CXCR2 macromolecular complex in pancreatic cancer: a potential therapeutic target in tumor growth

The roles of phospholipase C-β related signals in the proliferation, metastasis and angiogenesis of malignant tumors, and the corresponding protective measures

PLC-β is widely distributed in eukaryotic cells and is the key enzyme in phosphatidylinositol signal transduction pathway. The cellular functions regulated by its four subtypes (PLC-β1, PLC-β2, PLC-β3, PLC-β4) play an important role in maintaining homeostasis of organism. PLC-β and its related signals can promote or inhibit the occurrence and development of cancer by affecting the growth, differentiation and metastasis of cells, while targeted intervention of PLC-β1-PI3K-AKT, PLC-β2/CD133, CXCR2-NHERF1-PLC-β3, Gαq-PLC-β4-PKC-MAPK and so on can provide new strategies for the precise prevention and treatment of malignant tumors. This paper reviews the mechanism of PLC-β in various tumor cells from four aspects: proliferation and differentiation, invasion and metastasis, angiogenesis and protective measures.

Small molecule antagonist of CXCR2 and CXCR1 inhibits tumor growth, angiogenesis, and metastasis in pancreatic cancer

Pancreatic cancer (PC) has a poor prognosis, and current therapeutic strategies are ineffective in advanced diseases. We and others have shown the aberrant expression of CXCR2 and its ligands in PC development and progression. Our objective for this study was to evaluate the therapeutic utility of CXCR2/1 targeting using an small molecule antagonist, SCH-479833, in different PC preclinical murine models (syngeneic or xenogeneic). Our results demonstrate that CXCR2/1 antagonist had both antitumor and anti-metastatic effects in PC. CXCR2/1 antagonist treatment inhibited tumor cell proliferation, migration, angiogenesis, and recruitment of neutrophils, while it increased apoptosis. Treatment with the antagonist enhanced fibrosis, tumor necrosis, and extramedullary hematopoiesis. Together, these findings suggest that selectively targeting CXCR2/1 with small molecule inhibitors is a promising therapeutic approach for inhibiting PC growth, angiogenesis, and metastasis.

Radiocontrast agent and intraductal pressure promote the progression of post-ERCP pancreatitis by regulating inflammatory response, cellular apoptosis, and tight junction integrity

OBJECTIVE

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is the most common complication following ERCP and the mechanism is not fully understood. This study evaluated the changes in the inflammatory response, cellular apoptosis, and tight junction integrity in a rat model of pancreatitis to explore the underlying mechanism.

METHODS

PEP was induced in rats by retrograde biliopancreatic ductal infusion of contrast agents or saline. Pancreatic tissues were harvested and evaluated by histopathologic, immunohistochemical, immunofluorescence, and Western blot analyses. In addition, amylase and proinflammatory cytokines in plasma were quantified by ELISA assay.

RESULTS

PEP rats developed more severe acute pancreatitis than the sham group after injection of the contrast agent or isotonic saline. PEP rats exhibited increased tissue damage, plasma amylase, proinflammatory cytokines, necrosis, inflammatory infiltrates, apoptosis, and tight junction disruption. At the molecular level, contrast agent and isotonic saline-injected PEP rats demonstrated elevated NF-κB p65 and STAT3 pathways activation, altered expression and activation of apoptosis-related proteins, and suppressed expression of tight junction molecules. However, the contrast agent concentration had no effect on these changes.

CONCLUSIONS

In models of acute pancreatitis induced using contrast agent and hydrostatic pressure, the contrast agent and high hydrostatic pressure easily induced the inflammatory response, apoptosis, and tight junction disruption. It is noteworthy that no significant difference in damaged pancreatic acinar cells was observed with different concentrations of the contrast agent.

LINC00337 promotes tumor angiogenesis in colorectal cancer by recruiting DNMT1, which suppresses the expression of CNN1

Colorectal cancer (CRC) is one of the most common human malignancies. An increasing body of evidence has revealed the important roles long noncoding RNA (lncRNA) plays in the growth dynamics of CRC cells. In this study, we aimed to define the role of LINC00337 in the malignant phenotypes, especially angiogenesis, of CRC and clarify the underlying molecular basis. Bioinformatic analyses identified promoter region methylation of CNN1 in CRC, which was further validated by BSP and MSP assays. Loss- and gain- of function approaches were used to determine the roles of CNN1 and LINC00337 in vitro and in vivo. MTT-based method, Transwell migration/invasion assays, and tube formation assay were adopted to evaluate the cancer cell proliferation, migration/invasion, and proangiogenetic potency respectively in vitro. The tumor growth, microvascular density (MVD) and markers of proliferation (Ki67) and angiogenesis (VEGF) were quantified in nude mice xenografted with CRC cells. It was found that CNN1 downregulation and LINC00337 overexpression occurred in CRC tissues and cells. Besides, the CNN1 promoter region was hypermethylated in CRC. CNN1 overexpression or LINC00337 knockdown restricted CRC cell proliferation, migration/invasion, and proangiogenetic potency in vitro, which was substantiated by the in vivo experiments evidenced by facilitated tumor growth and MVD as well as elevated Ki67 and VEGF. Furthermore, our mechanistic evidence revealed that LINC00337 recruited DNMT1 to the promoter region of CNN1 and restricted the transcription of CNN1. Taken together, this study indicates that LINC00337 facilitates the tumorigenesis and angiogenesis in CRC via recruiting DNMT1 to inhibit the expression of CNN1.

