Hong-Mei Zheng

Melatonin ameliorates cerulein‐induced pancreatitis by the modulation of nuclear erythroid 2‐related factor 2 and nuclear factor‐kappaB in rats

Abstract:  Melatonin exhibits a wide variety of biological effects, including antioxidant and anti‐inflammatory functions. Its antioxidant role impedes the etiopathogenesis of pancreatitis, but little is known about the signaling pathway of melatonin in the induction of antioxidant enzymes in acute pancreatitis (AP). The aim of this study was to determine whether melatonin could prevent cerulein‐induced AP through nuclear factor erythroid 2‐related factor 2 (Nrf2) and curtail inflammation by inhibition of NF‐κB. AP was induced by two intraperitoneal (i.p.) injections of cerulein at 2 h intervals (50 μg/kg) in Sprague‐Dawley rats. Melatonin (10 or 50 mg/kg/daily, i.p.) was administered 24 h before each injection of cerulein. The rats were killed 12 h after the last injection. Acinar cell degeneration, pancreatic edema, and inflammatory infiltration were significantly different in cerulein‐ and melatonin‐treated rats. Melatonin significantly reduced amylase, lipase, MPO, and MDA levels, and increased antioxidant enzyme activities including SOD and GPx, which were decreased in AP (P < 0.05). Melatonin increased the expression of NQO1, HO‐1, and SOD2 when compared with the cerulein‐induced AP group (P < 0.05). In addition, melatonin increased Nrf2 expression, and reduced expressions of tumor necrosis factor‐alpha, IL‐1β, IL‐6, IL‐8, and iNOS. The elevated nuclear binding of NF‐κB in the cerulein‐induced pancreatitis group was inhibited by melatonin. These results show that melatonin increases antioxidant enzymes and Nrf2 expression, and limits inflammatory mediators in cerulein‐induced AP. It is proposed that melatonin may play an important role in oxidative stress via the Nrf2 pathway in parallel with reduction of inflammation by NF‐κB inhibition.

Melatonin downregulates nuclear erythroid 2-related factor 2 and nuclear factor-kappaB during prevention of oxidative liver injury in a dimethylnitrosamine model

Abstract:  Melatonin has potent hepatoprotective effects as an antioxidant. However, the signaling pathway of melatonin in the induction of antioxidant enzymes against acute liver injury is not fully understood. The study aimed to determine whether melatonin could prevent dimethylnitrosamine (DMN)‐induced liver injury through nuclear erythroid 2‐related factor 2 (Nrf2) and inflammation. Liver injury was induced in rats by a single injection of DMN (30 mg/kg, i.p.). Melatonin treatment (50 mg/kg/daily, i.p.) was initiated 24 hr after DMN injection for 14 days, after which the rats were killed and samples were collected. Serum and antioxidant enzyme activities improved in melatonin‐treated rats, compared with DMN‐induced liver injury group (P < 0.01). Melatonin reduced the infiltration of inflammatory cells and necrosis in the liver, and increased the expression of NADPH: quinone oxidoreductase‐1, heme oxygenase‐1, and superoxide dismutase‐2, which were decreased by DMN. Melatonin increased expression of novel transcription factor, Nrf2, and decreased expression of inflammatory mediators including tumor necrosis factor‐alpha, interleukin (IL)‐1β, IL‐6, and inducible nitric oxide synthase. The increased nuclear binding of nuclear factor‐kappa B (NF‐κB) in the DMN‐induced liver injury group was inhibited by melatonin. Our results show that melatonin increases antioxidant enzymes and Nrf2 expression in parallel with the decrease of inflammatory mediators in DMN‐induced liver injury, suggesting that melatonin may play a role of antioxidant defense via the Nrf2 pathway, by reducing inflammation by NF‐κB inhibition.

Porous silicon nanoparticles for cancer photothermotherapy

The in vitro cell tests and in vivo animal tests were performed to investigate the feasibility of the photothermal therapy based on porous silicon (PSi) in combination with near-infrared (NIR) laser. According to the Annexin V- fluorescein isothiocyanate Apoptosis assay test results, the untreated cells and the cells exposed to NIR laser without PSi treatment had a cell viability of 95.6 and 91.3%, respectively. Likewise, the cells treated with PSi but not with NIR irradiation also had a cell viability of 74.4%. Combination of these two techniques, however, showed a cell viability of 6.7%. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results showed that the Murine colon carcinoma (CT-26) tumors were completely resorbed without nearly giving damage to surrounding healthy tissue within 5 days of PSi and NIR laser treatment. Tumors have not recurred at all in the PSi/NIR treatment groups thereafter. Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

The protective effect of resveratrol on dimethylnitrosamine-induced liver fibrosis in rats.

