AbstractThe heat shock protein (HSP) 90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) is currently in clinical trials because of its unique mechanism of action and antitumor activity. However, 17-AAG triggers the transcription and elevation of antiapoptotic HSP90, HSP70, and HSP27, which lead to chemoresistance in tumor cells. We hypothesized that inhibiting HSP90, HSP70, and HSP27 transcription may enhance 17-AAG–induced cell death in multiple myeloma cell lines. Actinomycin D (Act D), a clinically used agent and transcription inhibitor, was combined with 17-AAG. The concentrations for 17-AAG and Act D were selected based on the target actions and plasma levels during therapy. Inducible and constitutive HSP27, HSP70, and HSP90 mRNA and protein levels were measured by real-time reverse transcription-PCR and immunoblot assays. Compared with no treatment, Act D alone decreased HSP mRNA levels in MM.1S and RPMI-8226 cell lines. Combining Act D with 17-AAG did not attenuate 17-AAG–mediated increases in transcript levels of inducible HSP70; however, constitutive HSP mRNA levels were decreased. In contrast to its effect on mRNA levels, Act D was able to abrogate 17-AAG–mediated increases in all HSP protein levels. The cytotoxicity of combined Act D and 17-AAG was assessed. Treatment with Act D alone caused <40% cell death, whereas the combination of 17-AAG and Act D resulted in an increase of cell death in both multiple myeloma cell lines. In conclusion, these results indicate that 17-AAG–mediated induction of HSP70 and HSP27 expression can be attenuated by Act D and therefore can potentially improve the clinical treatment of multiple myeloma. [Cancer Res 2009;69(9):3947–54]

2007-01-01·Molecular Cancer Therapeutics2区 · 医学

XR5944: A potent inhibitor of estrogen receptors

2区 · 医学

Article

作者: De Alba, Adrian ; Sidell, Neil ; Punchihewa, Chandanamali ; Yang, Danzhou

AbstractThe anticancer drug XR5944 was originally developed as a topoisomerase inhibitor and was subsequently shown to be a transcription inhibitor. It has shown exceptional anticancer activity both in vitro and in vivo and was significantly more potent than traditional topoisomerase inhibitors. The solution structure of the XR5944/DNA complex recently obtained in our laboratory indicates that XR5944 bis-intercalates at the 5′-(TpG):(CpA) site of duplex DNA, which is found in the consensus DNA-binding site of estrogen receptor (ER). Thus, we tested the ability of XR5944 to inhibit ER activity both in vitro and in cultured cells. In electrophoretic mobility shift assays, it is seen that the DNA binding of recombinant ERα protein, as well as ER from nuclear extracts, is inhibited by XR5944 in a dose-dependent manner. In luciferase reporter assays, XR5944 inhibited the reporter gene expression from an estrogen response element–containing promoter but not from a basal promoter sequence that lacks any cis-acting elements. In contrast, the RNA polymerase inhibitor actinomycin D inhibits the transcription from both the above-mentioned promoters. The specificity of XR5944 activity is displayed by a separate reporter assay in which the transactivation of reporter gene expression by Sp1 proteins was not inhibited by XR5944. Collectively, these data suggest that XR5944 is capable of specifically inhibiting the binding of ER to its consensus DNA sequence and its subsequent activity. This represents a novel mechanism of ER inhibition, which may allow the development of agents capable of overcoming resistance to current antiestrogens. [Mol Cancer Ther 2007;6(1):213–9]

2000-10-01·Clinical & Laboratory Haematology

Surreptitious bleeding in surgery

Article

作者: Rice, L

Apart from inadequate surgical haemostasis, postoperative bleeding can be related to acquired disorders of platelet number, platelet function or coagulation proteins (e.g. Vitamin K deficiency, DIC or liver injury). We highlight our experience with three patients who suffered life-threatening bleeding in the postoperative setting. The three patients - a 47-year-old man and 70- and 74-year-old women -- all had negative histories for excessive bleeding with prior surgeries, and all had normal preoperative PT and aPTT tests. Surgeries were resection of ischaemic bowel, cholecystectomy and coronary artery bypass grafting. All patients experienced unexpected bleeding within the first few postoperative days requiring multiple red cell transfusions and surgical re-explorations. Evaluations within the first 4--7 days after surgery revealed that these three patients had developed prolonged aPTT due to demonstrable factor VIII antibodies initially at low titre. One patient was treated with high doses human factor VIII, corticosteroids, intravenous gammaglobulin and plasma exchanges. The inhibitor was no longer demonstrable after 6 weeks of such therapy, and he has remained in remission without therapy. The second patient was initially treated with high-dose human factor VIII infusions. Five months later, prednisone and 6-mercaptopurine were begun for worsening inhibitor titre and diffuse purpura and subcutaneous haematomas. The factor inhibitor remitted, but the patient died from liver failure related to post-transfusion hepatitis. The third patient was initially managed with high-dose human factor VIII. Two months later, worsening inhibitor titre and tongue haematoma was treated with activated prothrombin complex, corticosteroids and cyclophosphamide. Eight years later, she is on no therapy, demonstrates a mild bleeding tendency and has a stable low-titre inhibitor. There have been a few case reports of inhibitors to coagulation factors including factor VIII becoming manifest in the postoperative setting but surgery has not been widely recognized as an underlying cause for acquired haemophilia. This paper speculates on pathogenesis and reviews treatment options. This syndrome is remarkable for its abrupt onset in the first few postoperative days and for its substantial morbidity. The problem is potentially reversible with immunosuppressive therapy. Clinicians should be aware of this syndrome, considering acquired haemophilia in patients with unexpected postoperative bleeding.

100 项与 Transcription factor inhibitor(Jnana) 相关的药物交易

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