Vesicular Stomatitis Virus G Glycoprotein and ATRA Enhanced Bystander Killing of Chemoresistant Leukemic Cells by Herpes Simplex Virus Thymidine Kinase/Ganciclovir

Refractoriness of acute myeloid leukemia (AML) cells to chemotherapeutics represents a major clinical barrier. Suicide gene therapy for cancer has been attractive but with limited clinical efficacy. In this study, we investigated the potential application of herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) based system to inhibit chemoresistant AML cells. We first generated Ara-C resistant K562 cells and doxorubicin-resistant THP-1 cells. We found that the HSV-TK/GCV anticancer system suppressed drug resistant leukemic cells in culture. Chemoresistant AML cell lines displayed similar sensitivity to HSV-TK/GCV. Moreover, HSV-TK/GCV killing of leukemic cells was augmented to a mild but significant extent by all-trans retinoic acid (ATRA) with concomitant upregulation of Connexin 43, a major component of gap junctions. Interestingly, HSV-TK/GCV killing was enhanced by expression of vesicular stomatitis virus G glycoprotein (VSV-G), a fusogenic membrane protein, which also increased leukemic cell fusion. Co-culture resistant cells expressing HSV-TK and cells stably transduced with VSV-G showed that expression of VSV-G could promote the bystander killing effect of HSV-TK/GCV. Furthermore, combination of HSV-TK/GCV with VSV-G plus ATRA produced more pronounced antileukemia effect. These results suggest that the HSV-TK/GCV system in combination with fusogenic membrane proteins and/or ATRA could provide a strategy to mitigate the chemoresistance of AML.

Construction and identification of prostate-specific double gene expression vector pIRES-PSMAe/p-TKCx43 / 中华泌尿外科杂志

Objective To construct the prostate-specific double gene expression vector pIRESPSMAe/p-TK-Cx43 and establish the foundation for experimental prostate cancer gene therapy research. Methods Cx43 gene was amplified and cloned into pMD19-T Simple vector. HSV-TK gene was then synthesized and cloned into multiple clone site (MCS) A of the eukaryotie vector plRES. The new plasmid was named plRES-TK: PSMAe/p was obtained and cloned into plRES-TK by replacing CMV promoter. The new plasmid was named plRES-PSMAe/p-TK; Fourth, Cx43 gene was cloned into the MCS B of pIRES-PSMAe/p-TK and the new plasmid was named pIRES-PSMAe/p-TK-Cx43.This plasmid was identified by double digestion with Sal Ⅰ/Not Ⅰ and sequenced; Finally, LNCaP cells were transfected by the plasmid plRES-PSMAe/p-TK-Cx43 and the mRNAs expression of HSV-TK gene and Cx43 gene was tested by RT-PCR. Results The plasmids synthesized in this experiment were double digested respectively and the specific bands of the inserted genes were confirmed by RTPCR. plRES-PSMAe/p-TK-Cx43 was in line with the expected design by DNA sequencing. The mRNAs of TK gene and Cx43 gene were expressed and successfully confirmed by RT-PCR after LNCaP cells transfected with pIRES-PSMAe/p-TK-Cx43. Conclusion Double gene expression vector pIRES-PSMAe/p-TK-Cx43 containing HSV-TK gene and Cx43 gene is constructed successfully.

Adenovirus vector mediated HSV-tk gene killing action on Lewis lung cancer cells / 吉林大学学报(医学版)

Objective To study the killing action of adenovirus vector carrying HSV-tk(AdCMVtk) on Lewis cells.Methods The recombinant adenovirus carrying HSV-tk was constructed by homologous recombination techniques.The adenovirus transfected efficiency to Lewis cells was measured,the cells were transfected by adenovirus vector with LacZ gene,then stained with X-gal.The effect of AdCMVtk/GCV system on survival rate of Lewis cells was observed.Results The adenovirus transfected efficiency to Lewis cells was increased with the increasing of multiplicity of infection(MOI).100% transfected efficiency needed MOI 500.AdCMVtk/GCV system could kill Lewis cells.When the amount of adenovirus or the concentration of GCV was increased,the cell survival rate was decreased,but AdCMVtk or GCV alone could not kill Lewis cells.The killing action existed bystander effect,74% Lewis cells were died with only 20% Lewis cells transfected AdCMVtk.Conclusion AdCMVtk/GCV system is effective and safe on killing tumor cells.

