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Aconitum carmichaeli Debx. is a traditional Chinese medicine commonly employed for curing a wide array of diseases in East Asia. From the ethyl acetate soluble fraction of the methanolic extracts of A carmichaeli, a new alkaloid, aconitamide (1), along with eighteen known compounds 2–19 were isolated by column chromatography and identified on the basis of spectroscopic analyses. The anti-telomerase activity of 1–19 was also assessed, but no activity was found, even at a concentration higher than 30 μM.

Two new lignans, (8 S,8′ S)-4,3′-dihydroxy-3,4′,5′-trimethoxylignan-9′,9-olide (1) and trans–4′,8,8′-trihydroxy-3′-methoxy-3,4-methylenedioxylignan-9′,9-olide (2), were isolated from the wood of Cunninghamia konishii. Their structures were determined by analysis of spectroscopic data.

A variety of functionalities were introduced at 2-aroylquinoline's C5 position, which is considered equivalent to C-3' of the B-ring of CA4, via Suzuki arylation, Sonogashira ethynylation, and Rosenmund-von Braun cyanation. These substitutions are rarely utilized in the modification of 3'-OH of CA4. The resulting products 6 and 7 having cyano and ethynyl groups exhibited comparable antiproliferative and tubulin inhibitory activities to colchicine.

The Nrf2/ARE pathway plays an important role in inducing phase II detoxifying enzymes and antioxidant proteins, and has been considered as a potential target for cancer chemoprevention by eliminating harmful reactive oxygen species (ROS) or reactive intermediates generated from carcinogens. The objectives of this study were to identify a novel Nrf2/ARE activator and to investigate the mechanistic signaling pathway involved in the activation of Nrf2-mediated cytoprotective effects against oxidative-induced cell injury. A stable ARE-driven luciferase reporter cell line was established to screen the potentially cytoprotective compound. 4-Ketopinoresinol (4-KPR), the (−) double cyclized type of lignan obtained from adlay (Coix lachrymal-jobi L. var. ma-yuen Stapf), more effectively activates ARE-driven luciferase activity than the classical ARE activator, tert-butylhydroquinone. 4-KPR treatment resulted in a transient increase in AKT phosphorylation and subsequent phosphorylation and nuclear translocation of Nrf2, along with increased expression of ARE-dependent cytoprotective genes, such as heme oxygenase-1 (HO-1), aldo-keto reductases, and glutathione synthetic enzyme, and their protein products. 4-KPR suppresses oxidative stress-induced DNA damage and cell death via up-regulation of HO-1. Inhibition of PI3K/AKT signal by chemical inhibitors or RNA interference suppressed Nrf2 activation and HO-1 up-regulation. These observations in an ARE-regulated gene system suggest that 4-KPR is a novel Nrf2/ARE-mediated transcription activator, activates the Nrf2/HO-1 axis, and protects against oxidative stress-induced cell injury via activation of PI3K/AKT signaling. These results may have relevance to the clinical application of 4-KPR and its significance in cancer chemoprevention. The study was supported by grants of DOH100-TD-C-111-004, NSC98-2320-B-400-003-MY3, and NSC99-2323-B-400-006. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A83.

Identification of a single agent that is able to target tumor cells, rapidly destroy tumor vasculature and inhibit angiogenesis could be an ideal approach for targeting solid tumors. We recently discover a novel sulfonamide compound, 7-aryl-indoline-1-benzene-sulfonamide (MPT0B098), as a potent microtubule inhibitor through binding to the colchicine binding site of tubulin. MPT0B098 is active against various human cancer cell growth with IC50 values ranged from 70-300 nM. Notably, HUVEC cells exhibit less susceptibility to the inhibitory effect of MPT0B098 with an IC50 of 510 nM. In addition, MPT0B098 exhibits no cross resistance with vincristine, paclitaxel, etoposide and camptothecin-resistant cell lines. Interestingly, MPT0B098 is still active toward cells (KB L30) with beta1-tubulin mutation. MPT0B098 arrests cells in G2/M phase and subsequently induces cell apoptosis through the caspase-dependent apoptotic pathway. In addition, using sub-lethal dose, MPT0B098 effectively suppressed to the tube formation and migration of HUVECs induced by VEGF. The expression levels of HIF-1alpha and VEGF were significantly inhibited in a concentration-dependent manner by MPT0B098 under hypoxic condition. Furthermore, HIF-1alpha-regulated genes, including cathepsin D, PDGF, VEGF, and VHL, were found to be down-regulated by MPT0B098 in A549 cells. Moreover, the decrease of the amount of HuR, a HIF-1alpha mRNA stability protein, translocated from nuclear to cytoplasm and suppression of AKT activity were coincided with decreased amount of HIF-1alpha mRNA by MPT0B098 treatment under hypoxia condition. MPT0B098 significantly suppressed tumor growth and microvessel density of tumor in H460 and KB-Vin10 xenografted mouse model. Taken together, our results indicate that MPT0B098 is a promising anticancer drug with potential for the treatment of human malignancies. (The study was supported by grants of DOH99-TD-C-111-004 from Department of Health and CA-099-PP-02 from National Health Research Institutes, Taiwan, R.O.C.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4461. doi:10.1158/1538-7445.AM2011-4461

