The anti-apoptotic activity of BAG3 is restricted by caspases and the proteasome

Identification of the first-in-class dual inhibitor targeting BAG3 and HSP70 proteins to disrupt multiple chaperone pathways

In the complex network of cellular physiology, the maintenance of cellular proteostasis emerges as a critical factor for cell survival, particularly under stress conditions. This homeostasis is largely governed by a sophisticated network of molecular chaperones and co-chaperones, among which Bcl-2-associated athanogene 3 (BAG3), able to interact with the ATPase domain of Heat Shock Protein 70 (HSP70), plays a pivotal role. The BAG3-HSP70 functional module is not only essential for cellular homeostasis but is also involved in the pathogenesis of various diseases, including cancer, neurodegenerative disorders, and cardiac dysfunction, making it an attractive target for therapeutic intervention. Inspired by our continuous interest in the development of new chemical platforms able to interfere with BAG3 protein, herein we report the discovery of compound 16, the first-in-class BAG3/HSP70 dual modulator, obtained by combining the multicomponent Ugi reaction with the alkyne-azide Huisgen procedure in a sequential tandem reaction approach. Through a combination of biophysical analysis, biochemical assays, and cell-based studies, we elucidated the mechanism of action of this inhibitor and assessed its potential as a therapeutic agent. Hence, this study can open new avenues for the development of novel anticancer strategies that leverage the simultaneous disruption of multiple chaperone pathways.

Identification of a New Promising BAG3 Modulator Featuring the Imidazopyridine Scaffold

The antiapoptotic BAG3 protein plays a crucial role in cellular proteostasis and it is involved in several signalling pathways governing cell proliferation and survival. Owing to its multimodular structure, it possesses an extensive interactome including the molecular chaperone HSP70 and other specific cellular partners, which make it an eminent factor in several pathologies, particularly in cancer. Despite its potential as a therapeutic target, very few BAG3 modulators have been disclosed so far. Here we describe the identification of a promising BAG3 modulator able to bind the BAG domain of the protein featuring an imidazopyridine scaffold and obtained through the application of the Groebke-Blackburn-Bienaymé chemical synthesis procedure. The disclosed compound 10 showed a relevant cytotoxic activity, and in line with the biological profile of BAG3 disruption, it induced the activation of caspase 3 and 9.

Corelating the molecular structure of BAG3 to its oncogenic role

BAG3 is a multifaceted protein characterised by having WW domain, PXXP motif and BAG domain. This protein gets upregulated during malignant transformation of cells and has been associated with poorer survival of patients. Procancerous activity of BAG domain of BAG3 is well documented. BAG domain interacts with ATPase domain of Hsp-70 preventing protein delivery to proteasome. This impediment results in enhanced cell survival, proliferation, resistance to apoptosis and chemoresistance. Besides BAG domain other two domains/motifs of BAG3 are under research vigilance to explore its further oncogenic role. This review summarises the role of different structural determinants of BAG3 in elevating oncogenesis. Based on the already existing findings, more interacting partners of BAG3 are anticipated. The anticipated partners of BAG3 can shed a wealth of information into the mechanistic insights of its proproliferative role. Proper insights into the mechanistic details adopted by BAG3 to curtail/elaborate activity of anticipated interacting partners can serve as a potent target for development of therapeutic interventions.

Distal hereditary motor neuronopathy as a new phenotype associated with variants in BAG3

OBJECTIVE

To describe a new phenotype associated with a novel variant in BAG3: autosomal dominant adult-onset distal hereditary motor neuronopathy.

METHODS

This study enrolled eight affected individuals from a single family and included a comprehensive evaluation of the clinical phenotype, neurophysiologic testing, muscle MRI, muscle biopsy and western blot of BAG3 protein in skeletal muscle. Genetic workup included whole exome sequencing and segregation analysis of the detected variant in BAG3.

