Knockdown of p54nrb inhibits migration, invasion and TNF-α release of human acute monocytic leukemia THP1 cells

Small molecule inhibition of RNA binding proteins in haematologic cancer

In recent years, advances in biomedicine have revealed an important role for post-transcriptional mechanisms of gene expression regulation in pathologic conditions. In cancer in general and leukaemia specifically, RNA binding proteins have emerged as important regulator of RNA homoeostasis that are often dysregulated in the disease state. Having established the importance of these pathogenetic mechanisms, there have been a number of efforts to target RNA binding proteins using oligonucleotide-based strategies, as well as with small organic molecules. The field is at an exciting inflection point with the convergence of biomedical knowledge, small molecule screening strategies and improved chemical methods for synthesis and construction of sophisticated small molecules. Here, we review the mechanisms of post-transcriptional gene regulation, specifically in leukaemia, current small-molecule based efforts to target RNA binding proteins, and future prospects.

NONO regulates multiple cytokine production in sepsis via the ERK1/2 signaling pathway

The massive release of pro-inflammatory cytokines is a crucial step in triggering the inflammatory cascade in sepsis. Exploring the key molecules regulating the expression and release of multiple cytokines has important value for revealing the mechanism of the cytokine storm in sepsis. This study aimed to investigate the role of multifunctional nuclear protein non-POU domain containing octamer-binding protein (NONO) in the sepsis cytokine storm and to elucidate the underlying mechanism. We found that NONO expression in tissues and cells of sepsis mice was significantly upregulated. Downregulation of NONO expression inhibited the mRNA expression of multiple cytokines, including IL-6, IL-1β, MCP-1, MIP-1α, and MIP-1β in inflammatory cells from mice and human leukemic monocyte-THP1 cells challenged with lipopolysaccharide (LPS), and significantly decreased the level of these cytokines and TNF-α in the supernatant of THP1 cells challenged by LPS. Nono knockout also reduced the levels of TNF-α, IL-6, MIP-1α, and MIP-1β in serum, alleviated hepatocyte edema, and improved the survival rate of sepsis mice. Reduced NONO expression decreased the phospho-ERK1/2 level in inflammatory cells from sepsis mice or THP1 cells challenged by LPS. Phospho-ERK1/2 inhibitor decreased the mRNA expression and concentration of cytokines in the culture supernatant of LPS-induced THP1 cells, similar to the effect of NONO knockdown. After LPS challenge, the levels of phospho-ERK1/2 and NONO were increased, with obvious colocalization in the nucleus and vesicular-like organelles in macrophages. NONO knockdown decreased nuclear translocation of phospho-ERK1/2 in LPS-challenged THP1 cells. These results suggest that NONO is a potentially critical molecule involved in multiple cytokine production in sepsis. Upregulated NONO in sepsis may promote the expression and release of multiple cytokines to participate in a sepsis cytokine storm by promoting ERK1/2 phosphorylation.

RNA-binding proteins as drivers of AML and novel therapeutic targets

Acute myeloid leukemia (AML) is a group of genetically complex and heterogeneous invasive hematological malignancies with a low 5-year overall survival rate of 30%, which highlights the urgent need for improved treatment measures. RNA-binding proteins (RBPs) regulate the abundance of isoforms of related proteins by regulating RNA splicing, translation, stability, and localization, thereby affecting cell differentiation and self-renewal. It is increasingly believed that RBPs are essential for normal hematopoiesis, and RBPs play a key role in hematological tumors, especially AML, by acting as oncogenes or tumor suppressors. In addition, targeting an RBP that is significantly related to AML can trigger the apoptosis of leukemic stem cells or promote the proliferation of stem and progenitor cells by modulating the expression of important pathway regulatory factors such as HOXA9, MYC, and CDKN1A. Accordingly, RBPs involved in normal myeloid differentiation and the occurrence of AML may represent promising therapeutic targets.

Knockout of the NONO Gene Inhibits Neointima Formation in a Mouse Model of Vascular Injury

[Figure: see text].

