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Cells have different sets of molecules for performing an array of physiological functions. Nucleic acids have stored and carried the information throughout evolution, whereas proteins have been attributed to performing most of the cellular functions. To perform these functions, proteins need to have a unique conformation and a definite lifespan. These attributes are achieved by a highly coordinated protein quality control (PQC) system comprising chaperones to fold the proteins in a proper three-dimensional structure, ubiquitin-proteasome system for selective degradation of proteins, and autophagy for bulk clearance of cell debris. Many kinds of stresses and perturbations may lead to the weakening of these protective cellular machinery, leading to the unfolding and aggregation of cellular proteins and the occurrence of numerous pathological conditions. However, modulating the expression and functional efficiency of molecular chaperones, E3 ubiquitin ligases, and autophagic proteins may diminish cellular proteotoxic load and mitigate various pathological effects. Natural medicine and small molecule-based therapies have been well-documented for their effectiveness in modulating these pathways and reestablishing the lost proteostasis inside the cells to combat disease conditions. The present article summarizes various similar reports and highlights the importance of the molecules obtained from natural sources in disease therapeutics.
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Geldanamycin (1) was isolated as a major compound from Streptomyces zerumbet W14. It was then used as a precursor tosynthesize two new geldanamycins: 17-(tryptamine)-17-demethoxygeldanamycin (2) and 17-(5′-methoxytryptamine)-17-demethoxygeldanamycin (3). The cytotoxicity activity of these two new compounds was evaluated and comparedwith the cytotoxicity of compound 1. Cytotoxicity activity was evaluated against a normal cell line, and three cancercell lines using an 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) colorimetric assay. Thesolubility of these compounds was also determined. The solubility of compounds 2 and 3 in water was 290.69and 348.18 µM, higher than that of compound 1 by about 1.91 and 2.29 times, respectively. Compounds 2 and 3showed moderate cytotoxic activity on Vero and human cervical carcinoma cells with IC50 values of >200.00 µg/ml. The strongest cytotoxicity of compound 3 was observed in human breast carcinoma cells (MCF-7) and humanhepatocellular carcinoma cell line (HepG2) cells with IC50 values of 82.50 and 114.35 µg/ml, respectively, while theIC50 values of compound 2 against MCF-7 and HepG2 cells were 105.62 and 124.57 µg/ml, respectively. The findingsshowed that these new geldanamycin derivatives exhibited selective cytotoxicity toward some cancer cells at a lowerconcentration. Therefore, future studies on these compounds could be useful for the management of some cancers
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Two new geldanamycin derivatives such as 17-(tryptamine)-17-demethoxygeldanamycin (2) andC17 methoxyl of geldanamycin (1). Their antiviral activity was evaluated based on influenza virus propagation inembryonated chicken eggs and viral absorption by hemagglutination (HA) inhibition test. The findings indicatedthat these compounds inhibited viral propagation at a concentration of 12.5 µg/ml. For the viral absorption, onlycompounds 2 and 3 inhibited HA at a concentration of 50 µg/ml. The solubility of compounds 2 and 3 in waterwas 290 and 306 µM, higher than that of compound 1 about 1.91 and 2.01 times, respectively. The compounds 2and 3 showed a moderate cytotoxic activity on LLC-MK2 and Vero cells with IC50 values of >200.00 µg/ml. Theseresults demonstrated the invention of tryptamine-geldanamycin hybrids to prevent influenza virus infection in viralabsorption and viral propagation steps.
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Objective: To investigate the cytotoxic effects of geldanamycin on human ovarian cancer SKOV3 cells, and to explore the possible mechanisms of apoptosis and cell proliferation inhibition of SKOV3 cells induced by geldanamycin. Methods: MTT method was performed to evaluate the inhibitory effects of geldanamycin alone or in combination with cisplatin on proliferation of SKOV3 cells. Cell cycle and apoptosis rate of SKOV3 cells treated with geldanamycin were detected by flow cytometry. The expressions of Akt and Raf-1 proteins were examined by immunocytochemistry and flow cytometry. Results: The proliferation of SKOV3 cells was inhibited by different concentrations of geldanamycin in a time- and dose-dependent manners (P<0.05). Different concentrations of geldanamycin strengthened the inhibitory effect of cisplatin on proliferation of SKOV3 cells, and this inhibitory effect was strengthened with the increased concentration of geldanamycin within a certain concentration range. The apoptosis rate of SKOV3 cells was raised up gradually after treatment with 0-2000 nmol/L geldanamycin for 48 h, and the number of cells in G2/M phase was increased significantly (P<0.05). The results of immunocytochemistry and flow cytometry showed that the expressions of Akt and Raf-1 proteins in SKOV3 cells induced by geldanamycin were significantly down-regulated in a dose-dependent manner (P<0.05). Conclusion: Geldanamycin can inhibit the cell proliferation and induce the apoptosis of human ovarian cancer SKOV3 cells in vitro , which may be associated with downregulation of the expressions of Akt and Raf-1 proteins. Copyright© 2011 by TUMOR.
