Reduction of tumorigenicity of SMMC-7721 hepatoma cells by vascular endothelial growth factor antisense gene therapy

AIM: To test the hypothesis to block VEGF expression of SMMC-7721 hepatoma cells may inhibit tumor growth using the rat hepatoma model. METHODS: Amplify the 200 VEGF cDNA fragment and insert it into human U6 gene cassette in the reverse orientation transcribing small antisense RNA which could specifically interact with VEGF165, and VEGF121 mRNA. Construct the retroviral vector containing this antisense VEGF U6 cassette and package the replication-deficient recombinant retrovirus. SMMC-7721 cells were transduced with these virus and positive clones were selected with G418. PCR and Southern blot analysis were performed to determine if U6 cassette integrated into the genomic DNA of positive clone. Transfected tumor cells were evaluated for RNA expression by ribonuclease protection assays. The VEGF protein in the supernatant of parental tumor cells and genetically modified tumor cells was determined with ELISA. In vitro and in vivo growth properties of antisense VEGF cell clone in nude mice were analyzed. RESULTS: Restriction enzyme digestion and PCR sequencing verified that the antisense VEGF RNA retroviral vector was successfully constructed.After G418 selection, resistant SMMC-7721 cell clone was picked up. PCR and Southern blot analysis suggested that U6 cassette was integrated into the cell genomic DNA. Stable SMMC-7721 cell clone transduced with U6 antisense RNA cassette could express 200 bp small antisense VEGF RNA and secrete reduced levels of VEGF in culture condition. Production of VEGF by antisense transgene-expressing cells was 65+/-10 ng/L per 10(6) cells, 42045 ng/L per 10(6) cells in sense group and 485+/-30 ng/L per 10(6) cells in the negative control group, (P【 0.05). The antisense-VEGF cell clone appeared phenotypically indistinguishable from SMMC-7721 cells and SMMC-7721 cells transfected sense VEGF. The growth rate of the antisense-VEGF cell clone was the same as the control cells. When S.C. was implanted into nude mice, growth of antisense-VEGF cell lines was greatly inhibited compared with control cells. CONCLUSION: Expression of antisense VEGF RNA in SMMC-7721 cells could decrease the tumorigenicity, and antisense-VEGF gene therapy may be an adjuvant treatment for hepatoma.

Applying a highly specific and reproducible cDNA RDA method to clone garlic up-regulated genes in human gastric cancer cells

AIM: To develop and optimize cDNA representational difference analysis (cDNA RDA) method and to identify and clone garlic up-regulated genes in human gastric cancer (HGC) cells. METHODS: We performed cDNA RDA method by using abundant double-stranded cDNA messages provided by two self-constructed cDNA libraries (Allitridi-treated and paternal HGC cell line BGC823 cells cDNA libraries respectively). Bam H I and Xho I restriction sites harbored in the library vector were used to select representations. Northern and Slot blots analyses were employed to identify the obtained difference products. RESULTS: Fragments released from the cDNA library vector after restriction endonuclease digestion acted as good marker indicating the appropriate digestion degree for library DNA. Two novel expressed sequence tags (ESTs) and a recombinant gene were obtained. Slot blots result showed a 8-fold increase of glia-derived nexin/protease nexin 1 (GDN/PN1) gene expression level and 4-fold increase of hepatitis B virus x-interacting protein (XIP) mRNA level in BGC823 cells after Allitridi treatment for 72h. CONCLUSION: Elevated levels of GDN/PN1 and XIP mRNAs induced by Allitridi provide valuable molecular evidence for elucidating the garlic's efficacies against neurodegenerative and inflammatory diseases. Isolation of a recombinant gene and two novel ESTs further show cDNA RDA based on cDNA libraries to be a powerful method with high specificity and reproducibility in cloning differentially expressed genes.

