Inhibitory Effects of (-)-Epigallocatechin-3-gallate on Esophageal Cancer.

There is epidemiological evidence showing that drinking green tea can lower the risk of esophageal cancer (EC). The effect is mainly attributed to tea polyphenols and their most abundant component, (-)-epigallocatechin-3-gallate (EGCG). The possible mechanisms of tumorigenesis inhibition of EGCG include its suppressive effects on cancer cell proliferation, angiogenesis, DNA methylation, metastasis and oxidant stress. EGCG modulates multiple signal transduction and metabolic signaling pathways involving in EC. A synergistic effect was also observed when EGCG was used in combination with other treatment methods.

NPFF2 receptor is involved in the modulatory effects of neuropeptide FF for macrophage cell line.

Neuropeptide FF (NPFF) interacts with specific receptors to regulate diverse biological processes. Its modulatory effect in the immune field, however, has not been fully explored yet. Here, we report that NPFF2 receptors may be functionally expressed in two immune cell models, the primary peritoneal macrophage and RAW 264.7 macrophage. Firstly, the mRNA levels of NPFF2 receptor were up-regulated in macrophages when treated with LPS for 24 to 72 h. Subsequently, our data hinted that NPFF regulates the viability of both kinds of macrophages. After treatment with RF9, a reported antagonist for both NPFF receptors, delayed or inhibited the NPFF-induced macrophages viability augmentation, suggesting the involvement of NPFF2 receptor. Furthermore, down-regulation of nitric oxide (NO) synthases (NOSs) partially significantly inhibited the viability augmentation of macrophages induced by NPFF, implying a nitric oxide synthases- dependent pathway is involved. However, the NOSs are not the only route by which NPFF affects the viability of macrophages. Pharmacological inhibitors of NF-κB signal pathway also blocked the NPFF-induced macrophages growth, suggesting the involvement of the NF-κB signal pathway. The regulation activity of NPFF for macrophages suggests that NPFF could act as a potential hormone in the control of immune system. Collectively, our data provide new evidence about the immune modulatory effect of NPFF, which will be helpful in extending the scope of NPFF functions.

Neuropeptide FF activates ERK and NF kappa B signal pathways in differentiated SH-SY5Y cells.

Neuropeptide FF (NPFF) has been reported to play important roles in regulating diverse biological processes. However, little attention has been focused on the downstream signal transduction pathway of NPFF. Here, we used the differentiated neuroblastoma cell line, dSH-SY5Y, which endogenously expresses hNPFF2 receptor, to investigate the signal transduction downstream of NPFF. In particular we investigated the regulation of the extracellular signal-regulated protein kinase (ERK) and the nuclear factor kappa B (NF-κB) pathways by NPFF in these cells. NPFF rapidly and transiently stimulated ERK. H89, a selective inhibitor of cyclic AMP-dependent protein kinase A (PKA), inhibited the NPFF-activated ERK pathway, indicating the involvement of PKA in the NPFF-induced ERK activation. Down-regulation of nitric oxide synthases also attenuated NPFF-induced ERK activation, suggesting that a nitric oxide synthase-dependent pathway is involved. Moreover, the core upstream components of the NF-κB pathway were also significantly activated in response to NPFF, suggesting that the NF-κB pathway is involved in the signal transduction pathway of NPFF. Collectively, these data demonstrate that nitric oxide synthases are involved in the signal transduction pathway of NPFF, and provide the first evidence for the interaction between NPFF and the NF-κB pathway. These advances in our interpretation of the NPFF pathway mechanism will aid the comprehensive understanding of its function and provide novel molecular insight for further study of the NPFF system.

Membrane active antitumor activity of NK-18, a mammalian NK-lysin-derived cationic antimicrobial peptide.

As the increasing emergence of multi-drug resistant tumor cells, there is an urgent need for developing new chemotherapeutic agents. NK-lysin was a novel effector of cytotoxic T cells and natural killer (NK) cells and had broad antimicrobial activity. In this study, we developed a core region of NK-lysin termed NK-18, and studied its antitumor activity and possible action mode. Our results showed that NK-18 (with 18 amino acids) possesses potent antitumor activity against bladder and prostate cancer cells by disrupting the integrity of cell membrane, but has negligible hemolysis activity against mouse erythrocytes. In addition, CD spectra was employed to study its conformation in membrane mimicking environment. NK-18 takes a standard α-helical conformation in membrane mimicking environment, which could be accounted for its more potent antitumor activity compared with its low α-helical content homologous derivatives. These findings together with its shorter amino acid sequence and lower synthesis cost suggest that NK-18 could present an alternative therapeutic strategy to cancer chemotherapy and play a promising role in fighting the multi-drug resistant tumors.

A novel analog of antimicrobial peptide Polybia-MPI, with thioamide bond substitution, exhibits increased therapeutic efficacy against cancer and diminished toxicity in mice.

