HSP90 mRNA在胃癌和大肠癌中表达的研究

目的为探讨胃癌和大肠癌细胞HSP90 mRNA表达的特点.方法利用核酸原位杂交技术,对79例胃肠癌组织进行检测.结果表明HSP90 mRNA在胃癌和大肠癌中的阳性率分别为55.56%(15/27)和69.23%(36/52).mRNA表达与病理类型、分化程度和有否淋巴结转移有相关性.结论 HSP90 mRNA在胃肠癌中有较高表达,检测HSP90 mRNA可以作为提示预后的重要临床指标.     

Correlation of structure to antitumor activities of five derivatives of a beta-glucan from Poria cocos sclerotium

A water-insoluble (1-->3)-beta-D-glucan isolated from fresh sclerotium of Poria cocos was, respectively, sulfated, carboxymethylated, methylated, hydroxyethylated, and hydroxypropylated, to afford five water-soluble derivatives. Their weight-average molecular masses (Mw) and intrinsic viscosities ([eta]) were determined by size-exclusion chromatography combined with laser light scattering (SEC-LLS), LLS, and viscometry in phosphate buffer solution (PBS) at 37 degrees C. The antitumor activities, against Sarcoma 180 tumor cell (S-180) and gastric carcinoma cell strain (MKN-45 and SGC-7901) of the native beta-glucan and the five derivatives, were tested in vitro and in vivo. The Mw values of the five derivatives in PBS were determined to be 3.8 x 10(4), 18.9 x 10(4), 16.0 x 10(4), 76.8 x 10(4), and 224.3 x 10(4), respectively. The high Mw values of the hydroxyethylated and hydroxypropylated derivatives in aqueous solution resulted from aggregation, and their true Mw values obtained in dimethyl sulfoxide were 20.1 x 10(4) and 19.1 x 10(4). The sulfated and carboxymethylated derivatives having DS of 1.0-1.3 show good water solubility, and exist as relatively expanded chains in aqueous solution. Interestingly, the native beta-glucan did not show antitumor activity, whereas the sulfated and carboxymethylated derivatives exhibit significant antitumor activities against S-180 and gastric carcinoma tumor cells. This work showed that good water solubility, relatively high chain stiffness, and moderate molecular mass of the derivatives in aqueous solution contribute beneficial to enhancement of antitumor activity.     

Systems genetic analysis of multivariate response to iron deficiency in mice

The aim of this study was to identify genes that influence iron regulation under varying dietary iron availability. Male and female mice from 20+ BXD recombinant inbred strains were fed iron-poor or iron-adequate diets from weaning until 4 mo of age. At death, the spleen, liver, and blood were harvested for the measurement of hemoglobin, hematocrit, total iron binding capacity, transferrin saturation, and liver, spleen and plasma iron concentration. For each measure and diet, we found large, strain-related variability. A principal-components analysis (PCA) was performed on the strain means for the seven parameters under each dietary condition for each sex, followed by quantitative trait loci (QTL) analysis on the factors. Compared with the iron-adequate diet, iron deficiency altered the factor structure of the principal components. QTL analysis, combined with PosMed (a candidate gene searching system) published gene expression data and literature citations, identified seven candidate genes, Ptprd, Mdm1, Picalm, lip1, Tcerg1, Skp2, and Frzb based on PCA factor, diet, and sex. Expression of each of these is cis-regulated, significantly correlated with the corresponding PCA factor, and previously reported to regulate iron, directly or indirectly. We propose that polymorphisms in multiple genes underlie individual differences in iron regulation, especially in response to dietary iron challenge. This research shows that iron management is a highly complex trait, influenced by multiple genes. Systems genetics analysis of iron homeostasis holds promise for developing new methods for prevention and treatment of iron deficiency anemia and related diseases.     

Characterization of the in vivo and in vitro metabolic profile of PAC-1 using liquid chromatography-mass spectrometry

In the present study, the metabolic profile of PAC-1, a potential anticancer drug, was investigated using liquid chromatography-mass spectrometric (LC/MS) techniques. Two different types of mass spectrometers--a quadrupole time-of-flight (Q-TOF) mass spectrometer and an ion trap (IT) mass spectrometer--were employed to acquire structural information on PAC-1 metabolites. A gradient liquid chromatographic system composed of 0.2% formic acid in methanol and 0.2% formic acid in water was used for metabolite separation on an Agilent TC-C(18) column. A total of 16 metabolites were detected. The corresponding product ion spectra were acquired and interpreted, and structures were proposed. Accurate mass measurement using LC-Q-TOF was used to determine the elemental composition of metabolites thereby confirming the proposed structures of these metabolites. Phase I metabolic changes were predominantly observed, including debenzylation, dihydrodiol formation, hydroxylation, and dihydroxylation. The detected phase II metabolites included PAC-1 and hydroxylated PAC-1 glucuronide conjugates. Based on metabolite analysis, several PAC-1 metabolic pathways in rat were proposed.     