Peptide Targeting of PDZ-Dependent Interactions as Pharmacological Intervention in Immune-Related Diseases

PDZ (postsynaptic density (PSD95), discs large (Dlg), and zonula occludens (ZO-1)-dependent interactions are widely distributed within different cell types and regulate a variety of cellular processes. To date, some of these interactions have been identified as targets of small molecules or peptides, mainly related to central nervous system disorders and cancer. Recently, the knowledge of PDZ proteins and their interactions has been extended to various cell types of the immune system, suggesting that their targeting by viral pathogens may constitute an immune evasion mechanism that favors viral replication and dissemination. Thus, the pharmacological modulation of these interactions, either with small molecules or peptides, could help in the control of some immune-related diseases. Deeper structural and functional knowledge of this kind of protein–protein interactions, especially in immune cells, will uncover novel pharmacological targets for a diversity of clinical conditions.

Chemokine Receptor 2 (CXCR2) Gene Polymorphisms and Their Association with the Risk of Developing Peri-Implantitis in Chinese Han Population

Purpose

This study aimed to investigate the role of chemokine receptor 2 (CXCR2) gene polymorphisms in peri-implantitis susceptibility in a Chinese Han population.

Patients and Methods

A total of 260 individuals were included in this study, including 127 peri-implantitis patients and 133 healthy implants. CXCR2 gene rs2230054 and rs1126580 polymorphisms in different groups were analyzed by the Chi-square test. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were employed to evaluate the association between CXCR2 polymorphism and peri-implantitis susceptibility.

Results

The CT genotype of rs2230054 and the AG genotype and G allele of rs1126580 significantly increased in peri-implantitis patients compared with healthy implants (P < 0.05). The CT genotype of rs2230054 (OR = 1.825, 95% CI = 1.028–3.239) and the AG genotype of rs1126580 (OR = 2.223, 95% CI 1.272–3.885) carriers had a high risk to infect with peri-implantitis. Additionally, these CXCR2 gene polymorphisms have been revealed to be associated with the periodontal status of peri-implantitis patients.

Conclusion

The CXCR2 gene rs2230054 and rs1126580 polymorphisms were associated with the peri-implantitis susceptibility in the Chinese Han population. The CT genotype of rs2230054 and the AG genotype and G allele of rs1126580 serve as risk factors for the occurrence of peri-implantitis.

Host Cxcr2-Dependent Regulation of Pancreatic Cancer Growth, Angiogenesis, and Metastasis

Pancreatic ductal adenocarcinoma (PDAC) manifests aggressive tumor growth and early metastasis. Crucial steps in tumor growth and metastasis are survival, angiogenesis, invasion, and immunosuppression. Our prior research showed that chemokine CXC- receptor-2 (CXCR2) is expressed on endothelial cells, innate immune cells, and fibroblasts, and regulates angiogenesis and immune responses. Here, we examined whether tumor angiogenesis, growth, and metastasis of CXCR2 ligands expressing PDAC cells are regulated in vivo by a host CXCR2-dependent mechanism. C57BL6 Cxcr2-/- mice were generated following crosses between Cxcr2-/+ female and Cxcr2-/- male. Cxcr2 ligands expressing Kirsten rat sarcoma (KRAS-PDAC) cells were orthotopically implanted in the pancreas of wild-type or Cxcr2-/- C57BL6 mice. No significant difference in PDAC tumor growth was observed. Host Cxcr2 loss led to an inhibition in microvessel density in PDAC tumors. Interestingly, an enhanced spontaneous and experimental liver metastasis was observed in Cxcr2-/- mice compared with wild-type mice. Increased metastasis in Cxcr2-/- mice was associated with an increase in extramedullary hematopoiesis and expansion of neutrophils and immature myeloid precursor cells in the spleen of tumor-bearing mice. These data suggest a dynamic role of host CXCR2 axis in regulating tumor immune suppression, tumor growth, and metastasis.

Human umbilical vein endothelial cells-derived microRNA-203-containing extracellular vesicles alleviate non-small-cell lung cancer progression through modulating the DTL/p21 axis

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, and is characterized by extensive metastasis and poor prognosis. Extracellular vesicles (EVs) derived from endothelial cells carrying microRNAs (miRNAs/miRs) have diagnostic and therapeutic potential for NSCLC. We herein investigate the potential of EVs derived from human umbilical vein endothelial cells (HUVECs) to transfer miR-203 to affect the progression of NSCLC. miR-203 and p21 were poorly expressed while DTL was highly expressed both in NSCLC tissues and cell lines. We employed CCK-8 proliferation, colony formation, and Transwell migration and invasion assays to evaluate the effects of miR-203 on NSCLC cell behaviors using loss- and gain-function approaches. EVs were isolated from HUVECs and then co-cultured with the A549 cells transfected with mimic-NC or miR-203 inhibitor. miR-203 targeted DTL and downregulated its expression, subsequently leading to increased stability of p21 which is a tumor suppressor. EV-enriched miR-203 from HUVECs suppressed malignant phenotypes of NSCLC cells and delayed tumor growth. In conclusion, miR-203 from HUVEC-derived EVs exerts inhibitory effects on the progression of NSCLC by targeting DTL and promoting p21 protein stability.

Reduction of miR-744 delivered by NSCLC cell-derived extracellular vesicles upregulates SUV39H1 to promote NSCLC progression via activation of the Smad9/BMP9 axis

Background

Non-small cell lung cancer (NSCLC) is a common type of lung cancer. Extracellular vehicles (EVs) are nano-sized particles containing proteins, lipids, and miRNAs secreted by various cells, which play important roles in the development of lung cancer by regulating a wide range of signaling pathways. This study focused on elucidating a potential mechanism by which EVs promote the development of NSCLC.

