OBJECTIVETo investigate the mechanism by which heat shock protein 90 (HSP90) regulates 26S proteasome in hyperthermia.

METHODSHyperthermic HepG2 cell models established by exposure of the cells to 42 degrees celsius; for 3, 6, 12, and 24 h were examined for production of reactive oxygen species (ROS) and cell proliferation, and the changes in Hsp90α and 26S proteasome were analyzed.

RESULTSROS production in the cells increased significantly after hyperthermia (F=28.958, P<0.001), and the cell proliferation was suppressed progressively as the heat exposure time extended (F=621.704, P<0.001). Hyperthermia up-regulated Hsp90α but decreased the expression level (F=164.174, P<0.001) and activity (F=133.043, P<0.001) of 26S proteasome. The cells transfected with a small interfering RNA targeting Hsp90α also showed significantly decreased expression of 26S proteasome (F=180.231, P<0.001).

CONCLUSIONThe intracellular ROS production increases as the hyperthermia time extends. Heat stress and ROS together cause protein denature, leading to increased HSP90 consumption and further to HSP90 deficiency for maintaining 26S proteasome assembly and stability. The accumulation of denatured protein causes unfolded protein reaction in the cells to eventually result in cell death.

HSP90 Heat-Shock Proteins ; metabolism ; Hep G2 Cells ; Hot Temperature ; Humans ; Proteasome Endopeptidase Complex ; metabolism ; RNA, Small Interfering ; genetics ; Reactive Oxygen Species ; metabolism ; Up-Regulation

Animals ; Cadherins ; metabolism ; Cell Cycle Proteins ; genetics ; metabolism ; Cell Differentiation ; Cell Line, Tumor ; Early Growth Response Protein 1 ; genetics ; metabolism ; Estradiol ; physiology ; Eukaryotic Initiation Factor-3 ; metabolism ; Genes, Tumor Suppressor ; physiology ; HSP90 Heat-Shock Proteins ; metabolism ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Iron ; metabolism ; Neoplasms ; metabolism ; pathology

Our previous studies indicate that phosphatidylinositol 4-kinase IIα can promote the growth of multi-malignant tumors via HER-2/PI3K and MAPK pathways. However, the molecular mechanisms of this pathway and its potential for clinical application remain unknown. In this study, we found that PI4KIIα could be an ideal combinatorial target for EGFR treatment via regulating EGFR degradation. Results showed that PI4KIIα knockdown reduced EGFR protein level, and the expression of PI4KIIα shows a strong correlation with EGFR in human breast cancer tissues (r = 0.77, P < 0.01). PI4KIIα knockdown greatly prolonged the effects and decreased the effective dosage of AG-1478, a specific inhibitor of EGFR. In addition, it significantly enhanced AG1478-induced inhibition of tumor cell survival and strengthened the effect of the EGFR-targeting anti-cancer drug Iressa in xenograft tumor models. Mechanistically, we found that PI4KIIα suppression increased EGFR ligand-independent degradation. Quantitative proteomic analysis by stable isotope labeling with amino acids in cell culture (SILAC) and LC-MS/MS suggested that HSP90 mediated the effect of PI4KIIα on EGFR. Furthermore, we found that combined inhibition of PI4KIIα and EGFR suppressed both PI3K/AKT and MAPK/ERK pathways, and resulted in downregulation of multiple oncogenes like PRDX2, FASN, MTA2, ultimately leading to suppression of tumor growth. Therefore, we conclude that combined inhibition of PI4KIIα and EGFR exerts a multiple anti-tumor effect. Dual inhibition of EGFR at protein and activity level via combinatorial blocking of PI4KIIα presents a novel strategy to combat EGFR-dependent tumors.
Animals ; Antineoplastic Agents ; pharmacology ; Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Cell Survival ; drug effects ; ErbB Receptors ; antagonists & inhibitors ; metabolism ; Female ; HSP90 Heat-Shock Proteins ; metabolism ; Humans ; MCF-7 Cells ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Minor Histocompatibility Antigens ; Mitogen-Activated Protein Kinases ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphotransferases (Alcohol Group Acceptor) ; antagonists & inhibitors ; genetics ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Quinazolines ; pharmacology ; Transplantation, Heterologous ; Tyrphostins ; pharmacology

