3 expression level. Treated with PGE2 and EP3 antagonist, RL95-2 cells were investigated by MTT, BrdU, and wound healing assay for functional assessment of EP3. Results: EP3 staining differed significantly according to WHO tumor grading in both whole cohort (p = 0.01) and the subgroup of endometrioid carcinoma (p = 0.01). Patients with high EP3 expression in their respective tumors had impaired progression-free survival as well as overall survival in both cohorts above. EP3 expression in the overall cohort was identified as an independent prognostic marker for progression-free survival (HR 1.014, 95%CI 1.003-1.024, p = 0.01) when adjusted for age, stage, grading, and recurrence. Treatment with EP3 antagonists induced upregulation of estrogen receptor β and decreased activity of Ras and led to attenuated proliferation and migration of RL95-2 cells. Conclusions: EP3 seems to play a crucial role in endometrial cancer progression. In the context of limited systemic treatment options for endometrial cancer, this explorative analysis identifies EP3 as a potential target for diagnostic workup and therapy.

Implantation consists of a complex process based on coordinated crosstalk between the endometrium and trophoblast. Furthermore, it is known that the microenvironment of this fetal–maternal interface plays an important role in the development of extravillous trophoblast cells. This is mainly due to the fact that tissues mediate embryonic signaling biologicals, among other molecules, prostaglandins. Prostaglandins influence tissue through several cell processes including differentiation, proliferation, and promotion of maternal immune tolerance. The aim of this study is to investigate the potential pathological mechanism of the prostaglandin E2 receptor 4 (EP4) in modulating extravillous trophoblast cells (EVTs) in unexplained recurrent marriage (uRM). Our results indicated that the expression of EP4 in EVTs was decreased in women experiencing uRM. Furthermore, silencing of EP4 showed an inhibition of the proliferation and induced apoptosis in vitro. In addition, our results demonstrated reductions in β- human chorionic gonadotropin (hCG), progesterone, and interleukin (IL)-6, which is likely a result from the activation of the cyclic adenosine monophosphate (cAMP)- cAMP-dependent protein kinase A (PKA)-phosphorylating CREB (pCREB) pathway. Our data might provide insight into the mechanisms of EP4 linked to trophoblast function. These findings help build a more comprehensive understanding of the effects of EP4 on the trophoblast at the fetal–maternal interface in the first trimester of pregnancy.

Peroxisome proliferator-activated receptors (PPARα, PPARβ/δ, and PPARγ) belong to the transcription factor family, and they are highly expressed in all types of trophoblast during pregnancy. The present review discusses currently published papers that are related to the regulation of PPARs via lipid metabolism, glucose metabolism, and amino acid metabolism to affect trophoblast physiological conditions, including differentiation, maturation, secretion, fusion, proliferation, migration, and invasion. Recent pieces of evidence have proven that the dysfunctions of PPARs in trophoblast lead to several related pregnancy diseases such as recurrent miscarriage, preeclampsia, intrauterine growth restriction, and gestational diabetes mellitus. Moreover, the underlying mechanisms of PPARs in the control of these processes have been discussed as well. Finally, this review’s purposes are to provide more knowledge about the role of PPARs in normal and disturbed pregnancy with trophoblast, so as to find PPAR ligands as a potential therapeutic target in the treatment and prevention of adverse pregnancy outcomes.

Backgroud Prostaglandin E2 (PGE2), an inflammatory mediator, modulates cytokines, regulates immune responses in reproductive processes and stimulates inflammatory reactions via the prostaglandin E2 receptor 2 (EP2). However, the regulatory effects of EP2 signaling on trophoblasts and its role in unexplained recurrent miscarriage (uRM) remains unclear. Patients and methods A total of 19 placentas from patients with a history of more than two consecutive pregnancy losses of unknown cause (uRM group) and placentas of 19 healthy patients following a legal termination of their pregnancy were used for PGE2 receptor (EP1, EP2 and EP4) expression analyses via immunohistochemistry. Double immunofluorescence was also used to identify EP2 expressing cells in the decidua. Finally, HTR-8/SVneo cells were used to clarify the role of EP2 in in vitro experiments. Results The expression of EP2 and EP4 was found to be reduced in the syncytiotrophoblast and decidua of uRM patients. A selective EP2 receptor antagonist (PF-04,418,948) reduced the proliferation and secretion of s-hCG, inhibited interleukin -6 (IL-6) and interleukin-8 (IL-8) and up-regulated the production of the tumor necrosis factor-α (TNF-α) and plasminogen activator inhibitor type 1 (PAI-1) in HTR-8/SVneo cells in vitro. Conclusion PGE2-EP2 signaling pathway may represent a novel therapy option for uRM. The involvement of EP2 in uRM acts perhaps via inflammatory cytokines and indicates that the PGE2-EP2 signaling pathway might represent an unexplored etiology for uRM.

