Glycoprotein Nonmetastatic Melanoma Protein B Research Articles

Comprehensive genomic analysis contrasting primary colorectal cancer and matched liver metastases.

Recent studies have revealed that colorectal cancer (CRC) displays intratumor genetic heterogeneity, and that the cancer microenvironment plays an important role in the proliferation, invasion and metastasis of CRC. The present study performed genomic analysis on paired primary CRC and synchronous colorectal liver metastasis (CRLM) tissues collected from 22 patients using whole-exome sequencing, cancer gene panels and microarray gene expression profiling. In addition, immunohistochemical analysis was used to confirm the protein expression levels of genes identified as highly expressed in CRLM by DNA microarray analysis. The present study identified 10 genes that were highly expressed in CRLM compared with in CRC, from 36,022 probes obtained from primary CRC, CRLM and normal liver tissues by gene expression analysis with DNA microarrays. Of the 10 genes identified, five were classified as encoding 'matricellular proteins' [(osteopontin, periostin, thrombospondin-2, matrix Gla protein (MGP) and glycoprotein nonmetastatic melanoma protein B (GPNMB)] and were selected for immunohistochemical analysis. Osteopontin was strongly expressed in CRLM (6 of 22 cases: 27.3%), but not in CRC (0 of 22: 0%; P=0.02). Periostin also exhibited strong immunoreactivity in CRLM (17 of 22: 68.2%) compared with in CRC (7 of 22: 31.8%; P=0.006). Thrombospondin-2 exhibited strong immunoreactivity in both CRC and CRLM (54.5% in CRC, 45.5% in CRLM; P=0.55). GPNMB and MGP were rarely positive for both CRC and CRLM. A comparison of immunoreactive positive factors for these five genes revealed the complexities of gene expression in CRLM. Of the cases examined, 16 (72.7%) cases of CRC showed zero or only one positive immunoreactive factor. By contrast, CRLM showed more frequent and multiple immunoreactive factors; for example, 16 cases (72.7%) shared two or more factors, which was statistically more frequent than in CRC (P=0.007). The present study revealed the genomic heterogeneity between paired primary CRC and CRLM, in terms of cancer cell microenvironment. This finding may lead to novel diagnostic and therapeutic targets in the era of genome-guided personalized cancer treatment.

N-glycosylated GPNMB ligand independently activates mutated EGFR signaling and promotes metastasis in NSCLC.

Lung cancer is the leading cause of cancer‐related death worldwide. As well as the identified role of epidermal growth factor receptor (EGFR), its association with driver mutations has improved the therapeutics for patients with lung cancer harboring EGFR mutations. These patients usually display shorter overall survival and a higher tendency to develop distant metastasis compared with those carrying the wild‐type EGFR. Nevertheless, the way to control mutated EGFR signaling remains unclear. Here, we performed membrane proteomic analysis to determine potential components that may act with EGFR mutations to promote lung cancer malignancy. Expression of transmembrane glycoprotein non‐metastatic melanoma protein B (GPNMB) was positively correlated with the status of mutated EGFR in non‐small‐cell lung cancer (NSCLC). This protein was not only overexpressed but also highly glycosylated in EGFR‐mutated, especially EGFR‐L858R mutated, NSCLC cells. Further examination showed that GPNMB could activate mutated EGFR without ligand stimulation and could bind to the C‐terminus of EGFR, assist phosphorylation at Y845, turn on downstream STAT3 signaling, and promote cancer metastasis. Moreover, we also found that Asn134 (N134) glycosylation of GPNMB played a crucial role in this ligand‐independent regulation. Depleting N134‐glycosylation on GPNMB could dramatically inhibit binding of GPNMB to mutated EGFR, blocking its downstream signaling, and ultimately inhibiting cancer metastasis in NSCLC. Clarifying the role of N‐glycosylated GPNMB in regulating the ligand‐independent activation of mutated EGFR may soon give new insight into the development of novel therapeutics for NSCLC.

