FN14 and GRP94 expression are prognostic/predictive biomarkers of brain metastasis outcome that open up new therapeutic strategies

Nerve growth factor inducible (VGF) is a secreted mediator for metastatic breast cancer tropism to the brain

Brain metastases are one of the most serious clinical problems in breast cancer (BC) progression, associated with lower survival rates and a lack of effective therapies. Thus, to dissect the early stages of the brain metastatic process, we studied the impact of brain organotropic BC cells' secretomes on the establishment of the brain pre-metastatic niche (PMN). We found that BC cells with specific tropism to the brain caused significant blood-brain barrier (BBB) disruption, as well as microglial activation, in both in vitro and in vivo models. Further, we searched for a brain-organotropic metastatic signature, as a promising source for the discovery of new biomarkers involved in brain metastatic progression. Of relevance, we identified VGF (nerve growth factor inducible) as a key mediator in this process, also impacting the BBB and microglial functions both in vitro and in vivo. In a series of human breast tumors, VGF was found to be expressed in both cancer cells and the adjacent stroma. Importantly, VGF-positive tumors showed a significantly worse prognosis and were associated with HER2 (human epidermal growth factor receptor 2) overexpression and triple-negative molecular signatures. Further clinical validation in primary tumors from metastatic BC cases showed a significant association between VGF and the brain metastatic location, clearly and significantly impacting on the prognosis of BC patients with brain metastasis. In conclusion, our study reveals a unique secretome signature for BC with a tropism for the brain, highlighting VGF as a crucial mediator in this process. Furthermore, its specific impact as a poor prognostic predictor for BC patients with brain metastasis opens new avenues to target VGF to control the progression of brain metastatic disease. © 2024 The Pathological Society of Great Britain and Ireland.

RANK is a poor prognosis marker and a therapeutic target in ER-negative postmenopausal breast cancer

Despite strong preclinical data, the therapeutic benefit of the RANKL inhibitor, denosumab, in breast cancer patients, beyond the bone, is unclear. Aiming to select patients who may benefit from denosumab, we hereby analyzed RANK and RANKL protein expression in more than 2,000 breast tumors (777 estrogen receptor-negative, ER- ) from four independent cohorts. RANK protein expression was more frequent in ER- tumors, where it associated with poor outcome and poor response to chemotherapy. In ER- breast cancer patient-derived orthoxenografts (PDXs), RANKL inhibition reduced tumor cell proliferation and stemness, regulated tumor immunity and metabolism, and improved response to chemotherapy. Intriguingly, tumor RANK protein expression associated with poor prognosis in postmenopausal breast cancer patients, activation of NFKB signaling, and modulation of immune and metabolic pathways, suggesting that RANK signaling increases after menopause. Our results demonstrate that RANK protein expression is an independent biomarker of poor prognosis in postmenopausal and ER- breast cancer patients and support the therapeutic benefit of RANK pathway inhibitors, such as denosumab, in breast cancer patients with RANK+ ER- tumors after menopause.

Molecular aspects of brain metastases in breast cancer

Brain metastases (BM) are a common and devastating manifestation of breast cancer (BC). BM are particularly frequent in the HER2-positive and triple-negative breast cancer phenotypes and usually occur following the metastatic spread to extracranial sites. Several genes mediating BM and biomarkers predicting their risk in BC have been reported in the past decade. These findings have advanced the understanding of BM pathobiology and paved the way for developing new therapeutic strategies but they still warrant a thorough clinical validation. Hence, a better understanding of the mechanistic aspects of BM and delineating the interactions of tumor cells with the brain microenvironment are of utmost importance. This review discusses the molecular basis of the metastatic cascade: the epithelial-mesenchymal transition, cancer, and tumor microenvironment interaction and intravasation, priming of the metastatic niche in the brain, and survival in the new site. We also outline the postulated mechanisms of BC cells' brain tropism. Finally, we discuss advances in the field of biomarkers (both tissue-based and liquid-based) that predict BM from BC.

