Anti-tumor effect of Huaier extract against neuroblastoma cells in vitro.

Huaier extract, the main active constituent proteoglycan, has anti-tumor activity in various experimental and clinical settings. However, the potential anti-neuroblastoma and associated mechanisms have not been investigated. Therefore, in this study, we aimed to elucidate the potential role of Huaier extract in 3 human neuroblastoma cell lines. Our study demonstrated that incubation with Huaier extract resulted in a marked decrease in cell viability in a dose-dependent manner. Huaier extract induced cell cycle arrest at G0/G1 phase in neuroblastoma and decreased the cell cycle related protein expression of cyclin D3. Western blotting analysis also showed that Huaier extract induced neuroblastoma cell apoptosis and autophagy. Signaling analysis indicated that Huaier extract suppressed the MEK/ERK and mTOR signaling pathways simultaneously. In conclusion, we verify that Huaier extract causes cell proliferation inhibition, apoptosis, autophagy, and cell cycle arrest in G0/G1 phase via MEK/ERK and mTOR signaling. Huaier extract may act as a complementary agent for treating neuroblastoma.

Huaier Extract Induces Apoptosis in Hepatoblastoma Cells Via the MEK/ERK Signaling Pathway.

BACKGROUND/AIM: Huaier extract, whose main active constituent is the proteoglycan, has anti-tumor activity in several types of malignancies. In this study, we aimed to elucidate the effect of Huaier extract in hepatoblastoma cells. MATERIALS AND METHODS: The effect of Huaier extract on the proliferation of human hepatoblastoma cell lines HepG2 and HuH-6, was examined. RESULTS: Incubation with Huaier extract resulted in a marked, dose-dependent decrease in hepatoblastoma cell viability. Huaier extract induced S phase arrest in hepatoblastoma cells and upregulated the expression of the cell cycle related proteins cyclin D1 and cyclin D3. It also induced apoptosis in hepatoblastoma cells. Additionally, it significantly suppressed the activity of p-ERK and p-MEK. CONCLUSION: Huaier extract inhibits proliferation, and induces cell apoptosis and cell cycle arrest via the MEK-ERK pathway in hepatoblastoma cells. Huaier extract may act as a complementary agent for treating hepatoblastoma.

Crystal structure of mature myroilysin and implication for its activation mechanism.

Myroilysin is a novel bacterial member of M12A metalloproteases family with an uncommon "cysteine switch" activation mechanism and a unique "cap" structure. However, activation of pro-myroilysin is elusive. Here, mature myroilysin was obtained for structure determination by treating pro-myroilysin with trypsin. The structure of mature myroilysin showed that the active-site zinc ion of the mature protein is coordinated by three histidine residues, a water molecule, and a tyrosine residue (Tyr208) in the conserved Met-turn motif (SIMHY). The "cap" structure moves away from the active-site to leave the active cleft open; the newly formed N-terminus is deeply buried in myroilysin, and Glu151 forms a salt bridge directly with the first amino acid residue (Gly38), whereas they are far from each other in the pro-myroilysin. The mutation of Tyr208 indicates that Tyr208 plays an important role in activity of myroilysin. The proteolytic activity and thermostability of mutant E151A decreased dramatically, implying that Glu151 is not only important for catalysis, but also crucial for structural stability in myroilysin. Structural comparison also reveals differences existed between myroilysin and astacin. Our biochemical and structural data provide new insights into the activation of myroilysin and functional involvement of crucial residues Tyr208 and Glu151.

Induction of MEK/ERK activity by AZD8055 confers acquired resistance in neuroblastoma.

Mammalian target of rapamycin (mTOR) complex (mTORC) is frequently activated in diverse cancers. Although dual mTORC1/2 inhibitors are currently under development to treat various malignancies, the emergence of drug resistance has proven to be a major complication. AZD8055 is a novel, potent ATP-competitive and specific inhibitor of mTOR kinase activity, which blocks both mTORC1 and mTORC2 activation. In this study, we acquired AZD8055-resistant neuroblastoma (NB) cell sublines by using prolonged stepwise escalation of AZD8055 exposure (4-12 weeks). Here we demonstrate that the AZD8055-resistant sublines (TGW-R and SMS-KAN-R) exhibited marked resistance to AZD8055 compared to the parent cells (TGW and SMS-KAN). The cell cycle G1/S transition was advanced in resistant cells. In addition, the resistance against AZD8055 correlated with over-activation of MEK/ERK signaling pathway. Furthermore, combination of AZD8055 and MEK inhibitor U0126 enhanced the growth inhibition of resistant cells significantly in vitro and in vivo. In conclusion, these data show that targeting mTOR kinase and MEK/ERK signaling simultaneously might help to overcome AZD8055 resistance in NB.