Methods

Expression levels of miR-744, SUV39H1, Smad9, and BMP4 in clinical tissue samples of NSCLC patients and cell lines were quantified by RT-qPCR and/or western blot analysis. The interaction between SUV39H1 and miR-744 was identified by dual-luciferase reporter assay. miR-744, SUV39H1, and BMP4 expression levels were modulated in A549 and H460 cells, in order to evaluate their effects on cell proliferation, colony formation and cell cycle. A NSCLC xenograft mouse model was used to verify the in vitro findings. NSCLC cell-derived EVs and normal bronchial epithelial cell-derived EVs were isolated and their roles in NSCLC development were evaluated in vivo and in vitro.

Results

miR-744 expression was lower in cancer cell-derived derived EVs than in normal lung epithelial cell-derived EVs. Reduced miR-744 expression in EVs upregulated SUV39H1 in NSCLC cells and further increased BMP4 levels to promote NSCLC development. BMP4 was upregulated in NSCLC cells upon suppression of Smad9 mediated by SUV39H1. Reduced miR-744 expression transferred from cancer cell-derived EVs into NSCLC cells enhanced cancer development.

Conclusion

Overall, our findings unveiled a mechanism whereby miR-744 delivered by NSCLC-derived EVs upregulated SUV39H1, activating the Smad9/BMP9 axis and thus promoted cancer development.

Intermittent hypoxia-induced downregulation of microRNA-320b promotes lung cancer tumorigenesis by increasing CDT1 via USP37

Obstructive sleep apnea-hypopnea (OSAH) is correlated with an increased incidence of lung cancer. In our study, we explored the functional roles of microRNAs (miRNAs) in lung cancer patients that were complicated with OSAH involving the deubiquitination enzyme. The miR-320b expression pattern in lung cancer tissues and cells was determined. The interactions between ubiquitin-specific peptidase 37 (USP37) and miR-320b were evaluated by a dual-luciferase reporter gene assay, whereas USP37 and Cdc10-dependent transcript 1 (CDT1) was assessed by co-immunoprecipitation and immunofluorescence. After the induction of intermittent hypoxia (IH), a gain-of function approach was performed to investigate roles of miR-320b, USP37, and CDT1 in lung cancer cell proliferation and invasion. In addition, nude mouse xenograft models were used to study their effects on tumor growth in vivo. miR-320b was poorly expressed in lung cancer patients with OSAH. IH treatment downregulated the expression of miR-320b but promoted the proliferation and invasion capabilities of lung cancer cells, both of which were suppressed by the overexpression of miR-320b through decreasing USP37. USP37 interacted with and deubiquitinated CDT1 to protect it from proteasomal degradation. Our study uncovered that IH-induced downregulation of miR-320b promoted the tumorigenesis of lung cancer by the USP37-mediated deubiquitination of CDT1.

Methylation-Mediated Silencing of MicroRNA-497 Promotes Breast Cancer Progression Through Up-Regulation of Mucin1

Background

Potential anti-tumor effects of microRNA-497 (miR-497) have been highlighted in various malignancies including breast cancer. However, little is known about the function of miR-497 and its putative target mucin1 (MUC1) in breast cancer. The present study explored how miR-497 regulates breast cancer progression in a MUC1-dependent manner.

Methods

Expression of miR-497 and MUC1 was determined in breast cancer tissues and cells. Methylation specific polymerase chain reaction was used to measure the methylation status of CpG islands of miR-497 promoter, while chromatin immunoprecipitation assay was used to detect recruitment of methyltransferase to the promoter region of miR-497. Alteration in expression of miR-497 (overexpression) and MUC1 (up- and down-regulation) was performed to examine their roles in breast cancer biology in vitro and in vivo. The binding affinity between miR-497 and MUC1 was investigated through a bioinformatics database and dual luciferase reporter gene assay.

Results

MiR-497 was down-regulated and MUC1 was up-regulated in breast cancer tissues and cell lines. Besides, methylation induced a down-regulation of miR-497 in breast cancer. The bioinformatics analysis and dual luciferase reporter gene assay indicated that miR-497 targeted MUC1. Overexpression of miR-497 inhibited breast cancer cell proliferation and invasion and promoted the apoptosis of breast cancer cells by down-regulating MUC1. The inhibitory action of miR-497 on tumor growth was validated in vivo.

Conclusion

In conclusion, miR-497 down-regulated MUC1 expression and subsequently suppressed breast cancer progression, highlighting miR-497 to be a potential biomarker and therapeutic target for breast cancer therapy.

Host immune genetic variations influence the risk of developing acute myeloid leukaemia: results from the NuCLEAR consortium

The purpose of this study was to conduct a two-stage case control association study including 654 acute myeloid leukaemia (AML) patients and 3477 controls ascertained through the NuCLEAR consortium to evaluate the effect of 27 immune-related single nucleotide polymorphisms (SNPs) on AML risk. In a pooled analysis of cohort studies, we found that carriers of the IL13_rs1295686A/A genotype had an increased risk of AML (P_Corr = 0.0144) whereas carriers of the VEGFA_rs25648T allele had a decreased risk of developing the disease (P_Corr = 0.00086). In addition, we found an association of the IL8_rs2227307 SNP with a decreased risk of developing AML that remained marginally significant after multiple testing (P_Corr = 0.072). Functional experiments suggested that the effect of the IL13_rs1295686 SNP on AML risk might be explained by its role in regulating IL1Ra secretion that modulates AML blast proliferation. Likewise, the protective effect of the IL8_rs2227307 SNP might be mediated by TLR2-mediated immune responses that affect AML blast viability, proliferation and chemorresistance. Despite the potential interest of these results, additional functional studies are still warranted to unravel the mechanisms by which these variants modulate the risk of AML. These findings suggested that IL13, VEGFA and IL8 SNPs play a role in modulating AML risk.

