Judy Yuet-Wa Chan

In vivo reversal of general anesthesia by cucurbit[7]uril with zebrafish models

A general anesthetic is a drug that brings about a reversible loss of consciousness, during a surgical or therapeutic procedure to render the patient free of pain and anxiety. However, the effect of anesthetics may linger far beyond the necessary time required and induce adverse effects. In addition, many surgical patients need to recover to a conscious state that allows them to make important decisions soon after their surgery. Unfortunately, there are currently no clinically-available anti-dotes to reverse the effects of anesthetics. In this study, we demonstrate the in vitro supramolecular host–guest complexations between macrocyclic cucurbit[7]uril (CB[7]) and a commonly used general anesthetic in fish, tricaine mesylate (TM), and we report for the first time the in vivo reversal effect of CB[7] to general anesthesia induced by TM with zebrafish models. These findings might lead to a new approach that may allow patients to regain lucidity much faster than their natural recovery from general anesthesia, and may also be used to reverse potentially life-threatening toxic effects encountered by some patients in response to general anesthesia.

Developmental and organ-specific toxicity of cucurbit(7)uril: in vivo study on zebrafish models†

The macrocyclic molecular container cucurbit[7]uril (CB[7]), the most water-soluble homologue in the cucurbit[n]uril family (n = 5–8, 10, 14), has been evaluated for its in vivo toxicity profile, including its developmental toxicity such as its effect on hatching, growth and survival, as well as its potential organ-specific toxicities such as cardiotoxicity, hepatotoxicity, and locomotion and behavioral toxicity, using zebrafish models. The results revealed that CB[7] has measureable cardiotoxicity and locomotion and behavioral toxicity at concentrations of ∼500 μM or higher, and negligible developmental and hepatotoxicity at concentrations up to 750 μM, although extended exposure to CB[7] in the 500–750 μM concentration range induced the mortality of tested fish. These results demonstrate for the first time with live in vivo animal models that CB[7] has relatively low developmental and organic specific toxicity, and support further exploration of the use of CB[7] in biomedical research at sub-toxic concentrations.

A novel agent exerts antitumor activity in breast cancer cells by targeting mitochondrial complex II

The mitochondrial respiratory chain, including mitochondrial complex II, has emerged as a potential target for cancer therapy. In the present study, a novel conjugate of danshensu (DSS) and tetramethylpyrazine (TMP), DT-010, was synthesized. Our results showed that DT-010 is more potent than its parental compounds separately or in combination, in inhibiting the proliferation of MCF-7 and MDA-MB-231 cells by inducing cytotoxicity and promoting cell cycle arrest. It also inhibited the growth of 4T1 breast cancer cells in vivo. DT-010 suppressed the fundamental parameters of mitochondrial function in MCF-7 cells, including basal respiration, ATP turnover, maximal respiration. Treatment with DT-010 in MCF-7 and MDA-MB-231 cells resulted in the loss of mitochondrial membrane potential and decreased ATP production. DT-010 also promoted ROS generation, while treatment with ROS scavenger, NAC (N-acetyl-L-cysteine), reversed DT-010-induced cytotoxicity. Further study showed that DT-010 suppressed succinate-induced mitochondrial respiration and impaired mitochondrial complex II enzyme activity indicating that DT-010 may inhibit mitochondrial complex II. Overall, our results suggested that the antitumor activity of DT-010 is associated with inhibition of mitochondrial complex II, which triggers ROS generation and mitochondrial dysfunction in breast cancer cells.

SAR studies of 3,14,19-derivatives of andrographolide on anti-proliferative activity to cancer cells and toxicity to zebrafish: an in vitro and in vivo study

Andrographolide is bestowed with an interesting pharmacophore and has attracted numerous studies on the design and synthesis of andrographolide derivatives. In this study, a small library of 3,14,19-modified derivatives of andrographolide were synthesized and tested for their in vitro inhibitory activities to cancer cell growth and proliferation and in vivo toxicities against zebrafish embryo development. Structure anti-proliferative activity and toxicity relationships in current data revealed that the property of a substituent, substituted positions, and 14-stereochemistry together determined a compounds in vitro anti-proliferative activity against cancer cells, the in vivo toxicity to zebrafish, and the selectivity between MDA-MB-231 and A549. Taken together, our SAR studies discovered some potential leads for further development of anticancer drugs and suggested that the direct and/or indirect toxicity of an active compound with andrographolide pharmacophore should be given attention.

