Honghai Wu

Insulin releasing and alpha-glucosidase inhibitory activity of ethyl acetate fraction of Acorus calamus in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE The radix of Acorus calamus L. (AC) is widely used in the therapy of diabetes in traditional folk medicine of America and Indonesia, and we previously reported the insulin sensitizing activity of the ethyl acetate fraction of AC (ACE). AIM OF THE STUDY To investigate the insulin releasing and alpha-glucosidase inhibitory activity of ACE in vitro and in vivo. MATERIALS AND METHODS Insulin releasing and alpha-glucosidase inhibitory effects of different fractions from AC were detected in vitro using HIT-T15 cell line and alpha-glucosidase enzyme. Furthermore, effects of ACE orally on serum glucose were detected in fasted and glucose/amylum challenged normal mice. RESULTS AC and ACE increased insulin secretion in HIT-T15 cells as gliclazide did. As in vivo results, ACE (400 and 800 mg/kg) significantly decreased fasting serum glucose, and suppressed the increase of blood glucose levels after 2g/kg glucose loading in normal mice. In addition, ACE as a mixed-type inhibitor inhibited alpha-glucosidase activity in vitro with an IC(50) of 0.41 microg/ml, and 100mg/kg of it clearly reduced the increase of blood glucose levels after 5 g/kg amylum loading in normal mice. CONCLUSIONS Apart from its insulin sensitizing effect, ACE may have hypoglycemic effects via mechanisms of insulin releasing and alpha-glucosidase inhibition, and thus improves postprandial hyperglycemia and cardiovascular complications.

Oxidative stress is involved in Dasatinib-induced apoptosis in rat primary hepatocytes

Dasatinib, a multitargeted inhibitor of BCR-ABL and SRC kinases, exhibits antitumor activity and extends the survival of patients with chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL). However, some patients suffer from hepatotoxicity, which occurs through an unknown mechanism. In the present study, we found that Dasatinib could induce hepatotoxicity both in vitro and in vivo. Dasatinib reduced the cell viability of rat primary hepatocytes, induced the release of alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) in vitro, and triggered the ballooning degeneration of hepatocytes in Sprague-Dawley rats in vivo. Apoptotic markers (chromatin condensation, cleaved caspase-3 and cleaved PARP) were detected to indicate that the injury induced by Dasatinib in hepatocytes in vitro was mediated by apoptosis. This result was further validated in vivo using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays. Here we found that Dasatinib dramatically increased the level of reactive oxygen species (ROS) in hepatocytes, reduced the intracellular glutathione (GSH) content, attenuated the activity of superoxide dismutase (SOD), generated malondialdehyde (MDA), a product of lipid peroxidation, decreased the mitochondrial membrane potential, and activated nuclear factor erythroid 2-related factor 2 (Nrf2) and mitogen-activated protein kinases (MAPK) related to oxidative stress and survival. These results confirm that oxidative stress plays a pivotal role in Dasatinib-mediated hepatotoxicity. N-acetylcysteine (NAC), a typical antioxidant, can scavenge free radicals, attenuate oxidative stress, and protect hepatocytes against Dasatinib-induced injury. Thus, relieving oxidative stress is a viable strategy for reducing Dasatinib-induced hepatotoxicity.

GDC-0941 sensitizes breast cancer to ABT-737 in vitro and in vivo through promoting the degradation of Mcl-1

The present study showed that GDC-0941 potently sensitized breast cancer to ABT-737 in vitro and in vivo. ABT-737 exhibited limited lethality in breast cancer cells; however, when combined with GDC-0941, it displayed strong synergistic cytotoxicity and enhanced caspase-mediated apoptosis. GDC-0941 promoted proteasomal degradation of Mcl-1, of which the overexpression has been validated to confer ABT-737 resistance, thereby enhanced the anticancer efficacy of ABT-737. Furthermore, the combination of GDC-0941 and ABT-737 exerted increased anti-tumor efficacy on MDA-MB-231 xenograft models. Overall, our data described unprecedentedly the promising therapeutic potential and underlying mechanisms of combining GDC-0941 with ABT-737 in treating breast cancer.

Metformin prevents cancer metastasis by inhibiting M2-like polarization of tumor associated macrophages

Accumulated evidence suggests that M2-like polarized tumor associated macrophages (TAMs) plays an important role in cancer progression and metastasis, establishing TAMs, especially M2-like TAMs as an appealing target for therapy intervention. Here we found that metformin significantly suppressed IL-13 induced M2-like polarization of macrophages, as illustrated by reduced expression of CD206, down-regulation of M2 marker mRNAs, and inhibition of M2-like macrophages promoted migration of cancer cells and endothelial cells. Metformin triggered AMPKα1 activation in macrophage and silencing of AMPKα1 partially abrogated the inhibitory effect of metformin in IL-13 induced M2-like polarization. Administration of AICAR, another activator of AMPK, also blocked the M2-like polarization of macrophages. Metformin greatly reduced the number of metastases of Lewis lung cancer without affecting tumor growth. In tumor tissues, the percentage of M2-like macrophage was decreased and the area of pericyte-coated vessels was increased. Further, the anti-metastatic effect of metformin was abolished when the animals were treated with macrophages eliminating agent clodronate liposome. These findings suggest that metformin is able to block the M2-like polarization of macrophages partially through AMPKα1, which plays an important role in metformin inhibited metastasis of Lewis lung cancer.

