Search

Malignant ascites is commonly produced in advanced epithelial ovarian cancer (EOC) and serves as unique microenvironment for tumour cells. Acellular ascites fluid (AAF) is rich in signalling molecules and has been proposed to play a role in the induction of chemoresistance. Through in vitro testing of drug sensitivity and by assessing intracellular phosphorylation status in response to mono- and combination treatment of five EOC cell lines after incubation with AAFs derived from 20 different patients, we investigated the chemoresistance-inducing potential of ascites. We show that the addition of AAFs to the culture media of EOC cell lines has the potential to induce resistance to standard-of-care drugs (SCDs). We also show that AAFs induce time- and concentration-dependent activation of downstream signalling to signal transducer and activator of transcription 3 (STAT3), and concomitantly altered phosphorylation of mitogen-activated protein kinase kinase (MEK), phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) and nuclear factor NF-kappa-B (NFκB). Antibodies targeting the interleukin-6 receptor (IL6R) effectively blocked phosphorylation of STAT3 and STAT1. Treatments with SCDs were effective in reducing cell viability in only a third of 30 clinically relevant conditions examined, defined as combinations of drugs, different cell lines and AAFs. Combinations of SCDs and novel therapeutics such as trametinib, fludarabine or rapamycin were superior in another third. Notably, we could nominate effective treatment combinations in almost all conditions except in 4 out of 30 conditions, in which trametinib or fludarabine showed higher efficacy alone. Taken together, our study underscores the importance of the molecular characterisation of individual patients' AAFs and the impact on treatment resistance as providing clinically meaningful information for future precision treatment approaches in EOC., (© 2024 The Author(s). Molecular Oncology published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

The quinoline-3-carboxamide ABR-215757 (5757) is in clinical development for the treatment of human SLE and has shown efficacy in several mouse models of T cell-mediated inflammatory autoimmune disease. The goal of this study was to determine the impact of 5757 on steady state immune cells. We show that the number of splenic CD4 dendritic cells (DCs) was reduced in 5757-treated mice, while there was no effect on other splenic DC populations, on DCs in lymph nodes or on lymphocytes. This reduction was fully reversible and the kinetics of CD4 DC loss during exposure and recovery after withdrawal of treatment was identical. The loss of CD4 DCs was neither caused by reduced proliferation nor by increased apoptosis. CD4 DCs reside in the splenic marginal zone, but the loss of these cells did not influence other cell populations at this site. The similar kinetics of the decay and repopulation of the splenic CD4 DC compartment suggests that the reduced number of CD4 DC in 5757 treated mice may be a result of blockade of CD4 DC precursor development in the spleen and not of toxicity. Alternatively, induced emigration of CD4 DC to the periphery, or an interference with adherence of these cells in the spleen marginal zone, may also explain our data., ((c) 2010 Elsevier B.V. All rights reserved.)

Repeated immunization of mice with bacterial superantigens induces extensive deletion and anergy of reactive CD4 T cells. Here we report that the in vitro proliferation anergy of CD4 T cells from TCR transgenic mice immunized three times with staphylococcal enterotoxin B (SEB) (3 x SEB) is partially due to an increased frequency of Foxp3(+) CD4 T cells. Importantly, reduced number of conventional CD25(-) Foxp3(-) cells, rather than conversion of such cells to Foxp3(+) cells, was the cause of that increase and was also seen in mice repeatedly immunized with OVA (3 x OVA) and OVA-peptide (OVAp) (3 x OVAp). Cell-transfer experiments revealed profound but transient anergy of CD4 T cells isolated from 3 x OVAp and 3x SEB mice. However, the in vivo anergy was CD4 T-cell autonomous and independent of Foxp3(+) Treg. Finally, proliferation of transferred CD4 T cells was inhibited in repeatedly immunized mice but inhibition was lost when transfer was delayed, despite the maintenance of elevated frequency of Foxp3(+) cells. These data provide important implications for Foxp3(+) cell-mediated tolerance in situations of repeated antigen exposure such as human persistent infections.