Neutrophil elastase enhances the proliferation and decreases apoptosis of leukemia cells via activation of PI3K/Akt signaling

p110CUX1 promotes acute myeloid leukemia progression via regulating pyridoxal phosphatase expression and activating PI3K/AKT/mTOR signaling pathway

As an evolutionarily conserved transcription factor, Cut-like homeobox 1 (CUX1) plays crucial roles in embryonic and nervous system development, cell differentiation, and DNA damage repair. One of its major isoforms, p110CUX1, exhibits stable DNA binding capabilities and contributes to the regulation of cell cycle progression, proliferation, migration, and invasion. While p110CUX1 has been implicated in the progression of various malignant tumors, its involvement in acute myeloid leukemia (AML) remains uncertain. This study aims to elucidate the role of p110CUX1 in AML. Our findings reveal heightened expression levels of both p110CUX1 and pyridoxal phosphatase (PDXP) in AML cell lines. Overexpression of p110CUX1 promotes AML cell proliferation while inhibiting apoptosis and differentiation, whereas knockdown of PDXP yields contrasting effects. Mechanistically, p110CUX1 appears to facilitate AML development by upregulating PDXP expression and activating the PI3K/AKT/mTOR signaling pathway. Animal experimental corroborate the pro-AML effect of p110CUX1. These results provide experimental evidence supporting the involvement of the p110CUX1-PDXP-PI3K/AKT/mTOR axis in AML progression. Hence, targeting p110CUX1 may hold promise as a therapeutic strategy for AML.

3D DNAzyme Motor Nanodevice With Self-Powered FRET Amplifier and Self-Supplied H2O2 for Enhancing Human Neutrophil Elastase Profiling and Chemodynamic Therapy in Lung Tumor

The development of theragnostic nanosystems integrating FRET (fluorescence resonance energy transfer) imaging and chemodynamic therapy (CDT) for accurate diagnosis and effective treatment of lung tumors is still a big challenge. Herein, a peptide-assembled 3D DNAzyme motor nanodevice is engineered for a self-powered FRET amplifier profiling human neutrophil elastase (HNE) and self-supplied H2O2 enhancing CDT. The nanodevice is prepared by depositing AuNPs on ZIF-8, in which ZIF-8 co-loaded the lysosomal targeting peptide-modified copper peroxides (PCPs) and hairpins (H1, H2, and H3), AuNPs are co-labeled by DNAzyme-peptide (DP) conjugate and H3. In the tumor micro-environment, HNE driven 3D DNAzyme walker followed by an exponential amplification constructed by a synergistic cross-activation between hybridization chain reaction and DNAzyme, generating a self-powered FRET amplifier. The FRET amplifier specifically measures HNE with a sensitivity of 0.026 pM, and successfully images exogenous HNE in living cells and monitors HNE in mouse models. Moreover, the PCPs can target lysosomes, reducing lysosome escape. The self-supplying H2O2 undertaken by PCPs improves the Cu (II)-catalyzed Fenton-like reaction, effectively causing cell apoptosis to inhibit tumor growth. Significantly, the nanodevice successfully screens inhibitors and discriminates the HNE level in normal and lung cancer tissues, suggesting that the nanodevice provides an effective tool for the diagnosis and treatment of lung tumors.

ELANE is a promising prognostic biomarker that mediates pyroptosis in gastric cancer

Background

Gastric cancer (GC) is a typical malignant tumor and the main cause of cancer-related deaths. Its pathogenesis involves multiple steps, including pyroptosis, although these steps are still uncertain. Pyroptosis, also known as gasdermin-mediated programmed necrosis, participates in various pathological processes in tumors, including GC. ELANE, which encodes neutrophil elastase, is closely associated with GC. Additionally, ELANE has been implicated in GC cell pyroptosis, but this has not been confirmed. Therefore, investigating the link between ELANE and pyroptosis in GC is warranted. This research uses bioinformatics and experiments to examine the relationship between ELANE, pyroptosis, and GC prognosis.

