CXCR4 chemokine receptor signaling induces apoptosis in acute myeloid leukemia cells via regulation of the Bcl-2 family members Bcl-XL, Noxa, and Bak

Targeting protein-protein interactions in drug discovery: Modulators approved or in clinical trials for cancer treatment

Protein-protein interactions (PPIs) form complex cellular networks fundamental to many key biological processes, including signal transduction, cell proliferation and DNA repair. In consequence, their perturbation is often associated with many human diseases. Targeting PPIs offers a promising approach in drug discovery and ongoing advancements in this field hold the potential to provide highly specific therapies for a wide range of complex diseases. Despite the development of PPI modulators is challenging, advances in the genetic, proteomic and computational level have facilitated their discovery and optimization. Focusing on anticancer drugs, in the last years several PPI modulators have entered clinical trials and venetoclax, which targets Bcl-2 family proteins, has been approved for treating different types of leukemia. This review discusses the clinical development status of drugs modulating several PPIs, such as MDM2-4/p53, Hsp90/Hsp90, Hsp90/CDC37, c-Myc/Max, KRAS/SOS1, CCR5/CCL5, CCR2/CCL2 or Smac/XIAP, in cancer drug discovery.

CXCR4 as a therapeutic target in acute myeloid leukemia

Extensive research on the CXCL12-CXCR4 axis in acute myeloid leukemia (AML) has resulted in the incorporation of novel anti-leukemia drugs targeting this axis into therapeutic strategies. However, despite this progress, a comprehensive and up-to-date review addressing the role of the CXCL12-CXCR4 axis in AML's oncogenic processes is lacking. In this review, we examine its molecular aspects influencing cancer progression, such as its impact on autonomous proliferation, apoptotic regulation, chemoresistance mechanisms, and interactions with non-leukemic cells such as MSCs and Treg cells. Additionally, we explore clinical implications, including prognosis, correlation with WBC count, blast count in the bone marrow and peripheral blood, as well as its association with FLT3-ITD, NPM1 mutations, and FAB classification. Finally, this paper extensively discusses drugs that specifically target the CXCL12-CXCR4 axis, including plerixafor/AMD3100, ulocuplumab, peptide E5, and motixafortide, shedding light on their potential therapeutic value in the treatment of AML.

Novel Anti-Enterovirus A71 Compounds Discovered by Repositioning Antivirals from the Open-Source MMV Pandemic Response Box

The open-source drug library, namely, MMV Pandemic Response Box, contains 153 antiviral agents, a chemically and pharmacologically diverse mixture of early-stage, emerging anti-infective scaffolds, and mature compounds currently undergoing clinical development. Hence, the Pandemic Response Box might contain compounds that bind and interfere with target molecules or cellular pathways that are conserved or shared among the closely related viruses with enterovirus A71 (EV-A71). This study aimed to screen antiviral agents included in the Pandemic Response Box for repurposing to anti-EV-A71 activity and investigate the inhibitory effects of the compounds on viral replication. The compounds' cytotoxicity and ability to rescue infected cells were determined by % cell survival using an SRB assay. The hit compounds were verified for anti-EV-A71 activity by virus reduction assays for viral RNA copy numbers, viral protein synthesis, and mature particle production using qRT-PCR, Western blot analysis, and CCID50 assay, respectively. It was found that some of the hit compounds could reduce EV-A71 genome replication and protein synthesis. D-D7 (2-pyridone-containing human rhinovirus 3C protease inhibitor) exhibited the highest anti-EV-A71 activity. Even though D-D7 has been originally indicated as a polyprotein processing inhibitor of human rhinovirus 3C protease, it could be repurposed as an anti-EV-A71 agent.

Chemokines as Prognostic Factor in Colorectal Cancer Patients: A Systematic Review and Meta-Analysis

Chemokines orchestrate many aspects of tumorigenic processes such as angiogenesis, apoptosis and metastatic spread, and related receptors are expressed on tumor cells as well as on inflammatory cells (e.g., tumor-infiltrating T cells, TILs) in the tumor microenvironment. Expressional changes of chemokines and their receptors in solid cancers are common and well known, especially in affecting colorectal cancer patient outcomes. Therefore, the aim of this current systematic review and meta-analysis was to classify chemokines as a prognostic biomarker in colorectal cancer patients. A systematic literature search was conducted in PubMed, CENTRAL and Web of Science. Information on the chemokine expression of 25 chemokines in colorectal cancer tissue and survival data of the patients were investigated. The hazard ratio of overall survival and disease-free survival with chemokine expression was examined. The risk of bias was analyzed using Quality in Prognosis Studies. Random effects meta-analysis was performed to determine the impact on overall respectively disease survival. For this purpose, the pooled hazard ratios (HR) and their 95% confidence intervals (CI) were used for calculation. Twenty-five chemokines were included, and the search revealed 5556 publications. A total of thirty-one publications were included in this systematic review and meta-analysis. Overexpression of chemokine receptor CXCR4 was associated with both a significantly reduced overall survival (HR = 2.70, 95%-CI: 1.57 to 4.66, p = 0.0003) as well as disease-free survival (HR = 2.68, 95%-CI: 1.41 to 5.08, p = 0.0026). All other chemokines showed either heterogeneous results or few studies were available. The overall risk of bias for CXCR4 was rated low. At the current level of evidence, this study demonstrates that CXCR4 overexpression in patients with colorectal cancer is associated with a significantly diminished overall as well as disease-free survival. Summed up, this systematic review and meta-analysis reveals CXCR4 as a promising prognostic biomarker. Nevertheless, more evidence is needed to evaluate CXCR4 and its antagonists serving as new therapeutic targets.

The CXCR4 might be a potential biomarker for esophageal squamous cell carcinoma: A meta-analysis

OBJECTIVE

To evaluate the relationship between CXCL12/CXCR4 and the progress, prognosis of esophageal squamous cell carcinoma (ESCC), providing evidence for potential early diagnosis, clinical treatment, prognosis evaluation, and therapeutic target of ESCC.

METHODS

Databases of PubMed, the Cochrane Library, Embase, and Web of Science were searched for the relationship between CXCL12/CXCR4 and clinicopathological characteristics and survival time of ESCC. Stata16.0 software was used to conduct meta-analysis.

RESULTS

A total of 10 studies involving 1216 cases of patients with ESCC were included in our study. The results indicated that high-level expression of CXCR4 was significantly correlated with tumor differentiation [OR = 0.69, 95% confidence interval (CI): (0.50, 0.97)], tumor infiltration [OR = 0.39, 95% CI: (0.25, 0.61)], lymph node metastasis [OR = 0.36, 95% CI: (0.21, 0.61)], clinical stage [OR = 0.33, 95% CI: (0.24, 0.45)] of ESCC. The expression of CXCR4 was also significantly correlated with OS [HR = 2.00, 95% CI: (1.63, 2.45)] and disease-free survival [HR = 1.76, 95% CI: (1.44, 2.15)] in patients of ESCC after surgical resection. No significant relationship was observed between the expression of CXCL12 and the clinicopathological characteristics of ESCC.

CONCLUSION

CXCR4 might be a potential biomarker for the progress and prognosis evaluation, and therapeutic target for ESCC.

A hypoxia-related genes prognostic risk model, and mechanisms of hypoxia contributing to poor prognosis through immune microenvironment and drug resistance in acute myeloid leukemia

Objective: Acute myeloid leukemia (AML) is a malignant hematologic cancer with poor prognosis. Emerging evidence suggests a close association between AML progression and hypoxia. The purpose of this study was to establish a new risk prognostic model for AML based on hypoxia-related genes, and to explore the mechanisms by which hypoxia-related genes affect the prognosis of AML based on tumor immune microenvironment (TIME) and drug resistance. Methods: The AML patient samples obtained from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database were classified into C1 and C2 based on hypoxia-related genes, followed by analysis utilizing Gene Ontology (GO), Kyoto Encyclopaedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA). Through univariate and LASSO Cox regression analysis, the hypoxia-related hub genes 26S proteasome non-ATPase regulatory subunit 11 (PSMD11) and 26S proteasome non-ATPase regulatory subunit 14 (PSMD14) were identified to construct the model. AML patient samples were obtained from the TARGET and The Cancer Genome Atlas (TCGA) databases, serving as the training and the validation sets, and were stratified into high-risk and low-risk group according to the median risk score. The correlations between the model and TIME and anti-tumor drugs were analysed using CIBERSORT and Genomics of Drug Sensitivity in Cancer (GDSC) databases. The expressions of PSMD11/PSMD14 in clinical samples and AML sensitive and drug-resistant cell lines were detected by Western blot and real-time PCR. Results: The C1 group with high expression of hypoxia-related genes had lower overall survival (OS). Immune-related signaling pathways were different between C1/C2, and hypoxia was positively correlated with the activation of mammalian target of rapamycin (mTOR) signaling pathway. The model had good accuracy in both the training and the validation sets. The high-risk group exhibited lower OS and TIME activity, and was more sensitive to several anti-tumor drugs. PSMD11/PSMD14 were highly expressed in relapsed patients and AML drug-resistant cell lines. Conclusion: The established novel risk prognostic model and experiment results offer valuable insights for predicting AML prognosis and guiding drug selection. It also provides a fundamental framework for the mechanisms through which hypoxia impacts AML prognosis by modulating TIME and drug resistance.