The biology and inhibition of glucose-regulated protein 94/gp96

The 94 kDa molecular chaperone, glucose-regulated protein 94 (Grp94), has garnered interest during the last decade due to its direct association with endoplasmic reticulum (ER) stress and disease. Grp94 belongs to the Hsp90 family of molecular chaperones and is a master regulator of ER homeostasis due to its ability to fold and stabilize proteins/receptors, and to chaperone misfolded proteins for degradation. Multiple studies have demonstrated that Grp94 knockdown or inhibition leads to the degradation of client protein substrates, which leads to disruption of disease-dependent signaling pathways. As a result, small molecule inhibitors of Grp94 have become a promising therapeutic approach to target a variety of disease states. Specifically, Grp94 has proven to be a promising target for cancer, glaucoma, immune-mediated inflammation, and viral infection. Moreover, Grp94-peptide complexes have been utilized effectively as adjuvants for vaccines against a variety of disease states. This work highlights the significance of Grp94 biology and the development of therapeutics that target this molecular chaperone in multiple disease states.

Targeting fibroblast growth factor (FGF)-inducible 14 (Fn14) for tumor therapy

Fibroblast growth factor-inducible 14 (Fn14) is a member of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF) and is activated by its ligand TNF-like weak inducer of apoptosis (TWEAK). The latter occurs as a homotrimeric molecule in a soluble and a membrane-bound form. Soluble TWEAK (sTWEAK) activates the weakly inflammatory alternative NF-κB pathway and sensitizes for TNF-induced cell death while membrane TWEAK (memTWEAK) triggers additionally robust activation of the classical NF-κB pathway and various MAP kinase cascades. Fn14 expression is limited in adult organisms but becomes strongly induced in non-hematopoietic cells by a variety of growth factors, cytokines and physical stressors (e.g., hypoxia, irradiation). Since all these Fn14-inducing factors are frequently also present in the tumor microenvironment, Fn14 is regularly found to be expressed by non-hematopoietic cells of the tumor microenvironment and most solid tumor cells. In general, there are three possibilities how the tumor-Fn14 linkage could be taken into consideration for tumor therapy. First, by exploitation of the cancer associated expression of Fn14 to direct cytotoxic activities (antibody-dependent cell-mediated cytotoxicity (ADCC), cytotoxic payloads, CAR T-cells) to the tumor, second by blockade of potential protumoral activities of the TWEAK/Fn14 system, and third, by stimulation of Fn14 which not only triggers proinflammtory activities but also sensitizes cells for apoptotic and necroptotic cell death. Based on a brief description of the biology of the TWEAK/Fn14 system and Fn14 signaling, we discuss the features of the most relevant Fn14-targeting biologicals and review the preclinical data obtained with these reagents. In particular, we address problems and limitations which became evident in the preclinical studies with Fn14-targeting biologicals and debate possibilities how they could be overcome.

Pan-cancer analysis of the prevalence and associated factors of lung metastasis and the construction of the lung metastatic classification system

This study first presents an analysis of the prevalence and associated factors of the lung metastasis (LM) database and then uses this analysis to construct an LM classification system. Using cancer patient data gathered from the surveillance, epidemiology, and end results (SEER) database, this study shows that the prevalence of LM is not consistent among different cancers; that is, the prevalence of LM ranges from 0.0013 [brain; 95% confidence interval (95% CI); 0.0010–0.0018] to 0.234 (“other digestive organs”; 95% CI; 0.221–0.249). This study finds that advanced age, poor grade, higher tumor or node stage, and metastases including bone, brain, and liver are positively related to LM occurrence, while female gender, income, marital status, and insured status are negatively related. Then, this study generates four categories from 58 cancer types based on prevalence and influence factors and satisfactorily validates these. This classification system reflects the LM risk of different cancers. It can guide individualized treatment and the management of these synchronous metastatic cancer patients and help clinicians better distribute medical resources.

