Background How exosomal microRNAs (miRNAs) derived from macrophages contribute to the development of drug resistance in the context of the hypoxic tumor microenvironment in epithelial ovarian cancer (EOC) remains poorly understood. Methods The miRNA levels were detected by qRT-PCR. Protein levels of HIF-1α, CD163 and PTEN-PI3K/AKT pathway were assessed by Western blot (WB) and Immunohistochemistry (IHC). Exosomes were isolated, and then confirmed by Transmission electron microscopy (TEM), Nanoparticle Tracking Analysis (NTA) and WB. Internalization of macrophages-secreted exosomes in EOC cells was detected by Confocal microscope. Subsequently, Dual-luciferase reporter assay verified PTEN was the target of miR-223. Gain- and loss-of-function experiments, rescue experiments, and SKOV3 xenograft models were performed to uncover the underlying mechanisms of miR-223 and PTEN-PI3K/AKT pathway, as well as the exosomal miR-223 in inducing multidrug resistance in vitro and in vivo. Results Here, we showed hypoxic EOC cells triggered macrophages recruitment and induced macrophages into a tumor-associated macrophage (TAM)-like phenotype; exosomes derived from hypoxic macrophages enhanced the malignant phenotype of EOC cells, miR-223 was enriched in exosomes released from macrophages under hypoxia, which could be transferred to the co-cultivated EOC cells, accompanied by enhanced drug resistant of EOC cells. Besides, results from a functional assay revealed that exosomal miR-223 derived from macrophages promoted the drug resistance of EOC cells via the PTEN-PI3K/AKT pathway both in vivo and in vitro. Furthermore, patients with high HIF-1a expression had statistically higher CD163+ cell infiltration and intertumoral levels of miR-223. Finally, circulating exosomal miR-223 levels were closely related to the recurrence of EOC. Conclusions These data indicate a unique role of exosomal miR-223 in the cross-talk between macrophages and EOC cells in chemotherapy resistance, through a novel exosomal miR-223/PTEN-PI3K/AKT signaling pathway. Electronic supplementary material The online version of this article (10.1186/s13046-019-1095-1) contains supplementary material, which is available to authorized users.

Neurons in the central nervous system (CNS) fail to regenerate axons after injuries due to the diminished intrinsic axon growth capacity of mature neurons and the hostile extrinsic environment composed of a milieu of inhibitory factors. Recent studies revealed that targeting a particular group of extracellular inhibitory factors is insufficient to trigger long-distance axon regeneration. Instead of antagonizing the growing list of impediments, tackling a common target that mediates axon growth inhibition offers an alternative strategy to promote axon regeneration. Neuronal growth cone, the machinery that derives axon extension, is the final converging target of most, if not all, growth impediments in the CNS. In this study, we aim to promote axon growth by directly targeting the growth cone. Here we report that pharmacological inhibition or genetic silencing of nonmuscle myosin II (NMII) markedly accelerates axon growth over permissive and nonpermissive substrates, including major CNS inhibitors such as chondroitin sulfate proteoglycans and myelin-associated inhibitors. We find that NMII inhibition leads to the reorganization of both actin and microtubules (MTs) in the growth cone, resulting in MT reorganization that allows rapid axon extension over inhibitory substrates. In addition to enhancing axon extension, we show that local blockade of NMII activity in axons is sufficient to trigger axons to grow across the permissive-inhibitory border. Together, our study proposes NMII and growth cone cytoskeletal components as effective targets for promoting axon regeneration.myelin | glial scar | multi-compartment neuronal culture chamber

The imbalance of Th17/Treg cell populations has been suggested to be involved in the regulation of rheumatoid arthritis (RA) pathogenesis; however, the mechanism behind this phenomenon remains unclear. Recent studies have shown how microRNAs (miRNAs) are important regulators of immune responses and are involved in the development of a variety of inflammatory diseases, including RA. In this study, we demonstrated that the frequencies of CD3+CD4+IL-17+Th17 cells were significantly higher, and CD4+CD25+FOXP3+ Treg cells significantly lower in peripheral blood mononuclear cells from RA patients. Detection of cytokines from RA patients revealed an elevated panel of pro-inflammatory cytokines, including IL-17, IL-6, IL-1β, TNF-α and IL-22, which carry the inflammatory signature of RA and are crucial in the differentiation and maintenance of pathogenic Th17 cells and dysfunction of Treg cells. However, the level of miR-21 was significantly lower in RA patients, accompanied by the increase in STAT3 expression and activation, and decrease in STAT5/pSTAT5 protein and Foxp3 mRNA levels. Furthermore, lipopolysaccharide stimulation up-regulated miR-21 expression from healthy controls, but down-regulated miR-21 expression from RA patients. Therefore, we speculate that miR-21 may be part of a negative feedback loop in the normal setting. However, miR-21 levels decrease significantly in RA patients, suggesting that this feedback loop is dysregulated and may contribute to the imbalance of Th17 and Treg cells. MiR-21 may thus serve as a novel regulator in T-cell differentiation and homoeostasis, and provides a new therapeutic target for the treatment of RA.

