Co-chaperone BAG2 Determines the Pro-oncogenic Role of Cathepsin B in Triple-Negative Breast Cancer Cells

Comparative analysis of BAG1 and BAG2: Insights into their structures, functions and implications in disease pathogenesis

As BAG family members, Bcl-2 associated athanogene family protein 1 (BAG1) and 2 (BAG2) are implicated in multiple cellular processes, including apoptosis, autophagy, protein folding and homeostasis. Although structurally similar, they considerably differ in many ways. Unlike BAG2, BAG1 has four isoforms (BAG1L, BAG1M, BAG1S and BAG1 p29) displaying different expression features and functional patterns. BAG1 and BAG2 play different cellular functions by interacting with different molecules to participate in the regulation of various diseases, including cancer/tumor and neurodegenerative diseases. Commonly, BAG1 acts as a protective factor to predict a good prognosis of patients with some types of cancer or a risk factor in some other cancers, while BAG2 is regarded as a risk factor to promote cancer/tumor progression. In neurodegenerative diseases, BAG2 commonly acts as a neuroprotective factor. In this review, we summarized the differences in molacular structure and biological function between BAG1 and BAG2, as well as the influences of them on pathogenesis of diseases, and explore the prospects for their clinical therapy application by specifying the activators and inhibitors of BAG1 and BAG2, which might provide a better understanding of the underlying pathogenesis and developing the targeted therapy strategies for diseases.

Variants of NAV3, a neuronal morphogenesis protein, cause intellectual disability, developmental delay, and microcephaly

Microtubule associated proteins (MAPs) are widely expressed in the central nervous system, and have established roles in cell proliferation, myelination, neurite formation, axon specification, outgrowth, dendrite, and synapse formation. We report eleven individuals from seven families harboring predicted pathogenic biallelic, de novo, and heterozygous variants in the NAV3 gene, which encodes the microtubule positive tip protein neuron navigator 3 (NAV3). All affected individuals have intellectual disability (ID), microcephaly, skeletal deformities, ocular anomalies, and behavioral issues. In mouse brain, Nav3 is expressed throughout the nervous system, with more prominent signatures in postmitotic, excitatory, inhibiting, and sensory neurons. When overexpressed in HEK293T and COS7 cells, pathogenic variants impaired NAV3 ability to stabilize microtubules. Further, knocking-down nav3 in zebrafish led to severe morphological defects, microcephaly, impaired neuronal growth, and behavioral impairment, which were rescued with co-injection of WT NAV3 mRNA and not by transcripts encoding the pathogenic variants. Our findings establish the role of NAV3 in neurodevelopmental disorders, and reveal its involvement in neuronal morphogenesis, and neuromuscular responses.

Recruitment of BAG2 to DNAJ-PKAc scaffolds promotes cell survival and resistance to drug-induced apoptosis in fibrolamellar carcinoma

The DNAJ-PKAc fusion kinase is a defining feature of fibrolamellar carcinoma (FLC). FLC tumors are notoriously resistant to standard chemotherapies, with aberrant kinase activity assumed to be a contributing factor. By combining proximity proteomics, biochemical analyses, and live-cell photoactivation microscopy, we demonstrate that DNAJ-PKAc is not constrained by A-kinase anchoring proteins. Consequently, the fusion kinase phosphorylates a unique array of substrates, including proteins involved in translation and the anti-apoptotic factor Bcl-2-associated athanogene 2 (BAG2), a co-chaperone recruited to the fusion kinase through association with Hsp70. Tissue samples from patients with FLC exhibit increased levels of BAG2 in primary and metastatic tumors. Furthermore, drug studies implicate the DNAJ-PKAc/Hsp70/BAG2 axis in potentiating chemotherapeutic resistance. We find that the Bcl-2 inhibitor navitoclax enhances sensitivity to etoposide-induced apoptosis in cells expressing DNAJ-PKAc. Thus, our work indicates BAG2 as a marker for advanced FLC and a chemotherapeutic resistance factor in DNAJ-PKAc signaling scaffolds.

Recruitment of BAG2 to DNAJ-PKAc scaffolds promotes cell survival and resistance to drug-induced apoptosis in fibrolamellar carcinoma

The DNAJ-PKAc fusion kinase is a defining feature of the adolescent liver cancer fibrolamellar carcinoma (FLC). A single lesion on chromosome 19 generates this mutant kinase by creating a fused gene encoding the chaperonin binding domain of Hsp40 (DNAJ) in frame with the catalytic core of protein kinase A (PKAc). FLC tumors are notoriously resistant to standard chemotherapies. Aberrant kinase activity is assumed to be a contributing factor. Yet recruitment of binding partners, such as the chaperone Hsp70, implies that the scaffolding function of DNAJ- PKAc may also underlie pathogenesis. By combining proximity proteomics with biochemical analyses and photoactivation live-cell imaging we demonstrate that DNAJ-PKAc is not constrained by A-kinase anchoring proteins. Consequently, the fusion kinase phosphorylates a unique array of substrates. One validated DNAJ-PKAc target is the Bcl-2 associated athanogene 2 (BAG2), a co-chaperone recruited to the fusion kinase through association with Hsp70. Immunoblot and immunohistochemical analyses of FLC patient samples correlate increased levels of BAG2 with advanced disease and metastatic recurrences. BAG2 is linked to Bcl-2, an anti-apoptotic factor that delays cell death. Pharmacological approaches tested if the DNAJ- PKAc/Hsp70/BAG2 axis contributes to chemotherapeutic resistance in AML12 DNAJ-PKAc hepatocyte cell lines using the DNA damaging agent etoposide and the Bcl-2 inhibitor navitoclax. Wildtype AML12 cells were susceptible to each drug alone and in combination. In contrast, AML12 DNAJ-PKAc cells were moderately affected by etoposide, resistant to navitoclax, but markedly susceptible to the drug combination. These studies implicate BAG2 as a biomarker for advanced FLC and a chemotherapeutic resistance factor in DNAJ-PKAc signaling scaffolds.

GNB1 promotes hepatocellular carcinoma progression by targeting BAG2 to activate P38/MAPK signaling

G-proteins are intracellular partners of G-protein-coupled receptors. As a member of the G-protein family, GNB1 has been shown to play a pro-cancer role in lung cancer and breast cancer. However, the biological function and detailed mechanisms of GNB1 in hepatocellular carcinoma progression are unclear. In this study, we investigated the effects of GNB1 and its possible mechanism of action in hepatocellular carcinoma (HCC). The clinical significance of GNB1 was evaluated in a large cohort of HCC patients, showing that GNB1 was overexpressed in HCC compared to adjacent normal liver tissues, and increased GNB1 expression was associated with poor prognosis. We also demonstrated that GNB1 enhances cell proliferation, colony formation, and cell migration and invasion in vitro and promotes the epithelial-to-mesenchymal transition process in HCC cells. Tumor xenograft model assay confirmed the oncogenic role of GNB1 in tumorigenicity in nude mice. Activation of P38 signaling was found in the GNB1 overexpressed HCC cells. Further intervention of P38 confirmed it as an important signaling pathway for the oncogenic role of GNB1 in HCC. Moreover, co-immunoprecipitation followed by liquid chromatograph-mass spectrometry identified that GNB1 exerted oncogenic functions via the interaction of BAG2 and activated P38 signaling pathway. Together, our results reveal that GNB1 plays a pivotal oncogenic role in HCC by promoting the P38 pathway via cooperating with BAG2. GNB1 may serve as a prognostic biomarker for patients with HCC.