A Novel Danshensu Derivative Prevents Cardiac Dysfunction and Improves the Chemotherapeutic Efficacy of Doxorubicin in Breast Cancer Cells.

Doxorubicin (Dox) is an anthracycline antibiotic widely used in clinics as an anticancer agent. However, the use of Dox is limited by its cardiotoxicity. We have previously shown that a Danshensu (DSS) derivative, ADTM, displayed strong cardioprotective effects. With improved chemical stability and activity, a novel DSS derivative, D006, based on the structure of ADTM, was synthesized. In the present study, the protective effects of D006, indexed by attenuation of the cardiotoxicity induced by Dox as well as chemosensitizing effects that increase the antitumor activity of Dox, were investigated. Our results showed that D006 was more potent than either parental compound, or their use in combination, in ameliorating Dox‐induced toxicity in H9c2 cells. In our zebrafish model, D006, but not DSS, alone significantly preserved the ventricular function of zebrafish after Dox treatment. Moreover, D006 upregulated mitochondrial biogenesis and increased mtDNA copy number after Dox treatment of H9c2 cells. D006 promoted the expression of HO‐1 protein in a time‐dependent manner while the HO‐1 inhibitor, Znpp, reversed the protective effects of D006. In human breast tumor MCF‐7 cells, D006 enhanced Dox‐induced cytotoxicity by increasing apoptosis. In conclusion, our results indicate that a new DSS derivative exhibits promising protective effects against Dox‐induced cardiotoxicity both in vivo and in vitro, an effect at least partially mediated by induction of HO‐1 expression and the activation of mitochondrial biogenesis. Meanwhile, D006 also potentiated the anti‐cancer effects of Dox in breast tumor cells. J. Cell. Biochem. 117: 94–105, 2016.

Rhodamine B-conjugated encrypted vipericidin nonapeptide is a potent toxin to zebrafish and associated with in vitro cytotoxicity

BACKGROUND Animal venoms contain a diverse array of proteins and enzymes that are toxic toward various physiological systems. However, there are also some practical medicinal uses for these toxins including use as anti-bacterial and anti-tumor agents. METHODS In this study, we identified a nine-residue cryptic oligopeptide, KRFKKFFKK (EVP50) that is repeatedly encoded in tandem within vipericidin sequences. RESULTS EVP50 displayed in vivo potent lethal toxicity to zebrafish larvae (LD50=6 μM) when the peptides N-terminus was chemically conjugated to rhodamine B (RhoB). In vitro, RhoB-conjugated EVP50 (RhoB-EVP50) exhibited a concentration-dependent cytotoxic effect toward MCF-7 and MDA-MB-231 breast cancer cells. In MCF-7 cells, the RhoB-EVP50 nonapeptide accumulated inside the cells within minutes. In the cytoplasm, the RhoB-EVP50 induced extracellular calcium influx and intracellular calcium release. Membrane budding was also observed after incubation with micromolar concentrations of the fluorescent EVP50 conjugate. CONCLUSIONS The conjugates interference with calcium homeostasis, its intracellular accumulation and its induced membrane dysfunction (budding and vacuolization) seem to act in concert to disrupt the cell circuitry. Contrastively, unconjugated EVP50 peptide did not display neither toxic nor cytotoxic activities in our in vivo and in vitro models. GENERAL SIGNIFICANCE The synergic mechanism of toxicity was restricted to the structurally modified encrypted vipericidin nonapeptide.

