Dataset Information

In vitro evaluation of cancer-specific NF-kappaB-CEA enhancer-promoter system for 5-fluorouracil prodrug gene therapy in colon cancer cell lines.

ABSTRACT: Nuclear factor-kappa B (NF-kappaB) is a transcription factor with high transcriptional activity in cancer cells. In this study, we developed a novel enhancer-promoter system, kappaB4-CEA205, in which the basal carcinoembryonic antigen (CEA) promoter sequence (CEA205) was placed downstream of the four tandem-linked NF-kappaB DNA-binding sites (kappaB4). In combination with a kappaB4 enhancer, the transcriptional activity of the CEA promoter was significantly enhanced (three- to eight-fold) in cancer cell lines but not in normal cells. In cancer cell lines, the transcriptional activity of kappaB4-CEA205 was comparable with that of the SV40 promoter. We also constructed vectors in which the thymidine phosphorylase (TP) cDNA was under the control of CEA205, kappaB4, kappaB4-CEA205 and CMV promoters, respectively. TP protein and enzyme activity were detected at comparable levels in kappaB4-CEA205- and CMV-driven TP cDNA-transfected cancer cell lines (H630 and RKO). The kappaB4-TP and CEA205-TP-transfected cell lines, respectively, only demonstrated negligible and low levels of TP protein and enzyme activity. Both CMV- and kappaB4-CEA205-driven TP cDNA transiently transfected cells were 8- to 10-fold sensitised to 5-fluorouracil (5-FU) prodrug, 5'-deoxy-5-fluorouradine (5'-DFUR), in contrast to only 1.5- to 2-fold sensitised by the kappaB4- and CEA205-driven TP cDNA-transfected cells. The bystander killing effect of CMV- and kappaB4-CEA205-driven TP cDNA-transfected cells was comparable. This is the first report that indicates that the NF-kappaB DNA-binding site could be used as a novel cancer-specific enhancer to improve cancer-specific promoter activity in gene-directed enzyme prodrug therapy.

SUBMITTER: Guo X

PROVIDER: S-EPMC2360387 | biostudies-literature | 2007 Sep

REPOSITORIES: biostudies-literature

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In vitro evaluation of cancer-specific NF-kappaB-CEA enhancer-promoter system for 5-fluorouracil prodrug gene therapy in colon cancer cell lines.

Guo X X Evans T R J TR Somanath S S Armesilla A L AL Darling J L JL Schatzlein A A Cassidy J J Wang W W

British journal of cancer 20070807 6

Nuclear factor-kappa B (NF-kappaB) is a transcription factor with high transcriptional activity in cancer cells. In this study, we developed a novel enhancer-promoter system, kappaB4-CEA205, in which the basal carcinoembryonic antigen (CEA) promoter sequence (CEA205) was placed downstream of the four tandem-linked NF-kappaB DNA-binding sites (kappaB4). In combination with a kappaB4 enhancer, the transcriptional activity of the CEA promoter was significantly enhanced (three- to eight-fold) in can ...[more]

PMID: 17687334

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Project description:Background5-Fluorouracil (5-FU) represents one of the major constituents of chemotherapy combination regimens in colon cancer (CRC) treatments; however, this regimen is linked with severe adverse effects and chemoresistance. Thus, developing more efficient approaches for CRC is urgently needed to overcome these problems and improve the patient survival rate. Currently, 17β-estradiol (E2) has gained greater attention in colon carcinogenesis, significantly lowering the incidence of CRC in females at reproductive age compared with age-matched males.AimsThis study measured the effects of E2 and/or 5-FU single/dual therapies on cell cycle progression and apoptosis against human HT-29 female and SW480 male primary CRC cells versus their impact on SW620 male metastatic CRC cells.MethodsThe HT-29, SW480, and SW620 cells were treated with IC50 of E2 (10 nM) and 5-FU (50 μM), alone or combined (E+F), for 48 h before cell cycle and apoptosis analyses using flow cytometry.ResultsThe data here showed that E2 monotherapy has great potential to arrest the cell cycle and induce apoptosis in all the investigated colon cancer cells, with the most remarkable effects on metastatic cells (SW620). Most importantly, the dual therapy (E+F) has exerted anti-cancer activities in female (HT-29) and male (SW480) primary CRC cells by inducing apoptosis, which was preferentially provoked in the sub-G1 phase. However, the dual treatment showed the smallest effect in SW620 metastatic cells.Conclusionthis is the first study that demonstrated that the anti-cancer actions of 17β-estradiol and 5-Fluorouracil dual therapy were superior to the monotherapies in female and male primary CRC cells; it is proposed that this treatment strategy could be promising for the early stages of CRC. At the same time, 17β-estradiol monotherapy could be a better approach for treating the metastatic forms of the disease. Nevertheless, additional investigations are still required to determine their precise therapeutic values in CRC.

