Matrix Metalloproteinase-9/Neutrophil Gelatinase-Associated Lipocalin Complex Activity in Human Glioma Samples Predicts Tumor Presence and Clinical Prognosis

Identification of SLC22A17 DNA methylation hotspot as a potential biomarker in cutaneous melanoma

BACKGROUND

Cancer onset and progression are driven by genetic and epigenetic alterations leading to oncogene activation and the silencing of tumor suppressor genes. Among epigenetic mechanisms, DNA methylation (methDNA) is gaining growing interest in cancer. Promoter hypomethylation is associated with oncogene activation while intragenic methDNA can be involved in transcriptional elongation, alternative spicing, and the activation of cryptic start sites. Several genes involved in the modulation of the tumor microenvironment are regulated by methDNA, including the Solute Carrier Family 22 Member 17 (SLC22A17), which is involved in iron trafficking and extracellular matrix remodeling cooperating with the Gelatinase-Associated Lipocalin (NGAL) ligand. However, the exact role of intragenic methDNA in cancer has not been fully investigated. Therefore, the aim of the present study is to explore the role of methDNA in the regulation of SLC22A17 in cutaneous melanoma (CM), used as a tumor model.

METHODS

Correlation and differential analyses between SLC22A17 expression and methDNA were performed using the data contained in The Cancer Genome Atlas and Gene Expression Omnibus databases. Functional studies on melanoma cell lines treated with 5-Azacytidine (5-Aza) were conducted to assess the correlation between methDNA and SLC22A17 expression. A validation study on the diagnostic potential of the in silico-identified SLC22A17 methDNA hotspot was finally performed by analyzing tissue samples obtained from CM patients and healthy controls.

RESULTS

The computational analyses revealed that SLC22A17 was significantly downregulated in CM, and its expression was related to promoter hypomethylation and intragenic hypermethylation. Moreover, SLC22A17 overexpression and hypermethylation of two intragenic methDNA hotspots were associated with a better clinical outcome in CM patients. The correlation between SLC22A17 methDNA and expression was confirmed in 5-Aza-treated cells. In agreement with in silico analyses, the SLC22A17 promoter methylation hotspot showed higher methDNA levels in CM samples compared to nevi. In addition, the methDNA levels of this hotspot were positively correlated with advanced CM.

CONCLUSIONS

The SLC22A17 methDNA hotspot could represent a promising biomarker for CM, highlighting the regulatory role of methDNA on SLC22A17 expression. These results pave the way for the identification of novel epigenetic biomarkers and therapeutic targets for the management of CM patients.

The acute inflammatory response to copper(II)-doped biphasic calcium phosphates

Infection and inflammation are two key features to consider to avoid septic or aseptic loosening of bone-implanted biomaterials. In this context, various approaches to fine-tune the biomaterial's properties have been studied in order to modulate the crosstalk between immune and skeletal cells. Cation-doping strategies for tuning of calcium phosphates properties has been evidenced as a promising way to control the biomaterial-induced inflammatory process, and thus improving their osteoimmunomodulatory properties. Copper(II) ions are recognized for their antibacterial potential, but the literature on their impact on particulate material-induced acute inflammation is scarce. We synthesized copper(II) ions-doped biphasic calcium phosphate (BCP), intended to exhibit osteoimmunomodulatory properties. We addressed in vitro, for the first time, the inflammatory response of human primary polymorphonuclear neutrophils (PMNs) to copper(II) ions-doped or undoped (BCP) powders, synthesized by an original and robust wet method, in the presence or absence of LPS as a costimulant to mimic an infectious environment. ELISA and zymography allowed us to evidence, in vitro, a specific increase in IL-8 and GRO-α secretion but not MIP-1β, TNF-α, or MMP-9, by PMNs. To assess in vivo relevance of these findings, we used a mouse air pouch model. Thanks to flow cytometry analysis, we highlighted an increased PMN recruitment with the copper(II) ions-doped samples compared to undoped samples. The immunomodulatory effect of copper(II) ions-doped BCP powders and the consequent induced moderate level of inflammation may promote bacterial clearance by PMNs in addition to the antimicrobial potential of the material. Copper(II) doping provides new insights into calcium phosphate (CaP)-based biomaterials for prosthesis coating or bone reconstruction by effectively modulating the inflammatory environment.

