One-pot synthesis of 1,4-dihydroxy-2-((E)-1-hydroxy-4-phenylbut-3-enyl)anthracene-9,10-diones as novel shikonin analogs and evaluation of their antiproliferative activities.

A series of shikonin analogs have been synthesized in a one-pot reaction of quinizarin with ß,γ-unsaturated aldehydes in MeOH under mild conditions and investigated for their cytotoxicity against four cancer cell lines and one normal cell line. The synthesized compounds were found to be cytotoxic against HeLa cells with no apparent toxicity against normal cell line. Further modification led to the discovery of a novel tetracyclic anthraquinone (4b/4b') with potent cytotoxic activities against cervical, breast and pancreatic cancer cell lines with no significant effect on the growth of the control mammary epithelial cell line MCF-10. The good cytotoxicity and selectivity of compound 4b/4b' suggest that it could be a promising lead for further optimization.

Synergy between PPARgamma ligands and platinum-based drugs in cancer.

PPARgamma is a member of the nuclear receptor family for which agonist ligands have antigrowth effects. However, clinical studies using PPARgamma ligands as a monotherapy failed to show a beneficial effect. Here we have studied the effects of PPARgamma activation with chemotherapeutic agents in current use for specific cancers. We observed a striking synergy between rosiglitazone and platinum-based drugs in several different cancers both in vitro and using transplantable and chemically induced "spontaneous" tumor models. The effect appears to be due in part to PPARgamma-mediated downregulation of metallothioneins, proteins that have been shown to be involved in resistance to platinum-based therapy. These data strongly suggest combining PPARgamma agonists and platinum-based drugs for the treatment of certain human cancers.

A novel platform for accelerated pharmacodynamic profiling for lead optimization of anticancer drug candidates.

Oncology drug discovery is, by definition, a target-rich enterprise. High-throughput screening (HTS) laboratories have supported a wide array of molecularly targeted and chemical genomic approaches for anticancer lead generation, and the number of hits emerging from such campaigns has increased dramatically. Although automation of HTS processes has eliminated primary screening as a bottleneck, the demands on secondary screening in appropriate cell-based assays have increased concomitantly with the numbers of hits delivered to therapeutic area laboratories. The authors describe herein the implementation of a novel platform using off-the-shelf solutions that have allowed them to efficiently characterize hundreds of HTS hits using a palette of Western blot-based pharmacodynamic assays. The platform employs a combination of a flatbed bufferless SDS-PAGE system, a dry ultra-rapid electroblotting apparatus, and a highly sensitive and quantitative infrared imaging system. Cumulatively, this platform has significantly reduced the cycle time for HTS hit evaluation. In addition, the routine use of this platform has resulted in higher quality data that have allowed the development of structure-activity databases that have tangibly improved lead optimization. The authors describe in detail the application of this platform, designated the Accelerated Pharmaco-Dynamic Profiler (APDP), to the annotation of inhibitors of 2 attractive oncology targets, BRAF kinase and Hsp90.

Hic-5 regulates an epithelial program mediated by PPARgamma.

PPARgamma is a dominant regulator of fat cell differentiation. However, this nuclear receptor also plays an important role in the differentiation of intestinal and other epithelial cell types. The mechanism by which PPARgamma can influence the differentiation of such diverse cell lineages is unknown. We show here that PPARgamma interacts with Hic-5, a coactivator protein expressed in gut epithelial cells. Hic-5 and PPARgamma colocalize to the villus epithelium of the small intestine, and their expression during embryonic gut development correlates with the transition from endoderm to a specialized epithelium; expression of both these factors is reduced in tumors. Forced expression of Hic-5 in colon cancer cells enhances the PPARgamma-mediated induction of several gut epithelial differentiation/maturation markers such as L-FABP, kruppel-like factor 4 (KLF4), and keratin 20. siRNA directed against Hic-5 specifically reduces PPARgamma-mediated induction of gut epithelial genes in colon cells and in an ex vivo model of embryonic gut differentiation. Finally, forced expression of Hic-5 during 3T3-L1 preadipocyte differentiation inhibits adipogenesis while inducing inappropriate expression of several mRNAs characteristic of gut epithelium in these mesenchymal cells. These results indicate that Hic5 is an important component in determining an epithelial differentiation program induced by PPARgamma.