NONO and tumorigenesis: More than splicing

The non-POU domain-containing octamer-binding protein NONO/p54^nrb , which belongs to the Drosophila behaviour/human splicing (DBHS) family, is a multifunctional nuclear protein rarely functioning alone. Emerging solid evidences showed that NONO engages in almost every step of gene regulation, including but not limited to mRNA splicing, DNA unwinding, transcriptional regulation, nuclear retention of defective RNA and DNA repair. NONO is involved in many biological processes including cell proliferation, apoptosis, migration and DNA damage repair. Dysregulation of NONO has been found in many types of cancer. In this review, we summarize the current and fast-growing knowledge about the regulation of NONO, its biological function and implications in tumorigenesis and cancer progression. Overall, significant findings about the roles of NONO have been made, which might make NONO to be a new biomarker or/and a possible therapeutic target for cancers.

Increased Expression of microRNA-141-3p Improves Necrotizing Enterocolitis of Neonates Through Targeting MNX1

Objective: MicroRNA-141-3p (miR-141-3p) has been investigated in various kinds of cancers. This research delves into the functions and regulatory mechanisms of miR-141-3p in necrotizing enterocolitis (NEC) of neonates. Methods: NEC tissues were obtained from neonatal mice, and subsequently, expression of miR-141-3p and motor neuron and pancreas homeobox 1 (MNX1) was assayed via RT-qPCR. Moreover, the intestinal histopathological changes and histiocytic apoptosis were observed via hematoxylin and eosin (H&E) and TUNEL staining. The correlative inflammatory factors and oxidative stress markers were evaluated to uncover the influence of miR-141-3p in NEC tissue damage. Further, the relation between MNX1 and miR-141-3p was predicated, and the functions of MNX1 in inflammatory response and cell growth of IEC-6 cells were investigated. Results: Downregulated miR-141-3p and upregulated MNX1 were discovered in NEC tissues. Moreover, miR-141-3p clearly alleviated inflammation response and oxidative stress damage in NEC, which was achieved through regulating inflammatory cytokines (IL-1β, IL-6, and TNF-α) and oxidative stress markers (MPO, MDA, and SOD) expression. MNX1 was forecasted as a target gene of miR-141-3p; meanwhile, MNX1 overexpression overturned the influence of miR-141-3p in the inflammatory response and cell growth process of IEC-6 cells. Conclusion: These explorations reveal that increased expression of miR-141-3p could improve the damage to intestinal tissues in NEC through targeting MNX1. The research might exhibit a neoteric therapeutic strategy for NEC.

Targeted silencing of genes related to acute monocytic leukaemia by CpG(B)-MLAA-34 siRNA conjugates

Acute monocytic leukaemia (AML-M5) associated antigen-34 (MLAA-34) is a novel antigen overexpressed in patients with acute monocytic leukaemia. RNA interference is a promising therapy in oncology, especially for refractory acute leukaemia. In this study, we delivered MLAA-34 siRNA into AML-M5 THP-1 cells using CpG(B)-MLAA-34 siRNA conjugates, in the absence of any other transfection reagent. The uptake efficiency and the rate of apoptosis were measured by using flow cytometry. The level of relevant mRNAs was measured by quantitative PCR. THP-1 cell invasion was assessed by transwell assay. Protein expression was analysed by western blotting. The spleen and liver of AML-M5 nude mice were measured and weighted after euthanisation. Spleen sections were analysed by immunohistochemistry. We found that MLAA-34 siRNA was successfully delivered into THP-1 cells and induced MLAA-34 gene silencing via the blockade of JAK2/STAT3 and Wnt/-catenin signalling pathways. In addition, CpG(B)-MLAA-34 siRNA upregulated Gsk3β protein expression, resulting in retraining of the JAK2/STAT3 and Wnt/β-catenin signalling pathways. Importantly, CpG(B)-MLAA-34 siRNA reduced the survival and invasiveness of THP-1 cells. We further demonstrated that CAB39L was effectively downregulated by CpG(B)-MLAA-34 siRNA in vivo. These findings suggested CpG(B)-MLAA-34 siRNA conjugates may provide a novel therapeutic strategy for acute monocytic leukaemia.