Methods

The GEO and TCGA databases, along with pyroptosis-related genes, were applied to identify pyroptosis-related differentially expressed genes (DEGs). ELANE was selected via primary screening. Using the median expression level of ELANE as the threshold, pyroptosis-related DEGs were divided into low- and high-ELANE groups. Based on the DEGs in these two groups, GO, KEGG and GSEA analyses were conducted to elucidate the mechanisms of ELANE in GC. Furthermore, we plotted ROC and Kaplan-Meier curves to analyze the clinical and pathological features of ELANE expression. The Nomograms tool was applied to calculate the predictive value of ELANE for the clinical outcomes of GC cases. Immunohistochemical analysis was performed to detect the level of ELANE in GC tissues and to validate whether ELANE was involved in pyroptosis in GC cells through cell experiments. Finally, the immune infiltration of ELANE was investigated, and interaction networks (proteins-ELANE, microRNA-ELANE, and small-molecule drug-ELANE) were constructed.

Results

We aimed to investigate the expression of the ELANE gene in GC and study the relationship among ELANE, pyroptosis, and the prognosis of patients with GC. Differential expression analysis of gene-expression datasets from TCGA-STAD and GSE49051 revealed that the expression of the ELANE gene was significantly up-regulated in GC. Using STRING network analysis, we identified multiple proteins involved in the occurrence and development of GC, including interactions between ELANE and GSDMC, a member of the gasdermin protein family. Survival analysis showed that ELANE expression levels significantly affected overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS) in patients with GC. Additionally, ROC analysis demonstrated that ELANE was effective in distinguishing GC patients from normal controls (AUC = 0.812). Immunohistochemical analysis showed that ELANE was highly expressed in gastric cancer tissues and was closely related to age, tumor grade, and stage. The cell experiments further confirmed that the high expression of ELANE in gastric cancer cells was associated with pyroptosis. Comprehensive analysis indicated that ELANE could be used as a potential prognostic marker for GC and plays an important role in pyroptosis.

Conclusion

High ELANE expression is related to poor survival and prognosis of patients with GC. It participates in pyroptosis and immune infiltration in GC. Therefore, ELANE is a promising prognostic biomarker for pyroptosis in GC.

Prognostic value of lung immune prognostic index in non-small cell lung cancer patients receiving immune checkpoint inhibitors: a meta-analysis

Background and Purpose

Until now, it has been difficult to accurately predict the efficacy of immunotherapy in patients with non-small cell lung cancer (NSCLC). A novel indicator, the lung immune prognostic index (LIPI), has shown relatively high prognostic value in patients with solid cancer. Therefore, this study aimed to further identify the association between LIPI and the survival of patients with NSCLC who receive immune checkpoint inhibitors (ICIs).

Methods

Several electronic databases were searched for available publications up to April 23, 2023. Immunotherapy outcomes included overall survival (OS), progression-free survival (PFS), and hazard ratios (HRs) with 95% confidence intervals (CIs). Subgroup analysis based on the study design and comparison of the LIPI was conducted.

Results

In this meta-analysis, 21 studies with 9,010 patients were included in this meta-analysis. The pooled results demonstrated that elevated LIPI was significantly associated with poor OS (HR = 2.50, 95% CI:2.09-2.99, p < 0.001) and PFS (HR = 1.77, 95% CI:1.64-1.91, p < 0.001). Subgroup analyses stratified by study design (retrospective vs. prospective) and comparison of LIPI (1 vs. 0, 2 vs. 0, 1-2 vs. 0, 2 vs. 1 vs. 0, 2 vs. 0-1 and 2 vs. 1) showed similar results.

Conclusion

LIPI could serve as a novel and reliable prognostic factor in NSCLC treated with ICIs, and elevated LIPI predicts worse prognosis.