RESULTS

Seven patients developed slowly progressive and symmetric distal weakness and atrophy of lower limb muscles, along with absent Achilles reflexes. The mean age of onset was 46 years. The neurophysiological examination was consistent with the diagnosis of distal motor neuronopathy. One 57-year-old female patient was minimally symptomatic. The pattern of inheritance was autosomal dominant, with one caveat: one female patient who was an obligate carrier of the variant died at the age of 73 years without exhibiting any muscle weakness. The muscle biopsies revealed neurogenic changes. A novel heterozygous truncating variant c.1513_1514insGGAC (p.Val505GlyfsTer6) in the gene BAG3 was identified in all affected family members.

CONCLUSIONS

We report an autosomal dominant adult-onset distal hereditary motor neuronopathy with incomplete penetrance in women as a new phenotype related to a truncating variant in the BAG3 gene. Our findings expand the phenotypic spectrum of BAG3-related disorders, which previously included dilated cardiomyopathy, myofibrillar myopathy and adult-onset Charcot-Marie-Tooth type 2 neuropathy. Variants in BAG3 should be considered in the differential diagnosis of distal hereditary motor neuronopathies.

Bioinformatics analysis of the clinicopathological and prognostic significance of BAG3 mRNA in gynecological cancers

BAG3 is a co-chaperone BAG family protein that plays important roles in protein homeostasis, cell survival, cell motility, and tumour metastasis. This study aimed to clarify the clinicopathological and prognostic implications of BAG3 mRNA expression in tumours. We performed bioinformatics analysis on BAG3 mRNA expression using TCGA, XIANTAO, UALCAN, and Kaplan-Meier plotter databases. BAG3 mRNA expression was downregulated in breast and endometrial cancers and positively correlated with favourable PAM50 subtyping in breast cancer，clinical stage and short overall survival in ovarian cancer and negatively correlated with T stage, clinical stage, and histological grade in cervical and endometrial cancers. The top BAG3-related pathways included ligand-receptor interactions and activity, DNA packaging and nucleosomes, hormonal responses, membrane regions, microdomains and rafts, and endosomes in breast cancer; ligand-receptor interactions, transmembrane transporters and channels, cell adhesion, and keratinisation in cervical cancer; ligand-receptor interactions, anion transmembrane transporters, lipoproteins, keratinisation, cell adhesion, and protein processing in endometrial cancer; metabolism of porphyrin, chlorophyll, pentose, uronic acid, ascorbate, and alternate and cell adhesion in ovarian cancer. BAG3 expression could represent a potential marker for carcinogenesis, histogenesis, aggressive behaviours, and prognosis in gynecological cancers.IMPACT STATEMENTWhat is already known on this subject? BAG3 regulates cell activity, autophagy, and resistance to apoptosis through multiple domains and plays an important role in tumour development. BAG3 positively regulates tumour cell invasion and migration in cervical and ovarian cancers.What do the results of this study add? BAG3 expression is closely associated with histogenesis, clinicopathology, and prognosis in gynecological cancers and is involved in signalling pathways associated with the control of cell proliferation, migration, invasion, and drug resistance in tumours.What are the implications of these findings for clinical practice and/or further research? Abnormal BAG3 expression can be employed as a possible marker of tumour development, invasion, and prognosis, providing new ideas for treating cancer.

Chicken pituitary transcriptomic responses to acute heat stress

BACKGROUND

Poultry production is vulnerable to increasing temperatures in terms of animal welfare and in economic losses. With the predicted increase in global temperature and the number and severity of heat waves, it is important to understand how chickens raised for food respond to heat stress. This knowledge can be used to determine how to select chickens that are adapted to thermal challenge. As neuroendocrine organs, the hypothalamus and pituitary provide systemic regulation of the heat stress response.

METHODS AND RESULTS

Here we report a transcriptome analysis of the pituitary response to acute heat stress. Chickens were stressed for 2 h at 35 °C (HS) and transcriptomes compared with birds maintained in thermoneutral temperatures (25 °C).

