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.

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].

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].'

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.

Influence of L-methionine-deprived total parenteral nutrition with 5-fluorouracil on gastric cancer and host metabolism

AIM: To investigate the influence of L-methionine-deprived total parenteral nutrition with 5-FU on gastric cancer and host metabolism. METHODS: N-methyl-N'-nitro-nitrosoguanidine (MNNG) induced gastric cancer rats were randomly divided into four groups: Met-containing TPN group (n=11), Met-deprived TPN group (n =12), Met-containing TPN+5-FU group (n=11) and Met-deprived TPN+5-FU group (n=12). Five rats in each group were sacrificed after 7 days of treatment and the samples were taken for examination. The remaining rats in each group were then fed separately with normal diet after the treatment until death, the life span was noted. RESULTS: The tumors were enlarged in Met-containing group and shrank in Met-deprived group markedly after the treatment. The DNA index (DI) of tumor cells and the body weight (BW) of rats had no significant change in the two groups, however, the ratio of tumor cells'S phase was increased. The ratio of G2M phase went up in Met-containing group, but down in Met-deprived group. In the other two groups that 5-FU was added, the BW of rats, and the diameter of tumors, the DI of tumor cells, the S and G2M phase ratio of tumor cells were all decreased, particularly in Met-deprived plus 5-FU group. Pathological examination revealed that the necrotic foci of the tumor tissue increased after Met-deprived TPN treatment, and the nucleoli of tumor cells enlarged. In MetTPN+5-FU group, severe nuclear damage was also found by karyopyknosis and karyorrhexis, meanwhile there was slight degeneration in some liver and kidney cells. The serum free Met and Cysteine decreased markedly (P【0.001), while other amino acids, such as serum free serine and glutamine increased significantly (P【0.005). All the rats died of multiple organ failure caused by cancer metastasis. The average survival time was 18.6 days in Met-containing TPN group, 31 days in Met-deprived TPN group, 27.5 days in Met-containing TPN+5-FU group, and 43 days in Met-deprived TPN+5-FU group (P【0.05). CONCLUSION: Met-deprived TPN causes methionine starvation of tumor cells, and can enhance the anti-tumor effect of 5-FU and prolong the life span of gastric cancer bearing rats.

Activity of boanmycin against colorectal cancer

INTRODUCTIONBoanmycin (Bleomycin A6, BAM ), a newantitumor antibiotic, was isolated from manycomponents of bleomycin (BLM) produced bystreptomyces pingyangensis which were obtainedfrom a soil sample collected in Pingyang County,Zhejiang Province, China. Boanmycin has a similarchemical structure to that of BLM, but the terminalamine moiety is different[ 1].

Re:5-Fluorouracil-induced sperm shape abnormalities in rats

Dear Sir,5-Fluorouracil (5-FU) has been widely used clinically in the treatment for malignancies. Even though it has long been proved to be a gonadotoxic and mutagenic agent, its effect on sperm morphology has not been well

Role of Akt signaling in resistance to DNA-targeted therapy

The Akt signal transduction pathway controls most hallmarks of cancer. Activation of the Akt cascade promotes a malignant phenotype and is also widely implicated in drug resistance. Therefore, the modulation of Akt activity is regarded as an attractive strategy to enhance the efficacy of cancer therapy and irradiation. This pathway consists of phosphatidylinositol 3 kinase(PI3K), mammalian target of rapamycin, and the transforming serine-threonine kinase Akt protein isoforms, also known as protein kinase B. DNA-targeted agents, such as platinum agents, taxanes, and antimetabolites, as well as radiation have had a significant impact on cancer treatment by affecting DNA replication, which is aberrantly activated in malignancies. However, the caveat is that they may also trigger the activation of repairing mechanisms, such as upstream and downstream cascade of Akt survival pathway. Thus, each target can theoretically be inhibited in view of improving the potency of conventional treatment. Akt inhibitors, e.g., MK-2206 and perifosine, or PI3K modulators, e.g., LY294002 and Wortmannin, have shown some promising results in favor of sensitizing the cancer cells to the therapy in vitro and in vivo, which have provided the rationale for incorporation of these novel agents into multimodality treatment of different malignancies. Nevertheless, despite the acceptable safety profile of some of these agents in the clinical studies, with regard to the efficacy, the results are still too preliminary. Hence, we need to wait for the upcoming data from the ongoing trials before utilizing them into the standard care of cancer patients.