From alpha to beta: identification of amino acids required for the N-acetyllactosamine-specific lectin-like activity of bundlin

Bundle-forming pili (BFP) promote the adherence of typical enteropathogenic Escherichia coli (EPEC) to human intestinal epithelial cells. BFP are polymers of bundlin and nine bundlin alleles have been identified in EPEC isolated from diverse sources. These alleles are divided into two main groups, α and β, based on their amino acid sequences. Alpha bundlins are also N -acetyllactosamine- (LacNAc) specific lectins and bind to HEp-2 cells, whereas β bundlins do not display these characteristics. The four surface-exposed regions of amino acid sequence heterogeneity between α and β bundlin were therefore investigated as potential LacNAc-specific carbohydrate-binding domains in a bundlin. Mutation of one of these domains, 137-GENNI-141, in α₁ bundlin to that of β bundlin (136-SPDST-140) resulted in BFP that no longer bound to LacNAc or HEp-2 cells. Conversely, mutating the β₃ bundlin gene to encode the α bundlin sequence at this domain resulted in the gain of HEp-2 cell adherence. The importance of this domain in carbohydrate binding is supported by the finding that introducing the mutation GENNI→GENNT altered the α₁ bundlin carbohydrate-binding specificity from LacNAc to the Lewis X glycan sequence.     

Molecular mass and chain conformations of Rhizoma Panacis Japonici polysaccharides

The molecular mass and size of five water-soluble polysaccharides isolated from Rhizoma Panacis Japonici (RPJ) were determined with laser light scattering (LLS), size-exclusion chromatography (SEC) combined with LLS (SEC–LLS), dynamic light scattering (DLS), as well as transmission electron microscope (TEM). Their weight-average molecular masses (M_w) were 3.5 × 10⁴, 1.47 × 10⁵, 1.24 × 10⁶, 9.26 × 10⁵ and 1.36 × 10⁶, radii of gyration (<s²>_z^1/2) were 14.7, 31.7, 50.8, 41.8 and 40.4 nm, and hydrodynamic radii (R_h) were 19.9, 37.5, 66.2, 52.1, and 55.2 nm, respectively. The results showed that molecular masses and sizes of the polysaccharides were influenced by the pH and temperature of the extraction mediums. The conformation parameters were calculated from the above data according to polymer solution theory. The values of ρ (= <s²>_z^1/2/R_h) were from 0.7 to 0.8, exponents (ν) of <s²>_z^1/2 = k M_w^ν were from 0.31 to 0.43, and fractal dimension (d_f) were from 2.3 to 3.2, respectively. The results revealed that all of the polysaccharides existed as spheres in 0.15 M NaCl aqueous solution. TEM and atomic force microscope (AFM) further confirmed the spherical morphologies of these molecules. The spherical conformations of the polysaccharides were a result of their highly branched structures.     

Quercetin protected against isoniazide‐induced HepG2 cell apoptosis by activating the SIRT1/ERK pathway

Isoniazid (INH) is one of the most commonly used antituberculosis drugs, but its clinical applications have been limited by severe hepatic toxicity. Quercetin (Que), a natural flavonoid, has been proved to have many medicinal properties. This study aimed to clarify the possible protective effects of Que against INH‐induced hepatotoxicity using HepG2 cells. Our results indicated that Que significantly increased cell viability, superoxide dismutase, and GSH levels, while decreased alanine aminotransferase/aspartate aminotransferase levels. Besides, Que significantly abrogated INH‐induced cell apoptosis by upregulating the expression levels of Bcl‐2 and decreasing the levels of Bax, cleaved caspase‐3, and cleaved caspase‐9. Furthermore, Que obviously reversed the inhibition of INH on Sirtuin 1 (SIRT1) expression and extracellular signal‐regulated kinase (ERK) phosphorylation. Next, the SIRT1 inhibitor EX527 blocked the enhancement of Que upon ERK phosphorylation. Notably, EX527 partially abolished the beneficial effects of Que. In brief, our results provided the first evidence that Que protected against INH‐induced HepG2 cells by regulating the SIRT1/ERK pathway.