Silencing of long non-coding RNA LINC00520 promotes radiosensitivity of head and neck squamous cell carcinoma cells

Aberrant expression of LINC00520 has been identified in head and neck squamous carcinoma (HNSCC). However, its function in the radiosensitivity of HNSCC remain unclear. Herein, we aimed to define the role LINC00520 in the radiosensitivity of HNSCC and identify the underlying mechanism. Tumour tissues and adjacent normal tissue were collected from HNSCC patients. Differentially expressed genes (DEGs) in HNSCC tumour were obtained from the cancer genome atlas (TCGA) database. Interactions between LINC00520 and miR-195, homeobox A10 (HOXA10) and miR-195 were evaluated by dual-luciferase reporter gene assay, RNA Immunoprecipitation (RIP), and RNA pull-down assay. The effects of LINC00520/miR-195/HOXA10 on radiosensitivity of HNSCC were analysed in the evaluation of radiotherapy outcome. Cell proliferation, invasion, migration, and apoptosis of HNSCC cells were accessed via gain- and loss-of-function approaches. Tumour xenograft in nude mice was conducted in order to confirm the results in vivo. LINC00520 was upregulated while miR-195 was downregulated in HNSCC cells and tissues. Silencing LINC00520 or overexpressing miR-195 promoted radiosensitivity and inhibited cell proliferation, invasion, migration, and apoptosis in HNSCC. Moreover, these in vitro findings were reproduced in vivo in human HNSCC xenograft in nude mice. LINC00520/miR-195/HOXA10 is involved in the radiosensitivity mediation, providing potential therapeutic target for HNSCC treatment.

Long intergenic noncoding RNA 00844 promotes apoptosis and represses proliferation of prostate cancer cells through upregulating GSTP1 by recruiting EBF1

Accumulating evidence have suggested the function of long noncoding RNAs as crucial players in the pathogenesis of prostate cancer (PC), a urologic tumor in male with poor prognosis. This study was designed to explore the functions of long intergenic noncoding RNA 00844 (LINC00844) in PC progression. The expression of LINC00844 and glutathione S-transferase P1-1 (GSTP1) was detected by reverse transcription quantitative polymerase chain reaction, followed by the identification of the relationship among LINC00844, GSTP1, and early B cell factor 1 (EBF1) by dual luciferase reporter gene assay, RNA immunoprecipitation assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay. Using loss- and gain-of-function assays, the effects of LINC00844, GSTP1, and EBF1 on the biological characteristics of PC cells were assessed by cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine assay, and flow cytometry. Lastly, the results from in vitro experiments were verified in vivo by establishing a xenograft tumor model in nude mice. LINC00844 and GSTP1 both displayed low expression in PC tissues and cells. LINC00844 positively regulated the expression of GSTP1 via recruiting EBF1. Overexpression of LINC00844 reduced proliferation and elevated apoptosis of PC cells through recruiting EBF1, which subsequently upregulated GSTP1. In vivo experiments confirmed that LINC00844 or GSTP1 upregulation attenuated tumor growth. LINC00844 elevated GSTP1 expression by recruiting EBF1 to the promoter region of GSTP1, thereby suppressing PC progression. Hence, LINC00844 is a novel therapeutic target for the development of new treatment protocols for PC.

Functions of the CXC ligand family in the pancreatic tumor microenvironment

Therapeutic resistance is the major contributor to the poor prognosis of and low survival from pancreatic cancer (PC). Cancer progression is a complex process reliant on interactions between the tumor and the tumor microenvironment (TME). Members of the CXCL family of chemokines are present in the pancreatic TME and seem to play a vital role in regulating PC progression. As pancreatic tumors interact with the TME and with PC stem cells (CSCs), determining the roles of specific members of the CXCL family is vital to the development of improved therapies. This review highlights the roles of selected CXCLs in the interactions between pancreatic tumor and its stroma, and in CSC phenotypes, which can be used to identify potential treatment targets.

NHERF1 Between Promises and Hopes: Overview on Cancer and Prospective Openings

Na+/H+ exchanger regulatory factor 1 (NHERF1) is a scaffold protein, with two tandem PDZ domains and a carboxyl-terminal ezrin-binding (EB) region. This particular sticky structure is responsible for its interaction with different molecules to form multi-complexes that have a pivotal role in a lot of diseases. In particular, its involvement during carcinogenesis and cancer progression has been deeply analyzed in different tumors. The role of NHERF1 is not unique in cancer; its activity is connected to its subcellular localization. The literature data suggest that NHERF1 could be a new prognostic/predictive biomarker from breast cancer to hematological cancers. Furthermore, the high potential of this molecule as therapeutical target in different carcinomas is a new challenge for precision medicine. These evidences are part of a future view to improving patient clinical management, which should allow different tumor phenotypes to be treated with tailored therapies. This article reviews the biology of NHERF1, its engagement in different signal pathways and its involvement in different cancers, with a specific focus on breast cancer. It also considers NHERF1 potential role during inflammation related to most human cancers, designating new perspectives in the study of this "Janus-like" protein.