a b s t r a c tMicroRNAs (miRNA) have emerged as key players in carcinogenesis. Here, we investigated the role of miR-137 in the pathogenesis of lung cancer. The downregulation of miR-137 in lung cancer cells could be rescued following inhibition of DNA methylation. Ectopic expression of miR-137 in lung cancer cells significantly downregulated Cdc42, Cdk6 and induced G1 cell cycle arrest, leading to a significant decrease in cell growth in vivo and in vitro. Further, both Cdc42 and Cdk6 were confirmed as targets of miR-137. Crown

Epithelial-mesenchymal transition (EMT) has an established role in promoting tumor progression and the acquisition of therapeutic resistance. Here, the EMT phenotype was detected in cisplatin-resistant ovarian cancer tissues and cell lines, and correlated with decreased miR-186 expression, increased Twist1 expression, chemoresistance and poor prognosis in epithelial ovarian cancer (EOC) patients. Introducing miR-186 into EOC cells led to a reduction in twist family bHLH transcription factor 1 (Twist1) expression along with morphological, functional and molecular changes consistent with mesenchymal-to-epithelial transition, G1 cell-cycle arrest and enhanced cell apoptosis, which consequently rendered the cells more sensitive to cisplatin in vitro and in vivo. Furthermore, luciferase reporter and rescue assay results showed that the EMT and drug resistance reversal in response to miR-186 was mediated by Twist1. Collectively, these findings implicate miR-186 as an attractive candidate for overcoming chemoresistance in ovarian cancer therapy.

Multidrug resistance (MDR) remains a major obstacle to effective chemotherapy treatment in ovarian cancer. In our study, paclitaxel-resistant ovarian cancer patients and cell lines had decreased miR-145 levels and expressed high levels of Sp1 and Cdk6. Introducing miR-145 into SKOV3/PTX and A2780/PTX cells led to a reduction in Cdk6 and Sp1 along with downregulation of P-gp and pRb. These changes resulted in increased accumulation of antineoplastic drugs and G1 cell cycle arrest, which rendered the cells more sensitive to paclitaxel in vitro and in vivo. These effects could be reversed by reintroducing Sp1 or Cdk6 into cells expressing high levels of miR-145, resulting in restoration of P-gp and pRb levels. Furthermore, we confirmed that both Cdk6 and Sp1 are targets of miR-145. Intriguingly, demethylation with 5-aza-dC led to reactivation of miR-145 expression in drug-resistant ovarian cancer cell lines, which also resulted in increased sensitivity to paclitaxel. Collectively, these findings begin to elucidate the role of miR-145 as an important regulator of chemoresistance in ovarian cancer by controlling both Cdk6 and Sp1.Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy. Because of the absence of early symptoms, most patients are diagnosed at an advanced stage. Chemotherapy is one of the most frequently used treatment modalities for advanced-stage ovarian cancer patients. Although initial responsiveness to first-line chemotherapy consisting of a platinum-containing compound in combination with paclitaxel (PTX) is high, up to 80% of patients eventually relapse and become platinum/taxane resistant. Therefore, a better understanding of the mechanisms involved in MDR ovarian cancer and more effective therapeutic approaches are immediately required.1 Multiple mechanisms that mediate intrinsic or acquired resistance to paclitaxel have been identified. A major contributor to resistance is the active export of drugs by transmembrane polysubstrate efflux pumps that prevent drugs from reaching their intracellular targets, and a highly studied member of this family is multidrug resistance-1 (MDR1). MDR1 encodes for the membrane transporter P-glycoprotein (P-gp), whose substrates included a wide array of toxins and commonly used chemotherapeutic agents, including taxanes and anthracyclines. 2 Cell cycle dysregulation is another common molecular finding in ovarian cancer, and the cyclin-dependent kinases (Cdks) represent attractive targets in this pathway. For example, inhibition of Cdk6, one of the powerful cell cycle progression regulators, showed encouraging effects in animal experiments and clinical trials. MicroRNAs (miRNAs) are small, noncoding RNA molecules that negatively regulate a large number of proteinencoding genes via either mRNA degradation or translational silencing. Evidence is emerging for roles of miRNAs in modulating drug sensitivity/resistance of cells, 4,5 specifically for one class of miRNAs that target survival pathways or pathways that regulate apoptosis sensitivity, such ...

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