Anti-tumor effect of AZD8055 against neuroblastoma cells in vitro and in vivo.

Neuroblastoma (NB) is one of the most common solid tumors in children. High-risk NB remains lethal in about 50% of patients despite comprehensive and intensive treatments. Activation of PI3K/Akt/mTOR signaling pathway correlates with oncogenesis, poor prognosis and chemotherapy resistance in NB. Due to its central role in growth and metabolism, mTOR seems to be an important factor in NB, making it a possible target for NB. In this study, we investigated the effect of AZD8055, a potent dual mTORC1-mTORC2 inhibitor, in NB cell lines. Our data showed that mTOR signaling was extensively activated in NB cells. The activity of mTOR and downstream molecules were down-regulated in AZD8055-treated NB cells. Significantly, AZD8055 effectively inhibited cell growth and induced cell cycle arrest, autophagy and apoptosis in NB cells. Moreover, AZD8055 significantly reduced tumor growth in mice xenograft model without apparent toxicity. Taken together, our results highlight the potential of mTOR as a promising target for NB treatment. Therefore, AZD8055 may be further investigated for treatment in clinical trials for high risk NB.

CD3+ B-1a Cells as a Mediator of Disease Progression in Autoimmune-Prone Mice.

B-1a cells are distinguishable from conventional B cells, which are designated B-2 cells, on the basis of their developmental origin, surface marker expression, and functions. In addition to the unique expression of the CD5 antigen, B-1a cells are characterized by the expression level of CD23. Although B-1a cells are considered to be independent of T cells and produce natural autoantibodies that induce the clinical manifestations of autoimmune diseases, there is much debate on the role of B-1a cells in the development of autoimmune diseases. We examined the involvement of B-1a cells in autoimmune-prone mice with the lpr gene. MRL/lpr and B6/lpr mice exhibited lupus and lymphoproliferative syndromes because of the massive accumulation of CD3+CD4-CD8-B220+ T cells. Interestingly, the B220+CD23-CD5+ (B-1a) cell population in the peripheral blood and peritoneal cavity increased with age and disease progression. Ninety percent of B-1a cells were CD3 positive (CD3+ B-1a cells) and did not produce tumor necrosis factor alpha, interferon gamma, or interleukin-10. To test the possible involvement of CD3+ B-1a cells in autoimmune disease, we tried to eliminate the peripheral cells by hypotonic shock through repeated intraperitoneal injections of distilled water. The fraction of peritoneal CD3+ B-1a cells decreased, and symptoms of the autoimmune disease were much milder in the distilled water-treated MRL/lpr mice. These results suggest that CD3+ B-1a cells could be mediators of disease progression in autoimmune-prone mice.

Erratum to: PDK1-mTOR signaling pathway inhibitors reduce cell proliferation in MK2206 resistant neuroblastoma cells.

[This corrects the article DOI: 10.1186/s12935-015-0239-4.].

PDK1-mTOR signaling pathway inhibitors reduce cell proliferation in MK2206 resistant neuroblastoma cells.

PURPOSE: AKT plays a pivotal role in the signal transduction of cancer cells. MK2206, an AKT inhibitor, has been shown to be an effective anti-cancer drug to a variety of cancer cell lines. However, some cancer cells acquire resistance to MK2206 and new strategies to suppress these cell lines remain to be developed. EXPERIMENTAL DESIGN: Acquired MK-2206-resistant neuroblastoma (NB) cell sublines were induced by stepwise escalation of MK-2206 exposure (4-12 weeks). MTT assay was used to validate cell proliferation. Flow cytometry was performed for cell cycle analysis. Western blot assay was used for cell signaling study. RESULTS: MK2206 (5-10 µmol) significantly suppressed cell growth of MK2206 non-resistant NB cells (LAN-1, KP-N-SIFA, NB-19 and SK-N-DZ), but is less efficient in inhibiting that of resistant sublines, even after 2-week MK2206-free incubation. MK2206 acted in mTOR-S6K dependent and independent methods. MK-2206 resistant sublines (LAN-1-MK, KP-N-SIFA-MK, and SK-N-DZ-MK) showed lower IC50 of GSK2334470 (PDK1 inhibitor). The cell growth of all sublines was prohibited by AZD8805 (mTOR inhibitor), with IC50 of AZD8805 3-10 times lower than MK2206 non-resistant cells. The signaling profiles of these resistant sublines were characterized by elevated PDK1-mTOR-S6K activity, accompanying by low phosphorylation of AKT compared with non-resistant counterparts. GSK2334470 and AZD8055 effectively inhibited phosphorylation of PDK1 and mTOR, respectively, and induced higher G0-G1 ratio in LAN-1-MK than that in LAN-1 as well. PDK1 and mTOR inhibitors effected on phosphorylation of GSK3ß in some of resistant sublines. CONCLUSION: NB cells can acquire MK2206 resistance after exposure for 4-12 weeks. Resistant cells feature reliance on PDK1-mTOR-S6K pathway and are more sensitive to PDK1 and mTOR inhibitors than the non-resistant counterparts. Thus, suppression of PDK1-mTOR-S6K signaling pathway is an effective way to overcome the MK2206 resistance, and this may be a promising strategy for targeted therapy.