Long non\u2010coding RNA MALAT1 regulates cell proliferation and apoptosis via miR-135b-5p/GPNMB axis in Parkinson\u2019s disease cell model

BackgroundsParkinson’s disease (PD) is a common age-related neurodegenerative disorder worldwide. This research aimed to investigate the effects and mechanism underlying long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in PD.MethodsSK-N-SH and SK-N-BE cells were treated with MPP+ to establish the MPP+-stimulated cell model of PD, and MALAT1 expression was determined. Then, the effects of MALAT1 depletion on cell proliferation and apoptosis were determined in the MPP+-stimulated cell model of PD. Besides, the correlations between microRNA-135b-5p (miR-135b-5p) and MALAT1 or glycoprotein nonmetastatic melanoma protein B (GPNMB) in MPP+-stimulated cell model of PD were explored.ResultsMALAT1 was increasingly expressed and downregulation of MALAT1 promoted cell proliferation while inhibited apoptosis in MPP+-stimulated cells. Besides, miR-135b-5p was a target of MALAT1 and directly targeted to GPNMB. Further investigation indicated that suppression of MALAT1 regulated cell proliferation and apoptosis by miR-135b-5p/GPNMB axis.ConclusionOur findings reveal that MALAT1/miR-135b-5p/GPNMB axis regulated cell proliferation and apoptosis in MPP+-stimulated cell model of PD, providing a potential biomarker and therapeutic target for PD.

Intracerebroventricular Treatment with 2-Hydroxypropyl-β-Cyclodextrin Decreased Cerebellar and Hepatic Glycoprotein Nonmetastatic Melanoma Protein B (GPNMB) Expression in Niemann-Pick Disease Type C Model Mice.

Niemann–Pick disease type C (NPC) is a recessive hereditary disease caused by mutation of the NPC1 or NPC2 gene. It is characterized by abnormality of cellular cholesterol trafficking with severe neuronal and hepatic injury. In this study, we investigated the potential of glycoprotein nonmetastatic melanoma protein B (GPNMB) to act as a biomarker reflecting the therapeutic effect of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) in an NPC mouse model. We measured serum, brain, and liver expression levels of GPNMB, and evaluated their therapeutic effects on NPC manifestations in the brain and liver after the intracerebroventricular administration of HP-β-CD in Npc1 gene-deficient (Npc1−/−) mice. Intracerebroventricular HP-β-CD inhibited cerebellar Purkinje cell damage in Npc1−/− mice and significantly reduced serum and cerebellar GPNMB levels. Interestingly, we also observed that the intracerebral administration significantly reduced hepatic GPNMB expression and elevated serum ALT in Npc1−/− mice. Repeated doses of intracerebroventricular HP-β-CD (30 mg/kg, started at 4 weeks of age and repeated every 2 weeks) drastically extended the lifespan of Npc1−/− mice compared with saline treatment. In summary, our results suggest that GPNMB level in serum is a potential biomarker for evaluating the attenuation of NPC pathophysiology by intracerebroventricular HP-β-CD treatment.

Elevated Circulating Levels of Glycoprotein Non-Metastatic Melanoma Protein B as a Predictor of Gestational Diabetes Mellitus.

The current study aims to investigate the differences of glycoprotein non-metastatic melanoma protein B (GPNMB) levels between gestational diabetes mellitus (GDM) women and normal blood glucose women during pregnancy to provide the basis for early intervention and treatment of GDM. The level of GPNMB was detected using an enzyme-linked immunosorbent assay (ELISA). Pearson's correlation assay was performed to analyze the correlation between serum GPNMB and fasting plasma glucose (FPG) or hemoglobin A1c (HbA1c). The receiver operating characteristic (ROC) curve was carried out to analyze the diagnostic value of serum GPNMB. Our data showed that the serum GPNMB level in GDM group was higher than that in normal blood glucose group at 5 - 12 weeks, 13 - 23 weeks, and 24 - 28 weeks of gestation, but there was no significant difference at 29 - 37 weeks of gestation. Meanwhile, the total level of serum GPNMB in GDM group was significantly higher than that in normal blood glucose group. Further study indicated that serum GPNMB positively correlated with FPG (r = 0.562, p < 0.0001) or HbA1c (r = 0.652, p < 0.0001). ROC analysis showed that serum GPNMB level at 13 - 23 weeks of gestation had a good predictive effect on predicting GDM at 24 weeks of gestation and beyond. When the cutoff value of serum GPNMB level was 2.46 µg/L, the sensitivity and specificity were 80% and 72%, respectively. The serum GPNMB level at 13 - 23 weeks of gestation is an independent risk factor for GDM in 24 weeks and beyond, and early inhibition with GPNMB may provide a preventive measure in GDM women.