Diagnosis Biomarkers of Cholangiocarcinoma in Human Bile: An Evidence-Based Study

Simple Summary

A liquid biopsy has the characteristics of low trauma and easy acquisition in the diagnosis of cholangiocarcinoma. Many researchers try to find diagnostic or prognostic biomarkers of CCA through blood, urine, bile and other body fluids. Due to the close proximity of bile to the lesion and the stable nature, bile gradually comes into people’s view. The evaluation of human bile diagnostic biomarkers is not only to the benefit of screening more suitable clinical markers but also of exploring the pathological changes of the disease.

Abstract

Cholangiocarcinoma (CCA) is a multifactorial malignant tumor of the biliary tract, and the incidence of CCA is increasing in recent years. At present, the diagnosis of CCA mainly depends on imaging and invasive examination, with limited specificity and sensitivity and late detection. The early diagnosis of CCA always faces the dilemma of lacking specific diagnostic biomarkers. Non-invasive methods to assess the degree of CAA have been developed throughout the last decades. Among the many specimens looking for CCA biomarkers, bile has gotten a lot of attention lately. This paper mainly summarizes the recent developments in the current research on the diagnostic biomarkers for CCA in human bile at the levels of the gene, protein, metabolite, extracellular vesicles and volatile organic compounds.

Plasmatic MMP9 released from tumor-infiltrating neutrophils is predictive for bevacizumab efficacy in glioblastoma patients: an AVAglio ancillary study

We previously identified matrix metalloproteinase 2 (MMP2) and MMP9 plasma levels as candidate biomarkers of bevacizumab activity in patients with recurrent glioblastoma. The aim of this study was to assess the predictive value of MMP2 and MMP9 in a randomized phase III trial in patients with newly diagnosed glioblastoma and to explore their tumor source. In this post hoc analysis of the AVAglio trial (AVAGlio/NCT00943826), plasma samples from 577 patients (bevacizumab, n = 283; placebo, n = 294) were analyzed for plasma MMP9 and MMP2 levels by enzyme-linked immunosorbent assay. A prospective local cohort of 38 patients with newly diagnosed glioblastoma was developed for analysis of tumor characteristics by magnetic resonance imaging and measurement of plasma and tumor levels of MMP9 and MMP2. In this AVAglio study, MMP9, but not MMP2, was correlated with bevacizumab efficacy. Patients with low MMP9 derived a significant 5.2-month overall survival (OS) benefit with bevacizumab (HR 0.51, 95% CI 0.34-0.76, p = 0.0009; median 13.6 vs. 18.8 months). In multivariate analysis, a significant interaction was seen between treatment and MMP9 (p = 0.03) for OS. In the local cohort, we showed that preoperative MMP9 plasma levels decreased after tumor resection and were correlated with tumor levels of MMP9 mRNA (p = 0.03). However, plasma MMP9 was not correlated with tumor size, invasive pattern, or angiogenesis. Using immunohistochemistry, we showed that MMP9 was expressed by inflammatory cells but not by tumor cells. After cell sorting, we showed that MMP9 was expressed by CD45+ immune cells. Finally, using flow cytometry, we showed that MMP9 was expressed by tumor-infiltrating neutrophils. In conclusion, circulating MMP9 is predictive of bevacizumab efficacy and is released by tumor-infiltrating neutrophils.

NGAL as a Potential Target in Tumor Microenvironment

The signaling network between cancer and stromal cells plays a crucial role in tumor microenvironment. The fate of tumor progression mainly depends on the huge amount of information that these cell populations exchange from the onset of neoplastic transformation. Interfering with such signaling has been producing exciting results in cancer therapy: just think of anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies that, acting as immune checkpoint inhibitors, interrupt the inhibitory signaling exerted by cancer cells on immune cells or the CAR-T technology that fosters the reactivation of anti-tumoral immunity in a restricted group of leukemias and lymphomas. Nevertheless, many types of cancers, in particular solid tumors, are still refractory to these treatments, so the identification of novel molecular targets in tumor secretome would benefit from implementation of current anti-cancer therapeutical strategies. Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a secreted protein abundantly expressed in the secretome of various human tumors. It represents a promising target for the multiple roles that are played inside cancer and stromal cells, and also overall in their cross-talk. The review focuses on the different roles of NGAL in tumor microenvironment and in cancer senescence-associated secretory phenotype (SASP), highlighting the most crucial functions that could be eventually targetable in cancer therapy.

