Browsing by Subject "gene targeting"

Now showing 1 - 3 of 3

Open Access
Differential p21 expression after ionizing and UVC radiation in EBV-transformed lymphoblastoid cells
(2000) Moyret-Lalle, C.; Lalle P.; Pedeux, R.; Guillot, C.; Martel, S.; Magaud J.-P.; Puisieux, A.; Ozturk, M.
Responses to DNA-damaging agents appear to be coordinated by p53 through transcriptional activation of critical target genes. Among them, p21WAF1 encodes a protein preventing cells from entering S phase. It is not clear whether p53-mediated response varies depending on the type of DNA damage. Here, we have decided to compare the p53-mediated response of EBV-transformed lymphoblasts to ionizing radiation and UVC irradiation. We have shown that these cells respond to ionizing radiation by a cell cycle arrest as expected. Surprisingly they failed to do so after UVC treatment. Accordingly there was no significant induction of p21 protein in UVC exposed cells despite p53 accumulation. Using isogenic EBV-transformed lymphoblastoid cells expressing E6 protein of HPV18, we have demonstrated that there was no evidence of p53-dependent cell cycle arrest after UVC irradiation. These observations suggest that the p53-mediated response to UVC, in contrast to ionizing radiation, was compromised in EBV-transformed cells and might be cell type-dependent.
Open Access
Herpes simplex virus 1 amplicon vector-mediated siRNA targeting epidermal growth factor receptor inhibits growth of human glioma cells in vivo
(2005) Saydam O.; Glauser, D.L.; Heid I.; Turkeri G.; Hilbe, M.; Jacobs, A.H.; Ackermann, M.; Fraefel, C.
In primary glioblastomas and other tumor types, the epidermal growth factor receptor (EGFR) is frequently observed with alterations, such as amplification, structural rearrangements, or overexpression of the gene, suggesting an important role in glial tumorigenesis and progression. In this study, we investigated whether posttranscriptional gene silencing by vector-mediated RNAi to inhibit EGFR expression can reduce the growth of cultured human gli36 glioma cells. To "knock down" EGFR expression, we have created HSV-1-based amplicons that contain the RNA polymerase III-dependent H1 promoter to express double-stranded hairpin RNA directed against EGFR at two different locations (pHSVsiEGFR I and pHSVsiEGFR II). We demonstrate that both pHSVsiEGFR I and pHSVsiEGFR II mediated knock-down of transiently transfected full-length EGFR or endogenous EGFR in a dose-dependent manner. The knock-down of EGFR resulted in the growth inhibition of human glioblastoma (gli36-luc) cells both in culture and in athymic mice in vivo. Cell cycle analysis and annexin V staining revealed that siRNA-mediated suppression of EGFR induced apoptosis. Overall HSV-1 amplicons can mediate efficient and specific posttranscriptional gene silencing. Copyright © The American Society of Gene Therapy.
Open Access
Identification of endogenous reference genes for qRT-PCR analysis in normal matched breast tumor tissues
(Cognizant Communication Corporation, 2009) Gur-Dedeoglu, B.; Konu, O.; Bozkurt, B.; Ergul, G.; Seckin, S.; Yulug, I. G.
Quantitative gene expression measurements from tumor tissue are frequently compared with matched normal and/or adjacent tumor tissue expression for diagnostic marker gene selection as well as assessment of the degree of transcriptional deregulation in cancer. Selection of an appropriate reference gene (RG) or an RG panel, which varies depending on cancer type, molecular subtypes, and the normal tissues used for interindividual calibration, is crucial for the accurate quantification of gene expression. Several RG panels have been suggested in breast cancer for making comparisons among tumor subtypes, cell lines, and benign/malignant tumors. In this study, expression patterns of 15 widely used endogenous RGs (ACTB, TBP, GAPDH, SDHA, HPRT, HMBS, B2M, PPIA, GUSB, YWHAZ2, PGK1, RPLP0, PUM1, MRPL19, and RPL41), and three candidate genes that were selected through analysis of two independent microarray datasets (IL22RA1, TTC22, ZNF224) were determined in 23 primary breast tumors and their matched normal tissues using qRTPCR. Additionally, 18S rRNA, ACTB, and SDHA were tested using randomly primed cDNAs from 13 breast tumor pairs to assess the rRNA/mRNA ratio. The tumors exhibited significantly lower rRNA/mRNA ratio when compared to their normals, on average. The expression of the studied RGs in breast tumors did not exhibit differences in terms of grade, ER, or PR status. The stability of RGs was examined based on two different statistical models, namely GeNorm and NormFinder. Among the 18 tested endogenous reference genes, ACTB and SDHA were identified as the most suitable reference genes for the normalization of qRTPCR data in the analysis of normal matched tumor breast tissue pairs by both programs. In addition, the expression of the gelsolin (GSN) gene, a well-known downregulated target in breast tumors, was analyzed using the two most suitable genes and different RG combinations to validate their effectiveness as a normalization factor (NF). The GSN expression of the tumors used in this study was significantly lower than that of normals showing the effectivity of using ACTB and SDHA as suitable RGs in this set of tumor–normal tissue panel. The combinational use of the best performing two RGs (ACTB and SDHA) as a normalization factor can be recommended to minimize sample variability and to increase the accuracy and resolution of gene expression normalization in tumor–normal paired breast cancer qRT-PCR studies.