Cell type-specific lipid storage changes in Parkinson’s disease patient brains are recapitulated by experimental glycolipid disturbance

Neurons are dependent on proper trafficking of lipids to neighboring glia for lipid exchange and disposal of potentially lipotoxic metabolites, producing distinct lipid distribution profiles among various cell types of the central nervous system. Little is known of the cellular distribution of neutral lipids in the substantia nigra (SN) of Parkinson's disease (PD) patients and its relationship to inflammatory signaling. This study aimed to determine human PD SN neutral lipid content and distribution in dopaminergic neurons, astrocytes, and microglia relative to age-matched healthy subject controls. The results show that while total neutral lipid content was unchanged relative to age-matched controls, the levels of whole SN triglycerides were correlated with inflammation-attenuating glycoprotein non-metastatic melanoma protein B (GPNMB) signaling in human PD SN. Histological localization of neutral lipids using a fluorescent probe (BODIPY) revealed that dopaminergic neurons and midbrain microglia significantly accumulated intracellular lipids in PD SN, while adjacent astrocytes had a reduced lipid load overall. This pattern was recapitulated by experimental in vivo inhibition of glucocerebrosidase activity in mice. Agents or therapies that restore lipid homeostasis among neurons, astrocytes, and microglia could potentially correct PD pathogenesis and disease progression.

Preliminary screening of gastric cancer related transcripts based on nanometric magnetic beads

The aim of this study was to use current genomics methodologies to screen for gastric cancer (GC)-related gene expression and to compare expression levels associated with GC and paracancerous tissues. These findings will be considered together with patient clinicopathological data with the goal of identifying new tumor markers and novel directions for diagnosis and treatment. GC-associated gene expression profiles were identified in the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases; these resources facilitated identification of genes that were differentially expressed in GC and adjacent normal tissues. Genomics screening identified ∼49 genes that were expressed at comparatively high levels and 65 genes that were expressed at comparatively low levels in association with GC. Moreover, specimens from fifty-six patients diagnosed with GC who underwent gastrointestinal surgery between March 2017 to September 2018 were used to generate RNA that was evaluated by real-time fluorescence quantitative PCR in order to confirm differential expression of genes encoding orosomucoid 1 (ORM1), hepsin (HPN), uridine phosphorylase 1 (UPP1), and glycoprotein nonmetastatic melanoma protein B (GPNMB). The nucleic acid of these samples was extracted by nanometric magnetic bead method. Among our findings, GPNMB was expressed at relatively high levels in association GC, while both ORM1 and HPN are expressed at relatively low levels in these tissues and expression of UPP1 remained unchanged. Taken together, our findings suggest that genomics methodologies can be used to identify differentially expressed genes in a comparison of GC to adjacent paracancerous tissue. Our findings also suggest that the transmembrane glycoprotein GPNMB may play a role in promoting the incidence and development of GC.

The Association Analysis of GPNMB rs156429 With Clinical Manifestations in Chinese Population With Parkinson's Disease.

