Downstream Axis Research Articles

M7G-modified mt-tRF3b-LeuTAA regulates mitophagy and metabolic reprogramming via SUMOylation of SIRT3 in chondrocytes

N7-methylguanosine (m7G) modification is one of the most prevalent RNA modifications, and methyltransferase-like protein-1 (METTL1) is a key component of the m7G methyltransferase complex. METTL1-catalyzed m7G as a new RNA modification pathway that regulates RNA structure, biogenesis, and cell migration. Increasing evidence indicates that m7G modification has been implicated in the pathophysiological process of osteoarthritis (OA). However, the underlying molecular mechanisms of m7G modification remains incompletely elucidated during the progression of OA. Here we found that METTL1 and m7G levels were markedly increased in OA chondrocytes. In addition, METTL1-mediated m7G modification upregulated mt-tRF3b-LeuTAA expression to exacerbate chondrocyte degeneration. Mechanistically, mt-tRF3b-LeuTAA decreased the SUMO-specific protease 1 (SENP1) protein expression and upregulated the level of sirtuin 3 (SIRT3) SUMOylation to inhibit PTEN induced kinase 1 (PINK1)/Parkin-mediated mitochondrial mitophagy. Intra-articular injection of PMC-tRF3b-LeuTAA inhibitor (Polyamidoamine-polyethylene glycol surface-modified with Minimal self-peptides and Chondrocyte-affinity peptides, PMC) attenuated destabilization of the medial meniscus (DMM) mouse cartilage degeneration in vivo. Our study demonstrates that METTL1/m7G/mt-tRF3b-LeuTAA axis accelerate cartilage degradation by inhibiting mitophagy and promoting mitochondrial dysfunction through SIRT3 SUMOylation, and suggest that targeting METTL1 and its downstream signaling axis could be a promising therapeutic target for OA treatment.

Kisspeptin in functional hypothalamic amenorrhea: Pathophysiology and therapeutic potential.

Functional hypothalamic amenorrhea (FHA) is one of the most common causes of secondary amenorrhea, resulting in anovulation and infertility, and is a low estrogen state that increases the risk of cardiovascular disease and impairs bone health. FHA is characterized by acquired suppression of physiological pulsatile gonadotropin-releasing hormone (GnRH) release by the hypothalamus in the absence of an identifiable structural cause, resulting in a functional hypogonadotropic hypogonadism. FHA results from either decreased energy intake and/or excessive exercise, leading to low energy availability and weight loss-often in combination with psychological stress on top of a background of genetic susceptibility. The hypothalamic neuropeptide kisspeptin is a key component of the GnRH pulse generator, tightly regulating pulsatile GnRH secretion and the downstream reproductive axis. Here, we review the physiological regulation of pulsatile GnRH secretion by hypothalamic kisspeptin neurons and how their activity is modulated by signals of energy status to affect reproductive function. We explore endocrine factors contributing to the suppression of GnRH pulsatility in the pathophysiology of FHA and how hypothalamic kisspeptin neurons likely represent a final common pathway through which these factors affect GnRH pulse generation. Finally, we discuss the therapeutic potential of kisspeptin as a novel treatment for women with FHA.

Novel insights into the GCN2 pathway and its targeting. Therapeutic value in cancer and lessons from lung fibrosis development.

Defining the mechanisms that allow cells to adapt to environmental stress is critical for understanding the progression of chronic diseases and identifying relevant drug targets. Among these, activation of the pathway controlled by the eIF2-alpha kinase GCN2 is critical for translational and metabolic reprogramming of the cell in response to various metabolic, proteotoxic, and ribosomal stressors. However, its role has frequently been investigated through the lens of a stress pathway signaling via the eIF2α-activating transcription factor 4 (ATF4) downstream axis, while recent advances in the field have revealed that the GCN2 pathway is more complex than previously thought. Indeed, this kinase can be activated through a variety of mechanisms, phosphorylate substrates other than eIF2α, and regulate cell proliferation in a steady state. This review presents recent findings regarding the fundamental mechanisms underlying GCN2 signaling and function, as well as the development of drugs that modulate its activity. Furthermore, by comparing the literature on GCN2's antagonistic roles in two challenging pathologies, cancer and pulmonary diseases, the benefits, and drawbacks of GCN2 targeting, particularly inhibition, are discussed.

