BAG3 induces α-SMA expression in human fibroblasts and its over-expression correlates with poorer survival in fibrotic cancer patients.

Hypoxia and angiogenesis in solid tumors are often strictly linked to the development of fibrotic tissues, a detrimental event that compromises the antitumor immunity. As a consequence, tumor aggressiveness and poor patient prognosis relate to higher incidence of tissue fibrosis and stromal stiffness. The molecular pathways through which normal fibroblasts are converted in cancer-associated fibroblasts (CAFs) have a central role in the onset of fibrosis in tumor stroma, thus emerging as a strategic target of novel therapeutic approaches for cancer disease. Several studies addressed the role of BAG3 in sustaining growth and survival of cancer cell and also shed light on the different mechanisms in which the intracellular protein is involved. More recently, new pieces of evidence revealed a pivotal role of extracellular BAG3 in pro-tumor cell signaling in the tumor microenvironment, as well as its involvement in the development of fibrosis in tumor tissues. Here we report further data showing the presence of the BAG3 receptor (Interferon-induced transmembrane protein [IFITM]-2) on the plasma membrane of normal dermal fibroblasts and the activity of BAG3 as a factor able to induce the expression of α-smooth muscle actin and the phosphorylation of AKT and focal adhesion kinase, that sustain CAF functions in tumor microenvironment. Furthermore, in agreement with these findings, bag3 gene expression has been analyzed by high throughput RNA sequencing databases from patients-derived xenografts. A strong correlation between bag3 gene expression and patients' survival was found in several types of fibrotic tumors. The results obtained provide encouraging data that identify BAG3 as a promising therapeutic target to counteract fibrosis in tumors.

An emerging role for BAG3 in gynaecological malignancies.

BAG3, a member of the BAG family of co-chaperones, is a multidomain protein with a role in several cellular processes, including the control of apoptosis, autophagy and cytoskeletal dynamics. The expression of bag3 is negligible in most cells but can be induced by stress stimuli or malignant transformation. In some tumours, BAG3 has been reported to promote cell survival and resistance to therapy. The expression of BAG3 has been documented in ovarian, endometrial and cervical cancers, and studies have revealed biochemical and functional connections of BAG3 with proteins involved in the survival, invasion and resistance to therapy of these malignancies. BAG3 expression has also been shown to correlate with the grade of dysplasia in squamous intraepithelial lesions of the uterine cervix. Some aspects of BAG3 activity, such as its biochemical and functional interaction with the human papillomavirus proteins, could help in our understanding of the mechanisms of oncogenesis induced by the virus. This review aims to highlight the potential value of BAG3 studies in the field of gynaecological tumours.

Role of BAG3 in cancer progression: A therapeutic opportunity.

BAG3 is a multifunctional protein that can bind to heat shock proteins (Hsp) 70 through its BAG domain and to other partners through its WW domain, proline-rich (PXXP) repeat and IPV (Ile-Pro-Val) motifs. Its intracellular expression can be induced by stressful stimuli, while is constitutive in skeletal muscle, cardiac myocytes and several tumour types. BAG3 can modulate the levels, localisation or activity of its partner proteins, thereby regulating major cell pathways and functions, including apoptosis, autophagy, mechanotransduction, cytoskeleton organisation, motility. A secreted form of BAG3 has been identified in studies on pancreatic ductal adenocarcinoma (PDAC). Secreted BAG3 can bind to a specific receptor, IFITM2, expressed on macrophages, and induce the release of factors that sustain tumour growth and the metastatic process. BAG3 neutralisation therefore appears to constitute a novel potential strategy in the therapy of PDAC and, possibly, other tumours.

BAG3 Protein Is Over-Expressed in Endometrioid Endometrial Adenocarcinomas.

Endometrioid endometrial cancer is the most common gynaecological tumor in developed countries, and its incidence is increasing. The definition of subtypes, based on clinical and endocrine features or on histopathological characteristics, correlate to some extent with patient's prognosis, but there is substantial heterogeneity within tumor types. The search for molecules and mechanisms implied in determining the progression and the response to therapy for this cancer is still ongoing. BAG3 protein, a member of BAG family of co-chaperones, has a pro-survival role in several tumor types. BAG3 anti-apoptotic properties rely on its characteristic to bind several intracellular partners, thereby, modulating crucial events such as apoptosis, differentiation, cell motility, and autophagy. BAG3 expression in human endometrial cancer tissues was not investigated so far. Here, we show that BAG3 protein levels are elevated in tumoral and hyperplastic cells in respect to normal glands. Furthermore, BAG3 subcellular localization appears to be changed in tumoral compared to normal cells. Our results indicate a possible role for BAG3 protein in the maintenance of cell survival in endometrioid endometrial cancer and suggest that this field of studies is worthy of further investigations. J. Cell. Physiol. 232: 309-311, 2017. © 2016 Wiley Periodicals, Inc.