Background: The mechanisms of Parkinson's disease (PD) include complicated genetic factors. The roles of newly found risk genes need to be further verified among different ethnicities. In a two-stage meta-analysis, single nucleotide polymorphism (SNP) of rs156429 in glycoprotein non-metastatic melanoma protein B (GPNMB) was reported to be associated with PD. So far clinical studies have focused on association between rs156429 and PD onset, however there is little evidence linking rs156429 with PD symptoms.Objective: This study aimed to investigate the possible association of GPNMB rs156429 with PD manifestations among southeastern Chinese people.Methods: Demographic variables, disease-related factors, and motor and non-motor assessments of 511 PD patients were collected. Polymerase chain reaction (PCR) and SNaPshot technique were used to detect GPNMB rs156429. The associations of rs156429 with PD rating scales and clinical manifestations were analyzed by Kruskal-Wallis test and logistic regression model separately.Results: Kruskal-Wallis test and logistic regression model failed to reveal an association between GPNMB rs156429 and scores from Montreal Cognitive Assessment (MoCA) (p = 0.037; p = 1.000 after correction), and pain symptoms of 511 PD patients (p = 0.008, OR = 0.59, 95% CI = 0.40–0.87, overdominant model after adjustment; p = 0.168 after correction, overdominant model after adjustment). However, further analysis based on genders showed that GPNMB rs156429 might have a trend for being associated with cognitive dysfunction (Mini-Mental State Examination (MMSE), p = 0.064 after correction; MoCA, p = 0.064 after correction) and pain symptoms (p = 0.063 after correction, overdominant model after adjustment) in female PD patients but not male patients.Conclusions: This study revealed that GPNMB rs156429 might have a trend for being associated with cognitive dysfunction and pain symptoms of female PD patients in the southeastern Chinese population. Further studies from a larger sample size are needed to confirm these findings.

Glycoprotein Nonmetastatic Melanoma Protein B as Potential Imaging Marker in Posttherapeutic Metastatic Head and Neck Cancer.

ObjectiveTo evaluate expression of potential molecular imaging targets epidermal growth factor receptor (EGFR), glycoprotein nonmetastatic melanoma protein B (GPNMB), and vascular endothelial growth factor (VEGF) in lymph nodes (LNs) with or without head and neck squamous cell carcinoma (HNSCC) metastases after (chemo)radiation.Study DesignRetrospective study comparing receptor expression in paired lymph nodes after initial treatment.SettingA tertiary referral hospital.Subjects and MethodsSalvage neck dissection specimens of 40 patients treated with (chemo)radiation were selected. LNs that contained viable tumor, reactive changes after initial treatment, and normal LNs were analyzed using immunohistochemically determined H-scores and by calculating sensitivity and specificity rates and positive/negative predictive values (PPVs/NPVs).ResultsEGFR expression was found in 86% and GPNMB expression in 100% of the LNs with viable tumor. VEGF expression was present in all lymph node types. For EGFR, the sensitivity rate was 86%, and specificity rate was 81%. For GPNMB, these were 100% and 75%, respectively. PPV of EGFR was 61.8% and NPV was 98.2%. These were 56.4% and 100% for GPNMB, respectively.ConclusionIn residual or recurrent HNSCC lymph node metastases, both EGFR and GPNMB show tumor-specific expression in immunohistochemistry, which may prove useful in future molecular imaging in salvage neck dissections. Immunohistochemically detected VEGF expression indicates that this target is not feasible for imaging purposes in salvage surgery. Therefore, GPNMB could be a new potential imaging target showing comparable results to EGFR in immunohistochemistry.

High expression of GPNMB indicates an unfavorable prognosis in glioma: Combination of data from the GEO and CGGA databases and validation in tissue microarray.

Glycoprotein non-metastatic melanoma protein B (GPNMB), a transmembrane glycoprotein, has been reported to be involved in tumor progression, but its prognostic value for glioma and the mechanistic effects on glioma progression have not been clearly explored. The present study aimed to investigate the prognostic role of GPNMB in glioma and the potential mechanisms of how GPNMB mediates glioma progression. Differentially expressed genes between the four highest and four lowest GPNMB expression samples in the GSE53733 dataset were first determined. Gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis and Gene set enrichment analysis results demonstrated that the significantly enriched pathways in samples with high GPNMB expression compared with those with low GPNMB expression were associated with hypoxia, angiogenesis, migration and invasion. Pearson correlation analysis was conducted to investigate the correlations between GPNMB expression and the markers of hypoxia, angiogenesis, migration and invasion in GSE53733, which were further validated using another mRNA microarray dataset from the Chinese Glioma Genome Atlas (CGGA). In addition, using the CGGA dataset, high GPNMB expression was demonstrated to be significantly associated with advanced WHO grade and short survival time in patients with glioma. Of note, based on the immunohistochemical staining of the tissue microarrays, Kaplan-Meier analysis with the Renyi test and a Cox proportional hazards model were used to validate the unfavorable prognostic role of high GPNMB expression in glioma. In conclusion, high GPNMB expression may be associated with high tumor grade and unfavorable prognosis in glioma. GPNMB expression was demonstrated to correlate with the markers of hypoxia, angiogenesis, migration and invasion, which may be potential mechanisms through which GPNMB mediates glioma progression.