Effect of 5-Aza-2'-deoxycytidine on the P16 tumor suppressor gene in hepatocellular carcinoma cell line HepG2

INTRODUCTIONHepatocellular carcinoma (HCC) is one of the mostcommon human malignancies worldwide[1,2], and isclosely associated with infection of HBV and HCVand contamination of aflatoxin B1[3-6]. Althoughthe molecular mechanisms of hepatocarcinogenesisremain poorly understood, an increasing number ofgenetic abnormalities have been recognized[7-10],for example, the p16 gene[11,12] the p53gene[13-18], the E-cadherin gene[19], and the c-mycgene[20].

Adeno-associated virus mediated endostatin gene therapy in combination with topoisomerase inhibitor effectively controls liver tumor in mouse model

AIM:rAAV mediated endostatin gene therapy has been examined as a new method for treating cancer.However, a sustained and high protein delivery is required to achieve the desired therapeutic effects.We evaluated the impact of topoisomerase inhibitors in rAAV delivered endostatin gene therapy in a liver tumor model. METHODS:rAAV containing endostatin expression cassettes were transduced into hepatoma cell lines.To test whether the topoisomerase inhibitor pretreatment increased the expression of endostatin,Western blotting and ELISA were performed.The biologic activity of endostatin was confirmed by endothelial cell proliferation and tube formation assays. The anti-tumor effects of the rAAV-endostatin vector combined with a topoisomerase inhibitor,etoposide,were evaluated in a mouse liver tumor model. RESULTS:Topoisomerase inhibitors,including camptothecin and etoposide,were found to increase the endostatin exPression level in vitro.The over-expressed endostatin, as a result of pretreatment with a topoisomerase inhibitor, was also biologically active.In animal experiments,the combined therapy of topoisomerase inhibitor,etoposide with the rAAV-endostatin vector had the best tumor- suppressive effect and tumor foci were barely observed in livers of the treated mice.Pretreatment with an etoposide increased the level of endostatin in the liver and serum of rAAV-endostatin treated mice.Finally,the mice treated With rAAV-endostatin in combination with etoposide showed the longest survival among the experimental models. CONCLUSION:rAAV delivered endostatin gene therapy in combination with a topoisomerase inhibitor pretreatment is an effective modality for anticancer gene therapy.

Retrovirus-mediated herpes simplex virus thymidine kinase gene therapy approach for hepatocellular carcinoma

The therapeutic effect of herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system on hepatocellular carcinoma was studied in this experiment. The tk-containing retroviral recombinants were used to infect hepatoma cells (BEL-7402) and the cells were treated with ganciclovir (0-1000 microg/ml). The results showed that HSV-tk gene could be efficiently transferred in vitro into hepatoma cells and stably expressed. The growth potential of the tk-containing cells was significantly inhibited by GCV (P

Specific CEA-producing colorectal carcinoma cell killing with recombinant adenoviral vector containing cytosine deaminase gene

