Glycoprotein Non-metastatic B Research Articles

Secretion of GPNMB from Neural Stem Cells Induced by ET-1 Contributes to Angiogenesis after Spinal Cord Injury.

The feeble plasticity of spinal cord microvascular endothelial cells (SCMECs) after trauma is one of the major causes of spinal cord injury (SCI). Neural stem cells (NSCs) play an important role in nerve repair. Glycoprotein nonmetastatic B (GPNMB) has neuroprotective effects and can be stimulated by endothelin 1 (ET-1), and its expression is upregulated in SCI. Here, we aim to investigate whether elevated ET-1 levels stimulate NSCs to secrete GPNMB, thereby further promoting angiogenesis. Mouse SCMECs and NSCs were isolated, cultured, and identified by flow cytometry and immunofluorescence staining. NSCs were treated with ET-1, while SCMECs were cocultured with NSCs, followed by treatment with ET-1. NCS and SCMEC viability were evaluated using cell counting kit 8 (CCK-8) assay, while cell proliferation, migration, invasion, and angiogenesis were examined using 5'-Ethynyl-2'-Deoxyuridine (EdU) staining, wound healing assay, Transwell assay, and tube formation assay. GPNMB expression in NCSs and SCMECs was quantified by western blot assay, quantitative Real-Time polymerase chain reaction (qRT-PCR), or enzyme-linked immunosorbent assay (ELISA). Mouse SCMECs and NSCs were successfully isolated and cultured. ET-1 promoted NSC viability and proliferation and upregulated GPNMB expression. NSCs and ET-1-treated NSCs promoted the viability, migration, invasion, angiogenesis, and GPNMB expression in SCMECs compared with control group cells, while GPNMB antibody reversed the above effects of ET-1 on the SCMECs. ET-1 promotes SCMEC migration and invasion, along with angiogenesis, by enhancing NSC-mediated GPNMB secretion, so ET-1 may be a novel therapeutic target for SCI.

Recurrent Tuberous Sclerosis Complex/Mammalian Target of Rapamycin Mutations Define Primary Renal Hemangioblastoma as a Unique Entity Distinct From Its Central Nervous System Counterpart.

Renal hemangioblastoma (HB) is a rare subset of HBs arising outside of the central nervous system (CNS), with its molecular drivers remaining entirely unknown. There were no significant alterations detected in previous studies, including von Hippel-Lindau gene alterations, which are commonly associated with CNS-HB. This study aimed to determine the real molecular identity of renal HB and better understand its relationship with CNS-HB. A cohort of 10 renal HBs was submitted for next-generation sequencing technology. As a control, 5 classic CNS-HBs were similarly analyzed. Based on the molecular results, glycoprotein nonmetastatic B (GPNMB) immunohistochemistry was further performed in the cases of renal HB and CNS-HB. Mutational analysis demonstrated that all 10 renal HBs harbored somatic mutations in tuberous sclerosis complex 1 ( TSC1 , 5 cases), TSC2 (3 cases), and mammalian target of rapamycin (2 cases), with the majority classified as pathogenic or likely pathogenic. The CNS-HB cohort uniformly demonstrated somatic mutations in the von Hippel-Lindau gene. GPNMB was strong and diffuse in all 10 renal HBs and completely negative in CNS-HBs, reinforcing the molecular findings. Our study reveals a specific molecular hallmark in renal HB, characterized by recurrent TSC/mammalian target of rapamycin mutations, which defines it as a unique entity distinct from CNS-HB. This molecular finding potentially expands the therapeutic options for patients with renal HB. GPNMB can be considered for inclusion in immunohistochemical panels to improve renal HB identification.

Investigating the role and regulation of GPNMB in progranulin-deficient macrophages.