DUSP22 inhibits lung tumorigenesis by suppression of EGFR/c-Met signaling

DUSP22, an atypical dual-specificity phosphatase enzyme, plays a significant role in regulating multiple kinase signaling pathways by dephosphorylation. Our study demonstrated that decreased DUSP22 expression is associated with shorter disease-free survival, advanced TNM (tumor, lymph nodes, and metastasis), cancer stage, and higher tumor grade in lung adenocarcinoma (LUAD) patients. Exogenous DUSP22 expression reduces the colony-forming capacity of lung cancer cells and inhibits xenograft tumor growth primarily by targeting EGFR and suppressing its activity through dephosphorylation. Knockdown of DUSP22 using shRNA enhances EGFR dependency in HCC827 lung cancer cells and increases sensitivity to gefitinib, an EGFR inhibitor. Consistently, genetic deletion of DUSP22 enhances EGFRdel (exon 19 deletion)-driven lung tumorigenesis and elevates EGFR activity. Pharmacological inhibition of DUSP22 activates EGFR, ERK1/2, and upregulates downstream PD-L1 expression. Additionally, lentiviral deletion of DUSP22 by shRNA enhances lung cancer cell migration through EGFR/c-Met and PD-L1-dependent pathways. Gefitinib, an EGFR inhibitor, mechanistically suppresses migration induced by DUSP22 deletion and inhibits c-Met activity. Furthermore, cabozantinib, a c-Met inhibitor, reduces migration and attenuates EGFR activation caused by DUSP22 deletion. Collectively, our findings support the hypothesis that loss of DUSP22 function in lung cancer cells confers a survival advantage by augmenting EGFR signaling, leading to increased activation of downstream c-Met, ERK1/2, and PD-L1 axis, ultimately contributing to the progression of advanced lung cancer.

Inflammatory response in traumatic brain and spinal cord injury: The role of XCL1-XCR1 axis and T cells.

Traumatic brain injury (TBI) and spinal cord injury (SCI) are acquired injuries to the central nervous system (CNS) caused by external forces that cause temporary or permanent sensory and motor impairments and the potential for long-term disability or even death. These conditions currently lack effective treatments and impose substantial physical, social, and economic burdens on millions of people and families worldwide. TBI and SCI involve intricate pathological mechanisms, and the inflammatory response contributes significantly to secondary injury in TBI and SCI. It plays a crucial role in prolonging the post-CNS trauma period and becomes a focal point for a potential therapeutic intervention. Previous research on the inflammatory response has traditionally concentrated on glial cells, such as astrocytes and microglia. However, increasing evidence highlights the crucial involvement of lymphocytes in the inflammatory response to CNS injury, particularly CD8+ T cells and NK cells, along with their downstream XCL1-XCR1 axis. This review aims to provide an overview of the role of the XCL1-XCR1 axis and the T-cell response in inflammation caused by TBI and SCI and identify potential targets for therapy. We conducted a comprehensive search of PubMed and Web of Science using relevant keywords related to the XCL1-XCR1 axis, T-cell response, TBI, and SCI. This study examines the upstream and downstream pathways involved in inflammation caused by TBI and SCI, including interleukin-15 (IL-15), interleukin-12 (IL-12), CD8+ T cells, CD4+ T cells, NK cells, XCL1, XCR1+ dendritic cells, interferon-gamma (IFN-γ), helper T0 cells (Th0 cells), helper T1 cells (Th1 cells), and helper T17 cells (Th17 cells). We describe their proinflammatory effect in TBI and SCI. The findings suggest that the XCL1-XCR1 axis and the T-cell response have great potential for preclinical investigations and treatments for TBI and SCI.

NLRX1 Inhibits LPS-Induced Microglial Death via Inducing p62-Dependent HO-1 Expression, Inhibiting MLKL and Activating PARP-1.

