Protein Expression of BLM Gene and Its Apoptosis Sensitivity in Hematopoietic Tumor Cell Strains

Patients with Bloom syndrome （BS） show an immunodeficiency, an enhanced sister chromatid exchanges （SCEs）, a strong genetic instability and an increased predisposition to all. In order to investigate the differential expression of BLM protein in hematopoietic tumor cell strains and study the effects of BLM gene on ultraviolet （UV）- or hydroxyurea （HU）-induced apoptosis, Western blot was used to detect the expression of BLM protein in normal human bone marrow mononuclear cells and 4 kinds of hematopoietic tumor cell strains. The 4 kinds of hematopoietic tumor cells were exposed to UV light with a germicidal UV lamp or treated with 2 mmol/L hydroxyurea and the apoptotic rate was detected by using AnnexinV-FITC. The results showed that these tumor cells expressed BLM protein higher than the normal human bone marrow mononuclear cells （P〈0.01）. In the 4 hematopoietic tumor cells, BLM protein was all specially cleaved in response to UV- or HU-induced apoptosis. The increase of BLM protein expression may play an important role in the development of these tumors, and BLM proteolysis is likely to be a general feature of the apoptotic response.

O^6-METHYLGUANINE-DNA METHYLTRANSFERASE ACTIVITY AND SENSITIVITY OF 20 CHINESE TUMOR CELL STRAINS TO 1-(4-AMINO-2-METHYL-5-PYRIMIDINYL) METHYL-3-(2-CHLOROETHYL)-3-NITROSOUREA

O6-methylguanine-DNA methyltransferase (MGMT) plays an important role in repairing alkylated DNA. MGMT activity as well as cellular sensitivity to 1- ( 4- amino- 2-methyl-5-pyrimidinyl) methyl-3- ( 2-chloroethyl)-3-nitrosourea (ACNU) of 20 Chinese tumor cell strains were assayed. A linear response between MGMT activity and ACNU sensitivity (D10) was observed. The lower the MGMT activity In the cells, the more the sensitivity to ACNU killing. It suggested that assay of MGMT activity in tumor biopsy could be used as a guide to predict the effectiveness of ACNU treatment in chemotherapy of human cancer.

Expression of cyclooxygenase-2 mRNA in drug-sensitive cell and drug-resistant strains of ovarian cancer cell lines

Objective： To investigate the expression of cyclooxygenase-2 （COX-2） mRNA in drug-sensitive cell and drugresistant clones of ovarian cancer cell lines. Methods： RT-PCR and immunocytochemistry were used to investigate the expression of cyclooxygenase-2 in 3 clones drug-sensitive and 5 clones drug-resistant ovarian cancer cell. Results： Strong COX-2 mRNA expressions were detected in 3 clones of drug-sensitive cell and weak expressions were detected in 5 clones of drug-resistant cell. The protein expression of COX-2 in drug-sensitive cell was strongly positive reaction in immunocytochemistry stain and there was a weak positive reaction in 5 clones of drug-resistant cell. Conclusion： The expression of COX-2 mRNA in drug-sensitive cell strains is much higher than that in drugresistant strains of ovarian cancer cell lines, providing a basis of the chemoprevention for ovarian cancer.

Effects of serum containing natural cerebrolysin on glucose-regulated protein 78 and CCAAT enhancer-binding protein homologous protein expression in neuronal PC12 cells following tunicamycin-induced endoplasmic reticulum stress