BZYX, a novel acetylcholinesterase inhibitor, significantly improved chemicals-induced learning and memory impairments on rodents and protected PC12 cells from apoptosis induced by hydrogen peroxide.

BZYX was designed as a dual-binding-site acetylcholinesterase (AChE) inhibitor and selected from series of indanone derivatives. The present study was designed to examine the cognition-enhanced, anti-cholinesterase, and neuroprotective effects of BZYX. In the passive avoidance performance and radial arm maze, BZYX showed a comparable effect to donepezil and rivastigmine on memory deficits in different stages induced by scopolamine, NaNO(2) and ethanol, respectively. Ellmans assay indicated BZYX exhibited high inhibition on AChE activity. IC(50) values for BZYX: 0.058+/-0.022 microM; donepezil: 0.019+/-0.004 microM; rivastigmine: 3.81+/-2.81 microM; glantamine: 3.01+/-1.85 microM and huperzine A: 0.053+/-0.016 microM. BZYX also presented great neuroprotecive function from apoptosis induced by hydrogen peroxide(H(2)O(2)) in PC12 cells. MTT assay and Annexin V-FITC Apoptosis Detection showed the viability of PC12 cells remarkably decreased with 400 microM H(2)O(2), while it significantly increased when the cells were pretreated with 0.1-1.0 microM BZYX. BZYX pretreatment remarkably reversed the loss of mitochondria membrane potential (DeltaPsim), scavenged reactive oxygen species formation induced by H(2)O(2) and resulted in up-regulation of procaspase3 and xIAP protein level and down-regulation of phosphorylated JNK protein, p53 protein level and cleavage of caspase 3. It is speculated that the mitochondrial pathway, mediated by Bcl-2 family and Mitogen-Activated Protein Kinases (MAPKs), might involved in the neuroprotection of BZYX. These results first demonstrated that BZYX had neuroprotective effects as well as cognition enhancement and acetylcholinesterase inhibition. It is hopeful that BZYX becomes a potential candidate for use in the intervention for neurodegenerative diseases.

Q39, a quinoxaline 1,4-Di-N-oxide derivative, inhibits hypoxia-inducible factor-1α expression and the Akt/mTOR/4E-BP1 signaling pathway in human hepatoma cells

SummaryCumulative evidence has established that hypoxia-inducible factor-1α (HIF-1α) and its downstream target, vascular endothelial growth factor (VEGF), play a critical role in hepatocellular carcinoma angiogenesis, invasiveness and metastasis. 3-(4-bromophenyl)-2-(ethylsulfonyl)-6-methylquinoxaline 1,4-dioxide (Q39) has recently shown great antiproliferative activity in extensive cell lines in normoxia and hypoxia. In this study, Q39 exhibited high antiproliferative activity against hepatoma both in vitro and in vivo, mainly by inducing apoptosis. In addition, suppression of HIF-1α by Q39 resulted in a drastic decrease in VEGF expression. These results indicate that Q39 is an effective inhibitor of HIF-1α and provide new perspectives into the mechanism of its anticancer activity. Interestingly, neither the HIF-1α degradation rate nor the HIF-1α steady-state mRNA level was affected by Q39. Instead, suppression of HIF-1α accumulation by Q39 correlated with prominent dephosphorylation of mTOR and 4E-BP1, a pathway known to regulate protein expression at the translational level.

Autophagy blockade sensitizes the anticancer activity of CA-4 via JNK-Bcl-2 pathway

Combretastatin A-4 (CA-4) has already entered clinical trials of solid tumors over ten years. However, the limited anticancer activity and dose-dependent toxicity restrict its clinical application. Here, we offered convincing evidence that CA-4 induced autophagy in various cancer cells, which was demonstrated by acridine orange staining of intracellular acidic vesicles, the degradation of p62, the conversion of LC3-I to LC3-II and GFP-LC3 punctate fluorescence. Interestingly, CA-4-mediated apoptotic cell death was further potentiated by pretreatment with autophagy inhibitors (3-methyladenine and bafilomycin A1) or small interfering RNAs against the autophagic genes (Atg5 and Beclin 1). The enhanced anticancer activity of CA-4 and 3-MA was further confirmed in the SGC-7901 xenograft tumor model. These findings suggested that CA-4-elicited autophagic response played a protective role that impeded the eventual cell death while autophagy inhibition was expected to improve chemotherapeutic efficacy of CA-4. Meanwhile, CA-4 treatment led to phosphorylation/activation of JNK and JNK-dependent phosphorylation of Bcl-2. Importantly, JNK inhibitor or JNK siRNA inhibited autophagy but promoted CA-4-induced apoptosis, indicating a key requirement of JNK-Bcl-2 pathway in the activation of autophagy by CA-4. We also identified that pretreatment of Bcl-2 inhibitor (ABT-737) could significantly enhance anticancer activity of CA-4 due to inhibition of autophagy. Taken together, our data suggested that the JNK-Bcl-2 pathway was considered as the critical regulator of CA-4-induced protective autophagy and a potential drug target for chemotherapeutic combination.