NGAL as a Potential Target in Tumor Microenvironment

The signaling network between cancer and stromal cells plays a crucial role in tumor microenvironment. The fate of tumor progression mainly depends on the huge amount of information that these cell populations exchange from the onset of neoplastic transformation. Interfering with such signaling has been producing exciting results in cancer therapy: just think of anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies that, acting as immune checkpoint inhibitors, interrupt the inhibitory signaling exerted by cancer cells on immune cells or the CAR-T technology that fosters the reactivation of anti-tumoral immunity in a restricted group of leukemias and lymphomas. Nevertheless, many types of cancers, in particular solid tumors, are still refractory to these treatments, so the identification of novel molecular targets in tumor secretome would benefit from implementation of current anti-cancer therapeutical strategies. Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a secreted protein abundantly expressed in the secretome of various human tumors. It represents a promising target for the multiple roles that are played inside cancer and stromal cells, and also overall in their cross-talk. The review focuses on the different roles of NGAL in tumor microenvironment and in cancer senescence-associated secretory phenotype (SASP), highlighting the most crucial functions that could be eventually targetable in cancer therapy.

NGAL as a Potential Target in Tumor Microenvironment

The signaling network between cancer and stromal cells plays a crucial role in tumor microenvironment. The fate of tumor progression mainly depends on the huge amount of information that these cell populations exchange from the onset of neoplastic transformation. Interfering with such signaling has been producing exciting results in cancer therapy: just think of anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies that, acting as immune checkpoint inhibitors, interrupt the inhibitory signaling exerted by cancer cells on immune cells or the CAR-T technology that fosters the reactivation of anti-tumoral immunity in a restricted group of leukemias and lymphomas. Nevertheless, many types of cancers, in particular solid tumors, are still refractory to these treatments, so the identification of novel molecular targets in tumor secretome would benefit from implementation of current anti-cancer therapeutical strategies. Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a secreted protein abundantly expressed in the secretome of various human tumors. It represents a promising target for the multiple roles that are played inside cancer and stromal cells, and also overall in their cross-talk. The review focuses on the different roles of NGAL in tumor microenvironment and in cancer senescence-associated secretory phenotype (SASP), highlighting the most crucial functions that could be eventually targetable in cancer therapy.

Expression and prognostic value of CXCL12/CXCR4/CXCR7 axis in clear cell renal cell carcinoma

BACKGROUND

CXCL12 or stromal-derived factor-1 is a chemokine that binds to two receptors CXCR4 and CXCR7 and takes part in both physiological and pathological cell functions. The disruption of the CXCL12/CXCR4/CXCR7 chemokine axis is seen in various types of cancers.

METHODS

We have immunohistochemically analyzed the expression of CXCL12 and its receptors in clear cell renal cell carcinoma patients. The study included 85 tissue samples. Since samples exhibited heterogeneity of expression intensity and staining localization (cytoplasmatic and membranous), histoscores were calculated, and their associations with clinicopathological parameters were analyzed.

RESULTS

Both cytoplasmatic CXCR7 and CXCL12 histoscores were associated with greater tumour size, while CXCL12 staining was associated with a higher grade as well. Mortality was associated with tumour size and both membranous and cytoplasmatic CXCL12 histoscores. With each centimetre in tumour size, survival decreases 1.3 times, while CXCL12C histoscore higher than 73 was associated with 2.3 greater risk of mortality. CXCR4 histoscore could only be predicted by female gender and neither cytoplasmatic nor membranous CXCR4 expression was found to be a mortality predictor.

CONCLUSION

Our data suggest that regarding overall survival, CXCL12 could be considered a valuable prognostic marker.