Polybia-MPI (MPI), a short cationic α-helical antimicrobial peptide, exhibited excellent anticancer activity and selectivity in vitro in our previous studies. To improve its in vivo application, we synthesized an analog (MPI-1) of MPI by replacing the C terminal amide -[CO-NH(2)] with thioamide -ψ[CS-NH(2)]. Although there is just one atom difference, the MPI-1 exhibited some surprising properties. In vitro studies revealed that MPI-1 exhibited relatively high lytic activity over MPI, whereas its stability to enzymatic degradation in serum was improved remarkably. Despite the enhanced toxicity in vitro, MPI-1 exhibited significantly lower mortality to mice than MPI at 75 mg/kg. Importantly, in vivo anticancer activity study indicated that MPI-1 could remarkably suppress the growth of sarcoma xenograft tumors more efficiently than MPI. Therefore, the significantly improved anticancer activity and predominantly lower in vivo toxicity might allow MPI-1 to be a good candidate for future anticancer treatment.

In vitro and in vivo antitumor effects of novel actinomycin D analogs with amino acid substituted in the cyclic depsipeptides.

The actinomycin D (AMD) analogs in which the D-valine residues (the second amino acid residue in the cyclic depsipeptide of AMD) and the N-methyl-L-valine residues (the fifth amino acid residue in the cyclic depsipeptide of AMD) were replaced with D-Phe or l- and D-forms N-methylvalines, N-methylisoleucine, N-methylleucine, N-methylphenylalanine, N-methylalanine, and sarcosine were synthesized. The antimicrobial activity and cytotoxic activities of these compounds in vitro were investigated. The results showed that most D-valine substituted analogs had much lower antimicrobial activity and cytotoxic activities in vitro than AMD itself, but three N-methyl-L-valine substituted analogs had comparable or even more remarkable cytotoxic activities in vitro than AMD. Acute toxicities and antitumor effects of the N-methyl-L-valine substituted analogs in mice were also examined. The result showed that the acute toxicity of compound 4 L-methylleucine(5)-AMD analog is comparable to AMD itself and that of compound 3(L-Methylisoleucine(5)-AMD analog) is slightly more toxic, about 1.25-fold than AMD. However, the acute toxicity of compound 5 D-methylleucine5-AMD analog is about 2-fold lower than AMD. This suggested that the N-methyl-D-amino acid replacement in the cyclic ring might play a vital role in their decreased acute toxicities, and perhaps the N-methyl-D-leucine substituent is more favorable, though there may be a slight loss of antitumor activity. This finding may be helpful for the design and development of more potent antitumor agents together with low acute toxicity, and suggests that the N-methyl-D-leucine substituent has the potential to be used as antitumor drug lead.

[Physiological responses of different peanut (Arachis hypogaea L.) varieties to cadmium stress].

To have a deep understanding on the mechanisms of cadmium (Cd) toxicity on peanut plants is of theoretical and practical significances for the selection and utilization of Cd-resistant peanut germ plasm resources. With fourteen peanut varieties as test materials and taking the chlorophyll content of functional leaves, malondialdehyde (MDA) content and cell membrane permeability of roots and leaves, and oxidative vitality of roots at flowering stage as test physiological parameters, a sand culture experiment was conducted in an artificial climate chamber to investigate the physiological responses of different peanut varieties to six levels of Cd stress. The results showed that within the range of 0-60 mg Cd x L(-1) addition, the chlorophyll content of functional leaves and the oxidative vitality of roots decreased significantly with increasing Cd addition, while the MDA content and cell membrane permeability of leaves and roots were in adverse. The cell membrane permeability of roots and leaves was the most sensitive physiological parameter, while the chlorophyll content of functional leaves was the least sensitive one in the responses of peanut plant to Cd stress. In the linear regression equations describing the relationships between test physiological parameters and Cd concentrations in nutrient solution, the absolute value of slope (b)/intercept (a) ratio, /b/a/, could better describe the sensitivity of peanut plants to Cd stress. It was known from the integrative evaluation of /b/a/ values and the cluster analysis of sensitivity that among the fourteen peanut varieties, "Zhonghua-4", "Xiangnong-55" and "Xiangnong-3010-w" were highly sensitive to Cd stress (first grade), "Lainong-29", "Xiangnongxiaoguo-w2-7", "Fenghua-2", "Lainong-13", "Yuhua-15" and "Fenghua-3" were sensitive (second grade), "Xiangnong-312", "Qiyangxiaozi" and "Pingdu-01" were less sensitive (third grade), while "Huayu-20" and "Huayu-23" were insensitive (forth grade).

Novel mode of action of polybia-MPI, a novel antimicrobial peptide, in multi-drug resistant leukemic cells.