Construction of an acute myeloid leukemia prognostic model based on m6A-related efferocytosis-related genes

Background

One of the most prevalent hematological system cancers is acute myeloid leukemia (AML). Efferocytosis-related genes (ERGs) and N6-methyladenosine (m6A) have an important significance in the progression of cancer, and the metastasis of tumors.

Methods

The AML-related data were collected from The Cancer Genome Atlas (TCGA; TCGA-AML) database and Gene Expression Omnibus (GEO; GSE9476, GSE71014, and GSE13159) database. The "limma" R package and Venn diagram were adopted to identify differentially expressed ERGs (DE-ERGs). The m6A related-DE-ERGs were obtained by Spearman analysis. Subsequently, univariate Cox and Least Absolute Shrinkage and Selection Operator (LASSO) were used to construct an m6A related-ERGs risk signature for AML patients. The possibility of immunotherapy for AML was explored. The pRRophetic package was adopted to calculate the IC50 of drugs for the treatment of AML. Finally, the expression of characterized genes was validated by quantitative reverse transcription-PCR (qRT-PCR).

Results

Based on m6A related-DE-ERGs, a prognostic model with four characteristic genes (UCP2, DOCK1, SLC14A1, and SLC25A1) was constructed. The risk score of model was significantly associated with the immune microenvironment of AML, with four immune cell types, 14 immune checkpoints, 20 HLA family genes and, immunophenoscore (IPS) all showing differences between the high- and low-risk groups. A total of 56 drugs were predicted to differ between the two groups, of which Erlotinib, Dasatinib, BI.2536, and bortezomib have been reported to be associated with AML treatment. The qRT-PCR results showed that the expression trends of DOCK1, SLC14A1 and SLC25A1 were consistent with the bioinformatics analysis.

Conclusion

In summary, 4 m6A related- ERGs were identified and the corresponding prognostic model was constructed for AML patients. This prognostic model effectively stratified the risk of AML patients.

Lycium ruthenicum Murr. anthocyanins inhibit hyperproliferation of synovial fibroblasts from rheumatoid patients and the mechanism study powered by network pharmacology

BACKGROUND

Rheumatoid arthritis (RA), is a typical autoimmune disease affecting nearly 1% of the world's population. The dysfunctional hyperproliferation of synovial fibroblast (SF) in articular cartilage of RA patients is considered as the essential etiology. Traditional chemotherapeutic agents for RA treatment are imperfect for their high cost and unpredictable side-effects. L. ruthenicum anthocyanins (LRAC) is a natural product that of potential for therapeutic application against RA.

METHODS

LRAC was characterized by UPLC-MS/MS. Bioinformatics analyses based on network pharmacology were applied to predict the potential targets of LRAC, and to select DEGs (differentially expressed genes) caused by RA pathogenesis from GSE77298. Interactions between LRAC and the predicted targets were evaluated by molecular docking. Effects of LRAC on SFs from RA patients were examined by in vitro assays, which were analyzed by flow cytometry and western blotting (WB).

RESULTS

LRAC was able to inhibit the abnormal proliferation and aggressive invasion of SFs from RA patients. LRAC was mainly constituted by petunidin (82.7%), with small amount of delphinidin (12.9%) and malvidin (4.4%) in terms of anthocyanidin. Bioinformatics analyses showed that in 3738 RA-related DEGs, 58 of them were collectively targeted by delphinidin, malvidin and delphinidin. AR, CDK2, CHEK1, HIF1A, CXCR4, MMP2 and MMP9, the seven hub genes constructed a central network mediating the signal transduction. Molecular docking confirmed the high affinities between the LRAC ligands and the protein receptors encoded by the hub genes. The in vitro assays validated that LRAC repressed the growth of RASF by cell cycle arresting and cell invasion paralyzing (c-Myc/p21/CDK2), initiating cell apoptosis (HIF-1α/CXCR4/Bax/Bcl-2), and inducing pyroptosis via ROS-dependent pathway (NOX4/ROS/NLRP3/IL-1β/Caspase-1).

CONCLUSION

LRAC can selectively inhibit the proliferation of RASFs, without side-effecting immunosuppression that usually occurred for RA treatment using MTX (methotrexate). These findings demonstrate the potential application of LRAC as a phytomedicine for RA treatment, and provide a valid approach for exploring natural remedies against autoimmune diseases.

CRISPR screens identify novel regulators of cFLIP dependency and ligand-independent, TRAIL-R1-mediated cell death

Kaposi's sarcoma-associated herpesvirus (KSHV) causes primary effusion lymphoma (PEL). PEL cell lines require expression of the cellular FLICE inhibitory protein (cFLIP) for survival, although KSHV encodes a viral homolog of this protein (vFLIP). Cellular and viral FLIP proteins have several functions, including, most importantly, the inhibition of pro-apoptotic caspase 8 and modulation of NF-κB signaling. To investigate the essential role of cFLIP and its potential redundancy with vFLIP in PEL cells, we first performed rescue experiments with human or viral FLIP proteins known to affect FLIP target pathways differently. The long and short isoforms of cFLIP and molluscum contagiosum virus MC159L, which are all strong caspase 8 inhibitors, efficiently rescued the loss of endogenous cFLIP activity in PEL cells. KSHV vFLIP was unable to fully rescue the loss of endogenous cFLIP and is therefore functionally distinct. Next, we employed genome-wide CRISPR/Cas9 synthetic rescue screens to identify loss of function perturbations that can compensate for cFLIP knockout. Results from these screens and our validation experiments implicate the canonical cFLIP target caspase 8 and TRAIL receptor 1 (TRAIL-R1 or TNFRSF10A) in promoting constitutive death signaling in PEL cells. However, this process was independent of TRAIL receptor 2 or TRAIL, the latter of which is not detectable in PEL cell cultures. The requirement for cFLIP is also overcome by inactivation of the ER/Golgi resident chondroitin sulfate proteoglycan synthesis and UFMylation pathways, Jagunal homolog 1 (JAGN1) or CXCR4. UFMylation and JAGN1, but not chondroitin sulfate proteoglycan synthesis or CXCR4, contribute to TRAIL-R1 expression. In sum, our work shows that cFLIP is required in PEL cells to inhibit ligand-independent TRAIL-R1 cell death signaling downstream of a complex set of ER/Golgi-associated processes that have not previously been implicated in cFLIP or TRAIL-R1 function.

ScRNA-seq revealed targeting regulator of G protein signaling 1 to mediate regulatory T cells in Hepatocellular carcinoma

BACKGROUND

Regulatory T cells (Tregs) are central to determine immune response outcomes, thus targeting Tregs for immunotherapy is a promising strategy against tumor development and metastasis.

OBJECTIVES

The objective of this study was to identify genes for targeting Tregs to improve the outcome of HCC.

METHODS

We integrated expression data from different samples to remove batch effects and further applied embedding function in Scanpy to conduct sub-clustering of CD4+ T cells in HCC for each of two independent scRNA-seq data. The activity of transcription factors (TFs) was inferred by DoRothEA. Gene expression network analysis was performed in WGCNA R package. We finally used R packages (survminer and survival) to conduct survival analysis. Multiplex immunofluorescence analysis was performed to validate the result from bioinformatic analyses.

RESULTS

We found that regulator of G protein signaling 1 (RGS1) expression was significantly elevated in Tregs compared to other CD4+ T cells in two independent public scRNA-seq datasets, and increased RGS1 predicted inferior clinical outcome of HCC patients. Multiplex immunofluorescence analysis supported that the higher expression of RGS1 in HCC Tregs in tumor tissue compared to it in adjacent tissue. Moreover, RGS1 expression in Tregs was positively correlated with the expression of marker genes of Tregs, C-X-C chemokine receptor 4 (CXCR4), and three CXCR4-dependent genes in both scRNA-seq and bulk RNA-seq data. We further identified that these three genes were selectively expressed in Tregs as compared to other CD4+ T cells. The activities of two transcription factors, recombination signal binding protein for immunoglobulin kappa J region (RBPJ) and yin yang 1 (YY1), were significantly different in HCC Tregs with RGS1 high and RGS1 low.

CONCLUSIONS

Our findings suggested that RGS1 may regulate Treg function possibly through CXCR4 signaling and RGS1 could be a potential target to improve responses for immunotherapy in HCC.