Apoptosis ; drug effects ; Benzoquinones ; pharmacology ; Carcinoma, Non-Small-Cell Lung ; drug therapy ; metabolism ; pathology ; Drug Resistance, Neoplasm ; HSP90 Heat-Shock Proteins ; antagonists & inhibitors ; Humans ; Lactams, Macrocyclic ; pharmacology ; Lung Neoplasms ; drug therapy ; metabolism ; pathology ; Mutation ; Oncogene Proteins, Fusion ; antagonists & inhibitors ; genetics ; metabolism ; Protein Kinase Inhibitors ; therapeutic use ; Pyrazoles ; therapeutic use ; Pyridines ; therapeutic use ; Triazoles ; pharmacology

OBJECTIVETo investigate the expressions of GRα, GRβ, GRγ, GRp and heat shock protein 90 (HSP90) in primary immune thrombocytopenia (ITP) patients and their correlations with glucocorticoid resistance.

METHODSThe expressions of glucocorticoid receptors (GRα, GRβ, GRγ, GRp) mRNA and HSP90 in peripheral blood mononuclear cells of 40 newly diagnosed ITP patients and 29 healthy volunteers were examined by real time PCR. Of them, 28 patients received glucocorticoid (GC) therapy divided into GC sensitive group (GCS) and GC resistant group (GCR) according to GC response. GRα, GRβ, GRγ, GRp, HSP90 mRNA and HSP90/GRα were analyzed in paired groups.

RESULTSThe expression of HSP90 mRNA was significantly decreased in ITP patients \[0.91(0.48 - 2.21)\] than in normal subjects \[1.41(0.83 - 2.61)\] (P < 0.05). There were no significant differences in mRNA expressions of GRα, GRβ, GRγ, GRp and HSP90/GRα between ITP patients and normal controls. The expression of GRα mRNA in GCS patients was significant higher than in GCR patients (P < 0.05). Moreover, no significant differences in mRNA expressions of GRβ, GRγ, GRp and HSP90 and the ratio of HSP90 to GRα were observed between GCS and GCR patients.

CONCLUSIONThe expression of HSP90 mRNA decreased in adult ITP patients. GC resistance in adult ITP patients was associated with reduced expression of GRα. The very low expression of GRβ mRNA may be not involved in GC resistance in adult ITP.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Case-Control Studies ; Female ; Glucocorticoids ; metabolism ; HSP90 Heat-Shock Proteins ; genetics ; metabolism ; Humans ; Male ; Middle Aged ; RNA, Messenger ; genetics ; Receptors, Glucocorticoid ; metabolism ; Thrombocytopenia ; metabolism ; Young Adult

OBJECTIVETo evaluate the effect of heat shock protein 90 (HSP90) on hepatitis B virus (HBV) replication in hepatocytes and to investigate the related molecular mechanism.

METHODSA eukaryotic plasmid expressing human HSP90 was constructed (designated as HA-HSP90). HepG2 cells were co-transfected with HA-HSP90 and the HBV replicative plasmid HBV1.3. Expression of the exogenous HSP90 was assessed by Western blotting. Expression of the HBV surface antigen (HBsAg) was determined by enzyme-linked immunosorbent assay, and HBV replicative intermediates were detected by Southern blotting. Small interfering (si)RNAs were designed against HSP90 and TBK1 and transfected into the HepG2 cells to further assess the effects of HSP90 and its underlying mechanism. HSP90-mediated effects on the expression of interleukins IL-1b and IL-6 and the interferon response gene IFIT1 were assessed by quantitating mRNA levels with real time RT-PCR.

