Improving adenoviral vectors and strategies for prostate cancer gene therapy

Gene therapy has been evaluated for the treatment of prostate cancer and includes the application of adenoviral vectors encoding a suicide gene or oncolytic adenoviruses that may be armed with a functional transgene. In parallel, versions of adenoviral vector expressing the p53 gene (Ad-p53) have been tested as treatments for head and neck squamous cell carcinoma and non-small cell lung cancer. Although Ad-p53 gene therapy has yielded some interesting results when applied to prostate cancer, it has not been widely explored, perhaps due to current limitations of the approach. To achieve better functionality, improvements in the gene transfer system and the therapeutic regimen may be required. We have developed adenoviral vectors whose transgene expression is controlled by a p53-responsive promoter, which creates a positive feedback mechanism when used to drive the expression of p53. Together with improvements that permit efficient transduction, this new approach was more effective than the use of traditional versions of Ad-p53 in killing prostate cancer cell lines and inhibiting tumor progression. Even so, gene therapy is not expected to replace traditional chemotherapy but should complement the standard of care. In fact, chemotherapy has been shown to assist in viral transduction and transgene expression. The cooperation between gene therapy and chemotherapy is expected to effectively kill tumor cells while permitting the use of reduced chemotherapy drug concentrations and, thus, lowering side effects. Therefore, the combination of gene therapy and chemotherapy may prove essential for the success of both approaches.

Construction of nasopharyngeal carcinoma CNE-2 cell lines expressing stable fusion suicide gene CD/UPRT. UL49 / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To construct nasopharyngeal carcinoma CNE-2 cell lines expressing stable fusion suicide gene CD/UPRT. UL49.@*METHOD@#The plasmids of pcDNA3.1 (-)E6. BARF1p. CD/UPRT. UL49 was transfected into CNE-2 cells through lipofectamine, and the transfected CNE-2 cells were selected by G418 and prodrugs for getting the cells expressing fusion CD/UPRT. UL49 gene. The protein produced by the suicide gene was tested by Western-blotting in CNE-2 cells.@*RESULT@#Suicide genes were expressed stably in CNE-2 cells.@*CONCLUSION@#We constructed nasopharyngeal carcinoma cell lines CNE-2 expressing stable suicide gene through lipofectamine.

Establishment of surfactant-associated protein A suicide gene system and analysis of its activity / 华中科技大学学报（医学）（英德文版）

Alveolar epithelial type II (AT II) cells are essential for lung development and remodeling, as they are precursors for type I cells and also produce other non-repair cells (fibroblasts). Progenitor cells are believed to possess capability of multi-potent transdifferentiation, which is closely related to the niche, suggesting the importance of establishment of a lung progenitor cell niche model. We hypothesized that pulmonary surfactant-associated protein A (SPA) suicide gene system would cause AT II cell to kill itself through apoptosis and leave its niche. In vitro, the recombinant adeno-associated virus vectors-SPA-thymidine kinase (rAAV-SPA-TK) system was established to get targeted apoptotic AT II cells. The apoptosis of AT II cells was detected by using MTT. The results showed that cloned SPA gene promoter had specific transcriptional activity in SPA high expression cells, and SPA high expression cells (H441) transfected with TK gene had higher sensitivity to ganciclovir (GCV) than SPA low expression cells (A549). In vivo, increased apoptosis of AT II cells induced by GCV in rAAV-SPA-TK system was observed by TUNEL. Finally, the successful packaging and application of rAAV-SPA-TK system provide experimental basis to get specific lung progenitor cell (AT II) niche in vitro and in vivo.

An overview of gene therapy in head and neck cancer.

Gene therapy is a new treatment modality in which new gene is introduced or existing gene is manipulated to cause cancer cell death or slow the growth of the tumor. In this review, we have discussed the different treatment approaches for cancer gene therapy; gene addition therapy, immunotherapy, gene therapy using oncolytic viruses, antisense ribonucleic acid (RNA) and RNA interference‑based gene therapy. Clinical trials to date in head and neck cancer have shown evidence of gene transduction and expression, mediation of apoptosis and clinical response including pathological complete responses. The objective of this article is to provide an overview of the current available gene therapies for head and neck cancer.