BAG2 Is a Novel Prognostic Biomarker and Promising Immunotherapy Target in Uveal Melanoma

BACKGROUND

The importance of BAG2 in malignancy is gradually being recognized, however, information on its role in uveal melanoma (UVM) is limited. We aimed to elucidate its function and potential mechanism of action in UVM.

METHODS

Using the Cancer Genome Atlas (TCGA) and GEO-related datasets, we analyzed the differential expression of BAG2 in tumors, combined with clinical information and methylation data to analyze the prognostic value of BAG2, differential methylation and its association with UVM metastasis. In addition, correlation analysis explored the immunological characteristics of BAG2 in UVM and the response to immunotherapy. Finally, a prognostic model of ferroptosis- related genes was constructed and validated.

RESULTS

BAG2 is significantly downregulated in multiple cancers including UVM. Prognostic analysis showed that BAG2 was an independent prognostic factor for UVM. Abnormal methylation of BAG2 may affect the metastasis of UVM and be significantly associated with poor prognosis. Immune analysis clarified that BAG2 was significantly associated with UVM immune cell infiltration and multiple immune checkpoints, and low expression of BAG2 was more beneficial in immunotherapy. In addition, the prognostic model of ferroptosis we constructed has good performance in predicting overall survival and metastasis-free survival of UVM.

CONCLUSIONS

BAG2 is an independent prognostic factor for UVM and may be a potential immune checkpoint for UVM.

Mining Potential Drug Targets for Osteoporosis Based on CeRNA Network

OBJECTIVE

To identify key pathological hub genes, micro RNAs (miRNAs), and circular RNAs (circRNAs) of osteoporosis (OP) and construct their ceRNA network in an effort to explore the potential biomarkers and drug targets for OP therapy.

METHODS

GSE7158, GSE201543, and GSE161361 microarray datasets were downloaded from Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified by comparing OP patients with healthy controls and hub genes were screened by machine learning algorithms. Target miRNAs and circRNAs were predicted by FunRich and circbank, then ceRNA network were constructed by Cytoscape. Pathways affecting OP were identified by functional enrichment analysis. The hub genes were verified by receiver operating characteristic (ROC) curve and real time quantitative PCR (RT-qPCR). Potential drug molecules related to OP were predicted by DSigDB database and molecular docking was analyzed by autodock vina software.

RESULTS

A total of 179 DEGs were identified. By combining three machine learning algorithms, BAG2, MME, SLC14A1, and TRIM44 were identified as hub genes. Three OP-associated target miRNAs and 362 target circRNAs were predicted to establish ceRNA network. The ROC curves showed that these four hub genes had good diagnostic performance and their differential expression was statistically significant in OP animal model. Benzo[a]pyrene was predicted which could successfully bind to protein receptors related to the hub genes and it was served as the potential drug molecules.

CONCLUSION

An mRNA-miRNA-circRNA network is reported, which provides new ideas for exploring the pathogenesis of OP. Benzo[a]pyrene, as potential drug molecules for OP, may provide guidance for the clinical treatment.

A Transformable Amphiphilic and Block Polymer-Dendron Conjugate for Enhanced Tumor Penetration and Retention with Cellular Homeostasis Perturbation via Membrane Flow

Efficient penetration and retention of therapeutic agents in tumor tissues can be realized through rational design of drug delivery systems. Herein, a polymer-dendron conjugate, POEGMA-b-p(GFLG-Dendron-Ppa) (GFLG-DP), is presented, which allows a cathepsin-B-triggered stealthy-to-sticky structural transformation. The compositions and ratios are optimized through dissipative particle dynamics simulations. GFLG-DP displays tumor-specific transformation and the consequently released dendron-Ppa is found to effectively accumulate on the tumor cell membrane. The interaction between the dendron-Ppa and the tumor cell membrane results in intracellular and intercellular transport via membrane flow, thus achieving efficient deep penetration and prolonged retention of therapeutic agents in the solid tumor tissues. Meanwhile, the interaction of dendron-Ppa with the endoplasmic reticulum disrupts cell homeostasis, making tumor cells more vulnerable and susceptible to photodynamic therapy. This platform represents a versatile approach to augmenting the tumor therapeutic efficacy of a nanomedicine via manipulation of its interactions with tumor membrane systems.

BAG Family Members as Mitophagy Regulators in Mammals

The BCL-2-associated athanogene (BAG) family is a multifunctional group of co-chaperones that are evolutionarily conserved from yeast to mammals. In addition to their common BAG domain, these proteins contain, in their sequences, many specific domains/motifs required for their various functions in cellular quality control, such as autophagy, apoptosis, and proteasomal degradation of misfolded proteins. The BAG family includes six members (BAG1 to BAG6). Recent studies reported their roles in autophagy and/or mitophagy through interaction with the autophagic machinery (LC3, Beclin 1, P62) or with the PINK1/Parkin signaling pathway. This review describes the mechanisms underlying BAG family member functions in autophagy and mitophagy and the consequences in physiopathology.

ASPER-29 suppresses the metastasis of pancreatic cancer cells by dual inhibition of cathepsin-L and cathepsin-S

Pancreatic cancer will be the second leading cause of cancer-related mortality worldwide due to its high rate of metastasis. Cathepsins (CATs) are effectors of invasive growth in various cancers. Currently, targeting CATs represents an attractive strategy for the treatment of highly metastatic cancers with high CATs activity, such as pancreatic cancer. To develop a stronger antimetastatic agent, ASPER-29, a novel inhibitor of CATs designed by using the asperphenamate derivative BBP as a lead compound, was synthesized, and its therapeutic potential in pancreatic cancer metastasis was investigated in this study. Molecular docking and enzyme inhibition assays proved that ASPER-29 can inhibit the activity of CAT-L and CAT-S by binding with these enzymes in classical action modes. Furthermore, ASPER-29 significantly inhibited the activity of CAT-L and CAT-S but had no effect on their expression in PANC-1 and BxPC-3 cells. The in vitro antimetastatic activities of ASPER-29 were examined by wound healing and Transwell chamber assays. We found that ASPER-29 inhibited the migration and invasion of PANC-1 and BxPC-3 cells in a concentration-dependent manner. Moreover, the in vivo antimetastatic effects of ASPER-29 were confirmed in a mouse xenotransplantation model. H&E staining and immunohistochemistry assays of Ki67 and CEACAM6 proved that ASPER-29 treatment significantly blocked the metastasis of pancreatic cancer cells to lung and liver tissues. Additionally, the activity of both CAT-L and CAT-S was markedly inhibited in the lung and liver tissues of ASPER-29-administered mice compared with the mice in the model group, suggesting that the metastasis-blocking effect of ASPER-29 should be mediated via inhibition of the activity of CAT-L and CAT-S in pancreatic cancer cells. Together, our results demonstrated that ASPER-29, as a novel inhibitor of CAT-L and CAT-S, possessed the evident ability to block the metastasis of pancreatic cancer cells.