Oxidative stress in liver injury is a major pathogenetic factor in progress of liver fibrosis. Resveratrol, a representative antioxidant derived from grapes, has been reported to show widespread pharmacological properties. In this study, we investigated the protective effects of resveratrol on dimethylnitrosamine (DMN)-induced liver fibrosis in rats. Rats were treated with resveratrol daily by oral gavage for seven days after a single intraperitoneal injection of DMN (40 mg/kg). Resveratrol remarkably recovered body and liver weight loss due to DMNinduced liver fibrosis. Liver histology showed that resveratrol alleviated the infiltration of inflammatory cells and fibrosis of liver tissue. Resveratrol decreased the level of malondialdehyde and increased the levels of glutathione peroxidase and superoxide dismutase. Also, resveratrol significantly inhibited the mRNA expression of inflammatory mediators including inducible nitric oxide, tumor necrosis factor-alpha and interleukin-1beta. In addition, resveratrol showed not only reduced mRNA expression of fibrosis-related genes such as transforming growth factor beta 1, collagen type I, and alpha-smooth muscle actin, but also a significant decrease of hydroxyproline in rats with DMN-induced liver fibrosis. Our results suggest that resveratrol could be used to treat liver injury and fibrosis and be useful in preventing the development of liver fibrosis and cirrhosis.

Suppression by fucoidan of liver fibrogenesis via the TGF-β/Smad pathway in protecting against oxidative stress.

Fucoidan, a sulfated polysaccharide extracted from various types of brown seaweed, possesses a wide range of pharmacological properties. We investigated the protective effect of fucoidan on dimethylnitrosamine-induced liver fibrogenesis in rats and its mechanism. Liver fibrosis was induced by injecting DMN (10 mg/kg, 3 times per week, I.P.) for 4 weeks, and fucoidan was simultaneously administered (100 mg/kg, 3 times per week, P.O.). The anti-oxidative and anti-inflammatory effects of fucoidan were observed by relative mediators. Fucoidan improved liver fibrosis by inhibiting the expression of transforming growth factor beta 1 (TGF-β1)/Smad3 and the tissue inhibitor of metalloproteinase 1 (TIMP-1), and increasing the expression of metalloproteinase-9 (MMP-9). Fucoidan also significantly decreased the accumulation of the extracellular matrix (ECM) and collagen. These results suggest that fucoidan had an anti-fibrotic effect, which was exerted by inhibiting the TGF-β/Smad pathway, as well as anti-oxidative and anti-inflammatory effects.

SB365 inhibits angiogenesis and induces apoptosis of hepatocellular carcinoma through modulation of PI3K/Akt/mTOR signaling pathway

Identification of small molecules that safely inhibit cancer progression is critical for cancer therapeutics. Saponins exhibit cytostatic and cytotoxic activity against various cancer cells, but the mechanism is not well understood. Here, we investigated whether saponin D (designated SB365), an active component isolated from Pulsatilla koreana, could inhibit the progression of hepatocellular carcinoma (HCC) and considered its mechanism. SB365 strongly suppressed the growth of HCC cells in a dose‐dependent manner and induced apoptosis by increasing the proportion of sub G1 apoptotic cells from 8% to 21% through induction of expression of Bax and cleaved caspase‐3. In addition, SB365 exhibited potent anti‐angiogenic activity and decreased the expression of hypoxia‐inducible factor‐1α (HIF‐1α) and vascular endothelial growth factor, a key molecule for angiogenesis. Furthermore, SB365 suppressed the tube formation and migration of HUVEC, as well as in vivo neovascularization in a mouse Matrigel plug assay. In vivo study showed that SB365 significantly inhibited tumor growth in an HCC xenograft model, inducing apoptosis by increasing the expression of the cleaved caspase‐3 and DNA fragmentation. The expressions of vascular endothelial growth factor and CD34 in the tumor tissue were decreased by SB365 treatment. In examining its mechanism, SB365 was found to effectively suppress the phosphorylation of PI3K downstream factors, such as Akt, mTOR and p70S6K both in vitro and in vivo. Our study demonstrates that SB365 not only induces apoptosis but also inhibits cell growth and angiogenesis through modulation of the PI3K/Akt/mTOR pathway in human HCC. We suggest that SB365 may be a new chemotherapeutic candidate against HCC.

HS-116, a novel phosphatidylinositol 3-kinase inhibitor induces apoptosis and suppresses angiogenesis of hepatocellular carcinoma through inhibition of the PI3K/AKT/mTOR pathway