CONCLUSIONS

The observations were evaluated in the context of ontology terms and pathways to describe the pituitary response to heat stress. The pituitaries of heat stressed birds exhibited responses to hyperthermia through altered expression of genes coding for chaperones, cell cycle regulators, cholesterol synthesis, transcription factors, along with the secreted peptide hormones, prolactin, and proopiomelanocortin.

BAG3 Proteomic Signature under Proteostasis Stress

The multifunctional HSP70 co-chaperone BAG3 (BCL-2-associated athanogene 3) represents a key player in the quality control of the cellular proteostasis network. In response to stress, BAG3 specifically targets aggregation-prone proteins to the perinuclear aggresome and promotes their degradation via BAG3-mediated selective macroautophagy. To adapt cellular homeostasis to stress, BAG3 modulates and functions in various cellular processes and signaling pathways. Noteworthy, dysfunction and deregulation of BAG3 and its pathway are pathophysiologically linked to myopathies, cancer, and neurodegenerative disorders. Here, we report a BAG3 proteomic signature under proteostasis stress. To elucidate the dynamic and multifunctional action of BAG3 in response to stress, we established BAG3 interactomes under basal and proteostasis stress conditions by employing affinity purification combined with quantitative mass spectrometry. In addition to the identification of novel potential BAG3 interactors, we defined proteins whose interaction with BAG3 was altered upon stress. By functional annotation and protein-protein interaction enrichment analysis of the identified potential BAG3 interactors, we confirmed the multifunctionality of BAG3 and highlighted its crucial role in diverse cellular signaling pathways and processes, ensuring cellular proteostasis and cell viability. These include protein folding and degradation, gene expression, cytoskeleton dynamics (including cell cycle and transport), as well as granulostasis, in particular.

Cytoprotective effect of 2-carbomethoxy-2,3-epoxy-3-prenyl-1,4-naphthoquinone (CMEP-NQ) is mediated by the inhibition of BAK-dependent mitochondrial apoptosis pathway

The inhibitory mechanism of 2-carbomethoxy-2,3-epoxy-3-prenyl-1,4-naphthoquinone (CMEP-NQ) against apoptosis induced by the microtubule-damaging agents (MDAs), nocodazole (NOC) and 2-methoxyestradiol (2-MeO-E₂), or a DNA-damaging agent (DDA), camptothecin (CPT) were investigated in human Jurkat T cell clones (J/Neo and J/BCL-XL cells). Treatment of J/Neo cells with NOC, 2-MeO-E₂, or CPT caused cytotoxicity and apoptotic DNA fragmentation but these events were significantly attenuated in the presence of CMEP-NQ. Although not only MDA (NOC or 2-MeO-E₂)-induced mitotic arrest, CDK1 activation, and BCL-2, BCL-XL and BIM phosphorylation, but also DDA (CPT)-induced S-phase arrest and ATM-CHK1/CHK2-p53 pathway activation were not or were barely affected in the presence of CMEP-NQ, the levels of anti-apoptotic BAG3 and MCL-1, which were markedly downregulated after MDA- or DDA-treatment, were rather elevated by CMEP-NQ. Under the same conditions, MDA- or DDA-induced mitochondrial apoptotic events including BAK activation, mitochondrial membrane potential (Δψm) loss, caspase-9 activation, and PARP cleavage were significantly inhibited by CMEP-NQ. While MDA- or DDA-induced sub-G₁ peak and Δψm loss were abrogated in J/BCL-XL cells, MDA-induced mitotic arrest and DDA-induced S-arrest were more apparent in J/BCL-XL cells than in J/Neo cells. Simultaneously, the induced cell cycle arrest in J/BCL-XL cells was not significantly disturbed by CMEP-NQ. MDA- or DDA-treatment caused intracellular reactive oxygen species (ROS) production; however, MDA- or DDA-induced ROS production was almost completely abrogated in J/BCL-XL cells. MDA- or DDA-induced ROS production in J/Neo cells was significantly suppressed by CMEP-NQ, but the suppressive effect was hardly observed in J/BCL-XL cells. Together, these results show that CMEP-NQ efficiently protects Jurkat T cells from apoptotic cell death via the elevation of BAG3 and MCL-1 levels, which results in the inhibition of intrinsic BAK-dependent mitochondrial apoptosis pathway, as does the overexpression of BCL-XL.

