水溶性羧甲基茯苓次聚糖的合成及性能研究

羧甲基茯苓次聚糖具有明显的抗肿瘤活性,有希望作为优良的细胞药物响应的免疫促进剂。本文研究了水溶性羧甲基茯苓次聚糖的合成工艺,确定了β-茯苓次聚糖羧甲基化条件.并用IR、~(13)C NMR对化合物进行了结构表征。     

Selective isolation of bioactive soil actinomycetes belonging to the Streptomyces violaceusniger phenotypic cluster

AIMS: To devise and evaluate a strategy for isolating members of the Streptomyces violaceusniger phenotypic cluster, which are known to be a promising source of bioactive metabolites. METHODS AND RESULTS: The treatment of four soil samples with 1.5% phenol (30 degrees C, 30 min) prior to inoculation on humic acid-vitamin (HV) agar eliminated most of the streptomycetes and other bacterial populations. The surviving streptomycetes on the HV isolation plates were subcultured, and species-group identification was made according to the probabilistic identification system of Williams et al. (1989). Of the 133 streptomycetes subcultured, 102 (77%), were assigned to the S. violaceusniger cluster. A test with an overlay technique revealed that all of these S. violaceusniger-cluster isolates had broad antimicrobial spectra, as they inhibited the growth of all test Gram-positive bacteria, yeasts and filamentous fungi. Antitumour activity against colon carcinoma cells was found among 68 or 67%, of these S. violaceusniger-cluster isolates, following growth in submerged culture. CONCLUSIONS: Chemical pretreatment of soil samples with phenol reduces the growth of ubiquitous Streptomyces species, thereby facilitating the recovery of less-abundant S. violaceusniger-cluster strains that are characterized by high antimicrobial and antitumour activities. SIGNIFICANCE AND IMPACT OF THE STUDY: The development and application of new methodologies with which to selectively isolate rare, bioactive streptomycete groups is important for discovering novel secondary metabolites with bioactive properties.     

Membrane‐bound HSP70‐engineered myeloma cell‐derived exosomes stimulate more efficient CD8+ CTL‐ and NK‐mediated antitumour immunity than exosomes released from heat‐shocked tumour cells expressing cytoplasmic HSP70

Exosomes (EXO) derived from tumour cells have been used to stimulate antitumour immune responses, but only resulting in prophylatic immunity. Tumour‐derived heat shock protein 70 (HSP70) molecules are molecular chaperones with a broad repertoire of tumour antigen peptides capable of stimulating dendritic cell (DC) maturation and T‐cell immune responses. To enhance EXO‐based antitumour immunity, we generated an engineered myeloma cell line J558_HSP expressing endogenous P1A tumour antigen and transgenic form of membrane‐bound HSP70 and heat‐shocked J558_HS expressing cytoplasmic HSP70, and purified EXO_HSP and EXO_HS from J558_HSP and J558_HS tumour cell culture supernatants by ultracentrifugation. We found that EXO_HSP were able to more efficiently stimulate maturation of DCs with up‐regulation of Ia^b, CD40, CD80 and inflammatory cytokines than EXO_HS after overnight incubation of immature bone‐marrow‐derived DCs (5 × 10⁶ cells) with EXO (100 μg), respectively. We also i.v. immunized BALB/c mice with EXO (30 μg/mouse) and assessed P1A‐specific T‐cell responses after immunization. We demonstrate that EXO_HSP are able to stimulate type 1 CD4⁺ helper T (Th1) cell responses, and more efficient P1A‐specific CD8⁺ cytotoxic T lymphocyte (CTL) responses and antitumour immunity than EXO_HS. In addition, we further elucidate that EXO_HSP‐stimulated antitumour immunity is mediated by both P1A‐specific CD8⁺ CTL and non‐P1A‐specific natural killer (NK) responses. Therefore, membrane‐bound HSP70‐expressing tumour cell‐released EXO may represent a more effective EXO‐based vaccine in induction of antitumour immunity.     

