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.

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.

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.

Precision cancer medicine with small tyrosine kinase inhibitors (TKIs) directed toward oncogenic drivers, are important treatment regimens for solid tumours. The epidermal growth factor receptor (EGFR)‐TKI osimertinib is a preferred therapy for patients with non‐small cell lung cancer (NSCLC) driven by activating mutations in EGFR , unfortunately responses are heterogeneous. This calls for non‐invasive methods to predict or monitor treatment response, for example, via biomarker analyses in blood. To reveal such putative biomarkers, we analysed the proteome of extracellular vesicles (EVs) from osimertinib resistant or responsive NSCLC cells in vitro and from EVs isolated from serum samples of NSCLC patients treated with osimertinib in second line within the phase II clinical trial TREM. The protein cargo of the EVs was analysed by mass spectrometry (MS) and proximity extension assay (PEA). Western blotting, ELISA and single vesicle analysis was performed to validate and further confirm the expression of certain proteins. MS profiling of the NSCLC cells and their released EVs revealed a protein signature associated with osimertinib refractoriness. Among them were CSPG4, HSPG2, MCAM, L1CAM, TAGLN, THBS1 and TNC. GO‐pathway analysis related several of these proteins to the focal adhesion and proteoglycan in cancer pathways. Some of these proteins, including CSPG4, which when suppressed by transient siRNA transfection in NSCLC cells resulted in reduced cell viability, were expressed also in EVs from serum of the NSCLC patients. Moreover, PEA profiling of the serum‐isolated EVs revealed signatures associated with immune cells, best response and/or progression‐free survival, including PD‐L1, CD73/NT5E, FR‐alpha/FOLR1, LAMP3, FASLG1 and ANXA1. In summary, we demonstrate that protein profiling of EVs in relation to osimertinib refractoriness has the potential to identify possible biomarkers that can indicate osimertinib treatment resistance, for example, CSPG4, HSPG2, TAGLN, TNC, THBS1, ANXA1 and CD73/NT5E. Studies in expanded cohorts should be conducted to further validate these putative osimertinib biomarkers.

Ovarian cancer (OvCa) is an aggressive disease usually treated with cisplatin (CDDP)-based therapy. However, among the different types of cancers treated with CDDP, OvCa commonly develops chemoresistance to this treatment. The small extracellular vesicles (sEVs) play a central role in chemoresistance. In response to chemotherapy, resistant cells secrete sEVs named chemo-sEVs characterized by specific cargo landscape content involved in the transfer of chemoresistance to recipient cells. sEVs encompass a variety of vesicle types, including exosomes, and are formed as intraluminal vesicles (ILVs) within multivesicular endosomes (MVEs). MVEs follow at least two trafficking pathways regulated by RAB GTPase family members; 1) a secretory pathway where MVEs fuse with the plasma membrane (PM) for sEVs secretion, where RAB27A is the most studied; 2) a degradative pathway where MVEs fuse with lysosomes, an event controlled by RAB7. There is growing evidence suggesting that a loss of lysosomal function can increase sEVs secretion; however, whether sEVs secretion and the transfer of CDDP chemoresistance in OvCa is the result of a fine regulation between these two MVEs trafficking pathways is unknown. In this work, we study the status of these two pathways, between CDDP-sensitive (A2780) and CDDP-resistant (A2780cis) OvCa cells. We found A2780cis cells have an increased number of MVEs and ILVs structures, together with higher levels of ESCRTs machinery components and RAB27A, compared to A2780 cells. Moreover, CDDP promotes the secretion of chemo-sEVs in A2780cis cells. Interestingly, chemo-sEVs contain a high number of proteins related to DNA damage response. In addition, we determine A2780cis cells have a poor lysosomal function with reduced levels of RAB7. Surprisingly, silencing of RAB27A in A2780cis cells was found to be sufficient to restore lysosomal function and levels of RAB7 in A2780cis cells, switching into an A2780-like cellular phenotype. Next, we found rapamycin, a potent enhancer of lysosomal function, reduced the secretion of chemo-sEVs. Taken together, these results indicate that the secretion of chemo-sEVs in OvCa cells is determined by the balance between secretory MVEs and MVEs that are destined for lysosomal degradation. Thus, our results suggest that adjusting this balance between these two MVEs trafficking pathways could be a promising strategy for overcoming CDDP chemoresistance in OvCa. Graphical