The Role of the Multifunctional BAG3 Protein in Cellular Protein Quality Control and in Disease

In neurons, but also in all other cells the complex proteostasis network is monitored and tightly regulated by the cellular protein quality control (PQC) system. Beyond folding of newly synthesized polypeptides and their refolding upon misfolding the PQC also manages the disposal of aberrant proteins either by the ubiquitin-proteasome machinery or by the autophagic-lysosomal system. Aggregated proteins are primarily degraded by a process termed selective macroautophagy (or aggrephagy). One such recently discovered selective macroautophagy pathway is mediated by the multifunctional HSP70 co-chaperone BAG3 (BCL-2-associated athanogene 3). Under acute stress and during cellular aging, BAG3 in concert with the molecular chaperones HSP70 and HSPB8 as well as the ubiquitin receptor p62/SQSTM1 specifically targets aggregation-prone proteins to autophagic degradation. Thereby, BAG3-mediated selective macroautophagy represents a pivotal adaptive safeguarding and emergency system of the PQC which is activated under pathophysiological conditions to ensure cellular proteostasis. Interestingly, BAG3-mediated selective macroautophagy is also involved in the clearance of aggregated proteins associated with age-related neurodegenerative disorders, like Alzheimer’s disease (tau-protein), Huntington’s disease (mutated huntingtin/polyQ proteins), and amyotrophic lateral sclerosis (mutated SOD1). In addition, based on its initial description BAG3 is an anti-apoptotic protein that plays a decisive role in other widespread diseases, including cancer and myopathies. Therefore, in the search for novel therapeutic intervention avenues in neurodegeneration, myopathies and cancer BAG3 is a promising candidate.

Induction and adaptation of chaperone-assisted selective autophagy CASA in response to resistance exercise in human skeletal muscle

Chaperone-assisted selective autophagy (CASA) is a tension-induced degradation pathway essential for muscle maintenance. Impairment of CASA causes childhood muscle dystrophy and cardiomyopathy. However, the importance of CASA for muscle function in healthy individuals has remained elusive so far. Here we describe the impact of strength training on CASA in a group of healthy and moderately trained men. We show that strenuous resistance exercise causes an acute induction of CASA in affected muscles to degrade mechanically damaged cytoskeleton proteins. Moreover, repeated resistance exercise during 4 wk of training led to an increased expression of CASA components. In human skeletal muscle, CASA apparently acts as a central adaptation mechanism that responds to acute physical exercise and to repeated mechanical stimulation.

Expression and clinical role of chemoresponse-associated genes in ovarian serous carcinoma

OBJECTIVE

To validate our earlier observation that 11 chemoresistance-associated mRNAs are molecular markers of poor overall survival in ovarian serous carcinoma.

METHODS

Ovarian serous carcinomas (n=112) and solid metastases (n=63; total=175) were analyzed for mRNA expression of APC, BAG3, EGFR, S100A10, ITGAE, MAPK3, TAP1, BNIP3, MMP9, FASLG and GPX3 using quantitative real-time PCR. mRNA expression was studied for association with clinicopathologic parameters and survival. Tumor heterogeneity was assessed in 20 cases with >1 specimen per patient. APC, BAG3, S100A10 and ERK1 protein expression by immunohistochemistry was analyzed in 58 specimens (38 primary carcinomas, 20 metastases).

