Margot De Marco

IKKγ 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-κB pathway. Indeed, we demonstrate that BAG3 alters the interaction between HSP70 and IKKγ, increasing availability of IKKγ and protecting it from proteasome-dependent degradation; this, in turn, results in increased NF-κB 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.

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.

BAG3 promotes pancreatic ductal adenocarcinoma growth by activating stromal macrophages

The incidence and death rate of pancreatic ductal adenocarcinoma (PDAC) have increased in recent years, therefore the identification of novel targets for treatment is extremely important. Interactions between cancer and stromal cells are critically involved in tumour formation and development of metastasis. Here we report that PDAC cells secrete BAG3, which binds and activates macrophages, inducing their activation and the secretion of PDAC supporting factors. We also identify IFITM-2 as a BAG3 receptor and show that it signals through PI3K and the p38 MAPK pathways. Finally, we show that the use of an anti-BAG3 antibody results in reduced tumour growth and prevents metastasis formation in three different mouse models. In conclusion, we identify a paracrine loop involved in PDAC growth and metastatic spreading, and show that an anti-BAG3 antibody has therapeutic potential.

HIV-1 Tat protein induces glial cell autophagy through enhancement of BAG3 protein levels

BAG3 protein has been described as an anti-apoptotic and pro-autophagic factor in several neoplastic and normal cells. We previously demonstrated that BAG3 expression is elevated upon HIV-1 infection of glial and T lymphocyte cells. Among HIV-1 proteins, Tat is highly involved in regulating host cell response to viral infection. Therefore, we investigated the possible role of Tat protein in modulating BAG3 protein levels and the autophagic process itself. In this report, we show that transfection with Tat raises BAG3 levels in glioblastoma cells. Moreover, BAG3 silencing results in highly reducing Tat- induced levels of LC3-II and increasing the appearance of sub G0/G1 apoptotic cells, in keeping with the reported role of BAG3 in modulating the autophagy/apoptosis balance. These results demonstrate for the first time that Tat protein is able to stimulate autophagy through increasing BAG3 levels in human glial cells.

BAG3 is a novel serum biomarker for pancreatic adenocarcinomas.

to the small number of patients (62.5 vs. 37.5 % , P = 0.11). However, when comparing median cumulative exposure to RBV between groups as measured by the area under the drug exposure curve from week 0 to 12 based on biweekly measurements of RBV plasma levels rather than RBV dosage per se , cumulative exposure to RBV above ≥ 224.3 μ g / dl / day was signifi cantly associated with SVR (odds ratio 8.8; confi dence interval 1.35 – 57.43, P = 0.02) ( Figure 1 ). Anemia in group A was more severe than in group B (mean hemoglobin 99.6 vs. 106.3 g / l; P < 0.001), but well manageable with erythropoietin beta at doses between 9,000 and 30,000 IU per week according to a recently proposed consensus ( 10 ) Except for anemia, adverse events were similar in both groups. In conclusion — and in accordance with the study by Jin et al. ( 7 ) — optimal exposure to RBV guided by therapeutic drug monitoring signifi cantly improves SVR in patients with CHC genotype 1. Th erefore, regular RBV plasma level measurements at least for the fi rst 12 weeks of therapy and RBV dose adjustment may be advocated.

BAG3 protein is induced during cardiomyoblast differentiation and modulates myogenin expression.

Dear Editor, In the program of cardiomyoblast differentiation, induction of proteins that protect cardiomyocytes from stretch and load stress-induced apoptosis has a relevant role. Indeed, cardiomyocytes are intrinsically resistant to apoptosis, due in part to high levels of endogenous caspase inhibitors, anti-apoptotic Bcl-2 proteins and the pro-survival kinase Akt. Among proteins that sustain cardiomyocyte survival, a role is assigned to BAG3. This is a co-chaperone of the heat shock protein (Hsp) 70 that is constitutively present in myocytes and a few other normal cell types, while its expression is induced by a variety of stressful stimuli in leukocytes and other cells; on the other hand, some neoplastic cells constitutively express BAG3, that plays an anti-apoptotic role. Indeed, in osteosarcoma or melanoma cells, BAG3 interferes with the Hsp70mediated delivery of the IKK regulatory subunit, IKKγ to proteasome, thereby sustaining IKKγ intracellular levels, NFκB activation and cell survival. Furthermore, in another neoplastic cell type, i.e., glioblastoma, BAG3 protein retains the antiapoptotic protein BAX in cell cytosol, impeding its translocation to mitochondria and apoptosis triggering (unpublished results). Therefore BAG3 appears to sustain cell survival by more than one mechanism and indeed it can interact with several molecular partners, through its BAG, WW or Pro-rich domains. Mice with homozygous disruption of bag3 gene develop postnatally a fulminant cardiomyopathy characterized by noninflammatory myofibrillar degeneration with BAG3 protein is induced during cardiomyoblast differentiation and modulates myogenin expression

Polymorphisms of the antiapoptotic protein bag3 may play a role in the pathogenesis of tako-tsubo cardiomyopathy

following classes this dependence progressively increased up to the extremely high level in hrv7 class. Thiswaywe have obtained a set of HRV indiceswhich are associated in different extent with HR. Such parameters constitute a perfect material for investigations of the HR contribution to the HRV prognostic power [5]. Moreover, this may be applied not only to the spectral HRV analysis but also to any other analysis of heart rate dynamics which parameters are associated with HR — in such instances the RR-interval tachograms should rather be modified (i.e. divided or multiplied by avRRs) before a given heart rate dynamics is analyzed. Importantly, if one calculates average HRV indices from the indices corresponding to short RR interval segments (e.g. from Holter recordings), one should first obtain the global average HRV indices of all RR interval segments and then divide or multiply them by a global avRR — the division or multiplication for each segment separately may create the situation where a single RR interval segment with unusually slow or fast HR determines the results for a given patient (it is especially likely if one employs high powers of avRR). To conclude, the described approach opens new perspectives for the analysis of HR dynamics, i.e. it makes possible to separate clinical (e.g. prognostic) information coming from average heart rate and from its dynamics.

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 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.

Combined effect of anti-BAG3 and anti-PD-1 treatment on macrophage infiltrate, CD8+ T cell number and tumour growth in pancreatic cancer

We read with great interest the article by Zhang et al 1 showing that CD8+ cell infiltration in pancreatic tumours can be enhanced by depletion of myeloid cells (CD11b+ macrophages and myeloid-derived suppressor cells) and that the depletion of CD11b+ cells resulted in decreased PD-L1 expression on cancer cells thus impairing the triggering of the inhibitory receptor PD-1 on T cells.1 Recruitment and activation of CD8+ lymphocytes in tumours are suppressed by mechanisms only partially understood and rescuing CD8+ cell infiltrate in tumours is one of the objectives of immunotherapies.1 2 Tumour-associated macrophages (TAMs) play a crucial role in the relation between tumour cells and their environment.3 Here, we confirm the interplay between macrophages and CD8+ cells in pancreatic cancer and identify a potential way to exploit this enhancing effect of anti-PD-1 treatment. Indeed, we show that reduction of macrophage infiltrate, through treatment with an anti-Bcl-2-Associated athanoGene 3 (BAG3) antibody,4 results in increased number of CD8+ cells in pancreatic tumours in a murine model. BAG3 is a co-chaperone of …