Retarded cell division in the zinc finger domain lacking lysine–threonine–serine-transfected MCF-7 cells

<p><b>Copyright information:</b></p><p>Taken from "The zinc finger domain of Wilms' tumor 1 suppressor gene (WT1) behaves as a dominant negative, leading to abrogation of WT1 oncogenic potential in breast cancer cells"</p><p>http://breast-cancer-research.com/content/9/4/R43</p><p>Breast cancer research : BCR 2007;9(4):R43-R43.</p><p>Published online 16 Jul 2007</p><p>PMCID:PMC2206716.</p><p></p> A typical result of three individual assays for the carboxy-fluorescein diacetate succinimidyl ester (CFSE) labeling profiles of gated transfectants of MCF-7 cells. The transfectants (CON and zinc finger domain lacking the lysine–threonine–serine insert (ZF - KTS)) and the days post G418 selection (day 1, day 4, day 7 and day 10) are indicated

Accelerated apoptosis in the zinc finger domain lacking lysine–threonine–serine-transfected MCF-7 cells

<p><b>Copyright information:</b></p><p>Taken from "The zinc finger domain of Wilms' tumor 1 suppressor gene (WT1) behaves as a dominant negative, leading to abrogation of WT1 oncogenic potential in breast cancer cells"</p><p>http://breast-cancer-research.com/content/9/4/R43</p><p>Breast cancer research : BCR 2007;9(4):R43-R43.</p><p>Published online 16 Jul 2007</p><p>PMCID:PMC2206716.</p><p></p> Dot plots of a representative experiment of flow cytometric analysis for staining of Annexin V–PE (horizontal axis) and 7-amino-actinomycin D (7-AAD) (vertical axis) in nontransfected MCF-7 cells (CON) and transfected MCF-7 cells (Vec, zinc finger domain lacking the lysine–threonine–serine insert (ZF - KTS) or full-length Wilms' tumor 1 suppressor gene (WT1)). Percentages of cell populations in the different quadrants are indicated. Days after G418 selection are shown

Decrease of endogenous WT1 abundance by overexpression of zinc finger domain in breast cancer cells

<p><b>Copyright information:</b></p><p>Taken from "The zinc finger domain of Wilms' tumor 1 suppressor gene (WT1) behaves as a dominant negative, leading to abrogation of WT1 oncogenic potential in breast cancer cells"</p><p>http://breast-cancer-research.com/content/9/4/R43</p><p>Breast cancer research : BCR 2007;9(4):R43-R43.</p><p>Published online 16 Jul 2007</p><p>PMCID:PMC2206716.</p><p></p> Northern blot: total RNAs were isolated from the stable transfectants of MCF-7 cells with either pcDNA3 control (CON) or the zinc finger domain lacking the lysine–threonine–serine insert (ZF - KTS) of Wilms' tumor 1 suppressor gene (WT1) expression plasmids as indicated, and were analyzed with WT1 and β-actin probes. Overexpressed WT1–ZF, endogenous WT1 (FL WT1) or β-actin RNA is indicated. Western immunoblot: whole cell extracts were prepared from the stable transfectants of MCF-7 cells or MDA468 cells with either pcDNAcontrol or ZF - KTS expression plasmids, and were analyzed by western blot with either anti-WT1 and β-actin antibodies. Overexpressed WT1–ZF, endogenous WT1 (FL WT1) and β-actin proteins are indicated

Alteration of expression of WT1 target genes in zinc finger domain lacking KTS-transfected MCF-7 cells

<p><b>Copyright information:</b></p><p>Taken from "The zinc finger domain of Wilms' tumor 1 suppressor gene (WT1) behaves as a dominant negative, leading to abrogation of WT1 oncogenic potential in breast cancer cells"</p><p>http://breast-cancer-research.com/content/9/4/R43</p><p>Breast cancer research : BCR 2007;9(4):R43-R43.</p><p>Published online 16 Jul 2007</p><p>PMCID:PMC2206716.</p><p></p> Transient and stable transfectants of MCF-7 cells were analyzed for the expression of Wilms' tumor 1 suppressor gene (WT1) target genes or nontarget genes (horizontal axis) with quantitative real-time PCR assays. The relative expression (vertical axis) of these genes in the transfected MCF-7 cells was calculated as compared with the pcDNAcontrol. Results are the average of three experiments. AREG, amphregulin; BASP1, brain acid soluble protein 1; KTS, lysine–threonine–serine; WT1, Wilms' tumor 1 suppressor gene; ZF, zinc finger domain