GRP94 promotes brain metastasis by engaging pro-survival autophagy

BACKGROUND

GRP94 is a glucose-regulated protein critical for survival in endoplasmic reticulum stress. Expression of GRP94 is associated with cellular transformation and increased tumorigenicity in breast cancer. Specifically, overexpression of GRP94 predicts brain metastasis (BM) in breast carcinoma patients with either triple negative or ErbB2 positive tumors. The aim of this study was to understand if microenvironmental regulation of GRP94 expression might be a hinge orchestrating BM progression.

METHODS

GRP94 ablation was performed in a BM model BR-eGFP-CMV/Luc-V5CA1 (BRV5CA1) of breast cancer. In vitro results were validated in a dataset of 29 metastases in diverse organs from human breast carcinomas and in BM tissue from tumors of different primary origin. BM patient-derived xenografts (PDXs) were used to test sensitivity to the therapeutic approach.

RESULTS

BMs that overexpress GRP94 as well as tumor necrosis factor receptor-associated factor 2 are more resistant to glucose deprivation by induction of anti-apoptotic proteins (B-cell lymphoma 2 and inhibitors of apoptosis proteins) and engagement of pro-survival autophagy. GRP94 ablation downregulated autophagy in tumor cells, resulting in increased BM survival in vivo. These results were validated in a metastasis dataset from human patients, suggesting that targeting autophagy might be strategic for BM prevention. Indeed, hydroxychloroquine treatment of preclinical models of BM from PDX exerts preventive inhibition of tumor growth (P < 0.001).

CONCLUSIONS

We show that GRP94 is directly implicated in BM establishment by activating pro-survival autophagy. Disruption of this compensatory fueling route might prevent metastatic growth.

Molecular Chaperone GRP94/GP96 in Cancers: Oncogenesis and Therapeutic Target

During tumor development and progression, intrinsic and extrinsic factors trigger endoplasmic reticulum (ER) stress and the unfolded protein response, resulting in the increased expression of molecular chaperones to cope with the stress and maintain tumor cell survival. Heat shock protein (HSP) GRP94, also known as GP96, is an ER paralog of HSP90 and has been shown to promote survival signaling during tumor-induced stress and modulate the immune response through its multiple clients, including TLRs, integrins, LRP6, GARP, IGF, and HER2. Clinically, elevated expression of GRP94 correlates with an aggressive phenotype and poor clinical outcome in a variety of cancers. Thus, GRP94 is a potential molecular marker and therapeutic target in malignancies. In this review, we will undergo deep molecular profiling of GRP94 in tumor development and summarize the individual roles of GRP94 in common cancers, including breast cancer, colon cancer, lung cancer, liver cancer, multiple myeloma, and others. Finally, we will briefly review the therapeutic potential of selectively targeting GRP94 for the treatment of cancers.

Evaluation of Computationally Designed Peptides against TWEAK, a Cytokine of the Tumour Necrosis Factor Ligand Family

The tumour necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the tumour necrosis factor ligand family and has been shown to be overexpressed in tumoral cells together with the fibroblast growth factor–inducible 14 (Fn14) receptor. TWEAK-Fn14 interaction triggers a set of intracellular pathways responsible for tumour cell invasion and migration, as well as proliferation and angiogenesis. Hence, modulation of the TWEAK-Fn14 interaction is an important therapeutic goal. The targeting of protein-protein interactions by external agents, e.g., drugs, remains a substantial challenge. Given their intrinsic features, as well as recent advances that improve their pharmacological profiles, peptides have arisen as promising agents in this regard. Here, we report, by in silico structural design validated by cell-based and in vitro assays, the discovery of four peptides able to target TWEAK. Our results show that, when added to TWEAK-dependent cellular cultures, peptides cause a down-regulation of genes that are part of TWEAK-Fn14 signalling pathway. The direct, physical interaction between the peptides and TWEAK was further elucidated in an in vitro assay which confirmed that the bioactivity shown in cell-based assays was due to the targeting of TWEAK. The results presented here are framed within early pre-clinical drug development and therefore these peptide hits represent a starting point for the development of novel therapeutic agents. Our approach exemplifies the powerful combination of in silico and experimental efforts to quickly identify peptides with desirable traits.

