Gut commensal Parabacteroides distasonis alleviates inflammatory arthritis.

OBJECTIVE: Gut microbiota dysbiosis is closely linked to the pathogenesis of rheumatoid arthritis (RA). We aimed to identify potential probiotic gut microbes that can ameliorate the development of RA. DESIGN: Microbiota profiling in patients with RA and healthy individuals was investigated via 16S rDNA bacterial gene sequencing and shotgun metagenomics. Collagen-induced arthritic mice and TNF-α transgenic mice were used to evaluate the roles of the gut commensal Parabacteroides distasonis in RA. The effects of P. distasonis-derived microbial metabolites on the differentiation of CD4+ T cells and macrophage polarisation were also investigated. RESULTS: The relative abundance of P. distasonis in new-onset patients with RA and patients with RA with history of the disease was downregulated and this decrease was negatively correlated with Disease Activity Score-28 (DAS28). Oral treatment of arthritic mice with live P. distasonis (LPD) considerably ameliorated RA pathogenesis. LPD-derived lithocholic acid (LCA), deoxycholic acid (DCA), isolithocholic acid (isoLCA) and 3-oxolithocholic acid (3-oxoLCA) had similar and synergistic effects on the treatment of RA. In addition to directly inhibiting the differentiation of Th17 cells, 3-oxoLCA and isoLCA were identified as TGR5 agonists that promoted the M2 polarisation of macrophages. A specific synthetic inhibitor of bile salt hydrolase attenuated the antiarthritic effects of LPD by reducing the production of these four bile acids. The natural product ginsenoside Rg2 exhibited its anti-RA effects by promoting the growth of P. distasonis. CONCLUSIONS: P. distasonis and ginsenoside Rg2 might represent probiotic and prebiotic agents in the treatment of RA.

Triptolide attenuates inhibition of ankylosing spondylitis-derived mesenchymal stem cells on the osteoclastogenesis through modulating exosomal transfer of circ-0110634.

Background: Ankylosing spondylitis (AS) is featured by chronic inflammation of the sacroiliac joints and spine as well as pathological new bone formation. Osteoclastogenesis is a critical part in the development of bone formation. Circular RNAs (circRNAs) are recent research hotspot in the RNA field while rarely reported in osteoclastogenesis. Methods: AS mesenchymal stem cells (ASMSCs) and healthy donor mesenchymal stem cells (HDMSCs) were co-cultured with peripheral blood mononuclear cells (PBMCs). RT-qPCR was applied to detect the expression level of circ-0110634 in different exosomes. TRAP staining and TRAP activity detection were performed to identify the effect of circ-0110634 overexpression on osteoclastogenesis. Bioinformatics analysis and mechanism investigation were conducted to explore the downstream molecular mechanism of circ-0110634. Results: The effect of ASMSCs on PBMCs osteoclastogenesis is weaker than that of HDMSCs. Circ-0110634 had higher expression in ASMSCs exosomes than HDMSCs exosomes. Circ-0110634 overexpression suppressed the osteoclastogenesis. Circ-0110634 bound to both TNF receptor associated factor 2 (TRAF2) and tumor necrosis factor receptor II (TNFRII). Circ-0110634 also accelerated the dimerization of TRAF2 to induce TRAF2 ubiquitination and degradation. Circ-0110634 repressed the interplay between TRAF2 and TNFRII to inactivate the nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPK) pathways. Triptolide promoted the osteoclastogenesis of ASMSCs exosomes-treated PBMCs via decreasing the exosomal transference of circ-0110634 in a dose-dependent manner. Consistently, triptolide treatment stimulated osteoclastogenesis to alleviate the arthritis of DBA/1 mice through suppressing circ-0110634. Conclusion: Our study confirmed that triptolide targets circ-0110634 to ease the burden of AS patients. The Translational potential of this article: This study suggests triptolide targets circ-0110634 to regulate osteoclastogenesis, which provides a novel potential target in triptolide treatment for AS patients.