Progranulin (PGRN) is a holoprotein that is internalized and taken to the lysosome where it is processed to individual granulins (GRNs). PGRN is critical for successful aging, and insufficient levels of PGRN are associated with increased risk for developing neurodegenerative diseases like AD, PD, and FTD. A unifying feature among these diseases is dysregulation of peripheral immune cell populations. However, considerable gaps exist in our understanding of the function(s) of PGRN/GRNs in immune cells and their role in regulating central-peripheral neuroimmune crosstalk. One of the most upregulated genes and proteins in humans with GRN haploinsufficiency and in aged Grn knock-out (KO) mice is glycoprotein non-metastatic B (GPNMB) but its normal role within the context of immune crosstalk has not been elucidated. To address this gap, peritoneal macrophages (pMacs) from 5-to-6-month old WT and Grn KO mice were assessed for Gpnmb expression and stimulation-dependent cytokine release in the presence or absence of the Gpnmb extracellular domain (ECD). Cellular localization, as well as inhibition of, the microphthalmia-associated transcription factor (MITF) was assessed to determine its mechanistic role in Gpnmb overexpression in Grn KO pMacs. We observed an increase in GPNMB protein and mRNA as a result of insufficient progranulin in peripheral immune cells at a very early age relative to previous reports on the brain. Stimulation-dependent cytokine release was decreased in the media of Grn KO pMacs relative to WT controls; a phenotype that could be mimicked in WT pMacs with the addition og GPNMB ECD. We also found that MITF is dysregulated in Grn KO pMacs; however, its nuclear translocation and activity are not required to rescue the immune dysregulation of Grn KO macrophages, suggesting redundancy in the system. These findings highlight the fact that knowledge of early-stage disease mechanism(s) in peripheral populations may inform treatment strategies to delay disease progression at an early, prodromal timepoint prior to development of neuroinflammation and CNS pathology.

Investigating the role of GPNMB in modulating LPS mediated inflammation in progranulin‐deficient macrophages

AbstractBackgroundProgranulin (PGRN) is a glycosylated holoprotein that is critical to endo‐lysosomal health and regulating inflammatory responses over the lifespan. Insufficient PGRN due to nonsense mutations in the GRN gene has been linked to increased risk of developing Frontotemporal Dementia (FTD) and Neuronal Ceroid Lipofuscinosis (NCL‐11). The precise mechanism(s) behind the onset and progression of disease is unclear, and no disease‐modifying treatment exists. Previous work has identified increased glycoprotein non‐metastatic B (GPNMB) in both the cortex and plastma of Grn−/− mice relative to Grn+/+ mice, and our lab has recently identified different GPNMB expression in PGRN‐deficient immune cell populations, but it remains unclear how this increase in GPNMB modifies the inflammatory response(s) with PGRN deficits. This work seeks to investigate GPNMB expression over the course of the immune response in PGRN‐deficient cells, and the extent to which GPNMB modulates inflammation.MethodTo investigate the role(s) of GPNMB in PGRN‐deficient myeloid cells, we isolated peritoneal macrophages (pMacs) from Grn+/+,and Grn−/− mice and quantified GPNMB protein before and after lipopolysaccharide (LPS) stimulation with western blot. We also determined the extent to which exposure to the GPNMB extracellular domain (ECD) modifies LPS‐elicited markers of inflammation in both Grn+/+and Grn−/‐ pMacs via qPCR. Finally, we determined how markers of inflammation were altered in pMacs from Grn−/−Gpmnb−/‐ relative to Grn+/+and Grn−/‐ with and without LPS stimulation.ResultWe determined that the additional loss of GPNMB in Grn−/−Gpmnb−/− pMacs altered the expression of inflammatory markers after LPS challenge relative to both Grn−/−and Grn+/+ pMacs. We also discovered that GPNMB is dynamically regulated during and after LPS challenge in both Grn+/+ and Grn−/− pMacs. Finally, we determined that the addition of GPNMB ECD before and during LPS treatment ameliorated the altered expression of inflammatory markers during LPS challenge.ConclusionThe increase of GPNMB expression in Grn−/‐ myeloid cells is a significant modulator of inflammatory responses and may be a potential target in the development of therapeutics.

Positive GPNMB Immunostaining Differentiates Renal Cell Carcinoma With Fibromyomatous Stroma Associated With TSC1/2/MTOR Alterations From Others.

Renal cell carcinoma with fibromyomatous stroma (RCCFMS) include ELOC/TCEB1 -mutated renal cell carcinoma (RCC) and those with TSC1/2 / MTOR alterations. Besides morphologic similarity, most of these tumors is known to be diffusely positive for carbonic anhydrase IX and cytokeratin 7 by immunohistochemistry. We previously showed strong and diffuse expression of GPNMB (glycoprotein nonmetastatic B) in translocation RCC and eosinophilic renal neoplasms with known TSC1/2/MTOR alterations. We retrospectively identified molecularly confirmed cases of TCEB1/ELOC -mutated RCC (7 tumors from 7 patients), and RCCFMS with alterations in TSC1/2/MTOR (6 tumors from 5 patients, 1 patient with tuberous sclerosis syndrome). In addition, we included 7 clear cell papillary renal cell tumors (CCPRCTs) and 8 clear cell RCC, as they can also present morphologic overlap with RCCFMS. Morphologically, RCCs with TSC1/2/MTOR alterations and those with TCEB1/ELOC mutations were indistinguishable and characterized by papillary, nested, or tubular architecture, with tumor cells with clear cytoplasm and low nuclear grade. By immunohistochemistry, cytokeratin 7 was positive in 5/7 (71%) of TCEB1/ELOC -mutated RCCs, 6/6 (100%) of RCCs with TSC1/2/mTOR alterations, and 7/7 (100%) of CCPRCTs ( P =not significant). Carbonic anhydrase IX was positive in 7/7 TCEB1/ELOC -mutated RCCs, 6/6 (100%) of RCCs with TSC1/2/MTOR alterations, and 7/7 (100%) of CCPRCTs ( P =NS). GPNMB was strongly and diffusely positive in all tumors with TSC1/2/MTOR alterations (6/6), while negative in all TCEB1/ELOC -mutated RCCs (0/6), or CCPRCTs (0/7) ( P =0.002). Two of 8 clear cell RCC showed focal weak staining, while 6/8 were negative. In conclusion, the results support the use of GPNMB to distinguish RCCFMS with TSC1/2/MTOR alterations from others with similar morphology.