Transgenic Overexpression of GPNMB Protects Against MPTP-Induced Neurodegeneration.

Parkinson's disease (PD) is a progressive neurodegenerative disease highlighted by a marked loss of dopaminergic cell loss and motor disturbances. Currently, there are no drugs that slow the progression of the disease. A myriad of factors have been implicated in the pathogenesis and progression of PD including neuroinflammation. Although anti-inflammatory agents are being evaluated as potential disease-modifying therapies for PD, none has proven effective to date, suggesting that new and novel targets are needed. Glycoprotein nonmetastatic melanoma protein B (GPNMB) is a transmembrane glycoprotein that has recently been shown to reduce inflammation in astrocytes and to be increased in post-mortem PD brain samples. Here we show that transgenic overexpression of GPNMB protects against dopaminergic neurodegeneration in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropridine mouse model of Parkinson's disease. Furthermore, GPNMB overexpression reduces gliosis and prevented microglial morphological changes following MPTP treatment compared with wild-type MPTP-treated mice. Additionally, recombinant GPNMB attenuates LPS-induced inflammation in primary mouse microglia. These results suggest a neuroprotective and anti-inflammatory role for GPNMB and warrant further investigation for GPNMB as a novel therapy for PD.

Altered expression of glycoprotein non‑metastatic melanoma protein B in the distal sciatic nerve following injury.

Glycoprotein non-metastatic melanoma protein B (GPNMB) exerts neuroprotective effects on amyotrophic lateral sclerosis and cerebral ischemia reperfusion injury in the central nervous system. However, the expression and function of GPNMB in the peripheral nervous system, particularly following peripheral nerve injury, remains unknown. In the present study, the mRNAs and long non-coding RNAs of the distal sciatic nerve were profiled via microarray analysis at days 0, 1, 3, 7, 14, 21 and 28 following transection. The results revealed that the expression of GPNMB mRNA was similar to the proliferation tendency of distal acute denervated Schwann cells (SCs), the results of which were further validated by reverse transcription quantitative polymerase chain reaction, western blot analysis and immunohistochemistry. To investigate the function of GPNMB on SCs, recombinant human GPNMB (rhGPNMB) was added to cultured denervated SCs from the distal stumps of transected sciatic nerve. The proliferation, expression and secretion of neurotrophic factors (NTFs) and neural adhesion molecules (NAMs) were subsequently detected. The results demonstrated that GPNMB expression was increased in distal sciatic nerve following transection in vivo, while rhGPNMB promoted the proliferation of SCs as well as expression and secretion of NTFs and NAMs in vitro. Therefore, GPNMB could be a novel strategy for peripheral nerve regeneration.

Targeted Multiple Reaction Monitoring Analysis of CSF Identifies UCHL1 and GPNMB as Candidate Biomarkers for ALS

The neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and Parkinson’s disease (PD) share some common molecular deficits including disruption of protein homeostasis leading to disease-specific protein aggregation. While insoluble protein aggregates are the defining pathological confirmation of diagnosis, patient stratification based on early molecular etiologies may identify distinct subgroups within a clinical diagnosis that would respond differently in therapeutic development programs. We are developing targeted multiple reaction monitoring (MRM) mass spectrometry methods to rigorously quantify CSF proteins from known disease genes involved in lysosomal, ubiquitin-proteasomal, and autophagy pathways. Analysis of CSF from 21 PD, 21 ALS, and 25 control patients, rigorously matched for gender, age, and age of sample, revealed significant changes in peptide levels between PD, ALS, and control. In patients with PD, levels of two peptides for chromogranin B (CHGB, secretogranin 1) were significantly reduced. In CSF of patients with ALS, levels of two peptides from ubiquitin carboxy-terminal hydrolase like protein 1 (UCHL1) and one peptide each for glycoprotein non-metastatic melanoma protein B (GPNMB) and cathepsin D (CTSD) were all increased. Analysis of patients with ALS separated into two groups based on length of survival after CSF sampling revealed that the increases in GPNMB and UCHL1 were specific for short-lived ALS patients. While analysis of additional cohorts is required to validate these candidate biomarkers, this study suggests methods for stratification of ALS patients for clinical trials and identifies targets for drug efficacy measurements during therapeutic development.