Expression Profile Analysis Identifies a Novel Seven Immune-Related Gene Signature to Improve Prognosis Prediction of Glioblastoma

Glioblastoma multiform (GBM) is a malignant central nervous system cancer with dismal prognosis despite conventional therapies. Scientists have great interest in using immunotherapy for treating GBM because it has shown remarkable potential in many solid tumors, including melanoma, non-small cell lung cancer, and renal cell carcinoma. The gene expression patterns, clinical data of GBM individuals from the Cancer Genome Atlas database (TCGA), and immune-related genes (IRGs) from ImmPort were used to identify differentially expressed IRGs through the Wilcoxon rank-sum test. The association between each IRG and overall survival (OS) of patients was investigated by the univariate Cox regression analysis. LASSO Cox regression assessment was conducted to explore the prognostic potential of the IRGs of GBM and construct a risk score formula. A Kaplan–Meier curve was created to estimate the prognostic role of IRGs. The efficiency of the model was examined according to the area under the receiver operating characteristic (ROC) curve. The TCGA internal dataset and two GEO external datasets were used for model verification. We evaluated IRG expression in GBM and generated a risk model to estimate the prognosis of GBM individuals with seven optimal prognostic expressed IRGs. A landscape of 22 types of tumor-infiltrating immune cells (TIICs) in glioblastoma was identified, and we investigated the link between the seven IRGs and the immune checkpoints. Furthermore, there was a correlation between the IRGs and the infiltration level in GBM. Our data suggested that the seven IRGs identified in this study are not only significant prognostic predictors in GBM patients but can also be utilized to investigate the developmental mechanisms of GBM and in the design of personalized treatments for them.

Urine Neutrophil Gelatinase-Associated Lipocalin a Possible Diagnostic Marker for Egyptian Hepatocellular Carcinoma Patients

BACKGROUND

Most effective method for reducing mortality from hepatocellular carcinoma (HCC) is early diagnosis. Despite its lack of adequate sensitivity, ultrasound is considered fundamental for HCC screening.

AIM

to evaluate urinary neutrophil gelatinase-associated lipocalin (NGAL) as non-invasive marker for HCC diagnosis in Egyptian patients.

METHODS

One hundred and twenty patients were divided into three groups (40 patients each): patients with chronic viral hepatitis (HCV or HBV), cirrhotic patients and HCC patients and 40 healthy age and gender matched subjects were enrolled as control group. After clinical assessments, urinary NGAL was measured by enzyme-linked immunosorbent assay.

RESULTS

Our results revealed that median level of urinary NGAL was 290, 834, 1090 and 1925 pg/ml in control, chronic hepatitis, cirrhotic and HCC groups respectively among studied groups (p<0.001). Receiver operating characteristics (ROC) analysis showed that urinary NGAL cutoff value of 1255 ng/ml could discriminate between HCC and cirrhosis. The area under curve (AUC) was 0.95 with 90% sensitivity, 87.5% specificity (p-value <0.001). In HCC group, urine NGAL level didn`t show significant correlation with Child Pugh score, MELD score or Barcelona Clinic Liver Cancer (BCLC) stage.

CONCLUSION

Urinary NGAL could be a simple, non-invasive test for diagnosis of HCC in chronic liver disease patients.<br />.

Lcn2-derived Circular RNA (hsa_circ_0088732) Inhibits Cell Apoptosis and Promotes EMT in Glioma via the miR-661/RAB3D Axis

Background: Glioma is the most common malignant tumor of the central nervous system, and often displays invasive growth. Recently, circular RNA (circRNA), which is a novel non-coding type of RNA, has been shown to play a vital role in glioma tumorigenesis. However, the functions and mechanism of lipocalin-2 (Lcn2)-derived circular RNA (hsa_circ_0088732) in glioma progression remain unclear.