Microsphere Preparation of The Recombinant Adeno-Associated Virus as A Vector for Gene Therapy of Liver Cancer / 中国普外基础与临床杂志

Objective To evaluate the suitability of the biodegradable microsphere encapsulation of adenovirus as a targeting vector for gene therapy of hepatocellular carcinoma. Methods Encapsulate the recombinant adenovirus in PLG poly (lactic/glycolic) copolymer by the solution evaporation method, the release test and the bioactivity of viruses incorporated in vitro were studied. Results More than 19.3% of adenovirus was encapsulated in PLG microspheres. The release test shows that the adenovirus was released for more than 200 h, 50% were shed within the first 100 h, and their activity was retained. Conclusion Recombinant adenovirus can be formulated in a polymer preparation of PLG with retention of bioactivity. It may be a valuable vector for the gene therapy of liver cancer.

Construction and identification of the recombinant eukaryotic expression plasmid pHsp70-hsv-tk / 医学研究生学报

Objective: To construct the recombinant eukaryotic expression plasmid pHsp70-hsv-tk(pHT)for further target gene therapy research.Methods: The oligomers of primers were synthesized based on the reported sequences of hsv-tk and with the pHSV-106 plasmid as the template.Then the hsv-tk gene fragment was amplified and inserted into the pD3SX vector.E.coli DH5? was transformed with the recombinant plasmids and the bacterial colonies containing the recombinant plasmids were identified by the PCR cloning method,and the recombinant plasmids were extracted and purified.Results: The recombinant eukaryotic expression plasmid pHT was obtained.The target gene obtained by PCR amplification had the same molecular size as predicted.The recombined pD3SX plasmid contained correct recombinant hsv-tk sequences.Conclusion: The plasmid pHT was successfully constructed,which can be used for further target gene therapy research.

A Study of the Bystander Effect and Its Enhancement in HSV-TK Gene Therapy Using a Murine Neuroblastoma Model

PURPOSE: Selective introduction of genes conferring chemosensitivity into proliferating tumor cells may be used to treat cancer. We first investigated the bystander effect of retrovirus-mediated gene transfer of herpes simplex virus thymidine kinase(HSV-TK) gene to murine neuroblstoma cell line(neuro-2a) in vitro and in vivo. Second, we examined the mechanism and its enhancement of the bystander effect in murine neuroblastoma. METHODS: To investigate the bystander effect, we studied tumor growth and survival time after HSV-TK/ganciclovir(GCV) treatment in a syngenic A/J mouse neuroblastoma model by mixing various ratios of HSV-TK-expressing neuro-2a cells with wild type neuro-2a cells followed by GCV treatment. To investigate the mechanism of the bystander effect in murine neuroblastoma, immunohistochemistry using connexin 43, CD4 and CD8-specific monoclonal antibodies was analyzed. We studied whether IL-2-secreting neuro-2a cells(neuro-2a/IL-2) would potentiate the bystander effect. RESULTS: A strong bystander effect was observed in vitro and in vivo. The bystander effect in murine neuroblastoma was dependent on the immune response rather than connexin-mediated gap junction. Neuro-2a/IL-2 treatment enhanced the bystander effect in the HSV-TK/GCV system in murine neuroblastoma model. CONCLUSION: We conclude that the bystander effect in murine neuroblastoma depends on immune response and is enhanced by neuro-2a/IL-2.

Bystander Effect of HSV-TK/GCV Gene Therapy in Murine Neuroblastoma

PURPOSE: To demonstrate the bystander effect in murine neuroblastoma model which transduced with HSV-TK gene in vitro and in vivo. METHODS: The LNC/TK vector was transfered in vitro into the neuro-2a cells, murine neuroblastoma cell line. Variable mixed populations of neuro-2a cells consisting of HSV-TK+ or HSV-TK- were plated into culture plates and treated with GCV for another 4 days. Surviving cells were counted and cell viability was determinated. For investigating the in vivo bystander effect, variable mixed populations of neuro-2a cells consisting of HSV-TK+ and HSV-TK- were inoculated into A/J mice. The tumor size was measured following injection of GCV for 7 days. RESULTS: The survival rate of the 100% neuro-2a/TK group was 90%, 25%, 5% and 0%, of 50% neuro-2a/TK group was 92%, 30%, 10% and 0%, and of the 10% neuro-2a/TK group was 95%, 40%, 15% and 5%. But, the survival rate of 0% neuro-2a/TK group was 120%, 150%, 180% and 220% on days 1, 2, 3, and 4 respectively. In the 100% and 50% neuro-2a/TK groups, tumor had disappeared following administration of GCV and in 10% neuro-2a/TK group, tumor size was not increased during GCV treatment. In 0% neuro-2a/TK group, tumor size increased during administration of GCV and all mice died after 6 weeks. CONCLUSIONS: We demonstrated the bystander effect in a murine neuroblastoma model which transduced with HSV-TK gene in vitro and in vivo. These results suggest that HSV-TK/GCV gene therapy may be useful for treatment of neuroblastoma.