Etoposide (VP-16), a DNA topoisomerase II poison, is an important clinical used chemotherapeutic agent for human oral malignancies. An etoposide-resistant cell line, KB-7D, has been generated from human oral epidermoid carcinoma KB cells to investigate the mechanism of action of drug resistance in oral malignancies. Previous studies revealed that KB-7D cells were approximately 50-fold more resistant to etoposide as compared to parental KB cells. It also exhibited cross-resistant to chemotherapeutic agents such as doxorubicin. This multi-drug resistance may be caused by the over-expression of ABCC1, leading to the decrease in drug accumulation in KB-7D cells. Our current work continues the effort to investigate the mechanism of regulation of ABCC1 expression in the etoposide-derived drug resistant cells and subsequently find the molecular target that can be used to restore therapeutic efficacy in chemo-refratory cancers. Down-regulation of ABCC1 by RNA interference and a selective inhibitor, MK-571, significantly enhanced the chemosensitivity to etoposide and doxorubicin in KB and KB-7D cells. To further determine the possible transcriptional factors that regulate the ABCC1 transactivation, the promoter region of ABCC1 was examined. A NRF2 binding sequence, antioxidant responsive element (ARE), has been found locate in the ABCC1 promoter at -470 to -458 upstream from the transcription start site. Real-time RT-PCR and Western blot analyses showed that expression of NRF2 mRNA and protein in KB-7D cells was 1.4 to 1.8 folds higher than those expressed in the parental cells. In addition, Chromatin Immunoprecipitation (ChIP) analysis revealed that NRF2 directly targeted to the ARE sequence in the ABCC1 promoter region. Interestingly, down-regulation of NRF2 decreased the expression of ABCC1 and also increased the chemosensitivity of KB-7D cells against selected anti-cancer drugs. In addition, cells incubated with an NRF2 activator, tBHQ, induced nucleus accumulation of NRF2 and over-expression of ABCC1, resulting in the enhancement of drug-resistance against etoposide or doxorubcin in KB and KB-7D cells. In summary, constitutive activation of NRF2-dependent ABCC1 contributed to the causation of chemoresistance in etoposide-derived drug resistant cells. Blockage of ABCC1 expression by manipulation of the NRF2 signaling pathway enhanced the chemotherapeutic efficacy in cells. Therefore, targeting NRF2 may be able to reverse chemoresistance in chemo-refractory oral malignancies. In addition, development of NRF2 inhibitors may be a new strategy to overcome chemoresistance in human cancers. (The study was supported by grants of Department of Health DOH99-TD-C-111-004, Taiwan.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1528. doi:10.1158/1538-7445.AM2011-1528

Nasopharyngeal carcinoma (NPC) is one of the predominant cancers found in Southeastern China and Taiwan. Chemotherapy is one of the major treatment modalities, and the cisplatin-based regimen is the front-line treatment. However, NPC patients failing to cisplatin treatment will have a compromised survival. To explore the resistance spectrum and mechanisms of cisplatin resistance in NPC, two cisplatin-resistant sublines (cis6 and cis15) derived from the parental NPC cell line HONE-1 were obtained. Compared with HONE-1 cells, cis6 and cis15 cells showed upto 18-fold resistance to cisplatin in each, and also possessed a cross-resistance to oxaliplatin and arsenic trioxide. The level of platinum-DNA-adduct and γH2AX were significantly decreased in cis6 and cis15 cells. To unravel the behind details, the systems of DNA repair and cisplatin detoxification were examined and found to be more active in both resistant cells. In terms of the DNA repair proteins, the levels of p-DNA-PK and XRCC1 were increased; in terms of cellular localization of cisplatin, the level of copper transporter ATP7A was upregulated; in terms of Nrf2/antioxidant/detoxifizing enzyme, the resistant cells had a higher Nrf2 activity and an increased intracellular level of GSH, GR, NQO1, AKR1C1 and AKR1C2. Moreover, as compared with HONE-1 cells, our results showed that the resistant cells spared the cisplatin-induced cell death via the suppression of pro-apoptotic proteins and the enhancement of anti-apoptotic proteins. Since the members of ErbB family could be overexpressed in NPC and the ErbB/Akt/FoxO axis could involve in the actions of apoptosis, DNA damage repair and detoxification of reactive oxygen species, the ErB/Akt/FoxO were investigated. Indeed, the phosphorylations of Akt, FoxO1, and FoxO3 were upregulated in cis6 and cis15 cells. Thus, the resistance to cisplatin in cis6 and cis15 cells was partially explained by the Akt/FoxO pathway. Surprisingly, EGFR was downregulated in the resistant cells, whereas ErbB2 was upregulated. The elevations of the negative regulators of EGFR, including c-Cbl, GCF and LRIG1, were observed in cis6 and cis15 cells, indicating that the negative regulation of EGFR could be at the levels of transcription and protein degradation. Since LRIG1 could be upregulated and negatively feedback to control the level of ErbB after the ErbB was activated, it was plausible that the overexpression of ErbB2 upregulated the expression of LRIG1 and subsequently, caused the downregulation of EGFR. Nevertheless, the hypothesis which both overexpression of ErbB2 and LRIG1 contributes to the resistance to cisplatin in our cell model awaits experimental verification. Taken together, our results suggested that the mechanism responsible for cisplatin resistance in NPC, at least in part, through Akt/FoxO pathway. (The study was supported by grants of Department of Health DOH99-TD-C-111-004, Taiwan, R.O.C.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1701. doi:10.1158/1538-7445.AM2011-1701