RESULTS

BAG3 (p=0.013), TAP1 (p=0.014), BNIP3 (p<0.001) and MMP9 (p=0.036) were overexpressed in primary tumors, whereas S100A10 (p=0.027) and FASLG (p=0.006) were overexpressed in metastases. Analysis of patient-matched primary carcinomas and metastases showed overexpression of APC (p=0.022), MAPK3 (p=0.002) and BNIP3 (p=0.004) in the former. In primary carcinomas, higher APC (p=0.003) and MAPK3 (p=0.005) levels were related to less favorable chemoresponse. Higher S100A10 (p=0.029) and MAPK3 (p=0.041) levels were related to primary chemoresistance. Higher BAG3 (p=0.026) and APC (p=0.046) levels in primary carcinomas were significantly related to poor overall survival in univariate, though not in multivariate survival analysis. S100A10 protein expression was related to poor chemoresponse (p=0.002) and shorter overall (p=0.005) and progression-free (p<0.001) survival, the latter finding retained in multivariate analysis (p=0.035).

CONCLUSIONS

Our data provide evidence of heterogeneity in ovarian serous carcinoma and identify APC, MAPK3, BAG3 and S100A10 as potential biomarkers of poor chemotherapy response and/or poor outcome in this cancer.

Development of a multiparameter flow cytometric assay as a potential biomarker for homologous recombination deficiency in women with high-grade serous ovarian cancer

OBJECTIVES

PARP inhibitors (PARPi) are a novel class of drugs with activity in patients with acquired or germline homologous recombination (HR) deficiency-associated high-grade serous ovarian cancer (HGSOC). We hypothesized that measuring γH2AX as an indicator of DNA double-strand breaks (DSB), and MRE11 or RAD51 as an indicator of DSB repair, would reflect HR status and predict response to PARPi-based therapy. Our aim was to develop and use high-throughput multiparametric flow cytometry to quantify γH2AX with MRE11 or RAD51 in PBMCs as a readily available surrogate.

METHODS

Healthy donor PBMCs were used for assay development and optimization. We validated induction of γH2AX, MRE11 and RAD51 by staining with fluorophore-conjugated antibodies. The multiparameter flow cytometric method was applied to PBMC samples from recurrent HGSOC patients who were treated with PARPi, olaparib and carboplatin.

RESULTS

Stimulation was necessary for quantification of a DNA damage response to olaparib/carboplatin in healthy donor PBMCs. The flow cytometric protocol could not distinguish between cytoplasmic and nuclear RAD51, erroneously indicating activation in response to injury. Thus, MRE11 was selected as the marker of DSB repair. PBMCs from 15 recurrent HGSOC patients were then examined. Patients who did not respond to PARPi therapy had a significantly higher pre-treatment level of γH2AX (p = 0.01), and a higher ratio of γH2AX/MRE11 (11.0 [3.5-13.2] v. 3.3 [2.8-9.9], p < 0.03) compared with responders.

CONCLUSIONS

We successfully developed and applied a multiparameter flow cytometry assay to measure γH2AX and MRE11 in PBMCs. Prospective studies will be required to validate this surrogate biomarker assay as a potential predictive biomarker of PARPi-based therapy.

Personalization of cancer treatment using predictive simulation

Background

The personalization of cancer treatments implies the reconsideration of a one-size-fits-all paradigm. This move has spawned increased use of next generation sequencing to understand mutations and copy number aberrations in cancer cells. Initial personalization successes have been primarily driven by drugs targeting one patient-specific oncogene (e.g., Gleevec, Xalkori, Herceptin). Unfortunately, most cancers include a multitude of aberrations, and the overall impact on cancer signaling and metabolic networks cannot be easily nullified by a single drug.

Methods

We used a novel predictive simulation approach to create an avatar of patient cancer cells using point mutations and copy number aberration data. Simulation avatars of myeloma patients were functionally screened using various molecularly targeted drugs both individually and in combination to identify drugs that are efficacious and synergistic. Repurposing of drugs that are FDA-approved or under clinical study with validated clinical safety and pharmacokinetic data can provide a rapid translational path to the clinic. High-risk multiple myeloma patients were modeled, and the simulation predictions were assessed ex vivo using patient cells.