BACKGROUND： Glucose-regulated protein 78 （GRP78）, a marker of endoplasmic reticulum stress, can prolong cell survival. Alternatively, CCAAT enhancer-binding protein homologous protein （CHOP）, a transcription factor specific for endoplasmic reticulum stress, can cause cell cycle arrest and cell apoptosis. OBJECTIVE： To study the protective effects of serum containing natural cerebrolysin on endoplasmic reticulum stress in tunicamycin-induced neuronal PC12 cells, and analyze the influence on GRP78 and CHOP expressions. DESIGN, TIME AND SETTING： A parallel controlled study was performed at the Institute of Integrated Western and Traditional Chinese Medicine, Shenzhen Hospital, Southern Medical University, between March 2006 and August 2008. MATERIALS： Adult Sprague-Dawley rats were perfused with natural Cerebrolysin aqueous extract （0.185 g/kg/d） to produce serum containing natural Cerebrolysin. Physiological saline was used to produce blank serum. PC12 cell line was provided by Shanghai Institute of Cell Biology, Chinese Academy of Science. Tunicamycin was provided by Sigma （St. Louis, USA）, and natural Cerebrolysin, containing ginseng, rhizoma gastrodiae, and gingko leaf （1：2：2）, by Shengzhen Institute of Integrated Western and Traditional Chinese Medicine. METHODS： PC12 cells were treated with DMEM culture media containing 10% blank serum （normal control group）, tunicamycin （1 μg/mL; model group）, and 5%, 10%, and 15% serum containing natural cerebrolysin and tunicamycin （1 μ g/mL; low-, moderate-, and high-dose serum containing natural cerebrotysin groups）, for 2 hours. MAIN OUTCOME MEASURES： PC12 cells were treated with tunicamycin for 48 hours after which apoptosis was measured using the TUNEL method to calculate apoptotic index. GRP78 expression was detected using immunocytochemistry. After 24 hours of treatment with tunicamycin, GRP78 and CHOP mRNA expressions were measured using RT-PCR. RESULTS： The apoptotic index and CHOP mRNA expression were in the model group and three cerebrolysin groups were significantly increased when compared to the normal control group （P 〈 0.05）. In contrast, GRP78 mRNA and protein expressions were significantly decreased （P 〈 0.05）. CONCLUSION： Serum containing natural cerebrolysin significantly reduced apoptosis in neuronal PC12 cells following tunicamycin-induced endoplasmic reticulum stress. These results may be related to an up-regulation of GRP78 expression and down-regulation of CHOP expression, both of which displayed dose-dependent effects.

Inhibitory effect of Fuzheng Yiliuyin in combination with chemotherapeutics on human gastric carcinoma cell strain

AIM： To study the inhibitory effects of Fuzheng Yiliuyin （Decoction for Suppressing Tumors by Strengthening the Body Resistance） in combination with chemotherapeutics on human gastric carcinoma cell strain. METHODS： Fuzheng Yiliuyin （ZY） combined with various kinds of chemotherapeutics was put into two kinds of cultivated human gastric carcinoma cell strains, then its inhibitory effects on human gastric carcinoma cell strains were determind by the MTT method. Flow cytorneter was used to assay the apoptosis rate, and the ultrastructure of gastric carcinoma cells was observed under transmission electron microscope. RESULTS： Obvious apoptosis was seen in gastric carcinoma cells after treatment with ZY for 72 h. ZY and chemical drugs had synergistic inhibition effects on the cultivated gastric carcinoma cells, but the effects were different on various cell strains. The inhibitory effects of ZY could be strengthened by cytotoxic action and apoptosis. ZY combined with tluorouracil, etoposide and cisplatin （EFP） chemotherapeutics had better inhibitory effects on SGC-7901, while ZY combined with EFP or with DDP chemotherapeutics had better inhibitory effects than other drugs on MGC-803. CONCLUSION： ZY induces apoptosis and inhibits the growth of gastric carcinoma cells. ZY has the synergistic function of chemotherapeutics.