AIM: To kill CEA positive colorectal carcinoma cells specifically using the E coli cytosine deaminase (CD) suicide gene, a new replication-deficient recombinant adenoviral vector was constructed in which CD gene was controlled under CEA promoter and its in vitro cytotoxic effects were evaluated. METHODS: Shuttle plasmid containing CD gene and regulatory sequence of the CEA gene was constructed and recombined with the right arm of adenovirus genome DNA in 293 cell strain. Dot blotting and PCR were used to identify positive plaques. The purification of adenovirus was performed with ultra-concentration in CsCl step gradients and the titration was measured with plaque formation assay. Cytotoxic effects were assayed with MTT method, The fifty percent inhibition concentration (IC(50)) of 5-FC was calculated using a curve-fitting parameter. The human colorectal carcinoma cell line, which was CEA-producing, and the CEA-nonproducing Hela cell line were applied in cytological tests. An established recombinant adenovirus vector AdCMVCD, in which the CD gene was controlled under CMV promoter, was used as virus control. Quantitative results were expressed as the mean +/- SD of the mean. Statistical analysis was performed using ANOVA test. RESULTS: The desired recombinant adenovirus vector was named AdCEACD. The results of dot blotting and PCR showed that the recombinant adenovirus contained CEA promoter and CD gene. Virus titer was about 5.0 X 10(14)pfu/L(-1) after purification. The CEA-producing Lovo cells were sensitive to 5-FC and had the same cytotoxic effect after infection with AdCEACD and AdCMVCD (The IC(50) values of 5-FC in parent Lovo cells, Lovo cells infected with 100 M.O.I AdCEACD and Lovo cells infected with 10 M.O.I AdCMVCD were 】15000, 216.5+/-38.1 and 128.8+/-25.4 micromol.L(-1), P【0.001, respectively), and the cytotoxicity of 5-FC increased accordingly when the m.o.i of adenoviruses were enhanced (The value of IC(50) of 5-FC was reduced to 27.9+/-4.2 micromol.L(-1) in 1000 M.O.I AdCEACD infected Lovo cells and 24.8+/-7.1 micromol.L(-1) in 100 M.O.I AdCMVCD infected Lovo cells, P【0.05, P【0.01, respectively). The CEA-nonproducing Hela cells had no effect after infection with AdCEACD, but Hela cells had the cytotoxic sensitivity to 5-FC after infection with AdCMVCD (The IC(50) of 5-FC in parent Hele cells and Hela cells infected with AdCMVCD at 10 M.O.I was 】15000 and 214.5+/-31.3 micromol.L(-1), P【0.001). AdCEACD/5-FC system also had bystander effect, and the viability was about 30 percent when the proportion of transfected cells was only 10 percent. CONCLUSION: The recombinant adenovirus vector AdCEACD has the character of cell type-specific gene delivery. The AdCEACD/5-FC system may become a new, potent and specific approach for the gene therapy of CEA-positive neoplasms, especially colon carcinoma.

Expression of vascular endothelial growth factor and its role in oncogenesis of human gastric carcinoma

AIM: To establish the role of vascular endothelial growth factor (VEGF) in the oncogenesis of human gastric carcinoma more directly. METHODS: The expression of VEGF and its receptor kinase-domain insert containing receptor (KDR) in human gastric cancer tissue were observed by immunohistochemical staining. VEGF levels were manipulated in human gastric cancer cell using eukaryotic expression constructs designed to express the complete VEGF(165) complimentary DNA in either the sense or antisense orientation. The biological changes of the cells were observed in which VEGF was up-regulated or down-regulated. RESULTS: VEGF-positive rate was 50%, and VEGF was mainly localized in the cytoplasm and membrane of the tumor cells, while KDR was mainly located in the membrane of vascular endothelial cells in gastric cancer tissues and peri-cancerous tissue. In 2 cases of 50 specimens, the gastric cancer cells expressed KDR, localized in both the cytoplasm and membrane. Introduction of VEGF(165) antisense into human gastric cancer cells (SGC-7901, immunofluorescence intensity, 31.6%)) resulted in a significant reduction in VEGF-specific messenger RNA and total and cell surface VEGF protein (immunofluorescence intensity, 8.9%) (P【0.05). Conversely, stable integration of VEGF(165) in the sense orientation resulted in an increase in cellular and cell surface VEGF (immunofluorescence intensity, 75.4%) (P【0.05). Lowered VEGF levels were associated with a marked decrease in the growth of nude mouse xenografted tumor (at 33 days postimplantation, tumor volume: 345.40 +/- 136.31 mm3)(P【0.05 vs control SGC-7901 group: 1534.40 +/- 362.88 mm3), whereas up-regulation of VEGF resulted in increased xenografted tumor size (at 33 days postimplantation, tumor volume: 2350.50 +/- 637.70 mm3) (P【0.05 vs control SGC-7901 group). CONCLUSION: This study provides direct evidence that VEGF plays an important role in the oncogenesis of human gastric cancer.