Proteomic Signatures of Diffuse and Intestinal Subtypes of Gastric Cancer

Gastric cancer is a leading cause of death from cancer globally. Gastric cancer is classified into intestinal, diffuse and indeterminate subtypes based on histology according to the Laurén classification. The intestinal and diffuse subtypes, although different in histology, demographics and outcomes, are still treated in the same fashion. This study was designed to discover proteomic signatures of diffuse and intestinal subtypes. Mass spectrometry-based proteomics using tandem mass tags (TMT)-based multiplexed analysis was used to identify proteins in tumor tissues from patients with diffuse or intestinal gastric cancer with adjacent normal tissue control. A total of 7448 or 4846 proteins were identified from intestinal or diffuse subtype, respectively. This quantitative mass spectrometric analysis defined a proteomic signature of differential expression across the two subtypes, which included gremlin1 (GREM1), bcl-2-associated athanogene 2 (BAG2), olfactomedin 4 (OLFM4), thyroid hormone receptor interacting protein 6 (TRIP6) and melanoma-associated antigen 9 (MAGE-A9) proteins. Although GREM1, BAG2, OLFM4, TRIP6 and MAGE-A9 have all been previously implicated in tumor progression and metastasis, they have not been linked to intestinal or diffuse subtypes of gastric cancer. Using immunohistochemical labelling of a tissue microarray comprising of 124 cases of gastric cancer, we validated the proteomic signature obtained by mass spectrometry in the discovery cohort. Our findings should help investigate the pathogenesis of these gastric cancer subtypes and potentially lead to strategies for early diagnosis and treatment.

BAG2 mediates coelomocyte apoptosis in Vibrio splendidus challenged sea cucumber Apostichopus japonicus

MicroRNAs (miRNAs) are closely related to the occurrence, development, and immune response of diseases. BCL2-associated athanogene 2 (BAG2) is a member of the BAG family that functions in diverse cellular processes, including cell death, differentiation, and cell division. In this study, we cloned the cDNA full-length of sea cucumber (Apostichopus japonicus) BAG2 (AjBAG2) and confirmed it is an anti-apoptotic protein in vitro and in vivo during Vibrio splendidus infection. Moreover, we identified a perfect complementarity between miR-375 and the 3'-untranslated region (UTR) sequence of AjBAG2. The miR-375 expression decreased the luciferase activity dose-dependently when co-transfected with the AjBAG2 3'-UTR-luciferase reporter containing the miR-375 target site in epithelioma papulosum cyprini (EPC) cells. This inhibition was partially recovered by a miR-375 specific inhibitor. The mRNA and protein levels of AjBAG2 were opposite to that of coelomocytes in challenged sea cucumber when treated with miR-375 mimics or inhibitors. Additionally, miR-375 expression induced coelomocytes apoptosis and blocked the anti-apoptotic activity of AjBAG2. Our data demonstrated that AjBAG2 is an anti-apoptotic protein during V. splendidus infection and this function can be inhibited by miR-375 in sea cucumbers.

Gut Microbiota Dysbiosis Influences Metabolic Homeostasis in Spodoptera frugiperda

Insect gut microbiota plays important roles in acquiring nutrition, preventing pathogens infection, modulating immune responses, and communicating with environment. Gut microbiota can be affected by external factors such as foods and antibiotics. Spodoptera frugiperda (Lepidoptera: Noctuidae) is an important destructive pest of grain crops worldwide. The function of gut microbiota in S. frugiperda remains to be investigated. In this study, we fed S. frugiperda larvae with artificial diet with antibiotic mixture (penicillin, gentamicin, rifampicin, and streptomycin) to perturb gut microbiota, and then examined the effect of gut microbiota dysbiosis on S. frugiperda gene expression by RNA sequencing. Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria were the most dominant phyla in S. frugiperda. We found that the composition and diversity of gut bacterial community were changed in S. frugiperda after antibiotics treatment. Firmicutes was decreased, and abundance of Enterococcus and Weissella genera was dramatically reduced. Transcriptome analysis showed that 1,394 differentially expressed transcripts (DETs) were found between the control and antibiotics-treated group. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that antibiotics-induced dysbiosis affected many biological processes, such as energy production, metabolism, and the autophagy–lysosome signal pathway. Our results indicated that dysbiosis of gut microbiota by antibiotics exposure affects energy and metabolic homeostasis in S. frugiperda, which help better understand the role of gut microbiota in insects.

Transcriptome comparisons detect new genes associated with apoptosis of cattle and buffaloes preantral follicles

Background

To develop new breeding technology to improve the breeding ability of bovine, it is the development trend to find the main reason for the occurrence of atresia in these organisms. Transcriptomes of small (100–120 μm) and large (200–220 μm) preantral follicles from cattle and buffalo ovaries were evaluated in vivo and in vitro to understand the transcriptional modulation in preantral follicles that leads to the phenomenon of atresia.

Methods

The preantral follicles were checked as dead, damage, or live follicles in vivo and in vitro by using trypan blue then bisbenzimide and propidium iodine. Transcriptomes of small (100–120 μm) and large (200–220 μm) preantral follicles of cattle and buffalo were evaluated in vivo and in vitro by microarray and RT-PCR. Healthy preantral follicles were selected based on staining results, and then RNA was extracted from them.

Results

The viability percentage of preantral follicles in cattle was higher (26.7% and 20%) than buffalo (10%) in vivo and in vitro, respectively. According to the microarray data analysis for cattle preantral follicles, only eleven genes were detected corresponding to five upregulated and six downregulated in large size (200–220 μm) compared to small (100–120 μm) size preantral follicles, while in buffalo, 171 genes were detected (92 upregulated and 79 downregulated) in large size compared to small preantral follicle size. The results of RT-PCR of the selected genes (FASTKD1, BAG2, RHOB, AGTR2, MEF2C, BCL10, G2E3, TM2D1, IGF-I, IGFBP3, PRDX3, and TRIAP1) validated the microarray results. In conclusion, the data of gene expression showed significant differences between small and large sizes in both buffalo and cattle preantral follicles.

Conclusion

Apoptotic genes were upregulated in the large preantral follicle compared with the small preantral follicles. Moreover, the expression level of these apoptotic genes was significantly upregulated in buffalo than in the cattle. Most of these genes were significantly upregulated in the large buffalo preantral follicle compared with the small size. However, anti-apoptotic genes were upregulated in large cattle preantral follicle and downregulated in large buffalo preantral follicle.

Metastasis Risk Assessment Using BAG2 Expression by Cancer-Associated Fibroblast and Tumor Cells in Patients with Breast Cancer

Simple Summary

Cancer-associated fibroblasts (CAFs) promote tumor progression and play an important role in evading immune surveillance. The previous study showed that BAG2 could be elevated in cancer associated fibroblasts (CAFs). Here, we evaluated BAG2 expression of CAF and tumor cells and assessed metastasis risk in patients with breast cancer. We found that patients with either BAG2-high or BAG2(+) CAF had significantly worse distant metastasis-free survival than those with BAG2-double negative. Evaluation of BAG2 expression on both CAFs and tumor cells could be helpful to estimate the risk of metastasis in breast cancer.

Abstract

Few studies have examined the role of BAG2 in malignancies. We investigated the prognostic value of BAG2-expression in cancer-associated fibroblasts (CAFs) and tumor cells in predicting metastasis-free survival in patients with breast cancer. Tissue-microarray was constructed using human breast cancer tissues obtained by surgical resection between 1992 and 2015. BAG2 expression was evaluated by immunohistochemistry in CAFs or the tumor cells. BAG2 expression in the CAFs and cytoplasm of tumor cells was classified as positive and negative, and low and high, respectively. BAG2-CAF was evaluated in 310 patients and was positive in 67 (21.6%) patients. Kaplan–Meier plots showed that distant metastasis-free survival (DMFS) was lesser in patients with BAG2(+) CAF than in patients with BAG2(−) CAF (p = 0.039). Additionally, we classified the 310 patients into two groups: 109 in either BAG2-high or BAG2(+) CAF and 201 in BAG2-low and BAG2(−) CAF. DMFS was significantly reduced in patients with either BAG2-high or BAG2(+) CAF than in the patients of the other group (p = 0.005). Multivariable analysis demonstrated that DMFS was prolonged in patients with BAG2(−) CAF or BAG2-low. Evaluation of BAG2 expression on both CAFs and tumor cells could help in determining the risk of metastasis in breast cancer.