Recent Emerging Immunological Treatments for Primary Brain Tumors: Focus on Chemokine-Targeting Immunotherapies

Primary brain tumors are a leading cause of death worldwide and are characterized by extraordinary heterogeneity and high invasiveness. Current drug and radiotherapy therapies combined with surgical approaches tend to increase the five-year survival of affected patients, however, the overall mortality rate remains high, thus constituting a clinical challenge for which the discovery of new therapeutic strategies is needed. In this field, novel immunotherapy approaches, aimed at overcoming the complex immunosuppressive microenvironment, could represent a new method of treatment for central nervous system (CNS) tumors. Chemokines especially are a well-defined group of proteins that were so named due to their chemotactic properties of binding their receptors. Chemokines regulate the recruitment and/or tissue retention of immune cells as well as the mobilization of tumor cells that have undergone epithelial–mesenchymal transition, promoting tumor growth. On this basis, this review focuses on the function and involvement of chemokines and their receptors in primary brain tumors, specifically examining chemokine-targeting immunotherapies as one of the most promising strategies in neuro-oncology.

The magnitude of CXCR4 signaling regulates resistance to quizartinib in FLT3/ITD+ cells via RUNX1

CXCR4 antagonists sensitize FLT3/ITD⁺ AML cells to FLT3 inhibitors; however, CXCR4 signaling can induce apoptosis in AML cells, raising the question of whether CXCR4 signaling exerts divergent effects on FLT3/ITD⁺ cells. The present study investigated the paradoxical function of CXCR4 in resistance to FLT3 inhibitors. The FLT3 inhibitor quizartinib significantly decreased the number of FLT3/ITD⁺ Ba/F3 cells, whereas 1 ng/ml CXCL12 showed a significant protective effect against quizartinib. In contrast, CXCL12 over 100 ng/ml significantly decreased FLT3/ITD⁺ cell viability with concomitant downregulation of Runx1. Moreover, the survival of FLT3/ITD⁺ Ba/F3 or MOLM13 cells with low surface CXCR4 expression incubated with quizartinib was significantly enhanced by 100 ng/ml CXCL12; however, this protective effect of CXCL12 against quizartinib was barely detected in cells with high surface CXCR4 expression. Although silencing Runx1 downregulated CXCR4 expression, RUNX1 expression levels were significantly higher in CXCR4^LOW FLT3/ITD⁺ Ba/F3 cells incubated with 100 ng/ml CXCL12 than in CXCR4^HIGH cells, coincident with an increase in FLT3 phosphorylation. Silencing RUNX1 partially abrogated resistance to quizartinib in CXCR4^LOW cells incubated with CXCL12, whereas ectopic RUNX1 significantly restored resistance in CXCR4^HIGH cells. These results indicate that CXCR4 signaling of different magnitudes paradoxically regulates resistance to quizartinib in FLT3/ITD⁺ cells via RUNX1.

Interactions of the chemokines CXCL11 and CXCL12 in human tumor cells

BACKGROUND

The chemokines, CXCL12 and CXCL11, are upregulated in tumors from many organs and control their progression. CXCL12 and CXCL11 affect tumor cell functions by either binding their prime receptors, CXCR4 and CXCR3, respectively, and/or CXCR7 as a common second chemokine receptor. In humans, CXCR3 exists in the functional splice variants, CXCR3A and CXCR3B, which either have pro- or anti-tumor activity, respectively. Despite the intimate crosstalk between the CXCL12- and CXCL11-system, the impact of a combination of CXCL12 and CXCL11 on tumor progression remains vague.

METHODS

In the present work, we have analyzed CXCL12 and CXCL11 for combined effects on migration, invasion, proliferation, and cytostatic-induced apoptosis of the human tumor cells, A549, A767, A772, DLD-1, and MDA-MB-231.

RESULTS

We demonstrate that the mode of interaction differs with respect to cell type and function and allows for either potentiation, attenuation or no changes of cellular responses. The divergent responses are not the result of the distinct use of different CXCL12- and CXCL11-receptors by the respective tumor cells, but in case of cell migration seem to be associated with the activation of p38 signaling pathways.

CONCLUSIONS

Our findings point to therapeutic limitations of ongoing efforts to selectively target CXCR3, CXCR4, or CXCR7 in cancer patients, and rather favor individualized targeting strategies.

ABAT gene expression associated with the sensitivity of hypomethylating agents in myelodysplastic syndrome through CXCR4/mTOR signaling

The factors that affect hypomethylating agents (HMAs) sensitivity in myelodysplastic syndrome (MDS) are complex and multifaceted. They include DNA methylation, gene expression, mutation, etc. However, the underlying mechanisms are still not clearly illustrated. In the present work, ABAT gene expression was associated with HMAs sensitivity. It was found that ABAT gene interference increased the sensitivity of HL-60 and THP-1 cells to HMAs treatment, while ABAT overexpression decreased its sensitivity. RNA-sequencing analysis showed that ABAT knockdown activated both interferon I and interferon-gamma signaling while inhibiting the secondary metabolic synthesis and arginine metabolic process. Gas chromatography-mass spectrometry (GC-MS) based metabolic profiling also demonstrated that ABAT gene knockdown affected arginine, alanine, aspartate, and glutamate metabolism, in addition to the biosynthesis of valine, leucine, and isoleucine, and the metabolism of beta-alanine. The ABAT gene expression downregulation could activate the CXCR4/mTOR signaling pathway, which was related to HMAs sensitivity. CXCR4 expression was regulated by mTOR activity and vice versa. In vivo, mice injected with ABAT gene knockdown cells lived longer than control mice after HMAs treatment. Overall, this study elucidates the novel regulatory mechanisms of HMAs sensitivity and provides a potential therapeutic target in MDS.

Cellular landscaping of cisplatin resistance in cervical cancer

Cervical cancer (CC) caused by human papillomavirus (HPV) is one of the largest causes of malignancies in women worldwide. Cisplatin is one of the widely used drugs for the treatment of CC is rendered ineffective owing to drug resistance. This review highlights the cause of resistance and the mechanism of cisplatin resistance cells in CC to develop therapeutic ventures and strategies that could be utilized to overcome the aforementioned issue. These strategies would include the application of nanocarries, miRNA, CRIPSR/Cas system, and chemotherapeutics in synergy with cisplatin to not only overcome the issues of drug resistance but also enhance its anti-cancer efficiency. Moreover, we have also discussed the signaling network of cisplatin resistance cells in CC that would provide insights to develop therapeutic target sites and inhibitors. Furthermore, we have discussed the role of CC metabolism on cisplatin resistance cells and the physical and biological factors affecting the tumor microenvironments.

Functional Tumor Targeting Nano-Systems for Reprogramming Circulating Tumor Cells with In Situ Evaluation on Therapeutic Efficiency at the Single-Cell Level

Tumor heterogeneity is primarily responsible for treatment resistance and cancer relapses. Being critically important to address this issue, the timely evaluation of the appropriateness of therapeutic actions at the single-cell level is still facing challenges. By using multi-functionalized nano-systems with the delivery vector composed of histone for plasmids loading, hyaluronic acid for tumor targeting, and a fusion peptide for C-X-C motif chemokine receptor 4 (CXCR4） targeting as well as nuclear localization, the reprogramming of circulating tumor cells (CTCs) with in situ detection on biomarkers at the single-cell level is realized. By efficient co-delivery of the genome editing plasmid for CXCR4 knockout and molecular beacons for detection of upregulated mRNA biomarkers into CTCs in unprocessed whole blood, the therapeutic outcomes of genome editing at the single-cell level can be in situ evaluated. The single-cell analysis shows that CXCR4 in CTCs of cancer patients is efficiently downregulated, resulting in upregulated anticancer biomarkers such as p53 and p21. The study provides a facile strategy for in-depth profiling of cancer cell responses to therapeutic actions at single-cell resolution to evaluate the outcomes of treatments timely and conveniently.

CXCR4 Mediates Enhanced Cell Migration in CALM-AF10 Leukemia

Leukemia transformed by the CALM-AF10 chromosomal translocation is characterized by a high incidence of extramedullary disease, central nervous system (CNS) relapse, and a poor prognosis. Invasion of the extramedullary compartment and CNS requires leukemia cell migration out of the marrow and adherence to the cells of the local tissue. Cell adhesion and migration are increasingly recognized as contributors to leukemia development and therapeutic response. These processes are mediated by a variety of cytokines, chemokines, and their receptors, forming networks of both secreted and cell surface factors. The cytokines and cytokine receptors that play key roles in CALM-AF10 driven leukemia are unknown. We find high cell surface expression of the cytokine receptor CXCR4 on leukemia cells expressing the CALM-AF10 oncogenic protein, contributing to the migratory nature of this leukemia. Our discovery of altered cytokine receptor expression and function provides valuable insight into the propagation and persistence of CALM-AF10 driven leukemia.