Brain Metastasis Cell Lines Panel: A Public Resource of Organotropic Cell Lines

Spread of cancer to the brain remains an unmet clinical need in spite of the increasing number of cases among patients with lung, breast cancer, and melanoma most notably. Although research on brain metastasis was considered a minor aspect in the past due to its untreatable nature and invariable lethality, nowadays, limited but encouraging examples have questioned this statement, making it more attractive for basic and clinical researchers. Evidences of its own biological identity (i.e., specific microenvironment) and particular therapeutic requirements (i.e., presence of blood-brain barrier, blood-tumor barrier, molecular differences with the primary tumor) are thought to be critical aspects that must be functionally exploited using preclinical models. We present the coordinated effort of 19 laboratories to compile comprehensive information related to brain metastasis experimental models. Each laboratory has provided details on the cancer cell lines they have generated or characterized as being capable of forming metastatic colonies in the brain, as well as principle methodologies of brain metastasis research. The Brain Metastasis Cell Lines Panel (BrMPanel) represents the first of its class and includes information about the cell line, how tropism to the brain was established, and the behavior of each model in vivo. These and other aspects described are intended to assist investigators in choosing the most suitable cell line for research on brain metastasis. The main goal of this effort is to facilitate research on this unmet clinical need, to improve models through a collaborative environment, and to promote the exchange of information on these valuable resources.

Application of chemometric methods to the analysis of multimodal chemical images of biological tissues

Current histology techniques, such as tissue staining or histochemistry protocols, provide very limited chemical information about the tissues. Chemical imaging technologies such as infrared, Raman, and mass spectrometry imaging, are powerful analytical techniques with a huge potential in describing the chemical composition of sample surfaces. In this work, three images of the same tissue slice using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, infrared microspectroscopy, and an RGB picture from a conventional hematoxylin/eosin (H/E) staining are simultaneously analyzed. These fused images were analyzed by multivariate curve resolution-alternating least squares (MCR-ALS), which provided, for each component, its distribution within the tissue surface, its IR spectrum fingerprint, its characteristic mass values, and the contribution of the RGB channels of the H/E staining. Compared with the individual analysis of each of the images alone, the fusion of the three images showed the relationship between the different types of chemical/biological information and enabled a better interpretation of the tissue under study. In addition, the least-squares projection of the MCR-ALS resolved spectra of components at low spatial resolution onto the IR and RBG images at high spatial resolution, provided a better delimitation of the sample constituents on the image, giving a more precise description of their distribution on the investigated tissue. The application of this procedure can be of interest in different research areas in which a good description of the spatial distribution of the chemical constituents of the samples is needed, such as in biomedicine, food, or environmental research.

Bisubstrate-Type Chemical Probes Identify GRP94 as a Potential Target of Cytosine-Containing Adenosine Analogs

We synthesized affinity-based chemical probes of cytosine-adenosine bisubstrate analogs and identified several potential targets by proteomic analysis. The validation of the proteomic analysis identified the chemical probe as a specific inhibitor of glucose-regulated protein 94 (GRP94), a potential drug target for several types of cancers. Therefore, as a result of the use of bisubstrate-type chemical probes and a chemical-biology methodology, this work opens the way to the development of a new family of GRP94 inhibitors that could potentially be of therapeutic interest.

Risk factors for breast cancer brain metastases: a systematic review

Background: Brain metastasis (BM) is an increasingly common and devastating complication of breast cancer (BC).

Methods: A systematic literature search of EMBASE and MEDLINE was conducted to elucidate the current state of knowledge on known and novel prognostic factors associated with 1) the risk for BCBM and 2) the time to brain metastases (TTBM).

