Jinyu Zhang

Anticancer Properties and Mechanisms of Fucoidan on Mouse Breast Cancer In Vitro and In Vivo

Background Fucoidan is a sulfated polysaccharide derived from brown algae that has been reported to perform multiple biological activities, including antitumor activity. In this study, we examined the influence of crude fucoidan on mouse breast cancer in vitro and in vivo. Materials and Methods In vitro, fluorescent staining, flow cytometry and Western blot were performed to analyze apoptosis and vascular endothelial growth factor (VEGF) expression of mouse breast cancer 4T1 cells. In vivo, therapy experiments were conducted on Babl/c mice bearing breast cancer. The tumor volume and weight were measured. The number of apoptotic cells and microvascular density (MVD) in tumor tissues were assessed by TUNEL and CD34 immunostaining. Immunohistochemical assays and ELISA assay were used to detect the expression of VEGF in tissues. Results In vitro studies showed that crude fucoidan significantly decreased the viable number of 4T1 cells, induced apoptosis and down-regulated the expression of VEGF. The expression of Bcl-2 was decreased, and the ratio of Bcl-2 to Bax was significantly decreased. The expression of Survivin and phosphorylated extracellular signal regulated protein kinases (ERKs) was decreased. Cytochrome C was released from mitochondria into cytosol, and the cleaved Caspase-3 protein rose after fucoidan treatment. Intraperitoneal injection of fucoidan in breast cancer models reduced the tumor volume and weight. The enhanced antitumor efficacy was associated with decreased angiogenesis and increased induction of apoptosis. Conclusion These findings indicated that crude fucoidan inhibited mouse breast cancer growth in vitro and in vivo. These data suggest that fucoidan may serve as a potential therapeutic agent for breast cancer.

Fucoidan inhibited 4T1 mouse breast cancer cell growth in vivo and in vitro via downregulation of Wnt/β-catenin signaling.

Fucoidan is a sulfated polysaccharide derived from brown algae and is known to possess anticancer properties. However, the relationship between fucoidan and β-catenin, one of the key components of the Wnt signaling pathway, in mouse breast cancer remains poorly characterized. In this study, mouse breast cancer cells (4T1) were exposed to fucoidan to investigate the relationship between fucoidan and the Wnt/β-catenin signaling pathway in vivo and in vitro. We found that fucoidan significantly inhibited cell growth, increased cell death, and induced G1 cell cycle arrest in 4T1 cells. Fucoidan also reduced β-catenin expression and T cell factor/lymphoid-enhancing factor reporter activity. Furthermore, fucoidan downregulated the expression of downstream target genes such as c-myc, cyclin D1, and survivin. Intraperitoneal injection of fucoidan in tumor-bearing mice reduced the tumor volume and weight. Fucoidan induced aberrant downregulation of β-catenin in tumor tissues with a significant increase in apoptosis. Thus, our data suggested that fucoidan exerts its anticancer activity through downregulation of Wnt/β-catenin signaling. Fucoidan may be an effective therapy for the chemoprevention and treatment of mouse breast cancer.

Antitumor effects of Isatin on human neuroblastoma cell line (SH-SY5Y) and the related mechanism

The purpose of the study was to investigate the antitumor effects of Isatin and the related mechanism. Human neuroblastoma cells (SH-SY5Y) were exposed to Isatin at different concentrations for 48 h. Apoptotic features were demonstrated by means of nuclei staining with Hoechst 33258 and flow cytometry with propidium iodide (PI). Expressions of Bcl-2, Bax and vascular endothelial growth factor (VEGF) mRNA were analyzed via RT-PCR. Expressions of Bcl-2, Bax proteins and phosphorylated extracellular signal regulated protein kinases (ERKs, p42/p44) were analyzed via Western blot. Activation of caspase-3 was assayed by flow cytometry with anti-active caspase-3-McAb-PE. VEGF protein was determined by ELISA kits. And the results showed that apoptosis of SH-SY5Y cells were induced by Isatin in a dose-dependent manner. Expressions of Bcl-2, VEGF mRNA and Bcl-2, VEGF proteins were down-regulated, while expressions of Bax mRNA and Bax protein were not changed obviously. Expression of phosphorylated ERKs decreased, but the level of activated caspase-3 increased after treatment of Isatin. These results suggest that Isatin promotes the apoptosis of neuroblastoma cells, therefore, it might be a potential candidate for the treatment of neuroblastoma.

Phytic acid attenuates inflammatory responses and the levels of NF-κB and p-ERK in MPTP-induced Parkinson's disease model of mice.