Effect of erythropoietin administration on expression of mRNA brain-derived Neutrophic factor, levels of stromal cell-derived Factor-1, and neuron specific enolase in brain injury model Sprague Dawley

BACKGROUND

Traumatic brain injury (TBI) is a complicated condition that is the primary cause of death and disability in children and young adults in developed countries. Various kinds of therapy have been carried out in the management of brain injury, one of which is the administration of erythropoietin (EPO). There are not many studies in Indonesia have proven that EPO administration is effective on parameters such as stromal cell-derived factor 1 (SDF-1), brain-derived neurotrophic factor (BDNF mRNA), and neuron-specific enolase (NSE) in brain injury patients. The purpose of this study was to see how EPO affected BDNF mRNA expression, SDF-1 serum levels, and NSE levels in experimental rats with TBI.

METHODS

This study was conducted using a rat head injury model. Fifteen rats were randomly assigned to one of three groups: A, B, or C. EPO was administered subcutis with a dose of 30.000 U/kg. Blood samples were taken after brain injury (H0), 12 h (H12), and 24 h (H24) after brain injury. Serum level of SDF-1 and NSE were measured using mRNA BDNF gene expression was measured with Real-Time-PCR, and ELISA.

RESULTS

This study found EPO increase BDNF mRNA expression in group C at H-12 (7,92 ± 0.51 vs 6.45 ± 0.33) compared to group B, and at H-24 (9.20 ± 0.56 vs 7.22 ± 0.19); increase SDF-1 levels in group C at H-12 (7,56 ± 0,54) vs 4,62 ± 0,58) compared to group B, and at H-24 (11,32 ± 4,55 vs 2,55 ± 0,70); decrease serum NSE levels in group C at H-12 (17,25 ± 2,02 vs 29,65 ± 2,33) compare to group B and at H-24 (12,14 ± 2,61 vs 37,31 ± 2,76); the values are significantly different with p < 0,05.

CONCLUSION

EPO may have neuroprotective and anti-inflammatory properties in TBI by increasing mRNA BDNF expression and serum SDF-1 levels, and decrease serum NSE levels.

A hypoxia risk signature for the tumor immune microenvironment evaluation and prognosis prediction in acute myeloid leukemia

Acute myeloid leukemia (AML) is the most prevalent form of acute leukemia. Patients with AML often have poor clinical prognoses. Hypoxia can activate a series of immunosuppressive processes in tumors, resulting in diseases and poor clinical prognoses. However, how to evaluate the severity of hypoxia in tumor immune microenvironment remains unknown. In this study, we downloaded the profiles of RNA sequence and clinicopathological data of pediatric AML patients from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database, as well as those of AML patients from Gene Expression Omnibus (GEO). In order to explore the immune microenvironment in AML, we established a risk signature to predict clinical prognosis. Our data showed that patients with high hypoxia risk score had shorter overall survival, indicating that higher hypoxia risk scores was significantly linked to immunosuppressive microenvironment in AML. Further analysis showed that the hypoxia could be used to serve as an independent prognostic indicator for AML patients. Moreover, we found gene sets enriched in high-risk AML group participated in the carcinogenesis. In summary, the established hypoxia-related risk model could act as an independent predictor for the clinical prognosis of AML, and also reflect the response intensity of the immune microenvironment in AML.

CXCL12-CXCR4/CXCR7 Axis in Colorectal Cancer: Therapeutic Target in Preclinical and Clinical Studies

Chemokines are chemotactic cytokines that promote cancer growth, metastasis, and regulate resistance to chemotherapy. Stromal cell-derived factor 1 (SDF1) also known as C-X-C motif chemokine 12 (CXCL12), a prognostic factor, is an extracellular homeostatic chemokine that is the natural ligand for chemokine receptors C-X-C chemokine receptor type 4 (CXCR4), also known as fusin or cluster of differentiation 184 (CD184) and chemokine receptor type 7 (CXCR7). CXCR4 is the most widely expressed rhodopsin-like G protein coupled chemokine receptor (GPCR). The CXCL12-CXCR4 axis is involved in tumor growth, invasion, angiogenesis, and metastasis in colorectal cancer (CRC). CXCR7, recently termed as atypical chemokine receptor 3 (ACKR3), is amongst the G protein coupled cell surface receptor family that is also commonly expressed in a large variety of cancer cells. CXCR7, like CXCR4, regulates immunity, angiogenesis, stem cell trafficking, cell growth and organ-specific metastases. CXCR4 and CXCR7 are expressed individually or together, depending on the tumor type. When expressed together, CXCR4 and CXCR7 can form homo- or hetero-dimers. Homo- and hetero-dimerization of CXCL12 and its receptors CXCR4 and CXCR7 alter their signaling activity. Only few drugs have been approved for clinical use targeting CXCL12-CXCR4/CXCR7 axis. Several CXCR4 inhibitors are in clinical trials for solid tumor treatment with limited success whereas CXCR7-specific inhibitors are still in preclinical studies for CRC. This review focuses on current knowledge of chemokine CXCL12 and its receptors CXCR4 and CXCR7, with emphasis on targeting the CXCL12-CXCR4/CXCR7 axis as a treatment strategy for CRC.

Normal and leukemic stem cell niche interactions

PURPOSE OF REVIEW

Normal hematopoietic stem cells (HSCs) and leukemic stem cells (LSCs) interact with the stem cell niche bone marrow in different ways. Understanding the potentially unique microenvironmental regulation of LSCs is key to understanding in-vivo leukemogenic mechanisms and developing novel antileukemic therapies.

RECENT FINDINGS

When leukemic cells are engrafted in the stem cell niche, the cellular nature of the niche - including mesenchymal stromal cells - is reprogramed. Altered mesenchymal cells selectively support leukemic cells and reinforce the pro-leukemic environment. As the niche plays an active role in leukemogenesis, its remodeling may significantly influence the leukemogenic pattern, and cause differences in clinical prognosis. Notably, niche cells could be stimulated to revert to a pronormal/antileukemic state, creating potential for niche-based antileukemic therapy.

SUMMARY

Bone marrow microenvironments are under dynamic regulation for normal and leukemic cells, and there is bi-directional control of leukemic cells in the niche. Leukemic cells are both protected by stroma and able to reprogram stromal cells to transform the niche to a state, which reinforces leukemogenesis. Because of its dynamic nature, the niche could be converted to an environment with antileukemic properties, making it an attractive target for therapy.

Targeting Leukemia Stem Cell-Niche Dynamics: A New Challenge in AML Treatment

One of the most urgent needs in AML is to improve the disease cure rate as relapse still occurs in 60–80% of patients. Recent evidence suggests that dismal clinical outcomes may be improved by a better definition of the tight interaction between the AML cell population and the bone marrow (BM) microenvironment (“the niche”); the latter has been progressively highlighted to have an active role in the disease process. It has now been well established that the leukemic population may misinterpret niche-derived signals and remodel the niche, providing a shelter to AML cells and protecting them from the cytotoxic effects of chemoradiotherapy. Novel imaging technological advances and preclinical disease models have revealed that, due to the finite number of BM niches, leukemic stem cells (LSCs) and normal hematopoietic stem cells (HSCs) compete for the same functional areas. Thus, the removal of LSCs from the BM niche and the promotion of normal HSC engraftment should be the primary goals in antileukemic research. In addition, it is now becoming increasingly clear that AML-niche dynamics are disease stage specific. In AML, the niche has been linked to disease pathogenesis in the preleukemic stage, the niche becomes permissive once leukemic cells are established, and the niche is transformed into a self-reinforcing structure at a later disease stage. These concepts have been fostered by the demonstration that, in unrelated AML types, endosteal vessel loss occurs as a primary AML-induced niche alteration, and additional AML-induced alterations of the niche and normal hematopoiesis evolve focally and in parallel. Obviously, this endosteal vessel loss plays a fundamental role in AML pathogenesis by causing excessive vascular permeability, hypoxia, altered perfusion, and reduced drug delivery. Each of these alterations may be effectively targeted by various therapeutic procedures, but preservation of endosteal vessel integrity might be the best option for any future antileukemic treatment.

Artificial Intelligence Approach to Find Lead Compounds for Treating Tumors

It has been demonstrated that MMP13 enzyme is related to most cancer cell tumors. The world's largest traditional Chinese medicine database was applied to screen for structure-based drug design and ligand-based drug design. To predict drug activity, machine learning models (Random Forest (RF), AdaBoost Regressor (ABR), Gradient Boosting Regressor (GBR)), and Deep Learning models were utilized to validate the Docking results, and we obtained an R² of 0.922 on the training set and 0.804 on the test set in the RF algorithm. For the Deep Learning algorithm, R² of the training set is 0.90, and R² of the test set is 0.810. However, these TCM compounds fly away during the molecular dynamics (MD) simulation. We seek another method: peptide design. All peptide database were screened by the Docking process. Modification peptides were optimized the interaction modes, and the affinities were assessed with ZDOCK protocol and Refine Docked protein protocol. The 300 ns MD simulation evaluated the stability of receptor-peptide complexes. The double-site effect appeared on S2, a designed peptide based on a known inhibitor, when complexed with BCL2. S3, a designed peptide referred from endogenous inhibitor P16, competed against cyclin when binding with CDK6. The MDM2 inhibitors S5 and S6 were derived from the P53 structure and stable binding with MDM2. A flexible region of peptides S5 and S6 may enhance the binding ability by changing its own conformation, which was unforeseen. These peptides (S2, S3, S5, and S6) are potentially interesting to treat cancer; however, these findings need to be affirmed by biological testing, which will be conducted in the near future.