Inhibition of transcriptional activity of the WT1 promoter by its zinc finger domain

<p><b>Copyright information:</b></p><p>Taken from "The zinc finger domain of Wilms' tumor 1 suppressor gene (WT1) behaves as a dominant negative, leading to abrogation of WT1 oncogenic potential in breast cancer cells"</p><p>http://breast-cancer-research.com/content/9/4/R43</p><p>Breast cancer research : BCR 2007;9(4):R43-R43.</p><p>Published online 16 Jul 2007</p><p>PMCID:PMC2206716.</p><p></p> Schematic drawing for luciferase reporter constructs. The predominant transcription start site (+1) is indicated by an arrow. Small solid triangles indicate Wilms' tumor 1 suppressor gene (WT1) binding sites. MCF-7 cells and MDA468 cells were co-transfected with plasmids expressing the WT1 proteins (either pcDNAcontrol (CON), aminoterminal-only construct N-WT1, zinc finger domain lacking or with lysine–threonine–serine (ZF - KTS or ZF + KTS) or full-length WT1 vectors A~D), and either the pGL2 vector control or the differential WT1 promoter-driven luciferase constructs (horizontal axis), respectively. Luciferase activity was normalized with β-galactosidase activity and is expressed in relative luciferase activity as compared with the luciferase vector control (vertical axis). Results are the average of three experiments

Abrogation of WT1-mediated c-transactivation by the zinc finger domain lacking KTS in MCF-7 cells

<p><b>Copyright information:</b></p><p>Taken from "The zinc finger domain of Wilms' tumor 1 suppressor gene (WT1) behaves as a dominant negative, leading to abrogation of WT1 oncogenic potential in breast cancer cells"</p><p>http://breast-cancer-research.com/content/9/4/R43</p><p>Breast cancer research : BCR 2007;9(4):R43-R43.</p><p>Published online 16 Jul 2007</p><p>PMCID:PMC2206716.</p><p></p> The MCF-7 cells were transiently co-transfected with the reporter constructs (either pGL2 vector, XNM/Luc or Xmut/Luc), with expression plasmids of Wilms' tumor 1 suppressor gene (WT1) isoforms (either pcDNAvector, A, B, C or D) and with WT1–zinc finger domain (ZF) (either pcDNAcontrol (CON) or ZF lacking the lysine–threonine–serine insert (ZF-KTS)) as well as β-galactosidase expression plasmid, respectively. Relative luciferase activity (vertical axis) is indicated. Histograms show average of three independent experiments

Small Molecule STAT5-SH2 Domain Inhibitors Exhibit Potent Antileukemia Activity

A growing body of evidence shows that Signal Transducer and Activator of Transcription 5 (STAT5) protein, a key member of the STAT family of signaling proteins, plays a pivotal role in the progression of many human cancers, including acute myeloid leukemia and prostate cancer. Unlike STAT3, where significant medicinal effort has been expended to identify potent direct inhibitors, Stat5 has been poorly investigated as a molecular therapeutic target. Thus, in an effort to identify direct inhibitors of STAT5 protein, we conducted an <i>in vitro</i> screen of a focused library of SH2 domain binding salicylic acid-containing inhibitors (∼150) against STAT5, as well as against STAT3 and STAT1 proteins for SH2 domain selectivity. We herein report the identification of several potent (<i>K</i>_i < 5 μM) and STAT5 selective (>3-fold specificity for STAT5 cf. STAT1 and STAT3) inhibitors, <b>BP-1-107</b>, <b>BP-1-108</b>, <b>SF-1-087</b>, and <b>SF-1-088</b>. Lead agents, evaluated in K562 and MV-4-11 human leukemia cells, showed potent induction of apoptosis (IC₅₀’s ∼ 20 μM) which correlated with potent and selective suppression of STAT5 phosphorylation, as well as inhibition of STAT5 target genes <i>cyclin D1</i>, <i>cyclin D2</i>, <i>C-MYC</i>, and <i>MCL-1</i>. Moreover, lead agent <b>BP-1-108</b> showed negligible cytotoxic effects in normal bone marrow cells not expressing activated STAT5 protein. Inhibitors identified in this study represent some of the most potent direct small molecule, nonphosphorylated inhibitors of STAT5 to date