Killing effect of TNF-related apoptosis inducing ligand regulated by tetracycline on gastric cancer cell line NCI-N87

AIM: To clone the cDNA fragment of human TRAIL (TNF-related apoptosis inducing ligand) into a tetracycline-regulated gene expression system, the RevTet-On system, transduce expression vectors into a gastric carcinoma cell line-NCI-N87 and examine the effects of controlled expression of TRAIL in vitro on the gastric carcinoma cells. METHODS: The full-length cDNA of TRAIL was inserted into a vector under the control of the tetracycline-responsive element (TRE) to obtain the plasmid pRevTRE-TRAIL, which was transfected into a packaging cell line PT67. In addition, vector pRev-Tet On and pRevTRE were also transfected into PT67 separately. After hygromycin and G418 selection, the viral titer was determined. The medium containing retroviral vectors was collected and used to transduce a gastric carcinoma cell line NCI-N87. The resulting cell line NCI-N87-Tet On TRE-TRAIL and a control cell line, NCI-N87 Tet On-TRE, were established. TRAIL expression in the cell line was induced by incubating cells with doxycycline (Dox), which is a tetracycline analogue. The killing effect on gastric carcinoma cells was analyzed after induction. RESULTS: The recombinant plasmid pRev-TRE-TRAIL was constructed. After hygromycin or G418 selection, the producer cell lines PT67-TRE, PT67-TRE-TRAIL and PT67-Tet On were obtained,with titers of about 10(8)CFU.L(-1). By transducing NCI-N87 cells with retroviral vectors from these cell lines, stable cell lines NCI-N87-Tet-On TRE-TRAIL (NN3T) and control cell line NCI-N87-Tet-On-TRE (NN2T) were established. The growth curves of the selected cell lines were the same with the wild type NCI-N87. When Dox was added, cell death was obvious in the test groups (29%-77%), whereas no difference was observed in control and wild type cell lines. With the addition of a medium from the test group, human leukemia cell line Jurkat was activated till death (83%), indicating the secretion of active TRAIL proteins from the test cells to the medium. CONCLUSION: With the use of the RevTet-On system, a regulated expression system for TRAIL was constructed. Using this system, the selected killing effect of TRAIL on gastric carcinoma cell line NCI-N87 could be observed.

Sequencing of p53 mutation in established human hepatocellular carcinoma cell line of HHC4 and HHC15 in nude mice

AIM To set up cell lines of human hepatocellular carcinoma in nude mice for the research of cell biology and gene therapy. METHODS Xenotransplantation of human hepatoma into nude mice was carried out and the growth rate, histopathology and immunology of the nude mice were studied. The DNA from xenografts were analyzed by HBV gene and PCR amplification of a fragment of p 53 gene exon 7, which were identified by dot blot hybridization, restriction fragments length polymorphism and DNA sequencing. RESULTS hHCC4 and hHCC415 cell lines could be successively transplanted in nude mice and the population doubling time was 7 and 5 days respectively. These strains retained the original characteristics of histopathology, secreting AFP and heteroploid karyotypes in human hepatocellular carcinoma. The fragment of HBV gene was detected in the genomic DNA of both hHCC4 and hHCC15, however only hHCC4 secreted HBsAg. The mutation at 250 code (C→A) and 249 code (G→T) were detected respectively in the genomic DNA of hHCC4 and hHCC15. CONCLUSION The two cell lines are useful material for studying cell biology and gene therapy in human hepatocellular carcinoma and provide molecular biological trace of the relationship between high mortality of hepatoma and AFB1 severe pollution of the daily common foods in this district.

