Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A potentially novel therapeutic strategy for breast cancer treatment involves sensitization of tumor cells to chemotherapy through gene transfer. Clinical application of this approach, however, may be limited by the lack of target cell specificity of currently available gene delivery techniques. Development of vectors with tumor-selective gene expression could overcome this problem. The DF3/MUC1 gene encodes a high molecular weight mucin-like glycoprotein which is overexpressed at the transcriptional level in the majority of human breast cancers. To develop a breast tumor-selective enhancer, we cloned the upstream region of the DF3 gene and have identified a 114-base pair enhancer region that can modulate transcription from heterologous promoters. The present studies demonstrate that the DF3 enhancer sequences can direct selective gene expression in DF3-positive breast carcinoma cells. DF3-positive breast carcinoma cell lines transfected with herpes simplex virus thymidine kinase gene expression cassettes modified by the DF3 enhancer were markedly more sensitive to killing by ganciclovir than were the same cells transfected with the expression cassettes lacking the DF3 enhancer. DF3-negative cell lines transfected with the DF3 enhancer constructs, however, were no more sensitive to ganciclovir than were cells treated with the unmodified expression plasmids. Consistent with an innocent bystander effect, nontransfected human breast carcinoma cells were susceptible in a cell density-dependent manner to ganciclovir-induced cell killing when adjacent to transfected cells. The results also demonstrate that the DF3 enhancer sequences can be effectively incorporated into a retroviral vector to mediate selective gene expression following retroviral infection. These findings suggest that the DF3 promoter/enhancer may be useful for incorporation into vectors designed for gene therapy of breast cancer.
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PMID:Enhancer sequences of the DF3 gene regulate expression of the herpes simplex virus thymidine kinase gene and confer sensitivity of human breast cancer cells to ganciclovir. 792 73

The high molecular weight mucin-like glycoprotein, DF3 (MUC1), is overexpressed in the majority of human breast cancers. Here we demonstrate that replication defective recombinant adenoviral vectors, containing the DF3 promoter (bp -725 to +31), can be used to express beta-galactosidase (Ad.DF3-betagal) and the herpes simplex virus thymidine kinase (HSV-tk) gene (Ad.Df3-tk) in DF3 positive breast carcinoma cell lines. In vivo experiments using breast tumor implants in nude mice injected with Ad.DF3-betagal demonstrated that expression of the beta-galactosidase gene is limited to DF3-positive breast cancer xenografts. Moreover, in an intraperitoneal breast cancer metastases model, we show that i.p. injection of Ad.DF3-tk followed by GCV treatment results in inhibition of tumor growth. These results demonstrate that utilization of the DF3 promoter in an adenoviral vector can confer selective expression of heterologous genes in breast cancer cells in vitro and in vivo.
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PMID:Breast cancer selective gene expression and therapy mediated by recombinant adenoviruses containing the DF3/MUC1 promoter. 867 47

In order to exploit differences in gene expression between normal and malignant cells for genetic prodrug-activation therapy, we have generated recombinant retroviruses containing the herpes simplex virus thymidine kinase coding region cloned downstream of sequences derived from the 5'-flanking regions of the MUC1 and ERBB2 genes. Transduction with retroviruses containing MUC1 promoters resulted in an increase in GCV sensitivity in MUC1 positive cells. A further increase in GCV sensitivity was achieved when MUC1-positive cells were transduced with retroviruses containing chimeric-MUC1/ERBB2 promoters. No significant sensitization to GCV was observed when MUC1-negative cells were transduced with these recombinant retroviruses. These results suggest that one may be able to develop a tumour-selective therapy by utilizing the transcriptional regulatory regions of the MUC1 and ERBB2 genes to drive the expression of suicide genes.
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PMID:Use of transcriptional regulatory elements of the MUC1 and ERBB2 genes to drive tumour-selective expression of a prodrug activating enzyme. 941 10

Adenoviruses are efficient gene delivery agents for a variety of neoplasms. In the present study, we have investigated the use of adenoviruses for the delivery of the thymidine kinase (tk) gene into multiple myeloma (MM) cells. We first demonstrated that MM cell lines and MM patient cells express both adenovirus receptors as well as the DF3/MUC1 protein, thus providing a rationale for using adenoviruses to selectively deliver genes under the control of the DF3 promoter. By using an adenoviral construct containing beta-galactosidase (beta-gal) gene driven by the DF3 promoter (Ad. DF3-betagal), we demonstrate greater than 80% transduction efficiency in OCI-My5 and RPMI 8226 MM cell lines at a multiplicity of infection of 1 to 100. Importantly, transduction with the tk gene driven by the DF3 promoter (Ad.DF3-tk) followed by treatment with 50 micromol/L ganciclovir (GCV) purged >/=6 log of contaminating OCI-My5 and RPMI 8226 MM cells within bone marrow mononuclear cells. In contrast, normal human hematopoietic progenitor cell number was unaffected under these conditions. Selectivity of DF3/MUC1 promoter was further confirmed, because Ad.DF3-betagal or Ad.DF3-tk did not transduce MUC1-negative HeLa cervical carcinoma cells. In addition, GCV treatment of Ad.DF3-tk-transduced RPMI 8226 MM cells did not induce a significant bystander effect. These findings demonstrate that transduction with Ad vectors using a tumor-selective promoter provides a highly efficient and selective approach for the ex vivo purging of MM cells.
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PMID:Adenovirus vector-based purging of multiple myeloma cells. 984 25

Because the MUC1 mucin is highly expressed in breast and other carcinomas, interest is focused on the MUC1 promoter, particularly in the context of the delivery of genes to carcinomas. Earlier in vitro studies showed that the region between -152 and -66 of the MUC1 promoter is required for transcriptional activity in MUC1-expressing cells. Experiments reported here showed that sequences -119/-62 within this region are able to modulate transcription of the heterologous constitutively active herpes simplex virus thymidine kinase promoter in a pattern consistent with MUC1 expression. Band-shift experiments showed that although several factors (including Sp1 and Sp3) bind to these sequences, the element important in directing this MUC1 pattern of expression was an Sp1 GC box at -97. The data also show that the positioning or phase of the GC box was crucial for directing expression. The importance of the Sp1 transcription factor was confirmed by demonstrating that overexpression of Sp1 in MUC1-nonexpressing cells increased, not only the expression of a reporter gene driven by the 1.4-kb MUC1 promoter, but also the expression of MUC1 from the endogenous gene. Together, these data define an important role for Sp1 in the cell type-specific transcription of MUC1.
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PMID:The Sp1 transcription factor regulates cell type-specific transcription of MUC1. 1131 16