Growth and mutation of Escherichia coli with suicide gene circuit based on quorum sensing / 生物工程学报

Constructing robust gene circuits is a fundamental work for synthetic biology. Bacteria with suicide gene circuit based on quorum-sensing will kill themselves in a controllable pattern upon certain cell density. In the media of different IPTG inducer concentration, we observed the growth and suicidal behavior of the Escherichia coli. Top10F' with such gene circuit, screened the mutants and determined their mutated loci. The results show that, with higher IPTG concentration, the more wild type bacteria were killed; as well the mutants emerged earlier and spread over the population more quickly. The sequence of plasmids in those mutants revealed that a transposon inserted into the luxR gene and therefore disrupted Quorum-Sensing of these individuals. Furthermore, the insertion sequence of the plasmid can solely result in the mutants escaping from suicide.

Role of wild type p53 and double suicide genes in interventional therapy of liver cancer in rabbits / Papel do p53 selvagem e do duplo genes suicidas na terapia intervencionista do câncer de fígado em coelhos

PURPOSE: To investigate the feasibility of interventional lipiodol embolism and multigene therapy in combination with focal chemotherapy in the treatment of VX2 liver cancer in rabbits. METHODS: Forty five rabbits with cancer larger than 2cm in diameter were randomly divided into five groups (n=9 per group). In Group 1, animals were treated with 0.9% sodium chloride. In Group 2, animals received lipiodol embolism. In Group 3, animals received lipiodol embolism and p53 gene therapy. In Group 4, animals received lipiodol embolism and TK/CD gene therapy. In Group 5, animals received lipiodol embolism and p53 and TK/CD gene therapy. Ultrasonography and CT were performed before and at ten days after interventional therapy. RESULTS: The VX2 model of liver cancer was successfully established in rabbits and interventional therapy smoothly performed. At ten days after interventional therapy, significant difference in the tumor volume was noted among five groups (p<0.05) and different treatments could inhibit the cancer growth. The inhibition of cancer growth was the most evident in the Group 5. Factorial analysis revealed gene therapy with p53 or TK/CD and lipiodol embolism independently exert significantly inhibitory effect on cancer growth. In addition, the suppression on tumor growth rate was the most obvious in the Group 5. CONCLUSIONS: Combination of gene therapy with lipiodol embolism can effectively inhibit the cancer growth and prolong the survival time. These findings demonstrate the effectiveness of multigene therapy in combination with lipiodol embolism in the treatment of liver cancer.

OBJETIVO: Investigar a possibilidade de terapia multigênica e intervenção por embolização com lipiodol em combinação com quimioterapia focal no tratamento de câncer de fígado VX2 em coelhos. MÉTODOS: Quarenta e cinco coelhos com câncer maior do que 2cm de diâmetro foram distribuídos, aleatoriamente, em cinco grupos (n=9 por grupo). Grupo 1: animais foram tratados com cloreto de sódio 0,9% e no grupo 2 os animais receberam embolização com lipidol. Grupo 3: animais receberam embolização com lipiodol e terapia do gene p53 e grupo 4 animais receberam embolização com lipiodol e terapia do gene TK/CD. Grupo 5: animais receberam embolização com lipiodol e terapia do gene p53 e do gene TK/CD. Ultrassonografia e tomografia computadorizada foram realizadas antes e dez dias após a intervenção terapêutica. RESULTADOS: O modelo VX2 de câncer de fígado foi estabelecido com sucesso em coelhos e a terapia intervencionista foi bem executada. Dez dias após a intervenção terapêutica, uma diferença significativa no volume do tumor foi observada entre os cinco grupos (p<0,05) e diferentes tratamentos poderiam inibir o crescimento do câncer. A inibição do crescimento do cancer foi mais evidente no grupo 5. Análise fatorial revelou que a terapia com gene p53 ou TK/CD e embolia por lipiodol independentemente exerce um efeito inibidor significativo sobre o crescimento do câncer. Além disso, a supressão da taxa de crescimento do tumor foi mais evidente no Grupo 5. CONCLUSÕES: A combinação de terapia gênica com embolização com lipiodol pode inibir efetivamente o crescimento do câncer e prolongar o tempo de sobrevida. Estes resultados demonstram a eficácia da terapia multigênica em combinação com embolização com lipidol no tratamento de câncer hepático.