Role of WT1-ZNF224 interaction in the expression of apoptosis-regulating genes.

The transcription factor Wilms' tumor gene 1, WT1, is implicated both in normal developmental processes and in the generation of a variety of solid tumors and hematological malignancies. Physical interactions of other cellular proteins with WT1 are known to modulate its function. We previously identified the Krüppel-like zinc-finger protein, ZNF224, as a novel human WT1-associating protein that enhances the transcriptional activation of the human vitamin D receptor promoter by WT1. Here, we have analyzed the effects of WT1-ZNF224 interaction on the expression of apoptosis-regulating genes in the chronic myelogenous leukemia (CML) K562 cell line. The results demonstrated that ZNF224 acts in fine tuning of WT1-dependent control of gene expression, acting as a co-activator of WT1 in the regulation of proapoptotic genes and suppressing WT1 mediated transactivation of antiapoptotitc genes. Moreover, the DNA damaging drug cytosine arabinoside (ara-C) induces expression of ZNF224 in K562 cells and this induction enhances cell apoptotic response to ara-C. These findings suggest that ZNF224 can be a mediator of DNA damage-induced apoptosis in leukemia cells.

Plasmacytoids dendritic cells are a therapeutic target in anticancer immunity.

Dendritic cells (DCs) are immunological sentinels of the organism acting as antigen-presenting cells (APC) and are critical for induction of innate and adaptive immunity. Traditionally they are divided in myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs), a rare population of circulating cells that selectively express Toll-like receptors (TLR) 7 and TLR9 and have the capacity to produce large amounts of type I interferons (IFNs) in response to pathogenic agents or danger signals. It has been demonstrated that pDCs can coordinate events during the course of viral infections, allergic and autoimmune diseases and cancer. Through the production of type I IFNs, pDCs initiate protective immunity by activating classical DCs, T cells, natural killer cells and B cells. Upon activation, pDCs also differentiate into mature DCs and may contribute to the contraction of T-cell response. Human pDCs preferentially express immunoglobulin-like transcript 7 (ILT7; LILRA4), which couples with a signaling adapter to activate a prominent immune-receptor tyrosine-based activation motif (ITAM)-mediated signaling pathway. The interaction between ILT7 and bone marrow stromal cell antigen 2 (BST2, CD317) assures an appropriate TLR response by pDCs during viral infections and likely participates in pDCs tumor crosstalk. Moreover these cells seem to play a crucial role in the initiation of the pathological process of autoimmune diseases such as lupus or psoriasis. Despite the fact that their function within a tumor context is still controversial they represent an attractive target for therapeutic manipulation of the immune system to elicit a powerful immune response against tumor antigens in combination with other therapies.

Role of BAG3 protein in leukemia cell survival and response to therapy.

The ability of BAG3, a member of the BAG family of heat shock protein (Hsp) 70 - cochaperones, to sustain the survival of human primary B-CLL and ALL cells was recognized about nine years ago. Since then, the anti-apoptotic activity of BAG3 has been confirmed in other tumor types, where it has been shown to regulate the intracellular concentration and localization of apoptosis-regulating factors, including NF-κB-activating (IKKγ) and Bcl2-family (Bax) proteins. Furthermore, growing evidences support its role in lymphoid and myeloid leukemia response to therapy. Moreover in the last years, the contribution of BAG3 to autophagy, a process known to be involved in the pathogenesis and response to therapy of leukemia cells, has been disclosed, opening a new avenue for the interpretation of the role of this protein in leukemias' biology.

Therapeutic potential of a pyridoxal-based vanadium(IV) complex showing selective cytotoxicity for cancer versus healthy cells.

Vanadium compounds can exert anticancer effects, partly due to inhibition of tyrosine phosphatases. Here, we report the effect of N,N'-ethylenebis (pyridoxylideneiminato) vanadium (IV) complex (Pyr2 enV(IV)), that induced 93% and 57% of cell mortality in A375 (human melanoma) and A549 (human lung carcinoma) cells, respectively; the mortality was <24% in other cancer cell lines and in human normal epidermal keratinocytes, lung cells and peripheral blood mononuclear cells. The mechanism of Pyr2 enV(IV) effect relied on apoptosis induction; this was triggered by ROS increase, followed by mitochondrial membrane depolarization. Indeed, the addition of N-acetyl cysteine to cell cultures abated Pyr2 enV(IV)-induced apoptosis. These results disclose the pro-apoptotic activity of Pyr2 enV(IV) and its mechanism, relying on intracellular ROS increase.