Results

Here, we present an approach to address the key challenge of interpreting patient profiling genomic signatures into actionable clinical insights to make the personalization of cancer therapy a practical reality. Through the rational design of personalized treatments, our approach also targets multiple patient-relevant pathways to address the emergence of single therapy resistance. Our predictive platform identified drug regimens for four high-risk multiple myeloma patients. The predicted regimes were found to be effective in ex vivo analyses using patient cells.

Conclusions

These multiple validations confirm this approach and methodology for the use of big data to create personalized therapeutics using predictive simulation approaches.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0399-y) contains supplementary material, which is available to authorized users.

Overexpression of BAT3 alleviates prion protein fragment PrP106-126-induced neuronal apoptosis

BACKGROUNDS AND AIMS

Prion diseases are a group of infectious neurodegenerative diseases characterized by neuronal death and degeneration. Human leukocyte antigen-B-associated transcript 3 (BAT3) is an important apoptosis regulator. We therefore investigated the interactions between BAT3 and prion protein and the potential role of BAT3 in PrP106-126-induced apoptosis.

METHODS

BAT3 and prion protein were overexpressed in Hela, Neuro2A, or primary neuronal cells by transfection with BAT3-HA or PRNP-EGFP expression plasmids and their relationship studied by immunofluorescence and Western blotting. The effect of BAT3 on PrP106-126-induced cytotoxicity and apoptosis was detected by the CCK-8 assay and terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. The expression of cytochrome c and Bcl-2 was examined by Western blotting.

RESULTS

BAT3 interacted with prion protein and enhanced PrP expression. After PrP106-126 peptide treated, BAT3 was transported from the nucleus to cytoplasm, increased cell viability, and protected neurons from PrP106-126-induced apoptosis through stabilizing the level of Bcl-2 protein and inhibiting the release of cytochrome c to cytoplasm.

CONCLUSIONS

Our present data showed a novel molecular mechanism of PrP106-126-induced apoptotic process regulation through the overexpression of BAT3, which may be important for the basic regulatory mechanism of neuron survival in prion diseases and associated neurodegenerative diseases in vivo.

L-asparaginase inhibits invasive and angiogenic activity and induces autophagy in ovarian cancer

Recent work identified L-asparaginase (L-ASP) as a putative therapeutic target for ovarian cancer. We suggest that L-ASP, a dysregulator of glycosylation, would interrupt the local microenvironment, affecting the ovarian cancer cell-endothelial cell interaction and thus angiogenesis without cytotoxic effects. Ovarian cancer cell lines and human microvascular endothelial cells (HMVEC) were exposed to L-ASP at physiologically attainable concentrations and subjected to analyses of endothelial tube formation, invasion, adhesion and the assessment of sialylated proteins involved in matrix-associated and heterotypic cell adhesion. Marked reduction in HMVEC tube formation in vitro, HMVEC and ovarian cancer cell invasion, and heterotypic cell-cell and cell-matrix adhesion was observed (P < 0.05-0.0001). These effects were associated with reduced binding to ß1integrin, activation of FAK, and cell surface sialyl Lewis(X) (sLe(x)) expression. No reduction in HMVEC E-selectin expression was seen consistent with the unidirectional inhibitory actions observed. L-ASP concentrations were non-toxic to either ovarian cancer or HMVEC lines in the time frame of the assays. However, early changes of autophagy were observed in both cell types with induction of ATG12, beclin-1, and cleavage of LC-3, indicating cell injury did occur. These data and the known mechanism of action of L-ASP on glycosylation of nascent proteins suggest that L-ASP reduces of ovarian cancer dissemination and progression through modification of its microenvironment. The reduction of ovarian cancer cell surface sLe(x) inhibits interaction with HMVEC and thus HMVEC differentiation into tubes, inhibits interaction with the local matrix reducing invasive behaviour, and causes cell injury initiating autophagy in tumour and vascular cells.