DNA damage caused by suicide gene therapy system under Tet-On regulation in breast cancer cells / 中南大学学报(医学版)

OBJECTIVE@#To determine the effect and molecular mechanism of DNA damage caused by suicide gene therapy system HSV-TK/GCV under Tet-On regulation in human breast cancer cell line MCF-7 infected by recombinant adeno-associated virus (rAAV).@*METHODS@#We used comet assay to detect the effect of HSV-TK/GCV suicide gene regulation system on MCF-7 DNA damage, and analyzed the expression change of relative DNA damage response active genes and proteins with RT-PCR and Western blot.@*RESULTS@#Compared with other control groups, the comet assay showed that MCF-7 cells with HSV-TK/GCV treatment had obvious comet tails, and the expression level of DNA damage response active genes and proteins changed obviously in the HSV-TK/GCV treatment group,such as ATM, p53 and p27,but CyclinE and CDK2 did not change.@*CONCLUSION@#DNA damage on MCF-7 cells is resulted from HSV-TK/GCV in suicide gene therapy system through a p53-dependent signal pathway, causing cell cycle arrest and cell death.

Gene and environment interaction in familial suicidal behavior: a single family with 4 committed suicides

Family history of suicide is among the strongest predictors of suicide risk. From the context of gene by environment interactions, this manuscript presents a case study of the "M" family, which experienced 4 committed suicides within a short time period. Over the course of 5 years, the father and 3 sons committed suicide. Suicidal ideations developed in several other members of the family. The family's suicide risk appears to have stemmed from both environmental and genetic factors, and likely from an interactive effect between both. Environmental factors included low level of education, opium dependency among male family members, unemployment, and poverty, and limited access to mental health services. Genotype analyses of A218C polymorphism among surviving family members revealed that all individuals were associated with the gene variation [genotypes CC and AC] in tryptophan hydroxylase. The genetic by environmental interaction influence is discussed

Mechanism of DADS in the bystander effect of HSV-tk/GCV suicide gene therapy system in lens epithelial cells / 中南大学学报(医学版)

OBJECTIVE@#To investigate the mechanism and effect of diallyl disulfide (DADS) on the bystander effect of herpes simplex virus kinase/ganciclovir (HSV-tk/GCV) suicide gene therapy system which was mediated by recombinant adeno-associated virus (rAAV) in lens epithelial cells.@*METHODS@#Immunohistochemistry method was used to determine the distribution of connexin 43 (Cx43) protein in cultured rabbit lens epithelial cells and rabbit lens epithelial cells transfected by HSV-tk suicide gene. Cx43 protein was measured and analyzed in cultured rabbit lens epithelial cells and rabbit lens epithelial cells transfected by HSV-tk suicide gene that was induced by various DADS. Cell survival was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method.@*RESULTS@#DADS increased the Cx43 protein expression in cultured rabbit lens epithelial cells and rabbit lens epithelial cells transfected by HSV-tk suicide gene, and especially in 50 μmol/L DADS. After combining with DADS, the bystander effect was significantly improved (P<0.05).@*CONCLUSION@#DADS can elevate the expression of Cx43 protein and enhance the bystander effect of HSV-tk/GCV suicide gene therapy system.

Advancement and prospects of tumor gene therapy / 癌症

Gene therapy is one of the most attractive fields in tumor therapy. In past decades, significant progress has been achieved. Various approaches, such as viral and non-viral vectors and physical methods, have been developed to make gene delivery safer and more efficient. Several therapeutic strategies have evolved, including gene-based (tumor suppressor genes, suicide genes, antiangiogenic genes, cytokine and oxidative stress-based genes) and RNA-based (antisense oligonucleotides and RNA interference) approaches. In addition, immune response-based strategies (dendritic cell- and T cell-based therapy) are also under investigation in tumor gene therapy. This review highlights the progress and recent developments in gene delivery systems, therapeutic strategies, and possible clinical directions for gene therapy.