LC-MS/MS Proteomic Study of MCF-7 Cell Treated with Dox and Dox-Loaded Calcium Carbonate Nanoparticles Revealed Changes in Proteins Related to Glycolysis, Actin Signalling, and Energy Metabolism

Simple Summary

This work revealed that DOX-Ar-CC-NPs have the ability to promote cell death in MCF-7 cells, showing high potency in drug delivery. DOX-Ar-CC-NPs prompts cell death of MCF-7 cancer cells in vivo. LC-MS/MS Proteomic experemnt showed alteration on the expression of proteins linked to actine signaling, carbohydrate metabolisim.

Abstract

One of the most prevalent death causes among women worldwide is breast cancer. This study aimed to characterise and differentiate the proteomics profiles of breast cancer cell lines treated with Doxorubicin (DOX) and Doxorubicin-CaCO₃-nanoparticles (DOX-Ar-CC-NPs). This study determines the therapeutic potential of doxorubicin-loaded aragonite CaCO₃ nanoparticles using a Liquid Chromatography/Mass Spectrometry analysis. In total, 334 proteins were expressed in DOX-Ar-CC-NPs treated cells, while DOX treatment expressed only 54 proteins. Out of the 334 proteins expressed in DOX-CC-NPs treated cells, only 36 proteins showed changes in abundance, while in DOX treated cells, only 7 out of 54 proteins were differentially expressed. Most of the 30 identified proteins that are differentially expressed in DOX-CC-NPs treated cells are key enzymes that have an important role in the metabolism of carbohydrates as well as energy, including: pyruvate kinase, ATP synthase, enolase, glyceraldehyde-3-phosphate dehydrogenase, mitochondrial ADP/ATP carrier, and trypsin. Other identified proteins are structural proteins which included; Keratin, α- and β-tubulin, actin, and actinin. Additionally, one of the heat shock proteins was identified, which is Hsp90; other proteins include Annexins and Human epididymis protein 4. While the proteins identified in DOX-treated cells were tubulin alpha-1B chain and a beta chain, actin cytoplasmic 1, annexin A2, IF rod domain-containing protein, and 78 kDa glucose-regulated protein. Bioinformatics analysis revealed the predicted canonical pathways linking the signalling of the actin cytoskeleton, ILK, VEGF, BAG2, integrin and paxillin, as well as glycolysis. This research indicates that proteomic analysis is an effective technique for proteins expression associated with chemotherapy drugs on cancer tumours; this method provides the opportunity to identify treatment targets for MCF-7 cancer cells, and a liquid chromatography-mass spectrometry (LC-MS/MS) system allowed the detection of a larger number of proteins than 2-DE gel analysis, as well as proteins with maximum pIs and high molecular weight.

Identification of Adrenomedullin-Induced S-Nitrosylated Proteins in JEG-3 Placental Cells

Extravillous cytotrophoblast (EVCT) is responsible for trophoblast invasion, which is important during placentation. Dysregulation of the process leads to pregnancy complications. S-nitrosylation of proteins is associated with cell invasion in many cell types. Adrenomedullin (ADM), a polypeptide expressed abundantly in the first-trimester placentas, induces EVCT invasion by upregulation of protein S-nitrosylation. This study aimed to identify the S-nitrosylated proteins induced by ADM in the JEG-3 placental cells. By using affinity chromatography followed by mass spectrometric analysis, tubulin, enolase, eukaryotic translation initiation factor 4A1, actin, annexin II (ANX II), and glyceraldehyde 3-phosphate dehydrogenaseprotein-1 were found to be S-nitrosylated by ADM. In vitro treatment with ADM or S-Nitrosoglutathione (GSNO) significantly increased the ANX II surface expression, but not its total expression in the JEG-3 cells. Translocation of ANX II to cell surface has been reported to act as a cell surface receptor to plasmin, plasminogen, and tissue plasminogen activator (tPA), thereby stimulating cell invasion and migration. However, in this study, ADM-induced surface expression of ANX II in the JEG-3 cells was not associated with changes in the secretory and membrane-bound tPA activities. Future studies are required to understand the roles of surface expression of S-nitrosylated ANX II on trophoblast functions. To conclude, this study provided evidences that ADM regulated the nitric oxide signaling pathway and modulated trophoblast invasion.

MicroRNA-325 inhibits the proliferation and induces the apoptosis of T cell acute lymphoblastic leukemia cells in a BAG2-dependent manner

The inhibitory effect of microRNA (miR)-325 in multiple different types of cancer cell has been identified; however, its biological function in T cell acute lymphoblastic leukemia (T-ALL) remains unknown. Moreover, Bcl-2-associated athanogene (BAG)2 is highly expressed in a various types of tumors and is regarded as an anti-apoptotic gene. In the present study, the roles of miR-325 and BAG2 in a T-ALL cell line (Jurkat cells) were investigated. BAG2 and miR-325 expression levels in clinical blood samples from healthy donors and pediatric patients with T-ALL, as well as in T-ALL cell lines was detected using western blot analysis and/or reverse transcription-quantitative PCR. Dual-luciferase reporter gene assays and TargetScan were used to evaluate the interaction between BAG2 and miR-325. Small interfering RNA technology was applied to knockdown BAG2 expression in Jurkat cells. The effects of miR-325 mimic and BAG2 downregulation on the proliferation and apoptosis were assessed by an MTT assay, flow cytometry and western blot analysis. The results revealed that the expression of miR-325 was downregulated in blood samples from pediatric patients and in T-ALL cell lines, and its expression was lowest in Jurkat cells. The expression levels of BAG2 exhibited the opposite results. The knockdown of BAG2 markedly induced the apoptosis and inhibited the proliferation of Jurkat cells. In addition, the overexpression of miR-325 significantly inhibited the growth and promoted the apoptosis of Jurkat cells, with these effects being eliminated by BAG2 overexpression. In conclusion, the findings of the present study demonstrated that miR-325 directly targets the BAG2 gene and that the introduction of miR-325 can accelerate apoptosis and suppress the proliferation of Jurkat cells by silencing BAG2 expression.

Bcl-2 Associated Athanogene 2 (BAG2) is Associated With Progression and Prognosis of Hepatocellular Carcinoma: A Bioinformatics-Based Analysis

Background: Bcl-2 associated athanogene2 (BAG2) is reported to act as an oncogene or a tumor-suppressor in tumors in a context-dependent way; however, its function in hepatocellular carcinoma (HCC) remains unclear.

Methods: Immunohistochemistry (IHC) staining, cell counting kit-8 (CCK-8) assay, apoptotic assay, cell invasion assay and a set of bioinformatics tools were integrated to analyze the role of BAG2 in hepatocellular carcinoma.

Results: BAG2 was significantly up-regulated in HCC. Prognostic analysis indicated that HCC patients with high expression of BAG2 had significantly shorter overall survival, progression free survival and disease specific survival. Besides, silencing BAG2 in HCC cells impaired cell proliferation, facilitated apoptosis and repressed invasion of the cells. Bioinformatics analysis showed that BAG2 might regulate ribosome biogenesis in HCC.