Discrepancy between the effects of morronside on apoptosis in human embryonic lung fibroblast cells and lung cancer A549 cells.

Morroniside is a water-soluble compound extracted from the fruit of Cornus officinalis and is used to protect lung activity against aging. In the present study, the manner in which morroniside regulates normal lung and cancer cells was examined. The human embryonic lung fibroblast (HELF) cell line and lung cancer A549 cell line, and their responses to morroniside treatment, were examined. Results showed that morroniside reverses the apoptotic effect of H2O2 on HELF cell growth, protecting cell proliferation and normal cell morphology and inhibiting apoptosis. However, these effects were not present in A549 cells. Western blotting showed that morroniside also markedly downregulated retinoblastoma protein in HELF cells. These results suggest that morroniside treatment exhibits different effects on apoptosis in HELF and A549 cells, making it a viable compound for decreasing the side effects of anticancer medicines in normal cells.

[Study on synergistic effect of sodium cantharidinate combined with chemotherapeutic drugs on hepatic carcinoma and its effective mechanism].

OBJECTIVE: To study the synergistic effect on hepatoma cell(SMMC-7721) and the reduction killing effect on normal liver cells(LO-2) treated with sodium cantharidinate (SCA) in combination with fluorouracil(5-FU) or cisplatin(DDP) as well as the related mechanism. METHODS: MTT assay was used to select the best ratio of SCA with 5-FU or SCA with DDP which had less toxicity on LO-2 cell line and had synergistic effect on SMMC-7721 cell line; Flow cytometry assay was used to analyze the apoptosis-induction of the different ratio of drugs on both cell lines; Hoechst-33258 fluorescent staining assay was used to observe the nuclear morphological changes of cells; Immunoblotting assay was used to analyze the Ras/Raf/ERK1/2 signaling pathway and the apoptosis related signaling pathway in both cell lines. RESULTS: MTI assay indicated that the proliferation inhibition of SCA,5-FU and DDP on SMMC-7721 cell line was in a time-and dose-dependent manner respectively. Among them, SCA had a more significant inhibition on SMMC-7721 cell line than on LO-2 after 12 h or 24 h treatment (P <0. 01). Moreover, after a treatment of 48 h,the ratio of 2. 5 µg/mL SCA and 2 µg/mL DDP showed a more significant inhibition on SMMC-7721 cell line than on LO-2 cell line,which was then be considered as the optimal concentration ratio for the following experiment. Co-treatment of SCA (2. 5 µg/mL) with DDP (2 µg/mL) induced a more significant apoptosis on SMMC-7721 cell line compared with single treatment with SCA (2. 5 µg/mL) or DDP (2 µg/mL) respectively (P < 0. 01). After a 48 h treatment of the optimal ratio of drugs, the significant morphological apoptotic characteristics were observed both under inverted microscope and by Hoechst-33258 fluorescent staining assay in both cell lines. The results of Western blot assay showed that this ratio of drugs could significantly increase the protein expression of Bax,P53 and P21 and decreased the expression of BCL-2, Casepase-3, p-Erk, p-Ras and p-c-Raf in SMMC-7721 cells. Meanwhile,the effect on the proteins mentioned above was lesser in LO-2 cells. CONCLUSION: These results indicates that 2. 5 µg/mL SCA + 2 µg/mL DDP showed a higher inhibition on the hepatic carcinoma cells and a relatively lower cytotoxicity on normal liver cells. The major anti-cancer mechanism is related with the inhibition on Erk signaling pathway and the induction of apoptosis through the mitochondrial pathway.

The protection of selenium on cadmium-induced inhibition of spermatogenesis via activating testosterone synthesis in mice.