Anti-tumor effect of suicide gene therapy using chimeric promoter plus radiotherapy on cancer cell lines / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the synergistic anti-tumor effect of radiotherapy and horseradish peroxidase/prodrug indole-3-acetic acid (HRP/IAA) gene therapy system using chimeric hTERT promoter responsive to ionizing radiation.</p><p><b>METHODS</b>The synthetic hTERT promoters containing four tandem-repeat copies of radio-inducible CArG elements, and the chimeric promoter containing cytomegalovirus (CMV) early promoter were both constructed. The activities of the chimeric promoters in cancer cell lines (HeLa, A549, and MHCC97) and normal cell line (MRC-5) were detected using luciferase reporter gene expression analysis after a (60)Co γ-irradiation treatment at a series of doses(a single dose of 0 to 10 Gy). The anti-tumor effect of combining irradiation with HRP/IAA gene-directed enzyme prodrug therapy system controlled by the chimeric promoter was tested by colony formation assay, cell counting and apoptosis analysis.</p><p><b>RESULTS</b>The chimeric promoters were ineffective in normal human cells, even after irradiation, but the expression of luciferase gene in tumor cells was significantly higher. The activity of the chimeric promoter in MRC-5 cells was 22.3%, 12.9% and 13.6% of that in HeLa, A549 and MHCC97 cells, respectively. After irradiation, the ratios were 11.7%, 8.7% and 8.8%, respectively. Furthermore, the chimeric promoters could successfully induce the expression of luciferase gene following different doses of radiation, with maximal inducible activity seen after 6 Gy irradiation. The chimeric promoter containing four tandem-repeat copies of radio-inducible CArG elements and CMV early promoter showed the highest activity with 6 Gy irradiation. The relative luciferase activities in HeLa, A549 and MHCC97 cells were 1.7 ± 0.2, 2.3 ± 0.2 and 2.3 ± 0.1, respectively. The chimeric promoter mediated suicide gene therapy system could increase radio-sensitivity in different cancer cells. Compared with the control system, it plus irradiation showed stronger cell proliferation inhibition, 67.3% vs. 26.1% in HeLa, 69.0% vs. 28.3% in A549, 64.6% vs. 20.8% in MHCC97 cells, and also higher apoptosis-inducing effect, 39.6% vs. 14.2% in HeLa, 33.0% vs. 12.4% in A549, and 33.2% vs. 14.2% in MHCC97 cells.</p><p><b>CONCLUSIONS</b>Chimeric promoter containing hTERT promoter, CArG elements and CMV promoter preserve the tumor-specificity in telomerase-positive tumor cells, and irradiation-responsive to low dose of radiation. The suicide gene therapy using this promoter plus radiotherapy show a strong anti-tumor effect in vitro. It is expected to have a good potential for future application in gene radiotherapy.</p>