Molecularly Imprinted Nanobeacons Redirect Innate Immune Killing towards Triple Negative Breast Cancer

AbstractHarnessing innate immunity is an appealing strategy for cancer treatment. Herein, we report a new strategy called molecularly imprinted nanobeacons (MINBs) for redirecting innate immune killing towards triple‐negative breast cancer (TNBC). The MINBs were molecularly imprinted nanoparticles with the N‐epitope of glycoprotein nonmetastatic B (GPNMB) as the template and grafted with plentiful fluorescein moieties as the hapten. The MINBs could tag the TNBC cells via binding with GPNMB and thereby provide navigation for recruiting hapten‐specific antibodies. The gathered antibodies could further trigger effective Fc‐domain‐mediated immune killing towards the tagged cancer cells. In vivo experiments showed that the TNBC growth was significantly inhibited after MINBs treatment by intravenous injection as compared with control groups. This study not only opens a new access for redirecting innate immunity towards TNBC but also paves the way for innate immunity‐based therapy of other diseases.

Molecularly Imprinted Nanobeacons Redirect Innate Immune Killing towards Triple Negative Breast Cancer.

Harnessing innate immunity is an appealing strategy for cancer treatment. Herein, we report a new strategy called molecularly imprinted nanobeacons (MINBs) for redirecting innate immune killing towards triple-negative breast cancer (TNBC). The MINBs were molecularly imprinted nanoparticles with the N-epitope of glycoprotein nonmetastatic B (GPNMB) as the template and grafted with plentiful fluorescein moieties as the hapten. The MINBs could tag the TNBC cells via binding with GPNMB and thereby provide navigation for recruiting hapten-specific antibodies. The gathered antibodies could further trigger effective Fc-domain-mediated immune killing towards the tagged cancer cells. In vivo experiments showed that the TNBC growth was significantly inhibited after MINBs treatment by intravenous injection as compared with control groups. This study not only opens a new access for redirecting innate immunity towards TNBC but also paves the way for innate immunity-based therapy of other diseases.

Integrated single-cell transcriptomic analyses reveal that GPNMB-high macrophages promote PN-MES transition and impede T cell activation in GBM.

SummaryBackgroundGlioblastoma (GBM) is the most aggressive type of primary brain tumor and is often resistant to current therapies. Tumor microenvironment-centered therapies may unleash new hope for GBM treatment. Therefore, an in-depth understanding of tumor-stroma communication is urgently needed to identify promising therapeutic targets.MethodsWe systematically analyzed GBM single-cell RNA sequencing (scRNA-seq), bulk RNA-seq and spatial scRNA-seq data from various human and mice studies to characterize the network within the microenvironment. Moreover, we applied ex vivo co-culture system, flow cytometry analysis and immunofluorescent staining to validate our findings.FindingsOur integrative analyses revealed that highly heterogeneous GBM tumor cells can be classified into MES-like, AC-like, OPC-like and NPC-like subtypes based on molecular studying. Additionally, trajectory and regulatory network inference implied a PN to MES cell state transition regulated by specific transcriptional factor (TF) regulons. Importantly, we discovered that glycoprotein nonmetastatic B (GPNMB) derived from macrophages played a crucial role in this transition through immune cell-tumor interplay. Besides, through deep signal transduction analyses and cell co-culture studies, we further disclosed that these GPNMB-high macrophage subpopulations, originating from monocytes, could also ineffectively retain T cells from activating by dendritic cells (DCs).InterpretationOur study suggests that targeting this particular GPNMB-high macrophage subset may provide a new strategy to control GBM plasticity and facilitate T cell-based immunotherapy.FundingA full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

GPNMB expression identifies TSC1/2/mTOR-associated and MiT family translocation-driven renal neoplasms.

