cyclin-d1 and tanespimycin

As a heat shock protein 90 inhibitor, 17-allylamino-17‑demethoxygeldanamycin (17-AAG) has been studied in numerous types of cancer, however the effects of 17-AAG on apoptosis and the cell cycle of H446 cells remain unclear. In the current study, the MTT method was used to evaluate the inhibitory effects of different durations and doses of 17‑AAG treatment on the proliferation of H446 cells. The cells were stained with Annexin-fluorescein isothiocyanate/propidium iodide and measured by flow cytometry, and the gene and protein expression levels of signal transducer and activator of transcription 3 (STAT3), survivin, cyclin D1, cyt‑C, caspase 9 and caspase 3 were determined by reverse transcription‑quantitative polymerase chain reaction and western blot analysis. The results indicated that with treatment with 1.25‑20 mg/l 17‑AAG for 24 and 48 h, significant inhibition of H446 cell proliferation was observed in a time‑ and dose‑dependent manner. With treatment of 3.125, 6.25 and 12.5 mg/l 17‑AAG for 48 h, significant apoptosis and cell cycle arrest was observed. The results indicated that the gene and protein expression levels of STAT3, survivin and cyclin D1 were downregulated, and cyt‑C, caspase 9 and caspase 3 were upregulated by 17‑AAG in a dose-dependent manner when the cells were treated with 3.125 and 6.25 mg/l 17-AAG for 48 h. The results indicated that 17‑AAG is able to inhibit the cell proliferation, induce apoptosis and G2/M arrest and downregulate the gene and protein expression levels of STAT3, survivin and cyclin D1, and upregulate gene and protein expression of cyt‑C, caspase 9, caspase 3.

Topics: Apoptosis; Benzoquinones; Caspase 3; Caspase 9; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclin D1; G2 Phase Cell Cycle Checkpoints; HSP90 Heat-Shock Proteins; Humans; Inhibitor of Apoptosis Proteins; Lactams, Macrocyclic; RNA, Messenger; STAT3 Transcription Factor; Survivin

We have demonstrated that aryl hydrocarbon receptor (AhR) is overexpressed in lung adenocarcinoma (AD). AhR is usually associated with heat shock protein 90 (Hsp90) in the cytoplasm. 17-Allylamino-17-demethoxygeldanamycin (17-AAG), an Hsp90 inhibitor, is currently under evaluation for its anticancer activity in clinical trials. Here we investigated whether AhR plays a role in 17-AAG-mediated anticancer activity by functioning as a downstream target or by modulating its anticancer efficacy. AhR expression in lung AD cells was modulated by siRNA interference or overexpression. Tumor growth was determined with colony formation in vitro or in vivo. Anticancer activity of 17-AAG was determined by measuring cell viability, cell cycle distribution, and expression of cell cycle regulators. Proteins and mRNA levels were examined by immunoblotting and the real-time reverse transcription-polymerase chain reaction, respectively. In this study, AhR overexpression positively modulated growth of lung AD cells, at least partially, via RelA-dependent mechanisms. Although treatment with 17-AAG reduced AhR levels and AhR-regulated gene expression in lung AD cells, AhR expression increased anticancer activity of 17-AAG. In addition, 17-AAG treatment reduced cell viability, CDK2, CDK4, cyclin E, cyclin D1, and phosphorylated Rb levels in AhR-expressing lung AD cells. NAD(P)H:quinone oxidoreductase (NQO1), which is regulated by AhR, was shown to increase anticancer activity of 17-AAG in cells. Knockdown of NQO1 expression attenuated the reduction of cell cycle regulators by 17-AAG treatment in AhR overexpressed cells. We demonstrated that AhR protein not only functions as a downstream target of 17-AAG, but also enhances anticancer activity of 17-AAG in lung AD cells.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Animals; Antineoplastic Agents; Benzoquinones; Cell Cycle; Cell Line, Tumor; Cell Survival; Cyclin D1; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 4; Humans; Lactams, Macrocyclic; Lung Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; NAD(P)H Dehydrogenase (Quinone); Receptors, Aryl Hydrocarbon; RNA, Messenger; Xenograft Model Antitumor Assays