RESULTSThe HA-HSP90 plasmid successfully expressed exogenous HSP90 protein in HepG2 cells. The exogenous HSP90 was able to inhibit HBV replication and HBsAg expression. IFIT1 expression was up-regulated after HA-HSP90 transfection, but neither IL-1b nor IL-6 were affected. The siRNA-mediated TBK1 down-regulation had no effect on the HSP90-inhibited HBV replication.

CONCLUSIONHSP90 can inhibit HBV replication and TBK1 is not involved in this process.

HSP90 Heat-Shock Proteins ; genetics ; Hep G2 Cells ; Hepatitis B e Antigens ; metabolism ; Hepatitis B virus ; physiology ; Humans ; Protein-Serine-Threonine Kinases ; genetics ; Transfection ; Virus Replication

OBJECTIVETo investigate the expression of heat shock protein 90 (HSP90) on the cell surface of highly invasive human prostate cancer cells PC3 and its possible molecular mechanisms of its effect on cell invasion through analyzing FAK/Src signaling pathway.

METHODSThe expression of cell surface HSP90 on PC3 cells was studied by immunofluorescence staining and surface biotinylation assay respectively. A specific HSP90 antibody was used to inhibit the cell surface HSP90. In vitro cell invasion was assessed by modified Boyden chambers. Phosphorylated FAK on tyr 397, 576, 577 and 925, and phosphorylated c-Src on tyr 416 were examined by Western blot assay. The association between FAK and c-Src was analyzed by immunoprecipitation. The effects of FAK knockdown by siRNA or Src kinases inhibitor PP2, with or without anti-HSP90 antibody, on PC3 cell invasion were also evaluated.

RESULTSA pool of HSP90 was detected on the cell surface of PC3 cells. A specific HSP90 antibody significantly retarded tumor cell invasion. Concomitant with this finding, targeting cell surface HSP90 significantly inhibited the phosphorylations of FAK and c-Src, and also the interactions between FAK and c-Src. FAK knockdown or PP2 dramatically suppressed cell invasion, however, anti-HSP90 antibody didn't further inhibit cell invasion.

CONCLUSIONSCell surface HSP90 promotes human prostate cancer cell invasion through a FAK/c-Src signaling, with may be a novel therapeutic target against metastatic tumors.

Antibodies ; pharmacology ; Cell Line, Tumor ; Cell Membrane ; metabolism ; Focal Adhesion Protein-Tyrosine Kinases ; genetics ; metabolism ; Gene Knockdown Techniques ; HSP90 Heat-Shock Proteins ; immunology ; metabolism ; Humans ; Male ; Neoplasm Invasiveness ; Phosphorylation ; Prostatic Neoplasms ; metabolism ; pathology ; Pyrimidines ; pharmacology ; RNA, Small Interfering ; genetics ; Signal Transduction ; Transfection ; src-Family Kinases ; antagonists & inhibitors ; metabolism

This study was purposed to investigate the mechanism of C-reactive protein (CRP) on proliferation of U266 cells. The human multiple myeloma cell line U266 was incubated with human CRP (0, 5, 10, 20 mg/L) for 24 hours, then the proliferation level of U266 cells was detected by using blood analyser. The mRNA expressions of survivin and HSP90alpha were examined by RT-PCR. The results showed that the proliferation ratio was increased, as compared with the control group (p<0.05); furthermore, the mRNA levels of survivin and HSP90alpha were up-regulated in proportion to the increased CRP concentrations. There was significant correlation between expression of survivin and HSP90alpha (r=0.737, p<0.0001) in incubated cells. It is concluded that CRP can stimulate the proliferation of MM cells directly by up-regulating the expression of survivin and HSP90alpha in MM cells. CRP can be regarded as a potential target for MM treatment.
Apoptosis ; C-Reactive Protein ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; HSP90 Heat-Shock Proteins ; metabolism ; Humans ; Inhibitor of Apoptosis Proteins ; metabolism ; Multiple Myeloma ; metabolism ; pathology ; RNA, Messenger ; genetics

OBJECTIVEMyasthenia gravis is an autoimmunity disease and its pathogenesis has not been fully identified. Heat shock protein 90 (HSP90) shows an abnormal expression in other autoimmunity diseases. This study examined the mRNA expression of two isoforms of HSP90 in peripheral blood mononuclear cells (PBMC) and serum cortisol content in children with myasthenia gravis.

