B1, a novel HDAC inhibitor, induces apoptosis through the regulation of STAT3 and NF-κB.

We previously demonstrated that B1 induced significant cytotoxic effects, cell cycle G1 arrest and apoptosis in human lung cancer A549 cells through the inhibition of DNA topoisomerase II activity. In the present study, we focused on the histone deacetylase (HDAC) modulation of B1 in A549 cells. HDACs, important enzymes affecting epigenetic regulation, play a crucial role in human carcinogenesis. Our findings showed that B1 could suppress the growth of A549 cells in vitro through the inhibition of HDAC activity. Additionally, B1 caused disruption of the mitochondrial membrane potential and induced DNA double-strand breaks (DSBs) in a dose- and time-dependent manner, which consequently led to cell apoptosis. We also observed that B1 inhibited cancer cell migration and angiogenesis-related signal expression, including vascular endothelial growth factor (VEGF) and pro-matrix metalloproteinases-2 and -9 (pro-MMP-2/9). Gelatin zymography suggested that B1 decreased pro-MMP-2 and pro-MMP-9 activity. Transcription factors, signal transducer and activator of transcription 3 (STAT3) and nuclear factor-κB (NF-κB), are vital players in the many steps of carcinogenesis. B1 showed significant dose-response inhibitory effects on cytoplasmic expression and nuclear translocation of both phosphorylated STAT3 (pSTAT3) and NF-κB. It has been well documented that reactivated telomerase confers cancer cells the ability to repair DNA. Real-time PCR results indicated that B1 inhibited STAT3 and NF-κB mRNA expression and telomerase activity. Taken together, our results demonstrated that B1 exerted significant inhibitory effects on HDAC, telomerase activities, oncogenic STAT3 and NF-κB expression. The inhibition of the intricate crosstalk between STAT3 and NF-κB may be a major factor in the molecular action mechanism of B1. The multiple targeting effects of B1 render it a potential new drug for lung cancer therapy.

Inhibition of Molecular Signaling in Huh-7 Cells by AM3: A Novel Chemotherapeutic Agent for Hepatocellular Carcinoma.

BACKGROUND: According to a review of recent literature, no previous studies have reported the dose-dependent selective inhibition of the antiproliferative activity using colony and sphere formation assays and immunoblotting in human hepatoma cells in response to doxorubicin and mitoxantrone structural analogs such as AM3. OBJECTIVE: We evaluated the anticancer activity of mitoxantrone (MIT) structural analogs 1,5-bis({2- [(2-hydroxyethyl) amino]ethyl}-amino)-anthracene-9,10-dione (AM3) in human hepatoma cells (Huh-7). METHODS: In this paper, we synthesized AM3 through the nucleophilic amino substitution of 1,5- dichloroanthraquinone with the corresponding dichloride groups under microwave-accelerated heating. The structural characteristics of AM3 were analyzed through ultraviolet-visible spectroscopy and nuclear magnetic resonance. In vitro activity of AM3 was measured using the dose-dependent selective inhibition of the antiproliferative activity using colony and sphere formation assays and immunoblotting in Huh-7. RESULTS: The antiproliferative activity of AM3 was determined using IC50 values as 2.03 and 1.70 µM for hepatocellular carcinoma cell lines Huh-7 and SK-Hep-1 cells, respectively. In addition, colony formation assay of Huh-7 cells revealed that AM3 significantly suppressed the mean colony formation rate from 99.9 % to 2.5 %, and growth inhibition rate of sphere cells was significant, in which 5.0 µM of AM3 inhibited up to 28.5 % cell growth in the Huh-7 sphere cells. Immunoblotting confirmed the overexpression of CD44, COX-2, p-Akt, and Akt. CONCLUSION: Thus, AM3 is a novel therapeutic agent for suppressing cancer stemness and inflammation signaling in Huh-7 cells.

Synthesis and antitumor activity of 1,8-diaminoanthraquinone derivatives.

Continuing our ongoing studies on cytotoxic substances, a series of regioisomeric disubstituted aminoanthraquinone (DAAQ) derivatives have been synthesized as cytotoxic activity based on a proposed bioactive amino conformation. To assess the biological activity of amino-substitution in the side-chains of anthraquinone located at positions 1 and 8 of the anthraquinone ring system. The aim of the study was to determine if members of the anthraquinone family could be used as adjuncts to increase the growth inhibiting effect of anticancer agents in rat glioma C6 cells, human hepatoma G2 cells and 2.2.15 cells. In vitro cytotoxicity data is reported for the compounds and some indications of structure--activity relationships have been discerned. A number of compounds were found to have good cytotoxicity against proliferation in these three cell lines. This has led to the discovery some of the DAAQ as a conformationally constrained structure possessing anticancer properties that displays cytotoxicity for these above cell lines and is being investigated further.

Human telomerase inhibition and cytotoxicity of regioisomeric disubstituted amidoanthraquinones and aminoanthraquinones.

Telomerase is an attractive target for the rational design of new anticancer drugs due to its central role in the control of cellular proliferation. A number of 1,4-disubstituted amidoanthraquinones and 1,5-disubstituted aminoanthraquinones that are related to mitoxantrone and ametantrone have previously been prepared. The present study details the effects on human telomerase of these new classes of 1,4- and 1,5-difunctionalized tricyclic anthraquinone compounds. We have used cytotoxicity assay, reporter SEAP assay to monitor the hTERT expression, and TRAP-G4 assay to measure the relative activity of these compounds, and have examined how the attached substituents affect their ability to influence telomerase. Cytotoxicity levels in human tumor cell lines were at comparable levels for several compounds. Structural and activity relationships indicated that the position of disubstituent side chains is important for its inhibitory effect. Moreover, a primary amine or tertiary amine on the substitution group appears to be required for the telomerase inhibitory effect. There is no significant correlation between telomerase activity and cytotoxicity. These symmetrical disubstituted anthraquinones may represent useful leads for the development of human telomerase inhibitors as potential anticancer agents, and the exact mode of intercalative binding is dictated by the positional placement of substituent side chains for effective telomerase inhibition.

Synthesis and structure-activity correlations of the cytotoxic bifunctional 1,4-diamidoanthraquinone derivatives.

Anthraquinone-based compounds are attractive target for the design of new anticancer drugs. We have previously described a series of 1,5- and 1,4-difunctionalized anthraquinones, which exhibit different spectra of potency, together with human telomerase evaluation. The present study details the preparation of further, distinct series of regioisomeric difunctionalized amidoanthraquinone and examines their in vitro cytotoxicity in C6, Hepa G2, and 2.2.15 cell lines. Two structurally related compounds, mitoxantrone and adriamycin, were tested in parallel as positive controls. The structure-activity relationships indicated amido substitution may lead to a different mechanism of cytotoxicity. Compounds, which have -(CH2)n- side chains terminating in basic groups such as aminoalkyl-substituted, showed cytotoxic activity in several cell lines. The exact mode of intercalative binding may be dictated by the positional placement of substituent side chains. Implications for amidoanthraquinone cytotoxicity as potential anticancer agents are discussed. In addition, we further delineate the nature of the pharmacophore for this class of compounds, which provides a rational basis for the structure-activity relationships.