CD97 expression is associated with poor overall survival in acute myeloid leukemia

CD97, a member of the adhesion G-protein coupled receptor family, is normally expressed on leukocytes and smooth muscles. CD97 is also expressed in a variety of solid cancers, particularly those with aggressive metastatic phenotypes. Here we characterize the clinical significance of CD97 in acute myeloid leukemia (AML). We analyzed 173 patients from the TCGA AML data set and found that CD97 was higher in cytogenetically normal patients compared with cytogenetically abnormal patients (p = 0.023). High CD97 was also associated with NPM1 mutations (p = 0.0033). Patients with high CD97 expression had shorter overall (median: 7.35 months vs. 24.1 months, p = 0.0015) and disease-free (median DFS: 8.2 months vs. 18.2 months, p = 0.017) survival. Importantly, we identified pathways involved in the leukemia stem cell interaction with the bone marrow niche, such as integrin, CXCR4, and interleukin-8, among the most upregulated signaling pathways in patients with high CD97 expression. Our results suggest that high CD97 expression is associated with poor clinical outcome and indicate a need for future functional and mechanistic studies to investigate the role of CD97 in AML.

Chemokines in COPD: From Implication to Therapeutic Use

: Chronic Obstructive Pulmonary Disease (COPD) represents the 3rd leading cause of death in the world. The underlying pathophysiological mechanisms have been the focus of extensive research in the past. The lung has a complex architecture, where structural cells interact continuously with immune cells that infiltrate into the pulmonary tissue. Both types of cells express chemokines and chemokine receptors, making them sensitive to modifications of concentration gradients. Cigarette smoke exposure and recurrent exacerbations, directly and indirectly, impact the expression of chemokines and chemokine receptors. Here, we provide an overview of the evidence regarding chemokines involvement in COPD, and we hypothesize that a dysregulation of this tightly regulated system is critical in COPD evolution, both at a stable state and during exacerbations. Targeting chemokines and chemokine receptors could be highly attractive as a mean to control both chronic inflammation and bronchial remodeling. We present a special focus on the CXCL8-CXCR1/2, CXCL9/10/11-CXCR3, CCL2-CCR2, and CXCL12-CXCR4 axes that seem particularly involved in the disease pathophysiology.

Advances in Tumor-Stroma Interactions: Emerging Role of Cytokine Network in Colorectal and Pancreatic Cancer

Cytokines are a family of soluble factors (Growth Factors (GFs), chemokines, angiogenic factors, and interferons), which regulate a wide range of mechanisms in both physiological and pathological conditions, such as tumor cell growth and progression, angiogenesis, and metastasis. In recent years, the growing interest in developing new cancer targeted therapies has been accompanied by the effort to characterize Tumor Microenvironment (TME) and Tumor-Stroma Interactions (TSI). The connection between tumor and stroma is now well established and, in the last decade, evidence from genetic, pharmacological, and epidemiological data supported the importance of microenvironment in tumor progression. However, several of the mechanisms behind TSI and their implication in tumor progression remain still unclear and it is crucial to establish their potential in determining pharmacological response. Many studies have demonstrated that cytokines network can profoundly affect TME, thus displaying potential therapeutic efficacy in both preclinical and clinical models. The goal of this review is to give an overview of the most relevant cytokines involved in colorectal and pancreatic cancer progression and their implication in drug response.

Radionuclide-Labeled Peptides for Imaging and Treatment of CXCR4- Overexpressing Malignant Tumors

Malignant tumors are a major cause of death. The lack of methods that provide an early diagnosis and adequate treatment of cancers is the main obstacle to precision medicine. The C-X-C chemokine receptor 4 (CXCR4) is overexpressed in various tumors and plays a key role in tumor pathogenesis. Therefore, CXCR4-targeted molecular imaging can quickly and accurately detect and quantify CXCR4 abnormalities in real time. The expression level and activation status of CXCR4 are very important for screening susceptible populations and providing an accurate diagnosis and optimal treatment. In view of the fact that radionuclide-labeled peptides have become widely used for the diagnosis and treatment of tumors, this manuscript reviews the potential of different radionuclide-labeled peptide inhibitors for the targeted imaging of CXCR4- positive tumors and targeted treatment. The article also discusses the specificity and in vivo distribution of radionuclide-labeled peptide inhibitors, and translation of these inhibitors to the clinic.

Microvesicles of osteoblasts modulate bone marrow mesenchymal stem cell-induced apoptosis to curcumin in myeloid leukemia cells

Microvesicles (MVs) derived from bone marrow niche components have an important role in genetic reprogramming and subsequent drugs induce apoptosis in leukemic cells. Here, we have found that undertreatment of curcumin or daunorubicin, the cross-talk through MVs of KG-1-bone marrow mesenchymal stem cells (BMSCs), significantly downregulates the expression of the survival gene osteopontin (OPN), CXCL-12, IL-6 (interleukin-6), STAT-3, and VCAM-1 (vascular cell adhesion molecule 1) in treated-KG-1 cells as well as exclusively upregulates CXCL-12 in BMSCs. Drug treated-cell populations' MVs of both single cultured osteoblasts (OBs) and cocultured KG-1 + BMSCs + OBs similarly upregulate survival mediators' OPN, CXCL-12, IL-6, STAT-3, and VCAM-1 in treated-KG-1 cells. Likewise, isolated MVs from KG-1 cells or communication between KG-1, BMSCs, and OBs treated by drugs increase the expression of genes OPN, CXCL-12, IL-6, STAT3, and VCAM-1 by OBs. MVs derived from KG-1 + BMSCs + OBs reduce drug-induced apoptosis in KG-1 cells. This suggests MVs-mediated information transfer is a procedure whereby OBs could overcome BMSCs-induced apoptosis in drug-treated-KG-1 cells.

Osteogenic niche in the regulation of normal hematopoiesis and leukemogenesis

The bone marrow microenvironment, also known as the bone marrow niche, is a complex network of cell types and acellular factors that supports normal hematopoiesis. For many years, leukemia was believed to be caused by a series of genetic hits to hematopoietic stem and progenitor cells, which transform them to preleukemic, and eventually to leukemic, cells. Recent discoveries suggest that genetic alterations in bone marrow niche cells, particularly in osteogenic cells, may also cause myeloid leukemia in mouse models. The osteogenic niche, which consists of osteoprogenitors, preosteoblasts, mature osteoblasts, osteocytes and osteoclasts, has been shown to play a critical role in the maintenance and expansion of hematopoietic stem and progenitor cells as well as in their oncogenic transformation into leukemia stem/initiating cells. We have recently shown that acute myeloid leukemia cells induce osteogenic differentiation in mesenchymal stromal cells to gain a growth advantage. In this review, we discuss the role of the osteogenic niche in the maintenance of hematopoietic stem and progenitor cells, as well as in their transformation into leukemia cells. We also discuss the signaling pathways that regulate osteogenic niche-hematopoietic stem and progenitor cells or osteogenic niche-leukemic stem/initiating cell interactions in the bone marrow, together with novel approaches for therapeutically targeting these interactions.

Potential use of compounds from sea cucumbers as MDM2 and CXCR4 inhibitors to control cancer cell growth

Ineffectiveness of cancer therapy may originate in the incompatibility of the treatment with various mutations in the cancer cells. Finding novel anticancer treatments that work efficiently for varying types of cancer cells remains challenging. Previous studies have identified that compounds in sea cucumbers are capable of inhibiting the growth of cancer cells and inducing apoptosis. However, information on the underlying mechanisms controlling cancer cell growth at a molecular level remains limited. The current study analyzed the potential of colochiroside A, ds-echinoside A, philinopside E, sphingosine and stichoposide C as inhibitors for anticancer target proteins, including mouse double minute 2 homolog (MDM2) and C-X-C chemokine receptor type 4 (CXCR4). Inhibition of MDM2 triggers apoptosis through regulation of tumor protein 53 and CXCR4 inhibition may prevent cancer cell proliferation and growth by affecting the Janus kinase 2/3 signal transducer and activator of transcription signaling pathway and protein tyrosine kinase 2. The results of a binding affinity analysis using molecular docking revealed that philinopside E and ds-echinoside A may inhibit MDM2 and CXCR4. The data suggested that these active compounds may be promising inhibitors of cell growth by binding to two targets simultaneously. Furthermore, stichoposide C and colochiroside A were predicted to inhibit CXCR4. Additional research is needed to validate the in vitro activity of the aforementioned compounds.