Conclusion: This study revealed that the up-regulated BAG2 in HCC was associated with a worse prognosis and might favor the progression of the disease.

Identification of Overexpressed Genes in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a fatal tumor lacking effective therapies. The characterization of overexpressed genes could constitute a strategy for identifying drivers of tumor progression as targets for novel therapies. Thus, we performed an integrated gene-expression analysis on RNAseq data of 85 MPM patients from TCGA dataset and reference samples from the GEO. The gene list was further refined by using published studies, a functional enrichment analysis, and the correlation between expression and patients' overall survival. Three molecular signatures defined by 15 genes were detected. Seven genes were involved in cell adhesion and extracellular matrix organization, with the others in control of the mitotic cell division or apoptosis inhibition. Using Western blot analyses, we found that ADAMTS1, PODXL, CIT, KIF23, MAD2L1, TNNT1, and TRAF2 were overexpressed in a limited number of cell lines. On the other hand, interestingly, CTHRC1, E-selectin, SPARC, UHRF1, PRSS23, BAG2, and MDK were abundantly expressed in over 50% of the six MPM cell lines analyzed. Thus, these proteins are candidates as drivers for sustaining the tumorigenic process. More studies with small-molecule inhibitors or silencing RNAs are fully justified and need to be undertaken to better evaluate the cancer-driving role of the targets herewith identified.

Mitophagy-lysosomal pathway is involved in silver nanoparticle-induced apoptosis in A549 cells

With the increasing use of silver nanoparticles (AgNPs) in biological materials, the cytotoxicity caused by these particles has attracted much attention. However, the molecular mechanism underlying AgNP cytotoxicity remains unclear. In this study, we aimed to systematically investigate the toxicity induced by AgNP exposure to the lung adenocarcinoma A549 cell line at the subcellular and signaling pathway levels and elucidate the related molecular mechanism. The survival rate of cells exposed to AgNPs at 0, 20, 40, 80, and 160 μg/mL for 24 or 48 h decreased in a dose- and time-dependent manner. AgNPs induced autophagy and mitophagy, determined by the transmission electron microscopy investigation and upregulation of LC3 II/I, p62, PINK1, and Parkin expression levels. AgNP treatment induced lysosomal injury, including the decline of lysosomal membrane integrity and increase in cathepsin B level. The decreased in mitochondrial membrane potential, along with upregulation of cytochrome c, caspases 9 and 3, and BAX/BCL2, further suggested that mitochondrial injury were involved in AgNP-induced apoptosis. In addition, mitochondrial injury may further lead to excessive production of reactive oxygen species and oxidative/ antioxidant imbalance. The results suggested that AgNPs could regulate autophagy via mitochondrial and lysosome injury in A549 cells. The information of the molecular mechanism will provide an experimental basis for the safe application of nanomaterials.

PROBselect: accurate prediction of protein-binding residues from proteins sequences via dynamic predictor selection

Motivation

Knowledge of protein-binding residues (PBRs) improves our understanding of protein−protein interactions, contributes to the prediction of protein functions and facilitates protein−protein docking calculations. While many sequence-based predictors of PBRs were published, they offer modest levels of predictive performance and most of them cross-predict residues that interact with other partners. One unexplored option to improve the predictive quality is to design consensus predictors that combine results produced by multiple methods.

Results

We empirically investigate predictive performance of a representative set of nine predictors of PBRs. We report substantial differences in predictive quality when these methods are used to predict individual proteins, which contrast with the dataset-level benchmarks that are currently used to assess and compare these methods. Our analysis provides new insights for the cross-prediction concern, dissects complementarity between predictors and demonstrates that predictive performance of the top methods depends on unique characteristics of the input protein sequence. Using these insights, we developed PROBselect, first-of-its-kind consensus predictor of PBRs. Our design is based on the dynamic predictor selection at the protein level, where the selection relies on regression-based models that accurately estimate predictive performance of selected predictors directly from the sequence. Empirical assessment using a low-similarity test dataset shows that PROBselect provides significantly improved predictive quality when compared with the current predictors and conventional consensuses that combine residue-level predictions. Moreover, PROBselect informs the users about the expected predictive quality for the prediction generated from a given input protein.

Availability and implementation

PROBselect is available at http://bioinformatics.csu.edu.cn/PROBselect/home/index.

Supplementary information

Supplementary data are available at Bioinformatics online.

Lysosomal trafficking mediated by Arl8b and BORC promotes invasion of cancer cells that survive radiation

Enhanced invasiveness, a critical determinant of metastasis and poor prognosis, has been observed in cancer cells that survive cancer therapy, including radiotherapy. Here, we show that invasiveness in radiation-surviving cancer cells is associated with alterations in lysosomal exocytosis caused by the enhanced activation of Arl8b, a small GTPase that regulates lysosomal trafficking. The binding of Arl8b with its effector, SKIP, is increased after radiation through regulation of BORC-subunits. Knockdown of Arl8b or BORC-subunits decreases lysosomal exocytosis and the invasiveness of radiation-surviving cells. Notably, high expression of ARL8B and BORC-subunit genes is significantly correlated with poor prognosis in breast cancer patients. Sp1, an ATM-regulated transcription factor, is found to increase BORC-subunit genes expression after radiation. In vivo experiments show that ablation of Arl8b decreases IR-induced invasive tumor growth and distant metastasis. These findings suggest that BORC-Arl8b-mediated lysosomal trafficking is a target for improving radiotherapy by inhibiting invasive tumor growth and metastasis.

Co-delivery of IKBKE siRNA and cabazitaxel by hybrid nanocomplex inhibits invasiveness and growth of triple-negative breast cancer

IKBKE is an oncogene in triple-negative breast cancer (TNBC), and we demonstrate that IKBKE small interfering RNA (siRNA) inhibits the proliferation, migration, and invasion of TNBC cells. Despite the recent success of siRNA therapeutics targeting to the liver, there still remains a great challenge to deliver siRNAs to solid tumors. Here, we report a hybrid nanocomplex to co-deliver the IKBKE siRNA and cabazitaxel to TNBC to achieve an optimal antitumor effect. The nanocomplex is modified with hyaluronic acid to target CD44 on TNBC cells. The nanocomplex shows higher cellular uptake and better tumor penetration of the encapsulated cargos. The nanocomplex also exhibits high tumor accumulation and antitumor activity in an orthotopic TNBC mouse model. Encapsulation of cabazitaxel in the nanocomplex enhances the activity of the IKBKE siRNA. The hybrid nanocomplex provides a novel and versatile platform for combination therapies using siRNAs and chemotherapy.