Double suicide gene therapy with RNAi targeting to STAT3 inhibits the growth of colorectal carcinoma cells in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>The aim of this study was to construct a recombinant plasmid carrying fusion suicide gene CDglyTK and RNA interference eukaryotic expressing vector targeting to STAT3, and to investigate the effect of double suicide gene combined with RNAi targeting to STAT3 on HCT116 and HUVEC cells in vitro.</p><p><b>METHODS</b>The CD and TK were cloned by polymerase chain reaction (PCR), and fusion gene CDglyTK was inserted into plasmid pEGFP after DNA sequence analysis, enzyme digestion and ligation. The recombinant plasmid was analyzed by PCR amplification and electrophoresis and enzyme digestion. DNA sequences containing small hairpin structure targeting to STAT3 were synthesized and inserted into the vector. The CDglyTK gene expressions in HCT116 and HUVEC cells were examined by reverse transcription-polymerase chain reaction (RT-PCR) after transfection of HCT116 and HUVEC cells. The inhibitory effect of RNA interference vector targeting to STAT3 was analyzed by RT-PCR and Western blot. The effects of 5-FC and GCV on HCT116 and HUVEC cells transfected with the recombinant plasmids were detected by MTT staining.</p><p><b>RESULTS</b>The results of restriction enzyme digestion and PCR amplification and electrophoresis showed that the recombinant pEGFP/CDglyTK was constructed correctly. The mRNA expression of gene CDglyTK was detected in HCT116 and HUVEC cells which transfected with the recombinant plasmid. The results of RT-PCR and Western blot showed that the RNA interference expression vector targeting to STAT3 effectively inhibited the expression of STAT3 in HCT116 cells. The results of MTT test showed that the inhibition ratio of group pEGFP/CDglyTK was (63.72 ± 0.64)%, significantly higher than that of control group (P < 0.05). The inhibition rate of group pEGFP/STAT3 siRNA was (47.02 ± 0.39)%, which was lower than that of group pEGFP/CDglyTK (P < 0.05), and higher than that of control group (P < 0.05). The inhibition rate of group pEGFP/CdglyTK + pEGFP/STAT3 siRNA was (85.10 ± 0.17)%, significantly higher than those of groups pEGFP/CDglyTK and group pEGFP/STAT3 siRNA (P < 0.05). Meanwhile, in HUVEC cells, the inhibition rate of group pEGFP/CDglyTK was (70.24 ± 0.33)%, significantly higher than that of the control group (P < 0.05). The inhibition rate of group pEGFP/STAT3 siRNA was (46.32 ± 0.15)%, significantly lower than that of group pEGFP/CdglyTK (P < 0.05), and higher than that of the control group (P < 0.05). The inhibition rate of group pEGFP/CdglyTK+pEGFP/STAT3 siRNA was (87.10 ± 0.24)%, significantly higher than those of groups pEGFP/CDglyTK and pEGFP/STAT3 siRNA(P < 0.05).</p><p><b>CONCLUSION</b>The recombinant plasmids pEGFP-CDglyTK and pEGFP/STAT3 siRNA have inhibitory effect on HCT116 and HUVEC cells. The killing effects of double suicide gene combined with RNAi targeting to STAT3 are much better than those of single gene therapy.</p>

The construction of IGF-II P4 promoter-driven tk expression vector / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the selective killing effect of herpes simplex virus-thymidine kinase/ganciclovir (HSV-tk/GCV) suicide gene system controlled by human IGF-II P4 promoter on HCC cells in vitro.</p><p><b>METHODS</b>Recombinant shuttle plasmid vectors driven by IGF-II P4 promoter and driven by CMV promoter were constructed by techniques of gene recombination. The recombinant shuttle plasmids were then transfected into HepG2 and HeLa cells by techniques of lipidosome transfection. EGFP expression was detected by fluoroscopy. Tk and EGFP mRNA expression were detected by RT-PCR. The selective killing effect after GCV application was determined with MTT method. Statistical analysis was performed with ANOVA analysis.</p><p><b>RESULTS</b>Identification of pDC316-tkEGFP-P4 by enzyme digestion and sequencing analysis showed that the construction of the recombinant shuttle plasmid was correct. It was found that green fluorescence protein could only be seen in HepG2 cells, not in HeLa cells. The results of RT-PCR showed only two bands could be seen in the samples of pDC316-tkEGFP-P4 transfected HepG2 cells. The growth of HepG2 cells transfected with pDC316-tkEGFP-CMV and pDC316-tkEGFP-P4 were inhibited remarkably, the growth inhibition rates were 6.95% +/- 0.67%, 24.99% +/- 1.53%, 49.68% +/- 1.68%, 71.85% +/- 3.28% and 4.83% +/- 0.35% vs 17.34% +/- 1.15%, 30.17% +/- 1.30%, 40.39% +/- 0.82% (F = 24.055, P < 0.05), respectively. The growth of HeLa cells transfected with pDC316-tkEGFP-CMV were also inhibited, the growth inhibition rates were 6.36% +/- 0.83%, 23.95% +/- 1.72%, 45.13% +/- 1.64% and 69.38% +/- 3.17%, respectively. The growth of HeLa cells transfected with pDC316-tkEGFP-P4 was not inhibited. The growth inhibition rates were 0.91 +/- 0.04, 1.18 +/- 1.32, 1.19 +/- 0.10 and 1.32 +/- 0.05 (F = 26.469, P < 0.01) , respectively.</p><p><b>CONCLUSION</b>The shuttle plasmid vector carrying the tkEGFP fusion protein gene driven by IGF-II P4 promoter has been constructed successfully and its specific expression in HepG2 cells provided the basis for targeted gene therapy for HCC.</p>

Effect of suicide gene therapy in combination with immunotherapy on antitumour immune response & tumour regression in a xenograft mouse model for head & neck squamous cell carcinoma.