GPNMB (glycoprotein nonmetastatic B) and other TFE3/TFEB transcriptional targets have been proposed as markers for microphthalmia (MiT) translocation renal cell carcinomas (tRCCs). We recently demonstrated that constitutive mTORC1 activation via TSC1/2 loss leads to increased activity of TFE3/TFEB, suggesting that the pathogenesis and molecular markers for tRCCs and TSC1/2‐associated tumors may be overlapping. We examined GPNMB expression in human kidney and angiomyolipoma (AML) cell lines with TSC2 and/or TFE3/TFEB loss produced using CRISPR–Cas9 genome editing as well as in a mouse model of Tsc2 inactivation‐driven renal tumorigenesis. Using an automated immunohistochemistry (IHC) assay for GPNMB, digital image analysis was employed to quantitatively score expression in clear cell RCC (ccRCC, n = 87), papillary RCC (papRCC, n = 53), chromophobe RCC (chRCC, n = 34), oncocytoma (n = 4), TFE3‐ or TFEB‐driven tRCC (n = 56), eosinophilic solid and cystic RCC (ESC, n = 6), eosinophilic vacuolated tumor (EVT, n = 4), and low‐grade oncocytic tumor (LOT, n = 3), as well as AML (n = 29) and perivascular epithelioid cell tumors (PEComas, n = 8). In cell lines, GPNMB was upregulated following TSC2 loss in a MiT/TFE‐ and mTORC1‐dependent fashion. Renal tumors in Tsc2 +/− A/J mice showed upregulation of GPNMB compared with normal kidney. Mean GPNMB expression was significantly higher in tRCC than in ccRCC (p < 0.0001), papRCC (p < 0.0001), and chRCC (p < 0.0001). GPNMB expression in TSC1/2/MTOR alteration‐associated renal tumors (including ESC, LOT, AML, and PEComa) was comparable to that in tRCC. The immunophenotype of tRCC and TSC1/2/MTOR alteration‐associated renal tumors is highly overlapping, likely due to the increased activity of TFE3/TFEB in both, revealing an important caveat regarding the use of TFE3/TFEB‐transcriptional targets as diagnostic markers. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

TROP-2, Nectin-4, GPNMB, and B7-H3 Are Potentially Therapeutic Targets for Anaplastic Thyroid Carcinoma.

Simple SummaryAnaplastic thyroid carcinoma is a highly aggressive thyroid tumor with a poor prognosis. There are limited choices for the effective treatment of this type of carcinoma. Whether the targets of antibody–drug conjugates are expressed in anaplastic thyroid carcinoma remains unclear. Therefore, we examined expression rates of the following antibody–drug conjugate targets using the tissue microarrays of anaplastic thyroid carcinomas: human epidermal growth factor receptor 2, nectin-4, trophoblast cell surface antigen 2, glycoprotein non-metastatic B, and B7-H3. We found that glycoprotein non-metastatic B and B7-H3 were expressed in most anaplastic thyroid carcinoma tissues. Trophoblast cell surface antigen 2 and nectin-4 were expressed in 65% and 59% of anaplastic thyroid carcinoma tissues, respectively. Trophoblast cell surface antigen 2 was high expressed in anaplastic thyroid carcinoma undifferentiated from papillary thyroid carcinoma. In contrast, nectin-4 expression was high in patients with de novo anaplastic thyroid carcinoma. These cell membrane proteins are potential therapeutic targets for anaplastic thyroid carcinoma.Background: Anaplastic thyroid carcinoma (ATC) is a highly aggressive thyroid tumor with a poor prognosis. However, there are limited choices for ATC treatment. Recently, the effectiveness of antibody–drug conjugates has been demonstrated in various carcinomas. Whether the targets of antibody–drug conjugates are expressed in anaplastic thyroid carcinoma remains unclear. Methods: Fifty-four patients with ATC were enrolled in this study. Tissue microarrays were constructed using the archives of formalin-fixed paraffin-embedded tissue blocks. All sections were stained with the following antibody–drug conjugate targets: human epidermal growth factor receptor 2 (HER2), nectin-4, trophoblast cell surface antigen 2 (TROP-2), glycoprotein non-metastatic B (GPNMB), and B7-H3. Results: HER2 was negative in all tissues, whereas GPNMB and B7-H3 were expressed in most ATC tissues. TROP-2 and nectin-4 were expressed in 65% and 59% of ATC tissues, respectively. TROP-2 was expressed at significantly higher levels in ATC undifferentiated from papillary thyroid carcinoma than in ATC undifferentiated from follicular thyroid carcinoma and de novo ATC. In contrast, nectin-4 expression was markedly higher in patients with de novo ATC than in those with papillary and follicular thyroid carcinoma. Conclusions: TROP-2 and nectin-4 are potential therapeutic targets for ATC undifferentiated from papillary thyroid carcinoma and de novo ATC, respectively. GPNMB and B7-H3 potential for treating all types of ATC.