GENOTOXIC EFFECT OF CIGARETTE SMOKE CONDENSATE (CSC) ON HUMAN DIPLOID CELL 2BS STRAIN

A series of bioassays such as sister chromatid exchange frequencies ( SCE.), chromosomal aberration ( CA ), micronuclel rate (MN) and cell-cycle delay have been used to detecting the genotoxic effect of cigarette smoke condensate (CSC) on human diploid cell 2BS strain. The results suggested that a higher SCE, ( 17. 0/ cell) was observed In 2BS cells treated with CSC at 100 μg/ml, as compared with 6. 9/cell of the background (P<0. 001). CA rate was significantly increased from 4% to 36% In cells treated with 10 μg/ml CSC (P< 0.001). MN rate varied from 9 -26‰ In cells treated with CSC compared to that of control (6‰). Meanwhile, the cell-cycle of cells was markedly delayed by CSC. The survival rate of 2BS cells declined to 59. 6% for treatment with CSC at 200 μg/ ml. There was a dose-effect response In SCE., CA, MN rate. We proposed that active oxygen might responsible for genotoxiclty of CSC on cells.

Immortalized Rat Astrocyte Strain Genetically Modified by Rat Preprogalanin Gene

Summary: To construct an immortalized rat astrocyte strain genetically modified by rat preprogalanin gene (IAST/GAL) and detect its galanin (GAL) expression and secretion, a cDNA fragment of rat GAL in plasmid of pBS KS(+)-GAL was inserted into eukaryotic expression vector pcDNA3.1(+) by DNA recombinant technology, then the restriction enzyme digestion and DNA sequencing were carried out to evaluate the recombinant. The pcDNA3.1(+)-GAL and pcDNA3.1(+) construct were transfected into immortalized rat astrocyte strain (IAST) by lipofectamine and the population of cells which stably integrated the construct was selected with 600 μg/mL G418. Individual clones were screened and expanded into clonal cell strains. Detection of Neo gene was used to validate the success of the transfection. Immunocytochemical staining, RT-PCR and radioimmunoassay were used to detect the expression and secretion level of GAL. The recombinant had been successfully constructed by restriction enzyme digestion and DNA sequencing. Detection of Neo gene showed that the pcDNA3.1(+)-GAL and pcDNA3.1(+) have been successfully transfected into IAST. After selection by using G418, IAST/GAL and IAST/Neo cell strains were obtained. IAST/GAL, IAST/Neo and IAST were immunostained positively for GAL, but the GAL average optical density of IAST/GAL was significantly higher than that of IAST/Neo and IAST (P< 0.01). The level of GAL mRNA expression and the supernatant concentration of GAL in cultured IAST/GAL were significantly higher than those of IAST and IAST/Neo (P<0.01), but no significant differences were found between the IAST and IAST/Neo (P>0.05). It was concluded that IAST/GAL strain was constructed successfully and it might provide a basis for the further study of pain therapy.

Cell membrane tensile strain under cyclic compression:A viscoelastic myoblast finite element model

Cyclic mechanical stimulation could lead to subsequent biomechanical and biological effects on cells.Viscoelastic cells could deform or show energy dissipation with hysteresis behavior in response to external cyclic compression.The aim of this study was to investigate the effect of cyclic compression on a single viscoelastic myoblast through a confocal–based cell–specific finite element model,including cell membrane tensile strain and damaged elements.Sinusoidal compression was applied to the apical surface of the myoblast(cell membrane)with compressive stress of 500
500 Pa(with stress offset at 500 Pa and amplitude of 500 Pa)at 0 Hz(static compression of 500 Pa),0.25 Hz,0.5 Hz,0.75 Hz,1 Hz,5 Hz,and 10 Hz.Results showed that the ratio of average tensile strain integral in all cell membrane elements over a certain period of time(T)to that duration(T)(MAS index)decreased under cyclic compression compared to that of static compression in the short term(within 4 s).Furthermore,compared to static compression,the percentage of damaged elements of cell membrane under cyclic compression decreased assuming a 3%cell membrane tensile strain damage threshold.The optimal cyclic compression frequency 0.25 Hz led to the largest difference of MAS index under cyclic compression and static compression.These results may provide support for the application of cyclic compressive stimulation in the prevention of cell damage.