Expression of the antiapoptotic protein BAG3 is a feature of pancreatic adenocarcinoma and its overexpression is associated with poorer survival.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most deadly cancers, being the fourth leading cause of cancer-related deaths. Long-term survival reaching 15% is achieved in less than 5% of patients who undergo surgery, and median survival is only 6 months in those with inoperable lesions. A deeper understanding of PDAC biologic characteristics as well as novel prognostic markers are therefore required to improve outcomes. Herein we report that BAG3, a protein with recognized anti-apoptotic activity, was expressed in 346 PDACs analyzed, but was not expressed in the surrounding nonneoplastic tissue. In a cohort of 66 patients who underwent radical resection (R0), survival was significantly shorter in patients with high BAG3 expression (median, 12 months) than in those with low BAG3 expression (median, 23 months) (P = 0.001). Furthermore, we report that BAG3 expression in PDAC-derived cell lines protects from apoptosis and confers resistance to gemcitabine, offering a partial explanation for the survival data. Our results indicate that BAG3 has a relevant role in PDAC biology, and suggest that BAG3 expression level might be a potential marker for prediction of patient outcome.

IKK{gamma} protein is a target of BAG3 regulatory activity in human tumor growth.

BAG3, a member of the BAG family of heat shock protein (HSP) 70 cochaperones, is expressed in response to stressful stimuli in a number of normal cell types and constitutively in a variety of tumors, including pancreas carcinomas, lymphocytic and myeloblastic leukemias, and thyroid carcinomas. Down-regulation of BAG3 results in cell death, but the underlying molecular mechanisms are still elusive. Here, we investigated the molecular mechanism of BAG3-dependent survival in human osteosarcoma (SAOS-2) and melanoma (M14) cells. We show that bag3 overexpression in tumors promotes survival through the NF-kappaB pathway. Indeed, we demonstrate that BAG3 alters the interaction between HSP70 and IKKgamma, increasing availability of IKKgamma and protecting it from proteasome-dependent degradation; this, in turn, results in increased NF-kappaB activity and survival. These results identify bag3 as a potential target for anticancer therapies in those tumors in which this gene is constitutively expressed. As a proof of principle, we show that treatment of a mouse xenograft tumor model with bag3siRNA-adenovirus that down-regulates bag3 results in reduced tumor growth and increased animal survival.

Pancreatic Cancer-Secreted Proteins: Targeting Their Functions in Tumor Microenvironment.

Pancreatic Ductal Adenocarcinoma (PDAC) is a ravaging disease with a poor prognosis, requiring a more detailed understanding of its biology to foster the development of effective therapies. The unsatisfactory results of treatments targeting cell proliferation and its related mechanisms suggest a shift in focus towards the inflammatory tumor microenvironment (TME). Here, we discuss the role of cancer-secreted proteins in the complex TME tumor-stroma crosstalk, shedding lights on druggable molecular targets for the development of innovative, safer and more efficient therapeutic strategies.

Spike-mediated viral membrane fusion is inhibited by a specific anti-IFITM2 monoclonal antibody.

The early steps of viral infection involve protein complexes and structural lipid rearrangements which characterize the peculiar strategies of each virus to invade permissive host cells. Members of the human immune-related interferon-induced transmembrane (IFITM) protein family have been described as inhibitors of the entry of a broad range of viruses into the host cells. Recently, it has been shown that SARS-CoV-2 is able to hijack IFITM2 for efficient infection. Here, we report the characterization of a newly generated specific anti-IFITM2 mAb able to impair Spike-mediated internalization of SARS-CoV-2 in host cells and, consequently, to reduce the SARS-CoV-2 cytopathic effects and syncytia formation. Furthermore, the anti-IFITM2 mAb reduced HSVs- and RSV-dependent cytopathic effects, suggesting that the IFITM2-mediated mechanism of host cell invasion might be shared with other viruses besides SARS-CoV-2. These results show the specific role of IFITM2 in mediating viral entry into the host cell and its candidacy as a cell target for antiviral therapeutic strategies.

Pancreatic beta-cell specific BAG3 knockout results in chronic hyperinsulinemia inducing insulin resistance.