Dissecting neutrophil complexity in cancer

Neutrophils represent the most abundant leukocyte population in human peripheral blood, and their role had long been considered restricted to their phagocytic and antimicrobial activities during the acute phase of inflammation. However, an increasing number of recent investigations had highlighted their possible impact in tumor initiation and development, and the nature of neutrophil contribution in cancer had become a hot topic in immunology. Over the years, neutrophils have been shown to display both pro-tumor and antitumor effects, emphasizing an unexpected cellular heterogeneity in cancer. In this review, we will focus on the several 'shades' of neutrophils in tumor initiation, growth and metastasis. In addition, we will discuss the clinical significance of tumor-associated neutrophils in humans and their potential targeting in cancer therapy.

CXCL1 activates TRPV1 via Gi/o protein and actin filaments

AIMS

CXCL1 is a chemokine with pleiotropic effects, including pain and itch. Itch, an unpleasant sensation that elicits the desire or reflex to scratch, it is evoked mainly from the skin and implicates activation of a specific subset of IB4+, C-type primary afferents. In previous studies we showed that acute application of CXCL1 induced a Ca²⁺ influx of low amplitude and slow kinetics in a subpopulation of transient receptor potential vanilloid type 1 (TRPV1)+/isolectin B4 (IB4)+dorsal root ganglia neurons which also responded to other itch-inducing agents. In this study we explored the mechanism behind the Ca²⁺ influx to better understand how CXCL1 acts on primary sensitive neurons to induce itch.

MATERIALS AND METHODS

Intracellular Ca²⁺ imaging and patch-clamp recordings on dorsal root ganglia neurons primary cultures and HEK293T cell transiently transfected with TRPV1 and CXCR2 plasmids were used to investigate the acute effect (12min application) of 4nM CXCL1. In primary cultures, the focus was on TRPV1+/IB4+ cells to which the itch-sensitive neurons belong.

KEY FINDINGS

The results showed that the Ca²⁺ influx induced by the acute application of CXCL1 is mediated mainly by TRPV1 receptors and depends on extracellular Ca²⁺ not on intracellular stores. TRPV1 was activated, not sensitized by CXCL1, in a CXCR2 receptors- and actin filaments-dependent manner, since specific blockers and actin depolymerizing agents disrupted the CXCL1 effect.

SIGNIFICANCE

This study brings additional data about the itch inducing mechanism of CXCL1 chemokine and about a new mechanism of TRPV1 activation via actin filaments.

The pancreatic cancer microenvironment: A true double agent

The tumor microenvironment in pancreatic cancer is a complex balance of pro- and anti-tumor components. The dense desmoplasia consists of immune cells, extracellular matrix, growth factors, cytokines, and cancer associated fibroblasts (CAF) or pancreatic stellate cells (PSC). There are a multitude of targets including hyaluronan, angiogenesis, focal adhesion kinase (FAK), connective tissue growth factor (CTGF), CD40, chemokine (C-X-C motif) receptor 4 (CXCR-4), immunotherapy, and Vitamin D. The developing clinical therapeutics will be reviewed.

Structural basis of PDZ-mediated chemokine receptor CXCR2 scaffolding by guanine nucleotide exchange factor PDZ-RhoGEF

The CXC chemokine receptor 2 (CXCR2) is a G protein coupled receptor mediating interleukin-8 chemotactic signaling and plays an important role in neutrophil mobility and tumor migration. However, efficient CXCR2 signaling requires PDZ domain-mediated scaffolding of signaling complexes at the plasma membrane and functional coupling of the signaling to specific downstream signaling pathways, in which only one PDZ protein has been characterized to interact with CXCR2. Here, we identified five novel CXCR2-binding PDZ-containing proteins, among which PDZ-RhoGEF is of particular interest because this PDZ and RGS-containing guanine nucleotide exchange factor (GEF) is also involved in cell signaling and mobility. To reveal the molecular basis of the interaction, we solved the crystal structure of PDZ-RhoGEF PDZ domain in complex with the CXCR2 C-terminal PDZ binding motif. The structure reveals that the PDZ-CXCR2 binding specificity is achieved by numerous hydrogen bonds and hydrophobic contacts with the last four CXCR2 residues contributing to specific interactions. Structural comparison of CXCR2-binding PDZ domains and PDZ-RhoGEF PDZ bound with different ligands reveals PDZ- and ligand-specific interactions that may underlie the ability of promiscuous CXCR2 binding by different PDZ domains and PDZ binding promiscuity. The structure also reveals an unexpected asymmetric disulfide bond-linked PDZ dimer that allows simultaneous parallel binding of CXCR2 to two PDZ domains. This study provides not only the structural basis for PDZ-mediated CXCR2-PDZ-RhoGEF interaction, but also a new mode of PDZ dimerization, which both could prove valuable in understanding signaling complex scaffolding in CXCR2 signaling and coupling to specific signaling pathways.