Methods: We evaluated hsa_circ_0088732 expression by fluorescence in situ hybridization (FISH), Sanger sequencing, and PCR assays. Cell apoptosis was evaluated by flow cytometry and Hoechst 33258 staining. Transwell migration and invasion assays were performed to measure cell metastasis and viability. In addition, the target miRNA of hsa_circ_0088732 and the target gene of miR-661 were predicted by a bioinformatics analysis, and the interactions were verified by dual-luciferase reporter assays. RAB3D expression was analyzed by an immunochemistry assay, and E-cadherin, N-cadherin, and vimentin protein expression were examined by western blot assays. A mouse xenograft model was developed and used to analyze the effects of hsa_circ_0088732 on glioma growth in vivo.

Results: We verified that hsa_circ_0088732 is circular and highly expressed in glioma tissues. Knockdown of hsa_circ_0088732 induced glioma cell apoptosis and inhibited glioma cell migration, invasion, and epithelial-mesenchymal transition (EMT). We found that hsa_circ_0088732 negatively regulated miR-661 by targeting miR-661, and RAB3D was a target gene of miR-661. In addition, inhibition of miR-661 promoted glioma cell metastasis and suppressed cell apoptosis. Knockdown of RAB3D induced cell apoptosis and suppressed cell metastasis. Moreover, hsa_circ_0088732 accelerated glioma progression through its effects on the miR-661/RAB3D axis. Finally, results from a mouse xenograft model confirmed that knockdown of hsa_circ_0088732 induced miR-661 expression, resulting in suppression of RAB3D expression and inhibition of tumor growth in vivo.

Conclusion: We demonstrated that hsa_circ_0088732 facilitated glioma progression by sponging miR-661 to increase RAB3D expression. This study provides a theoretical basis for understanding the development and occurrence of glioma, as well as for the development of targeted drugs.

Chronic Hypoxia-Induced Microvessel Proliferation and Basal Membrane Degradation in the Bone Marrow of Rats Regulated through the IL-6/JAK2/STAT3/MMP-9 Pathway

Chronic hypoxia (CH) is characterized by long-term hypoxia that is associated with microvessel proliferation and basal membrane (BM) degradation in tissues. The IL-6/JAK2/STAT3/MMP-9 pathway has been described in a variety of human cancers and plays an essential role in microvessel proliferation and BM degradation. Therefore, this study investigated the role of the IL-6/JAK2/STAT3/MMP-9 pathway in hypoxia-mediated microvessel proliferation and BM degradation in the rat bone marrow. Eighty pathogen-free Sprague Dawley male rats were randomly divided into four groups (20 per group)—control group, CH group (exposed to hypoxia in a hypobaric chamber at a simulated altitude of 5000 m for 28 d), CH + STAT3 inhibitor group (7.5 mg/kg/d), and CH + DMSO group. Microvessel density (MVD) and BM degradation in the bone marrow were determined by immunofluorescence staining and transmission electron microscopy. Serum IL-6 levels were assessed by enzyme-linked immunosorbent assay (ELISA), and the levels of P-JAK2, P-STAT3, and MMP-9 were assessed by western blot analysis and real-time reverse transcription PCR (RT-PCR). Hypoxia increased serum IL-6 levels, which in turn increased JAK2 and STAT3 phosphorylation, which subsequently upregulated MMP-9. Overexpression of MMP-9 significantly promoted the elevation of MVD and BM degradation. Inhibition of STAT3 using an inhibitor, SH-4-54, significantly downregulated MMP-9 expression and decreased MVD and BM degradation. Surprisingly, STAT3 inhibition also decreased serum IL-6 levels and JAK2 phosphorylation. Our results suggest that the IL-6/JAK2/STAT3/MMP-9 pathway might be related to CH-induced microvessel proliferation and BM degradation in the bone marrow.