Killing Effects of Different Prodrugs Combined With Suicide Gene HSV-tk on Hep-2 in Vitro / 中国医师杂志

Objective To investigate and compare the killing effects of different prodrugs combined with suicide gene HSV-tk on laryngocacinoma cell, Hep-2 in vitro. Methods Retroviral expressing vector pL(tk)SN was constructed by recombinant DNA technology. Hep-2 cells were infected by the recombinant retrovirus. The positive cloning was obtained after G418 selection and were termed Hep/tk. The integration and expression of tk gene in Hep-2 cells were identified by RT-PCR and Southern blot. The growth state and prodrugs killing effect of tk gene modified cells were used to investigate the expression of tk gene and antitumour effect on Hep-2 cells. Results RT-PCR and Southern blot analysis confirmed the integration and expression of tk gene in Hep-2 cells. There was no significant difference in cell proliferation between the Hep/tk and Hep-2. After the treatment of GCV,the Hep/tk showed high sensitivity to GCV and bystander effects were observed siginificantly in vitro. However the efficiency of another two prodrugs ACV and BVdU was lower than that of GCV. Both tk-positive and tk-negative Hep-2 cells were relatively insensitive to ACV and BVdU.Treatment of tk gene modified cells mixed with different proportion parental cells shoewd obviously bystander effects.Conclusions The laryngocarcinoma cells Hep-2 have sensitive to HSV-tk/GCV system and have significant bystander effects, which might have therapeutic potential value for laryngocarcinoma.

The selective killing effect of adenoviral mediated HSV-tk/GCV suicide gene system controlled by hTERT promoter on bladder cancer cells / 中华泌尿外科杂志

Objective To investigate the selective killing effect of adenoviral mediated herpes simplex virus-thymidine kinase/ganciclovir (HSV-tk/GCV) suicide gene system controlled by human telomerase reverse transcriptase (hTERT) promoter on bladder cancer cells in vitro. Methods Bladder cancer cell line 253J and human fibroblast cell line MRC-5 were transfected by the recombinant adenovirus of different multiplicities of infection (MOI),and the infection rate was measured by observing the expression of enhanced green fluorescent protein (EGFP) under the fluorescent microscopy.Ad-hTERT-HSV/tk and Ad-CMV-HSV/tk were transduced into 253J and MRC-5,followed by GCV treatment. The relative survival rate of cells in presence of prodrug GCV was measured with MTT method. Results Recombinant adenovirus Ad-hTERT-EGFP could selectively infect 253J cells,with the infection rate associated with the increasing MOI of recombinant adenovirus (P

Herpes Simplex virus thymidine kinase gene therapy delivered by retroviral or adenoviral vector in mouse model of lewis lung carcinoma / 결핵

BACKGROUND: The antitumor effects of herpes simplex virus thymidine kinase(HSV-tk) and ganciclovir(GCV) strategies for cancer gene therapy have a the following advantages:1) a direct cytotoxicity to HSV-tk modified cancer cells by GCV 2) a cell death by the local transfer of toxic metabolites from the HSV-tk modified cells to nearby unmodified tumor cells(bystander effect), and 3) in vivo bystander effect such as antitumor-immunity. Retroviral and adenoviral sequences can silence transgene expression in cells and mice. In this study, we investigated the above described advantages of HXV-tk/GCV strategy in Lewis lung cell and mouse lung cancer model using retroviral vector and adenoviral vector. Also, we observed whether the expression of a silenced gene can be reactivated by treating cell with butyrate. METHODS: Retrovirus-HSV-tk and adenovirus-HSV-tk vectors were used for the transduction of Lewis lung carcinoma(LLC) cells. The change of HSV-tk expression by butyrate was measured by Western blot.The antitumor activities containing bystander effect were observed in vivo(by MTT assay) and in vivo tumor models of various combinations of LLC and LLC-tk. RESULTS: 1. Butyrate induced the enhancement of HSV-tk expression from adenovirally transduced cells but not from retrovirally transduced cells. 2. Both retrovirus-HSV-tk and adenovirus-HSV-tk vectors with GCV treatment were effective for killing of tumor cell in vitro and suppression of LLC tumorigenicity. Bystander effect was responsible for killing of mixture of LLC-tk and LLC in vitro and in vivo-tumorigenicity model. CONCLUSION: Butyrate could augment adenoviral vector seems to be an effective approach for lung cancer therapy.