Background & objectives: Prodrug activation strategy as well as immunotherapy have been widely used for cancer gene therapy. In the present study, using a head and neck squamous cell carcinoma (HNSCC) xenograft nude mouse model, we have investigated whether the two therapies in combination could improve tumour cell kill. We also investigated induction of immune effector cells viz., NK (DX5+) and DC (CD11c+) in vivo, post-combination gene therapy. Methods: A retroviral vector producing cell line (PLTK47.1 VPC) carrying Herpes simplex virus thymidine kinase gene (HSVtk) was used for intratumoural injection into NT8e xenograft tumours followed by the prodrug ganciclovir (GCV). IL-2 plasmid DNA was injected intramuscularly. Immune cells were analyzed by flow-cytometry. Non parametric ANOVA was performed with Kruskal Wallis test. Results: IL-2 could induce proliferation of both NK cells (DX5+) and dendritic cells (CD11c+) in vivo. Apoptosis was higher in combination therapy group as compared to HSVtk/GCV alone or IL-2 alone and was mediated through caspase-3 dependent pathway. Significant reduction in tumour volume was seen in all 3 treatment arms as compared to controls. Interpretation & conclusions: Combination of suicide gene therapy and immunotherapy leads to successful tumour regression in a HNSCC xenograft mouse model. Immunotherapy could help in a systemic long lived anti-tumour immune response which would prove powerful for the treatment of metastatic cancers, and also for minimal residual disease. The results of this study may form the basis for Phase 1 clinical trials.

Study on the relationship between TK gene regulated by enhanced suicide gene vector and telomerase activity in nasopharyngeal carcinoma cells / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To explore the relationship between TK gene expression regulated by enhanced suicide gene vector and telomerase activity in nasopharyngeal carcinoma cells.@*METHOD@#The reformed reconstructed enhanced vector, pGL3-basic-EGFP-TK-hTRETp-CMV enhancer, and hTERT mono-promoter vector, pGL3-basic-EGFP-TK-hTRETp(as controls), were transfected into telomerase(+) nasopharyngeal carcinoma 5-8F cell lines, telomerase(+) human breast cancer MCF-7 cell lines and telomerase(-) normal vascular endothelium cell lines respectively. TK gene green fluorescent protein was observed by fluorescence microscope. The expression of TK gene mRNA was measured by the real-time fluorescent quantified PCR and the telomerase activity was determined by the method of TRAP argentation in malignant tumour cells pre- and post-transfected by enhanced vector. Meanwhile the relationship between TK and telomerase was analyzed.@*RESULT@#(1) A strong TK gene fluorescent show and TK mRNA expression were displayed after the enhanced suicide gene vector was transfected into nasopharyngeal carcinoma 5-8F cell lines and human breast cancer MCF-7 cell line, which were more stronger than those of mono-promoter group, pGL3-basic-EGFP-TK-hTRETp, and ECV cells transfected by enhanced suicide gene vector. Meanwhile,real-time fluorescent quantified PCR showed that the A value of enhanced vector group was higher than that of controls. (2) Telomerase activity after transfection of enhanced vector and GCV was lower than those before by the method of TRAP argentation in nasopharyngeal carcinoma cell lines,but no change in normal control cells after transfection of enhanced vector and GCV. (3) After adding GCV, the obvious inhibitory effect of tumour cells growth induced by pGL3-basic-EGFP-TK-hTRETp-CMV enhancer were observed in nasopharyngeal carcinoma 5-8F cell lines and human breast cancer MCF-7 cell line, which was higher than those of mono-promoter, pGL3-basic-EGFP-TK-hTRETp, pGL3-basic-EGFP3 and blank controls, but without inhibitory effect in ECV cells transfected by enhanced vector.@*CONCLUSION@#TK gene expression is regulated by hTERT promoter and CMV enhancer, and then the telomerase activity is reduced and the cancer cells are specifically killed. But it is unclear how the telomerase are down-regulated by TK gene.