The activation of microglia and the production of cytokines are key factors contributing to progressive neurodegeneration. Despite the well-recognized neuronal programmed cell death regulated by microglial activation, the death of microglia themselves is less investigated. Nucleotide-binding oligomerization domain, leucine-rich repeat-containing X1 (NLRX1) functions as a scaffolding protein and is involved in various central nervous system diseases. In this study, we used the SM826 microglial cells to understand the role of NLRX1 in lipopolysaccharide (LPS)-induced cell death. We found LPS-induced cell death is blocked by necrostatin-1 and zVAD. Meanwhile, LPS can activate poly (ADP-ribose) polymerase-1 (PARP-1) to reduce DNA damage and induce heme oxygenase (HO)-1 expression to counteract cell death. NLRX1 silencing and PARP-1 inhibition by olaparib enhance LPS-induced SM826 microglial cell death in an additive manner. Less PARylation and higher DNA damage are observed in NLRX1-silencing cells. Moreover, LPS-induced HO-1 gene and protein expression through the p62-Keap1-Nrf2 axis are attenuated by NLRX1 silencing. In addition, the Nrf2-mediated positive feedback regulation of p62 is accordingly reduced by NLRX1 silencing. Of note, NLRX1 silencing does not affect LPS-induced cellular reactive oxygen species (ROS) production but increases mixed lineage kinase domain-like pseudokinase (MLKL) activation and cell necroptosis. In addition, NLRX1 silencing blocks bafilomycin A1-induced PARP-1 activation. Taken together, for the first time, we demonstrate the role of NLRX1 in protecting microglia from LPS-induced cell death. The underlying protective mechanisms of NLRX1 include upregulating LPS-induced HO-1 expression via Nrf2-dependent p62 expression and downstream Keap1-Nrf2 axis, mediating PARP-1 activation for DNA repair via ROS- and autophagy-independent pathway, and reducing MLKL activation.

The Natural Product Secoemestrin C Inhibits Colorectal Cancer Stem Cells via p38-S100A8 Feed-Forward Regulatory Loop.

Cancer stem cells (CSCs) are closely associated with tumor initiation, metastasis, chemoresistance, and recurrence, which represent some of the primary obstacles to cancer treatment. Targeting CSCs has become an important therapeutic approach to cancer care. Secoemestrin C (Sec C) is a natural compound with strong anti-tumor activity and low toxicity. Here, we report that Sec C effectively inhibited colorectal CSCs and non-CSCs concurrently, mainly by inhibiting proliferation, self-renewal, metastasis, and drug resistance. Mechanistically, RNA-seq analysis showed that the pro-inflammation pathway of the IL17 axis was enriched, and its effector S100A8 was dramatically decreased in Sec C-treated cells, whose roles in the stemness of CSCs have not been fully clarified. We found that the overexpression of S100A8 hindered the anti-CSCs effect of Sec C, and S100A8 deficiency attenuated the stemness traits of CSCs to enhance the Sec C killing activity on them. Meanwhile, the p38 signal pathway, belonging to the IL17 downstream axis, can also mediate CSCs and counter with Sec C. Notably, we found that S100A8 upregulation increased the p38 protein level, and p38, in turn, promoted S100A8 expression. This indicated that p38 may have a mutual feedback loop with S100A8. Our study discovered that Sec C was a powerful anti-colorectal CSC agent, and that the positive feedback loop of p38-S100A8 mediated Sec C activity. This showed that Sec C could act as a promising clinical candidate in colorectal cancer treatment, and S100A8 could be a prospective drug target.

Identification of a hypoxia-suppressed lncRNA RAMP2-AS1 in breast cancer

Hypoxia is a critical feature of solid tumors and exerts crucial roles in cancers, including breast cancer. However, the detailed relationship between lncRNA-miRNA-mRNA triple network and hypoxia in breast cancer is still indistinct. In this study, a series of in silico analyses and online databases or tools were employed to establish a hypoxia-related lncRNA-miRNA-mRNA network in breast cancer based on competing endogenous RNA mechanism at single-cell resolution. RAMP2-AS1 was, eventually, identified as the most potential lncRNA, which was significantly negatively associated with hypoxia in breast cancer. Compared with normal controls, RAMP2-AS1 was markedly downregulated in breast cancer. Moreover, survival analysis revealed favorable prognostic values of RAMP2-AS1 in total or in specific clinicopathological breast cancer patients. Next, miR-660-5p, miR-2277-5p and miR-1301-3p, upregulated and possessed poor prognostic values in breast cancer, were identified as three potential downstream miRNAs of RAMP2-AS1. Then, the most potential downstream hypoxia-related genes (ATM and MYH11) of RAMP2-AS1/miRNA axis in breast cancer were screened out. Intriguingly, in vitro experiments confirmed that RAMP2-AS1 was a hypoxia-suppressed lncRNA and miR-660-5p/ATM was a potential downstream axis of RAMP2-AS1 in breast cancer. Collectively, our current data elucidated a key hypoxia-suppressed lncRNA RAMP2-AS1 and its possible miRNA-mRNA regulatory mechanism in breast cancer.

