Ji Wang Chern

Investigation of anticancer mechanism of thiadiazole-based compound in human non-small cell lung cancer A549 cells.

In this study, we have synthesized several compounds and examined their cytotoxic effects on human non-small cell lung cancer A549 cells. We found that GO-13 ((E,E)-2,5-bis[4-(3-dimethyl-aminopropoxy)styryl]-1,3,4-thiadiazole) is the most effective one by the MTT assay. Furthermore, the GO-13-induced apoptotic reaction was identified based on several criteria, such as negative release reaction of lactate dehydrogenase and positive labeling of annexin V and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) techniques. GO-13 induced the apoptosis in A549 cells in a concentration- and time-dependent manner. The data demonstrate that the regulations of p38 mitogen-activated protein kinase and protein kinase C was not involved in the GO-13-mediated mechanism. However, GO-13 significantly induced a down-regulation of Bcl-X(L) expression in a short-term treatment (less than 3hr), whereas stimulated up-regulation of Bax expression in a long-term treatment (24hr) indicating their involvement in GO-13 action. GO-13-mediated apoptosis is also positively correlated with the increase in caspase-3 activity. Worth noting is the fact that GO-13 did not modify the phosphorylation level of Akt/protein kinase B (PKB) until a 24-hr exposure was carried out indicating that the inhibition of Akt/PKB activation was involved in the late-phase apoptosis. Besides the anticancer activity, GO-13 also showed equivalent anti-angiogenic activity in the nude mice angiogenesis model. In summary, we conclude that GO-13 is the most effective anticancer compound in our screening tests. It induced the early-phase apoptosis in A549 cells via the Bcl-X(L) down-regulation, and that of the late-phase through up-regulation of Bax expression as well as inhibition of Akt/PKB activation.

Identification of Apoptotic and Antiangiogenic Activities of Terazosin in Human Prostate Cancer and Endothelial Cells

PURPOSEnIt has been suggested that terazosin has an inhibitory effect on prostate tumor growth. We determined if terazosin action contributes to direct suppression of the angiogenic effect.nnnMATERIALS AND METHODSnPC-3 cells and primary cultures of human benign prostatic cells were used in this study. The cytotoxic effect was examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and lactate dehydrogenase release reaction. The in vivo angiogenic effect was determined in nude mice models, followed by histological examination and quantification by the hemoglobin detection assay. In vitro determination of cell migration, proliferation and tube formation was performed in cultured human umbilical vein endothelial cells. RESULTS Terazosin induced cytotoxicity in PC-3 and human benign prostatic cells with an IC50 of more than 100 microM. The positive terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling and lactate dehydrogenase release reaction was associated with terazosin induced cytotoxicity, indicating apoptotic and necrotic cell death. Furthermore, cytotoxicity due to terazosin action was not a common characteristic of a quinazoline based structure. Terazosin significantly inhibited vascular endothelial growth factor induced angiogenesis in nude mice with an IC50 of 7.9 microM., showing that it had a more potent anti-angiogenic than cytotoxic effect. Terazosin also effectively inhibited vascular endothelial growth factor induced proliferation and tube formation in cultured human umbilical vein endothelial cells (IC50 9.9 and 6.8 microM., respectively).nnnCONCLUSIONSnTogether our data suggest that terazosin shows direct anti-angiogenic activity through the inhibition of proliferation and tube formation in endothelial cells. This action may partly explain the in vivo antitumor potential of terazosin.

Nucleosides. IX. Synthesis of Purine N 3,5′‐Cyclonucleosides and N 3,5′‐Cyclo‐2′,3′‐seconucleosides via Mitsunobu Reaction as TIBO‐like Derivatives

The Mitsunobu reaction was applied to prepare, in one step, purine N 3,5′‐cyclonucleosides 10a–d. A subsequent ring opening in the ribose moiety of the resultant N 3,5′‐nucleosides by sodium periodate led to the corresponding N 3,5′‐cyclo‐2′,3′‐seconucleosides. These products consist of 5‐, 6‐, and 7‐membered tricyclic system which is the basic skeleton of TIBO derivatives, known antiviral agents. #Previous paper in this series: Ref. 1. †In honor and celebration of the 70th birthday of Professor Leroy B. Townsend.

An improved screening model to identify inhibitors targeting zinc-enhanced amyloid aggregation

Zinc, which is abundant in senile plaques consisting mainly of fibrillar beta-amyloid (Abeta), plays a critical role in the pathogenesis of Alzheimers disease. Treatment with zinc chelators such as clioquinol has been used to prevent Abeta aggregation in Alzheimers patients; however, clioquinol produces severe side effects. A simple, easy, inexpensive, and versatile screen to identify zinc chelators for inhibition of Abeta aggregation is currently unavailable. We thus developed a high-throughput screen that identifies zinc chelators with anti-Abeta aggregation activity. The recombinant Abeta peptides, aggregated on solid-phase microplates, formed Abeta-immunopositive beta-sheet-containing structures in the presence of zinc. Formation of these Abeta fibrils was specifically blocked by metal ion chelators. This screening model improves identification of zinc-enhanced Abeta fibrils and anti-Abeta aggregation mediated by zinc chelating. The convenient system could qualitatively and quantitatively assay a large sample pool for Abeta aggregation inhibition and dissolution of Abeta aggregates. This screen is practical, reliable, and versatile for comprehensive detection of amyloid fibrillation and identification of inhibitors of Abeta aggregation.