TMT-based quantitative proteomics analysis and potential serum protein biomarkers for systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) was not only a typical systemic autoimmune disease, but also one of the most challenging heterogeneous diseases for physicians. Currently, the pathogenesis of SLE was unclear, and there were no accurate, universal or easy-to-use diagnostic criteria for assessing SLE activity and predicting SLE severity. Proteins were direct effectors of biological mechanisms, and were closer to clinical phenotypes than the other discovered biomarkers. Moreover, proteins were widely used as biomarkers for clinical diagnosis and mechanism research of many diseases. Herein, we compared the proteins profiles of healthy individuals (HCs) and SLE patients to reveal the pathogenesis and provide evidence for diagnosis and management of persons with SLE. Serum samples were collected from 28 SLE patients and 30 HCs. Tandem mass tag (TMT)-based quantitative proteomics method was used to identify, screen and detect differentially expressed proteins (DEPs) in the collected serum samples. A total of 744 proteins were identified, and 84 of them were considered as DEPs with 71 upregulated and 13 downregulated. Bioinformatics analysis suggested that these DEPs were mainly involved in many biological processes, including immune response, signal transduction, inflammatory response, proteolysis, innate immune response and apoptosis, which were closely related to the pathogenesis of SLE. After comprehensive analysis, serum amyloid A1 (SAA1) and endothelin (CD248) were identified as specific biomarkers for the diagnosis of SLE, and were confirmed by subsequent enzyme-linked immunosorbent assays (ELISA), indicating a high reliability of TMT-based quantitative proteomics results. Areas under the ROC curve (AUC) results confirmed that SAA1 and CD248 combination as early immune diagnosis biomarkers of SLE presented excellent sensitivity and specificity.

Untargeted lipidomics reveals specific lipid abnormalities in systemic lupus erythematosus.

OBJECTIVES: To identify potential lipid biomarkers by studying changes in the blood lipid profile of patients with systemic lupus erythematosus (SLE) using lipidomics. METHODS: Serum samples were collected from 115 SLE patients and 115 age- and sex-matched healthy controls (HCs). Lipid profiles were assessed using ultrahigh-performance liquid chromatography coupled with Q Exactive spectrometry, and possible lipid biomarkers were screened and evaluated by univariate and multivariate analyses. RESULTS: Metabolic phenotypes related to SLE disease activity index (SLEDAI) scores were detected in the serum of SLE patients, and these phenotypes indicated the activity of the disease. Alterations in energy metabolism, fatty acid metabolism and other pathways were observed in patients with SLE. Phosphatidylethanolamine (16:0/18:2), lysophosphatidylethanolamine (18:0), and acylcarnitine (11:0) can be used as biomarkers for the clinical diagnosis of SLE, and receiver operating characteristic (ROC) analysis indicated their effectiveness in diagnosing this disease. CONCLUSIONS: Our study identified serum biomarkers related to disease activity in patients with SLE, providing a basis for its clinical diagnosis.

Serum lipidomics reveals distinct metabolic profiles for asymptomatic hyperuricemic and gout patients.

OBJECTIVES: This study aimed to characterize the systemic lipid profile of patients with asymptomatic hyperuricemia (HUA) and gout using lipidomics, and to find potential underlying pathological mechanisms therefrom. METHODS: Sera were collected from Affiliated Hospital of Nanjing University of Chinese Medicine as centre 1 (discovery and internal validation sets) and Suzhou Hospital of Traditional Chinese Medicine as centre 2 (external validation set), including 88 normal subjects, 157 HUA and 183 gout patients. Lipidomics was performed by ultra high performance liquid chromatography plus Q-Exactive mass spectrometry (UHPLC-Q Exactive MS). Differential metabolites were identifed by both variable importance in the projection ≥1 in orthogonal partial least-squares discriminant analysis mode and false discovery rate adjusted P ≤ 0.05. Biomarkers were found by logistic regression and receiver operating characteristic (ROC) analysis. RESULTS: In the discovery set, a total of 245 and 150 metabolites, respectively, were found for normal subjects vs HUA and normal subjects vs gout. The disturbed metabolites included diacylglycerol, triacylglycerol (TAG), phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, etc. We also found 116 differential metabolites for HUA vs gout. Among them, the biomarker panel of TAG 18:1-20:0-22:1 and TAG 14:0-16:0-16:1 could differentiate well between HUA and gout. The area under the receiver operating characteristic ROC curve was 0.8288, the sensitivity was 82% and the specificity was 78%, at a 95% CI 0.747, 0.9106. In the internal validation set, the predictive accuracy of TAG 18:1-20:0-22:1 and TAG 14:0-16:0-16:1 panel for differentiation of HUA and gout reached 74.38%, while it was 84.03% in external validation set. CONCLUSION: We identified serum biomarkers panel that have the potential to predict and diagnose HUA and gout patients.

Untargeted serum metabolomics and potential biomarkers for Sjögren's syndrome.