Expression pattern and prognostic impact of glycoprotein non-metastatic B (GPNMB) in triple-negative breast cancer

Glycoprotein non-metastatic B (GPNMB) is a transmembrane protein overexpressed in numerous cancers including triple-negative breast cancers (TNBC). It has been linked to promote cancer aggressiveness and implicated as a novel target for GPNMB-expressing cancers. In current study, we aimed to explore the clinical significance of GPNMB in TNBC. Among 759 specimens, immunohistochemistry (IHC) exhibited GPNMB expressions were variable in different subtypes and significantly higher in TNBC. Kaplan–Meier analysis revealed GPNMB overexpression in TNBC was associated with worse prognosis especially distant metastasis (P = 0.020, HR = 2.515, CI 1.154–5.480). Multivariate analysis showed GPNMB expression was an independent prognostic factor in terms of recurrence and distant metastasis (P = 0.008, HR = 3.22, CI 1.36–7.61; P = 0.017, HR = 3.08, CI 1.22–7.74). In silico analysis showed high mRNA expression of GPNMB was associated with distant metastasis and GPNMB was overexpressed in TNBC. Furthermore, GPNMB positively correlated with epithelial–mesenchymal transition (EMT) regulators, mesenchymal marker vimentin, MMP and integrins. The protein levels of Twist and MMP2 were upregulated by GPNMB overexpression in TNBC cells. GPNMB-enhanced cell invasion was attenuated by broad spectrum MMP inhibitor (GM 6001) and the selective inhibitor of MMP-2 (ARP100). In summary, GPNMB expression is prevalent in TNBC and may be implicated as a prognostic biomarker in patients with TNBC.

549 Disappearance of keratinocyte expression of Glycoprotein Non-metastatic B (GPNMB) / Osteoactivin in vitiligo – possible involvement of Th1/Th 17 cytokines

GPNMB is a highly glycosylated type I transmembrane protein, which is known to be expressed in many cell types with multiple functions including cell adhesion, stress protection, and stem cell maintenance. In the skin, melanocyte GPNMB is suggested to mediate pigmentation through melanosome formation, but details of its expression and function in epidermal keratinocytes are not well characterized. We previously confirmed the predominant expression of GPNMB at a lower calcium condition in cultured normal human epidermal keratinocytes (NHEK). Histological staining showed that GPNMB was expressed in the basal layer of normal skins, but disappeared completely in vitiligo. To consider the reason for the loss of epidermal GPNMB in vitiligo, we examined the effects of candidate cytokines and chemokines in vitiligo development on GPNMB expression as well as on the formation of soluble GPNMB (sGPNMB). We demonstrated that IFN-γ downregulated keratinocyte GPNMB following JAK2/STAT1 signaling axis. IL-17A also inhibited its expression, whereas CXCL10, CXCL12 and CXCL16 showed no effect. NHEK secreted sGPNMB accounting about 4-5% of the total GPNMB. ADAM 10-selective inhibitor GI254023X decreased the sGPNMB production at the same extent as BB-94 with broad spectrum, suggesting the involvement of ADAM 10 in shedding GPNMB. Neither IFN-γ nor IL-17A was involved in this shedding process. These findings suggest that keratinocyte GPNMB could be a new target in vitiligo although further investigation on the roles of keratinocyte GPNMB to maintain functional melanocytes is needed.

A Human Organotypic Microfluidic Tumor Model Permits Investigation of the Interplay between Patient-Derived Fibroblasts and Breast Cancer Cells.

Tumor-stroma interactions significantly influence cancer cell metastasis and disease progression. These interactions are partly comprised of the cross-talk between tumor and stromal fibroblasts, but the key molecular mechanisms within the cross-talk that govern cancer invasion are still unclear. Here, we adapted our previously developed microfluidic device as a 3D in vitro organotypic model to mechanistically study tumor-stroma interactions by mimicking the spatial organization of the tumor microenvironment on a chip. We cocultured breast cancer and patient-derived fibroblast cells in 3D tumor and stroma regions, respectively, and combined functional assessments, including cancer cell migration, with transcriptome profiling to unveil the molecular influence of tumor-stroma cross-talk on invasion. This led to the observation that cancer-associated fibroblasts (CAF) enhanced invasion in 3D by inducing expression of a novel gene of interest, glycoprotein nonmetastatic B (GPNMB), in breast cancer cells, resulting in increased migration speed. Importantly, knockdown of GPNMB blunted the influence of CAF on enhanced cancer invasion. Overall, these results demonstrate the ability of our model to recapitulate patient-specific tumor microenvironments to investigate the cellular and molecular consequences of tumor-stroma interactions. SIGNIFICANCE: An organotypic model of tumor-stroma interactions on a microfluidic chip reveals that CAFs promote invasion by enhancing expression of GPNMB in breast cancer cells.