Although an inflammatory microenvironment is required for successful implantation, an inflammatory overreaction is one of the causes of unexplained recurrent pregnancy losses (uRPL). Prostaglandin E2 (PGE2) plays a pivotal role in regulating immune balance during early pregnancy, and it can stimulate inflammatory reactions via prostaglandin E2 receptor 3 (EP3). However, the role of PGE2 receptor signaling in the uRPL remains unknown. We aimed to investigate whether EP3 signaling is involved in the mechanism of uRPL. Via immunohistochemistry we could show that the expression of cyclooxygenase-2, EP3 and G protein alpha inhibitor 1 (Gi1) was enhanced in the decidua of the uRPL group in comparison to the control group in first-trimester placentas. In vitro, we demonstrated that sulprostone (an EP1/EP3 agonist) inhibited the secretion of beta-hCG and progesterone in JEG-3 cells and the secretion of beta-hCG in HTR-8/SVneo cells while it induced the expression of plasminogen activator inhibitor type 1 in JEG-3 cells. In addition, PGE2/sulprostone was able to stimulate the expression of Gi1, phosphorylated-extracellular signal-regulated kinases 1/2 (p-ERK1/2) and p53. L-798,106 (an EP3-specific antagonist) suppressed the expression of EP3 and p-ERK1/2 without affecting the secretion of beta-hCG. Elevated activation of EP3 signaling in first-trimester placentas plays an important role in regulating the inflammatory microenvironment, the hormone secretion of extravillous trophoblasts and the remodeling of extracellular matrix in the fetal-maternal interface. L-798,106 might be a ‘potential therapeutic candidate’ for the treatment of uRPL.

Although an inflammatory microenvironment is required for successful implantation, an inflammatory overreaction is one of the causes of unexplained recurrent pregnancy losses (uRPL). Prostaglandin E2 (PGE2) plays a pivotal role in regulating immune balance during early pregnancy, and it can stimulate inflammatory reactions via prostaglandin E2 receptor 3 (EP3). However, the role of PGE2 receptor signaling in the uRPL remains unknown. We aimed to investigate whether EP3 signaling is involved in the mechanism of uRPL. Via immunohistochemistry we could show that the expression of cyclooxygenase-2, EP3 and G protein alpha inhibitor 1 (Gi1) was enhanced in the decidua of the uRPL group in comparison to the control group in first-trimester placentas. In vitro, we demonstrated that sulprostone (an EP1/EP3 agonist) inhibited the secretion of beta-hCG and progesterone in JEG-3 cells and the secretion of beta-hCG in HTR-8/SVneo cells while it induced the expression of plasminogen activator inhibitor type 1 in JEG-3 cells. In addition, PGE2/sulprostone was able to stimulate the expression of Gi1, phosphorylated-extracellular signal-regulated kinases 1/2 (p-ERK1/2) and p53. L-798,106 (an EP3-specific antagonist) suppressed the expression of EP3 and p-ERK1/2 without affecting the secretion of beta-hCG. Elevated activation of EP3 signaling in first-trimester placentas plays an important role in regulating the inflammatory microenvironment, the hormone secretion of extravillous trophoblasts and the remodeling of extracellular matrix in the fetal-maternal interface. L-798,106 might be a ‘potential therapeutic candidate’ for the treatment of uRPL.

Endoplasmic reticulum (ER) stress and autophagy are two basic cell survival mechanisms often occurring in concert. Extensive ER stress in cancer cells deliberately induced by chemotherapeutic drugs may lead to growth arrest and cell death. However, the link between ER stress and autophagy is not well understood. In this study, the treatment of cancer cells with ER stress‐inducing drug nelfinavir resulted in the expression of endogenous mTOR inhibitor sestrin‐2 (SESN2). Upregulation of SESN2 expression was associated with expression of ER stress markers ATF4, ATF3, and CHOP. SESN2 upregulation also occurred in cells treated with the proteasome inhibitor bortezomib. Ectopic expression of ATF4, but not of ATF3 or CHOP, caused transcriptional upregulation of SESN2 expression, indicating expressional regulation of SESN2 by ATF4. Transient overexpression of ectopic SESN2 resulted in mTOR inhibition and autophagy, confirming a link between ER stress, SESN2 upregulation, and mTOR inhibition. Accordingly, cancer cells treated with the ER stress‐inducing agent nelfinavir showed reduced mTOR activity and associated increases in the expression levels of ATF4 and SESN2. These results show that ATF4‐regulated SESN2 expression presents a new link between ER stress and mTOR inhibition and autophagy. mTOR inhibition by nelfinavir, which is currently in clinical trials for cancer patients, may also explain its observed ability to induce autophagy, growth arrest, and radiosensitization in cancer cells.

