Jianshu Lou

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.

Abrogation of Akt signaling by Isobavachalcone contributes to its anti-proliferative effects towards human cancer cells

Akt signaling pathway has attracted much attention as a promising target for cancer therapeutics. Herein, we report that Isobavachalcone (IBC), a natural chalcone, potently abrogates Akt signaling and exerts anti-proliferative effects on several human cancer cell lines. Modeling results from the Sybyl/FlexiDock program suggest that IBC potentially binds to the ATP-binding pocket of Akt, which is confirmed by the observations that IBC inhibits Akt1 kinase in vitro. Further studies reveal that IBC significantly abates Akt phosphorylation at Ser-473 and Akt kinase activity in cells, which subsequently leads to inhibition of Akt downstream substrates and evokes significant levels of apoptosis associated with mitochondria pathway.

Simultaneous NF-κB inhibition and E-cadherin upregulation mediate mutually synergistic anticancer activity of celastrol and SAHA in vitro and in vivo.

Suberoylanilide hydroxamic acid (SAHA) is a promising histone deacetylase (HDAC) inhibitor approved by the US Food and Drug Administration (FDA) and whose clinical application for solid tumours is partially limited by decreased susceptibility in cancer cells due to nuclear factor (NF)‐κB activation. As an NF‐κB inhibitor, celastrol exhibits potent anticancer effects but has failed to enter clinical trials due to its toxicity. In this report, we demonstrated that the combination of celastrol and SAHA exerted substantial synergistic efficacy against human cancer cells in vitro and in vivo accompanied by enhanced caspase‐mediated apoptosis. This drug combination inhibited the activation of NF‐κB caused by SAHA monotherapy and consequently led to increased apoptosis in cancer cells. Interestingly, E‐cadherin was dramatically downregulated in celastrol‐resistant cancer cells, and E‐cadherin expression was closely related to decreased sensitivity to celastrol. However, our combination treatment significantly augmented the expression of E‐cadherin, suggesting that mutual mechanisms contributed to the synergistic anticancer activity. Furthermore, the enhanced anticancer efficacy of celastrol combined with SAHA was validated in a human lung cancer 95‐D xenograft model without increased toxicity. Taken together, our data demonstrated the synergistic anticancer effects of celastrol and SAHA due to their reciprocal sensitisation, which was simultaneously regulated by NF‐κB and E‐cadherin; thus, the combination of celastrol and SAHA was superior to other combination regimens that rely on a single mechanism. Our findings not only open new opportunities for the clinical development of SAHA but should also motivate the clinical investigation of celastrol, which has been hampered by its toxicity.

Synthesis and In-Vitro Antitumor Activities of Some Mannich Bases of 9-Alkyl-1,2,3,4-tetrahydrocarbazole-1-ones

A novel series of 2‐substituted aminomethyl‐9‐alkyl‐1,2,3,4‐tetrahydrocarbazole‐1‐ones 5a–q was synthesized via aminomethylation of 9‐alkyl‐1,2,3,4‐tetrahydrocarbazole‐1‐ones 4a–e with hydrochlorides of the respective amines 6a–m. The structures of these newly synthesized compounds were characterized by 1H‐NMR, MS, and elemental analysis. All the compounds were tested for their cytotoxic activity in vitro against four human tumor cell lines including human non‐small lung cancer cells (A549), human gastric adenocarcinoma (SGC), human colon cancer cell (HCT116), human myeoloid leukemia cells (K562), and one multi‐drug resistant subline (KB‐VCR). Most compounds showed moderate to potent cytotoxic activity against the tested cell lines. Preliminary mechanism research indicated that the most promising compound, 2‐diethylaminomethyl‐9‐methyl‐1,2,3,4‐tetrahydrocarbazole‐1‐one 5c, exhibited a potential inhibitory effect against microtubule.

Inhibition of all‐Trans‐retinoic acid‐induced proteasome activation potentiates the differentiating effect of retinoid in acute myeloid leukemia cells

All‐trans retinoic acid (ATRA) is nowadays considered to be the sole efficient agent for differentiation‐based therapy in leukemia; however, the mechanisms of ATRAs biological effects remain largely unknown. Here we first reported that ATRA‐induced myeloid leukemia differentiation was accompanied with the increased level of ubiquitin–protein conjugates and the upregulation of proteasome activity. To explore the functional role of the activated proteasome in retinoic acid (RA) signaling, the effects of proteasome inhibitors on RA‐induced cell differentiation were determined. Our results demonstrated that inhibition of ATRA‐elevated proteasome activity obviously promoted the myeloid maturation program triggered by ATRA, suggesting that the overactivated proteasome is not beneficial for ATRAs effects. Further studies demonstrated that the synergistic differentiating effects of ATRA and proteasome inhibitors might be associated with the protection of retinoic acid receptor alpha (RARα) from degradation by the ubiquitin–proteasome pathway (UPP). Moreover, the accumulated RARα was able to enhance the transcription of its target gene, which might also contribute to the enhanced differentiation of leukemia cells. Together, by linking the UPP to ATRA‐dependent signaling, our data provide a novel insight into studying the mechanisms of ATRA‐elicited cellular effects and imply the possibility of combination of ATRA and proteasome inhibitors in leukemia therapy. Mol. Carcinog.