白细胞介素21的生物学功能及其抗肿瘤效应

白细胞介素21（IL-21）属于I类细胞因子,主要由活化的CD4＋T产生,作用于免疫系统中的大部分骨髓、淋巴细胞,具有广泛的生物学功能,是联系主动免疫与被动免疫的中间因子。IL-21能够调节体液和细胞介导的免疫应答,促进T细胞增殖分化,调节B细胞的增殖分化与调亡,增强NK细胞的细胞毒性作用与免疫监督功能。此外,IL-21还具有抗肿瘤作用,与其他细胞因子、疫苗等联合应用,可增强其抑制肿瘤细胞生长的功能。该文综述了IL-21的生物功能及其应用于抗肿瘤治疗的研究前景。     

In vitro and in vivo antitumour effects of phenylboronic acid against mouse mammary adenocarcinoma 4T1 and squamous carcinoma SCCVII cells

The cytotoxic activity of phenylboroxine acid was evaluated in vitro on mouse mammary adenocarcinoma 4T1, mouse squamous cell carcinoma SCCVII, hamster lung fibroblast V79 and mouse dermal fibroblasts L929 cell lines. The cytotoxic effects were dose dependent for all tested tumour and non-tumour cell lines. Under in vivo conditions, three application routes of phenylboronic acid were studied: intra-peritoneal (i.p.), intra-tumour (i.t.) and per-oral. After tumour transplantation in syngeneic mice, phenylboronic acid was shown to slow the growth of both tumour cell lines (4T1 and SCCVII) compared with the control. The inhibitory effects were pronounced during the application of phenylboronic acid. For both tested tumour cell lines, the most prominent antitumour effect was obtained by intraperitoneal administration, followed significantly by oral administration.     

Influence of some chromophore substituents on the intercalation of anthracycline antibiotics into DNA

The interaction between some chromopore-modified daunorubicin derivatives and calf thymus DNA was studied using a number of physical techniques in order to investigate the effect substituents on the aromatic ring system have on the capacity to intercalate into DNA and on the DNA binding affinity. The modifications examined include methylation of the hydroxyl groups at the 6 and 11 positions of the B ring and removal of the 11-hydroxyl group. The studies showed that only 11-deoxydaunorubicin retains the ability to bind to DNA by the intercalation mechanism typical of the parent compound, although the structural modification leads to an appreciably weaker binding. In contrast, methylation of any hydroxyl group dramatically reduces the affinity of the drug for DNA. At physiological ionic strength both methyl ether derivatives showed no evidence of intercalation. Structure activity correlations for the intercalation reaction deduced from these studies are in agreement with earlier findings and hypotheses relating to antitumour activity.     

Potent antitumour of the mTORC1/2 dual inhibitor AZD2014 in docetaxel-sensitive and docetaxel-resistant castration-resistant prostate cancer cells

Recent studies indicate mammalian target of rapamycin (mTOR) may play an important role in PCa progression and drug resistance. Here, we investigated the effects of a novel mTORC1/C2 dual inhibitor, AZD2014, on naive and docetaxel (Doc)-pre-treated castration-resistant PCa (CRPC) cells and explored its therapeutic potential in CRPCs. In the current study, AZD2014 has a greater inhibitory effect against 4EBP1 and AKT phosphorylation than rapamycin in CRPC cells and prevented the feedback activation of AKT signalling. Importantly, AZD2014 suppressed CRPC cell growth in vitro by suppressing proliferation, apoptosis, cell cycle arrest at G1 phase and autophagy to a greater extent than rapamycin. Moreover, AZD2014 was more efficacious than rapamycin in inhibiting migration, invasion and EMT progression in Doc-sensitive and Doc-resistant CRPC cells. Overall, AZD2014 showed significant antitumour effects. Thereby, the current study highlights a reliable theoretical basis for the clinical application of AZD2014 in both Doc-sensitive and Doc-resistant CRPCs.