Effect of fluid elasticity and shear thinning on heat transfer from a heated sphere at moderate Reynolds numbers

The drag and heat transfer characteristics of an isothermal sphere in a FENE-P-type viscoelastic fluid have been studied in the steady axisymmetric flow regime. The governing equations, namely, mass, momentum, and energy equations, together with FENE-P type viscoelastic constitutive equations, have been solved using the finite volume method based opensource CFD code OpenFOAM over the following ranges of conditions: Reynolds number, 1 ≤ Re ≤ 100 ; Prandtl number, 1 ≤ Pr ≤ 50 ; Weissenberg number, 0 ​ ≤ Wi ≤ 10 and polymer extensibility parameter, 10 ≤ L 2 ≤ 500 for a fixed value of the polymer viscosity ratio of β = 0.5 . At low Reynolds numbers, fluid viscoelasticity causes an upward and downward shifting in the axial velocity profiles with reference to that in a Newtonian fluid along the upstream and downstream axis of the sphere, respectively. However, such a shift progressively diminishes with the increasing Reynolds number. Furthermore, a “velocity overshoot” and/or a “negative wake” is also observed in a viscoelastic polymer solution at low Reynolds numbers, and this is accentuated with the increasing Weissenberg number. The separation of boundary layers is seen to be suppressed with the increasing Weissenberg number. The drag coefficient decreases with the Reynolds number irrespective of the fluid type and the corresponding dependence on the Weissenberg number is found to be non-monotonic depending upon the values of Re and L 2. The average Nusselt number always increases with the increasing values of Re, Pr, and Wi and with the decreasing value of L 2. A limited number of simulations have also been carried out to show the effect of the temperature-dependent viscosity of the fluid on the flow dynamics and heat transfer characteristics. Finally, simple correlations for the drag coefficient and average Nusselt number are presented which not only capture the functional dependence but also can be used for the interpolation of the present results for the intermediate values of the governing parameters in a new application.

The role of PKC and PKD in CXCL12 and CXCL13 directed malignant melanoma and acute monocytic leukemic cancer cell migration.

Cancer metastasis is the leading cause of cancer related mortality. Chemokine receptors and proteins in their downstream signalling axis represent desirable therapeutic targets for the prevention of metastasis. Despite this, current therapeutics have experienced limited success in clinical trials due to a lack of insight into the downstream signalling pathway of specific chemokine receptor cascades in different tumours. In this study, we investigated the role of protein kinase C (PKC) and protein kinase D (PKD) in CXCL12 and CXCL13 stimulated SK-MEL-28 (malignant melanoma) and THP-1 (acute monocytic leukaemia) cell migration. While PKC and PKD had no active role in CXCL12 or CXCL13 stimulated THP-1 cell migration, PKC and PKD inhibition reduced CXCL12 stimulated migration and caused profound effects upon the cytoskeleton of SK-MEL-28 cells. Furthermore, only PKC and not PKD inhibition reduced CXCL13 stimulated migration in SK-MEL-28 cells however PKC inhibition failed to stimulate any changes to the actin cytoskeleton. These findings indicate that PKC inhibitors would be a useful therapeutic for the prevention of both CXCL12 and CXCL13 stimulated migration and PKD inhibitors for CXCL12 stimulated migration in malignant melanoma.