Nutlin-3 inhibits epithelial–mesenchymal transition by interfering with canonical transforming growth factor-β1-Smad-Snail/Slug axis

Enormous efforts have been made to explore small molecules that interfere with the TGF-β signaling pathway, so as to inhibit EMT and the cancer metastasis, but few agents have been identified. In this study, we demonstrated that Nutlin-3 could abolish the down-regulation of E-cadherin induced by TGF-β1 in p53-deficient cancer cells. Further studies revealed that Nutlin-3 prohibited EMT by blocking the phosphorylation of Smad2/3, resulting in the decreased transcription of Snail/Slug. In addition, Nutlin-3 suppressed the motility of cancer cells, and potentiated the anti-proliferative activity of gefitinib and lapatinib. Collectively, Nutlin-3 could inhibit EMT and enhance the anti-cancer activity of EGFR inhibitors by interfering with the canonical TGF-β1-Smad-Snail/Slug axis, in a p53-independent manner.

Design, synthesis, and quantitative structure–activity relationship of cytotoxic γ-carboline derivatives

Three series of gamma-carboline derivatives were designed and synthesized. All the compounds were tested for their cytotoxic activities in vitro against five human tumor cell lines (A549, SGC, HCT116, MCF-7, K562) and one multi-drug resistant subline (K562R). Most compounds showed moderate to potent cytotoxic activities against the tested cell lines. Sulfonate 11f exhibited more potent cytotoxic activities against almost all of the tested cells in comparison with the positive control, taxol, with IC(50) values ranging from 0.15 to 4.5 microM. The structure-activity relationships were discussed and a statistically reliable QSAR model (r(2)=0.936, q(2)=0.581) was established by the CoMFA analysis performed using the cytotoxic data against K562 cell line as a template.

Design, synthesis, and biological evaluation of novel N-γ-carboline arylsulfonamides as anticancer agents.

A series of novel N-γ-carboline arylsulfonamide derivatives designed based on the common feature of colchicine binding site inhibitors were synthesized and evaluated for their antiproliferative activity in vitro against five human cancer cell lines. Most of the compounds showed moderate to potent cytotoxic activities against all the tested cells. Preliminary mechanism research on one of the most potent compound 6p indicated that it was a potent tubulin polymerization inhibitor, with IC(50) value of 3.8 μM, equivalent to that of CA-4, and arresting cell cycle in G(2)/M phase.

Inactivation of hypoxia-induced YAP by statins overcomes hypoxic resistance tosorafenib in hepatocellular carcinoma cells

Sorafenib is a multikinase inhibitor used as a first-line treatment for advanced hepatocellular carcinoma (HCC), but it has shown modest to low response rates. The characteristic tumour hypoxia of advanced HCC maybe a major factor underlying hypoxia-mediated treatment failure. Thus, it is urgent to elucidate the mechanisms of hypoxia-mediated sorafenib resistance in HCC. In this study, we found that hypoxia induced the nuclear translocation of Yes associate-Protein (YAP) and the subsequent transactivation of target genes that promote cell survival and escape apoptosis, thereby leading to sorafenib resistance. Statins, the inhibitors of hydroxymethylglutaryl-CoA reductase, could ameliorate hypoxia-induced nuclear translocation of YAP and suppress mRNA levels of YAP target genes both in vivo and in vitro. Combined treatment of statins with sorafenib greatly rescued the loss of anti-proliferative effects of sorafenib under hypoxia and improved the inhibitory effects on HepG2 xenograft tumour growth, accompanied by enhanced apoptosis as evidenced by the increased sub-G1 population and PARP cleavage. The expression levels of YAP and its target genes were highly correlated with poor prognosis and predicted a high risk of HCC patients. These findings collectively suggest that statins utilization maybe a promising new strategy to counteract hypoxia-mediated resistance to sorafenib in HCC patients.

Design, synthesis, and biological evaluation of novel γ-carboline ketones as anticancer agents

A series of novel γ-carboline ketones were designed, synthesized and evaluated for their cytotoxic activity in vitro against six human cancer cell lines (A549, SGC, HCT116, MCF-7, K562 and K562R). Biological evaluation revealed that almost all of the new compounds displayed moderate to potent cytotoxic activities against the tested cells. Among them, seven of the fourteen new compounds show more potent cytotoxic activities against K562R cell line than that of the positive control, taxol. Primary mechanism research on the most potent compound 6f indicated that it was a potent tubulin polymerization inhibitor, with IC(50) value of 4.3 μM, equivalent to that of CA-4, and arresting cell cycle in G(2)/M phase.