545 Keratinocyte-derived glycoprotein non-metastatic melanoma protein B protects melanocytes from oxidative stress in a CD44-independent manner

Glycoprotein non-metastatic melanoma protein B (GPNMB) is a Type I transmembrane glycoprotein which has important roles in cancer and amyotrophic lateral sclerosis (ALS). In skin epidermis, GPNMB is mainly expressed in melanocytes and plays a critical role in pigmentation. Previously, we showed that GPNMB was highly expressed in keratinocytes from healthy donors, but decreased in vitiligo lesions. The function of keratinocyte-derived GPNMB is yet to be known. Therefore, we first confirmed GPNMB expression in cultured normal human epidermal keratinocytes, and oxidative stress (H2O2) down-regulated both membrane GPNMB and soluble GPNMB (sGPNMB) expression. Then, we found sGPNMB had protective effect to melanocytes against oxidative stress. Furthermore, sGPNMB was reported to have neuroprotective effect via CD44 receptor. However, after siRNA-mediated knockdown of CD44 in melanocytes, the protective effect of sGPNMB was not altered. These findings strongly suggest that the oxidative stress-induced down-regulation of GPNMB in keratinocytes is involved in vitiligo, taking it into account that GPNMB disappeared in epidermal keratinocytes of vitiligo skins and sGPNMB protected melanocytes from oxidative stress. Furthermore, not CD44 but another novel receptor may be expressed for the GPNMB extracellular fragment in melanocytes, suggesting that this novel pathway may represent a molecular target to improve vitiligo therapy.

546 Increased Number of M2 Macrophages and High Expression of Macrophage-Derived Glycoprotein Non-Metastatic Melanoma Protein B in Vitiliginous Skin

Macrophages, an essential component of immune system, play a critical role not only in inflammation but also in wound healing. There are two subtypes of macrophages, M1 macrophages which encourage inflammation and M2 macrophages which decrease inflammation and encourage tissue repair. Glycoprotein non-metastatic melanoma protein b (GPNMB) is a glycosylated transmembrane protein which is highly expressed in multiple cells, including macrophages. GPNMB is also reported to act as a negative regulator of macrophage inflammatory responses in Alzheimer diseases and Parkinson diseases. Previous study has also shown the presence of macrophages in vitiligo skin. However, the role of macrophage-derived GPNMB in vitiligo is still unknown. In this study, using skin tissues from healthy donors and vitiligo patients, the expression of CD163(a marker of M2 macrophages) and GPNMB were analyzed by double immunofluorescence staining. The results showed that more M2 macrophages existed in vitiligo skin, compared with healthy skin. Furthermore, increased expression of GPNMB was observed in M2 macrophages from skin of patients with vitiligo, compared with that from healthy skin. In in vitro study, recombinant GPNMB protected cultured melanocytes against oxidative stress, i.e. UV irradiation or chemical stimuli. These findings suggest that increased M2 macrophages and macrophage-derived GPNMB might be involved in the pathogenesis of vitiligo.

CSE1L silence inhibits the growth and metastasis in gastric cancer by repressing GPNMB via positively regulating transcription factor MITF.

Human chromosomal segregation 1-like (CSE1L) gene functions as a key molecular mediator in cellular proliferation, invasion, and apoptosis. The association of CSE1L with tumor progression has been reported in diverse human cancers. A greater understanding of CSE1L molecular mechanism is beneficial for cancer treatment. In the current study, we show that CSE1L was highly expressed in gastric cancer (GC) cell lines. CSE1L silence promoted apoptosis and inhibited cell proliferation and invasion. Overexpression of glycoprotein nonmetastatic melanoma protein B (GPNMB) reversed the anticancer effect of CSE1L inhibition. CSE1L inhibition decreased GPNMB by microphthalmia-associated transcription factor (MITF). Moreover, GPNMB regulates the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway. Taken together, our study revealed that CSE1L inhibition decreased MITF and suppressed GPNMB expression, thereby activating the PI3K/Akt/mTOR and MEK/ERK signaling pathway, ultimately inhibiting the tumor growth and metastasis in GC.