Results: A total of 96 studies involving institutional records from 28 countries were identified. Of these, 69 studies reported risk factors of BCBM, 46 factors associated with the TTBM and twenty studies examined variables for both outcomes. Young age, estrogen receptor negativity (ER-), overexpression of human epidermal factor (HER2+), and higher presenting stage, histological grade, tumor size, Ki67 labeling index and nodal involvement were consistently found to be independent risk factors of BCBM. Of these, triple-negative BC (TNBC) subtype, ER-, higher presenting histological grade, tumor size, and nodal involvement were also reported to associate with shorter TTBM. In contrast, young age, hormone receptor negative (HR-) status, higher presenting stage, nodal involvement and development of liver metastasis were the most important risk factors for BM in HER2-positive patients.

Conclusions: The study provides a comprehensive and individual evaluation of the risk factors that could support the design of screening tools and interventional trials for early detection of BCBM.

GRP94 Is Involved in the Lipid Phenotype of Brain Metastatic Cells

Metabolic adaptation may happen in response to the pressure exerted by the microenvironment and is a key step in survival of metastatic cells. Brain metastasis occurs as a consequence of the systemic dissemination of tumor cells, a fact that correlates with poor prognosis and high morbidity due to the difficulty in identifying biomarkers that allow a more targeted therapy. Previously, we performed transcriptomic analysis of human breast cancer patient samples and evaluated the differential expression of genes in brain metastasis (BrM) compared to lung, bone and liver metastasis. Our network approach identified upregulation of glucose-regulated protein 94 (GRP94) as well as proteins related to synthesis of fatty acids (FA) in BrM. Here we report that BrM cells show an increase in FA content and decreased saturation with regard to parental cells measured by Raman spectroscopy that differentiate BrM from other metastases. Moreover, BrM cells exerted a high ability to oxidize FA and compensate hypoglycemic stress due to an overexpression of proteins involved in FA synthesis and degradation (SREBP-1, LXRα, ACOT7). GRP94 ablation restored glucose dependence, down-regulated ACOT7 and SREBP-1 and decreased tumorigenicity in vivo. In conclusion, GRP94 is required for the metabolic stress survival of BrM cells, and it might act as a modulator of lipid metabolism to favor BrM progression.

Co-downregulation of GRP78 and GRP94 Induces Apoptosis and Inhibits Migration in Prostate Cancer Cells

Background

Both glucose-regulated protein 78 kDa (GRP78) and glucose-regulated protein 94 kDa (GRP94) are important molecular chaperones that play critical roles in maintaining tumor survival and progression. This study investigated the effects in prostate cancer cells following the downregulation of GRP78 and GRP94.

Methods

RNA interference was used to downregulate GRP78 and GRP94 expression in the prostate cancer cell line, PC-3. The effects on apoptosis and cell migration was examined along with expression of these related proteins.

Results

Small interfering RNAs targeting GRP78 and GRP94 successfully down-regulated their expression. This resulted in the induction of apoptosis and inhibition of cell migration. Preliminary mechanistic studies indicated that caspase-9 (cleaved) and Bax expression levels were upregulated while Bcl-2 and vimentin expression levels were downregulated.

Conclusion

Co-downregulation of GRP78 and GRP94 expression induces apoptosis and inhibits migration in prostate cancer cells.

Molecular and cellular stratagem of brain metastases associated with melanoma

Tumors of the central nervous system are the most prevalent complications of melanoma, especially in the late stage of disease. Melanoma, lung and breast cancer are the leading cause of secondary tumors in the brain, the majority of them having a poor outcome. Brain dissemination is developed in half of stage IV melanomas and these cases can increase up to 75%, having a major impact on the quality of life. This review will focus on recent findings that provide new ways to potentially prevent brain metastases in malignant melanoma. The key of these findings is based on the heterogeneity of the melanoma and of the brain metastases at genetic levels. This new era of technologies provides new tools in understanding the dissemination mechanisms of malignant cells. The cellular and molecular changes, the immune status of the patient and the blood-brain barrier permeability are key regulators of cancer cell dissemination. Understanding these mechanisms can render new hope in preventing brain metastases by focusing on melanoma and new pharmacologic approaches.

