A novel histone deacetylase inhibitor, CKD5, has potent anti-cancer effects in glioblastoma.

There have been extensive efforts to improve the outcome of glioblastoma, but the prognosis of this disease has not been significantly altered to date. Histone deacetylase inhibitors (HDACIs) have been evaluated as promising anti-cancer drugs and regulate cell growth, cell cycle arrest and apoptosis in glioblastoma. Here, we demonstrated the therapeutic efficacy of a novel pan-HDACI, 7-ureido-N-hydroxyheptanamide derivative (CKD5), compared with traditional pan-HDACIs, such as suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA), in vitro and in vivo. Compared with SAHA and TSA, CKD5 had improved cytotoxic effects and induced apoptosis, anti-proliferative activity and cell cycle arrest at G2/M phase. Furthermore, CKD5 significantly reduced tumor volume and prolonged the survival in vivo compared with TSA, suggesting improved anti-cancer efficacy among HDACIs. Our results demonstrate that the novel HDACI CKD5 is a promising therapeutic candidate for glioblastoma.

Tubulin inhibitor identification by bioactive conformation alignment pharmacophore-guided virtual screening.

Microtubules are important cellular component that are critical for proper cellular function. Microtubules are synthesized by polymerization of αß tubulin heterodimers called protofilaments. Microtubule dynamics facilitate proper cell division during mitosis. Disruption of microtubule dynamics by small-molecule agents inhibits mitosis, resulting in apoptotic cell death and preventing cell cycle progression. To identify a novel small molecule that binds the αß tubulin interface to affect microtubule dynamics, we developed a bioactive conformation alignment pharmacophore (BCAP) model to screen tubulin inhibitors from a huge database. The application of BCAP model generated based on the known αß-tubulin interface binders enabled us to identify several small-molecules that cause apoptosis in human promyelocytic leukemia (HL-60) cells. Virtual screening combined with an in vitro assay yielded 15 cytotoxic molecules. In particular, ethyl 2-(4-(5-methyl-3-nitro-1H-pyrazol-1-yl)butanamido)-4-phenylthiophene-3-carboxylate (H05) inhibited tubulin polymerization with an IC50 of 17.6 µm concentration. The virtual screening results suggest that the application of an unbiased BCAP pharmacophore greatly eliminates unlikely compounds from a huge database and maximizes screening success. From the limited compounds tested in the tubulin polymerization inhibitor (TPI) assay, compound H05 was discovered as a tubulin inhibitor. This compound requires further structure activity optimization to identify additional potent inhibitors from the same class of molecules.

Synthesis and biological evaluation of aryloxazole derivatives as antimitotic and vascular-disrupting agents for cancer therapy.

A series of aryloxazole, thiazole, and isoxazole derivatives was synthesized as vascular-targeting anticancer agents. Antiproliferative activity and tumor vascular-disrupting activity of all of the synthesized compounds were tested in vitro using various human cancer cell lines and HUVECs (human umbilical vein endothelial cells). Several compounds with an arylpiperazinyl oxazole core showed excellent cytotoxicity and metabolic stability in vitro. Among this series, two representative compounds (6-48 and 6-51) were selected and tested for the evaluation of anticancer effects in vivo using tumor-bearing mice. Compound 6-48 effectively reduced tumor growth (42.3% reduction in size) at the dose of 100 mg/kg. We believe that compound 6-48 will serve as a good lead compound for antimitotic and vascular-disrupting agents; further investigation to improve the in vivo efficacy of this series is underway.

Identification of CKD-516: a potent tubulin polymerization inhibitor with marked antitumor activity against murine and human solid tumors.

Tubulin polymerization inhibitors had emerged as one of promising anticancer therapeutics because of their dual mechanism of action, i.e. apoptosis by cell-cycle arrest and VDA, vascular disrupting agent. VDAs are believed to be more efficient, less toxic, and several of them are currently undergoing clinical trials. To identify novel tubulin inhibitors that possess potent cytotoxicity and strong inhibition of tubulin polymerization as well as potent in vivo antitumor efficacy, we have utilized benzophenone scaffold. Complete SAR analysis of newly synthesized analogues that were prepared by incorporation of small heterocycles (C2, C4, and C5 position) into B-ring along with the evaluation of their in vitro cytotoxicity, tubulin polymerization inhibition, and in vivo antitumor activity allowed us to identify 22 (S516). Compound 22 was found to have potent cytotoxicity against several cancer cells including P-gp overexpressing MDR positive cell line (HCT15). It also induced cell cycle arrest at G(2)/M phase, which is associated with strong inhibition of tubulin polymerization. Its in vivo efficacy was improved by preparing its (l)-valine prodrug, 65 (CKD-516), which together with greatly improved aqueous solubility has shown marked antitumor efficacy against both murine tumors (CT26 and 3LL) and human xenogratfs (HCT116 and HCT15) in mice.

Synthesis and antibacterial activity of 1 beta-methyl-2-(5-substituted imidazolino pyrrolidin-3-ylthio)carbapenem derivatives.

The synthesis of a new series of 1 beta-methylcarbapenems containing a substituted imidazolino pyrrolidine moiety is described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria were tested and the effect of the substituent on the imidazoline ring was investigated. Compound 13 g which has a N-sulfonylmethyl substituted imidazoline moiety showed the most potent antibacterial activity.