Tissue-Nonspecific Alkaline Phosphatase Is Required for MC3T3 Osteoblast-Mediated Protection of Acute Myeloid Leukemia Cells from Apoptosis

The bone marrow microenvironment harbors and protects leukemic cells from apoptosis-inducing agents via mechanisms that are incompletely understood. We previously showed SDF-1 (CXCL-12), a chemokine readily abundant within the bone marrow microenvironment, induces apoptosis in acute myeloid leukemia (AML) cells that express high levels of the SDF-1 receptor CXCR4. However, differentiating osteoblasts found within this niche protect cocultured AML cells from apoptosis. Additionally, this protection was abrogated upon treatment of the differentiating osteoblasts with histone deacetylase inhibitors (HDACi). In this study, we begin to characterize and target the molecular mechanisms that mediate this osteoblast protection. Quantitative RT-PCR revealed that HDACi treatment of differentiating osteoblasts (mouse MC3T3 osteoblast cell line) reduced expression of multiple genes required for osteoblast differentiation, including genes important for producing mineralized bone matrix. Interestingly, pretreating differentiating osteoblasts with cyclosporine A, a drug known to inhibit osteoblast differentiation, similarly impaired osteoblast-mediated protection of cocultured AML cells (KG1a and U937 human AML cell lines). Both HDACi and cyclosporine A reduced osteoblast expression of the key mineralization enzyme tissue-nonspecific alkaline phosphatase (TNAP; encoded by Alpl). Moreover, specifically reducing TNAP expression or activity in differentiating osteoblasts significantly impaired the ability of the osteoblasts to protect cocultured AML cells. Together, our results indicate that inhibiting osteoblast matrix mineralization by specifically targeting TNAP is sufficient to significantly impair osteoblast-mediated protection of AML cells. Therefore, designing combination therapies that additionally target the osteoblast-produced mineralized bone matrix may improve treatment of AML by reducing the protection of leukemic cells within the bone marrow microenvironment.

A combination of an anti-SLAMF6 antibody and ibrutinib efficiently abrogates expansion of chronic lymphocytic leukemia cells

The signaling lymphocyte activation molecule family [SLAMF] of cell surface receptors partakes in both the development of several immunocyte lineages and innate and adaptive immune responses in humans and mice. For instance, the homophilic molecule SLAMF6 (CD352) is in part involved in natural killer T cell development, but also modulates T follicular helper cell and germinal B cell interactions. Here we report that upon transplantation of a well-defined aggressive murine B220⁺CD5⁺ Chronic Lymphocytic Leukemia (CLL) cell clone, TCL1-192, into SCID mice one injection of a monoclonal antibody directed against SLAMF6 (αSlamf6) abrogates tumor progression in the spleen, bone marrow and blood. Similarly, progression of a murine B cell lymphoma, LMP2A/λMyc, was also eliminated by αSlamf6. But, surprisingly, αSLAMF6 neither eliminated TCL1-192 nor LMP2A/λMyc cells, which resided in the peritoneal cavity or omentum. This appeared to be dependent upon the tumor environment, which affected the frequency of sub-populations of the TCL1-192 clone or the inability of peritoneal macrophages to induce Antibody Dependent Cellular Cytotoxicity (ADCC). However, co-administering αSlamf6 with the Bruton tyrosine kinase (Btk) inhibitor, ibrutinib, synergized to efficiently eliminate the tumor cells in the spleen, bone marrow, liver and the peritoneal cavity. Because an anti-human SLAMF6 mAb efficiently killed human CLL cells in vitro and in vivo, we propose that a combination of αSlamf6 with ibrutinib should be considered as a novel therapeutic approach for CLL and other B cell tumors.

CXCR4 Promotes Neuroblastoma Growth and Therapeutic Resistance through miR-15a/16-1-Mediated ERK and BCL2/Cyclin D1 Pathways

CXCR4 expression in neuroblastoma tumors correlates with disease severity. In this study, we describe mechanisms by which CXCR4 signaling controls neuroblastoma tumor growth and response to therapy. We found that overexpression of CXCR4 or stimulation with CXCL12 supports neuroblastoma tumorigenesis. Moreover, CXCR4 inhibition with the high-affinity CXCR4 antagonist BL-8040 prevented tumor growth and reduced survival of tumor cells. These effects were mediated by the upregulation of miR-15a/16-1, which resulted in downregulation of their target genes BCL-2 and cyclin D1, as well as inhibition of ERK. Overexpression of miR-15a/16-1 in cells increased cell death, whereas antagomirs to miR-15a/16-1 abolished the proapoptotic effects of BL-8040. CXCR4 overexpression also increased miR-15a/16-1, shifting their oncogenic dependency from the BCL-2 to the ERK signaling pathway. Overall, our results demonstrate the therapeutic potential of CXCR4 inhibition in neuroblastoma treatment and provide a rationale to test combination therapies employing CXCR4 and BCL-2 inhibitors to increase the efficacy of these agents.Significance: These results provide a mechanistic rationale for combination therapy of CXCR4 and BCL-2 inhibitors to treat a common and commonly aggressive pediatric cancer.Cancer Res; 78(6); 1471-83. ©2017 AACR.

Histone deacetylase inhibitors reduce differentiating osteoblast-mediated protection of acute myeloid leukemia cells from cytarabine

The bone marrow microenvironment protects acute myeloid leukemia (AML) cells during chemotherapy and is a major factor in relapse. Here, we examined which type(s) of bone marrow cells are responsible for the relapse of AML following treatment with cytarabine (Ara-C), and we identified a means to inhibit this protection. To determine the protective cell type(s), AML cells were treated with Ara-C, and AML cell survival in the presence or absence of osteoblast lineage cells was assessed. Cultured AML cells and patient bone marrow isolates were each significantly protected from Ara-C-induced apoptosis by co-culture with differentiating osteoblasts. Moreover, pretreating differentiating osteoblasts with the histone deacetylase inhibitors (HDACi) vorinostat and panobinostat abrogated the ability of the differentiating osteoblasts to protect AML cells. Together, our results indicate that differentiating osteoblasts have the potential to promote residual AML in the bone marrow following standard chemotherapy and act via a mechanism requiring HDACi-sensitive gene expression. Using HDACi to target the leukemic microenvironment in combination with Ara-C could potentially improve treatment of AML. Moreover, other strategies for manipulating bone marrow osteoblasts may also help eradicate AML cells and reduce relapse.

Reciprocal Interactions of Leukemic Cells with Bone Marrow Stromal Cells Promote Enrichment of Leukemic Stem Cell Compartments in Response to Curcumin and Daunorubicin

A predominant challenge in developing curative leukemia therapy is interactions of leukemic cells with the bone marrow stromal microenvironment. We aimed to investigate the role of stromal cells, such as bone marrow mesenchymal stromal cells (BMSCs) and osteoblasts (OBs), in curcumin (CUR) and daunorubicin (DNR) induced apoptosis of acute myeloid leukemia (AML) cells. We used KG1 and U937 as leukemia cell line models and treated them with CUR and DNR. The cells were then co-cultured with BMSCs or a combination of BMSCs and OBs as feeders. After 24 hours of co-culture, BMSCs or OBs were sorted and separated from the leukemia cells and apoptosis levels were analyzed by annexin/propidium iodide (PI) staining on flow cytometry. Potentially involved molecular pathways were analyzed at gene and protein levels by Real time PCR and western blotting, respectively. The results showed AML cells co-cultured with BMSCs plus OBs to be more resistant to drug induced-apoptosis compared to co-culture with BMSCs alone or without co-culture. Expression levels of OPN, CXCL-12, IL-6, STAT-3 and VCAM-1 were also significantly up-regulated in OBs and AML cells, at both mRNA and protein levels after co-culture, with concurrent enrichment of CD34+ AML cells. Our data showed, in a stromal cell niche-based model, that OBs revoke the influence of BMSCs on leukemic cells and promote enrichment of both CD34+ and CD34- leukemic stem cell (LSC) compartments in response to CUR and DNR. Up-regulation of OPN, CXCL-12, IL-6, STAT-3 and VCAM-1 in OBs and AML cells in co-culture might be part of molecular mechanisms that block CUR or CUR+DNR-induced apoptosis and promote enrichment of CD34+ and CD34- LSCs.

lncRNA co-expression network model for the prognostic analysis of acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly heterogeneous hematologic malignancy with great variability of prognostic behaviors. Previous studies have reported that long non-coding RNAs (lncRNAs) play an important role in AML and may thus be used as potential prognostic biomarkers. However, thus use of lncRNAs as prognostic biomarkers in AML and their detailed mechanisms of action in this disease have not yet been well characterized. For this purpose, in the present study, the expression levels of lncRNAs and mRNAs were calculated using the RNA-seq V2 data for AML, following which a lncRNA-lncRNA co-expression network (LLCN) was constructed. This revealed a total of 8 AML prognosis-related lncRNA modules were identified, which displayed a significant correlation with patient survival (p≤0.05). Subsequently, a prognosis-related lncRNA module pathway network was constructed to interpret the functional mechanism of the prognostic modules in AML. The results indicated that these prognostic modules were involved in the AML pathway, chemokine signaling pathway and WNT signaling pathway, all of which play important roles in AML. Furthermore, the investigation of lncRNAs in these prognostic modules suggested that an lncRNA (ZNF571-AS1) may be involved in AML via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway by regulating KIT and STAT5. The results of the present study not only provide potential lncRNA modules as prognostic biomarkers, but also provide further insight into the molecular mechanisms of action of lncRNAs.