Phytic acid (PA) is a naturally occurring constituent which exhibits protective action in Parkinsons disease (PD). Inflammation in the central nervous system (CNS) is strongly associated with neuronal death in PD. However, the molecular mechanism of the protective effect of PA in PD has not been fully elucidated. In this study, we tried to testify the protection of PA on neuron and inflammatory responses in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model of mice and investigated the mechanism involved in them. Motor behavior test and tyrosine hydroxylase (TH) immunohistochemistry method showed PA significantly inhibited MPTP-induced dopaminergic cell loss in the substantia nigra (SN). Moreover, using immunohistochemistry method and quantitative polymerase chain reaction (qPCR), microglial activation and inducible nitric oxide synthase (iNOS) were found to be markedly repressed by PA. Via western blot assay, expressions of nuclear factor κB (NF-κB) and phosphorylated extracellular signal-regulated kinase (p-ERK) were significantly attenuated by PA. In conclusion, it is suggested that PA has a neuroprotective effect in MPTP-induced PD model and the neuroprotection is correlated with its anti-inflammatory effect which may be associated with suppression of pathways that involved in NF-κB and p-ERK.

The mechanisms on apoptosis by inhibiting VEGF expression in human breast cancer cells

This study investigated apoptotic mechanisms of down-expression vascular endothelial growth factor (VEGF) by short interfering RNA (siRNA) in human breast cancer MCF-7 cells. Human breast cancer cells were evaluated for the expression of VEGF and VEGF receptor 2 (VEGFR-2). siRNA targeting VEGF mRNA were chemically synthesized and transfected into cells with Lipofectamine2000. In vitro assessments were then made of the ability of anti-VEGF siRNA to knock down expression of VEGF and the subsequent effect this decreased expression had on breast cancer cell apoptosis. Growth curve construction and nude mice experimentation in vivo were performed to assess the effects of VEGF silencing on tumor growth. Those cells transfected with siRNA targeting VEGF showed a 65% knockdown in VEGF expression and a marked increase in cell apoptosis. The expression of Bcl-2 protein in MCF-7 cells was decreased, the level of Bax protein was kept the same, cytochrome c was released from mitochondria into cytosol, and the cleaved Caspase-3 protein rose after siRNA transfection. The siRNA targeting human VEGF could induce apoptosis in MCF-7 cells and the mechanism of apoptosis is possibly related with changing Bcl-2/Bax expression ratio, releasing cytochrome c from mitochondria into cytosol, and up-regulation of Caspase-3 protein, but also could suppress the growth of breast cancer cells in vivo. VEGF might be a potential therapeutic target for human breast cancer.

PUFA diets alter the microRNA expression profiles in an inflammation rat model

Omega-3 and -6 polyunsaturated fatty acids (PUFAs) can directly or indirectly regulate immune homeostasis via inflammatory pathways, and components of these pathways are crucial targets of microRNAs (miRNAs). However, no study has examined the changes in the miRNA transcriptome during PUFA-regulated inflammatory processes. Here, we established PUFA diet-induced autoimmune-prone (AP) and autoimmune-averse (AA) rat models, and studied their physical characteristics and immune status. Additionally, miRNA expression patterns in the rat models were compared using microarray assays and bioinformatic methods. A total of 54 miRNAs were differentially expressed in common between the AP and the AA rats, and the changes in rno-miR-19b-3p, -146b-5p and -183-5p expression were validated using stem-loop reverse transcription-quantitative polymerase chain reaction. To better understand the mechanisms underlying PUFA-regulated miRNA changes during inflammation, computational algorithms and biological databases were used to identify the target genes of the three validated miRNAs. Furthermore, Gene Ontology (GO) term annotation and KEGG pathway analyses of the miRNA targets further allowed to explore the potential implication of the miRNAs in inflammatory pathways. The predicted PUFA-regulated inflammatory pathways included the Toll-like receptor (TLR), T cell receptor (TCR), NOD-like receptor (NLR), RIG-I-like receptor (RLR), mitogen-activated protein kinase (MAPK) and the transforming growth factor-β (TGF-β) pathway. This study is the first report, to the best of our knowledge, on in vivo comparative profiling of miRNA transcriptomes in PUFA diet-induced inflammatory rat models using a microarray approach. The results provide a useful resource for future investigation of the role of PUFA-regulated miRNAs in immune homeostasis.

Isatin inhibits proliferation and induces apoptosis of SH-SY5Y neuroblastoma cells in vitro and in vivo

The purpose of this study was to investigate the anti-tumor effects of the isatin in vitro and in vivo. Human neuroblastoma cells (SH-SY5Y) were exposed to isatin at various concentrations (0, 50, 100, 200 μmol/l) for 48 h. Bcl-2 and Bax mRNA were analyzed via RT-PCR. Bcl-2, Bax, the inhibitor of caspase-activated DNase (ICAD) and cytochrome c protein were analyzed via western blot. Apoptosis, caspase-9, 3 activation and mitochondrial depolarization were assayed by flow cytometry. SH-SY5Y cells were injected into the right side of the mouse armpit. When the neoplasm was detected, the nude mice were randomly divided into four groups and received an injection of DMEM (negative control), 25 or 50mg/kg isatin, or cyclophosphamide (positive control). The inhibitory effects of isatin on the murine xenograft were determined using a growth curve and Bcl-2 and Bax mRNA and protein were studied using RT-PCR and western blot, respectively. The results showed that apoptosis of SH-SY5Y cells was induced by isatin. Furthermore, Bcl-2 expression was decreased and the ratio of Bcl-2 to Bax was significantly decreased by isatin. The mitochondrial transmembrane potential was markedly reduced and the release of cytochrome c into the cytosol was increased after treatment with isatin. Simultaneously, caspase-9, 3 was activated, followed by degradation of ICAD, a caspase-3 substrate. Finally, tumor xenograft growth was markedly suppressed and a decrease was found in Bcl-2 and Bax expression in vivo. These results suggest that isatin can induce apoptosis and inhibit the growth of neuroblastoma cells via the mitochondrial pathway.