SAHA triggered MET activation contributes to SAHA tolerance in solid cancer cells

Although SAHA is approved for the treatment of cutaneous T-cell lymphoma by the U.S. Food and Drug Administration, clinical trials using SAHA as a monotherapy or in combination with other chemotherapeutic agents in solid tumors have not met with success, and the mechanisms of tolerance remain unknown. In this study, using the prostate cancer cell line PC3 and the non-small lung cancer cell line A549, which have limited sensitivity to SAHA, we found that SAHA triggered MET and AKT phosphorylation at clinical concentrations. siRNA silencing of MET enhanced SAHA induced apoptosis in PC3 and A549 cells. However, MET protein expression and HGF secretion were not affected by SAHA, suggesting that the SAHA-induced MET activation was not due to MET over-expression or HGF paracrine secretion. However, mRNA and protein expression of the laminin receptor integrin α5β1 was up-regulated by SAHA prior to MET activation. Silencing of integrin α5β1 abolished SAHA-triggered MET phosphorylation, suggesting the involvement of integrin α5β1 in MET activation. Further, the combination of SAHA and XL184 resulted in a synergistic induction of cancer cell apoptosis and a synergistic inhibition of tumor growth. These data indicate that SAHA triggered MET activation in an HGF independent manner. This effect is partially involved in the resistance to SAHA in solid cancers, warranting further clinical investigation into combining SAHA with MET inhibitors in solid cancer treatment.

A novel indole derivative compound GY3 improves glucose and lipid metabolism via activation of AMP-activated protein kinase pathway

The AMP-activated protein kinase (AMPK) is a ubiquitously expressed serine/threonine protein kinase that functions as an intracellular fuel sensor. It has been demonstrated to mediate the activities of a number of pharmacological and physiological factors that exert beneficial effects on type2 diabetes mellitus. GY3 is a novel synthesized indole compound derived from indomethacin, a non-steroid anti-inflammatory drug. In a previous study, we found that GY3 could improve insulin resistance and lower glucose levels in db/db mice, although its mechanism of action is not yet clear. In this study, we demonstrate that in vivo administration of GY3 improved serum triglyceride levels and decreased lipid accumulation in the livers of db/db mice. In vitro studies show that GY3 increased glucose consumption in HepG2 cells and 3T3-L1 adipocytes, decreased free fatty acid (FFA)-induced lipid accumulation in HepG2 cells and lipid accumulation in 3T3-L1 adipocytes. In vitro studies further show that GY3 improved glucose and lipid metabolism through an AMPK-dependent pathway but not the PI3K pathway. These findings suggest that GY3 is an effective agent for the improvement of glucose and lipid metabolism through AMPK pathway activation.

Synergistic effects of DL111-IT in combination with mifepristone and misoprostol on termination of early pregnancy in preclinical studies

This study evaluated the effectiveness and acute toxicity of DL111-IT combined with mifepristone (RU486) and misoprostol (MISO) on early pregnancy termination. In the pregnant rats experiments, the ED(50) values of RU486 in two-drug combinations were 0.16 (combined with DL111-IT) and 0.40 (combined with MISO) mg x kg(-1) x d(-1), while in three-drug combination treatment group (DL111-IT 9.0 mg x kg(-1) (<ED(5)) + MISO 0.30 mg x kg(-1) + RU486 0.012-0.5 mg x kg(-1) x d(-1)), the ED(50) of RU486 was decreased to 0.07 (0.04-0.10) mg x kg(-1) x d(-1). In guinea pigs, significant enhancement of early pregnancy termination was only observed in three-drug combination treatment with MISO 0.10 mg x kg(-1) + RU486 0.05 mg x kg(-1) (<minimum effective doses) + high dosages of DL111-IT (0.05-0.10 mg x kg(-1)). DL111-IT induced pregnant rat uterine contraction in vitro, and the contractive efficacy was 60% of that induced by MISO. Multiple intramuscular injections of DL111-IT in vivo could significantly enhance the MISO-stimulated uterine contractions of pregnant rats in vitro. DL111-IT 600 mg x kg(-1) or RU486 1000 mg x kg(-1) induced pigeon vomiting, with latent periods of 32.3 +/- 12.0 min and 50.4 +/- 16.0 min, respectively. In three-drug combination group, the latent period of vomiting was significantly extended to 86.3 +/- 36.2 min. MISO also significantly decreased the frequency of vomiting within 4 h after administration of DL111-IT and RU486. In the experiment of mice acute toxicity, the LD(50) values and 95% confidence limit of DL111-IT (i.p.) alone and in combination with RU486 and MISO were 1379.4 (1278.2-1514.7) mg x kg(-1) and 1574.1 (1407.8-1762.7) mg x kg(-1), respectively. There was no significant difference. All data suggested that DL111-IT in combination with RU486 and MISO significantly increased the effect on early pregnancy termination without increasing acute toxicity compared to the treatment of DL111-IT alone, and this combination may be a promising regimen for early pregnancy termination.