Implication and role of neutrophil gelatinase-associated lipocalin in cancer: lipocalin-2 as a potential novel emerging comprehensive therapeutic target for a variety of cancer types

Cancer is a leading cause of mortalities worldwide. Over the past few decades, exploration of molecular mechanisms behind cancer initiation and progression has been of great interest in the viewpoint of both basic and clinical scientists. It is generally believed that identification of key molecules implicated in cancer pathology not only improves our understanding of the disease, but also could result in introduction of novel therapeutic strategies. Neutrophil gelatinase-associated lipocalin (NGAL)/lipocalin-2 (LCN2) is a member of lipocalin superfamily with a variety of functions. Although the main function of LCN2 is still unknown, many studies confirmed its significant role in the initiation, progression, and metastasis of various types of cancer. Furthermore, aberrant expression of LCN2 is also concerned with the chemo- and radio-resistant phenotypes of tumors. Here, we will review the contribution of known functions of LCN2 to the pathophysiology of cancer. We also highlight how the deregulated expression of LCN2 is associated with a variety of fatal types of cancer for which there are no effective therapeutic modalities. The unique and multiple functions of LCN2 and its widespread expression in different types of cancer prompted us to suggest LCN2 could be considered either as a valuable diagnostic and prognostic biomarker or as a potential novel therapeutic target.

LCN2-interacting proteins and their expression patterns in brain tumors

Lipocalin 2 (LCN2) is a member of the lipocalin family. Elevated expression of LCN2 has been observed in many human tumors, suggesting it might be a potential biomarker and/or therapeutic target in malignancies. In this study, we aimed to explore LCN2 interacting proteins through bioinformatics, as well as their biological functions. Protein-protein interaction networks (PPIN) were constructed using LCN2 and its interacting proteins as the core node. These PPINs were scale free biological networks in which LCN2 and its interacting proteins could connect or cross-talk with at least one partner protein. Both functional and KEGG pathway enrichment analyses identified the known and potential biological functions of the PPIN, such as cell migration and cancer-related pathways. Expression levels of the PPIN proteins, as well as their expression correlations, in five types of brain tumor, were analyzed and integrated into the PPIN to illustrate a dynamic change. A significant correlation was found between the survival time of glioblastoma patients and the expression level of 10 genes (LCN2, MMP9, MMP2, PDE4DIP, L2HGDH, HNRNPA1, DDX31, LOXL2, FAM60A and RNF25). Taken together, our results suggest that LCN2 and its interacting proteins are mostly differentially expressed and have a distinguishing co-expression pattern. They might promote proliferation and migration via cell migration signaling and cancer-related pathways. LCN2 and its interacting proteins might be potential biomarkers in glioblastoma.

TCF7L2 and EGR1 synergistic activation of transcription of LCN2 via an ERK1/2-dependent pathway in esophageal squamous cell carcinoma cells

High level expression of lipocalin 2 (LCN2) usually indicates poor prognosis in esophageal squamous cell carcinoma (ESCC) and many other cancers. Our previous study showed LCN2 promotes migration and invasion of ESCC cells through a novel positive feedback loop. However, the key transcription activation protein (KTAP) in the loop had not yet been identified. In this study, we first predicted the most probable KTAPs by bioinformatic analysis. We then assessed the transcription regulatory regions in the human LCN2 gene by fusing deletions of its 5'-flanking region to a dual-luciferase reporter. We found that the region -720/-200 containing transcription factor 7-like 2 (TCF7L2) (-273/-209) and early growth response 1 (EGR1) (-710/-616) binding sites is crucial for LCN2 promoter activity. Chromatin immunoprecipitation (ChIP) experiments demonstrated that TCF7L2 and EGR1 bound directly to their binding sites within the LCN2 promoter as KTAPs. Mechanistically, overexpression of TCF7L2 and EGR1 increased endogenous LCN2 expression via the ERK signaling pathway. Treatment with recombinant human LCN2 protein enhanced activation of the ERK pathway to facilitate endogenous LCN2 expression, as well as increase the expression level of TCF7L2 and EGR1. Treatment with the MEK inhibitor U0126 inhibited the activation by TCF7L2 or EGR1 overexpression. Moreover, overexpression of TCF7L2 or EGR1 accelerated the migration and invasion of ESCC cells. A synergistic effect was observed between TCF7L2 and EGR1 in amplifying the induction of LCN2 and enhancing migration and invasion. Taken together, our study indicates that TCF7L2 and EGR1 are the KTAPs of LCN2, within a positive "LCN2 → MEK/ERK → LCN2" path, to promote the migration and invasion of ESCC cells. Based on their clinicopathological significance, LCN2 and its two expression regulators TCF7L2 and ERG1 might be therapeutic targets for ESCC.