Deficiency of NONO is associated with impaired cardiac function and fibrosis in mice

Non-POU-domain-containing octamer-binding protein (NONO), a component of multifunctional Drosophila behavior/human splicing (DBHS) family, plays an important role in regulating glucose and fat metabolism, circadian cycles, cell division, collagen formation and fibrosis. Dysfunctional variants of NONO have been described as the cause of congenital heart defects in males. However, the effects of NONO deficiency on the ventricular function and cardiac fibrosis as well as the related mechanisms are not clear. In the present study, we aimed to reveal the overall phenotypes, cardiac function and fibroblasts in NONO knockout (NONO KO) mice compared with the wild-type (WT) male littermates. The results showed that the birth rate of NONO^gt/0 mice was much lower than their WT male littermates at the time of weaning. The body weight of NONO^gt/0 mice was 19% lower than that of WT male littermates (27.2 ± 1.49 g vs. 22.01 ± 1.20 g, P < .001). NONO KO mice exhibited continuous higher mortality from birth to a year later (P < .05). Compared with those in the WT mice, the heart weight was lower(142.0 ± 8.7 mg vs. 179.0 ± 10.4 mg, P < .001), the heart weight to body weight ratio (HW/BW) was similar, the E/A ratio was higher (1.80 ± 0.47 vs. 1.44 ± 0.26, P < .05), and the left ventricular end diastolic diameter (LVEDd) was significantly lower (2.72 ± 0.51 mm vs.3.54 ± 0.43 mm, P < .001) in the NONO KO mice. We also found excessive matrix deposition in vivo. In vitro, NONO deficiency led to fibroblasts hyperproliferation, while migration was inhibited, which would induce collagen maturation and deposition. Conversely, overexpression of NONO inhibited fibroblasts proliferation and increased migration which reduced collagen deposition. RNA-seq of cardiac fibroblasts further indicated that NONO deficiency upregulated the cell cycle regulators, which included cyclin B2, the origin recognition complex 1 (ORC1) and cell division cycle 6 (CDC6), while downregulated the migration regulators, which included myosins, integrin and coagulation factor II. Overexpression of NONO further verified the effects of these indicators. In conclusion, our study demonstrated that NONO deficiency was associated with developing heart defects in mice. Hyperproliferation of cardiac fibroblasts with dramatically excessive collagen secretion might be the cause of heart defects of NONO KO mice.

Knockdown of TWIST enhances the cytotoxicity of chemotherapeutic drugs in doxorubicin-resistant HepG2 cells by suppressing MDR1 and EMT

The transcription factor twist family bHLH transcription factor 1 (TWIST), which is a member of the basic helix-loop-helix class of proteins, is known to induce epithelial-mesenchymal transition (EMT) and promote cancer metastasis. TWIST has previously been reported to be associated with multidrug resistance (MDR), since its depletion increases drug sensitivity. Although these previous studies have established a strong association between EMT and MDR, the molecular mechanism remains obscure. The present study demonstrated that TWIST protein expression was elevated in liver cancer, and was positively correlated with multidrug resistance protein 1 (MDR1) expression. Conversely, MDR1 was negatively correlated with E‑cadherin expression in liver cancer samples. In addition, the present study indicated that doxorubicin-resistant HepG2 (R‑HepG2) cells acquired an EMT phenotype. TWIST was also more highly expressed in R‑HepG2 cells compared with in parental HepG2 cells. Knockdown of TWIST increased the sensitivity of R‑HepG2 cells to 5-fluroracil, cisplatin and doxorubicin through a reduction in MDR1 expression and drug efflux ability. Furthermore, knockdown of TWIST in R‑HepG2 cells inhibited the migratory ability of cells and suppressed the EMT phenotype. These findings demonstrated that targeting TWIST may be considered a novel strategy to overcome drug resistance in liver cancer.