Tumor-associated neutrophils in pancreatic cancer progression and metastasis

Pancreatic cancer (PC) remains a challenge to modern-day cancer therapeutics, with a dismal five-year survival rate of 12%. Due to the pancreas's location and desmoplasia surrounding it, patients receive late diagnoses and fail to respond to chemotherapy regimens. Tumor-promoting inflammation, one of the emerging hallmarks of cancer, contributes to tumor cells' survival and proliferation. This inflammation often results from infiltrating leukocytes and pro-inflammatory cytokines released into the tumor microenvironment (TME). Neutrophils, one of our body's most prominent immune cells, are essential in sustaining the inflammation observed in the TME. Recent reports demonstrate that neutrophils are complicit in cancer progression and metastasis. Additionally, abundant data suggest that tumor-associated neutrophils (TANs) could be considered as one of the emerging targets for multiple cancer types, including PC. This review will focus on the most recent updates regarding neutrophil recruitments and functions in the cancer microenvironment and the potential development of neutrophils-targeted putative therapeutic strategies in PC.

Dysregulation of immunity by cigarette smoking promotes inflammation and cancer: A review

Smoking is a serious global health issue. Cigarette smoking contains over 7000 different chemicals. The main harmful components include nicotine, acrolein, aromatic hydrocarbons and heavy metals, which play the key role for cigarette-induced inflammation and carcinogenesis. Growing evidences show that cigarette smoking and its components exert a remarkable impact on regulation of immunity and dysregulated immunity promotes inflammation and cancer. Therefore, this comprehensive and up-to-date review covers four interrelated topics, including cigarette smoking, inflammation, cancer and immune system. The known harmful chemicals from cigarette smoking were summarized. Importantly, we discussed in depth the impact of cigarette smoking on the formation of inflammatory or tumor microenvironment, primarily by affecting immune effector cells, such as macrophages, neutrophils, and T lymphocytes. Furthermore, the main molecular mechanisms by which cigarette smoking induces inflammation and cancer, including changes in epigenetics, DNA damage and others were further summarized. This article will contribute to a better understanding of the impact of cigarette smoking on inducing inflammation and cancer.

Exploiting innate immunity for cancer immunotherapy

Immunotherapies have revolutionized the treatment paradigms of various types of cancers. However, most of these immunomodulatory strategies focus on harnessing adaptive immunity, mainly by inhibiting immunosuppressive signaling with immune checkpoint blockade, or enhancing immunostimulatory signaling with bispecific T cell engager and chimeric antigen receptor (CAR)-T cell. Although these agents have already achieved great success, only a tiny percentage of patients could benefit from immunotherapies. Actually, immunotherapy efficacy is determined by multiple components in the tumor microenvironment beyond adaptive immunity. Cells from the innate arm of the immune system, such as macrophages, dendritic cells, myeloid-derived suppressor cells, neutrophils, natural killer cells, and unconventional T cells, also participate in cancer immune evasion and surveillance. Considering that the innate arm is the cornerstone of the antitumor immune response, utilizing innate immunity provides potential therapeutic options for cancer control. Up to now, strategies exploiting innate immunity, such as agonists of stimulator of interferon genes, CAR-macrophage or -natural killer cell therapies, metabolic regulators, and novel immune checkpoint blockade, have exhibited potent antitumor activities in preclinical and clinical studies. Here, we summarize the latest insights into the potential roles of innate cells in antitumor immunity and discuss the advances in innate arm-targeted therapeutic strategies.

Mechanistic insights into the interplays between neutrophils and other immune cells in cancer development and progression

Cancer is considered a major public health concern worldwide and is characterized by an uncontrolled division of abnormal cells. The human immune system recognizes cancerous cells and induces innate immunity to destroy those cells. However, sustained tumors may protect themselves by developing immune escape mechanisms through multiple soluble and cellular mediators. Neutrophils are the most plenteous leukocytes in the human blood and are crucial for immune defense in infection and inflammation. Besides, neutrophils emancipate the antimicrobial contents, secrete different cytokines or chemokines, and interact with other immune cells to combat and successfully kill cancerous cells. Conversely, many clinical and experimental studies signpost that being a polarized and heterogeneous population with plasticity, neutrophils, particularly their subpopulations, act as a modulator of cancer development by promoting tumor metastasis, angiogenesis, and immunosuppression. Studies also suggest that tumor infiltrating macrophages, neutrophils, and other innate immune cells support tumor growth and survival. Additionally, neutrophils promote tumor cell invasion, migration and intravasation, epithelial to mesenchymal transition, survival of cancer cells in the circulation, seeding, and extravasation of tumor cells, and advanced growth and development of cancer cells to form metastases. In this manuscript, we describe and review recent studies on the mechanisms for neutrophil recruitment, activation, and their interplay with different immune cells to promote their pro-tumorigenic functions. Understanding the detailed mechanisms of neutrophil-tumor cell interactions and the concomitant roles of other immune cells will substantially improve the clinical utility of neutrophils in cancer and eventually may aid in the identification of biomarkers for cancer prognosis and the development of novel therapeutic approaches for cancer treatment.