Glucose-Regulated Protein 94 Modulates the Response of Osteosarcoma to Chemotherapy

Background

Osteosarcoma (OS) is the most common and most aggressive primary solid malignant bone tumor in children and young adults and has high rates of recurrence and metastasis. The endoplasmic reticulum (ER) stress pathway is important in regulating the chemo-responsiveness of cancer. However, the role of glucose-regulated protein 94 (GRP94) in regulating the response of OS to chemotherapy has never been explored.

Methods

In this study, two OS cell lines, MG63 and 143B cells, were used to evaluate the mechanism by which GRP94 modulates the response of osteosarcoma to chemotherapy. GRP94-knockdown (GRP94-KD) OS cells were generated using short hairpin RNAs, and the response to chemotherapy was assessed using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cell apoptosis was quantified with propidium iodide (PI) staining and flow cytometry.

Results

Silencing of GRP94 in MG63 and 143B cells did not influence the growth and migration of the cells, but reduced the colony formation. GRP94-KD OS cells were more resistant to paclitaxel, gemcitabine, and epirubicin treatments than cells transfected with the scrambled control, and more cells transfected with the scrambled control underwent apoptosis after paclitaxel, gemcitabine, and epirubicin treatments than GRP94-KD cells.

Conclusions

Therefore, GRP94 silencing may increase the resistance of MG63 and 143B cells to paclitaxel, gemcitabine, and epirubicin treatments by inhibiting the induction of apoptosis. Thus, GRP94 may be a key biomarker for the chemotherapeutic response of OS.

Therapy of breast cancer brain metastases: challenges, emerging treatments and perspectives

Brain metastases are the most common central nervous system tumors in adults, and incidence of brain metastases is increasing due to both improved diagnostic techniques (e.g. magnetic resonance imaging) and increased cancer patient survival through advanced systemic treatments. Outcomes of patients remain disappointing and treatment options are limited, usually involving multimodality approaches. Brain metastases represent an unmet medical need in solid tumor care, especially in breast cancer, where brain metastases are frequent and result in impaired quality of life and death. Challenges in the management of brain metastases have been highlighted in this review. Innovative research and treatment strategies, including prevention approaches and emerging systemic treatment options for brain metastases of breast cancer, are further discussed.

Tnfrsf12a-Mediated Atherosclerosis Signaling and Inflammatory Response as a Common Protection Mechanism of Shuxuening Injection Against Both Myocardial and Cerebral Ischemia-Reperfusion Injuries

Shuxuening injection (SXNI) is a widely prescribed herbal medicine of Ginkgo biloba extract (EGB) for cerebral and cardiovascular diseases in China. However, its curative effects on ischemic stroke and heart diseases and the underlying mechanisms remain unknown. Taking an integrated approach of RNA-seq and network pharmacology analysis, we compared transcriptome profiles of brain and heart ischemia reperfusion injury in C57BL/6J mice to identify common and differential target genes by SXNI. Models for myocardial ischemia reperfusion injury (MIRI) by ligating left anterior descending coronary artery (LAD) for 30 min ischemia and 24 h reperfusion and cerebral ischemia reperfusion injury (CIRI) by middle cerebral artery occlusion (MCAO) for 90 min ischemia and 24 h reperfusion were employed to identify the common mechanisms of SXNI on both cerebral and myocardial ischemia reperfusion. In the CIRI model, ischemic infarct volume was markedly decreased after pre-treatment with SXNI at 0.5, 2.5, and 12.5 mL/kg. In the MIRI model, pre-treatment with SXNI at 2.5 and 12.5 mL/kg improved cardiac function and coronary blood flow and decreased myocardial infarction area. Besides, SXNI at 2.5 mL/kg also markedly reduced the levels of LDH, AST, CK-MB, and CK in serum. RNA-seq analysis identified 329 differentially expressed genes (DEGs) in brain and 94 DEGs in heart after SXNI treatment in CIRI or MIRI models, respectively. Core analysis by Ingenuity Pathway Analysis (IPA) revealed that atherosclerosis signaling and inflammatory response were top-ranked in the target profiles for both CIRI and MIRI after pre-treatment with SXNI. Specifically, Tnfrsf12a was recognized as an important common target, and was regulated by SXNI in CIRI and MIRI. In conclusion, our study showed that SXNI effectively protects brain and heart from I/R injuries via a common Tnfrsf12a-mediated pathway involving atherosclerosis signaling and inflammatory response. It provides a novel knowledge of active ingredients of Ginkgo biloba on cardio-cerebral vascular diseases in future clinical application.