Our previous study showed that the combination of a histone deacetylase (HDAC) inhibitor and an HIV protease inhibitor is effective against renal cancer cells. Because HDAC inhibition disrupts the chaperon function of heat shock protein (HSP) 90, we hypothesized that the combination of 17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of HSP90, and the HIV protease inhibitor ritonavir would also act against renal cancer. The combination of 17-AAG and ritonavir induced apoptosis and inhibited the proliferation of renal cancer cells effectively. It also suppressed the expression of cyclin-dependent kinase 4 and cyclin D1, leading to the accumulation of the cells in the sub-G1 fraction. The expression of HSPs 27, 70 and 90 was increased by 17-AAG alone but reduced by 17-AAG combined with ritonavir. The combination decreased the expression of heat shock factor-1 (HSF-1), an HSP transcription factor, and this might be one of the mechanisms of the effect of the combination. We have also found that silencing of HSF-1 by siRNA inhibited the proliferation of renal cancer cells and that in surgically resected specimens the levels of HSF-1 expression in renal cancer tissue are higher than those in normal parenchyma. This is the first study showing the beneficial effect of combining 17-AAG and ritonavir and our data suggest that HSF-1 may be a novel therapeutic target in the treatment of renal cancer.

Topics: Antineoplastic Agents; Apoptosis; Benzoquinones; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclin D1; Cyclin-Dependent Kinase 4; DNA-Binding Proteins; Drug Synergism; G1 Phase Cell Cycle Checkpoints; Gene Expression; Gene Expression Profiling; Gene Knockdown Techniques; Heat Shock Transcription Factors; HSP90 Heat-Shock Proteins; Humans; Kidney Neoplasms; Lactams, Macrocyclic; Ritonavir; RNA Interference; Transcription Factors

Peritoneal or retro-peritoneal sarcomatosis related malignant ascites formation is a rare but serious consequence of the locoregional metastatic event. The present work aimed to study the effect of the Hsp90 inhibitor (17-AAG), an ansamycin analog, on cell cycle and DNA replication specific chaperone-clients interaction in the event of peritoneal sarcoma related malignant ascites formation in mouse model at the late stage of malignant growth.. We administered 17-AAG, an Hsp90 inhibitor, divided doses (330 μg/kg b.w./day for first five days then next ten days with166 μg/kg b.w./day) through intra-peritoneal route of inbred Swiss albino mice bearing full grown peritoneal malignant ascites of sarcoma-180. Our study was evaluated by peripheral blood hemogram analysis, malignant ascitic cytology, cell viability test, survival time and mitotic indexing. Furthermore, flowcytometric HSP90, TERT, CyclinD1, PCNA and GM-CSF expression analysis has been considered for special objective of the study.. Our experimental efforts reduced the aggressive proliferation of malignant ascites by drastic downregulation of TERT and cyclin D1 on the verge of cell cycle entry along with DNA replication processivity factor PCNA by directly modulating their folding machinery - heat shock protein 90. Consequently, we observed that malignant ascitic cells became error prone during the event of karyokinesis and produced micronucleus containing malignant cells with low viability. Peripheral neutrophilia due to over-expression of GM-CSF by the peritoneal malignant ascites were also controlled by the treatment with 17-AAG and overall, the treatment modality improved the median survival time.. Finally we can conclude that 17AAG administration might serve as a prospective pharmacological agent for the management of peritoneal sarcoma related malignant ascites and throws light towards prolonged survival of the patients concerned.

Topics: Animals; Ascites; Ascitic Fluid; Benzoquinones; Blood Cell Count; Cell Cycle; Cell Proliferation; Cell Survival; Cyclin D1; Flow Cytometry; HSP90 Heat-Shock Proteins; Lactams, Macrocyclic; Mice; Mitotic Index; Peritoneal Neoplasms; Sarcoma 180; Survival Analysis; Telomerase