Unraveling the Genomic-Epigenomic Interaction Landscape in Triple Negative and Non-Triple Negative Breast Cancer

Background: The recent surge of next generation sequencing of breast cancer genomes has enabled development of comprehensive catalogues of somatic mutations and expanded the molecular classification of subtypes of breast cancer. However, somatic mutations and gene expression data have not been leveraged and integrated with epigenomic data to unravel the genomic-epigenomic interaction landscape of triple negative breast cancer (TNBC) and non-triple negative breast cancer (non-TNBC). Methods: We performed integrative data analysis combining somatic mutation, epigenomic and gene expression data from The Cancer Genome Atlas (TCGA) to unravel the possible oncogenic interactions between genomic and epigenomic variation in TNBC and non-TNBC. We hypothesized that within breast cancers, there are differences in somatic mutation, DNA methylation and gene expression signatures between TNBC and non-TNBC. We further hypothesized that genomic and epigenomic alterations affect gene regulatory networks and signaling pathways driving the two types of breast cancer. Results: The investigation revealed somatic mutated, epigenomic and gene expression signatures unique to TNBC and non-TNBC and signatures distinguishing the two types of breast cancer. In addition, the investigation revealed molecular networks and signaling pathways enriched for somatic mutations and epigenomic changes unique to each type of breast cancer. The most significant pathways for TNBC were: retinal biosynthesis, BAG2, LXR/RXR, EIF2 and P2Y purigenic receptor signaling pathways. The most significant pathways for non-TNBC were: UVB-induced MAPK, PCP, Apelin endothelial, Endoplasmatic reticulum stress and mechanisms of viral exit from host signaling Pathways. Conclusion: The investigation revealed integrated genomic, epigenomic and gene expression signatures and signing pathways unique to TNBC and non-TNBC, and a gene signature distinguishing the two types of breast cancer. The study demonstrates that integrative analysis of multi-omics data is a powerful approach for unravelling the genomic-epigenomic interaction landscape in TNBC and non-TNBC.

SCRIBER: accurate and partner type-specific prediction of protein-binding residues from proteins sequences

Motivation

Accurate predictions of protein-binding residues (PBRs) enhances understanding of molecular-level rules governing protein–protein interactions, helps protein–protein docking and facilitates annotation of protein functions. Recent studies show that current sequence-based predictors of PBRs severely cross-predict residues that interact with other types of protein partners (e.g. RNA and DNA) as PBRs. Moreover, these methods are relatively slow, prohibiting genome-scale use.

Results

We propose a novel, accurate and fast sequence-based predictor of PBRs that minimizes the cross-predictions. Our SCRIBER (SeleCtive pRoteIn-Binding rEsidue pRedictor) method takes advantage of three innovations: comprehensive dataset that covers multiple types of binding residues, novel types of inputs that are relevant to the prediction of PBRs, and an architecture that is tailored to reduce the cross-predictions. The dataset includes complete protein chains and offers improved coverage of binding annotations that are transferred from multiple protein–protein complexes. We utilize innovative two-layer architecture where the first layer generates a prediction of protein-binding, RNA-binding, DNA-binding and small ligand-binding residues. The second layer re-predicts PBRs by reducing overlap between PBRs and the other types of binding residues produced in the first layer. Empirical tests on an independent test dataset reveal that SCRIBER significantly outperforms current predictors and that all three innovations contribute to its high predictive performance. SCRIBER reduces cross-predictions by between 41% and 69% and our conservative estimates show that it is at least 3 times faster. We provide putative PBRs produced by SCRIBER for the entire human proteome and use these results to hypothesize that about 14% of currently known human protein domains bind proteins.

Availability and implementation

SCRIBER webserver is available at http://biomine.cs.vcu.edu/servers/SCRIBER/.

Supplementary information

Supplementary data are available at Bioinformatics online.

LOXL1 confers antiapoptosis and promotes gliomagenesis through stabilizing BAG2

The lysyl oxidase (LOX) family is closely related to the progression of glioma. To ensure the clinical significance of LOX family in glioma, The Cancer Genome Atlas (TCGA) database was mined and the analysis indicated that higher LOXL1 expression was correlated with more malignant glioma progression. The functions of LOXL1 in promoting glioma cell survival and inhibiting apoptosis were studied by gain- and loss-of-function experiments in cells and animals. LOXL1 was found to exhibit antiapoptotic activity by interacting with multiple antiapoptosis modulators, especially BAG family molecular chaperone regulator 2 (BAG2). LOXL1-D515 interacted with BAG2-K186 through a hydrogen bond, and its lysyl oxidase activity prevented BAG2 degradation by competing with K186 ubiquitylation. Then, we discovered that LOXL1 expression was specifically upregulated through the VEGFR-Src-CEBPA axis. Clinically, the patients with higher LOXL1 levels in their blood had much more abundant BAG2 protein levels in glioma tissues. Conclusively, LOXL1 functions as an important mediator that increases the antiapoptotic capacity of tumor cells, and approaches targeting LOXL1 represent a potential strategy for treating glioma. In addition, blood LOXL1 levels can be used as a biomarker to monitor glioma progression.

SWATH-MS Analysis of FFPE Tissues Identifies Stathmin as a Potential Marker of Endometrial Cancer in Patients Exposed to Tamoxifen

A specific form of endometrial cancer (EC) can develop in breast cancer patients previously treated with tamoxifen (ET), an antagonist of estrogen receptor (ER) that inhibits proliferation of ER positive breast cancer. ET tumors have a different phenotype than endometrial tumors, which typically develop de novo without previous exposure to tamoxifen (EN). Here we aimed to identify specific protein markers that could serve as specific molecular targets in either phenotype. A set of total 45 formalin-fixed paraffin-embedded (FFPE) endometrial tumor tissues and adjacent myometrium tissue samples were analyzed using LC-MS/MS in SWATH-MS mode. We found that calcyphosin (CAPS) levels were elevated in EN tumors compared to ET tumors. The higher CAPS level in EC tissue invading to myometrium supports its relationship to EC aggressiveness. Further, stathmin (STMN1) levels were found significantly elevated in ET versus EN tumors and significantly associated with patient survival. This finding connects elevated levels of this cell cycle regulating, proliferation-associated protein with tamoxifen exposure. In summary, using SWATH-MS we show that CAPS and STMN1 should be recognized as clinicopathologically different EC markers of which STMN1 is specifically connected with a previous tamoxifen exposition.

Possible Insecticidal Mechanism of Cry41-Related Toxin against Myzus persicae by Enhancing Cathepsin B Activity

Cry toxins produced by Bacillus thuringiensis are well known for their high insecticidal activities against Lepidoptera, Diptera, and Coleoptera; however, their activities against Aphididae are very low. Recently, it has been reported that a Cry41-related toxin exhibited moderate activity against the aphid Myzus persicae, and thus, it is highly desirable to uncover its unique mechanism. In this paper, we report that Cathepsin B, calcium-transporting ATPase, and symbiotic bacterial-associated protein ATP-dependent-6-phosphofructokinase were pulled down from the homogenate of M. persicae as unique proteins that possibly bound to Cry41-related toxin. Cathepsin B has been reported to cleave and inactivate antiapoptotic proteins and plays a role in caspase-initiated apoptotic cascades. In this study, Cathepsin B was expressed in Escherichia coli and purified, and in vitro interaction between recombinant Cathepsin B and Cry41-related toxin was demonstrated. Interestingly, we found that addition of Cry41-related toxin obviously enhanced Cathepsin B activity. We propose a model for the mechanism of Cry41-related toxin as follows: Cry41-related toxin enters the aphid cells and enhances Cathepsin B activity, resulting in acceleration of apoptosis of aphid cells.

Tumor-Draining Lymph Secretome En Route to the Regional Lymph Node in Breast Cancer Metastasis

BACKGROUND

During metastasis, tumor cells metastasize from primary tumors to distant organs via the circulatory and the lymphatic systems. There is a plethora of information about metastasis through the circulatory system, however not much information is available about the tumor cells dissemination through the lymphatic system or the lymphatic microenvironment that aids in this process in breast cancer metastasis.

PURPOSE

The study designed to examine the tumor-derived secretome in lymph before reaching the draining lymph nodes.

METHODS

Using a microsurgical technique, we have collected the lymph in transit from the primary tumor en route to the regional lymph node in animals with metastatic and non-metastatic mammary carcinoma and healthy controls. The lymph samples were subjected to LC-MS/MS analysis, bioinformatics, and pathway analysis.