111In-Labeled Glycoprotein Nonmetastatic b (GPNMB) Targeted Gemini Surfactant-Based Nanoparticles against Melanoma: In Vitro Characterization and in Vivo Evaluation in Melanoma Mouse Xenograft Model.

Melanoma is a devastating form of skin cancer with high tendency to metastasis. This work addresses the development of new targeted nanoparticles that can be used for single-photon emission computed tomography (SPECT) imaging of melanoma. Melanoma-specific glycoprotein nonmetastatic b (GPNMB) antigen targeted and nontargeted gemini nanoparticles were prepared, characterized, and radiolabeled with 111In. 111In-labeled nanoparticles were composed of gemini surfactant grafted with monoclonal antibody Fab fragment that targeted GPNMB. Specific uptake of GPNMB-Fab was studied in six melanoma cell lines using flow cytometry. In vitro cellular uptake and internalization were studied using flow cytometry, confocal laser scanning microscopy, and radiometric techniques. Specific uptake of anti-GPNMB targeted nanoparticles was observed in GPNMB expressing cells, which was higher than low expressing or control cells. In vitro studies showed that conjugation of GPNMB targeted nanoparticles led to enhanced intracellular uptake of the nanodelivery system, which is critical for drug delivery. In vivo distribution of the nanoparticles was studied by microSPECT/CT imaging and ex vivo biodistribution. Tumor uptake was significantly higher ( p < 0.05) in nontargeted nanoparticles (5.47 ± 0.46%IA/cc) compared to GPNMB targeted nanoparticles (1.87 ± 0.27% ID/cc), which might be attributed to the high spleen uptake of the targeted formulation. These findings demonstrated that the radiolabeled gemini nanoparticles are promising for image-guided radiotherapy of melanoma. Formulation optimization is needed to improved tumor uptake and in vivo intracellular delivery for radiotherapeutic applications.

Clinical Significance of Glycoprotein Non-metastatic B and Its Association with EGFR/HER2 in Gastrointestinal Cancer.

Glycoprotein non-metastatic B (GPNMB), a type I transmembrane glycoprotein, is overexpressed in melanoma and breast cancer and promotes cancer-cell invasion and motility. We previously reported cross-talk between GPNMB and human epidermal growth factor receptor 2 (HER2) in breast cancer, suggesting that GPNMB might play an important role in resistance to anti-HER2 therapy in breast cancer. Here, we clarified the association between GPNMB and HER-family proteins in gastrointestinal cancer by examining their relationships using gastric and colorectal cancer cell lines. We found that GPNMB depletion of by small-interfering RNA increased epidermal growth factor receptor (EGFR) expression and phosphorylation through AKT8 virus oncogene cellular homolog (AKT) and mitogen-activated protein kinase (MAPK) pathways. Additionally, treatment with cetuximab (CTX) also increased GPNMB expression, and combination therapy consisting of GPNMB depletion and CTX treatment significantly suppressed cell growth in colorectal cancer cell lines, but not in gastric cancer cell lines. Furthermore, we also evaluated changes in GPNMB expression in vivo, with immunohistochemistry detecting GPNMB overexpression in a colorectal cancer patient following anti-EGFR therapy. These results suggested possible cross-talk between GPNMB and EGFR, and that GPNMB might play an important role in resistance to anti-EGFR therapy in gastrointestinal cancer.