Cathepsin S is a vital cellular cysteine protease that is frequently amplified and over-expressed in various human cancers. In this study, we report that targeting cathpesin S could induce tumor cell autophagy via the EGFR-ERK signaling pathway. Cancer cells treated with cathepsin S inhibitors [α-ketoamide inhibitor (6r), Z-FL-COCHO (ZFL)] and cathepsin S-specific siRNA induced autophagy as indicated by an increase in the cleavage of the microtubule-associated protein light chain 3B (LC3B) and the formation of membrane-bound autophagic vacuoles (AVOs). In addition, co-treatment of a specific inhibitor of autophagy, 3-methyladenine (3MA), inhibited the 6r-induced autophagy in cancer cells. Further Western blot analysis revealed that targeting cathepsin S induced cancer cell autophagy through the activation of EGF receptor and its downstream MAPK-related signaling pathways. The induction of autophagy by targeting cathepsin S subsequently leads to the activation of apoptosis as indicated by both the up-regulation of caspase-9/3 activity, the down-regulation of Bcl-2, Bcl-XL and the altered mitochondrial membrane retention potential in cells. The application of the autophagy inhibitor, 3MA, was able to inhibit the process of apoptosis induced by the cathepsin S inhibitor 6r in cancer cells. In conclusion, the current study reveals that cathepsin S inhibitor is able to induce cancer cell autophagy through the EGF receptor signaling pathways, which may provide therapeutic benefit in cancer patients who are less sensitive to apoptosis-inducing agents. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2864. doi:10.1158/1538-7445.AM2011-2864

A series of 7-arylindoline-1-benzenesulfonamides were prepared and evaluated for anticancer activity. 7-(4′-Cyanophenyl)indoline-1-benzenesulfonamide 15 exhibited substantial antiproliferative activity with IC50 values ranging from 17–32 nM against a variety of human cancer cell lines, including MDR resistant line. Compound 15 (IC50 = 1.5 μM) also showed more potent inhibition of tubulin polymerization than 4a (combretastatin A-4, IC50 = 2.0 μM) and displayed strong binding to the colchicine binding site of the tubulin.

Background Survivin is a dual function protein. It inhibits the apoptosis of cells by inhibiting caspases, and also promotes cell growth by stabilizing microtubules during mitosis. Over-expression of survivin has been demonstrated to induce drug-resistance to various chemo-therapeutic agents such as cisplatin (DNA damaging agent) and paclitaxel (microtubule stabilizer) in cancers. However, survivin-induced resistance to microtubule de-stabilizers such as Vinca alkaloids and Combretastatin A-4 (CA-4)-related compounds were seldom demonstrated in the past. Furthermore, the question remains as to whether survivin plays a dominant role in processing cytokinesis or inhibiting caspases activity in cells treated with anti-mitotic compounds. The purpose of this study is to evaluate the effect of survivin on the resistance and susceptibility of human cancer cells to microtubule de-stabilizer-induced cell death. Results BPR0L075 is a CA-4 analog that induces microtubule de-polymerization and subsequent caspase-dependent apoptosis. To study the relationship between the expression of survivin and the resistance to microtubule de-stabilizers, a KB-derived BPR0L075-resistant cancer cell line, KB-L30, was generated for this study. Here, we found that survivin was over-expressed in the KB-L30 cells. Down-regulation of survivin by siRNA induced hyper-sensitivity to BPR0L075 in KB cells and partially re-stored sensitivity to BPR0L075 in KB-L30 cells. Western blot analysis revealed that down-regulation of survivin induced microtubule de-stabilization in both KB and KB-L30 cells. However, the same treatment did not enhance the down-stream caspase-3/-7 activities in BPR0L075-treated KB cells. Translocation of a caspase-independent apoptosis-related molecule, apoptosis-inducing factor (AIF), from cytoplasm to the nucleus was observed in survivin-targeted KB cells under BPR0L075 treatment. Conclusion In this study, survivin plays an important role in the stability of microtubules, but not with caspases inhibition. Over-expression of survivin counteracts the therapeutic effect of microtubule de-stabilizer BPR0L075 probably by stabilizing tubulin polymers, instead of the inhibition of caspase activity in cancer cells. Besides microtubule-related caspase-dependent cell death, caspase-independent mitotic cell death could be initiated in survivin/BPR0L075 combination treatments. We suggest that combining microtubule de-stabilizers with a survivin inhibitor may attribute to a better clinical outcome than the use of anti-mitotic monotherapy in clinical situations.