Inhibitory effects of cytosine deaminase gene-transfected bone marrow mesenchymal stem cells on glioma cell proliferation

Bone marrow mesenchymal stem cells were isolated from C57BL mice, transfected with the cytosine deaminase （CD） gene using a lentivirus vector and co-cultured with C6 glioma cells to verify anti-tumor effects of bone marrow mesenchymal stem cells carrying CD genes. C57MSC-CD/eGFP cells converted 5-fluorocytosine to 5-fluorouracil and exhibited significant inhibition of proliferation and apoptosis in C6 glioma cells. C57MSC-CD/eGFP cells were then implanted into rat models of brain C6 glioma. Rats were also intraperitoneally injected with 5-fluorocytosine after 7 days. MSC-CD/eGFP cells were irregularly distributed at the margin of the glioma, as well as encased and reduced the volume of the glioma. CD-transfected bone marrow mesenchymal stem cells inhibit the in vivo growth and in vitro proliferation of glioma.

ENHANCED ANTITUMOR EFFECTS OF SUICIDE GENETHERAPY BY SIMULTANEOUS TRANSFER OF GM CSF GENE IN LEUKEMIABEARING MICE

In the present report, antitumor effect of combined transfer of suicide gene and cytokine gene was studied. Adenovirus engineered to express E. Coli. Cytosine deaminase (AdCD) and/or adenovirus engineered to express murine granulocytemacrophage colonystimulating factor (AdGMCSF) were used for the treatment of leukemiabearing mice. The mice were inoculated s.c. with FBL3 erythroleukemia cells and 3 days later received intratumoral injection of AdCD in the presence or absence of AdGMCSF followed by intraperitoneal 5fluorocytosine (5FC) treatment. The results demonstrated that mice received combined therapy of AdCD/5FC and AdGMCSF developed tumors most slowly and survived much longer when compared with mice treated with AdCD/5FC alone, AdGMCSF alone, AdlacZ/5FC or PBS. Combined transfer of CD gene and GMCSF gene achieved higher specific CTL activity than control therapies. Pathological examination illustrated that the tumor mass showed obvious necrosis and inflammatory cell infiltration in mice after combined therapy. The results demonstrated that combined transfer of suicide gene and cytokine gene could synergistically inhibit the growth of leukemia in mice and induce antitumor immunity of the host. The combination therapy might be a potential approach for cancer gene therapy.

Sensitization of prostate cancer cell lines to 5-fluorocytosine induced by adenoviral vector carrying a CD transcription unit

Objective To investigate the efficiency of the cytosine deaminase adenoviral/5-fluorocytosine system on prostate cancer cell lines.Methods We used cell culture, infectivity and sensitivity tests, to observe bystander effect by animal tests.Results Established prostate cancer cell lines are eventually infectible by adenoviral vector. The ratio of vector/cell at which infection occurs depends on the specific cell line. The peak of expression of the transferred cytosine deaminase gene occurred in cells at different time, but persisted beyond 11 days. These prostate cell lines are sensitized to 5-fluorocytosine by infection with adenoviral vector carrying the cytosine deaminase gene. Only 5% of the LNCap and 10% of the RM-1 cells were infected and produced 100% cell death. In the animal test, there was significant inhibition of tumor growth at a ratio of 400 vector particles/cell with the systematic treatment of 5-fluorocytosine.Conclusions Adenoviral vector carrying a cytosine deaminase transcription unit can sensitize prostate cancer cell lines to 5-fluorocytosine. The system can significantly inhibit the growth of prostatic tumors in mice.

Therapeutic effect of AdCMVCD/5-FC system and metabolism of 5-FC in the treatment of human tongue squamous cell carcinoma

To investigate the therapeutic effect and metabolism of 5 fluorocytosine (5 FC ) in human tongue squamous carcinoma cells after treatment with adenovirus medi ated cytosine deaminase (AdCMVCD)/5 FC system Methods Human tongue squamous carcinoma cells (Tca8113 cell line) and its xenografts in BALB/c nude mice were treated with AdCMVCD/5 FC system The killing effect in vitro and bystander effect were detected by microculture tetrazolium (MTT) assay Tumor inhibition effect and histopathological changes were observed in vivo High performance liquid chromatography (HPLC) was performed to determine the m etabolism of 5 FC in vitro and in vivo Results AdCMVCD/5 FC system had strong killing effect and bystander effect on Tca8113 c ells Both condition media and cell extracts showed two peaks identified as 5 FC and 5 fluorouracil (5 FU) by HPLC and a time dependent generation of 5 FU and concomitant time dependent decreases of 5 FC Compared to the control gr oups, mice treated with AdCMVCD/5 FC system demonstrated significant tumor regr ession ( P <0 001); the tumor doubling time prolonged and inhibition rate was 92 62% There were substantial tumor necrotic areas and infiltrative lymphocy tes around necrotic areas in the AdCMVCD/5 FC treated group under light microsc ope There was a significantly low concentration of 5 FC and high concentratio n of 5 FU in tumor tissue, but only 5 FC was found in blood Conclusion AdCMVCD/5 FC suicide gene system had significant in vitro and in vivo anti tum or effect on human tongue squamous cell carcinoma due to convert 5 FC into 5 F U