• Journal of Korean Neurosurgical Society
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• v.29 no.4
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• pp.471-476
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• 2000

Objective : p16/INK4a, a kind of tumor suppressor genes, encodes a specific inhibitor of the cyclin D-dependent kinases CDK4 and CDK6. This prevents the association of CDK4 with cyclin D1, and subsequently inhibits phosphorylation of retinoblastoma tumor suppressor protein(pRb), thus preventing exit from the G1 phase. According to previous reports, over 50% of glioma tissue and 80% of glioma cell lines have been demonstrated inactivation of p16/INK4a gene. The purpose of this study was to determine whether recombinant adenovirus-p16 virus is a suitable candidate for gene replacement therapy in cases of glioma. Methods : Three human glioma cell lines(U251MG, U87MG and U373MG) that express mutant p16 protein were used. Replication-deficient adenovirus was utilized as an expression vector to transfer exogenous p16 cDNA into the cells ; control cells were infected with the Ad-${\beta}$-gal expressing ${\beta}$-galactosidase. To monitor gene transfer and the expression of exogenous genes, we used Western Blotting analysis. Flow cytometry studies of cellular DNA content were performed to determine the cell cycle phenotype of the glioma cells before and after treatment. Results : We showed here that restoration of p16/INK4a expression in p16 negative U87MG, U251MG and partially deleted U373MG by Ad-CMV-p16 induced growth suppression in vitro. Flow cytometric study revealed that Ad-CMV-p16 infected U87MG cells were arrested during the G0-G1 phase of the cell cycle. Expression of p16 transferred by Ad-CMV-p16 in glioma cells was highly efficient and maintained for more than seven days. Conclusions : Our results suggest that Ad-CMV-p16 gene therapy strategy is potentially useful and warrants further clinical investigation for the treatment of gliomas.

• Tuberculosis and Respiratory Diseases
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• v.51 no.2
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• pp.135-146
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• 2001

Background : One of the important mechanisms responsible for a tumor escaping the immune response is an absence of the tumor associated antigen (TAA) on the cancer cell surface. To overcome this, combination gene therapy using a herpes simplex thymidine kinase (HSTK) gene, prototype of drug sensitizing gene, was conducted to enhance T AA release by cell destruction, as well as the cytokine genes for immune cell attraction. Methods : We investigated whether or not transduction with the adenovirus-HSTK (Ad-HSTK) enhanced the sensitivity of Lewis lung carcinoma (LLC) to ganciclovir (GCV) and induced a bystander effect. A Tumor vaccine trial was performed using LLC with ad-HSTK$\pm$ad-GM-CSF$\pm$ad-IL-2 to determine if they exhibit some antitumor effect on established lung cancer xenografts. Results : LLC with ad-HSTK revealed a much higher sensitivity to ganciclovir (GCV). LLC transduced with ad-HSTK and/or ad-IL-2, ad-GM-CSF showed a lower in vivo tumorigenicity. In the treatment experiment, vaccination with LLC transduced with ad-HSTK, ad-IL-2, or ad-GM-CSF alone modestly suppressed the growth of an established tumor. Combined transduction with HSTK and GM-CSF induced stronger growth suppression of a established lung cancer, while HSTK and IL-2 combination transduction did not have any antitumor effect on individual transduction. Vaccination with LLC-HSTK-GM-CSF increased the infiltration of dendritic cells in the spleen. Conclusion : It was concluded that a tumor vaccine transduced with HSTK and GM-CSF induces strong antitumor immunity by activating the dendritic cells.

• BMB Reports
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• v.45 no.4
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• pp.207-212
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• 2012

Retroviruses have often been used for gene therapy because of their capacity for the long-term expression of transgenes via stable integration into the host genome. However, retroviral integration can also result in the transformation of normal cells into cancer cells, as demonstrated by the incidence of leukemia in a recent retroviral gene therapy trial in Europe. This unfortunate outcome has led to the rapid initiation of studies examining various biological and pathological aspects of retroviral integration. This review summarizes recent findings from these studies, including the global integration patterns of various types of retroviruses, viral and cellular determinants of integration, implications of integration for gene therapy and retrovirus-mediated infectious diseases, and strategies to shift integration to safe host genomic loci. A more comprehensive and mechanistic understanding of retroviral integration processes will eventually make it possible to generate safer retroviral vector platforms in the near future.

• BMB Reports
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• v.55 no.12
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• pp.615-620
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• 2022

The murine leukemia virus-based semi-retroviral replicating vectors (MuLV-based sRRV) had been developed to improve safety and transgene capacity for cancer gene therapy. However, despite the apparent advantages of the sRRV, improvements in the in vivo transduction efficiency are still required to deliver therapeutic genes efficiently for clinical use. In this study, we established a gibbon ape leukemia virus (GaLV) envelope-pseudotyped semi-replication-competent retrovirus vector system (spRRV) which is composed of two transcomplementing replication-defective retroviral vectors termed MuLV-Gag-Pol and GaLV-Env. We found that the spRRV shows considerable improvement in efficiencies of gene transfer and spreading in both human glioblastoma cells and pre-established human glioblastoma mouse model compared with an sRRV system. When treated with ganciclovir after intratumoral injection of each vector system into pre-established U-87 MG glioblastomas, the group of mice injected with spRRV expressing the herpes simplex virus type 1-thymidine kinase (HSV1-tk) gene showed a survival rate of 100% for more than 150 days, but all control groups of mice (HSV1-tk/PBS-treated and GFP/GCV-treated groups) died within 45 days after tumor injection. In conclusion, these findings sug-gest that intratumoral delivery of the HSV1-tk gene by the spRRV system is worthy of development in clinical trials for the treatment of malignant solid tumors.