The Effect of calmodulin antagonist berbaminederivative-EBB on hepatoma in vitro and in vivo

OBJECTIVE: To evaluate the anti-hepatoma effect of Calmodulin antagonist 0 - 4-ethoxyl-butyl-Berbamine (EBB), one of the berbamine derivatives. METHODS: Monotetrazolium (MTT) method was used to analyze the effect of EBB on the proliferation and growth inhibition effect. Of a hepatoma cell line in vitro. A mouse hepatoma model was induced by injection of hepatoma cells (H22) in the abdominal cavity. The effect of EBB on survival at different concentrations as well as in combination with 5-FU were investigated in vivo. Flow cytometry analysis, dot blot hybridization, western blot, immunochemistry, enzyme-linked lectin assay (ELISA), trifluoperazine (TFP) and electron microscopic observation were used to study the effect of EBB on cell cycle process, P53 mRNA and protein levels, calmodulin content and ultrastractural changes of hepatoma cells. RESULTS: EBB exerts a very strong inhibitory effect on human hepatoma cell line 7402 and mouse hepatoma cell line H22 in vitro. The IC(50) value of EBB for the two cell lines are 3.312 microg/ml and 1.167 microg/ml, respectively. The sensitivity of H22 cells to 5-FU can be markedly enhanced: The IC(50) dosage of 5-Fu can be decreased from 0.75 microg/ml down to 0.15 microg/ml, when jointly administered with nontoxic dosages of EBB (IC(10)). In vivo, EBB can prolong the lifespan of mice with ascites H22 to more than three months. 64% of mice survived, while all animals in the control group died by the 18th day. When EBB (5 mg x kg(-1) x d(-1)) is jointly used with 5-FU (25 mg x ml(-1) x d(-1)), 73% of mice with ascites H22 survived, much higher than 27% in the 5-FU treated group. EBB can enhance the anti-hepatoma ability of 5-Fu treatment. EBB mechanism against hepatoma: P53 expression in the EBB treated group is substantially higher than that in the control group. EBB increased the translation of P53. As a calmodulin antagonist, EBB decreases amount of the CaM in hepatoma cells and blocked the hepatoma cell proliferation cycle at the G(2)M phase. Before the G(0)/G(1) phase, a diploid peak and apoptic cells in the treated groups were observed. CONCLUSIONS: The CaM antagonist, EBB, has a strong anti-hepatoma effect and enhances the effect of 5-FU, induces hepatoma cell to apoptosis, promotes the P53 protein expression and decreases the amount of CaM in the cytoplasm. All these results demonstrate that EBB is a new and potentially useful drug against hepatoma and should be researched further.

Increased sensitivity of colorectal cancer cell lines with microsatellite instability to 5-fluorouracil in vitro

OBJECTIVE: To study the relationship between sensitivity to 5-FU and the status of a panel of microsatellite loci in three human colon cancer cell lines. METHODS: Cell viability in several concentrations of 5-FU was assessed by the MTT test. Expression of hMSH2 and hMLH1 in LoVo, SW480 and SW1116 cells were analyzed by immunocytochemical staining.Ten mononucleotide and dinucleotide microsatellite loci were analyzed by the PCR-SSLP-silver staining method. RESULTS: By MTT assay, it showed that LoVo cells were more sensitive than SW480 and SW1116 cells (0.8 micromol/L,2.2 micromol/L and 1.9 micromol/L, respectively, P