Shallow current of viscous fluid flowing between diverging or converging walls

We investigate the shallow flow of viscous fluid into and out of a channel whose gap width increases as a power law ( $x^n$ ), where $x$ is the downstream axis. The fluid flows slowly, while injected at a rate in the form of $t^\alpha$ , where $t$ is time and $\alpha$ is a constant. The invading fluid has a higher viscosity than the ambient fluid, thus avoiding Saffman–Taylor instability. Similarity solutions of the first kind for the outflow problem are found using approximations of lubrication theory. Zheng et al. (J. Fluid Mech., vol. 747, 2014, pp. 218–246) studied the deep-channel case and found divergent behaviour of the similarity variable as $n\rightarrow 1$ and $n\rightarrow 3$ , when fluid flows into and out of the channel, respectively. No divergence is found in the shallow case presented here up to the breakdown of the geometric assumption. The characteristic equilibration time for the numerically simulated constant-volume flow to converge to the similarity solution is calculated assuming an inverse dependence on the ratio disagreement between the current front using the method of lines. An inverse power dependence between equilibration time and ratio disagreement is found for channels of different powers. A similarity solution of the second kind for the inflow problem is found using the phase-plane formalism and the bisection method. An exponential decay relationship is found between $n$ and the degree $\delta$ of the similarity variable $xt^{-\delta }$ , which does not show any divergent behaviour for large $n$ . An asymptotic behaviour is found for $\delta$ that approaches $1/2$ for $n\gg 1$ .

Inclination Trend of the Agulhas Return Current Path in Three Decades

The Agulhas Return Current (ARC), as a primary component of the Agulhas system, contributes to water exchange and mass transport between the southern portions of the Indian and Atlantic Ocean basins. In this study, satellite altimeter data and reanalysis datasets, and a new set of criteria for the piecewise definition of the jet axis are used to explore the long-term change of the ARC’s axis position in recent three decades. It is found that the ARC axis exhibits a significant slanting trend with its western part (35–48°E) migrating northward and the eastern part (48–70°E) migrating southward. The meridional movement of the ARC path could be attributed to large-scale wind forcing. The anomalous surface wind stress curl, by Ekman pumping mechanism, leads to positive–negative–positive sea surface height anomalies in the western section and negative–positive–negative anomalies in the eastern section, thus the ARC axis tilts accordingly, in a northwest–southeast direction. Further analysis suggests that this ARC slanting trend is more dependent on the southward shift of the downstream axis and less on the topographic steering upstream. The downstream axis is more likely to interact with the ACC fronts and its migration could dominate the local EKE pattern by changing the background circulation and energy cascade direction. For the headstream west of 35°E, the ARC axis is more subject to topography, thus the EKE change is more dominated by eddy activity processes, including shedding, propagation and merging. This study provides some new insights into the long-term change of ARC and its interaction with the local EKE variability.

Erythropoietin Suppresses the Hepatic Fibrosis Caused by Thioacetamide: Role of the PI3K/Akt and TLR4 Signaling Pathways.

Erythropoietin (EPO) is recognized for its function in erythropoiesis; however, its potential antifibrotic effect against liver fibrosis remains unknown. This study examined whether EPO affects thioacetamide (TAA)-induced liver fibrosis by concentrating on the Toll-like receptor 4 (TLR4) cascade and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway as possible pathways. Male Wistar rats were randomized into four groups, which included: the negative control group, the TAA group (intraperitoneal; TAA 100 mg/kg three times per week for 2 weeks), and EPO-treated groups (150 and 300 IU/kg, i.p.) for 2 weeks after TAA injections. EPO attenuated hepatic fibrosis in a dosage-dependent way, as manifested by the diminution in serum alanine aminotransferase and aspartate aminotransferase activities, as well as the increase in albumin level. EPO inhibited the increase in tissue levels of tumor necrosis factors-α, interleukin-1β, transforming growth factor-β1, and TLR4 and raised tissue levels of PI3K and p-PI3K. EPO antioxidant properties were demonstrated by restoring hepatic glutathione and superoxide dismutase by preventing the accumulation of hepatic malondialdehyde. Further, EPO increased the protein expression of PI3K and Akt and decreased TLR4 protein expression. Immunohistochemically, EPO treatment altered tissue histology and downregulated mitogen-activated protein kinase protein expression. Overall, the research suggested that EPO could prevent TAA-induced hepatic fibrosis through upregulating the PI3K/Akt signaling cascade and downregulation the TLR4 downstream axis.