Neutrophils in cancer carcinogenesis and metastasis

In recent years, neutrophils have attracted increasing attention because of their cancer-promoting effects. An elevated neutrophil-to-lymphocyte ratio is considered a prognostic indicator for patients with cancer. Neutrophils are no longer regarded as innate immune cells with a single function, let alone bystanders in the pathological process of cancer. Their diversity and plasticity are being increasingly recognized. This review summarizes previous studies assessing the roles and mechanisms of neutrophils in cancer initiation, progression, metastasis and relapse. Although the findings are controversial, the fact that neutrophils play a dual role in promoting and suppressing cancer is undeniable. The plasticity of neutrophils allows them to adapt to different cancer microenvironments and exert different effects on cancer. Given the findings from our own research, we propose a reasonable hypothesis that neutrophils may be reprogrammed into a cancer-promoting state in the cancer microenvironment. This new perspective indicates that neutrophil reprogramming in the course of cancer treatment is a problem worthy of attention. Preventing or reversing the reprogramming of neutrophils may be a potential strategy for adjuvant cancer therapy.

Human Antibody Domains and Fragments Targeting Neutrophil Elastase as Candidate Therapeutics for Cancer and Inflammation-Related Diseases

Neutrophil elastase (NE) is a serine protease released during neutrophil maturation. High levels of NE are related to lung tissue damage and poor prognosis in cancer; thus, NE is a potential target for therapeutic immunotherapy for multiple lung diseases and cancers. Here, we isolate and characterize two high-affinity, specific, and noncompetitive anti-NE antibodies Fab 1C10 and V_H 1D1.43 from two large phage-displayed human Fab and V_H libraries. After fusion with human IgG1 Fc, both of them (V_H-Fc 1D1.43 and IgG1 1C10) inhibit NE enzymatic activity with V_H-Fc 1D1.43 showing comparable inhibitory effects to that of the small molecule NE inhibitor SPCK and IgG1 1C10 exhibiting even higher (2.6-fold) activity than SPCK. Their epitopes, as mapped by peptide arrays combined with structural modeling, indicate different mechanisms for blocking NE activity. Both V_H-Fc and IgG1 antibodies block NE uptake by cancer cells and fibroblast differentiation. V_H-Fc 1D1.43 and IgG1 1C10 are promising for the antibody-based immunotherapy of cancer and inflammatory diseases.

Coagulopathy in Acute Promyelocytic Leukemia: Can We Go Beyond Supportive Care?

Acute promyelocytic leukemia (APL) is characterized by frequent complications due to a distinct coagulopathy. While advances in treatments have improved long-term survival, hemorrhagic and thrombotic complications remain the most common causes of death and morbidity. Improved understanding of the mechanisms of the coagulopathy associated with APL may lead to therapeutic interventions to mitigate the risk of hemorrhage and thrombosis.