As the frequent emergency of resistant tumor cells during treatment, the development of new agents with new modes of action attracts a great deal of interest. Polybia-MPI was a short cationic alpha-helical amphiphilic peptide that has selective toxicity toward cancer cells but no hemolytic activity. Its target selectivity is based on the binding preference to membranes containing anionic phospholipids by electrostatic driving. Its ability to make PI and trypan blue permeate into tumor cells at the same rate (within minutes), suggests a killing mechanism that involves plasma membrane perturbation. SEM and confocal microscopy experiments verified that the cell died as a result of acute injury and bursting, suggesting necrosis. As compared to the conventional chemotherapy, polybia-MPI targets at the cell membrane rather than enters into the cell to exert its action. So it is difficult for tumor cells to develop resistance to polybia-MPI during treatment and its action is not affected by the common multi-drug resistant mechanism. Although this is an initial study that looked at its in vitro activity rather than the in vivo activity, with the increasing resistance of conventional chemotherapy, polybia-MPI may offer a novel therapeutic strategy in the treatment of multi-drug resistant cancer.

Potent antitumor effects of a novel actinomycin D analog Leu5AMD.

Leu5AMD ([D-Val2, L-MeLeu5]2 AMD) is a novel actinomycin D (AMD) analog, in which both N-methylvalines were replaced by N-methylleucines. In the present study, an attempt has been made to investigate the effects of Leu5AMD on the proliferation of human gastric carcinoma cell line SGC-7901. The results showed that Leu5AMD inhibited the proliferation and induces apoptosis in SGC-7901 cells in a dose-dependent manner. Apoptosis induced by Leu5AMD was further confirmed by annexin V-FITC/PI dual staining assay. After treatment with Leu5AMD, the loss of mitochondrial potential and the decrease of bcl-2 gene expression were observed in apoptotic cells, suggesting that Leu5AMD may be involved in mitochondria and bcl-2 related apoptotic pathway. In addition, the in vivo antitumor effects of Leu5AMD on S-180 bearing mice and the acute toxicity on healthy mice were investigated. Treatment with Leu5AMD markedly suppressed the growth of Sarcoma xenograft. These results suggest that Leu5AMD may be used as a promising chemotherapeutical agent for patients affected by gastric carcinoma and other solid cancer.

Antitumor effects, cell selectivity and structure-activity relationship of a novel antimicrobial peptide polybia-MPI.

A novel antimicrobial peptide, polybia-MPI, was purified from the venom of the social wasp Polybia paulista. It has potent antimicrobial activity against both Gram-positive and Gram-negative bacteria, but causing no hemolysis to rat erythrocytes. To date, there is no report about its antitumor effects on any tumor cell lines. In this study we synthesized polybia-MPI and studied its antitumor efficacy and cell selectivity. Our results revealed that polybia-MPI exerts cytotoxic and antiproliferative efficacy by pore formation. It can selectively inhibit the proliferation of prostate and bladder cancer cells, but has lower cytotoxicity to normal murine fibroblasts. In addition, to investigate the structure-activity relationship of polybia-MPI, three analogs in which Leu7, Ala8 or Asp9 replaced by L-Pro were designed and synthesized. L-Pro substitution of Leu7 or Asp9 significantly reduces the content of alpha-helix conformation, and L-Pro substitution of Ala8 can disrupt the alpha-helix conformation thoroughly. The L-Pro substitution induces a significant reduction of antitumor activity, indicating that the alpha-helix conformation of polybia-MPI is important for its antitumor activity. In summary, polybia-MPI may offer a novel therapeutic strategy in the treatment of prostate cancer and bladder cancer, considering its relatively lower cytotoxicity to normal cells.

[Research advances in cadmium pollution of peanut (Arachis hypogaea L.)].

Peanut (Arachis hypogaea L.) is a major oil-bearing crop in the world, and as well, an important resource of plant protein and a main raw material for food processing. With the increasing of its direct human consumption and food processing, the Cd concentration in peanut kernel has aroused great concern in recent years. China is a main country of the production and exportation of peanut, but the Cd enrichment in peanut kernel is the main obstacle for its peanut export trade. In this paper, the research advances in Cd pollution of peanut kernel were reviewed, based on the characteristics and mechanisms of Cd accumulation and distribution in peanut kernel, the intra-specific variation of kernel Cd content, and the measures in controlling kernel Cd content. Two strategies were put forward for controlling Cd pollution of peanut kernel, i.e., to reduce the Cd uptake by main root system of peanut plant, and to control the transference of Cd from root to fruit (kernel). In order to applying the strategies effectively, researches on the mechanisms of Cd accumulation in peanut kernel should be enhanced in three aspects, i.e., root vitality and its relationship with Cd accumulation in kernel, mechanism of fruit Cd absorption and its contribution to kernel Cd content, and mechanism of Cd transference in plants and its effects on kernel Cd content.

[Effects of cadmium on rice seed germination].

With 319 rice varieties as test objects, this paper studied the effects of cadmium on their seed germination. The results showed that after treated with 10 mg x L(-1) of Cd2+, seed germination rate was less affected, but root growth was restrained evidently. Cadmium had more serious impact on root than on sprout. Different rice varieties had different germination responses to Cd2+, with the sequence of conventional rice (Japonica rice) > hybrid rice (Indianica rice) > conventional rice (Indianica rice). The root length and number of two-line sterilities were restrained more strongly than those of three-line sterilities. Based on their responses to Cd2+, the test 319 varieties were clustered into 3 types, i.e., endurant type, medium type, and sensitive type.