Transcription factor inhibitor(Jnana)

The 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]

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.