Microglia express GPNMB in the brains of Alzheimer's disease and Nasu-Hakola disease.

Glycoprotein non-metastatic melanoma protein B (GPNMB) is a type I transmembrane glycoprotein first identified in low-metastatic human melanoma cell lines as a regulator of tumor growth. GPNMB is widely expressed in various tissues, where it is involved in cell differentiation, migration, inflammation/anti-inflammation, tissue regeneration, and neuroprotection. GPNMB is identified in microglia of adult rat brains, neurons and astrocytes of GPNMB transgenic (Tg) mouse brains, and motor neurons of amyotrophic lateral sclerosis (ALS) patients. Nasu-Hakola disease (NHD) is a rare autosomal recessive disorder, characterized by progressive presenile dementia and formation of multifocal bone cysts, caused by genetic mutations of either TYROBP (DAP12) or TREM2. TREM2 and DAP12 constitute a receptor/adaptor signaling complex expressed exclusively on osteoclasts, dendritic cells, macrophages, and microglia. Pathologically, the brains of NHD patients exhibit leukoencephalopathy, astrogliosis, accumulation of axonal spheroids, and remarkable activation of microglia predominantly in the white matter of frontal and temporal lobes and the basal ganglia. At present, molecular mechanisms responsible for development of leukoencephaolpathy in NHD brains remain totally unknown. Recent evidence indicates that disease-associated microglia (DAM) that cluster around amyloid plaques express high levels of GPNMB in Alzheimer's disease (AD) brains. Because microglia act as a key regulator of leukoencephalopathy in NHD brains, it is proposed that GPNMB expressed on microglia might play a protective role in progression of leukoencephalopathy possibly via active phagocytosis of myelin debris. In the present study using immunohistochemistry, we have attempted to clarify the expression of GPNMB in NHD brains, compared with AD brains. We found that microglia accumulating in the white matter express an intense GPNMB immunoreactivity in both NHD and AD brains, suggesting that the accumulation of GPNMB-immunoreactive microglia is a general phenomenon in neurodegenerative brains.

Transgenic Overexpression of GPNMB Protects Against MPTP‐Induced Neurodegeneration

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease worldwide behind Alzheimer's disease. One feature of PD is the marked loss of dopaminergic neurons leading to diminished release of dopamine into the basal ganglia, leading to motor dysfunction. Diminished dopamine release manifests as the hallmark symptoms of Parkinson's disease: resting tremor, rigidity, bradykinesia, and akinesia. Currently, there are no therapies to effectively slow disease progression, thus, novel drug discovery is of paramount importance. GPNMB is a transmembrane glycoprotein, with reported anti‐inflammatory, reparative, and neuroprotective functions. GPNMB has reported neuroprotective functions in mouse models of cerebral ischemia/reperfusion and amyotrophic lateral sclerosis (ALS). Here, we aimed to investigate GPNMB's neuroprotective ability in an acute 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) mouse model of Parkinson's disease. For this investigation we utilized 10–12‐week‐old male transgenic mouse overexpressing GPNMB (GPNMB‐TG) and age‐matched male C57 Black/6N wild‐type mice. Control mice were injected with saline, while MPTP‐treated mice were treated with 15 mg/kg of MPTP. Mice were injected every two hours, a total of four times and sacrificed one week after the last injection, and midbrain and striatum were collected for HPLC, western blot, and histological analyses. An additional study followed the same paradigm, but mice were sacrificed two days after the final injection in order to assess the effects of GPNMB overexpression on inflammation. Western blot analysis of the striatum revealed a significantly elevated level of tyrosine hydroxylase and dopamine active transporter in GPNMB‐TG MPTP‐treated mice compared to C57 MPTP‐treated mice. Additionally, MPTP‐induced neuron loss was attenuated in GPNMB‐TG mice compared to wild‐type mice. Furthermore, we have shown that GPNMB‐TG MPTP‐treated mice have reduced gliosis and inflammation compared to wild‐type MPTP‐treated mice. This indicates that GPNMB may play a role in microglia and led us to investigate this role. We show that recombinant GPNMB (rGPNMB) reduces the inflammatory response in primary microglia cultures following lipopolysaccharide (LPS) treatment. Specifically, rGPNMB significantly reduces the gene expression of pro‐inflammatory cytokines and rescues the loss of anti‐inflammatory gene expression following LPS treatment. Furthermore, rGPNMB reduces nitric oxide production following LPS treatment in primary microglia. Taken together, these results suggest that GPNMB is neuroprotective in the acute MPTP mouse model of PD by acting as an anti‐inflammatory agent. The mechanism by which GPNMB inhibits inflammation in microglia is currently being investigated by our laboratory.Support or Funding InformationNIH (RO1ES021800) and the Michael J Fox Foundation for Parkinson's Disease Research to Jason R. Richardson. Additional support was provided through generous donations from the Glenn and Karen Leppo, the Richard Nicely, and the Allan and Janice Woll Parkinson's Research Funds.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Glycoprotein Nonmetastatic Melanoma Protein B (GPNMB) Ameliorates the Inflammatory Response in Periodontal Disease.

