Shih-Hsien Chuang

Characterization of the biological activity of a potent small molecule Hec1 inhibitor TAI-1

BackgroundHec1 (NDC80) is an integral part of the kinetochore and is overexpressed in a variety of human cancers, making it an attractive molecular target for the design of novel anticancer therapeutics. A highly potent first-in-class compound targeting Hec1, TAI-1, was identified and is characterized in this study to determine its potential as an anticancer agent for clinical utility.MethodsThe in vitro potency, cancer cell specificity, synergy activity, and markers for response of TAI-1 were evaluated with cell lines. Mechanism of action was confirmed with western blotting and immunofluorescent staining. The in vivo potency of TAI-1 was evaluated in three xenograft models in mice. Preliminary toxicity was evaluated in mice. Specificity to the target was tested with a kinase panel. Cardiac safety was evaluated with hERG assay. Clinical correlation was performed with human gene database.ResultsTAI-1 showed strong potency across a broad spectrum of tumor cells. TAI-1 disrupted Hec1-Nek2 protein interaction, led to Nek2 degradation, induced significant chromosomal misalignment in metaphase, and induced apoptotic cell death. TAI-1 was effective orally in in vivo animal models of triple negative breast cancer, colon cancer and liver cancer. Preliminary toxicity shows no effect on the body weights, organ weights, and blood indices at efficacious doses. TAI-1 shows high specificity to cancer cells and to target and had no effect on the cardiac channel hERG. TAI-1 is synergistic with doxorubicin, topotecan and paclitaxel in leukemia, breast and liver cancer cells. Sensitivity to TAI-1 was associated with the status of RB and P53 gene. Knockdown of RB and P53 in cancer cells increased sensitivity to TAI-1. Hec1-overexpressing molecular subtypes of human lung cancer were identified.ConclusionsThe excellent potency, safety and synergistic profiles of this potent first-in-class Hec1-targeted small molecule TAI-1 show its potential for clinically utility in anti-cancer treatment regimens.

Synthesis and structure–activity relationship of 3-O-acylated (–)-epigallocatechins as 5α-reductase inhibitors

A series of 3-O-acylated (-)-epigallocatechins were synthesized and their inhibition of steroid 5α-reductase was studied. They were prepared from the reaction of EGCG with tert-butyldimethylsilyl chloride followed by reductive cleavage of the ester bond. The resultant (-)-epigallocatechins penta-O-tert-butyldimethylsilyl ether was esterified with different fatty acids then desilylated to provide the corresponding products. The activity of 3-O-acylated (-)-epigallocatechins increased with the increasing carbon numbers of the fatty acid moiety, reaching maximum for 16 carbon atoms (compound 4h) with an IC50 of 0.53 μM, which was ∼12-fold more potent than EGCG (IC50=6.29 μM). Introduction of monounsaturated fatty acid provided the most potent compound 6 (IC50=0.48 μM), which showed moderate anti-tumor activity in vivo.

Activity of a Novel Hec1-Targeted Anticancer Compound against Breast Cancer Cell Lines In Vitro and In Vivo

Current cytotoxic chemotherapy produces clinical benefit in patients with breast cancer but the survival impact is modest. To explore novel cytotoxic agents for the treatment of advanced disease, we have characterized a new and pharmacokinetically improved Hec1-targeted compound, TAI-95. Nine of 11 breast cancer cell lines tested were sensitive to nanomolar levels of TAI-95 (GI50 = 14.29–73.65 nmol/L), and more importantly, TAI-95 was active on a number of cell lines that were resistant (GI50 > 10 μmol/L) to other established cytotoxic agents. TAI-95 demonstrates strong inhibition of in vivo tumor growth of breast cancer model when administered orally, without inducing weight loss or other obvious toxicity. Mechanistically, TAI-95 acts by disrupting the interaction between Hec1 and Nek2, leading to apoptotic cell death in breast cancer cells. Furthermore, TAI-95 is active on multidrug-resistant (MDR) cell lines and led to downregulation of the expression of P-glycoprotein (Pgp), an MDR gene. In addition, TAI-95 increased the potency of cytotoxic Pgp substrates, including doxorubicin and topotecan. Certain clinical subtypes of breast cancer more likely to respond to Hec1-targeted therapy were identified and these subtypes are the ones associated with poor prognosis. This study highlights the potential of the novel anticancer compound TAI-95 in difficult-to-treat breast cancers. Mol Cancer Ther; 13(6); 1419–30. ©2014 AACR.

Design and synthesis of pyrrole–5-(2,6-dichlorobenzyl)sulfonylindolin-2-ones with C-3′ side chains as potent Met kinase inhibitors

Pyrrole–5-(2,6-dichlorobenzyl)sulfonylindolin-2-ones of scaffold 4 with various C-3′ side chains were designed as potent Met kinase inhibitors. Structural optimization led to compounds 10, 20, and 22–24 which demonstrated subnanomolar IC50 values in the biochemical assay. The potent compound 20 inhibited Met with IC50 value of 0.37 nM and the proliferation of MKN45 cells with IC50 of 0.22 μM. It suppressed Met autophosphorylation with the downstream signaling through Gab-1, PLC-γ, FAK, Akt, STAT3, and ERK in cell. Complete inhibition of STAT3 and ERK phosphorylation was observed in MKN45 cells treated with 20 at the concentration of 100 nM. A computation simulation study was performed to reveal the interaction of 20 with Met.