The Multifunctional Roles of Short Palate, Lung, and Nasal Epithelium Clone 1 in Regulating Airway Surface Liquid and Participating in Airway Host Defense

Short palate, lung, and nasal epithelium clone 1 (SPLUNC1) is a kind of secretory protein, and gets expressed abundantly in normal respiratory epithelium of humans. As a natural immune molecule, SPLUNC1 is proved to be involved in inflammatory response and airway host defense. This review focuses on summarizing and discussing the role of SPLUNC1 in regulating airway surface liquid (ASL) and participating in airway host defense. PubMed and MEDLINE were used for searching and identifying the data in this review. The domain of bactericidal/permeability-increasing protein in SPLUNC1 and the α-helix, α4, are essential for SPLUNC1 to exert biological activities. As a natural innate immune molecule, SPLUNC1 plays a significant role in inflammatory response and airway host defense. Its special expression patterns are not only observed in physiological conditions, but also in some respiratory diseases. The mechanisms of SPLUNC1 in airway host defense include modulating ASL volume, acting as a surfactant protein, inhibiting biofilm formation, as well as regulating ASL compositions, such as LL-37, mucins, Neutrophil elastase, and inflammatory cytokines. Besides, potential correlations are found among these different mechanisms, especially among different ASL compositions, which should be further explored in more systematical frameworks. In this review, we summarize the structural characteristics and expression patterns of SPLUNC1 briefly, and mainly discuss the mechanisms of SPLUNC1 exerted in host defense, aiming to provide a theoretical basis and a novel target for future studies and clinical treatments.

Neutrophils in the Tumor Microenvironment

Neutrophils are the first responders to inflammation, infection, and injury. As one of the most abundant leukocytes in the immune system, neutrophils play an essential role in cancer progression, through multiple mechanisms, including promoting angiogenesis, immunosuppression, and cancer metastasis. Recent studies demonstrating elevated neutrophil to lymphocyte ratios suggest neutrophil as a potential therapeutic target and biomarker for disease status in cancer. This chapter will discuss the phenotypic and functional changes in the neutrophil in the tumor microenvironment, the underlying mechanism(s) of neutrophil facilitated cancer metastasis, and clinical potential of neutrophils as a prognostic/diagnostic marker and therapeutic target.

microRNA-146a Promotes Growth of Acute Leukemia Cells by Downregulating Ciliary Neurotrophic Factor Receptor and Activating JAK2/STAT3 Signaling

PURPOSE

Acute leukemia (AL) is classified as acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). This study aimed to investigate the effect of miR-146a on childhood AL and its underlying molecular mechanisms.

MATERIALS AND METHODS

Bone marrow samples were obtained from 39 AL children and 10 non-cancer controls. The expressions of miR-146a and ciliary neurotrophic factor receptor (CNTFR) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in ALL and AML pediatric patients, as well as ALL (Jurkat) and AML (HL-60) cells. Correlations between miR-146a and clinical indicators were explored. A targeting relationship between miR-146a and CNTFR was detected by dual luciferase reporter gene assay. Cell proliferation, apoptosis, migration, and invasion of Jurkat and HL-60 cells were measured by MTT assay, flow cytometry, and transwell assay, respectively. LIF expression was detected by qRT-PCR in Jurkat and HL-60 cells. The expression of p-JAK2, JAK2, p-STAT3, and STAT3 in HL-60 cells was measured by Western blot.

RESULTS

miR-146a was increased in ALL and AML pediatric patients, while CNTFR was decreased. miR-146a expression was associated with immunophenotype, karyotype, fusion gene, and SIL-TAL1. CNTFR was a target gene of miR-146a. miR-146a could promote cell proliferation, migration, and invasion, as well as inhibit cell apoptosis in Jurkat and HL-60 cells by downregulating CNTFR. Meanwhile, miR-146a inhibited the expression of LIF and activated JAK2/STAT3 pathway by downregulating CNTFR.

CONCLUSION

miR-146a could promote the proliferation, migration, and invasion and inhibit the apoptosis of AL Jurkat and HL-60 cells by downregulating CNTFR and activating the JAK2/STAT3 pathway.