The Evolving Landscape of Brain Metastasis

Metastasis, involving the spread of systemic cancer to the brain, results in neurologic disability and death. Current treatments are largely palliative in nature; improved therapeutic approaches represent an unmet clinical need. However, recent experimental and clinical advances challenge the bleak long-term outcome of this disease. Encompassing key recent findings in epidemiology, genetics, microenvironment, leptomeningeal disease, neurocognition, targeted therapy, immunotherapy, and prophylaxis, we review preclinical and clinical studies to provide a comprehensive picture of contemporary research and the management of secondary brain tumors.

Grp94 in complexes with IgG is a soluble diagnostic marker of gastrointestinal tumors and displays immune-stimulating activity on peripheral blood immune cells

Glucose-regulated protein94 (Grp94), the most represented endoplasmic reticulum (ER)-resident heat shock protein (HSP), is a tumor antigen shared by different types of solid and hematological tumors. The tumor-specific feature of Grp94 is its translocation from the ER to the cell surface where it displays pro-oncogenic functions. This un-physiological location has important implications for both the tumor pathology and anti-tumor therapy. We wanted to address the question of whether Grp94 could be measured as liquid marker in cancer patients in order to make predictions of diagnostic and therapeutic relevance for the tumor. To this aim, we performed an in-depth investigation on patients with primary tumors of the gastrointestinal (GI) tract, using different methodological approaches to detect Grp94 in tumor tissues, plasma and peripheral blood mononuclear cells (PBMCs). Results indicate that Grp94 is not only the antigen highly expressed in any tumor tissue and in cells of tumor infiltrates, mostly B lymphocytes, but it is also found in the circulation. However, the only form in which Grp94 was detected in the plasma of any patients and in B lymphocytes induced to proliferate, was that of stable complexes with Immunoglobulin (Ig)G. Using a specific immune-enzyme assay to measure plasma Grp94-IgG complexes, we showed that Grp94-IgG complexes were significantly increased in cancer patients compared to healthy control subjects, serving as diagnostic tumor biomarker. Results also demonstrate that the stimulation of patient PBMCs with Grp94-IgG complexes led to an increased secretion of inflammatory cytokines that might drive a potentially beneficial anti-tumor effect.

Reactive Astrocytes in Brain Metastasis

Brain metastasis, the secondary growth of malignant cells within the central nervous system (CNS), exceeds the incidence of primary brain tumors (i.e., gliomas) by tenfold and are seemingly on the rise owing to the emergence of novel targeted therapies that are more effective in controlling extracranial disease relatively to intracranial lesions. Despite the fact that metastasis to the brain poses a unmet clinical problem, with afflicted patients carrying significant morbidity and a fatal prognosis, our knowledge as to how metastatic cells manage to adapt to the tissue environment of the CNS remains limited. Answering this question could pave the way for novel and more specific therapeutic modalities in brain metastasis by targeting the specific makeup of the brain metastatic niche. In regard to this, astrocytes have emerged as the major host cell type that cancer cells encounter and interact with during brain metastasis formation. Similarly to other CNS disorders, astrocytes become reactive and respond to the presence of cancer cells by changing their phenotype and significantly influencing the outcome of disseminated cancer cells within the CNS. Here, we summarize the current knowledge on the contribution of reactive astrocytes in brain metastasis by focusing on the signaling pathways and types of interactions that play a crucial part in the communication with cancer cells and how these could be translated into innovative therapies.

