Chunhao Yang

S9, a Novel Anticancer Agent, Exerts Its Anti-Proliferative Activity by Interfering with Both PI3K-Akt-mTOR Signaling and Microtubule Cytoskeleton

Background Deregulation of the phosphatidylinositol 3-kinases (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway plays a central role in tumor formation and progression, providing validated targets for cancer therapy. S9, a hybrid of α-methylene-γ-lactone and 2-phenyl indole compound, possessed potent activity against this pathway. Methodology/Principal Findings Effects of S9 on PI3K-Akt-mTOR pathway were determined by Western blot, immunofluorescence staining and in vitro kinas assay. The interactions between tubulin and S9 were investigated by polymerization assay, CD, and SPR assay. The potential binding modes between S9 and PI3K, mTOR or tubulin were analyzed by molecular modeling. Anti-tumor activity of S9 was evaluated in tumor cells and in nude mice bearing human cancer xenografts. S9 abrogated EGF-activated PI3K-Akt-mTOR signaling cascade and Akt translocation to cellular membrane in human tumor cells. S9 possessed inhibitory activity against both PI3K and mTOR with little effect on other tested 30 kinases. S9 also completely impeded hyper-phosphorylation of Akt as a feedback of inhibition of mTOR by rapamycin. S9 unexpectedly arrested cells in M phase other than G1 phase, which was distinct from compounds targeting PI3K-Akt-mTOR pathway. Further study revealed that S9 inhibited tubulin polymerization via binding to colchicine-binding site of tubulin and resulted in microtubule disturbance. Molecular modeling indicated that S9 could potentially bind to the kinase domains of PI3K p110α subunit and mTOR, and shared similar hydrophobic interactions with colchicines in the complex with tubulin. Moreover, S9 induced rapid apoptosis in tumor cell, which might reflect a synergistic cooperation between blockade of both PI3-Akt-mTOR signaling and tubulin cytoskeleton. Finally, S9 displayed potent antiproliferative activity in a panel of tumor cells originated from different tissue types including drug-resistant cells and in nude mice bearing human tumor xenografts. Conclusions/Significance Taken together, S9 targets both PI3K-Akt-mTOR signaling and microtubule cytoskeleton, which combinatorially contributes its antitumor activity and provides new clues for anticancer drug design and development.

Direct Synthesis of Diverse 2-Aminobenzo[b]thiophenes via Palladium-Catalyzed Carbon–Sulfur Bond Formation Using Na2S2O3 as the Sulfur Source

A novel and direct synthesis of various 2-aminobenzo[b]thiophenes has been developed. The reactions were catalyzed by a combination of Pd(dppf)Cl2 and dppf using odorless and cheap Na2S2O3 as the sulfur source. This strategy allowed us to synthesize important 2-aminobenzo[b]thiophene scaffold more efficiently and conveniently.

Copper-mediated, palladium-catalyzed cross-coupling of 3-iodochromones, thiochromones, and quinolones with ethyl bromodifluoroacetate.

The palladium-catalyzed cross-coupling reaction of 3-iodochromones, thiochromones, and quinolones with ethyl bromodifluoroacetate in the presence of a copper mediator is reported. Under optimized conditions, all reactions worked well and provided difluoro-containing products in moderate to excellent yields.

WJD008, a dual phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin inhibitor, prevents PI3K signaling and inhibits the proliferation of transformed cells with oncogenic PI3K mutant.

The phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling pathway is often constitutively activated in various human cancers, providing validated targets for cancer therapy. Among a series of 5-cyano-6-morpholino-4-substituted-pyrimidine analogs designed and synthesized based on PI3K target, 4-(2-(dimethylamino)vinyl)-2-(3-hydroxyphenyl)-6-morpholinopyrimidine-5-carbonitrile (WJD008) was selected for further pharmacological characterization because of its potent activity against PI3K signaling. WJD008 inhibited kinase activity of PI3Kα and mTOR with less activity against PIKK family members. In cellular settings, WJD008 abrogated insulin-like growth factor-I-activated PI3K-Akt-mTOR signaling cascade and blocked the membrane translocation of a pleckstrin homology domain containing enhanced green fluorescent protein-general receptor for phosphoinositides, isoform 1-pleckstrin homology fusion protein, suggesting down-regulation of phosphatidylinositol (3,4,5)-trisphosphate output induced by WJD008 resulted in inactivation of PI3K pathway. Consequently, WJD008 arrested cells in G1 phase without induction of apoptosis. Furthermore, WJD008 reversed the hyperactivation of the PI3K pathway caused by the oncogenic mutation of p110α H1047R and suppressed the proliferation and clonogenesis of transformed RK3E cells harboring this mutant. WJD008 was superior to the pan-PI3K inhibitor wortmannin against proliferation of a panel of cancer cells independently of their status of PI3K pathway or tissue originations. In summary, WJD008 is a potent dual PI3K/mTOR modulator with antiproliferative and anticlonogenic activity in tumor cells and transformed cells with PIK3CA mutant, which provides new clues for the design and development of this chemical scaffold as an anticancer drug.

Poly(ADP-ribose) polymerase inhibitors as promising cancer therapeutics

The year of 2005 was a watershed in the history of poly(ADP-ribose) polymerase (PARP) inhibitors due to the important findings of selective killing in BRCA-deficient cancers by PARP inhibition. The findings made PARP inhibition one of the most promising new therapeutic approaches to cancers, especially to those with specific defects. With AZD2281 and BSI-201 entering phase III clinical trials, the final application of PARP inhibitors in clinic would come true soon. This current paper will review the major advances in targeting PARP for cancer therapy and discuss the existing questions, the answers to which may influence the future of PARP inhibitors as cancer therapeutics.

Design, synthesis and biological evaluation of substituted 11H-benzo[a]carbazole-5-carboxamides as novel antitumor agents.

A series of novel 11H-benzo[a]carbazole-5-carboxamide derivatives were designed, synthesized and evaluated for their antitumor activity against human cancer A549 and HCT-116 cell lines. Most of the compounds showed potent antitumor activities, and compound 8 displayed remarkable in vitro and in vivo anticancer activity comparable to that of amonafide.

Novel rhein analogues as potential anticancer agents.

Two series of rhein analogues were synthesized with modification at the 3‐position. Their cytotoxicities were evaluated using an MTT assay. Among all the compounds synthesized, one compound showed the best potency, with an IC50 value of 2.7 μM against the HeLa cell line and 0.6 μM against the MOLT4 cell line.

Synthesis of isoquinolinone-based tricycles as novel poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors.

The isoquinolinone-based tricyclic compounds were designed and synthesized. Preliminary biological study of these compounds provided potent compounds 17a, 33b, 33c, 33d, and 33g with low nanomolar IC50s against PARP-1 enzyme.

Synthesis of Functionalized Chromeno[2,3-b]pyrrol-4(1H)-ones by Silver-Catalyzed Cascade Reactions of Chromones/Thiochromones and Isocyanoacetates.

A novel and convenient approach to the synthesis of chromeno[2,3-b]pyrrol-4(1H)-ones has been developed. Furthermore, the method involves a facile silver-catalyzed cascade cyclization reaction including an intramolecular C-O bond formation. The silver salt acts as a key promoter.

Synthesis of Multisubstituted 2-Aminopyrroles/pyridines via Chemoselective Michael Addition/Intramolecular Cyclization Reaction

A facile and efficient synthetic strategy to construct polysubstituted 2-aminopyrroles/pyridines was developed via chemoselective Michael addition/intramolecular cyclization reaction under very mild conditions. It suggested that the chemoselectivity of the process could be controlled by the leaving ability of the halides.