Evaluation of the anti-inflammatory properties of the active constituents in Ginkgo biloba for the treatment of pulmonary diseases

Ginkgo biloba has long been used in ancient China for the treatment of cough, asthma, and other lung diseases. However, the active constituents in G. biloba for pulmonary disease treatment remain unclear. The objective of this study was to evaluate the anti-inflammatory active constituents in G. biloba and clarify their associated molecular mechanisms. The biological effects of different G. biloba extracts were evaluated in an ovalbumin-induced allergic mouse model. Anti-inflammatory compounds were present in the ethyl acetate phase of the extract, which were analysed by HPLC-MS. Biflavones were identified as the main compounds, which were further evaluated by docking calculations. Leukocyte elastase showed a high fit score with ginkgetin, one of the identified biflavones. The lowest binding free energy was -6.69 kcal mol-1. The effects of biflavones were investigated in vivo and in vitro. Ginkgetin markedly suppressed the abnormal expression of the Akt and p38 pathways in human neutrophil elastase (HNE)-stimulated A549 cells. Biflavones also decreased MUC5AC mRNA expression in HNE-stimulated A549 cells and the allergic mouse model. Inflammatory cells (neutrophils) and cytokines (IL-8) also decreased in mice treated with biflavones. The results suggest that G. biloba biflavones could inhibit the activity of leukocyte elastase. This in turn implicates G. biloba as a functional food for the treatment of airway inflammation.

Luteolin Partially Inhibits LFA-1 Expression in Neutrophils Through the ERK Pathway

Luteolin inhibits the adhesion of neutrophils to microvascular endothelial cells and plays an important anti-inflammatory role, owing to its mechanism of suppressing the expression of lymphocyte function-associated antigen-1 (LFA-1) in the neutrophils. Our study deals with the different signaling pathways participating in LFA-1 expression in neutrophils along with the regulation of luteolin in order to elucidate new anti-inflammatory targets of luteolin, thus providing a basis for clinical applications. In our study, neutrophils were separated using density gradient centrifugation and the cAMP levels were determined using ELISA. Additionally, phosphorylation levels of p38 mitogen-activated protein kinase (MAPK), extracellular regulated protein kinase (ERK), phosphatidylinositol-3-kinase (PI3K), and Janus kinase (JAK) were also detected by Western blotting. LFA-1 expression was estimated using flow cytometry. The results showed that inhibiting agents used against p38 MAPK, ERK, PI3K, and JAK could significantly inhibit LFA-1 expression on neutrophils (p < 0.05, p < 0.01). Luteolin also induced a noteworthy elevation of cAMP in neutrophil supernatants (p < 0.01). It could also significantly inhibit ERK phosphorylation (p < 0.05, p < 0.01), and had no obvious effect on p38 MAPK phosphorylation in neutrophils (p > 0.05). However, phosphorylation of PI3K and JAK was not detected in neutrophils. To conclude, the p38 MAPK, ERK, PI3K, and JAK pathways are involved in the regulation of LFA-1 expression in neutrophils, and luteolin partially inhibits LFA-1 expression by increasing cAMP levels and suppressing ERK phosphorylation.

Tumor-Associated Neutrophils in Cancer: Going Pro

The progression of cancer is not only about the tumor cell itself, but also about other involved players including cancer cell recruited immune cells, their released pro-inflammatory factors, and the extracellular matrix. These players constitute the tumor microenvironment and play vital roles in the cancer progression. Neutrophils—the most abundant white blood cells in the circulation system—constitute a significant part of the tumor microenvironment. Neutrophils play major roles linking inflammation and cancer and are actively involved in progression and metastasis. Additionally, recent data suggest that neutrophils could be considered one of the emerging targets for multiple cancer types. This review summarizes the most recent updates regarding neutrophil recruitments and functions in the tumor microenvironment as well as potential development of neutrophils-targeted putative therapeutic strategies.

Silencing the PIK3CA Gene Enhances the Sensitivity of Childhood Leukemia Cells to Chemotherapy Drugs by Suppressing the Phosphorylation of Akt

PURPOSE

This study aimed to investigate the effects of PIK3CA on the sensitivity of acute B lymphocytic leukemia cells (Nalm-6 cells) to chemotherapy drugs.