Project description:BackgroundThe nuclear factor-kappaB (NF-kappaB) family of transcription factors plays a role in a wide range of cellular processes including the immune response and cellular growth. In addition, deregulation of the NF-kappaB system has been associated with a number of disease states, including cancer. Therefore, insight into the regulation of NF-kappaB activation has crucial medical relevance, holding promise for novel drug target discovery. Transcription of NF-kappaB-induced genes is regulated by differential dynamics of single NF-kappaB subunits, but only a few methods are currently being applied to study dynamics. In particular, while oscillations of NF-kappaB activation have been observed in response to the cytokine tumor necrosis factor alpha (TNFalpha), little is known about the occurrence of oscillations in response to bacterial infections.ResultsTo quantitatively assess NF-kappaB dynamics we generated human and murine monoclonal cell lines that stably express the NF-kappaB subunit p65 fused to GFP. Furthermore, a high-throughput assay based on automated microscopy coupled to image analysis to quantify p65-nuclear translocation was established. Using this assay, we demonstrate a stimulus- and cell line-specific temporal control of p65 translocation, revealing, for the first time, oscillations of p65 translocation in response to bacterial infection. Oscillations were detected at the single-cell level using real-time microscopy as well as at the population level using high-throughput image analysis. In addition, mathematical modeling of NF-kappaB dynamics during bacterial infections predicted masking of oscillations on the population level in asynchronous activations, which was experimentally confirmed.ConclusionsTaken together, this simple and cost effective assay constitutes an integrated approach to infer the dynamics of NF-kappaB kinetics in single cells and cell populations. Using a single system, novel factors modulating NF-kappaB can be identified and analyzed, providing new possibilities for a wide range of applications from therapeutic discovery and understanding of disease to host-pathogen interactions.

Project description:BackgroundThe Tax protein encoded by Human T-lymphotropic virus type 1 (HTLV-1) is a powerful activator of the NF-κB pathway, a property critical for HTLV-1-induced immortalization of CD4⁺ T lymphocytes. Tax permanently stimulates this pathway at a cytoplasmic level by activating the IκB kinase (IKK) complex and at a nuclear level by enhancing the binding of the NF-κB factor RelA to its cognate promoters and by forming nuclear bodies, believed to represent transcriptionally active structures. In previous studies, we reported that Tax ubiquitination and SUMOylation play a critical role in Tax localization and NF-κB activation. Indeed, analysis of lysine Tax mutants fused or not to ubiquitin or SUMO led us to propose a two-step model in which Tax ubiquitination first intervenes to activate IKK while Tax SUMOylation is subsequently required for promoter activation within Tax nuclear bodies. However, recent studies showing that ubiquitin or SUMO can modulate Tax activities in either the nucleus or the cytoplasm and that SUMOylated Tax can serve as substrate for ubiquitination suggested that Tax ubiquitination and SUMOylation may mediate redundant rather than successive functions.ResultsIn this study, we analyzed the properties of a new Tax mutant that is properly ubiquitinated, but defective for both nuclear body formation and SUMOylation. We report that reducing Tax SUMOylation and nuclear body formation do not alter the ability of Tax to activate IKK, induce RelA nuclear translocation, and trigger gene expression from a NF-κB promoter. Importantly, potent NF-κB promoter activation by Tax despite low SUMOylation and nuclear body formation is also observed in T cells, including CD4⁺ primary T lymphocytes. Moreover, we show that Tax nuclear bodies are hardly observed in HTLV-1-infected T cells. Finally, we provide direct evidence that the degree of NF-κB activation by Tax correlates with the level of Tax ubiquitination, but not SUMOylation.ConclusionsThese data reveal that the formation of Tax nuclear bodies, previously associated to transcriptional activities in Tax-transfected cells, is dispensable for NF-κB promoter activation, notably in CD4⁺ T cells. They also provide the first evidence that Tax SUMOylation is not a key determinant for Tax-induced NF-κB activation.

Dataset Information

In vitro evaluation of cancer-specific NF-kappaB-CEA enhancer-promoter system for 5-fluorouracil prodrug gene therapy in colon cancer cell lines.

Publications

In vitro evaluation of cancer-specific NF-kappaB-CEA enhancer-promoter system for 5-fluorouracil prodrug gene therapy in colon cancer cell lines.

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