Stem and progenitor cell alterations in myelodysplastic syndromes

Recent studies have demonstrated that myelodysplastic syndromes (MDSs) arise from a small population of disease-initiating hematopoietic stem cells (HSCs) that persist and expand through conventional therapies and are major contributors to disease progression and relapse. MDS stem and progenitor cells are characterized by key founder and driver mutations and are enriched for cytogenetic alterations. Quantitative alterations in hematopoietic stem and progenitor cell (HSPC) numbers are also seen in a stage-specific manner in human MDS samples as well as in murine models of the disease. Overexpression of several markers such as interleukin-1 (IL-1) receptor accessory protein (IL1RAP), CD99, T-cell immunoglobulin mucin-3, and CD123 have begun to differentiate MDS HSPCs from healthy counterparts. Overactivation of innate immune components such as Toll-like receptors, IL-1 receptor-associated kinase/tumor necrosis factor receptor-associated factor-6, IL8/CXCR2, and IL1RAP signaling pathways has been demonstrated in MDS HSPCs and is being targeted therapeutically in preclinical and early clinical studies. Other dysregulated pathways such as signal transducer and activator of transcription 3, tyrosine kinase with immunoglobulinlike and EGF-like domains 1/angiopoietin-1, p21-activated kinase, microRNA 21, and transforming growth factor β are also being explored as therapeutic targets against MDS HSPCs. Taken together, these studies have demonstrated that MDS stem cells are functionally critical for the initiation, transformation, and relapse of disease and need to be targeted therapeutically for future curative strategies in MDSs.

Role of the PDZ-scaffold protein NHERF1/EBP50 in cancer biology: from signaling regulation to clinical relevance

The transmission of cellular information requires fine and subtle regulation of proteins that need to interact in a coordinated and specific way to form efficient signaling networks. The spatial and temporal coordination relies on scaffold proteins. Thanks to protein interaction domains such as PDZ domains, scaffold proteins organize multiprotein complexes enabling the proper transmission of cellular information through intracellular networks. NHERF1/EBP50 is a PDZ-scaffold protein that was initially identified as an organizer and regulator of transporters and channels at the apical side of epithelia through actin-binding ezrin-moesin-radixin proteins. Since, NHERF1/EBP50 has emerged as a major regulator of cancer signaling network by assembling cancer-related proteins. The PDZ-scaffold EBP50 carries either anti-tumor or pro-tumor functions, two antinomic functions dictated by EBP50 expression or subcellular localization. The dual function of NHERF1/EBP50 encompasses the regulation of several major signaling pathways engaged in cancer, including the receptor tyrosine kinases PDGFR and EGFR, PI3K/PTEN/AKT and Wnt-β-catenin pathways.

CXCR2 signaling regulates KRAS(G¹²D)-induced autocrine growth of pancreatic cancer

Pharmacological inhibition of RAS, the master regulator of pancreatic ductal adenocarcinoma (PDAC), continues to be a challenge. Mutations in various isoforms of RAS gene, including KRAS are known to upregulate CXC chemokines; however, their precise role in KRAS-driven pancreatic cancer remains unclear. In this report, we reveal a previously unidentified tumor cell-autonomous role of KRAS^(G12D)-induced CXCR2 signaling in mediating growth of neoplastic PDAC cells. Progressively increasing expression of mCXCR2 and its ligands was detected in the malignant ductal cells of Pdx1-cre;LSL-Kras^(G12D) mice. Knocking-down CXCR2 in KRAS^(G12D)-bearing human pancreatic duct-derived cells demonstrated a significant decrease in the in vitro and in vivo tumor cell proliferation. Furthermore, CXCR2 antagonists showed selective growth inhibition of KRAS^(G12D)-bearing cells in vitro. Intriguingly, both genetic and pharmacological inhibition of CXCR2 signaling in KRAS^(G12D)-bearing pancreatic ductal cells reduced the levels of KRAS protein, strongly implying the presence of a KRAS-CXCR2 feed-forward loop. Together, these data demonstrate the role of CXCR2 signaling in KRAS^(G12D)-induced growth transformation and progression in PDAC.

A new PDAC mouse model originated from iPSCs-converted pancreatic cancer stem cells (CSCcm)

Pancreatic ductal adenocarcinoma (PDAC) is the most representative form of pancreatic cancers. PDAC solid tumours are constituted of heterogeneous populations of cells including cancer stem cells (CSCs), differentiated cancer cells, desmoplastic stroma and immune cells. The identification and consequent isolation of pancreatic CSCs facilitated the generation of genetically engineered murine models. Nonetheless, the current models may not be representative for the spontaneous tumour occurrence. In the present study, we show the generation of a novel pancreatic iPSC-converted cancer stem cell lines (CSCcm) as a cutting-edge model for the study of PDAC. The CSCcm lines were achieved only by the influence of pancreatic cancer cell lines conditioned medium and were not subjected to any genetic manipulation. The xenografts tumours from CSCcm lines displayed histopathological features of ADM, PanIN and PDAC lesions. Further molecular characterization from RNA-sequencing analysis highlighted primary culture cell lines (1^st CSCcm) as potential candidates to represent the pancreatic CSCs and indicated the establishment of the pancreatic cancer molecular pattern in their subsequent progenies 2^nd CSCcm and 3^rd CSCcm. In addition, preliminary RNA-seq SNPs analysis showed that the distinct CSCcm lines did not harbour single point mutations for the oncogene Kras codon 12 or 13. Therefore, PDAC-CSCcm model may provide new insights about the actual occurrence of the pancreatic cancer leading to develop different approaches to target CSCs and abrogate the progression of this fatidic disease.

Adeno-associated virus (AAV) vectors in cancer gene therapy

Gene delivery vectors based on adeno-associated virus (AAV) have been utilized in a large number of gene therapy clinical trials, which have demonstrated their strong safety profile and increasingly their therapeutic efficacy for treating monogenic diseases. For cancer applications, AAV vectors have been harnessed for delivery of an extensive repertoire of transgenes to preclinical models and, more recently, clinical trials involving certain cancers. This review describes the applications of AAV vectors to cancer models and presents developments in vector engineering and payload design aimed at tailoring AAV vectors for transduction and treatment of cancer cells. We also discuss the current status of AAV clinical development in oncology and future directions for AAV in this field.