Predictive and Prognostic Brain Metastases Assessment in Luminal Breast Cancer Patients: FN14 and GRP94 from Diagnosis to Prophylaxis

FN14 has been implicated in many intracellular signaling pathways, and GRP94 is a well-known endoplasmic reticulum protein regulated by glucose. Recently, both have been associated with metastasis progression in breast cancer patients. We studied the usefulness of FN14 and GRP94 expression to stratify breast cancer patients according their risk of brain metastasis (BrM) progression. We analyzed FN14 and GRP94 by immunohistochemistry in a retrospective multicenter study using tissue microarrays from 208 patients with breast carcinomas, of whom 52 had developed BrM. Clinical and pathological characteristics and biomarkers expression in Luminal and non-Luminal patients were analyzed using a multivariate logistic regression model adjusted for covariates, and brain metastasis-free survival (BrMFS) was estimated using the Kaplan-Meier method and the Cox proportional hazards model. FN14 expression was associated with BrM progression mainly in Luminal breast cancer patients with a sensitivity (53.85%) and specificity (89.60%) similar to Her2 expression (46.15 and 89.84%, respectively). Moreover, the likelihood to develop BrM in FN14-positive Luminal carcinomas increased 36.70-fold (3.65-368.25, p = 0.002). Furthermore, the worst prognostic factor for BrMFS in patients with Luminal carcinomas was FN14 overexpression (HR = 8.25; 95% CI: 2.77-24.61; p = 0.00015). In these patients, GRP94 overexpression also increased the risk of BrM (HR = 3.58; 95% CI: 0.98-13.11; p = 0.054-Wald test). Therefore, FN14 expression in Luminal breast carcinomas is a predictive/prognostic biomarker of BrM, which combined with GRP94 predicts BrM progression in non-Luminal tumors 4.04-fold (1.19-8.22, p = 0.025), suggesting that both biomarkers are useful to stratify BrM risk at early diagnosis. We propose a new follow-up protocol for the early prevention of clinical BrM of breast cancer patients with BrM risk.

TWEAK/Fn14 Activation Participates in Skin Inflammation

Tumor necrosis factor- (TNF-) like weak inducer of apoptosis (TWEAK) participates in multiple biological activities via binding to its sole receptor-fibroblast growth factor-inducible 14 (Fn14). The TWEAK/Fn14 signaling pathway is activated in skin inflammation and modulates the inflammatory responses of keratinocytes by activating nuclear factor-κB signals and enhancing the production of several cytokines, including interleukins, monocyte chemotactic protein-1, RANTES (regulated on activation, normal T cell expressed and secreted), and interferon gamma-induced protein 10. Mild or transient TWEAK/Fn14 activation contributes to tissular repair and regeneration while excessive or persistent TWEAK/Fn14 signals may lead to severe inflammatory infiltration and tissue damage. TWEAK also regulates cell fate of keratinocytes, involving the function of Fn14-TNF receptor-associated factor-TNF receptor axis. By recruiting inflammatory cells, promoting cytokine production, and regulating cell fate, TWEAK/Fn14 activation plays a pivotal role in the pathogenesis of various skin disorders, such as psoriasis, atopic dermatitis, cutaneous vasculitis, human papillomavirus infection and related skin tumors, and cutaneous autoimmune diseases. Therefore, the TWEAK/Fn14 pathway may be a potential target for the development of novel therapeutics for skin inflammatory diseases.

WITHDRAWN: Diversity of immunoglobulin G functions

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