Selenium (Se) is an essential trance element in testis. However, the potential protective effects of Se against cadmium (Cd)-induced reproductive toxicity remained to be elucidated. Male ICR mice were orally administered by gavage with Na2SeO3 (0.1, 0.2, 0.4 mg/kg BW) for 1h prior to CdCl2 (5 mg/kg BW) alone or in combination for 15, 25 or 35 days. Cd exposure caused a significant decrease in body weight, sperm concentration and motility as well as plasma testosterone level which was accompanied by decreased antioxidant enzymatic activity of SOD and GSH-Px and by increased lipid peroxidation (as malondialdehyde, MDA). Se pretreatment compensated deficits in the sperm parameters (concentration, motility and morphology) induced by Cd. Se (0.4 mg/kg BW) treatment significantly increased serum testosterone level that was reduced by Cd (on 15th, 25th and 35th day) (P<0.01). Se treatment ameliorated Cd-induced reduction in testicular steroidogenic acute regulatory (StAR) and 17ß-hydroxysteroid dehydrogenase (17ß-HSD) activities. The present study suggest that the protective potential of Se against Cd-induced reprotoxicity might be due to up-regulation StAR and testosterone synthetic enzyme activity, which could be useful for increasing testosterone synthesis for achieving optimum protection in sperm quality and spermatogenesis.

[Effect of 5-hydroxymethyl furfural on BCL-2 and NF-kappaB gene expression of apoptotic rat hippocampal neurons injured by H2O2].

OBJECTIVE: To investigate the effect of 5-hydroxymethyl furfural (5-HMF) on apoptosis and BCL-2, NF-kappaB gene expression of rat hippocampal neurons injured by hydroperoxide (H2O2). METHODS: Hippocampal neurons of newly born rat were cultured in vivo and injured by H2O2. Effect of different concentration of 5-HMF on cell viability was measured by MTT. Flow cytometer (FCM) was used to measure the apoptosis of rat hippocampal neurons pre-cultured with different concentration of 5-HMF,Western blotting was used to measure the expression of BCL-2 and NF-kappaB gene. RESULTS: It revealed that the high and medium dosage of 5-HMF could increase the activity of rat hippocampal. The high, medium and low dosage of 5-HMF also increased the expression of BCL-2 gene and decreased the expression of NF-kappaB gene. CONCLUSION: 5-HMF could restrain the apoptosis of cultured hippocampal neurons injured by H2O2. The mechanism may be related to increasing in BCL-2 level and decreasing in NF-kappaB level.

Expression analysis of rice A20/AN1-type zinc finger genes and characterization of ZFP177 that contributes to temperature stress tolerance.

The A20/AN1-type zinc finger protein family is conserved in animals and plants. Using human AWP1 protein as a query, we identified twelve A20/AN1-type zinc finger proteins in japonica rice. Most of these genes were constitutively expressed in leaves, roots, culms and spikes. Through microarray analysis, it was found that four genes (ZFP177, ZFP181, ZFP176, ZFP173), two genes (ZFP181 and ZFP176) and one gene (ZFP157) were significantly induced by cold, drought and H(2)O(2) treatments, respectively. Further expression analysis showed that ZFP177 was responsive to both cold and heat stresses, but down-regulated by salt. The subcellular localization assay indicated that ZFP177 was localized in cytoplasm in tobacco leaf and root cells. Yeast-one hybrid assay showed that ZFP177 lacked trans-activation potential in yeast cells. Overexpression of ZFP177 in tobacco conferred tolerance of transgenic plants to both low and high temperature stresses, but increased sensitivity to salt and drought stresses. Further we found expression levels of some stress-related genes were inhibited in ZFP177 transgenic plants. These results suggested that ZFP177 might play crucial but differential roles in plant responses to various abiotic stresses.

Identification of a splicing enhancer in MLH1 using COMPARE, a new assay for determination of relative RNA splicing efficiencies.

Exonic splicing enhancers (ESEs) are sequences that facilitate recognition of splice sites and prevent exon-skipping. Because ESEs are often embedded within protein-coding sequences, alterations in them can also often be interpreted as nonsense, missense or silent mutations. To correctly interpret exonic mutations and their roles in diseases, it is important to develop strategies that identify ESE mutations. Potential ESEs can be found computationally in many exons but it has proven difficult to predict whether a given mutation will have effects on splicing based on sequence alone. Here, we describe a flexible in vitro method that can be used to functionally compare the effects of multiple sequence variants on ESE activity in a single in vitro splicing reaction. We have applied this method in parallel with conventional splicing assays to test for a splicing enhancer in exon 17 of the human MLH1 gene. Point mutations associated with hereditary non-polyposis colorectal cancer (HNPCC) have previously been found to correlate with exon-skipping in both lymphocytes and tumors from patients. We show that sequences from this exon can replace an ESE from the mouse IgM gene to support RNA splicing in HeLa nuclear extracts. ESE activity was reduced by HNPCC point mutations in codon 659, indicating that their primary effect is on splicing. Surprisingly, the strongest enhancer function mapped to a different region of the exon upstream of this codon. Together, our results indicate that HNPCC point mutations in codon 659 affect an auxillary element that augments the enhancer function to ensure exon inclusion.