RESULTS

The metastatic tumor-draining lymph before its entry into the closest regional lymph node contain 26 proteins with >175-folds in abundance compared to lymph from non-metastatic tumor-bearing animals. Among these proteins were biliverdin reductase B, heat shock protein, coagulation factor XIII, lymphocytes cytosol protein 1, and aldose reductase. These proteins were not identified in the lymph from healthy animals. Pathways analysis revealed that cadherin-mediated endocytosis, acute phase response, junction signaling, gap junction, VEGF singling, and PI3K/AKT singling pathways are overrepresented in the lymph from metastatic tumor-bearing compared to the lymph from non-metastatic tumor-bearing animals. Among the significantly up-regulated proteins in the lymph from metastatic tumor-bearing animals were proteins that identified in exosomes include heat shock protein, enolase 1 alpha, S100, and biliverdin reductase B. One of the proteins significantly down-regulated in lymph from animals with metastasis is Kininogen, a known metastasis inhibitor protein.

CONCLUSION

Proteins and exosomal proteins in lymph draining a metastatic tumor are different from those in lymph draining non-metastatic tumors, and these proteins involved in pathways that regulate tumor cells migration and invasion.

BAG2 Promotes Proliferation and Metastasis of Gastric Cancer via ERK1/2 Signaling and Partially Regulated by miR186

Bcl2-associated athanogene (BAG)2 as a co-chaperone has been demonstrated to be involved in tumor growth and metastasis, but its biological function in gastric cancer remains unknown. Here, we reported that BAG2 was highly expressed in gastric cancer cell lines and tissues, indicating poor prognosis. High expression of BAG2 was significantly associated with T stage and differentiation level of gastric cancer (P < 0.001). Functional experiments revealed that BAG2 knockdown in gastric cancer cells inhibited the proliferation, invasion and migration of cells through AKT/mTOR and extracellular regulated kinase (ERK) pathways. Proteomic analysis identified that BAG2 may be involved in the regulation of mitogen-activated protein kinase (MAPK) pathway. In addition, immunoprecipitation showed that BAG2 could bind to ERK1/2. Luciferase reporter assay and Western blot verified that BAG2 was down-regulated by miR186. Taken together, our findings may reveal the basic function of BAG2 and uncover a potential therapeutic target for gastric cancer.

A BAG's life: Every connection matters in cancer

The members of the BCL-2 associated athanogene (BAG) family participate in the regulation of a variety of interrelated physiological processes, such as autophagy, apoptosis, and protein homeostasis. Under normal circumstances, the six BAG members described in mammals (BAG1-6) principally assist the 70 kDa heat-shock protein (HSP70) in protein folding; however, their role as oncogenes is becoming increasingly evident. Deregulation of the BAG multigene family has been associated with cell transformation, tumor recurrence, and drug resistance. In addition to BAG overexpression, BAG members are also involved in many oncogenic protein-protein interactions (PPIs). As such, either the inhibition of overloading BAGs or of specific BAG-client protein interactions could have paramount therapeutic value. In this review, we will examine the role of each BAG family member in different malignancies, focusing on their modular structure, which enables interaction with a variety of proteins to exert their pro-tumorigenic role. Lastly, critical remarks on the unmet needs for proposing effective BAG inhibitors will be pointed out.

Comparative Proteomic Analysis Reveals Immune Competence in Hemolymph of Bombyx mori Pupa Parasitized by Silkworm Maggot Exorista sorbillans

The silkworm maggot, Exoristasorbillans, is a well-known larval endoparasitoid of the silkworm Bombyxmori that causes considerable damage to the silkworm cocoon crop. To gain insights into the response mechanism of the silkworm at the protein level, we applied a comparative proteomic approach to investigate proteomic differences in the hemolymph of the female silkworm pupae parasitized by E. sorbillans. In total, 50 differentially expressed proteins (DEPs) were successfully identified, of which 36 proteins were upregulated and 14 proteins were downregulated in response to parasitoid infection. These proteins are mainly involved in disease, energy metabolism, signaling pathways, and amino acid metabolism. Eight innate immune proteins were distinctly upregulated to resist maggot parasitism. Apoptosis-related proteins of cathepsin B and 14-3-3 zeta were significantly downregulated in E. sorbillans-parasitized silkworm pupae; their downregulation induces apoptosis. Quantitative PCR was used to further verify gene transcription of five DEPs, and the results are consistent at the transcriptional and proteomic levels. This was the first report on identification of possible proteins from the E. bombycis-parasitized silkworms at the late stage of parasitism, which contributes to furthering our understanding of the response mechanism of silkworms to parasitism and dipteran parasitoid biology.

BAG2 ameliorates endoplasmic reticulum stress-induced cell apoptosis in Mycobacterium tuberculosis-infected macrophages through selective autophagy

BAG2 (BCL2 associated athanogene 2) is associated with cell fate determination in response to various pathological conditions. However, the effects of BAG2 on M. tuberculosis-induced endoplasmic reticulum (ER) stress remain elusive. Herein, we report that M. tuberculosis infection of macrophages triggered ER stress and downregulated BAG2 expression. Overexpression of BAG2 enhanced autophagic flux and activated macroautophagy/autophagy targeted to the ER (reticulophagy). In addition, through increasingly localizing SQSTM1 to the ER in BAG2-overexpressing macrophages, we found that the autophagy receptor protein SQSTM1/p62 (sequestosome 1) is associated with the BAG2-induced reticulophagy. Our data also confirmed that BAG2 could render cells resistant to M. tuberculosis-induced cellular damage, and the anti-apoptotic effects of BAG2 in M. tuberculosis-treated macrophages were partially abolished by the autophagic flux inhibitor bafilomycin A₁. Furthermore, the dissociation of BECN1 and BCL2 mediated by activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) was responsible for BAG2-activated autophagy. In addition, XBP1 downstream of the ERN1/IRE1 signaling pathway was bound to the Bag2 promoter region and transcriptionally inhibited BAG2 expression. Collectively, these results indicated that BAG2 has anti-apoptotic effects on M. tuberculosis-induced ER stress, which is dependent on the promotion of autophagic flux and the induction of selective autophagy. We revealed a potential host defense mechanism that links BAG2 to ER stress and autophagy during M. tuberculosis infection.

ABBREVIATIONS

ATF6: activating transcription factor 6; BECN1: beclin 1; Baf A1: bafilomycin A₁; CASP3: caspase 3; DDIT3/CHOP/GADD153: DNA damage inducible transcript 3; DAPI: 4',6-diamidino-2-phenylindole; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 3; ER: endoplasmic reticulum; ERN1/IRE1: endoplasmic reticulum to nucleus signaling 1; HSPA5/GRP78/BiP: heat shock protein 5; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MAPK/ERK: mitogen-activated protein kinase; SQSTM1/p62: sequestosome 1; UPR: unfolded protein response; XBP1: x-box binding protein 1.

