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1.  Relative impact of 3- and 5-hydroxyl groups of cytosporone B on cancer cell viability† 
MedChemComm  2012;4(2):332-339.
A novel and the shortest route, thus far, for preparing cytosporone B (Csn-B) is reported. Csn-B and two analogs were used to probe the importance of hydroxyl groups at the 3- and 5-positions of the Csn-B benzene ring in inhibiting the viability of human H460 lung cancer and LNCaP prostate cancer cells, inducing H460 cell apoptosis, and interacting with the NR4A1 (TR3) ligand-binding domain (LBD). These studies indicate that Csn-B and 5-Me-Csn-B, having a phenolic hydroxyl at the 3-position of their aromatic rings, had similar activities in inhibiting cancer cell viability and in inducing apoptosis, whereas 3,5-(Me)2-Csn-B was unable to do so. These results are in agreement with ligand-binding experiments showing that the interaction with the NR4A1 LBD required the presence of the 3-hydroxyl group.
doi:10.1039/C2MD20243C
PMCID: PMC4005383  PMID: 24795803
2.  Small Molecule-Induced Mitochondrial Disruption Directs Prostate Cancer Inhibition via Unfolded Protein Response Signaling 
Oncotarget  2013;4(8):1212-1229.
We previously identified SMIP004 (N-(4-butyl-2-methyl-phenyl) acetamide) as a novel inducer of cancer-cell selective apoptosis of human prostate cancer cells. SMIP004 decreased the levels of positive cell cycle regulators, upregulated cyclin-dependent kinase inhibitors, and resulted in G1 arrest, inhibition of colony formation in soft agar, and cell death. However, the mechanism of SMIP004-induced cancer cell selective apoptosis remained unknown. Here, we used chemical genomic and proteomic profiling to unravel a SMIP004-induced pro-apoptotic pathway, which initiates with disruption of mitochondrial respiration leading to oxidative stress. This, in turn, activates two pathways, one eliciting cell cycle arrest by rapidly targeting cyclin D1 for proteasomal degradation and driving the transcriptional downregulation of the androgen receptor, and a second pathway that activates pro-apoptotic signaling through MAPK activation downstream of the unfolded protein response (UPR). SMIP004 potently inhibits the growth of prostate and breast cancer xenografts in mice. Our data suggest that SMIP004, by inducing mitochondrial ROS formation, targets specific sensitivities of prostate cancer cells to redox and bioenergetic imbalances that can be exploited in cancer therapy.
PMCID: PMC3787152  PMID: 23902736
Prostate cancer; cell cycle arrest; apoptosis; oxidative stress; small molecule inhibitor; mitochondrial function
3.  Chemical genetics approach to restoring p27Kip1 reveals novel compounds with antiproliferative activity in prostate cancer cells 
BMC Biology  2010;8:153.
Background
The cyclin-dependent kinase (CDK) inhibitor p27Kip1 is downregulated in a majority of human cancers due to ectopic proteolysis by the ubiquitin-proteasome pathway. The expression of p27 is subject to multiple mechanisms of control involving several transcription factors, kinase pathways and at least three different ubiquitin ligases (SCFSKP2, KPC, Pirh2), which regulate p27 transcription, translation, protein stability and subcellular localization. Using a chemical genetics approach, we have asked whether this control network can be modulated by small molecules such that p27 protein expression is restored in cancer cells.
Results
We developed a cell-based assay for measuring the levels of endogenous nuclear p27 in a high throughput screening format employing LNCaP prostate cancer cells engineered to overexpress SKP2. The assay platform was optimized to Z' factors of 0.48 - 0.6 and piloted by screening a total of 7368 chemical compounds. During the course of this work, we discovered two small molecules of previously unknown biological activity, SMIP001 and SMIP004, which increase the nuclear level of p27 at low micromolar concentrations. SMIPs (small molecule inhibitors of p27 depletion) also upregulate p21Cip1, inhibit cellular CDK2 activity, induce G1 delay, inhibit colony formation in soft agar and exhibit preferential cytotoxicity in LNCaP cells relative to normal human fibroblasts. Unlike SMIP001, SMIP004 was found to downregulate SKP2 and to stabilize p27, although neither SMIP is a proteasome inhibitor. Whereas the screening endpoint - nuclear p27 - was robustly modulated by the compounds, SMIP-mediated cell cycle arrest and apoptosis were not strictly dependent on p27 and p21 - a finding that is explained by parallel inhibitory effects of SMIPs on positive cell cycle regulators, including cyclins E and A, and CDK4.
Conclusions
Our data provide proof-of-principle that the screening platform we developed, using endogenous nuclear p27 as an endpoint, presents an effective means of identifying bioactive molecules with cancer selective antiproliferative activity. This approach, when applied to larger and more diverse sets of compounds with refined drug-like properties, bears the potential of revealing both unknown cellular pathways globally impinging on p27 and novel leads for chemotherapeutics targeting a prominent molecular defect of human cancers.
doi:10.1186/1741-7007-8-153
PMCID: PMC3025922  PMID: 21182779
4.  SOCS2 negatively regulates growth hormone action in vitro and in vivo 
Journal of Clinical Investigation  2005;115(2):397-406.
Mice deficient in SOCS2 display an excessive growth phenotype characterized by a 30–50% increase in mature body size. Here we show that the SOCS2–/– phenotype is dependent upon the presence of endogenous growth hormone (GH) and that treatment with exogenous GH induced excessive growth in mice lacking both endogenous GH and SOCS2. This was reflected in terms of overall body weight, body and bone lengths, and the weight of internal organs and tissues. A heightened response to GH was also measured by examining GH-responsive genes expressed in the liver after exogenous GH administration. To further understand the link between SOCS2 and the GH-signaling cascade, we investigated the nature of these interactions using structure/function and biochemical interaction studies. Analysis of the 3 structural motifs of the SOCS2 molecule revealed that each plays a crucial role in SOCS2 function, with the conserved SOCS-box motif being essential for all inhibitory function. SOCS2 was found to bind 2 phosphorylated tyrosines on the GH receptor, and mutational analysis of these amino acids showed that both were essential for SOCS2 function. Together, the data provide clear evidence that SOCS2 is a negative regulator of GH signaling.
doi:10.1172/JCI200522710
PMCID: PMC546423  PMID: 15690087

Results 1-4 (4)