Effect of ultrasound microbubble carrying herpes simplex virus thymidine kinase on hepatocellular carcinoma in mice / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To observe the effect of ultrasound microbubble carrying herpes simplex virus thymidine kinase hepatocellular carcinoma in mice.</p><p><b>METHODS</b>Kunming mice were inoculated subcutaneously with H22 tumor cells. 40 male mice bearing subcutaneous hepatoma were randomized into 4 groups: PBS (group A), HSV1-TK (group B), HSV1-TK (group C), and microbubble carrying HSV1-TK (group D) were injected into the tail vein every 3 days. Mice in group C and D were exposed to ultrasound. The expression of TK protein was detected by western blot. Ganciclovir (GCV) was intraperitoneally injected at a dose of 100 mg x kg (-1) x d(-1) in group B, group C and group D. The tumor size was measured every 2 days.</p><p><b>RESULTS</b>TK gene could be injected precisely into hepatocellular carcinoma with ultrasound monitor, and the expression of TK protein was found in all 4 groups. Expression in group D was higher than others (P < 0.05). The rate of tumor growth inhibition were 0 in group A, 3.90%+/-1.80% in group B, 22.70%+/-2.86% in group C, 41.25%+/-3.20% in group D (group B vs group C, P < 0.05; group D vs group C, P < 0.05; group D vs group B, P < 0.05).</p><p><b>CONCLUSION</b>Ultrasound microbubble not only improve target gene therapy, but also enhance transfection efficiency.</p>

Selective cytotoxic effect of lentivirus-mediated double suicide gene transfer on human gastric adneocarcinoma cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the selective cytotoxic effect of lentivirus-mediated double suicide gene (CD/TK) against human gastric carcinoma cells SGC-7901 in vitro.</p><p><b>METHODS</b>SGC-7901 cells were infected with FGW-KDRP-CD/TK vector and the infection efficiency was observed under a fluorescence microscope. The morphological changes of the infected cells were observed by Giemsa staining. Flow cytometry (FCM) was employed for cell cycle analysis, and the expression of CD/TK was detected by RT-PCR. The infected cells were then treated with the prodrugs ganciclovir (GCV) and/or 5-fluorocytosine (5-FC) at different concentrations, and the cytotoxic effects were evaluated using MTT method.</p><p><b>RESULTS</b>The infection efficiency of the lentiviral vector in SGC-7901 cells increased with the titer of the virus, which produced no significant effect on the cancer cell morphology in vitro or on the percentages of G0-G1, G2-M and S phase cells (P>0.05). RT-PCR demonstrated the expression of CD/TK gene in SGC-7901 cells infected by FGW-KDRP-CD/TK. The infected cells were highly sensitive to the prodrugs with a dose-dependent cytotoxic effect within a specific concentration range of the drugs, whereas the non-infected cells were not sensitive to the prodrugs. Combined use of the two prodrugs produced an obviously stronger inhibitory effect than either of the them (P<0.05). When combined, GCV and 5-FC at the concentration of 0.1+40, 1+80, 10+160, and 100+320 mg/L demonstrated a synergetic effect with a CDI<1.</p><p><b>CONCLUSION</b>Lentivirus-mediated CD/TK fusion gene system can selectively kill gastric cancer cells, and the two prodrugs show a synergistic cytotoxic effect.</p>

