Antiagiogenesis represents a promising approach to cancer therapy. We have previously demonstrated that the antitumor effects of endostatin, one of the most potent angiostatic agents, could be enhanced when combined with immunotherapy. Our current study evaluated whether anti-tumor immune response could also potentiate the therapuetic efficacy of another antiangiogenic drug, angiostatin. METHODS AND RESULTS: Using Matrigel assay, we showed that our preparation of recombinant angiostatin possessed potent anti-angiogenic activity in vivo. The antitumor effects of recombinant angiostatin were tested against weakly-immunogenic 3LL Lewis lung carcinoma versus its highly immunogenic variant 3LL-C75. We showed that angiostatin inhibited the growth of 3LL-C75 more potently than that of 3LL tumor, suggesting that the host's immune response potentiates the antitumor effects of angiostatin. This conclusion was further supported by the finding that the antitumor activity of angiostatin against 3LL-C75 tumor was lower in immunodeficient nude mice in comparison with immunocompetent mice. Immunization of C57BL/6 mice with 3LL-C75 cells stimulated the antitumor immunity and inhibited the growth of parental 3LL tumor. Angiostatin treatment of immunized mice further enhanced the antitumor effect of tumor vaccination. CONCLUSION: Antitumor immune response could complement the therapeutic efficacy of angiostatin.

Protocatechualdehyde (PA, a dihydroxybenzene derivative) has previously been shown to induce apoptotic cell death in cytotoxic T cells (CTLL-2). However, the molecular mechanisms by which PA regulates apoptosis are still unclear. In this study, the possible roles of ornithine decarboxylase activity (ODC) and mitogen-activated protein kinases (MAPKs) in the PA-induced apoptosis process were further investigated. We demonstrated that PA inhibited ODC activity induced by IL2 in a time- and dose-dependent manner. Furthermore, the expression of ODC mRNA stimulated by IL2 was also effectively suppressed. 0.12mM PA inhibited the activation of ERK1/2 induced by IL2 and enhanced the activation of JNK, which was abrogated by IL2. No alteration in the effect of p38 MAPK on the apoptosis process was observed in the CTLL-2 cells. PD98059 (a specific ERK1/2 inhibitor) inhibited cell growth, led to cell apoptotic death and effectively decreased ODC activity and suppressed ERK1/2 activation induced by IL2. These data indicate that PA induced apoptosis in CTLL-2 cells by two mechanisms; either via inhibiting ODC induction or interfering with MAPK signaling pathways.

OBJECTIVE: To purify Methamidophos (Met) monoclonal antibodies with two methods and compare immune activity of purified antibodies. METHOD: Caprylic acid ammonium sulphate precipition (CAASP) method and Sepharose protein-A (SPA) affinity chromatography method were used to purify Met monoclonal antibodies, UV spectrum scanning was used to determine protein content and recovery of purified antibodies, sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze the purity of purified antibodies, and enzyme-linked immunosorbent assay (ELISA) was used to determine immune activity of purified antibodies. RESULTS: Antibody protein content and recovery rate with CAASP method were 7.62mg/mL and 8.05% respectively, antibody protein content and recovery rate with SPA method were 6.45mg/mL and 5.52% respectively. Purity of antibodies purified by SPA method was higher than that by CAASP method. The half-maximal inhibition concentration (IC50) of antibodies purified by SPA to Met was 181.26 microg/mL, and the linear working range and the limit of quantification (LOD) were 2.43-3896.01 microg/mL and 1.03 microg/mL, respectively. The IC50 of antibodies purified by CAASP to Met was 352.82 microg/mL, and the linear working range and LOD were 10.91-11412.29 microg/mL and 3.42 microg/mL, respectively. CONCLUSION: Antibodies purified by SPA method are better than those by CAASP method, and Met monoclonal antibodies purified by SPA method can be used to prepare gold-labelled testing paper for analyzing Met residue in vegetable and drink water.

AIM: To evaluate the effects of 3,3'-diethyl-9-methylthia-carbocyanine iodide (DMTCCI) on DNA primase activity and on apoptosis of human hepatocellular carcinoma BEL-7402 cells. METHODS: DNA primase assay was used to investigate DNA primase activity. MTT assay was applied to determine cell proliferation. Flow cytometric analysis, transmission electron microscopy, DNA fragmentation assay were performed to detect DMTCCI-induced apoptosis. Expression levels of p53, Bcl-2, Bcl-xL, Bad, Bax, survivin, Caspase-3 and poly (ADP-ribose) polymerase (PARP) were evaluated by immunoblot analysis. Caspase-3 activity was assessed with ApoAlert Caspase-3 colorimetric assay kit. RESULTS: DMTCCI had inhibitory effects on eukaryotic DNA primase activity with IC50 value of 162.2 nmol/L. It also inhibited proliferation of human hepatocellular carcinoma BEL-7402 cells with IC50 value of 2.09 μmol/L. Furthermore, DMTCCI-induced BEL-7402 cell apoptosis was confirmed by DNA fragmentation (DNA ladders and sub-G1 formation) and transmission electron microscopy (apoptotic bodies formation). During the induction of apoptosis, expression of Bcl-2, Bcl-xL and survivin was decreased, and that of p53, Bad and Bax was increased. Caspase-3 was activated and poly (ADP-ribose) polymerase (PARP) was cleaved in BEL-7402 cells treated with DMTCCI. CONCLUSION: The present data suggest that DMTCCI has inhibitory effects on eukaryotic DNA primase and can induce apoptosis of BEL-7402 cells. The modulation of expression of p53 and Bcl-2 family proteins, and activation of Caspase-3 might be involved in the induction of apoptosis.

Previous studies have demonstrated that c-Jun NH2-terminal protein kinase (JNK) plays a crucial role in neuronal apoptosis. Here, we report that indirubin-3'-oxime, a known effective inhibitor of cyclin-dependent kinases (CDKs) and glycogen synthase kinase 3-beta (GSK-3β), has a significant inhibitory effect on JNK. Kinase assay showed that indirubin-3'-oxime directly inhibited the activity of all three isoforms of JNK (JNK1, and JNK3) in vitro, with half inhibition dose (IC50) of 0.8μM, 1.4μM, and 1.0μM, respectively. In cerebellar granule neurons (CGNs), indirubin-3'-oxime blocked c-Jun phosphorylation induced by potassium withdrawal and prevented CGNs from apoptosis in a dose dependent manner. However, inhibitors of CDKs and GSK-3β were ineffective in reducing c-Jun phosphorylation both in vitro and in vivo, suggesting that indirubin-3'-oxime prevents c-Jun phosphorylation independent of its inhibition on CDKs and GSK-3β. Our studies give further supports for JNK-targeting strategy in preventing neuronal apoptosis.