Phosphorylation of Endothelin-Converting Enzyme-1c at Serines 18 and 20 by CK2 Promotes Aggressiveness Traits in Colorectal Cancer Cells.

Endothelin-converting enzyme-1 (ECE1) activates the endothelin-1 peptide, which upregulates pathways that are related to diverse hallmarks of cancer. ECE1 is expressed as four isoforms differing in their N-terminal domains. Protein kinase CK2 phosphorylates the N-terminus of isoform ECE1c, enhancing its stability and promoting invasiveness of colorectal cancer cells. However, the specific residues in ECE1c that are phosphorylated by CK2 and how this phosphorylation promotes invasiveness was unknown. Here we demonstrate that Ser-18 and Ser-20 are the bona fide residues phosphorylated by CK2 in ECE1c. Thus, biphospho-mimetic ECE1cDD and biphospho-resistant ECE1cAA mutants were constructed and stably expressed in different colorectal cancer cells through lentiviral transduction. Biphospho-mimetic ECE1cDD displayed the highest stability in cells, even in the presence of the specific CK2 inhibitor silmitasertib. Concordantly, ECE1cDD-expressing cells showed enhanced hallmarks of cancer, such as proliferation, migration, invasiveness, and self-renewal capacities. Conversely, cells expressing the less-stable biphospho-resistant ECE1cAA showed a reduction in these features, but also displayed an important sensitization to 5-fluorouracil, an antineoplastic agent traditionally used as therapy in colorectal cancer patients. Altogether, these findings suggest that phosphorylation of ECE1c at Ser-18 and Ser-20 by CK2 promotes aggressiveness in colorectal cancer cells. Therefore, phospho-ECE1c may constitute a novel biomarker of poor prognosis and CK2 inhibition may be envisioned as a potential therapy for colorectal cancer patients.

Exosomes released upon mitochondrial ASncmtRNA knockdown reduce tumorigenic properties of malignant breast cancer cells.

During intercellular communication, cells release extracellular vesicles such as exosomes, which contain proteins, ncRNAs and mRNAs that can influence proliferation and/or trigger apoptosis in recipient cells, and have been proposed to play an essential role in promoting invasion of tumor cells and in the preparation of metastatic niches. Our group proposed the antisense non-coding mitochondrial RNA (ASncmtRNA) as a new target for cancer therapy. ASncmtRNA knockdown using an antisense oligonucleotide (ASO-1537S) causes massive death of tumor cells but not normal cells and strongly reduces metastasis in mice. In this work, we report that exosomes derived from ASO-1537S-treated MDA-MB-231 breast cancer cells (Exo-1537S) inhibits tumorigenesis of recipient cells, in contrast to exosomes derived from control-ASO-treated cells (Exo-C) which, in contrast, enhance these properties. Furthermore, an in vivo murine peritoneal carcinomatosis model showed that Exo-1537S injection reduced tumorigenicity compared to controls. Proteomic analysis revealed the presence of Lactadherin and VE-Cadherin in exosomes derived from untreated cells (Exo-WT) and Exo-C but not in Exo-1537S, and the latter displayed enrichment of proteasomal subunits. These results suggest a role for these proteins in modulation of tumorigenic properties of exosome-recipient cells. Our results shed light on the mechanisms through which ASncmtRNA knockdown affects the preparation of breast cancer metastatic niches in a peritoneal carcinomatosis model.

Small Extracellular Vesicles Released from Ovarian Cancer Spheroids in Response to Cisplatin Promote the Pro-Tumorigenic Activity of Mesenchymal Stem Cells.

Despite the different strategies used to treat ovarian cancer, around 70% of women/patients eventually fail to respond to the therapy. Cancer stem cells (CSCs) play a role in the treatment failure due to their chemoresistant properties. This capacity to resist chemotherapy allows CSCs to interact with different components of the tumor microenvironment, such as mesenchymal stem cells (MSCs), and thus contribute to tumorigenic processes. Although the participation of MSCs in tumor progression is well understood, it remains unclear how CSCs induce the pro-tumorigenic activity of MSCs in response to chemotherapy. Small extracellular vesicles, including exosomes, represent one possible way to modulate any type of cell. Therefore, in this study, we evaluate if small extracellular vesicle (sEV) derived from ovarian cancer spheroids (OCS), which are enriched in CSCs, can modify the activity of MSCs to a pro-tumorigenic phenotype. We show that sEV released by OCS in response to cisplatin induce an increase in the migration pattern of bone marrow MSCs (BM-MSCs) and the secretion interleukin-6 (IL-6), interleukin-8 (IL-8), and vascular endothelial growth factor A (VEGFA). Moreover, the factors secreted by BM-MSCs induce angiogenesis in endothelial cells and the migration of low-invasive ovarian cancer cells. These findings suggest that cisplatin could modulate the cargo of sEV released by CSCs, and these exosomes can further induce the pro-tumorigenic activity of MSCs.

Angiogenic Properties of Menstrual Stem Cells Are Impaired in Women with a History of Preeclampsia.

Preeclampsia is a pregnancy-specific disorder defined by the new onset of hypertension and proteinuria after 20 weeks of gestation. Although its precise etiology is still unknown, there is evidence suggesting that it may be a consequence of impaired decidual and stromal cell function. Recently, a stem cell population derived from endometrial tissue and isolated from menstrual effluent called menstrual stem cells (MenSCs) has been identified. MenSCs exhibit important angiogenic and inflammatory properties that may contribute to both normal and pathological complications of implantation and placentation, including preeclampsia. We hypothesized that the angiogenic and inflammatory activity of MenSCs is altered in women who have a past history of preeclampsia and that this phenotype persists postpartum. The primary outcome measures were stromal progenitor cell formation, in vitro induction of endothelial tube formation, and release of proinflammatory cytokines. MenSCs obtained from women with a previous normal or preeclamptic pregnancy displayed similar phenotypic characteristics, tri-differentiation capacity, and proliferation. MenSCs derived from women who had preeclampsia on their previous pregnancy had reduced angiogenic capacity (~30% fewer junctions and nodes, p < 0.05) and stromal progenitor cell formation (<50% measured at a serial dilution of 1 : 10.000, p < 0.05) when compared to controls. In vitro, MenSCs obtained from patients with a history of preeclampsia expressed less endoglin and secreted less VEGF but more IL-6 than controls did. These data are consistent with the hypothesis that the angiogenic and inflammatory properties of MenSCs of women with a previous pregnancy complicated by preeclampsia have reduced angiogenic capacity and are more proinflammatory than those of MenSCs of women with a previous normal pregnancy. This altered phenotype of MenSCs observed following preeclampsia could either be present before the development of the pathology, predisposing the endometrial milieu to and consequently leading to limited vascular remodeling, or be a consequence of preeclampsia itself. The former may afford opportunity for targeted therapeutic intervention; the latter, a putative biomarker for future risk of pregnancy complications.