Chemokine Receptor Signaling and the Hallmarks of Cancer

The chemokines are a family of chemotactic cytokines that mediate their activity by acting on seven-transmembrane-spanning G protein-coupled receptors. Both the ability of the chemokines and their receptors to form homo- and heterodimers and the promiscuity of the chemokine-chemokine receptor interaction endow this protein family with enormous signaling plasticity and complexity that are not fully understood at present. Chemokines were initially identified as essential regulators of homeostatic and inflammatory trafficking of innate and adaptive leucocytes from lymphoid organs to tissues. Chemokines also mediate the host response to cancer. Nevertheless, chemokine function in this response is not limited to regulating leucocyte infiltration into the tumor microenvironment. It is now known that chemokines and their receptors influence most-if not all-hallmark processes of cancer; they act on both neoplastic and untransformed cells in the tumor microenvironment, including fibroblasts, endothelial cells (blood and lymphatic), bone marrow-derived stem cells, and, obviously, infiltrating leucocytes. This review begins with an overview of chemokine and chemokine receptor structure, to better define how chemokines affect the proliferation, survival, stemness, and metastatic potential of neoplastic cells. We also examine the main mechanisms by which chemokines regulate tumor angiogenesis and immune cell infiltration, emphasizing the pro- and antitumorigenic activity of this protein superfamily in these interrelated processes.

Diagnostic Flow Cytometry and the AIDS Pandemic

The onset of the AIDS pandemic in the early 1980s coincided with the convergence of technologies now collectively known as flow cytometry (FCM). Major advances in FCM led significantly toward our understanding of the pathogenicity of the disease, which in turn led to wider adoption of the technology, including using it effectively in a variety of diagnostics. CD4+ T lymphocyte population counts, along with human immunodeficiency virus (HIV) viral load, remain the gold standard in diagnosis and continue to play a major role in the monitoring of advanced retroviral therapies. Arguably, the spread of AIDS (acquired immunodeficiency syndrome), the HIV virus, and the toll of the virus on humanity have been considerably altered by the concurrent development of FCM, the details of which are presented herein.

Molecular dissection of valproic acid effects in acute myeloid leukemia identifies predictive networks

Histone deacetylase inhibitors (HDACIs) like valproic acid (VPA) display activity in leukemia models and induce tumor-selective cytotoxicity against acute myeloid leukemia (AML) blasts. As there are limited data on HDACIs effects, we aimed to dissect VPA effects in vitro using myeloid cell lines with the idea to integrate findings with in vivo data from AML patients treated with VPA additionally to intensive chemotherapy (n = 12). By gene expression profiling we identified an in vitro VPA response signature enriched for genes/pathways known to be implicated in cell cycle arrest, apoptosis, and DNA repair. Following VPA treatment in vivo, gene expression changes in AML patients showed concordant results with the in vitro VPA response despite concomitant intensive chemotherapy. Comparative miRNA profiling revealed VPA-associated miRNA expression changes likely contributing to a VPA-induced reversion of deregulated gene expression. In addition, we were able to define markers predicting VPA response in vivo such as CXCR4 and LBH. These could be validated in an independent cohort of VPA and intensive chemotherapy treated AML patients (n = 114) in which they were inversely correlated with relapse-free survival. In summary, our data provide new insights into the molecular mechanisms of VPA in myeloid blasts, which might be useful in further advancing HDAC inhibition based treatment approaches in AML.

Targeted positron emission tomography imaging of CXCR4 expression in patients with acute myeloid leukemia

Acute myeloid leukemia originates from leukemia-initiating cells that reside in the protective bone marrow niche. CXCR4/CXCL12 interaction is crucially involved in recruitment and retention of leukemia-initiating cells within this niche. Various drugs targeting this pathway have entered clinical trials. To evaluate CXCR4 imaging in acute myeloid leukemia, we first tested CXCR4 expression in patient-derived primary blasts. Flow cytometry revealed that high blast counts in patients with acute myeloid leukemia correlate with high CXCR4 expression. The wide range of CXCR4 surface expression in patients was reflected in cell lines of acute myeloid leukemia. Next, we evaluated the CXCR4-specific peptide Pentixafor by positron emission tomography imaging in mice harboring CXCR4 positive and CXCR4 negative leukemia xenografts, and in 10 patients with active disease. [(68)Ga]Pentixafor-positron emission tomography showed specific measurable disease in murine CXCR4 positive xenografts, but not when CXCR4 was knocked out with CRISPR/Cas9 gene editing. Five of 10 patients showed tracer uptake correlating well with leukemia infiltration assessed by magnetic resonance imaging. The mean maximal standard uptake value was significantly higher in visually CXCR4 positive patients compared to CXCR4 negative patients. In summary, in vivo molecular CXCR4 imaging by means of positron emission tomography is feasible in acute myeloid leukemia. These data provide a framework for future diagnostic and theranostic approaches targeting the CXCR4/CXCL12-defined leukemia-initiating cell niche.

MCL-1 is the key target of adjuvant chemotherapy to reverse the cisplatin-resistance in NSCLC

Cisplatin is one of the most effective chemotherapeutic agents for the treatment of lung cancer. However, the acquired resistance occurred in cancer cells limits the clinical application of cisplatin. MCL-1, which is an important member in the pro-survival Bcl-2 family, plays a critical role in multidrug resistance (MDR). The aim of the present study is to investigate the value of Pan-Bcl-2 inhibitor as sensitizer for the chemotherapy of cisplatin-resistant non-small cell lung cancer (NSCLC) cells. We found the obatoclax but not the ABT-737 significantly decreased the IC50 (half maximal inhibitory concentration) of cisplatin in cisplatin-resistant NSCLC cells. Furthermore, we demonstrated that the mechanism of obatoclax-promoted cell death induced by cisplatin was dependent on the inhibition of MCL-1, which couldn't be inhibited by ABT-737 but is the target of obatoclax. Moreover, inhibition of MCL-1 recovered the function of NOXA and BAK in cisplatin-resistant NSCLC cells, leading to the promotion of mitochondrial apoptosis induced by cisplatin. Interestingly, our date indicated the obatoclax also reversed the cross-resistance in cisplatin-resistant NSCLC cells. Therefore, we demonstrated that the targeted therapy with MCL-1 inhibitors, such as obatoclax, may represent a novel strategy for cancer therapy.

Targeting the microenvironment in acute myeloid leukemia

The bone marrow microenvironment plays a critical role in the development, progression, and relapse of acute myeloid leukemia (AML). Similar to normal hematopoietic stem cells, AML blasts express receptors on their surface, allowing them to interact with specific components of the marrow microenvironment. These interactions contribute to both chemotherapy resistance and disease relapse. Preclinical studies and early phase clinical trials have demonstrated the potential for targeting the tumor-microenvironment interactions in AML. Agents currently under investigation include hypoxia-inducible agents and inhibitors of CXCR4 and adhesion molecules such as VLA-4 and E-selectin.

Targeting the leukemia-stroma interaction in acute myeloid leukemia: rationale and latest evidence

The concept of 'niche' has become a focus of attention in hematologic malignancies including acute myeloid leukemia (AML). Similar to normal hematopoietic stem cells, AML cells interact both anatomically and functionally with the stroma within the marrow microenvironment. These interactions have a critical role in the development, progression, and relapse of AML. Chemotherapy resistance is another feature that is at least partially related to AML-stroma interactions. The evidence for safety and efficacy of agents targeting AML-niche interactions is currently limited to preclinical and early phase clinical studies. Examples include CXCR4 inhibitors, hypoxia-inducible agents, and adhesion molecule inhibitors. Agents that target AML-stroma interactions differ from mutation-specific approaches that tend to be limited due to within-individual and between-individual genetic heterogeneity. These agents may be used alone or as chemosensitizers in AML. This novel and rapidly advancing strategy is likely to become an important part of our armamentarium of anti-leukemia treatments in the near future.

