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Background: Obesity impairs a variety of cell types including adipose-derived mesenchymal stem cells (ASCs). ASCs are indispensable for tissue homeostasis/repair, immunomodulation, and cell renewal. It has been demonstrated that obese ASCs are defective in differentiation, motility, immunomodulation, and replication. We have recently reported that some of these defects are linked to impaired primary cilia, which are unable to properly convey and coordinate a variety of signaling pathways. We hypothesized that the rescue of the primary cilium in obese ASCs would restore their functional properties.
Methods: Obese ASCs derived from subcutaneous and visceral adipose tissues were treated with a specific inhibitor against Aurora A or with an inhibitor against extracellular signal-regulated kinase 1/2 (Erk1/2). Multiple molecular and cellular assays were performed to analyze the altered functionalities and their involved pathways.
Results: The treatment with low doses of these inhibitors extended the length of the primary cilium, restored the invasion and migration potential, and improved the differentiation capacity of obese ASCs. Associated with enhanced differentiation ability, the cells displayed an increased expression of self-renewal/stemness-related genes like SOX2, OCT4, and NANOG, mediated by reduced active glycogen synthase kinase 3 β (GSK3β).
Conclusion: This work describes a novel phenomenon whereby the primary cilium of obese ASCs is rescuable by the low-dose inhibition of Aurora A or Erk1/2, restoring functional ASCs with increased stemness. These cells might be able to improve tissue homeostasis in obese patients and thereby ameliorate obesity-associated diseases. Additionally, these functionally restored obese ASCs could be useful for novel autologous mesenchymal stem cell-based therapies.
The oncogene B-cell lymphoma 6 (BCL6) is associated with lymphomagenesis. Intriguingly, its expression is increased in preeclamptic placentas. Preeclampsia is one of the leading causes of maternal and perinatal mortality and morbidity. Preeclamptic placentas are characterized by various defects like deregulated differentiation and impaired fusion of trophoblasts. Its pathogenesis is however not totally understood. We show here that BCL6 is present throughout the cell fusion process in the fusogenic trophoblastic cell line BeWo. Suppression of BCL6 promotes trophoblast fusion, indicated by enhanced levels of fusion-related β-hCG, syncytin 1 and syncytin 2. Increased mRNA levels of these genes could also be observed in primary term cytotrophoblasts depleted of BCL6. Conversely, stable overexpression of BCL6 reduces the fusion capacity of BeWo cells. These data suggest that an accurately regulated expression of BCL6 is important for proper differentiation and successful syncytialization of trophoblasts. While deregulated BCL6 is linked to lymphomagenesis by blocking lymphocyte terminal differentiation, increased BCL6 in the placenta contributes to the development of preeclampsia by impairing trophoblast differentiation and fusion.
Impact of Docetaxel on blood-brain barrier function and formation of breast cancer brain metastases
(2019)
Background: Breast cancer (BC) is the most frequent malignant tumor in females and the 2nd most common cause of brain metastasis (BM), that are associated with a fatal prognosis. The increasing incidence from 10% up to 40% is due to more effective treatments of extracerebral sites with improved prognosis and increasing use of MRI in diagnostics. A frequently administered, potent chemotherapeutic group of drugs for BC treatment are taxanes usually used in the adjuvant and metastatic setting, which, however, have been suspected to be associated with a higher incidence of BM. The aim of our study was to experimentally analyze the impact of the taxane docetaxel (DTX) on brain metastasis formation, and to elucidate the underlying molecular mechanism.
Methods: A monocentric patient cohort was analyzed to determine the association of taxane treatment and BM formation. To identify the specific impact of DTX, a murine brain metastatic model upon intracardial injection of breast cancer cells was conducted. To approach the functional mechanism, dynamic contrast-enhanced MRI and electron microscopy of mice as well as in-vitro transendothelial electrical resistance (TEER) and tracer permeability assays using brain endothelial cells (EC) were carried out. PCR-based, immunohistochemical and immunoblotting analyses with additional RNA sequencing of murine and human ECs were performed to explore the molecular mechanisms by DTX treatment.
Results: Taxane treatment was associated with an increased rate of BM formation in the patient cohort and the murine metastatic model. Functional studies did not show unequivocal alterations of blood-brain barrier properties upon DTX treatment in-vivo, but in-vitro assays revealed a temporary DTX-related barrier disruption. We found disturbance of tubulin structure and upregulation of tight junction marker claudin-5 in ECs. Furthermore, upregulation of several members of the tubulin family and downregulation of tetraspanin-2 in both, murine and human ECs, was induced.
Conclusion: In summary, a higher incidence of BM was associated with prior taxane treatment in both a patient cohort and a murine mouse model. We could identify tubulin family members and tetraspanin-2 as potential contributors for the destabilization of the blood-brain barrier. Further analyses are needed to decipher the exact role of those alterations on tumor metastatic processes in the brain.