OBJECTIVES: At present, the pathogenesis of Sjögren's syndrome (SS) remains unclear. This research aimed to identify differential metabolites that contribute to SS diagnosis and discover the disturbed metabolic pathways. METHODS: Recent advances in mass spectrometry have allowed the identification of hundreds of unique metabolic signatures and the exploration of altered metabolite profiles in disease. In this study, 505 candidates including healthy controls (HCs) and SS patients were recruited and the serum samples were collected. A non-targeted gas chromatography-mass spectrometry (GC-MS) serum metabolomics method was used to explore the changes in serum metabolites. RESULTS: We found SS patients and HCs can be distinguished by 21 significant metabolites. The levels of alanine, tryptophan, glycolic acid, pelargonic acid, cis-1-2-dihydro-1-2-naphthalenediol, diglycerol, capric acid, turanose, behenic acid, dehydroabietic acid, stearic acid, linoleic acid, heptadecanoic acid, valine, and lactic acid were increased in serum samples from SS patients, whereas levels of catechol, anabasine, 3-6-anhydro-D-galactose, beta-gentiobiose, 2-ketoisocaproic acid and ethanolamine were decreased. The significantly changed pathways included the following: Linoleic acid metabolism; unsaturated fatty acid biosynthesis; aminoacyl-tRNA biosynthesis; valine, leucine, and isoleucine biosynthesis; glycerolipid metabolism; selenocompound metabolism; galactose metabolism; alanine, aspartate and glutamate metabolism; glyoxylate and dicarboxylate metabolism; glycerophospholipid metabolism; and valine, leucine and isoleucine degradation. CONCLUSIONS: These findings enhance the informative capacity of biochemical analyses through the identification of serum biomarkers and the analysis of metabolic pathways and contribute to an improved understanding of the pathogenesis of SS.

Triptolide reduces salivary gland damage in a non-obese diabetic mice model of Sjögren's syndrome via JAK/STAT and NF-κB signaling pathways.

Triptolide (TP) has anti-inflammatory and immunosuppressive effects. However, the effect of triptolide on Sjögren's syndrome (SS) is rarely reported. In this paper, we studied the effects of triptolide on non-obese diabetes mice model of SS. In this study, salivary flow rate was measured every two weeks, and autoantibodies levels in the serum were detected. Salivary gland index and spleen index were detected, pathological changes of salivary gland were detected by hematoxylin-eosin staining, inflammatory factors were detected by enzyme linked immunosorbent assay, lymphocytes were detected by flow cytometry, proliferation of T cells and B cells were detected, and related proteins were detected by Western blot. Triptolide increased salivary flow rate and salivary gland index, and decreased spleen gland index. Moreover, triptolide reduced the infiltration of lymphocytes to salivary glands, decreased the level of autoantibodies in serum, and reduced the inflammatory factors in salivary glands and IFN-γ induced salivary gland epithelial cells. Further, triptolide inhibited activator of JAK/STAT pathway and NF-κB pathway. In conclusion, triptolide could inhibit the infiltration of lymphocytes and the expression of inflammatory factors through JAK/STAT pathway and NF-κB pathway. Thus, triptolide may be used as a potential drug to treat SS.

Untargeted lipidomics reveals specific lipid abnormalities in Sjögren's syndrome.

OBJECTIVE: The relationship between serum lipid variations in SS and healthy controls was investigated to identify potential predictive lipid biomarkers. METHODS: Serum samples from 230 SS patients and 240 healthy controls were collected. The samples were analysed by ultrahigh-performance liquid chromatography coupled with Q Exactive™ spectrometry. Potential lipid biomarkers were screened through orthogonal projection to latent structures discriminant analysis and further evaluated by receiver operating characteristic analysis. RESULTS: A panel of three metabolites [phosphatidylcholine (18:0/22:5), triglyceride (16:0/18:0/18:1) and acylcarnitine (12:0)] was identified as a specific biomarker of SS. The receiver operating characteristic analysis showed that the panel had a sensitivity of 84.3% with a specificity of 74.8% in discriminating patients with SS from healthy controls. CONCLUSION: Our approach successfully identified serum biomarkers associated with SS patients. The potential lipid biomarkers indicated that SS metabolic disturbance might be associated with oxidized lipids, fatty acid oxidation and energy metabolism.

Fibrinogen-Like Protein 1 Is a Novel Biomarker for Predicting Disease Activity and Prognosis of Rheumatoid Arthritis.