CXCR2 Inhibition Profoundly Suppresses Metastases and Augments Immunotherapy in Pancreatic Ductal Adenocarcinoma

CXCR2 has been suggested to have both tumor-promoting and tumor-suppressive properties. Here we show that CXCR2 signaling is upregulated in human pancreatic cancer, predominantly in neutrophil/myeloid-derived suppressor cells, but rarely in tumor cells. Genetic ablation or inhibition of CXCR2 abrogated metastasis, but only inhibition slowed tumorigenesis. Depletion of neutrophils/myeloid-derived suppressor cells also suppressed metastasis suggesting a key role for CXCR2 in establishing and maintaining the metastatic niche. Importantly, loss or inhibition of CXCR2 improved T cell entry, and combined inhibition of CXCR2 and PD1 in mice with established disease significantly extended survival. We show that CXCR2 signaling in the myeloid compartment can promote pancreatic tumorigenesis and is required for pancreatic cancer metastasis, making it an excellent therapeutic target.

Mining for Candidate Genes Related to Pancreatic Cancer Using Protein-Protein Interactions and a Shortest Path Approach

Pancreatic cancer (PC) is a highly malignant tumor derived from pancreas tissue and is one of the leading causes of death from cancer. Its molecular mechanism has been partially revealed by validating its oncogenes and tumor suppressor genes; however, the available data remain insufficient for medical workers to design effective treatments. Large-scale identification of PC-related genes can promote studies on PC. In this study, we propose a computational method for mining new candidate PC-related genes. A large network was constructed using protein-protein interaction information, and a shortest path approach was applied to mine new candidate genes based on validated PC-related genes. In addition, a permutation test was adopted to further select key candidate genes. Finally, for all discovered candidate genes, the likelihood that the genes are novel PC-related genes is discussed based on their currently known functions.

Boronic acid-containing aminopyridine- and aminopyrimidinecarboxamide CXCR1/2 antagonists: Optimization of aqueous solubility and oral bioavailability

The chemokine receptors CXCR1 and CXCR2 are important pharmaceutical targets due to their key roles in inflammatory diseases and cancer progression. We have previously identified 2-[5-(4-fluoro-phenylcarbamoyl)-pyridin-2-ylsulfanylmethyl]-phenylboronic acid (SX-517) and 6-(2-boronic acid-5-trifluoromethoxy-benzylsulfanyl)-N-(4-fluoro-phenyl)-nicotinamide (SX-576) as potent non-competitive boronic acid-containing CXCR1/2 antagonists. Herein we report the synthesis and evaluation of aminopyridine and aminopyrimidine analogs of SX-517 and SX-576, identifying (2-{(benzyl)[(5-boronic acid-2-pyridyl)methyl]amino}-5-pyrimidinyl)(4-fluorophenylamino)formaldehyde as a potent chemokine antagonist with improved aqueous solubility and oral bioavailability.

IL8-CXCR2 pathway inhibition as a therapeutic strategy against MDS and AML stem cells

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Novel therapeutic targets against preleukemic stem cells need to be identified for potentially curative strategies. We conducted parallel transcriptional analysis of highly fractionated stem and progenitor populations in MDS, AML, and control samples and found interleukin 8 (IL8) to be consistently overexpressed in patient samples. The receptor for IL8, CXCR2, was also significantly increased in MDS CD34(+) cells from a large clinical cohort and was predictive of increased transfusion dependence. High CXCR2 expression was also an adverse prognostic factor in The Cancer Genome Atlas AML cohort, further pointing to the critical role of the IL8-CXCR2 axis in AML/MDS. Functionally, CXCR2 inhibition by knockdown and pharmacologic approaches led to a significant reduction in proliferation in several leukemic cell lines and primary MDS/AML samples via induction of G0/G1 cell cycle arrest. Importantly, inhibition of CXCR2 selectively inhibited immature hematopoietic stem cells from MDS/AML samples without an effect on healthy controls. CXCR2 knockdown also impaired leukemic growth in vivo. Together, these studies demonstrate that the IL8 receptor CXCR2 is an adverse prognostic factor in MDS/AML and is a potential therapeutic target against immature leukemic stem cell-enriched cell fractions in MDS and AML.

Effect of Tai Chi on mononuclear cell functions in patients with non-small cell lung cancer

BACKGROUND

Tai Chi is the Chinese traditional medicine exercise for mind-body health. The objective of this study is to investigate the effect of Tai Chi Chuan (TCC) exercise on the proliferative and cytolytic/tumoricidal activities of peripheral blood mononuclear cells (PBMCs) in postsurgical non-small cell lung cancer (NSCLC) patients.

METHODS

Patients (n = 27) were randomly divided into the control group (n = 13) and the TCC group (n = 14). TCC group participated in Tai Chi 24-type exercise for 16 weeks, 60-min every time, and three times a week. Peripheral blood was collected and PBMCs isolated before and after the 16-week TCC, PBMC proliferation and co-culture of PBMCs with the NSCLC cell line A549 were performed for proliferation and cell cytolysis assays. Analysis of NKT cells, NK cells, and CD123+ and CD11c + dendritic cells were also performed.