METHODSThirty-six children with myasthenia gravis and 19 healthy children were enrolled. Serum cortisol content was measured by the chemiluminescence assay. The expression of HSP90alpha and HSP90beta mRNA in PBMC was detected by the RT-PCR technique.

RESULTSThe mRNA expression of HSP90alpha (0.7329+/- 0.2120) and HSP90beta (0.7193+/- 0.2869) in children with myasthenia gravis was significantly higher than that in healthy controls (0.5574+/- 0.2084 and 0.4892+/- 0.2104 respectively) (P<0.01). Serum cortisol content (285.04+/- 146.39 nmol/L) in children with myasthenia gravis was also higher than that in the healthy controls (196.25+/- 64.52 nmol/L) (P<0.01).

CONCLUSIONSThe high mRNA expression of HSP90alpha and HSP90beta in PBMC might be associated with the development of myasthenia gravis. The high serum cortisol level indicates a high stress state or might be correlated to the glucocorticoid receptor abnormality in children with myasthenia gravis.

Child ; Child, Preschool ; Female ; HSP90 Heat-Shock Proteins ; genetics ; Humans ; Hydrocortisone ; blood ; Leukocytes, Mononuclear ; metabolism ; Male ; Myasthenia Gravis ; etiology ; metabolism ; RNA, Messenger ; blood

During carcinogenesis, NF-kappaB mediates processes associated with deregulation of the normal control of proliferation, angiogenesis, and metastasis. Thus, suppression of NF-kappaB has been linked with chemoprevention of cancer. Accumulating findings reveal that heat shock protein 90 (HSP90) is a molecular chaperone and a component of the IkappaB kinase (IKK) complex that plays a central role in NF-kappaB activation. HSP90 also stabilizes key proteins involved in cell cycle control and apoptosis signaling. We have determined whether the exogenous administration of isoflavone-deprived soy peptide prevents 7,12-dimethylbenz[alpha]anthracene (DMBA)-induced rat mammary tumorigenesis and investigated the mechanism of action. Dietary administration of soy peptide (3.3 g/rat/day) significantly reduced the incidence of ductal carcinomas (50%), the number of tumors per multiple tumor-bearing rats (49%; P < 0.05), and extended the latency period of tumor development (8.07 +/- 0.92 weeks) compared to control diet animals (10.80 +/- 1.30; P < 0.05). Our results have further demonstrated that soy peptide (1) dramatically inhibits the expression of HSP90, thereby suppressing signaling pathway leading to NF-kappaB activation; (2) induces expression of p21, p53, and caspase-3 proteins; and (3) inhibits expression of VEGF. In agreement with our in vivo data, soy peptide treatment inhibited the growth of human breast MCF-7 tumor cells in a dose-dependent manner and induced apoptosis. Taken together, our in vivo and in vitro results suggest chemopreventive and tumor suppressive functions of isoflavone-deprived soy peptide by inducing growth arrest and apoptosis.
9,10-Dimethyl-1,2-benzanthracene ; Adenocarcinoma/*prevention & control ; Animals ; Apoptosis/*drug effects ; Breast Neoplasms/chemically induced/pathology/*prevention & control ; Cell Line, Tumor ; Chemoprevention ; Female ; Gene Expression Regulation, Neoplastic ; HSP90 Heat-Shock Proteins/genetics/metabolism ; Humans ; Isoflavones/chemistry ; NF-kappa B/genetics/metabolism ; Peptides/chemistry/isolation & purification/therapeutic use ; Rats ; Rats, Sprague-Dawley ; Soybean Proteins/chemistry/*isolation & purification/*therapeutic use ; Soybeans/chemistry