Imiquimod-induced apoptosis of melanoma cells is mediated by ER stress-dependent Noxa induction and enhanced by NF-κB inhibition

Melanoma is characterized by dysregulated intracellular signalling pathways including an impairment of the cell death machinery, ultimately resulting in melanoma resistance, survival and progression. This explains the tumour's extraordinary resistance to the standard treatment. Imiquimod is a topical immune response modifier (imidazoquinoline) with both antiviral and antitumour activities. The mechanism by which imiquimod triggers the apoptosis of melanoma cells has now been carefully elucidated. Imiquimod‐induced apoptosis is associated with the activation of apoptosis signalling regulating kinase1/c‐Jun‐N‐terminal kinase/p38 pathways and the induction of endoplasmic stress characterized by the activation of the protein kinase RNA‐like endoplasmic reticulum kinase signalling pathway, increase in intracellular Ca²⁺ release, degradation of calpain and subsequent cleavage of caspase‐4. Moreover, imiquimod triggers the activation of NF‐κB and the expression of the inhibitor of apoptosis proteins (IAPs) such as, X‐linked IAP (XIAP) together with the accumulation of reactive oxygen species (ROS). Also, imiquimod triggers mitochondrial dysregulation characterized by the loss of mitochondrial membrane potential (Δψm), the increase in cytochrome c release, and cleavage of caspase‐9, caspase‐3 and poly(ADP‐ribose) polymerase (PARP). Inhibitors of specific pathways, permit the elucidation of possible mechanisms of imiquimod‐induced apoptosis. They demonstrate that inhibition of NF‐kB by the inhibitor of nuclear factor kappa‐B kinase (IKK) inhibitor Bay 11‐782 or knockdown of XIAP induces melanoma apoptosis in cells exposed to imiquimod. These findings support the use of either IKK inhibitors or IAP antagonists as adjuvant therapies to improve the effectiveness topical imiquimod in the treatment of melanoma.

Histone Deacetylase Inhibitors Target the Leukemic Microenvironment by Enhancing a Nherf1-Protein Phosphatase 1α-TAZ Signaling Pathway in Osteoblasts

Disrupting the protective signals provided by the bone marrow microenvironment will be critical for more effective combination drug therapies for acute myeloid leukemia (AML). Cells of the osteoblast lineage that reside in the endosteal niche have been implicated in promoting survival of AML cells. Here, we investigated how to prevent this protective interaction. We previously showed that SDF-1, a chemokine abundant in the bone marrow, induces apoptosis of AML cells, unless the leukemic cells receive protective signals provided by differentiating osteoblasts (8, 10). We now identify a novel signaling pathway in differentiating osteoblasts that can be manipulated to disrupt the osteoblast-mediated protection of AML cells. Treating differentiating osteoblasts with histone deacetylase inhibitors (HDACi) abrogated their ability to protect co-cultured AML cells from SDF-1-induced apoptosis. HDACi prominently up-regulated expression of the Nherf1 scaffold protein, which played a major role in preventing osteoblast-mediated protection of AML cells. Protein phosphatase-1α (PP1α) was identified as a novel Nherf1 interacting protein that acts as the downstream mediator of this response by promoting nuclear localization of the TAZ transcriptional modulator. Moreover, independent activation of either PP1α or TAZ was sufficient to prevent osteoblast-mediated protection of AML cells even in the absence of HDACi. Together, these results indicate that HDACi target the AML microenvironment by enhancing activation of the Nherf1-PP1α-TAZ pathway in osteoblasts. Selective drug targeting of this osteoblast signaling pathway may improve treatments of AML by rendering leukemic cells in the bone marrow more susceptible to apoptosis.

A CXCR4 antagonist leads to tumor suppression by activation of immune cells in a leukemia-induced microenvironment

The bone marrow microenvironment (BMM) provides a protective niche that supports growth and survival of normal and leukemic hematopoietic stem cells. The SDF-1/CXCR4 interaction is critical for regulation of homing to and retention of hematopoietic cells in the bone marrow (BM), which leads to increased chemoresistance. SDF-1/CXCR4 plays pivotal roles in cross-interactions between blasts and the BMM to prevent retention and mobilization of leukemic cells, as well as in normal hematopoiesis including the development of immune cells. We show that the CXCR4 antagonist, plerixafor, decreased the level of CXCR4 expression and inhibited SDF-1-induced migration of leukemic cells. Further, the inhibition of the interaction between leukemic cells and the BMM by the plerixafor enhanced cytotoxic activity of immune cells as a result of increased susceptibility of leukemic cells to chemotherapeutic agents such as cytosine arabinoside (Ara-C) in a mouse model of acute myeloid leukemia (AML), suggesting biological effects of the BMM through immune cell activation. Because alterations in the BMM promote retention and survival of leukemic cells, targeting the niche is regarded as an advanced strategy to eradicate drug-resistant leukemic blasts. This study demonstrates that the effects of CXCR4 inhibition on blast suppression and immune cell function in the tumor microenvironment and chemotherapy with plerixafor represents an advanced therapeutic strategy of targeting the leukemic niche.

Emerging therapeutic targets for the treatment of human acute myeloid leukemia (part 1) - gene transcription, cell cycle regulation, metabolism and intercellular communication

Human acute myeloid leukemia is a heterogeneous disease and the effect of therapeutic targeting of specific molecular mechanisms will probably vary between patient subsets. Cell cycle regulators are among the emerging targets (e.g., aurora and polo-like kinases, cyclin-dependent kinases). Inhibition of communication between acute myeloid leukemia and stromal cells is also considered; among the most promising of these strategies are inhibition of hedgehog-initiated, CXCR4-CXCL12 and Axl-Gas6 signaling. Finally, targeting of energy and protein metabolism is considered, the most promising strategy being inhibition of isocitrate dehydrogenase in patients with IDH mutations. Thus, several strategies are now considered, and a major common challenge for all of them is to clarify how they should be combined with each other or with conventional chemotherapy, and whether their use should be limited to certain subsets of patients.

Activation of p38 MAPK-regulated Bcl-xL signaling increases survival against zoledronic acid-induced apoptosis in osteoclast precursors

The nitrogen-containing bisphosphonate zoledronic acid (ZA) induces apoptosis in osteoclasts and inhibits osteoclast-mediated bone resorption. It is widely used to treat osteoporosis. However, some patients are less responsive to ZA treatment, and the mechanisms of resistance are still unclear. Here, we identified that murine osteoclast precursors may develop resistance to ZA-induced apoptosis. These resistant cells survived the apoptotic effect of ZA following an increase in anti-apoptotic Bcl-xL. Pharmacologically inhibiting Bcl-xL facilitated ZA-induced apoptosis. Treatment with ZA activated p38 MAPK, increasing Bcl-xL expression and cell survival. Nuclear import of β-catenin regulated by p38 MAPK determined Bcl-xL mRNA expression and cell survival in response to ZA. ZA also inactivated glycogen synthase kinase (GSK)-3β, a negative upstream regulator of β-catenin, in a p38 MAPK-mediated manner. Synergistic pharmacological inhibition of p38 MAPK with ZA attenuated receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast differentiation and facilitated ZA-induced apoptosis. These results demonstrate that elevated Bcl-xL expression mediated by p38 MAPK-regulated GSK-3β/β-catenin signaling is required for cell survival of ZA-induced apoptosis in both osteoclast precursors and osteoclasts. Finally, we demonstrated that inhibiting p38 MAPK-mediated pathway enhanced ZA effect on increasing the bone mineral density of ovariectomized mice. This result suggests that targeting these pathways may represent a potential therapeutic strategy.

Osteoblasts protect AML cells from SDF-1-induced apoptosis

The bone marrow provides a protective environment for acute myeloid leukemia (AML) cells that often allows leukemic stem cells to survive standard chemotherapeutic regimens. Targeting these leukemic stem cells within the bone marrow is critical for preventing relapse. We recently demonstrated that SDF-1, a chemokine abundant in the bone marrow, induces apoptosis in AML cell lines and in patient samples expressing high levels of its receptor, CXCR4. Here we show that a subset of osteoblast lineage cells within the bone marrow can protect AML cells from undergoing apoptosis in response to the SDF-1 naturally present in that location. In co-culture systems, osteoblasts at various stages of differentiation protected AML cell lines and patient isolates from SDF-1-induced apoptosis. The differentiation of the osteoblast cell lines, MC3T3 and W-20-17, mediated this protection via a cell contact-independent mechanism. In contrast, bone marrow-derived mesenchymal cells, the precursors of osteoblasts, induced apoptosis in AML cells via a CXCR4-dependent mechanism and failed to protect AML cells from exogenously added SDF-1. These results indicate that osteoblasts in the process of differentiation potently inhibit the SDF-1-driven apoptotic pathway of CXCR4-expressing AML cells residing in the bone marrow. Drugs targeting this protective mechanism could potentially provide a new approach to treating AML by enhancing the SDF-1-induced apoptosis of AML cells residing within the bone marrow microenvironment.