BACKGROUND: Insulin, secreted from pancreatic islets of Langerhans, is of critical importance in regulating glucose homeostasis. Defective insulin secretion and/or the inability of tissues to respond to insulin results in insulin resistance and to several metabolic and organ alterations. We have previously demonstrated that BAG3 regulates insulin secretion. Herein we explored the consequences of beta-cells specific BAG3 deficiency in an animal model. METHODS: We generated a beta-cells specific BAG3 knockout mouse model. Glucose and insulin tolerance tests, proteomics, metabolomics, and immunohistochemical analysis were used to investigate the role of BAG3 in regulating insulin secretion and the effects of chronic exposure to excessive insulin release in vivo. RESULTS: Beta-cells specific BAG3 knockout results in primary hyperinsulinism due to excessive insulin exocytosis finally leading to insulin resistance. We demonstrate that resistance is mainly muscle-dependent while the liver remains insulin sensitive. The chronically altered metabolic condition leads in time to histopathological alterations in different organs. We observe elevated glycogen and lipid accumulation in the liver reminiscent of non-alcoholic fatty liver disease as well as mesangial matrix expansion and thickening of the glomerular basement membrane, resembling the histology of chronic kidney disease. CONCLUSION: Altogether, this study shows that BAG3 plays a role in insulin secretion and provides a model for the study of hyperinsulinemia and insulin resistance.

ß-hairpin peptide that targets vascular endothelial growth factor (VEGF) receptors: design, NMR characterization, and biological activity.

VEGF receptors have been the target of intense research aimed to develop molecules able to inhibit or stimulate angiogenesis. Based on the x-ray structure of the complex placental growth factor-VEGF receptor 1(D2), we designed a VEGF receptor-binding peptide reproducing the placental growth factor ß-hairpin region Gln(87)-Val(100) that is involved in receptor recognition. A conformational analysis showed that the designed peptide adopts the expected fold in pure water. Moreover, a combination of NMR interaction analysis and cell binding studies were used to demonstrate that the peptide targets VEGF receptors. The VEGF receptor 1(D2)-interacting residues were characterized at the molecular level, and they correspond to the residues recognizing the placental growth factor sequence Gln(87)-Val(100). Finally, the peptide biological activity was characterized in vitro and in vivo, and it showed a VEGF-like behavior. Indeed, the peptide activated VEGF-dependent intracellular pathways, induced endothelial cell proliferation and rescue from apoptosis, and promoted angiogenesis in vivo. This compound is one of the few peptides known with proangiogenic activity, which makes it a candidate for the development of a novel peptide-based drug for medical applications in therapeutic angiogenesis.

Matrine modulates HSC70 levels and rescues ΔF508-CFTR.

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent Cl(-) channel located in the plasma membrane, and its malfunction results in cystic fibrosis (CF), the most common lethal genetic disease in Caucasians. Most CF patients carry the deletion of Phe508 (ΔF508 mutation); this mutation prevents the delivery of the CFTR to its correct cellular location, the apical (lumen-facing) membrane of epithelial cells. Molecular chaperones play a central role in determining the fate of ΔF508-CFTR. In this report, we show that the Matrine, a quinolizidine alkaloid, downregulates the expression of the molecular chaperone HSC70 and increases the protein levels of ΔF508-CFTR in human alveolar basal epithelial cells (A549 cell line), stably transfected with a ΔF508-CFTR-expressing construct. Moreover, Matrine induced ΔF508-CFTR release from endoplasmic reticulum to cell cytosol and its localization on the cell membrane. Interestingly, downregulation of HSC70 resulted in increased levels of ΔF508-CFTR complexes with the co-chaperone BAG3 that in addition appeared to co-localize with the mutated protein on the cell surface. These results shed new light on ΔF508-CFTR interactions with proteins of the chaperones/co-chaperones system and could be useful in strategies for future medical treatments for CF.

BAG3 protein is overexpressed in human glioblastoma and is a potential target for therapy.

Glioblastoma multiforme, which represents 80% of malignant gliomas, is characterized by aggressiveness and high recurrence rates. Despite therapeutic advances, patients with glioblastoma multiforme show a poor survival, and identification of novel markers and molecular targets for therapy is needed. A role for BAG3, a member of the BAG family of HSC/HSP70 co-chaperones, in promoting tumor cell growth in vivo has recently been described. We analyzed BAG3 levels by IHC in specimens from patients affected by brain tumors and we found that BAG3, although negative in normal brain tissues, was highly expressed in astrocytic tumors and increasingly expressed in more aggressive types of cancer; it was particularly high in glioblastomas. Down-regulating BAG3 both in vitro and in vivo in a rat glioblastoma model resulted in increased sensitivity to apoptosis, suggesting that BAG3 is a potential target for novel therapies. Finally, we determined that the underlying molecular mechanism requires the formation of a complex of BAG3, HSP70, and BAX that prevents BAX translocation to mitochondria, thus protecting tumor cells from apoptosis. Our data identify BAG3 as a potential marker of glial brain tumor sensitivity to therapy and thus also an attractive candidate for new molecular therapies.