Chemically modified siRNA directed against the KDR gene inhibits the proliferation of breast cancer cells.

Vascular endothelial growth factor receptor-2 or kinase insert domain-containing receptor (VEGFR2/KDR) is secreted by most solid tumors, including breast cancer, and is an important mediator of angiogenesis. To observe the effects of KDR gene expression on cell proliferation and the cell cycle in MCF-7 cells in vitro and in vivo, we used chemically modified siRNA directed against KDR. The results revealed that chemically modified siRNA transfection of the KDR gene effectively inhibited the proliferation of MCF-7 cells, arrested cells in the G1 phase and down-regulated the expression of KDR. In addition, in the progression of cell cycle arrest induced by siRNA, phosphorylated ERK and CDK1 expression was down-regulated (P<0.01). In vivo, the growth of tumors was visibly suppressed. RT-PCR and the results of immunohistochemistry indicated that KDR mRNA and protein expression was reduced in the excised tumors. In contrast, there were no obvious changes in the control groups. This implies that chemically modified KDR siRNA markedly decreases KDR gene expression and inhibits cellular proliferation in vitro, as well as suppressing tumor growth in a xenograft model. KDR may be a new target for breast cancer treatment.

Transgenic n-3 PUFAs enrichment leads to weight loss via modulating neuropeptides in hypothalamus

Body weight is related to fat mass, which is associated with obesity. Our study explored the effect of fat-1 gene on body weight in fat-1 transgenic mice. In present study, we observed that the weight/length ratio of fat-1 transgenic mice was lower than that of wild-type mice. The serum levels of triglycerides (TG), cholesterol (CT), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c) and blood glucose (BG) in fat-1 transgenic mice were all decreased. The weights of peri-bowels fat, perirenal fat and peri-testicular fat in fat-1 transgenic mice were reduced. We hypothesized that increase of n-3 PUFAs might alter the expression of hypothalamic neuropeptide genes and lead to loss of body weight in fat-1 transgenic mice. Therefore, we measured mRNA levels of appetite neuropeptides, Neuropeptide Y (NPY), Agouti-related peptides (AgRP), Proopiomelanocortin (POMC), Cocaine and amphetamine regulated transcript (CART), ghrelin and nesfatin-1 in hypothalamus by real-time PCR. Compared with wild-type mice, the mRNA levels of CART, POMC and ghrelin were higher, while the mRNA levels of NPY, AgRP and nesfatin-1 were lower in fat-1 transgenic mice. The results indicate that fat-1 gene or n-3 PUFAs participates in regulation of body weight, and the mechanism of this phenomenon involves the expression of appetite neuropeptides and lipoproteins in fat-1 transgenic mice.

Neuroprotection of inositol hexaphosphate and changes of mitochondrion mediated apoptotic pathway and α-synuclein aggregation in 6-OHDA induced parkinson's disease cell model.

Animal and cell experiments showed that inositol hexaphosphate (IP6) was protective on neurons in parkinsons disease (PD) model, but the underlying mechanism of this action was not extensively elucidated. To address this question, we established 6-hydroxydopamine (6-OHDA) induced human dopaminergic cell line SH-SY5Y as PD cell model and testified the neuroprotection of IP6. Through hoechst nuclear stain method and flow cytometric analysis, apoptosis induced by 6-OHDA was blocked by IP6 pretreatment. Significant protection against reactive oxygen species (ROS) and lipid peroxidation product malondialdehyde (MDA) was observed in 6-OHDA induced cells pretreated with IP6. To further investigate the mechanism of anti-apoptotic effect of IP6, expression of mediators in mitochondrion dependent apoptotic pathway was detected. Results indicated that loss of mitochondrial membrane potential, cytochrome c releasing, upregulation of Bcl-2-associated X protein (Bax), downregulation of B-cell CLL/lymphoma 2 (Bcl-2) and caspases activation were reversed by IP6. In addition, using flow cytometric method and western blot approach, our data showed that IP6 attenuated the rise of calcium and α-synuclein aggregation in cytosol. Collectively, IP6 exerted its neuroprotection on dopaminergic cells in PD cell model and the mechanism may be associated with changes of mitochondrion mediated apoptotic pathway and α-synuclein aggregation.