E2F2 serves as an essential prognostic biomarker and therapeutic target for human renal cell carcinoma by presenting “E2F2/miR-16–5p/SPTLC1” schema

BackgroundRenal cell carcinoma (RCC) is a common malignant tumor of the urinary system with high mortality and morbidity. Although E2F2, a classical transcription factor implicated in cell cycle, has been shown to foster tumorigenesis in several human cancers, it could not draw a satisfy answer referring to precise downstream signaling axis in RCC development yet. MethodsBased on the publicly available data from TCGA database, expression patterns of E2F2, SPTLC1 and miR-16–5p were identified, either with the ability to predict the prognosis of patients with RCC, which was further validated in 38 paired RCC tissues and matched adjacent tissues by RT-qPCR and Western blot, respectively. Their cellular biofunctions were evaluated using MTT, EdU, Colony formation and transwell assays. Chromatin immunoprecipitation (ChIP) and luciferase reporter assay were employed to certain the exquisite core transcription regulatory circuitry of E2F2/miR-16–5p/SPTLC1 in RCC progression, which was also determined in xenograft tumor model. ResultsConsistent with the public TCGA database, E2F2 was significantly increased in RCC tissues and cells, indicating shorter overall survival. Mechanistically, E2F2 served as a transcriptional activator of miR-16–5p, thus accounting for its negative regulation on SPTLC1 expression. E2F2 knockdown-mediated suppressive biofunctions on RCC cells were rescued by miR-16–5p mimics, while this effect was abolished again by SPTLC1 overexpression. Role of E2F2 on RCC tumorigenesis via the miR-16–5p/SPTLC1 axis was verified both in vitro and in vivo. ConclusionE2F2 promoted RCC progression via the miR-16–5p/SPTLC1 axis, which may represent a novel prognostic and therapeutic biomarker for RCC.

Internal ring waves in a three-layer fluid on a current with a constant vertical shear

Oceanic internal waves often have curvilinear fronts and propagate over vertically sheared currents. We present the first study of long weakly-nonlinear internal ring waves in a three-layer fluid in the presence of a horizontally uniform background current with a constant vertical shear. The leading order of this theory leads to the angular adjustment equation—a nonlinear first-order ordinary differential equation describing the dependence of the linear long-wave speed on its angle to the direction of the current. The compact ring waves, well studied in the absence of a current, correspond to the singular solution (envelope of the general solution) of this equation, and they can exist only under certain conditions. The constructed solutions reveal qualitative differences in the shapes of the wavefronts of the two baroclinic modes: the wavefront of the faster mode is elongated in the direction of the current, while the wavefront of the slower mode is squeezed. Moreover, depending on the vorticity strength, several different regimes have been identified. When the vertical shear is weak, part of the wavefront is able to propagate upstream, while when the shear is strong enough, the whole wavefront propagates downstream. A richer pattern of behaviour is observed for the slower mode. As the shear increases, singularities of the swallowtail-type may arise and, eventually, solutions with compact wavefronts crossing the downstream axis cease to exist. We show that the latter is related to the long-wave instability of the base flow. We obtain the cKdV-type amplitude equation and examine analytical expressions for its coefficients. Using this cKdV-type equation we numerically model the evolution of the waves for both modes. The initial stage of the evolution is in agreement with the leading-order predictions for the deformations of the wavefronts. Then, as the wavefronts expand, strong dispersive effects occur in the upstream direction. Moreover, when nonlinearity is enhanced, fission of waves is observed in the upstream part of the ring waves.