Inhibition of human telomerase in MKN-45 cell line by antisense hTR expression vector induces cell apoptosis and growth arrest

AIM: To investigate the effects of antisense human telomerase RNA (hTR)on the biologic behavior of human gastric cancer cell line: MKN-45 by gene transfection and its potential role in the gene therapy of gastric cancer. METHODS: The hTR cDNA fragment was cloned from MKN-45 through RT-PCR and subcloned into eukaryotic expression vector (pEF6/V5-His-TOPO) in cis-direction or trans-direction by DNA recombinant methods. The constructed sense, antisense and empty vectors were transfected into MKN-45 cell lines separately by lipofectin-mediated DNA transfection technology. After drug selection, the expression of antisense hTR gene in stable transfectants and normal MKN-45 cells was detected by RT-PCR, the telomerase activity by TRAP, the apoptotic features by PI and Hoechst 33258 staining, the cell cycle distribution by flow cytometry and the population doubling time by cell counting. Comparison among the stable transfectants and normal MKN-45 cells was made. RESULTS: The sense, antisense hTR eukaryotic expression vectors and empty vector were successfully constructed and proved to be the same as original design by restriction endonuclease analysis and sequencing. Then, they were successfully transfected into MKN-45 cell lines separately with lipofectin. The expression of antisense hTR gene was only detected in MKN-45 cells stably transfected with antisense hTR vector (named as MKN-45-ahTR) but not in the control cells. In MKN-45-ahTR, the telomerase activity was inhibited by 75%, the apoptotic rate was increased to 25.3%, the percentage of cells in the G0/G1 phase was increased to 65%, the proliferation index was decreased to 35% and the population doubling time was prolonged to 35.3 hours. However, the telomerase activity, the apoptotic rate, the distribution of cell cycle, the proliferation index and the population doubling time were not different among the control cells. CONCLUSION: Antisense hTR can significantly inhibit telomerase activity and proliferation of MKN-45 cells and induce cell apoptosis. Antisense gene therapy based on telomerase inhibition can be a potential therapeutic approach to the treatment of gastric cancer.

The effect of adenovirus expressing wild-type p53 on 5-fluorouracil chemosensitivity is related to p53 status in pancreatic cancer cell lines

AIM:There are conflicting data about p53 function on cellular sensitivity to the cytotoxic action of 5-fluorouracil (5-FU). Therefore the objective of this study was to determine the combined effects of adenovirus-mediated wild-type (wt) p53 gene transfer and 5-FU chemotherapy on pancreatic cancer cells with different p53 gene status. METHODS:Human pancreatic cancer cell lines Capan-1^(p53mut), Capan-2^(p53wt),FAMPAC^(p53mut),PANC1^(p53mut),and rat pancreatic cancer cell lines AS^(p53wt) and DSL6A^(p53null) were used for in vitro studies.Following infection with different ratios of Ad- p53-particles (MOI) in combination with 5-FU,proliferation of tumor cells and apoptosis were quantified by cell proliferation assay (WST-1) and FACS (PI-staining).In addition,DSL6A syngeneic pancreatic tumor cells were inoculated subcutaneously in to Lewis rats for in vivo studies. Tumor size,apoptosis (TUNEL) and survival were determined. RESULTS:Ad-p53 gene transfer combined with 5-FU significantly inhibited tumor cell proliferation and substantially enhanced apoptosis in all four cell lines with an alteration in the p53 gene compared to those two cell lines containing wt-p53.In vivo experiments showed the most effective tumor regression in animals treated with Ad-p53 plus 5-FU.Both in vitro and in vivo analyses revealed that a sublethal dose of Ad-p53 augmented the apoptotic response induced by 5-FU. CONCLUSION:Our results suggest that Ad-p53 may synergistically enhance 5-FU-chemosensitivity most strikingly in pancreatic cancer cells lacking p53 function.These findings illustrate that the anticancer efficacy of this combination treatment is dependent on the p53 gene status of the target tumor cells.