'Patchiness' and basic cancer research: unravelling the proteases

The recent developments in Cathepsin protease research have unveiled a number of key observations which are fundamental to further our understanding of normal cellular homeostasis and disease. By far, the most interesting and promising area of Cathepsin biology stems from how these proteins are linked to the fate of living cells through the phenomenon of Lysosomal Leakage and Lysosomal Membrane Permeabilisation. While extracellular Cathepsins are generally believed to be of central importance in tumour progression, through their ability to modulate the architecture of the Extracellular Matrix, intracellular Cathepsins have been established as being of extreme significance in mediating cell death through Apoptosis. With these two juxtaposed key research areas in mind, the focus of this review highlights recent advancements in how this fast-paced area of Cathepsin research has recently evolved in the context of their mechanistic regulation in cancer research. Abbreviations : ECM, Extracellular Matrix; MMP, Matrix Metalloproteases; LL, Lysosomal Leakage; LMP, Lysosomal Membrane Permeabilisation; LMA, Lysosomorphic Agents; BC, Breast Cancer; ASM, Acid Sphingomyelinase; TNF-α, Tumor Necrosis Factor-alpha; LAMP, Lysosomal Associated membrane Protein; PCD, Programmed Cell Death; PDAC, Pancreatic Ductal Adenocarcinoma; ROS, Reactive Oxygen Species; aa, amino acids.

Over-expression of Bcl2-associated athanogene 2 in oral cancer promotes cellular proliferation and is associated with poor prognosis

OBJECTIVE

The aim of the present study was to state the role of BAG2 in oral squamous cell carcinomas (OSCC).

DESIGN

Expression data of BAG2 in OSCC tissues were extracted from Oncomine and TCGA database. Expression levels of BAG2 mRNA and protein were examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot assay. The Kaplan-Meier method was conducted to evaluate the overall survival of OSCC patients. Small interfering RNAs (siRNAs) strategy was used to confirm the effect of BAG2 expression on proliferative, invasive, migrated capacities of OSCC cells by Cell Counting kit-8 (CCK-8), colon formation assay, wound healing and transwell assay.

RESULTS

Our results showed that BAG2 expression was up-regulated in oral squamous cell carcinomas tissues. Compared with OSCC patients with low BAG2 expression, poorer overall survival rate was found in OSCC patients with high BAG2 expression. Furthermore, proliferation, invasion and migration of HO-1-N-1 cells were significantly inhibited because of the knockdown of BAG2. Transfection of si-BAG2 has no impacts on proliferation in HNOEC cells. Inhibition of BAG2 downregulated the expression of relevant proteins, such as proliferating cell nuclear antigen (PCNA), c-Myc, matrix metalloproteinase-2 (MMP-2) and Vimentin. Additionally, the expression levels of the important protein phosphorylation (p-ERK1/2 and p-MEK) in mitogen-activated protein kinase (MAPK) pathway were reduced in HO-1-N-1 cells transfected with si-BAG2.

CONCLUSIONS

High-regulated BAG2 is related to poor prognosis and could promote proliferation, invasion and migration of OSCC cells by activating the MAPK signaling pathway. Thus, BAG2 may be a potential target for OSCC therapy.

BAG2 Overexpression Correlates with Growth and Poor Prognosis of Esophageal Squamous Cell Carcinoma

Previous studies have suggested that Bcl2-associated athanogene 2 (BAG2) serves as a crucial regulator for tumorigenesis in multiple tumors. However, little is known about the effect of BAG2 on esophageal squamous cell carcinoma (ESCC). This study focused on investigating whether BAG2 functions as a cancer-promoting gene in ESCC. In this work, gene expression data and clinical information from the NCBI Gene Expression Omnibus (GEO), Oncomine and The Cancer Genome Atlas (TCGA) were collected and analyzed. Expression of BAG2 in ESCC was determined using quantitative reverse transcription polymerase chain reaction (qRT-PCR). BAG2 was knocked down using small interference RNA (si-RNA) approach. Cell proliferation, migration and invasion were assessed by Cell Counting Kit-8 (CCK-8) and transwell assays. Molecular mechanism was detected by western blotting assay. The expression of BAG2 both in ESCC tissues and cells was upregulated and overexpression was associated with worsened prognosis. BAG2 silencing inhibited ESCC cell proliferation, migration and invasion, which was regulated by the phosphatidylinositol-3-kinase (PI3K)/ protein kinase B (AKT) signaling pathway. These results reveal contributions of BAG2 as a predictor and potential therapeutic target in ESCC.

Patulin Induces Autophagy-Dependent Apoptosis through Lysosomal-Mitochondrial Axis and Impaired Mitophagy in HepG2 Cells

Patulin (PAT) is a compound produced by fungi including those of the Aspergillus, Penicillium, and Byssochlamys species. PAT has been linked with negative outcomes in certain microorganisms and animal species, but how it causes hepatotoxicity is poorly understood. In this study, we determined that, by treating HepG2 cells using PAT, these cells could be induced to rapidly undergo autophagy, and this was followed within 12 h of treatment by lysosomal membrane permeabilization (LMP) and cathepsin B release. We were able to block these outcomes if cells were treated with 3-methyladenine (3MA), an inhibitor of autophagy, prior to PAT treatment. Moreover, PAT-induced collapse of mitochondrial membrane potential (ΔΨm) depended both on cathepsin B and autophagy. 3MA was further able to reduce the induction of apoptosis in response to PAT, suggesting that autophagy is a driving mechanism for this apoptotic induction. Inhibiting cathepsin B using CA-074 Me further reduced PAT-induced collapses of ΔΨm, mitochondiral cytochrome c release, and apoptosis. We also found that extended treatment of HepG2 cells using PAT over a period of 24 h led to the impairment of mitophagy such that morphologically swollen mitochondria accumulated within cells, and PINK1 failed to colocalize with LC3. Together these data reveal that PAT treatment can promote the induction of apoptosis in HepG2 cells in a manner dependent upon autophagy that progresses via the lysosomal-mitochondrial axis. This study thereby affords new insights into the mechanisms by which PAT drives hepatotoxicity.

Cathepsin B inhibition ameliorates the non-alcoholic steatohepatitis through suppressing caspase-1 activation

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most common chronic liver disease. NLRP3 inflammasome activation has been widely studied in the pathogenesis of NAFLD. Cathepsin B (CTSB) is a ubiquitous cysteine cathepsin, and the role of CTSB in the progression and development of NAFLD has received extensive concern. However, the exact roles of CTSB in the NAFLD development and NLRP3 inflammasome activation are yet to be evaluated. In the present study, we used methionine choline-deficient (MCD) diet to establish mice NASH model. CTSB inhibitor (CA-074) was used to suppress the expression of CSTB. Expressions of CTSB and caspase-1 were evaluated by immunohistochemical staining. Serum IL-1β and IL-18 levels were also determined. Palmitic acid was used to stimulate Kupffer cells (KCs), and protein expressions of CTSB, NLRP3, ASC (apoptosis-associated speck-like protein containing CARD), and caspase-1 in KCs were detected. The levels of IL-1β and IL-18 in the supernatant of KCs were evaluated by enzyme-linked immunosorbent assay (ELISA). Our results showed that CTSB inhibition improved the liver function and reduced hepatic inflammation and ballooning, and the levels of pro-inflammatory cytokines IL-1β and IL-18 were decreased. The expressions of CTSB and caspase-1 in liver tissues were increased in the NASH group. In in vitro experiments, PA stimulation could increase the expressions of CTSB and NLRP3 inflammasome in KCs, and CTSB inhibition downregulated the expression of NLRP3 inflammasome in KCs, when challenged by PA. Moreover, CTSB inhibition effectively suppressed the expression and activity of caspase-1 and subsequently secretions of IL-1β and IL-18. Collectively, these results suggest that CTSB inhibition limits NLRP3 inflammasome-dependent NASH formation through regulating the expression and activity of caspase-1, thus providing a novel anti-inflammatory signal pathway for the therapy of NAFLD.