Glycoprotein nonmetastatic melanoma protein B (GPNMB) is a type I transmembrane protein that can modulate osteoblasts and bone mineralization. Periodontal disease (PD) is characterized by gum inflammation, alveolar bone resorption, and tooth loss. In this study, we found that GPNMB is highly expressed in inflamed periodontal tissue through microarray and immunohistochemistry (IHC) assays. The role of GPNMB in the pathogenesis of PD was evaluated with primary human periodontal ligament cells (hPDLCs) treated with lipopolysaccharide (LPS) and a GPNMB-expressing lentivirus (lenti-GP). In the hPDLCs treated with LPS and lenti-GP, the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6 was suppressed and that of IL-10 was upregulated. GPNMB significantly decreased apoptosis in the hPDLCs treated with LPS. GPNMB could upregulate the expression of Jumonji domain-containing protein 3 (Jmjd3), a histone 3 lysine 27 (H3K27) demethylase that is linked to the modulation of the inflammatory response and apoptosis. Taken together, our data find that GPNMB is highly expressed in gum tissue with PD and may be an anti-inflammatory player in the pathogenesis of PD.

Glycoprotein nonmetastatic melanoma protein B accelerates tumorigenesis of cervical cancer in vitro by regulating the Wnt/β-catenin pathway.

Cervical cancer is one of the most common cancers among women around the world. However, the underlying mechanism involved in cervical cancer progression is incompletely known. In the present study, we determined the role of glycoprotein nonmetastatic melanoma protein B (GPNMB) in tumorigenesis of cervical cancer. According to the GEO database, we found that GPNMB expression was significantly higher in cervical cancer than in normal cervix epithelium. A similar pattern was observed in GPNMB expression in cultured cervical cancer cells and normal cervical epithelial cells. Compared with the control, GPNMB knockdown significantly decreased the proliferation and migration capacity, but enhanced the apoptosis capacity of SiHa and HeLa cells. Additionally, the activity of MMP-2 and MMP-9 were aberrantly increased in SiHa and HeLa cells compared with normal cervical epithelial cells, whereas their activities were strongly inhibited by GPNMB siRNA. Furthermore, Wnt/β-catenin signaling was activated by GPNMB in SiHa and HeLa cells. Increased MMP-2/MMP-9 expression was suppressed by Dkk-1, inhibitor of Wnt/β-catenin signaling, while it was enhanced by stimulator BIO. The proliferation, migration, and apoptosis capacity of HeLa cells were found to be affected by Dkk-1 and BIO to different extents. In conclusion, we demonstrated that GPNMB contributed to the tumorigenesis of cervical cancer, at least in part, by regulating MMP-2/MMP-9 activity in tumor cells via activation of canonical Wnt/β-catenin signaling. This might be a potential therapeutic target for treating human cervical cancer.