Blockage of IGF-1R signaling sensitizes urinary bladder cancer cells to mitomycin-mediated cytotoxicity

A major problem which is poorly understood in the management of bladder cancer is low sensitivity to chemotherapy and high recurrence after transurethral resection. Insulin-like growth factor 1 receptor (IGF-1R) signaling plays a very important role in progression, invasion and metastasis of bladder cancer cells. In this study, we investigated whether IGF-1R was involved in the growth stimulating activity and drug resistance of bladder cancer cells. The results showed: The mRNAs of IGF-1, IGF-2 and IGF-1R were strongly expressed in serum-free cultured T24 cell line, whereas normal urothelial cells did not express these factors/receptors or only in trace levels; T24 cell responded far better to growth stimulation by IGF-1 than did normal urothelial cells; blockage of IGF1R by antisense oligodeoxynucleotide (ODN) significantly inhibited the growth of T24 cell and enhanced sensitivity and apoptosis of T24 cells to mitomycin (MMC). These results suggested that blockage of IGF-IR signaling might potentially contribute to the treatment of bladder cancer cells which are insensitive to chemotherapy.

Differential expression of a novel colorectal cancer differentiation-related gene in colorectal cancer

AIM: To investigate SBA2 expression in CRC cell lines and surgical specimens of CRC and autologous healthy mucosa. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used for relative quantification of SBA2 mRNA levels in 4 human CRC cell lines with different grades of differentiation and 30 clinical samples. Normalization of the results was achieved by simultaneous amplification of beta-actin as an internal control. RESULTS: In the exponential range of amplification, fairly good linearity demonstrated identical amplification efficiency for SBA2 and beta-actin (82%). Markedly lower levels of SBA2 mRNA were detectable in tumors, as compared with the coupled normal counterparts P【0.01). SBA2 expression was significantly (0.01】P 【 0.05) correlated with the grade of differentiation in CRC, with relatively higher levels in well-differentiated samples and lower in poorly-differentiated cases. Of the 9 cases with lymph nodes affected, 78% (7/9) had reduced SBA2 mRNA expression in contrast to 24% (5/21) in non-metastasis samples 0.01】P【0.05). CONCLUSION: SBA2 gene might be a promising novel biomarker of cell differentiation in colorectal cancer and its biological features need further studies.

Relationship between Fas/ FasL expression and apoptosis of colon adenocarcinoma cell lines

INTRODUCTIONFas/ FasL system has been identified as a keymediator of apoptosis in tumor cells[1-4]. Theoccurrence and development of neoplasm are closelyrelated to apoptosis[5-7] Most chemotherapeuticdrugs kill cancer cells mainly by inducingapoptosis[8-14].'

Gene-viral vectors: a promising way to target tumor cells and express anticancer genes simultaneously

OBJECTIVE: To develop a new kind of vector system called gene-viral vector, which combines the advantages of gene and virus therapies. METHODS: Using recombinant technology, an anti-tumor gene was inserted into the genome of replicative virus specific for tumor cells. The cell killing effect, reporter gene expression of the green fluorescence protein, anti-tumor gene expression of mouse interleukin-12 (mIL-12) and replication of virus were observed by the methods of cell pathology, fluorescence microscopy, ELISA and electron microscopy, respectively. RESULTS: A new kind of gene-viral vector system of adenovirus, in which the E1b-55 kD gene was deleted but the E1a gene was preserved, was constructed. The vector system, like the replicative virus ONYX-015, replicated and proliferated in tumor cells but not in normal ones. Our vector had an advantage over ONYX-015 in that it carried different kinds of anti-tumor genes to enhance its therapeutic effect. The reporter gene expression of the green fluorescence protein in tumor cells was much better than the adenovirus vector employed in conventional gene the rapy, and the expression in our vector system was as low as or even less than that in the conventional adenovirus gene therapy system. Similar results were observed in experiments with this vector system carrying the anti-tumor gene mIL-12. Replication and proliferation of the virus carrying the mIL-12 gene in tumor cells were confirmed by electron microscopy. CONCLUSIONS: Gene-viral vectors are new vectors with an anti-tumor gene inserted into the genome of replicative virus specific for tumor cells. Because of the specific replication and proliferation of the virus in tumor cells, expression of the anti-tumor gene is increased hundreds to thousands of times. This approach takes full advantages of gene therapy and virus therapy to enhance the effect on the tumor. It overcomes the disadvantages of conventional gene therapy, such as low transfer rate, low gene expression, lack of target tropism, and low anti-tumor activity. We believe that this is a promising means for future tumor treatment.