The laminin-derived peptide C16 regulates GPNMB expression and function in breast cancer

Breast cancer is an important public health problem, and its progression may be related to the extracellular matrix (ECM), which acts as a structural scaffold and instruction source for neoplastic cells. Laminins are ECM proteins regulating tumor biology. The laminin-derived peptide C16 regulates different properties of tumor cells. Here we analyzed C16-induced differential gene expression in MDA-MB-231 breast cancer cells. MCF-10A normal-like breast cells served as control. Among different cancer-related genes, C16 induced overexpression of GPNMB. This gene encodes a transmembrane protein GPNMB (glycoprotein non-metastatic B), involved with malignant phenotype of breast cancer cells. Immunoblot validated microarray results. To correlate gene and protein expression with cellular function, we investigated whether C16 would regulate invasion in breast cancer cells. siRNA experiments strongly suggested that C16 and GPNMB cooperate to regulate invasion of highly aggressive MDA-MB-231 cancer cells. We addressed regulatory mechanisms involved in C16-mediated increase of GPNMB protein levels in MDA-MB-231 cells, and observed that C16 stimulates β1 integrin and Src phosphorylation. Furthermore, Src inhibition decreases peptide-induced GPNMB expression levels. To contextualize in vivo our results in vitro, we addressed GPNMB immunostaining in breast cancer human tissue microarrays. Quantitative immunohistochemistry showed that GPNMB is significantly more expressed in breast cancer compared to normal tissue. We concluded that laminin-derived peptide C16 regulates gene and protein expression of GPNMB in breast cancer cells. C16 and GPNMB may cooperate to regulate invasion of highly aggressive MDA-MB-231 cells, probably through Src signaling. GPNMB presented increased expression in breast cancer in vivo compared to normal breast tissue.

Abstract P5-04-03: Targeting glycoprotein non-metastatic B (GPNMB) to overcome EGFR-mediated resistance to Mek inhibition in triple negative breast cancer

Abstract Background: Triple negative breast cancer (TNBC) is an aggressive subtype that constitutes ∼15% of all BC. Currently there are no targeted therapies available for patients with TNBC and these patients have a poor prognosis. As such, there is much interest in developing targeted therapies for this disease. Recently we identified GPNMB as a transmembrane protein that promotes breast tumor growth and metastasis. CDX-011 is an antibody drug conjugate that targets GPNMB, and has recently shown promising clinical activity in patients with GPNMB+TNBC. In subset analyses of the EMERGE trial, patients with high GPNMB expressing TNBC had a median OS of 10 vs. 5.5 months for CDX011 versus chemotherapy, respectively. Response rates to CDX011 correlated with degree of GPNMB expression. These findings support the hypothesis that TNBC with high GPNMB will respond better to CDX011. As such, we sought to identify therapies with intrinsic activity against TNBC that would also induce GPNMB expression, in order to synergize with CDX-011. Recently there has been much interest in targeting the MAPK pathway in TNBC. We have recently shown that MAPK pathway inhibition induces GPNMB expression in melanoma. Therefore we sought to determine whether mek inhibition induced GPNMB in TNBC and the targeted therapies could synergize with CDX-011. Results: We interrogated the TCGA breast dataset to determine whether the MAPK pathway is more frequently altered in TNBC. Indeed, we find that the MAPK pathway is altered in 93% of basal BC compared to 56%, 82%, and 81% of Lum A, LumB, and Her2 subtypes, respectively. We used immunoblot and FACS analysis to assess GPNMB expression in response to MAPK-inhibition. We found that mek inhibitors (trametinib, cobimetinib) markedly induced GPNMB protein expression in several TNBC cell lines. RTK upregulation has been proposed as an adaptive resistance mechanism to mek inhibition in TNBC. Indeed, we find that EGFR is upregulated in response to Mek inhibition in MDA-MB-468 and Hs578T cells. Using shRNA to knockdown GPNMB expression in MDA-MB-468 cells or ectopic GPNMB overexpression in Hs578t cells, we found that GPNMB is both necessary and sufficient for enhanced EGFR activation in response to Mek inhibition in TNBC. Interestingly, we also find that Hs578T cells overexpressing GPNMB show less growth inhibition in response to Mek inhibitors compared to control cells in vitro. These in vitro data are corroborated by our analyses of 1097 breast tumors from the TCGA dataset. GPNMB alterations were found in 7% of all BC and correlates significantly with increased EGFR, Mek and Erk activation. Finally, we are investigating the efficacy of combining trametinib with CDX011 to treat TNBC using in vivo mouse models. Preliminary data from this experiment suggest that MDA-MB-468 tumors treated with both drugs are more growth restricted than tumors treated with either drug alone. Final data will be presented at the meeting. Conclusions: Mek inhibition induces GPNMB expression in TNBC. GPNMB promotes EGFR activation and protects from mek-inhibitor induced growth inhibition. The combination of a mek inhibitor with CDX011 shows promise in pre-clinical models and warrants further investigation in clinical trials. Citation Format: Rose AA, Annis MG, Maric G, Siegel PM. Targeting glycoprotein non-metastatic B (GPNMB) to overcome EGFR-mediated resistance to Mek inhibition in triple negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-04-03.

Targeting Glycoprotein NMB With Antibody-Drug Conjugate, Glembatumumab Vedotin, for the Treatment of Osteosarcoma.