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Heat shock protein 90 (HSP90), one of the most abundant proteins in the cardiac cells is essential for cell survival. Previous studies have shown that angiotensin II induces cardiac cell hypertrophy. However, the role of HSP90 in the angiotensin II-induced cardiac hypertrophy is unclear. In this study, we showed that HSP90 regulated angiotensin II-induced hypertrophy via maintenance of the IkappaB kinase (IKK) complex stability in cardiac cells. An HSP90 inhibitor, geldanamycin (GA), significantly suppressed angiotensin II-induced [3H]leucine incorporation and atrial natriuretic factor expression in cardiac cells. GA also inhibited the NF-kappaB activation induced by angiotensin II. Importantly, treatment with GA caused a degradation of IKKalpha/beta; on the other hand, a proteasome-specific inhibitor restored the level of IKKalpha/beta. We also found that GA prevented HSP90-IKKs complex induced by angiotensin II in cardiac cells. The small interfering RNA (siRNA)-mediated knockdown of HSP90 expression significantly inhibited angiotensin II-induced cell hypertrophy and NF-kappaB activation. These results suggest that angiotensin II-induced cardiac hypertrophy requires HSP90 that regulates the stability and complex of IKK.
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Objective: Benzoquinone ansamycin antibiotic, geldanamycin (GA), is a new anticancer agent that could inhibit Hsp90 by occupying its NH2-terminal ATP-binding site. This study was to investigate the antitumor efficacy of GA on Her2/neu tyrosine kinase overexpressing human breast cancer cell line SKBr3. Methods: The degradation of Her2/neu tyrosine kinase was analyzed by Western blotting, the proliferation index was determined by MTT assay, cell cycle distribution was detected by flow cytometry, Cyclin D1 mRNA transcription was measured by RT-PCR and real-time PCR, and cell motility was evaluated by the cell culture insert model. Results: GA induced a dose- and a time-dependent degradation of the Her2/ neu tyrosine kinase protein and concurrently, the inhibition of cancer cell proliferation. The antitumor effects mediated by GA included: GA treatment decreased the survival rates of cancer cells, and led to a dose-dependent G1 arrest. Furthermore, this antitumor effect was proved to be related to declined transcription of Cyclin D1. Concurrently, the motility of cancer cells was reduced by GA. Conclusion: GA treatment could induce the degradation of Her2/neu tyrosine kinase efficiently, inhibit cancer cell proliferation and reduce motility in Her2/neu tyrosine kinase overexpressed human breast cancer cell line SKBr3.
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Objective Benzoquinone ansamycin antibiotic, geldanamycin (GA), is a new anticancer agent that could inhibit Hsp90 by occupying its NH2-terminal ATP-binding site. This study was to investigate the antitumor efficacy of GA on Her2/neu tyrosine kinase overexpressing human breast cancer cell line SKBr3. Methods The degradation of Her2/neu tyrosine kinase was analyzed by Western blotting, the proliferation index was determined by MTT assay,cell cycle distribution was detected by flow cytometry, Cyclin D1 mRNA transcription was measured by RT-PCR and real-time PCR, and cell motility was evaluated by the cell culture insert model. Results GA induced a dose- and a time-dependent degradation of the Her2/neu tyrosine kinase protein and concurrently, the inhibition of cancer cell proliferation. The antitumor effects mediated by GA included: GA treatment decreased the survival rates of cancer cells,and led to a dase-dependent G1 arrest. Furthermore, this antitumor effect was proved to be related to declined transcription of Cyclin D1. Concurrently, the motility of cancer cells was reduced by GA. Conclusion GA treatment could induce the degradation of Her2/neu tyrnsine kinase efficiently, inhibit cancer cell proliferation and reduce motility in Her2/nen tyrosine kinase overexpressed human breast cancer cell line SKBr3.
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Objective: To study the interaction between heat shock protein 90 (HSP90) and the survivin in human breast cancer cells and its effect on proliferation and apoptosis of tumor cells. Methods: The human breast cancer MDA-MB-231 cells were treated with an HSP90 inhibitor, geldanamycin (GA). The expression of phosphorylated signal transducers and activators of transcription 3 (P-STAT3) and survivin protein were detected by Western blotting. The mRNA transcription of sruvivin was determined by RT-PCR. The cell proliferation was measured by MTT assay. Apoptosis was examined by flow cytometry. Results: HSP 90 inhibitor GA reduced the expression of P-STAT3 and survivin, inhibited the proliferation, and induced apoptosis of human breast cancer MDA-MB-231 cells. Conclusion: HSP90 affected the transcription of survivin mRNA through activation of the JAK-STAT3 signaling pathway. Surviving-HSP90 interaction contributed to the promotion of the high-proliferation and low-apoptosis malignant behaviors of human breast cancer MDA-MB-231 cells.