Anti-angiogenic activity of a new andrographolide derivative in zebrafish and HUVECs

Andrographolide is among the most promising anti-tumor and anti-angiogenic components in Andrographis paniculata but its poor bioavailability and limited efficacy pose difficulties for its therapeutic development. Therefore, improving its pharmaceutical features and potency, by modifying its chemical structure, is desirable. In the present study, a new andrographolide derivative (AGP-40) was synthesized and characterized for its anti-angiogenic properties. Human umbilical vein endothelial cells (HUVECs) and zebrafish models were used to identify the anti-angiogenic activity of AGP-40. AGP-40 significantly suppressed the formation of blood vessels in zebrafish and inhibited proliferation, migration and tube formation in vitro. The anti-angiogenic effects of AGP-40 are at least partially mediated via the PI3K/Akt and MEK/Erk(1/2) signaling pathways. Furthermore, AGP-40 exhibited stronger anti-proliferative effects than andrographolide against A549, HepG2, Hela cancer cell lines. This study is the first to demonstrate the promising anti-angiogenic activity of the new andrographolide derivative AGP-40. Our results indicate that AGP-40 could serve as a potential therapeutic agent for the treatment and prevention of diseases associated with excessive angiogenesis.

New perspective on the dual functions of indirubins in cancer therapy and neuroprotection.

Indirubin is an active ingredient mainly used to treat leukemia in China and is reported to be a leading inhibitor of cyclindependent kinases (CDKs) and glycogen synthase kinase-3 (GSK-3) by competing with ATP binding sites. New findings have indicated that its comprehensive structure may contribute to its polypharmacological activities particularly in cancer and neurodegenerative disease therapy, as both of these diseases are usually accompanied by a common molecular link related to abnormal phosphorylation of CDKs and GSK-3. In the elderly, cancer and neurodegenerative disease are tightly associated common diseases and sometimes unavoidably coexist. In this review, the underlying mechanisms of the dual actions of indirubin and its structurally-related compounds in cancer and neurodegenerative disease therapy are presented.

A Novel Agent Enhances the Chemotherapeutic Efficacy of Doxorubicin in MCF-7 Breast Cancer Cells

We have previously demonstrated that DT-010, a novel conjugate of danshensu (DSS) and tetramethylpyrazine (TMP), displays anti-tumor effects in breast cancer cells both in vitro and in vivo. In the present study, we investigated whether DT-010 enhances the chemotherapeutic effect of doxorubicin (Dox) in MCF-7 breast cancer cells and exerts concurrent cardioprotective benefit at the same time. Our findings showed that DT-010 was more potent than TMP, DSS, or their combination in potentiating Dox-induced toxicity in MCF-7 cells. Co-treatment with DT-010 and Dox increased apoptosis in MCF-7 cells relative to Dox alone. Further study indicated that glycolytic capacity, glycolytic reserve and lactate level of MCF-7 cells were significantly inhibited after DT-010 treatment. DT-010 also increased the expression of the pro-survival protein GRP78, which was inhibited by co-treatment with Dox. Both endoplasmic reticulum stress inhibitor 4-PBA and knockdown of the expression of GRP78 protein potentiated DT-010-mediated apoptosis in MCF-7 cells. Moreover, DT-010 inhibited Dox-induced cardiotoxicity in H9c2 myoblasts. In conclusion, DT-010 and Dox confer synergistic anti-tumor effect in MCF-7 breast cancer cells through downregulation of the glycolytic pathway and inhibition of the expression of GRP78. Meanwhile, DT-010 also protects against Dox-induced cardiotoxicity.

Synergistic effect of fenretinide and curcumin for treatment of non-small cell lung cancer

ABSTRACT Curcumin and fenretinide are 2 well-known and promising chemotherapeutic compounds via various molecular mechanisms. However, the anticancer capacity of either curcumin or fenretinide is limited. This prompted us to examine the combined anticancer effects of curcumin and fenretinide. Our results demonstrate for the first time that there is synergistic anticancer effect of combined treatment with these 2 agents, leading to enhanced cytotoxicity and enhanced expression level of pro-apoptotic protein cleaved PARP in non-small cell lung cancer (NSCLC) cells while showed little toxicity to rat cardiomyoblast normal cells. The combination treatment was also demonstrated to inhibit lung carcinoma growth in vivo. Furthermore, we show that fenretinide or the ER stress inhibitor 4-PBA decreased curcumin-induced Glucose-regulated protein 78 (GRP78) upregulation, and produced a similar enhanced cytotoxic effect. In addition, GRP78 knockdown by siRNA also enhanced the cytotoxic effect of curcumin in A549 and H1299 cells. Our findings suggest that the 2 small molecules, when used in combination, can potentially be effective therapeutic agents for treating NSCLC, at least in part, by regulating endoplasmic reticulum (ER) chaperone protein GRP78.