Inhibins and activins are gonadal peptide hormones of the transforming growth factor-β super family with important functions in the reproductive system. By contrast, the recently identified inhibin βE subunit, primarily expressed in liver cells, appears to exert functions unrelated to the reproductive system. Previously shown downregulation of inhibin βE in hepatoma cells and anti-proliferative effects of ectopic inhibin βE overexpression indicated growth-regulatory effects of inhibin βE. We observed a selective re-expression of the inhibin βE subunit in HepG2 hepatoblastoma cells, MCF7 breast cancer cells, and HeLa cervical cancer cells under endoplasmic reticulum stress conditions induced by tunicamycin, thapsigargin, and nelfinavir. Analysis of XPB1 splicing and ATF4 activation revealed that inhibin βE re-expression was associated with induction of the endoplasmic reticulum stress reaction by these drugs. Transfection of an ATF4 expression plasmid specifically induced inhibin βE expression in HeLa cells and indicates inhibin βE as a hitherto unidentified target gene of ATF4, a key transcription factor of the endoplasmic reticulum stress response. Therefore, the inhibin βE subunit defines not only a new player but also a possible new marker for drug-induced endoplasmic reticulum stress.

In the original publication of the article, the name of first author was misspelled. The correct name has been copied below.

Proteasome inhibitors and protease inhibitors are currently being discussed to be useful to sensitize drug-resistant cancer cells to chemotherapeutic agents or to act independently as single agents on drug-resistant cancer cells. We tested the effect of the clinically applied HIV protease inhibitor nelfinavir on ovarian cancer cells. Nelfinavir efficiently induced cell death in carboplatin-sensitive (SKOV3, OV-GH-5) and carboplatin-resistant (OVCAR3, OV-GH-1) ovarian cancer cell lines as well as in cancer biopsies and ascites samples from patients with recurrent ovarian cancer. Nelfinavir significantly changed the morphology of ovarian cancer cells, resulting in formation of large ER-derived vacuoles and induced upregulation of the hsp70 heat shock family member BiP (GRP78) which accumulated within swollen ER membranes. Upregulation of BiP and phosphorylation of eIF2alpha indicated induction of the unfolded protein response, which can cause cell cycle arrest and apoptosis. Correspondingly, we observed downregulation of cell cycle regulatory proteins after nelfinavir treatment, especially that of cyclin D3, and induction of apoptosis as confirmed by annexin binding. Because nelfinavir represents an already approved drug for use in humans with HIV infection, it could rapidly be tested in clinical studies as a potential treatment strategy against drug-resistant ovarian cancer.

Lapatinib (GW572016) is a selective inhibitor of both epidermal growth factor receptor (EGFR) and HER-2 tyrosine kinases. Here, we explore the therapeutic potential of lapatinib by testing its effect on tumor cell growth in a panel of 31 characterized human breast cancer cell lines, including trastuzumab-conditioned HER-2-positive cell lines. We further characterize its activity in combination with trastuzumab and analyze whether EGFR and HER-2 expression or changes induced in the activation of EGFR, HER-2, Raf, AKT, or extracellular signal-regulated kinase (ERK) are markers of drug activity. We report that concentration-dependent antiproliferative effects of lapatinib were seen in all breast cancer cell lines tested but varied significantly between individual cell lines with up to 1,000-fold difference in the IC50s (range, 0.010-18.6 μmol/L). Response to lapatinib was significantly correlated with HER-2 expression and its ability to inhibit HER-2, Raf, AKT, and ERK phosphorylation. Long-term in vivo lapatinib studies were conducted with human breast cancer xenografts in athymic mice. Treatment over 77 days resulted in a sustained and significant reduction in xenograft volume compared with untreated controls. For the combination of lapatinib plus trastuzumab, synergistic drug interactions were observed in four different HER-2-overexpressing cell lines. Moreover, lapatinib retained significant in vitro activity against cell lines selected for long-term outgrowth (>9 months) in trastuzumab-containing (100 μg/mL) culture medium. These observations provide a clear biological rationale to test lapatinib as a single agent or in combination with trastuzumab in HER-2-overexpressing breast cancer and in patients with clinical resistance to trastuzumab. (Cancer Res 2006; 66(3): 1630-9)