Rheumatoid arthritis (RA), afflicting over 1% of the population, is an inflammatory joint disease leading to cartilage damage and ultimately impaired joint function. Disease-modifying anti-rheumatic drugs are considered as the first-line treatment to inhibit the progression of RA, and the treatment depends on the disease status assessment. The disease activity score 28 as clinical gold standard is extensively used for RA assessment, but it has the limitations of delayed assessment and the need for specialized expertise. It is necessary to discover biomarkers that can precisely monitor disease activity, and provide optimized treatment for RA patients. A total of 1,244 participants from two independent centers were divided into five cohorts. Cohorts 1-4 constituted sera samples of moderate to high active RA, low active RA, RA in remission and healthy subjects. Cohort 5 consisted of sera of RA, osteoarthritis (OA), ankylosing spondylitis (AS), systemic lupus erythematosus (SLE), primary Sjogren's syndrome (pSS) and healthy subjects. Biomarkers were found from cohorts 1-2 (screening sets), cohort 3 (discovery and external validation sets), cohort 4 (drug intervention set) and cohort 5 (biomarker-specific evaluation set). We found 68 upregulated and 74 downregulated proteins by TMT-labeled proteomics in cohort 1, and fibrinogen-like protein 1 (FGL1) had the highest area under the receiver operating characteristic curve (AUC) values in cohort 2. In cohort 3, in cross-comparison among moderate/high active RA, low active RA, RA in remission and healthy subjects, FGL1 had AUC values of approximately 0.9000 and predictive values of 90%. Additionally, FGL1 had a predictive value of 91.46% for moderate/high active RA vs. remission/low active RA and 80.77% for RA in remission vs. low active RA in cohort 4. Importantly, FGL1 levels had no significant difference in OA and AS compared with healthy persons. The concentrations in SLE and pSS were improved, but approximately 3-fold lower than that in active RA in cohort 5. In summary, FGL1 is a novel and specific biomarker that could be clinically useful for predicting progression of RA.

Discovery of Potential Serum Protein Biomarkers in Ankylosing Spondylitis Using Tandem Mass Tag-Based Quantitative Proteomics.

Ankylosing spondylitis (AS) is a systemic, chronic, and inflammatory rheumatic disease that affects 0.2% of the population. Current diagnostic criteria for disease activity rely on subjective Bath Ankylosing Spondylitis Disease Activity Index scores. Here, we aimed to discover a panel of serum protein biomarkers. First, tandem mass tag (TMT)-based quantitative proteomics was applied to identify differential proteins between 15 pooled active AS and 60 pooled healthy subjects. Second, cohort 1 of 328 humans, including 138 active AS and 190 healthy subjects from two independent centers, was used for biomarker discovery and validation. Finally, biomarker panels were applied to differentiate among active AS, stable AS, and healthy subjects from cohort 2, which enrolled 28 patients with stable AS, 26 with active AS, and 28 healthy subjects. From the proteomics study, a total of 762 proteins were identified and 46 proteins were up-regulated and 59 proteins were down-regulated in active AS patients compared to those in healthy persons. Among them, C-reactive protein (CRP), complement factor H-related protein 3 (CFHR3), α-1-acid glycoprotein 2 (ORM2), serum amyloid A1 (SAA1), fibrinogen γ (FG-γ), and fibrinogen ß (FG-ß) were the most significantly up-regulated inflammation-related proteins and S100A8, fatty acid-binding protein 5 (FABP5), and thrombospondin 1 (THBS1) were the most significantly down-regulated inflammation-related proteins. From the cohort 1 study, the best panel for the diagnosis of active AS vs healthy subjects is the combination of CRP and SAA1. The area under the receiver operating characteristic (ROC) curve was nearly 0.900, the sensitivity was 0.970%, and the specificity was 0.805% at a 95% confidence interval from 0.811 to 0.977. Using 0.387 as the cutoff value, the predictive values reached 92.00% in the internal validation set (62 with active AS vs 114 healthy subjects) and 97.50% in the external validation phase (40 with active AS vs 40 healthy subjects). From the cohort 2 study, a panel of CRP and SAA1 can differentiate well among active AS, stable AS, and healthy subjects. For active AS vs stable AS, the area under the ROC curve was 0.951, the sensitivity was 96.43%, the specificity was 88.46% at a 95% confidence interval from 0.891 to 1, and the coincidence rate was 92.30%. For stable AS vs healthy humans, the area under the ROC curve was 0.908, the sensitivity was 89.29%, the specificity was 78.57% at a 95% confidence interval from 0.836 to 0.980, and the coincidence rate was 83.93%. For active AS vs healthy subjects, the predictive value was 94.44%. The results indicated that the CRP and SAA1 combination can potentially diagnose disease status, especially for active or stable AS, which will be conducive to treatment recommendation for patients with AS.