Abstract 3936: ALK fusion oncogene driven SERPINB4 expression enhances tumor survival in NSCLC

Abstract Anaplastic lymphoma kinase (ALK) fusion variants in non-small-cell-lung cancer (NSCLC) consist of numerous dimerising fusion partners, with the most common being EML4. Clinical data suggests that the degree of treatment benefit in response to ALK tyrosine kinase inhibitors (TKIs) differs among the variant present in the patient tumor. Therefore, a better understanding the oncogenic signaling networks driven by different ALK-fusion variants is important. Here, we developed highly controlled doxycycline-inducible cell models bearing four different ALK fusion proteins, namely EML4-ALK-V1, EML4-ALK-V3, KIF5B-ALK, and TFG-ALK, in the context of non-tumorigenic NL20 human bronchial epithelial cells. These were complimented by patient-derived NSCLC cell lines harboring either EML4-ALK-V1 or EML4-ALK-V3 fusions. RNA-seq and phosphoproteomics analysis were employed to identify dysregulated genes and hyper/hypo-phosphorylated proteins associated with ALK fusion expression. Among ALK fusion induced responses, we noted a robust inflammatory signature that included up-regulation of the Serpin B4 serine protease inhibitor in both NL20-inducible cell models and ALK-positive NSCLC patient-derived cell lines. We show that STAT3 is a major transcriptional regulator of SERPINB4 downstream of ALK fusions, along with NF-kB and AP1. The upregulation of SERPINB4 promotes survival of ALK fusion expressing cells and inhibits natural killer (NK) cell-mediated cytotoxicity. In conclusion, our study reveals a novel ALK downstream survival axis that regulates Serpin B4 expression and identifies a molecular target that has potential for therapeutic impact targeting the immune response together with ALK TKIs in NSCLC. Citation Format: Tzu-Po Chuang, Wei-Yun Lai, Jonatan L. Gabre, Dan E. Lind, Ganesh Umapathy, Abdulmalik A. Bokhari, Bengt Bergman, Linnea Kristenson, Fredrik B. Thorén, Anh Le, Robert Doebele, Jimmy V. Eynden, Ruth H. Palmer, Bengt Hallberg. ALK fusion oncogene driven SERPINB4 expression enhances tumor survival in NSCLC. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3936.

Circular RNA 0001789 sponges miR-140-3p and regulates PAK2 to promote the progression of gastric cancer

BackgroundGastric cancer (GC) is the third-leading cause of cancer-associated mortalities globally. The deregulation of circular RNAs (circRNAs) and microRNAs (miRNAs or miRs) is widely implicated in the pathogenesis and progression of different cancer types.MethodsThe expression profiling of circRNAs in GC is required to identify crucial circRNAs as biomarkers or therapeutic targets. In the present study, a published circRNA microarray dataset was used to identify differentially expressed circRNAs between GC tissues and normal gastric mucosa tissues. Reverse transcription-quantitative PCR was performed to validate the expression of circ_0001789. Fisher’s exact test, receiver operating characteristic curve and Kaplan-Meier plots were employed to analyze the clinical significance of circ_0001789. The miRNA targets of circ_0001789 were predicted using an online database, and their functional interaction was further confirmed by RNA pull-down, RNA immunoprecipitation and dual luciferase reporter assays. Transwell assays were conducted to investigate the biological functions of circ_0001789, miR-140-3p and p21 activated kinase 2 (PAK2) in the migration and invasion of GC cells. A xenograft mouse model was established to validate the role of circ_0001789 in the tumorigenesis of GC cells.Resultscirc_0001789 was identified as a highly expressed circRNA in GC tissues versus normal gastric mucosa tissues. Silencing circ_0001789 attenuated the malignancy of GC cells, and exosomal circ_0001789 was sufficient to regulate the malignant phenotype of GC cells. miR-140-3p was further identified as a downstream target of circ_0001789, which showed a negative correlation with circ_0001789 expression in GC tissues. Overexpression of miR-140-3p suppressed cell migration, invasion and epithelial-mesenchymal transition in GC cells. PAK2 was identified as the target of miR-140-3 to mediate the malignant phenotype of GC cells.ConclusionThe present data suggested that the upregulation of circ_0001789 was associated with the progression of GC and with poor prognosis in patients with GC, and that miR-140-3p/PAK2 served as the downstream axis to mediate the oncogenic effect of circ_0001789.

ZFX-mediated upregulation of CEBPA-AS1 contributes to acute myeloid leukemia progression through miR-24-3p/CTBP2 axis.