A double suicide gene system driven by KDR promoter selectively kills human colon adneocarcinoma SW480 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the selective killing effect of adenovirus (Ad)-mediated double suicide gene system driven by the KDR promoter (KDR-CDglyTK) on human colon adneocarcinoma SW480 cells.</p><p><b>METHODS</b>KDR-expressing SW480 cells and LS174T cells that did not express KDR were infected by KDR-CDglyTK, and the infection efficiency and the expression of CDglyTK in the cells were detected by RT-PCR. The infected cells were treated with the prodrugs 5-FC and GCV at different concentrations, and the cell-killing effects and bystander effects were evaluated by MTT method. DNA content and the cell cycle changes in SW480 cells were detected by flow cytometry.</p><p><b>RESULTS</b>The expression of green fluorescent protein (GFP) was observed in 95% of the infected SW480 and LS174T cells with a multiplicity of infection (MOI) of 100. RT- PCR demonstrated that the product of CD/TK gene existed in SW480 cells infected by Ad- KDR- CD/TK, but not in infected LS174 cells. The infected SW480 cells exhibited high sensitivity to the prodrugs, but the infected LS174T cells did not (P<0.01). Bystander effects of the double suicide gene system were observed in the coculture of the infected and non-infected SW480 cells. At the MOI of 100, treatment of the infected cells with the prodrugs resulted in increased cell percentage in G(0)-G(1) phase and decreased percentage in S phase and the prodrug-treated cells showed an apoptotic peak in flow cytometry.</p><p><b>CONCLUSION</b>CDglyTK fusion gene system driven by the KDR promoter selectively kills and induces the apoptosis of the KDR-CDglyTK SW480 cells.</p>

Effect of adenovirus-mediated CD/TK double suicide gene system on colorectal cancer growth and cytokines in the tumor microenvironment in mice / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of adenovirus-mediated CD/TK double suicide gene system on tumor growth and cytokine levels in the tumor microenvironment in mice bearing transplanted colorectal cancer.</p><p><b>METHODS</b>CT26 cells were implanted subcutaneously into 30 Balb/c mice, which were subsequently randomized into the control (n=15) and experimental group (n=15). After the tumor formation, CD/TK double suicide gene system was administered for tumor treatment, and the changes in the tumor volume, tumor inhibition rate, and levels of cytokines in the tumor microenvironment were investigated.</p><p><b>RESULTS</b>CD/TK double suicide gene system resulted in a significant inhibition of the tumor growth and significantly increased levels of such cytokines as IL-2, IL-10, TNFalpha and IFNgamma in the tumor microenvironment.</p><p><b>CONCLUSION</b>CD/TK double suicide gene system produces significant tumor inhibition effect and causes obvious cytokine changes in the tumor microenvironment in mice bearing transplanted colorectal cancer.</p>

Inhibitory effect of recombinant adenovirus containing CDglyTK double suicide gene driven by KDR promoter on human stomach adneocarcinoma SCG7901 cells in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the inhibitory effect of adenovirus-mediated fusion gene system driven by KDR promoter on the proliferation of human gastric adneocarcinoma SCG7901 cells and observe the bystander effect in vitro.</p><p><b>METHODS</b>SCG7901, ECV304 and HepG2 cells were infected with Ad-KDR-CDglyTK and Ad-CMV-CDglyTK at a multiplicity of infection (MOI) of 100, and the infection efficiency and the mRNA expressions of the transferred fusion gene were investigated. GCV and/or 5-FC at different concentrations were added into the culture medium of the infected cells to observe the targeted antitumor effect and bystander effect of CDglyTK suicide gene driven by KDR promoter.</p><p><b>RESULTS</b>With the MOI of the adenovirus of 100, the fluorescence emitted by green fluorescent protein (GFP) was observed in 95% of the infected SCG7901, ECV304 and HepG2 cells. All the cells infected by Ad-CMV-CDglyTK and SCG7901 and ECV304 cells infected by Ad-KDR-CDglyTK were highly sensitive to the prodrugs. In comparison, HepG2 cells infected with Ad-KDR-CDglyTK did not show much sensitivity to the two prodrugs. Following treatment with the prodrugs at the same concentration, the infected SCG7901 and ECV304 cells exhibited gradually lowered survival rates as the culture time was prolonged, whereas the transgenic HepG2 cells showed no such time-dependent changes. When the non-infected cells were cocultured with the transgenic cells, the bystander effect of CDglyTK gene was observed, which increased with the ratio of the transgenic cells. In these mixed cell culture systems, GCV and 5-FC showed obvious synergetic effect in suppressing the cell survival.</p><p><b>CONCLUSION</b>The CDglyTK fusion gene system driven by KDR promoter can inhibit the proliferation of SCG7901 and ECV304 cells with obvious bystander effect in vitro. The combination of the prodrugs produces obvious synergetic effect against the cell survival.</p>