A 12-week Baduanjin Qigong exercise improves symptoms of ankylosing spondylitis: A randomized controlled trial.

BACKGROUND AND PURPOSE: Therapeutic exercises are considered effective treatments for ankylosing spondylitis(AS). Current study aimed to evaluate efficacy and safety of Baduanjin qigong, a traditional Chinese exercise, for treatment of AS in a pilot RCT setting. MATERIALS AND METHODS: A total of 60 patients were randomly assigned, at a 1:1 ratio, to receive a 12-week Baduanjin qigong training(exercise group) or maintain their current lifestyle(no-treatment group). As primary outcomes, Bath Ankylosing Spondylitis Disease Activity Index(BASDAI) and other AS symptoms were assessed at baseline and end of treatment period. RESULTS: A total of 46 patients completed the study. At the end of treatment period, although total BASDAI scores were not statistically different, reduced scores were observed in the exercise group, compared to no-treatment group, with respect to fatigue(P = 0.03), intensity(P = 0.04) and duration(P = 0.01) of morning stiffness; exercise group also exhibited higher patient global assessment scores(P = 0.04). CONCLUSION: Baduanjin qigong exercise appeared to improve AS symptoms.

Drug-containing serum of Xinfeng capsules protect against H9C2 from death by enhancing miRNA-21 and inhibiting toll-like receptor 4/phosphorylated p-38 (p-p38)/p-p65 signaling pathway and proinflammatory cytokines expression.

OBJECTIVE: To investigate effect of drug-containing serum of Xinfeng capsules on myocardial cell growth. METHODS: Drug-containing serum of Xinfeng capsules rat models were established by intragastricly administrated Xinfeng capsules. MTT assay was used to evaluated H9C2 cells viability. H9C2 cells were divided into normal control group, triptolide group, lipopolysaccharide (LPS) group, drug-containing serum group and miRNA-21 inhibitor group. microRNA-21 (miRNA-21) inhibitor was structured and transfected into H9C2 cells. Western blot and immunofluorescence assay were applied to examine toll-like receptor 4 (TLR4), phosphorylated p-38 (p-p38) and p-p65 expression. Quantitative real-time PCR (qRT-PCR) was used to evaluated mRNA levels of miRNA-21. Enzyme linked immunosorbent (ELISA) was used to measure tumor necrosis factorα (TNF-α), IL-6 and IL-17 levels. RESULTS: Drug-containing serum treatment significantly increased cell viability compared to LPS treated group. qRT-PCR results indicated that miRNA-21 levels were significantly decreased in drug- containing serum group compared to LPS group. Early and late apoptosis in drug-containing serum group were significantly decreased compared to LPS group. Western blot and immunofluorescence assay results showed that TLR4, p-p38 and p-p65 levels in drug-containing serum group were significantly decreased compared to LPS group. ELISA findings indicated that drug-containing serum significantly decreased inflammatory cytokine levels of TNF-α, IL-6 and IL-17. CONCLUSION: Drug-containing serum of Xinfeng capsules protect against lipopolysaccharide instr- ucted H9C2 cells from death by enhancing miRNA- 21 and inhibiting TLR4/p-p38/p-p65 signaling pathway and proinflammatory cytokines expression.

Triptolide inhibits proliferation, differentiation and induces apoptosis of osteoblastic MC3T3­E1 cells.