Matrix Metalloproteinase-9 (MMP-9) as a Cancer Biomarker and MMP-9 Biosensors: Recent Advances

As one of the most widely investigated matrix metalloproteinases (MMPs), MMP-9 is a significant protease which plays vital roles in many biological processes. MMP-9 can cleave many extracellular matrix (ECM) proteins to regulate ECM remodeling. It can also cleave many plasma surface proteins to release them from the cell surface. MMP-9 has been widely found to relate to the pathology of cancers, including but not limited to invasion, metastasis and angiogenesis. Some recent research evaluated the value of MMP-9 as biomarkers to various specific cancers. Besides, recent research of MMP-9 biosensors discovered various novel MMP-9 biosensors to detect this enzyme. In this review, some recent advances in exploring MMP-9 as a biomarker in different cancers are summarized, and recent discoveries of novel MMP-9 biosensors are also presented.

Acute- and late-phase matrix metalloproteinase (MMP)-9 activity is comparable in female and male rats after peripheral nerve injury

BACKGROUND

In the peripheral nerve, pro-inflammatory matrix metalloproteinase (MMP)-9 performs essential functions in the acute response to injury. Whether MMP-9 activity contributes to late-phase injury or whether MMP-9 expression or activity after nerve injury is sexually dimorphic remains unknown.

METHODS

Patterns of MMP-9 expression, activity and excretion were assessed in a model of painful peripheral neuropathy, sciatic nerve chronic constriction injury (CCI), in female and male rats. Real-time Taqman RT-PCR for MMP-9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1) of nerve samples over a 2-month time course of CCI was followed by gelatin zymography of crude nerve extracts and purified MMP-9 from the extracts using gelatin Sepharose-beads. MMP excretion was determined using protease activity assay of urine in female and male rats with CCI.

RESULTS

The initial upsurge in nerve MMP-9 expression at day 1 post-CCI was superseded more than 100-fold at day 28 post-CCI. The high level of MMP-9 expression in late-phase nerve injury was accompanied by the reduction in TIMP-1 level. The absence of MMP-9 in the normal nerve and the presence of multiple MMP-9 species (the proenzyme, mature enzyme, homodimers, and heterodimers) was observed at day 1 and day 28 post-CCI. The MMP-9 proenzyme and mature enzyme species dominated in the early- and late-phase nerve injury, consistent with the high and low level of TIMP-1 expression, respectively. The elevated nerve MMP-9 levels corresponded to the elevated urinary MMP excretion post-CCI. All of these findings were comparable in female and male rodents.

CONCLUSION

The present study offers the first evidence for the excessive, uninhibited proteolytic MMP-9 activity during late-phase painful peripheral neuropathy and suggests that the pattern of MMP-9 expression, activity, and excretion after peripheral nerve injury is universal in both sexes.

Zinc and zinc-containing biomolecules in childhood brain tumors

Zinc ions are essential cofactors of a wide range of enzymes, transcription factors, and other regulatory proteins. Moreover, zinc is also involved in cellular signaling and enzymes inhibition. Zinc dysregulation, deficiency, over-supply, and imbalance in zinc ion transporters regulation are connected with various diseases including cancer. A zinc ion pool is maintained by two types of proteins: (i) zinc-binding proteins, which act as a buffer and intracellular donors of zinc and (ii) zinc transporters responsible for zinc fluxes into/from cells and organelles. The decreased serum zinc ion levels have been identified in patients suffering from various cancer diseases, including head and neck tumors and breast, prostate, liver, and lung cancer. On the contrary, increased zinc ion levels have been found in breast cancer and other malignant tissues. Zinc metalloproteomes of a majority of tumors including brain ones are still not yet fully understood. Current knowledge show that zinc ion levels and detection of certain zinc-containing proteins may be utilized for diagnostic and prognostic purposes. In addition, these proteins can also be promising therapeutic targets. The aim of the present work is an overview of the importance of zinc ions, zinc transporters, and zinc-containing proteins in brain tumors, which are, after leukemia, the second most common type of childhood cancer and the second leading cause of death in children after accidents.