Increased Akt phosphorylation was reported in cancer cell lines and tumor tissues of patients exposed to rapamycin, a response likely contributing to the attenuated antitumor activity of rapamycin. It is, therefore, necessary to develop and validate combination strategies to reverse rapamycin-induced Akt signaling. We now report that Akt activation in response to rapamycin is abrogated by 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat shock protein 90 (HSP90) inhibitor. Rapamycin/17-AAG combination results in an enhanced antiproliferative activity in both MCF-7 and MDA-MB-231 breast cancer cells. In combination 17-AAG confers potent suppression of Raf-MEK-extracellular signal-regulated kinase signaling, a pathway that is otherwise not inhibited by rapamycin individually. Importantly, 17-AAG cooperates with rapamycin to block the phosphorylation of the mammalian target of rapamycin at Ser2448, as well as its downstream effectors ribosomal p70 S6 kinase and eukaryotic initiation factor 4E binding protein 1, which is accompanied by a substantial reduction in cyclins D1 and E. The potency of rapamycin/17-AAG combination is not affected by the activation of insulin-like growth factor 1 receptor signaling, which has been previously shown to diminish the antiproliferative activity of rapamycin. Rapamycin/17-AAG combination alleviates the induction of HSP90 protein, a heat shock response frequently associated with 17-AAG monotherapy. Our findings establish a mechanistic rationale for a combination approach using rapamycin and 17-AAG in the treatment of breast cancer.

Topics: Benzoquinones; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cyclin D1; Cyclin E; Extracellular Signal-Regulated MAP Kinases; Female; HSP90 Heat-Shock Proteins; Humans; Lactams, Macrocyclic; Protein Kinases; Proto-Oncogene Proteins c-akt; raf Kinases; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Mantle cell lymphoma (MCL), a distinct type of non-Hodgkin lymphoma, is characterised by the overexpression of cyclin D1. Heat shock protein 90 (HSP90) is a molecular chaperon to proteins that regulate cell cycle and survival. 17-allylamino-17-demethoxy-geldanamycin (17-AAG), a HSP90 small molecule inhibitor, induced G(0/1) cell cycle arrest and cell death in a dose- and time-dependent manner in MCL cell lines. This effect was associated with the downregulation of cyclin D1, cdk4 and Akt, depletion of Bid, and activation of the intrinsic/mitochondrial caspase pathway. These data suggest that 17-AAG may have a potential therapeutic value in patients with MCL.

Topics: Antineoplastic Agents; Apoptosis; Benzoquinones; BH3 Interacting Domain Death Agonist Protein; Caspase 9; Caspases; Cell Cycle; Cyclin D1; Down-Regulation; Drug Evaluation, Preclinical; Enzyme Activation; Gene Expression Regulation, Neoplastic; HSP90 Heat-Shock Proteins; Humans; Lactams, Macrocyclic; Lymphoma, Mantle-Cell; Neoplasm Proteins; Proto-Oncogene Proteins c-akt; Tumor Cells, Cultured

Ansamycin antibiotics, such as 17-allylaminogeldanamycin (17-AAG), bind to Hsp90 and regulate its function, resulting in the proteasomal degradation of a subset of signaling proteins that require Hsp90 for conformational maturation. HER2 is a very sensitive target of these drugs. Ansamycins cause RB-dependent G1 arrest that is associated with loss of D-cyclins via a PI3 kinase, Akt dependent pathway. Downregulation of D-cyclin was due, in part, to loss of Akt expression in response to drug. Moreover, in HER2 overexpressing breast cancer cells, 17-AAG caused rapid inhibition of Akt activity prior to any change in Akt protein. Ansamycins caused rapid degradation of HER2 and a concomitant loss in HER3 associated PI3 kinase activity. This led to a loss of Akt activity, dephosphorylation of Akt substrates, and loss of D-cyclin expression. Introduction into cells of a constitutively membrane bound form of PI3 kinase prevented the effects of the drug on Akt activity and D-cyclins. Thus, in breast cancer cells with high HER2, Akt activation by HER2/HER3 heterodimers is required for D-cyclin expression. In murine xenograft models, non-toxic doses of 17-AAG markedly reduced the expression of HER2 and phosphorylation of Akt and inhibited tumor growth. Thus, pharmacological inhibition of Akt activation is achievable with ansamycins and may be useful for the treatment of HER2 driven tumors.

Topics: Animals; Antibiotics, Antineoplastic; Benzoquinones; Blotting, Western; Breast Neoplasms; Cell Division; Cyclin D; Cyclin D1; Cyclin D3; Cyclins; Dimerization; Dose-Response Relationship, Drug; Enzyme Activation; Female; G1 Phase; Gene Expression Regulation, Neoplastic; Humans; Lactams, Macrocyclic; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Receptor, ErbB-2; Rifabutin; Transplantation, Heterologous; Tumor Cells, Cultured