Ankylosing spondylitis (AS) is characterized by the formation of bony spurs. Treatment of the resulting ankylosis, excessive bone formation and associated functional impairment, remain the primary therapeutic aims in research regarding this condition. Triptolide is the primary active component of the perennial vine Tripterygium wilfordii Hook. f., and has previously been demonstrated to exert anti­tumor activities including inhibition of cell growth and the induction of apoptosis, however, the effect of triptolide on osteoblasts remains to be elucidated. In the present study, the MC3T3­E1 mouse osteoblast cell line was treated with differing concentrations of triptolide for various intervals. Cell proliferation was detected using the bromodeoxyuridine assay, cell cycle and apoptosis were measured by flow cytometry, nuclear apoptosis was observed by Hoechst staining and associated proteins were determined via western blot analysis. The cells were then further incubated with osteogenic induction medium supplemented with triptolide for 7 or 12 days and the differentiation to osteoblasts was examined by picrosirius staining, observation of alkaline phosphatase activity and a calcium deposition assay. It was demonstrated that treatment with triptolide significantly inhibited osteoblast proliferation and induced cell cycle arrest and apoptosis of the osteoblasts. Furthermore, treatment with triptolide reduced collagen formation, alkaline phosphatase activity and calcium deposition. The present study demonstrated an inhibitory effect of triptolide on osteoblast proliferation and differentiation, and therefore suggests a potential therapeutic agent for the treatment of AS in the future.

Beneficial effects of tripterygium glycosides tablet on biomarkers in patients with ankylosing spondylitis.

The aim of the current study was to explore the effects and possible mechanisms of tripterygium glycosides tablet (TGT) in the treatment of active ankylosing spondylitis (AS). Thirty-six patients with active AS were given a 20 mg TGT treatment three times per day for 12 weeks, and 21 unrelated healthy controls were recruited as the control group. Efficacy measures included the Bath AS disease activity index (BASDAI), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) prior and subsequent to TGT treatment. Serum dickkopf homolog 1 (DKK1) and interleukin-17 (IL-17) levels before and after TGT treatment were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and ELISA assay. The levels of several serum biomarkers were determined by ELISA, including receptor activator of nuclear factor κ-B ligand (RANKL), osteoprotegerin (OPG), bone alkaline phosphatase (BAP), bone morphogenetic protein-2 (BMP-2), matrix metalloproteinase-3 (MMP-3), cross-linked telopeptide of type II collagen (CTX-II), vascular endothelial growth factor (VEGF), and prostaglandin E2 (PGE2). After 12 weeks of TGT treatment, the BASDAI score of the patients was significantly reduced (P<0.05), their levels of ESR and CRP were significantly reduced to a normal level (P<0.05, P<0.05), RT-PCR and ELISA showed a significant increase in the level of DKK1 expression (P<0.05) and a significant decreased IL-17 expression (P<0.05), there was a significant increase in the expression of OPG, BAP and BMP-2 (P<0.01, P<0.01, P<0.01) and a significant reduction in the expression levels of RANKL, CTX-II. MMP-3, PGE2, and VEGF (P<0.01, P<0.01, P<0.01, P<0.05, P<0.01) compared with those of the controls. TGT is effective at improving the signs and symptoms of patients with AS through the regulation of serum biomarkers, and the mechanisms may be associated with the anti-inflammatory effect, inhibition of new bone formation and potential bone-protective effects.

Hsp90 inhibitor PU-H71, a multimodal inhibitor of malignancy, induces complete responses in triple-negative breast cancer models.

Triple-negative breast cancers (TNBCs) are defined by a lack of expression of estrogen, progesterone, and HER2 receptors. Because of the absence of identified targets and targeted therapies, and due to a heterogeneous molecular presentation, treatment guidelines for patients with TNBC include only conventional chemotherapy. Such treatment, while effective for some, leaves others with high rates of early relapse and is not curative for any patient with metastatic disease. Here, we demonstrate that these tumors are sensitive to the heat shock protein 90 (Hsp90) inhibitor PU-H71. Potent and durable anti-tumor effects in TNBC xenografts, including complete response and tumor regression, without toxicity to the host are achieved with this agent. Notably, TNBC tumors respond to retreatment with PU-H71 for several cycles extending for over 5 months without evidence of resistance or toxicity. Through a proteomics approach, we show that multiple oncoproteins involved in tumor proliferation, survival, and invasive potential are in complex with PU-H71-bound Hsp90 in TNBC. PU-H71 induces efficient and sustained downregulation and inactivation, both in vitro and in vivo, of these proteins. Among them, we identify downregulation of components of the Ras/Raf/MAPK pathway and G(2)-M phase to contribute to its anti-proliferative effect, degradation of activated Akt and Bcl-xL to induce apoptosis, and inhibition of activated NF-kappaB, Akt, ERK2, Tyk2, and PKC to reduce TNBC invasive potential. The results identify Hsp90 as a critical and multimodal target in this most difficult to treat breast cancer subtype and support the use of the Hsp90 inhibitor PU-H71 for clinical trials involving patients with TNBC.