人增殖抑制基因(HSG)对肿瘤细胞系化疗敏感性的作用

目的:将人增殖抑制基因 (hHSG)用电子穿孔的转基因方式转染到体外培养的人肿瘤细胞系中,观察hHSG基因对内源性hHSG表达水平不同的肿瘤细胞系的化疗敏感性的影响。方法:首先用免疫组化方法检测不同组织来源的肿瘤细胞系中hHSG的表达水平,然后选择内源性hHSG表达水平较低的肺腺癌 (A549 )和内源性hHSG表达水平较高的宫颈癌(HeLaS3)细胞系,用电穿孔方法转染含有hHSG的真核表达载体 (pEGFP hHSG) 24h后,加入放线菌酮(CHX),采用细胞计数、MTT法观察hHSG对肿瘤细胞增殖抑制作用及对CHX的化疗敏感性的影响。结果:hHSG在不同组织来源的肿瘤细胞系都有不同程度的表达, pEGFP hHSG转染到两种内源性hHSG表达水平不同的肿瘤细胞系后,这两种肿瘤细胞的生长增殖都明显受到抑制,同时外源性的hHSG也增强了这些肿瘤细胞系对CHX的敏感性。结论:外源性hHSG可不依赖其内源性表达水平而抑制肿瘤细胞的增殖,与CHX并用可增强肿瘤细胞对CHX的敏感性,具有协同作用。

山奈酚对大鼠肝癌细胞CBRH7919的增殖抑制及诱导凋亡作用

【目的】观察山奈酚对大鼠肝癌细胞CBRH7919增殖抑制、诱导凋亡和细胞周期的影响。【方法】选用CBRH7919肝癌细胞株,传代培养24 h后,加入不同浓度山奈酚处理,采用四甲基偶氮唑盐(MTT)法检测细胞存活率,4,′6-二脒基-2-苯基吲哚(DAPI)染色观察细胞凋亡形态,彗星电泳技术和流式细胞术检测药物对细胞DNA的作用。【结果】山奈酚体外能抑制大鼠肝癌细胞CBRH7919的增殖,以6.25、12.5、25、50、100μmol/L浓度的山奈酚处理细胞72 h,对CBRH7919细胞的增殖抑制率显著升高,呈明显的剂量效应关系。用50、100μmol/L浓度的山奈酚作用于细胞24、48、72、96 h,对细胞的增殖抑制作用显著增强,呈明显的时间效应关系,即药物作用时间越长,抑制作用越强。DAPI染色显示不同浓度山奈酚组的细胞均有明显的细胞凋亡特征。彗星电泳显示30、60、120μmol/L浓度的山奈酚作用于细胞72 h后,细胞后面均呈现长度不等的拖尾,平均光密度值较空白对照组显著降低(P<0.01),彗星尾距较空白对照组显著增加(P<0.01),且两者改变与药物浓度相关。流式细胞仪检测结果显示30、60、120μmol/L浓度的山奈酚作用于细胞72 h出现亚二倍体凋亡峰,细胞周期被阻滞于S期,不同浓度山奈酚组凋亡率较空白对照组均明显增高。【结论】山奈酚可能通过抑制大鼠肝癌细胞CBRH7919的增殖及诱导其凋亡而产生抗肿瘤作用。

三氧化二砷对人胃癌细胞诱导分化的实验

目的 在三氧化二砷 (As2 O3)诱导凋亡的基础上 ,探讨低浓度 As2 O3对胃癌细胞诱导分化的作用。方法 以0 .5μmol的 As2 O3处理人胃癌细胞株 SGC790 1和 MKN45 ,观察癌细胞增殖情况 ;经流式细胞仪检测细胞周期 ;用免疫组化法检测部分基因表达变化。结果 As2 O3处理后 :1癌细胞增殖减缓 ,传至 16代后停止增殖 ;2 48小时后开始 ,G1 / G0 期细胞比例增加 ,S期细胞比例减少 ;3p5 3和 bcl- XL基因表达率降低 ,Bax基因表达率上升 ,bcl- 2表达不改变。结论 低浓度 As2 O3有诱导胃癌细胞株分化作用 。