The phosphatidylinositol 3-kinase (PI3K) pathway plays a central role in cell proliferation and survival of human cancers. As PI3K is active in many cancer patients, resulting in cancer development and progression, we developed an azaindole derivative, HS-116 as a novel PI3K inhibitor. This study aimed to clarify the anticancer effect of HS-116 in human hepatocellular carcinoma (HCC). To identify the effect of HS-116 on HCC cells, a PI3K assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, and Western blotting were conducted. IC(50) of HS-116 for PI3Kα was 31nM, and it effectively suppressed the phosphorylation of PI3K downstream factors such as AKT, mTOR, p70S6K, and 4EBP1. Also, HS-116 induced apoptosis by increasing the proportion of sub-G1 apoptotic cells from 1.8% to 35% and increasing the expressions of Bax, cleaved-caspase-3, and cleaved-PARP as well as decreasing the expression of Bcl-2. In addition, chromatin condensation and apoptotic bodies were detected in HS-116-treated HCC cells. Furthermore, HS-116 decreased protein expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF), and inhibited the tube formation and migration of human umbilical vein endothelial cells (HUVECs). In vivo, the ability of mice to vascularize subcutaneously implanted Matrigel plugs was diminished when the mice were treated with HS-116. These results show that HS-116 inhibits the PI3K/AKT/mTOR pathway via apoptosis and anti-angiogenesis in HCC cells. We suggest that HS-116 may be an effective novel therapeutic candidate against HCC.

SB365, Pulsatilla saponin D suppresses the proliferation of human colon cancer cells and induces apoptosis by modulating the AKT/mTOR signalling pathway

Pulsatilla koreana has been used as a traditional medicine for the treatment of several diseases. The purpose of this study was to determine if SB365, Pulsatilla saponin D isolated from the root of P. koreana inhibits the progression of colon cancer. We found that SB365 strongly suppressed the growth and proliferation of colon cancer cells and induced their apoptosis. Also, SB365 showed anti-angiogenic activity by decreasing the expression of HIF-1α and VEGF. These results were confirmed by an in vivo study showing that SB365 significantly inhibited tumor growth by the induction of apoptosis and inhibition of angiogenesis with stronger anticancer activity than 5-FU. When further examined for its anticancer mechanism, SB365 effectively suppressed the AKT/mTOR pathway both in vitro and in vivo. Taken together, our study demonstrated that SB365 inhibits the AKT/mTOR pathway, leading to the suppression of tumor growth and angiogenesis together with induction of apoptosis. Therefore, SB365 is a good candidate as a natural product for use in the treatment of colon cancer.

Anti-cancer effects of a novel compound HS-113 on cell growth, apoptosis, and angiogenesis in human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the most common malignancies, yet there have been no significant advances in effective therapeutics. In this study, HS-113 was synthesized as a novel compound, N-(5-(2-bromobenzyl) thiazole-2-yl) benzofuran-2-carboxamide and its cytotoxic activity and anti-cancer effect were examined in human HCC cells. HS-113 strongly suppressed growth of HCC cells in a dose-dependent manner, induced apoptosis by increasing the proportion of sub-G1 apoptotic cells, and caused cell cycle arrest at G0/G1 phase. Also, HS-113 increased the expression of p27 and decreased that of cyclin D1 associated with cell cycle arrest. Apoptosis by HS-113 was confirmed by DAPI and TUNEL staining, and the increases of the cleaved PARP and caspase-3 were observed. Furthermore, HS-113 decreased protein expression of HIF-1α and secretion of VEGF, and inhibited the tube formation of HUVECs. These results showed that HS-113 not only inhibited cell growth and angiogenesis, but also induced apoptosis of human HCC cells. We suggest that HS-113 may be a potential candidate for cancer therapy against HCC.

KRC-408, a novel c-Met inhibitor, suppresses cell proliferation and angiogenesis of gastric cancer

Among many cancer therapeutic targets, c-Met receptor tyrosine kinase has recently given particular attention. This kinase and its ligand, hepatocyte growth factor (HGF), play a central role in cell proliferation and the survival of several human cancers. Thus, we developed KRC-408 as a novel c-Met inhibitor and investigated its anti-cancer effects on human gastric cancer. KRC-408 inhibited the phosphorylation of c-Met and its constitutive downstream effectors such as phosphatidylinositol 3-kinase (PI3K), Akt, Mek, and Erk. This compound was found to exert anti-cancer effects stronger than those of 5-fluorouracil (5-FU) on gastric cancer cells, especially cell lines that overexpressed c-Met. Interestingly, cytotoxicity of KRC-408 was lower than that of 5-FU in normal gastric cells. Apoptosis induced by KRC-408 was accompanied by increased levels of cleaved caspase-3 and PARP as well as DNA condensation and fragmentation. Flow cytometry analysis showed an accumulation of gastric cancer cells in the G2/M phase with concomitant loss of cells in the S phase following treatment with this drug. In the angiogenesis studies, KRC-408 inhibited tube formation and migration of human umbilical vein endothelial cells (HUVECs), and suppressed microvessel sprouting from rat aortic rings ex vivo along with blood vessel formation in a Matrigel plug assay in mice. Results of an in vivo mouse xenograft experiment showed that the administration of KRC-408 significantly delayed tumor growth in a dose-dependent manner, and suppressed Akt and Erk phosphorylation as well CD34 expression in tumor tissues. These findings indicate that KCR-408 may exert anti-tumor effects by directly affecting tumor cell growth or survival via the c-Met receptor tyrosine kinase pathway. We therefore suggest that KRC-408 is a novel therapeutic candidate effective against gastric cancers that overexpress c-Met.