BAT3 regulates Mycobacterium tuberculosis protein ESAT-6-mediated apoptosis of macrophages

HLA-B-associated transcript 3 (BAT3), also known as Scythe or BAG6, is a nuclear protein implicated in the control of apoptosis and natural killer (NK) cell-dendritic cell (DC) interaction. We demonstrate that BAT3 modulates the immune response by regulating the function of macrophages. BAT3 is released by macrophages in vitro and it down-regulates nitric oxide and proinflammatory cytokines release in IFN-γ and LPS stimulated macrophages. Furthermore, Mycobacterium tuberculosis-derived protein ESAT-6 (Rv3875) induced transient increase in the expression and release of BAT3 in macrophages. We show that induction of apoptosis by ESAT-6 is dependent on the cleavage of BAT3 by caspase-3 and proteasomal degradation. Our results also indicate that BAT3 regulates ESAT-6-induced apoptosis by interacting with anti-apoptotic protein BCL-2. Taken together, the data suggest that BAT3 plays a role in the early immune response to M. tuberculosis infection and may be a key protein associated with the fate of antigen presenting cells during infection.

[BAG family gene and its relationship with lung adenocarcinoma susceptibility]

BACKGROUND AND OBJECTIVE

BAG genes (Bcl-2-associated athanogene) belong to a recently discovered multifunctional anti-apoptosis gene family that regulate various physiological processes which include apoptosis, tumorigenesis, neural differentiation, stress response and cell cycle and so on. The expression status of BAG family genes are related to certain tumor incidence and prognosis. The aim of this study is to explore the association of the BAG family gene expression status with the susceptibility of lung adenocarcinoma.

METHODS

The gene expression data of BAG family genes from 29 cases of lung adenocarcinoma tissues and matched pericancerous lung tissues were generated by microarray chips. Cox regression was used to analyze the association between the expression of BAG family genes and the susceptibility of lung adenocarcinoma and the results were verified by GEO database.

RESULTS

The expression levels of BAG-1, BAG-2, BAG-5 in cancer tissues were significantly downregulated compared with matched pericancerous lung tissues and were protective factors of lung adenocarcinoma (P < 0.05, OR < 1); while the expression level of BAG-4 in cancer tissues were remarkably upregulated compared with the matched pericancerous lung tissues and was risk factor of lung adenocarcinoma (P < 0.05, OR > 1).

CONCLUSIONS

BAG-1, BAG-2, BAG-5 might be the potential protective factors while BAG-4 is possible risk factor of lung adenocarcinoma.

Characterization of BAG3 cleavage during apoptosis of pancreatic cancer cells

Caspases are a conserved family of cell death proteases that cleave intracellular substrates at Asp residues to modify their function and promote apoptosis. In this report, we identify BAG3 as a novel caspases substrate. Here, we show that one of these BAG proteins, BAG3, is cleaved during apoptosis. BAG3 cleavage is inhibited by several different caspase inhibitors. The analysis of BAG3 cleavage by recombinant caspase proteins shows that BAG3 is efficiently cleaved by caspase-3, to a smaller extent by caspases-1 and -8, and relatively inefficient by caspase-9. Cleavage of the BAG3 protein occurs in the C-terminal part of the protein majorly at Asp347 (KEVD347 downward arrow S) in vitro and in pancreatic cancer SW1990 and PANC-1 cells undergoing apoptosis. We also demonstrate that unlike cleavage of Bcl-2 and Bcl-XL, cleaved form of BAG3 does not result in pro-apoptotic fragments, however, cleavage of BAG3 lead to loss its per se anti-apoptotic property. This novel regulation of BAG3 may have important implications for its role in apoptosis.