自杀基因系统联合六味地黄丸对肝癌细胞杀伤的协同作用

【目的】观察六味地黄丸含药血清协同HSV-tk/GCV自杀基因治疗系统杀伤大鼠肝癌CBRH7919细胞的作用,探讨建立自杀基因联合中药方药的肿瘤基因治疗联合方案的可行性。【方法】构建HSV-tk/GCV自杀基因治疗系统,确定丙氧鸟苷(GCV)工作浓度(39.2μmol/L);选用SD大鼠灌胃制备六味地黄丸含药血清和空白血清,并观察含药血清和空白血清对肿瘤细胞生长的影响。设空白对照组、GCV对照组、自杀基因治疗对照组,以上3组均为无大鼠血清的对照组。空白血清组、GCV加空白血清组、自杀基因系统加空白血清组、含药血清组、GCV加含药血清组、自杀基因系统联合含药血清组中,所有大鼠的空白血清和含药血清再分为体积分数5%和7.5%2种浓度,每组设6个复孔。将大鼠肝癌细胞CBRH7919/tk+和CBRH7919/tk-混合,使tk+细胞的比例分别占0%、5%、10%,按3×103个/孔细胞分别接种到96孔板,用完全培养基培养细胞24h后,相应加入体积分数5%或7.5%的大鼠空白血清和含药血清,孵育12h,加入GCV,培养60h,四甲基偶氮唑盐(MTT)法检测细胞存活率,用Q值(实测药效与理论药效的比值)分析自杀基因系统与含药血清联合的相互作用是否具有协同性(0.85≤Q<1.15为相加作用,Q≥1.15为协同作用)。【结果】空白血清和含药血清浓度在体积分数20%以下时未显示明显细胞毒性;血清浓度为体积分数5%和7.5%时,自杀基因系统联合含药血清组与单独含药血清组及自杀基因系统加空白血清组比较,联合组对肿瘤细胞的杀伤作用均强于其他非联合组,细胞存活率均有显著性差异(P<0.01),而且自杀基因系统联合含药血清的作用具有明显的协同性(Q>1.15)。【结论】HSV-tk/GCV自杀基因治疗系统联合六味地黄丸对杀伤肿瘤细胞具有协同增效作用。

六味地黄丸含药血清调控黑色素瘤B16细胞株缝隙连接蛋白表达的作用

【目的】观察六味地黄丸含药血清调控小鼠黑色素瘤B16细胞株缝隙连接蛋白(Cx)表达的作用。【方法】采用SD大鼠灌胃8 d制备六味地黄丸含药血清(药物剂量为32 g.kg-1.d-1)和对照血清(灌胃等容积生理盐水);选择对B16细胞生长和形态影响不大的血清浓度(体积分数为10%)作为大鼠血清的工作浓度;采用Western blot技术和间接免疫荧光法及流式荧光法检测六味地黄丸含药血清对黑色素瘤B16细胞株缝隙连接蛋白(Cx26/30/32)表达的影响。【结果】Western blot检测显示空白组(无鼠血清)3种Cx几乎不表达,而对照血清和六味地黄丸各浓度含药血清均能提高Cx蛋白的表达,但含药血清的作用更为明显且有显著的量效关系;间接它被荧光法和流式荧光法检测显示类似的结果:对照血清组和中、高剂量含药血清组的Cx蛋白荧光强度均较空白组显著增加(P<0.01),但与对照血清组比较,只有高剂量含药血清组荧光强度显著增加(P>0.05),低剂量含药血清组Cx蛋白表达反而下降(P<0.01)。【结论】六味地黄丸含药血清具有调控小鼠黑色素瘤B16细胞株缝隙连接蛋白表达的作用。