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PURPOSE: Heat shock proteins (hsps) are molecular chaperones that are synthesized by cells in response to various stress conditions. The expression of hsps have been shown to be associated with carcinogenesis and the expression of hsps have been implicated in the biological behavior of tumors. Recently, hsps have emerged as novel molecular targets in anticancer protocols. The objectives of this study were to investigate the significance of hsp 70/90 in breast carcinogenesis and effect of geldanamycin (a blocker of hsp 90) and quercetin (a blocker of hsp 70) on growth inhibition in different breast cancer cell lines. METHODS: Breast tissues from 82 patients were obtained between June 2003 and May 2005 at the Department of Surgery, Hallym University Hospital. Expression of hsp 70/90 was studied by immunohistochemistry (IHC) on tissue sections from 63 breast carcinomas and 19 benign breast tissues. Both cytoplasmic and nuclear expression was measured. Expression of hsp 70/90 was also analyzed by use of a Western blot with the breast cancer cell lines. We next investigated the effects of blockers of hsp 70/90 on cell growth of the human breast cancer cell lines. RESULTS: More prominent hsp 90 expression was observed in malignant tissue than in benign tissue by both cytoplasmic and nuclear IHC staining (p<0.001, p<0.001). Nuclear hsp 90 expression was associated with a positive lymph node status (p=0.003) and the presence of poorly differentiated tumors (p=0.028). Expression of hsp 70 was not different in malignant and benign tissues as determined by both cytoplasmic and nuclear IHC staining. The breast cancer cell lines all expressed hsp 70/90. Geldanamycin markedly inhibited the cell growth of these breast cancer cell lines in a dosedependent manner and induced apoptosis in the cell lines. Quercetin inhibited cell growth of the cell lines less efficiently. CONCLUSION: The expression of hsp 90 was associated with breast carcinogenesis and the presence of more aggressive tumors. Geldanamycin inhibited cell growth of hsp 90 expressing breast cancer cell lines. We suggest that Hsp 90 may be a possible molecular target against breast cancer.
Subject(s)
Humans , Apoptosis , Blotting, Western , Breast Neoplasms , Breast , Carcinogenesis , Cell Line , Cytoplasm , Heat-Shock Proteins , Hot Temperature , Immunohistochemistry , Lymph Nodes , Molecular Chaperones , QuercetinABSTRACT
Objective To investigate the effect of geldanamycin(GA) on the expression of HSP(HSP90,HSP70,HSP27) and oncoprotein(mutant p53,CDK4) in human breast cancer cell line MDA-MB-435s.Methods Proliferation of MDA-MB-435s cells was measured with MTT assay.The mRNA expression levels of HSP90,HSP70 and HSP27 were detected by RT-PCR.The protein expression levels of HSP90,HSP70,HSP27,mutant p53 and CDK4 were detected by Western blot.Results GA inhibited the proliferation of MDA-MB-435s cells in a time-dose dependent manner.The expression level of mRNA and protein of HSP90,HSP70 and HSP27 were increased,and the increasing of HSP70 was the most significant,while the protein expression level of mutant p53 and CDK4 in MDA-MB-435s cells were reduced obviously after 48-hour treatment with 400 nmol/L GA as compared with that of control cells.Conclusion GA inhibits the proliferation of MDA-MB-435s cells by down-regulating the level of mutant p53 and CDK4 protein,and GA involves in the protection of cell stress through increasing the expression of HSP90,HSP70 and HSP27.
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Objective:To investigate the effects of HSP90 inhibitors Geldanamycin(GA) on invasion and motility potential in human breast cancer cell.Methods: The effects of HSP90 inhibitor GA on the adhesion?invasion and metastasis of human breast cancer line MDA-MB-231 and MDA-MB-435s in vitro were explored by MTT colorimetric and transwell chamber.Results: Treatd with GA,the adhesion? invasion and motility abilities of the MDA-MB-231 and MDA-MB-435s cells were decreased significantly as compared with the control guoup,(P
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Objective:To investigate the expression and effect on invasion and metastasis of HSP90 in human breast cancer cell line ZR-75-30 in vitro and the mechanism of anti-invasion.Methods:The protein expression level of HSP90 in ZR-75-30 before and after treatment with HSP90 inhibitor Geldanamycin was detected by Western-blotting;The effects of GA on the proliferation,invasion and motility of human breast cancer cell line ZR-75-30 in vitro were explored respectively by MTT colorimetric assay and transwell chamber.Results:After treatment with GA the protein expression level of HSP90 in ZR-75-30 was decreased,and the proliferation of ZR-75-30 cells was obviously inhibited in a dose and time-dependent manner.Compared with the control guoup,the adhesion,invasion and motility abilities of the ZR-75-30 cells were decreased significantly(P