MATERIALS AND METHODS

Children's normal B lymphocytes and Nalm-6 cells were cultured. Nalm-6 cells were transfected with PIK3CA siRNA (siPIK3CA group) or its negative control (PIK3CA-Control group). Normal Nalm-6 cells were named Mock group. Nalm-6 cells transfected by PIK3CA siRNA were treated with Akt inhibitor (siPIK3CA+Akti-1/2 group). mRNA and protein expression was detected by qRT-PCR and Western blot. Proliferation and sensitivity to chemotherapeutic drugs was detected by MTT assay. Cell cycle and apoptosis was explored by low cytometry. Transwell assay was performed to test invasion.

RESULTS

PIK3CA mRNA (p=0.008) and protein (p=0.006) expression was higher in Nalm-6 cells than that in normal B lymphocytes. Compared with the Mock group and PIK3CA-Control group, Nalm-6 cells of the siPIK3CA group had lower OD495 values (all p<0.05) and invasion cell numbers (p=0.03 and p=0.025), as well as a higher proportion of G0/G1 phase cells (p=0.020 and p=0.022), percentage of apoptosis (p=0.016 and p=0.022), and inhibition rate (all p<0.05). pAkt expression in the siPIK3CA group (p=0.026 and p=0.031) and siPIK3CA+Akti-1/2 group (p=0.019 and p=0.023) was lower than that in the Mock group.

CONCLUSION

PIK3CA silencing inhibited Nalm-6 cell proliferation and invasion, and promoted their apoptosis and sensitivity to chemotherapeutic drugs, potentially through regulation of the PI3K/AKT signaling pathway.

Cxcr1 mediates recruitment of neutrophils and supports proliferation of tumor-initiating astrocytes in vivo

Neutrophils are first-responders to sites of infection and tissue damage including the inflamed tumor microenvironment. Increasing evidence suggests that crosstalk between tumors and neutrophils can affect the progression of established tumors. However, there is a gap in our understanding of the early events that lead to neutrophil recruitment to oncogene-transformed cells and how these pathways alter tumor progression. Here, we use optically transparent zebrafish larvae to probe the early signals that mediate neutrophil recruitment to Kras-transformed astrocytes. We show that zebrafish larvae with impaired neutrophil function exhibit reduced proliferation of transformed astrocytes supporting a critical role for tumor-associated neutrophils in the early progression of tumorigenesis. Moreover, using mutants and pharmacological inhibition, we show that the chemokine receptor Cxcr1 promotes neutrophil recruitment, proliferation of tumor-initiating cells, and neoplastic mass formation. These findings highlight the power of the larval zebrafish system to image and probe early events in the tumor-initiating microenvironment and demonstrate the potential for neutrophil recruitment signaling pathways such as Cxcl8-Cxcr1 as targets for anti-cancer therapies.

Location of NLS-RARα protein in NB4 cell and nude mice

In the majority of acute promyelocytic leukemia (APL) cases, translocons produce a promyelocytic leukemia protein-retinoic acid receptor α (PML-RARα) fusion gene. Studies have reported that neutrophil elastase (NE) cleaves bcr-1-derived PML-RAα in early myeloid cells, leaving only the nuclear localization signal (NLS) of PML attached to RARα. NLS-RARα promotes cell growth and inhibits differentiation in response to ATRA. However, the mechanisms by which NLS-RARα affects cell biological characteristics are yet to be fully elucidated. The present study found that the location of RARαwas altered after it was cleaved by NE. Firstly, NE was overexpressed during the preparation of recombinant plasmid NB-4/pCMV6-NE-Myc to cleave PML-RARα. The total protein expression levels of myc and NE and expression levels of NLS-RARα in nucleoprotein were detected by western blotting. Location of NLS-RARα protein was detected by immunofluorescence and confocal laser scanning. Secondly, a nude mice model was constructed and NE protein, NLS-RARα and RARα protein assays, and the location of NLS-RARα and RARα proteins were assessed as described. The present results showed that, compared with the control groups, the location of NLS-RARα protein was predominantly detected in the nucleus, whereas RARα was mainly distributed in the cytoplasm. These findings were consistent with those of the nude mice model, and these may be used as a foundation to explain the occurrence mechanism of APL.