Cure rates for children and young adults with osteosarcoma have remained stagnant over the past three decades. Targeting glycoprotein non-metastatic b (GPNMB) with the antibody-drug conjugate glembatumumab vedotin has improved outcomes for patients with melanoma and breast cancer. The potential utility of targeting GPNMB in osteosarcoma was explored. GPNMB protein expression was evaluated by immunohistochemistry in human osteosarcoma tumor samples and by enzyme-linked immunosorbent assay (ELISA) in osteosarcoma cell lines. mRNA expression was measured by quantitative PCR in primary osteosarcoma samples and cell lines. Surface GPNMB expression was evaluated by flow cytometry and correlated with in vitro and in vivo cytotoxicity of glembatumumab vedotin. Sixty seven human osteosarcoma samples were evaluated by immunohistochemistry, including 12 samples from initial biopsy, 38 samples from definitive surgery, and 17 from the time of disease recurrence. GPNMB was expressed in 92.5% (62/67) of osteosarcoma samples. All primary osteosarcoma samples expressed high levels of GPNMB mRNA. Glembatumumab induced cytotoxic effects in 74% (14/19) of osteosarcoma cell lines, and GPNMB protein levels correlated with glembatumumab in vitro cytotoxicity (r = -0.46, P = 0.04). All osteosarcoma cell lines demonstrated surface GPNMB expression. GPNMB is expressed in osteosarcoma and targeting GPNMB with the antibody-drug conjugate glembatumumab vedotin demonstrates osteosarcoma cytotoxic activity. Clinical trials are indicated to assess the efficacy of targeting GPNMB in patients with osteosarcoma.

Clinical significance of glycoprotein nonmetastatic B and its association with HER2 in breast cancer.

Glycoprotein nonmetastatic B (GPNMB) is a potential oncogene that is particularly expressed in melanoma and breast cancer (BC). To clarify its clinical significance in BC, we measured serum GPNMB in vivo and investigated its cross talk with human epidermal growth factor 2 (HER2). GPNMB was expressed in four of six breast cell lines (SK-BR-3, BT-474, MDA-MD-231, and MDA-MD-157), two of six colorectal cell lines, and two of four gastric cancer (GC) cell lines. We established a GPNMB quantification system using enzyme-linked immunosorbent assay (ELISA) for these cell lines. We measured serum GPNMB in vivo in 162 consecutive BC patients and in 88 controls (50 colorectal cancer [CC] and 38 GC patients). The GPNMB concentration in BC, CC and GC was 8.163, 5.751 and 6.55 ng/mL, respectively. The GPNMB level was significantly higher in BC patients than in CC patients (P = 0.021). The HER2-rich subtype of BC patients had significantly higher GPNMB levels than other subtypes (vs. Luminal; P = 0.038; vs. DCIS; P = 0.0195). These high GPNMB levels decreased after treatment (surgery/chemotherapy). Next, we examined the relationship between GPNMB and HER2 in vitro using SK-BR3 and BT-474 (HER2-positive/GPNMB-positive) cells. GPNMB depletion by small interfering RNA (siRNA) increased both HER2 expression and phosphorylation. Trastuzumab (Tra) in combination with docetaxel promoted cell growth inhibition, and treatment with Tra or an Extracellular signal-related kinase (ERK) inhibitor enhanced GPNMB expression. These results indicate that GPNMB might be a surrogate marker for BC and may cross talk with the HER2 signal pathway. GPNMB may therefore emerge as an important player in anti-HER2 therapy.

Identification of a Biomarker in Cerebrospinal Fluid for Neuronopathic Forms of Gaucher Disease

Gaucher disease, a recessive inherited metabolic disorder caused by defects in the gene encoding glucosylceramidase (GlcCerase), can be divided into three subtypes according to the appearance of symptoms associated with central nervous system involvement. We now identify a protein, glycoprotein non-metastatic B (GPNMB), that acts as an authentic marker of brain pathology in neurological forms of Gaucher disease. Using three independent techniques, including quantitative global proteomic analysis of cerebrospinal fluid (CSF) in samples from Gaucher disease patients that display neurological symptoms, we demonstrate a correlation between the severity of symptoms and GPNMB levels. Moreover, GPNMB levels in the CSF correlate with disease severity in a mouse model of Gaucher disease. GPNMB was also elevated in brain samples from patients with type 2 and 3 Gaucher disease. Our data suggest that GPNMB can be used as a marker to quantify neuropathology in Gaucher disease patients and as a marker of treatment efficacy once suitable treatments towards the neurological symptoms of Gaucher disease become available.