Optimal T-cell activation depends on the antigen-specific signal mediated by the TCR and engagement of costimulatory receptors such as CD28. CTLA-4, a homologous counterpart of CD28, is considered to be a crucial inhibitory receptor. To test its function separately from CD28 in an antigen-driven and ligand-specific model, we stably transfected the T-cell hybridomas A1.1 and DO11.10, which lack significant endogenous CD28 or CTLA-4 expression, with wild-type CTLA-4 (CTLA-4 WT) and a construct lacking the cytoplasmic tail (tailless [TL]). Functional studies were carried out by co-incubation with APC expressing the B7 ligands for CTLA-4 and appropriate MHC molecules loaded with their cognate antigens. IL-2 production on costimulation of CTLA-4WT and TCR did not differ significantly from untransfected controls. However, coligation of TCR and CTLA-4TL resulted in a vigorous IL-2 response specific for the interaction of CTLA-4 with B7. Thus, lack of the cytoplasmic tail converted CTLA-4 into a costimulatory receptor. This indicates that the CTLA-4 inhibitory function may not be attributable to sequestration of the common B7 ligands when competing with CD28. Rather, ligation of B7 by the CTLA-4 extracellular domain can enhance TCR activation, whereas in the full-length receptor, inhibitory signals mediated by the cytoplasmic domain may override this activation.

e17050 Background: New therapeutic approaches for platinum-resistant ovarian cancer patients are urgently needed. In this context, Wnt signaling appears to be a promising target so that inhibition of this pathway in platinum-resistant cell lines was aim of the present study. Methods: The ovarian cancer cell line A2780 and its platinum-resistant clone A2780cis were treated with different concentrations of Wnt singaling inhibitors SB216761, XAV939, and triptolides. Metabolic activity and cell viability was estimated by MTT cell proliferation assays. Immunohistochemistry for ß-Catenin visualized activity of the Wnt pathway. Results: MTT proliferation tests revealed an impaired proliferation following treatment with all three agents. While triptolides already led to significantly reduced metabolic activity after 48h, this effect was seen for SB216761 and XAV939 not before 72h. Immunohistochemistry for ß-Catenin confirmed inhibition of Wnt signaling. Following XAV939 treatment of A2780cis, ß-Catenin signals shifted from the nucleus towards the cell membrane. Conclusions: Re-sensitizing platinum-resistant ovarian cancer cells for platinum-based chemotherapy by inhibition of Wnt signaling seems to be mechanism visualized by the translocation of ß-Catenin from the nucleus towards the cell membrane. In this context, a dose-dependent response was noted for XAV939. Inhibition of Wnt Signaling appears to be a prospective therapeutic approach for platinum-resistant ovarian cancer patients.

HIV protease inhibitors are currently being discussed to be useful as new and alternative anti-cancer agents, especially as second line treatments for chemo-resistant human cancer types. Among three clinically applied HIV protease inhibitors tested, we found a high efficacy of nelfinavir on ovarian cancer cells, accompanied by apoptosis (annexin binding) and necrosis (propidium iodide permeability). In vitro, at concentrations used to induce cell death in ovarian cancer cells, nelfinavir had no effect on the cellular viability of fibroblasts or peripheral blood mononuclear leukocytes. Nelfinavir sensitized ovarian cancer cells to treatment with an apoptosis-inducing TRAIL receptor antibody due to upregulation of the TRAIL receptor DR5 as shown by RT-PCR and FACScan analysis. We conclude that nelfinavir, an already approved drug, is a highly efficient agent against ovarian cancer cells and could sensitize ovarian cancer cells to TRAIL treatment, either therapeutically applied or endogenously produced by cells of the immune system.

Bortezomib, an approved drug for the treatment of certain haematological neoplasms, is currently being tested in clinical trials as a potential therapeutic agent against several types of solid cancer, including ovarian cancer. We have analyzed the effect of bortezomib on ovarian cancer cells and tissue explants either as a single agent or in combination with carboplatin, taxol, or TRAIL (tumor necrosis factor-related apoptosis-inducing ligand). Bortezomib alone efficiently induced apoptosis in ovarian cancer cells. Apoptosis was preceded by an upregulation of the endoplasmic reticulum stress sensor ATF3, and increased the expression of cytoplasmic heat shock proteins. Bortezomib enhanced the sensitivity of ovarian cancer cells and tissue explants to an apoptosis-inducing TRAIL receptor antibody by upregulating the TRAIL receptor DR5. In contrast to the synergistic effect observed for TRAIL, the efficacy of the taxol treatment was reduced by bortezomib, and bortezomib inhibited the G2/M phase accumulation of ovarian cancer cells treated with taxol. Bortezomib alone or in combination with taxol induced a cell cycle arrest within the S phase, and downregulation of cdk1, a cyclin-dependent kinase that is necessary for the entry into the M phase. Thus, bortezomib can be regarded as a promising agent for the treatment of ovarian cancer and could either be administered as a single agent or in combination with TRAIL. However, a combination treatment with taxanes may not be beneficial and may even be less effective.