RESULTS

(1) After 16-week of TCC, cell proliferation increased significantly as compared with the control. (2) PBMCs from the TCC group also demonstrated enhanced cytolytic/oncolytic activity against A549 cells. (3) Significant differences were also found in NK cell percentage at t = 16 weeks, post-pre changes of NKT and DC11c between groups.

CONCLUSION

Regular Tai Chi exercise has the promise of enhancing PBMC proliferative and cytolytic activities in NSCLC patients. Our results affirm the value of a future trial with a larger scale and longer duration for cancer survivors.

TRIAL REGISTRATION

ChiCTR-TRC-11001404 .

The actin-bundling protein TRIOBP-4 and -5 promotes the motility of pancreatic cancer cells

TRIOBP isoforms 4 and 5 (TRIOBP-4/-5) are an actin-bundling protein associated with hearing loss. Here, we showed that TRIOBP-4/-5 was up-regulated in human pancreatic carcinoma cells. Knockdown of TRIOBP-4/-5 led to a loss of filopodia and a decrease in cell motility. Confocal microscopy showed that re-expression of GFP-TRIOBP-4 or -5 restored the filopodial formation in TRIOBP-4/-5-deficient PANC-1 cells. Finally, TRIOBP-4/-5 was shown to be overexpressed in human pancreatic cancer tissues. These results demonstrate a novel role of TRIOBP-4/-5 that promotes the motility of pancreatic cancer cells via regulating actin cytoskeleton reorganization in the filopodia of the cells.

Crystal structure of the NHERF1 PDZ2 domain in complex with the chemokine receptor CXCR2 reveals probable modes of PDZ2 dimerization

The formation of CXCR2-NHERF1-PLCβ2 macromolecular complex in neutrophils regulates CXCR2 signaling and plays a key role in neutrophil chemotaxis and transepithelial neutrophilic migration. However, NHERF1 by itself, with only two PDZ domains, has a limited capacity in scaffolding the multiprotein-complex formation. Here we report the crystal structure of the NHERF1 PDZ2 domain in complex with the C-terminal CXCR2 sequence. The structure reveals that the PDZ2-CXCR2 binding specificity is achieved by numerous hydrogen bonds and hydrophobic contacts with the last four CXCR2 residues contributing to specific interactions. The structure also reveals two probable modes of PDZ2 dimerization where the two canonical ligand-binding pockets are well separated and orientated in a unique parallel fashion. This study provides not only the structural basis for the PDZ-mediated NHERF1-CXCR2 interaction, but also an additional example of how PDZ domains may dimerize, which both could prove valuable in understanding NHERF1 complex-scaffolding function in neutrophils.

Blockage of CXCR2 suppresses tumor growth of intrahepatic cholangiocellular carcinoma

BACKGROUND/AIMS

Complete operative resection is the only approach to cure for intrahepatic cholangiocellular carcinoma (ICC), but the disease's prognosis is notably poor. A novel therapeutic approach is urgently required. CXC chemokine receptor 2 (CXCR2) has been associated with tumorigenesis and metastasis in human cancers. In this study, we investigated the suppressive effect of ICC growth by blocking CXCR2.

MATERIAL AND METHODS

The role of CXCR2 was estimated using the human ICC cell lines, RBE and SSP25. CXCR2 small interfering RNA (siRNA) and an antagonist (SB225002) were used to block CXCR2. Proliferation assays, migration assays, and invasion assays were performed to confirm the suppressive effect of blocking CXCR2. Subcutaneous SSP25 tumors were established in athymic nude mice, and the mice were given SB225002. The expression of CXCR2 in ICC was determined by immunohistochemical staining of 34 ICC specimens. We investigated the relationship between CXCR2 expression and prognosis in ICC.

RESULTS

The prognosis of patients who had higher CXCR2 expression in ICC was significantly poor (P = .004). CXCR2 siRNA treatment significantly suppressed CXCR2 expression in both RBE and SSP25. Cell proliferation, migration, and invasion were significantly suppressed by both CXCR2 siRNA and SB225002 compared with the control group. SB225002 also suppressed the growth of transplanted subcutaneous tumors (P = .02) CONCLUSION: Our results demonstrated that blocking CXCR2 clearly suppressed the development of ICC. Blocking CXCR2 may be a promising therapeutic approach for ICC.

New conformational state of NHERF1-CXCR2 signaling complex captured by crystal lattice trapping

NHERF1 is a PDZ adaptor protein that scaffolds the assembly of diverse signaling complexes and has been implicated in many cancers. However, little is known about the mechanism responsible for its scaffolding promiscuity or its ability to bind to multiple targets. Computational studies have indicated that PDZ promiscuity may be attributed to its conformational dynamics, but experimental evidence for this relationship remains very limited. Here we examine the conformational flexibility of the NHERF1 PDZ1 domain using crystal lattice trapping via solving PDZ1 structure of a new crystal form. The structure, together with prior PDZ1 structures of a different space group, reveals that 4 of 11 ligand-interacting residues undergo significant crystal packing-induced structural changes. Most of these residues correspond to the residues involved in allosteric transition when a peptide ligand binds. In addition, a subtle difference in ligand conformations causes the same peptide to bind in slightly different modes in different crystal forms. These findings indicate that substantial structural flexibility is present in the PDZ1 peptide-binding pocket, and the structural substate trapped in the present crystal form can be utilized to represent the conformational space accessible to the protein. Such knowledge will be critical for drug design against the NHERF1 PDZ1 domain, highlighting the continued need for experimentally determined PDZ1-ligand complexes.