Emerging reports demonstrated that long non-coding RNAs (lncRNAs) play a role in the pathogenesis and metastasis of cancers. However, the biological functions and underlying mechanisms of LncRNA CEBPA-AS1 in acute myeloid leukemia (AML) remain largely elusive. The level of CEBPA-AS1 was examined in AML clinical tissues and cell lines via fluorescence in situ hybridization (FISH) and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In vivo and in vitro functional tests were applied to identify the pro-oncogenic role of CEBPA-AS1 in AML development. The overexpressed CEBPA-AS1 was linked to poor survival in AML patients. Moreover, the relationships among CEBPA-AS1, Zinc Finger Protein X-Linked (ZFX), and miR-24-3p were predicted by bioinformatics and validated by RNA immunoprecipitation (RIP) and luciferase reporter assays. Our findings unveiled that transcription factor ZFX particularly interacted with the promoter of CEBPA-AS1 and activated CEBPA-AS1 transcription. Downregulation of CEBPA-AS1 inhibited the proliferation and invasion while promoted apoptosis of AML cells in in vitro, as well as in vivo, xenograft tumor growth was modified. However, overexpression of CEBPA-AS1 observed the opposite effects. Furthermore, CEBPA-AS1 acted as a competitive endogenous RNA (ceRNA) of miR-24-3p to attenuate the repressive effects of miR-24-3p on its downstream target CTBP2. Taken together, this study emphasized the pro-oncogenic role of CEBPA-AS1 in AML and illustrated its connections with the upstream transcription factor ZFX and the downstream regulative axis miR-24-3p/CTBP2, providing important insights to the cancerogenic process in AML.

Longitudinal patterns of fish assemblages in relation to environmental factors in the Anning River, China

In order to explore the spatial layout of fish assemblages and their related environmental factors, a survey of species composition was conducted in the Anning River. From 2018 to 2021, 28 sites at 987–2,077 m in altitude were surveyed, gathering 64 species in total, of which 60 were native and 4 were exotic. Fifteen of the species sampled were indigenous to the upper Yangtze River, and two were classified as critically endangered or endangered. Fish communities displayed significant upstream-to-downstream variation. There are two site-groups, one covering upstream and tributaries and the other covering midstream and downstream. The upstream-tributary fish assemblages had a dominance of Nemacheilidae and Schizothoracinae, which are plateau species with habitat preferences for boulders and fast-flowing water. Conversely, the mid-downstream fish assemblages had a dominance of Gobioninae, Cyprininae, Bagridae and Siluridae, which are common river species that prefer slow-flowing water. The spatial patterns of these fish communities were chiefly affected by altitude and substratum composition. The fish assemblage pattern was consistent with the zonation concept because the fish communities changed abruptly and clearly along the upstream–downstream axis. The findings of this study offer a crucial research foundation for comprehending the fish assemblages of mountainous rivers, which will be conducive to biodiversity management and habitat preservation of aquatic species.

Implicative role of epidermal growth factor receptor and its associated signaling partners in the pathogenesis of Alzheimer's disease.

Epidermal growth factor receptor (EGFR) plays a pivotal role in early brain development, although its expression pattern declines in accordance with the maturation of the active nervous system. However, recurrence of EGFR expression in brain cells takes place during neural functioning decline and brain atrophy in order to maintain the homeostatic neuronal pool. As a consequence, neurotoxic lesions such as amyloid beta fragment (Aβ1-42) formed during the alternative splicing of amyloid precursor protein in Alzheimer's disease (AD) elevate the expression of EGFR. This inappropriate peptide deposition on EGFR results in the sustained phosphorylation of the downstream signaling axis, leading to extensive Aβ1-42 production and tau phosphorylation as subsequent pathogenesis. Recent reports convey that the pathophysiology of AD is correlated with EGFR and its associated membrane receptor complex molecules. One such family of molecules is the annexin superfamily, which has synergistic relationships with EGFR and is known for membrane-bound signaling that contributes to a variety of inflammatory responses. Besides, Galectin-3, tissue-type activated plasminogen activator, and many more, which lineate the secretion of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-18) result in severe neuronal loss. Altogether, we emphasized the perspectives of cellular senescence up-regulated by EGFR and its associated membrane receptor molecules in the pathogenesis of AD as a target for a therapeutical alternative to intervene in AD.