• Tuberculosis and Respiratory Diseases
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• v.49 no.3
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• pp.298-309
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• 2000

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 HSV-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 cells 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 blol 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 adenovirus-mediated HSV -tk gene expression. Cancer gene therapy with HSV-tk suicide gene by retroviral and adenoviral vector seems to be an effective approach for lung cancer therapy.

• The Korean Journal of Nuclear Medicine
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• v.36 no.1
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• pp.74-79
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• 2002

In addition to the well-established use of positron emission tomography (PET) in clinical oncology, novel roles for PET are rapidly emerging in the field of gene therapy. Methods for controlled gene delivery to living bodies, made available through advances in molecular biology, are currently being employed in animals for research purposes and in humans to treat diseases such as cancer. Although gene therapy is still in its early developmental stage, it is perceived that many serious illnesses could be treated successfully by the use of therapeutic gene delivery. A major challenge for the widespread use of human gene therapy is to achieve a controlled and effective delivery of foreign genes to target cells and subsequently, adequate levels of expression. As such, the availability of noninvasive imaging methods to accurately assess the location, duration, and level of transgene expression is critical for optimizing gene therapy strategies. Current endeavors to achieve this goal include methods that utilize magnetic resonance imaging, optical imaging, and nuclear imaging techniques. As for PET, reporter systems that utilize genes encoding enzymes that accumulate positron labeled substrates and those transcribing surface receptors that bind specific positron labeled ligands have been successfully developed. More recent advances in this area include improved reporter gene constructs and radiotracers, introduction of potential strategies to monitor endogenous gene expression, and human pilot studies evaluating the distribution and safety of reporter PET tracers. The remarkably rapid progress occurring in gene imaging technology indicates its importance and wide range of application. As such, gene imaging is likely to become a major and exciting new area for future application of PET technology.

• BMB Reports
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• v.52 no.3
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• pp.181-189
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• 2019

Cancer remains a life-threatening disease and accounts for the major mortality rates worldwide. The practice of using biomarkers for early detection, staging, and customized therapy may increase cancer patients' survival. Deubiquitinating enzymes (DUBs) are a family of proteases that remove ubiquitin tags from proteins of interest undergoing proteasomal degradation. DUBs play several functional roles other than deubiquitination. One of the important roles of DUBs is regulation of tumor progression. Several reports have suggested that the DUB family members were highly-elevated in various cancer cells and tissues in different stages of cancer. These findings suggest that the DUBs could be used as drug targets in cancer therapeutics. In this review, we recapitulate the role of the DUB family members, including ubiquitin-specific protease, otubain protease, and important candidates from other family members. Our aim was to better understand the connection between DUB expression profiles and cancers to allow researchers to design inhibitors or gene therapies to improve diagnosis and prognosis of cancers.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9059-9064
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• 2014

MicroRNAs (miRNAs) are ubiquitously expressed small, non-coding RNAs that negatively regulate gene expression at a post transcriptional/translational level. They have emerging as playing crucial roles in cancer at all stages ranging from initiation to metastasis. As a tumor suppressor miRNA, aberrant expression of microRNA-29b (miR-29b) has been detected in various types of cancer, and its disturbance is related with tumor development and progression. In this review, we summarize the latest findings with regard to the tumor suppressor signatureof miR-29b and its regulatory mechanisms. Our review highlights the diverse relationships between miR-29b and its target genes in malignant tumors.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2445-2452
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• 2012

RNA interference has created a breakthrough in gene silencing technology and there is now much debate on the successful usage of RNAi based methods in treating a number of debilitating diseases. Cancer is often regarded as a result of mutations in genomic DNA resulting in faulty gene expression. The occurrence of cancer can also be influenced by epigenetic irregularities in the chromatin structure which leads to alterations and mutations in DNA resulting in cancer cell formation. A number of therapeutic approaches have been put forth to treat cancer. Anti cancer therapy often involves chemotherapy targeting all the cells in common, whereby both cancer cells as well as normal cells get affected. Hence RNAi technology has potential to be a better therapeutic agent as it is possible to deactivate molecular targets like specific mutant genes. This review highlights the successful use of RNAi inducers against different types of cancer, thereby paving the way for specific therapeutic medicines.

• Tuberculosis and Respiratory Diseases
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• v.63 no.1
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• pp.52-58
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• 2007

Background: Photodynamic therapy is a viable option for lung cancer treatment, and many studies have shown that it is capable of inducing cell death in lung cancer cells. However, the precise mechanism of this cell death has not been fully elucidated. To investigate the early changes in cancer cell transcription, we treated A549 cells with the photosensitizer DH-I-180-3 and then we illuminated the cells. Methods: We investigated the gene expression profiles of the the A549 lung cancer cell line, using a DEG kit, following photodynamic therapy and we evaluated the cell viability by performing flow cytometry. We identified the genes that were significantly changed following photodynamic therapy by performing DNA sequencing. Results: The FACS data showed that the cell death of the lung cancer cells was mainly caused by necrosis. We found nine genes that were significantly changed and we identified eight of these genes. We evaluated the expression of two genes, 3-phosphoglycerate dehydrogenase and ribosomal protein S29. The expressed level of carbonic anhydrase XII, clusterin, MRP3s1 protein, complement 3, membrane cofactor protein and integrin beta 1 were decreased. Conclusion: Many of the gene products are membrane-associated proteins. The main mechanism of photodynamic therapy with using the photosensitizing agent DH-I-180-3 appears to be necrosis and this may be associated with the altered production of membrane proteins.